Heat exchanger and method of manufacturing the heat exchanger

Abstract

The disclosure relates to a tubular condenser for a heat pump system for exchanging heat between a refrigerant and water in a container. The condenser comprising a tube (11) through which the refrigerant is to flow via a first tube end being a refrigerant inlet of the condenser and a second tube end being a refrigerant outlet of the condenser. The tube (11) of the condenser has a length which at least partly comprises a varying cross-sectional shape (A, B, C, D). The disclosure also relates to a method of manufacturing the tubular condenser.

Description

Technical field

[0001] The present disclosure relates to a heat exchanger for use in a system for heating water in a container by means of a condenser comprising a tube to let through a flow of a refrigerant in gas or vapor and fluid / liquid form. The present disclosure also relates to a method of manufacturing a condenser comprising a tube for use in a heat exchanger. More specifically, the disclosure relates to a heat exchanger for use in a heat pump system, a condenser for use in the heat exchanger of the heat pump system, the condenser comprising a tube configured to enable heat exchange between a refrigerant in the condenser tube and water in a container, and a method for manufacturing said tubular condenser.Background art

[0002] An example of a prior art condenser is disclosed in US 2025 / 0012483 A1 using a tube wrapped or coiled around a water tank for heat exchange with the water in the tank.

[0003] Due to the concern for the effects of the release and / or leakage of Hydrofluorocarbons (HFC) refrigerants on the global environment caused by the high global warming potential of these substances, there is a large interest in the world, and particularly in Europe, for the use of natural refrigerants, as hydrocarbons, instead of HFCs.

[0004] A problem with the solutions of the prior art, using different kinds of hydrocarbons as refrigerants to heat and / or cool, e.g., food products and / or tap water, such as in refrigerators, freezers, water heaters or the like, is that the leakage of such refrigerants from pipe couplings etc. may incur risk of explosions and / or fires as hydrocarbons are inflammable substances. Examples of known hydrocarbons used in heat exchange processes are propane (C 3 H 8 ) being used in refrigeration cycles and as a refrigerant in heat pumps, isobutane and butane (C 4 H 10 ).

[0005] There is thus a need for improving devices using hydrocarbons as refrigerants, such as propane, for heat exchange and the manufacturing process of such devices.Summary

[0006] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above-mentioned problem / -s. According to a first aspect there is provided a condenser for use in a heat pump system for exchanging heat between a refrigerant and water in a container, the condenser comprising a tube through which the refrigerant is configured to flow via a first tube end being a refrigerant inlet of the condenser and a second tube end being a refrigerant outlet of the condenser, wherein the tube of the condenser has a length and a height in the vertical direction, which length at least partly comprises a varying cross-sectional shape along one or more length sections having at least one or more different and / or one or more similar and / or one or more of the same varying cross-sectional shapes between the two tube ends, and the tube is configured with a helical or spiral shape having an inner size and / or inner shape and / or inner circumference and / or inner diameter being adapted to the outside and / or outer size and / or outer surface and / or shell and / or outer shape and / or outer circumference and / or outer diameter of the container, wherein the inner shape and / or inner circumference and / or inner diameter of the helically shaped tube of the condenser comprises an inner flat surface along the length and height of the helically shaped tube, the inner flat surface being configured to face radially towards and be at least partly or substantially or fully in contact with the outer shell surface of the container, characterized in that the height of the helically shaped tube is increasing along at least two length sections in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0007] According to some aspects, the helically shaped tube of the condenser is configured with an outer size and / or outer shape and / or outer surface and / or outer area having an outer circumference and / or outer diameter comprising an outer at least partly indented and / or at least partly flat surface along the length and height of the helically shaped tube, the outer partly indented and / or partly flat surface being configured to face radially outwards from the outer surface or shell of the container.

[0008] According to some aspects, the height of the helically shaped tube is increasing along at least two, three or more length sections from lower to greater heights in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0009] According to some aspects, the inner flat surface and / or the outer surface of the helically shaped tube of the condenser is / are configured to extend along a substantial part of the height of the helically shaped tube or is / are configured to extend along a substantial part of the full height of the helically shaped tube or is / are configured to extend along almost or nearly the whole full height of the helically shaped tube.

[0010] According to some aspects, the tube of the condenser comprises at least two length sections having at least one partly varying cross-sectional shape with partly varying inner volume differing from each other's cross-sectional shapes and inner volumes and / or differing from any cross-sectional shape and inner volume of one or more of the other length sections of the tube in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0011] According to some aspects, the tube of the condenser comprises at least two length sections of which each has at least one partly varying cross-sectional shape with partly varying inner volume differing from each other's cross-sectional shapes and inner volumes and / or differing from any cross-sectional shape and inner volume of one or more of the other length sections of the tube along the length of the tube with at least two length sections upstream at least a third or fourth or fifth or last length section in the direction of flow of the refrigerant having lower heights and larger inner volumes than at least the downstream third or fourth or fifth or last length section closest to the outlet.

[0012] According to some aspects, the inner flat surface and the outer surface of the helically shaped tube of the condenser are arranged opposite each other and are flattened to different extents or to similar extent or the same extent along the height of the helically shaped tube.

[0013] According to some aspects, the inner flat surface of the helically shaped tube of the condenser is configured to extend along or cover a greater extent of the height of the helically shaped tube compared to the outer surface of the helically shaped tube.

[0014] According to some aspects, the tube of the condenser is configured to be a separate detail / item / part and detachably arranged or coiled around the outside of the container in the heat pump system.

[0015] According to some aspects, the length of the tubular condenser comprises at least two length sections, a first length section with a first at least partly varying cross-sectional shape and a first at least partly varying inner volume and a second length section with a second at least partly varying cross-sectional shape and a second at least partly varying inner volume, which first at least partly varying inner volume is larger than the second at least partly varying inner volume in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0016] According to some aspects, the length of the tube of the condenser comprises at least a third or fourth or more length sections with at least partly varying third or fourth or more cross-sectional shapes providing at least partly varying third or fourth or more inner volumes, respectively, being smaller than the first at least partly varying inner volume and / or the second at least partly varying inner volume of the first and / or second length sections in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0017] According to some aspects, the lengthwise at least partly varying cross-sectional shape of the tube of the condenser is configured to vary between the first tube end and the second tube end, which at least partly varying cross-sectional inner shape and area is configured to provide an inner volume that at least partly decreases along the length of the tube in the flow direction of the refrigerant to the second tube end.

[0018] According to some aspects, the length of the tube of the condenser comprises at least two length sections providing a first length part forming half of the full length of the whole tube and a second length part forming the other half of the full length of the whole tube, which first length part comprises a larger inner volume than the second length part of the length of the tube.

[0019] According to some aspects, the helical or spiral shape of the tube of the condenser is configured as a helix with constant pitch or varying pitch and / or as a helix with any combination of any constant pitch and / or any varying pitch.

[0020] According to some aspects, the helical or spiral shape of the tube of the condenser is configured as a helix with the distance between each turn or pitch being constant along a part or along the whole length or height and the axis of the helix or is configured as a variable-pitch helix with a pitch varying or changing along at least a part of the length or height and axis of the helix or is configured as a variable-pitch helix with a pitch varying or changing along the whole length or height and axis of the helix or is configured as a variable-pitch helix having a first pitch varying or changing along at least a part of the length or height and axis of the helix and a second pitch being constant along at least another part of the length or height and axis of the helix.

[0021] According to some aspects, the helical or spiral shape of the tube of the condenser is configured as a helix with the distance between the turns or pitch being larger along at least a first length section of the helix along the height and axis of the helix and smaller along at least another or second or third or fourth length section of the helix along the height and axis of the helix.

[0022] According to some aspects, the tube of the condenser is configured as a helix with the distance between the turns or the pitch decreasing along a first length section of the helix tube to a second length section of the helix tube along which second length section of the helix tube the pitch increases to a third or fourth length section of the helix tube along which third or fourth length section of the helix tube the pitch decreases again along the axis of the helix.

[0023] According to some aspects, one or more of the length section(s) of the helical or helix or spiral shape of the tube of the condenser is(are) provided with the same distance between the turns or the same pitch and / or which length sections of the helix is a combination of one or more length sections having a constant pitch and one or more length sections having an at least partly varying pitch or which length sections of the helix is a combination of one or more length sections having a decreasing pitch and one or more length sections having an increasing pitch.

[0024] According to some aspects, the helical or spiral shape of the tube of the condenser is provided with at least one length section arranged closer to or at or adjacent or ending at or where the second tube end begin as seen in the direction of flow of refrigerant, which at least one length section has a varying pitch decreasing along the axis of the helix forming a denser or the densest pitch closer to or at or adjacent or ending at where the second tube end begin.

[0025] According to some aspects, the first tube end being the refrigerant inlet of the condenser and the second tube end being the refrigerant outlet of the condenser have lengths with cross-sectional shapes that are not changed or similar to each other's cross-sectional shapes or have the same cross-sectional shapes and / or sizes and / or diameters.

[0026] According to some aspects, each of the first tube end and the second tube end of the condenser has a circular cross-sectional shape along the length.

[0027] This makes the coupling of the condenser, i.e., the tubular ends of the condenser, to the heat pump system easier while providing sufficient sealing as the cross-sections of the respective ends do not change and / or is circular therefore enabling using standard tube couplings or connecting means.

[0028] According to some aspects, the length of the tube comprises at least two length sections, each length section having one or more at least partly varying and at least partly non-circular cross-sectional shapes along at least a part of the tube length between the first and the second tube ends.

[0029] According to some aspects, the one or more at least partly varying and at least partly non-circular cross-sectional shapes of any length section of the length of the tube has / have at least partly or fully a flat sided oval shape or at least partly or fully a flat sided elliptic shape or at least partly or fully a rounded rectangle shape or at least partly or fully a stadium shape.

[0030] According to some aspects, the refrigerant comprises propane or is propane, C 3 H 8 .

[0031] This provides an improved and more robust heat exchange and control thereof by usage of a refrigerant with excellent thermodynamic properties and ability to efficiently transfer heat and easy availability for a relatively low cost.

[0032] According to some aspects, the one or more at least partly varying and at least partly non-circular cross-sectional shapes of at least one or preferably at least two or more or all length sections of the length of the tube has / have the inner flat surface forming a straight plane extending in parallel with the center axis of the helical tube and the outer surface forming an at least partly flat and straight plane opposite and in parallel with the inner flat surface and extending along the tube in the same way as the inner flat surface.

[0033] According to some aspects, the one or more at least partly varying and at least partly non-circular cross-sectional shapes of at least one or preferably at least two or more or all length sections of the length of the tube has / have the inner flat surface forming a straight plane extending in parallel with the center axis of the helical tube and the outer surface forming an at least partly non-straight or non-flat surface or at least partly radially inwards extending or indented surface.

[0034] Any of the aspects above and below provides an optimized use of a small charge of a hydrocarbon, e.g., a propane charge being between 130 to 160 grams, preferably about 135 to 155 grams or more preferred about 140 to 154 grams or between 148 to 153 grams or most preferred about 152 or exactly 152 grams. Any of the aspects above and below provides reducing the risk of combustion due to leakage of propane while still providing an efficient heat exchange between the refrigerant in the tube and the water in the container due to the combination of increased contact area between the inside of the tube and the outer shell of the container and the decreased outer radial "size" or occupied external space by means of the tube due to the decreased radial extension of the outer side of the tube giving room for more insulation around the container and the tube to further enhance the desired direction of the heat flow towards and into the water inside the container.

[0035] Any of the aspects above and below provides the ability to optimize the refrigerant quantity across the heat exchanger, while minimizing the overall pressure losses - and more uniform pressure profile across the condenser - and increasing the heat transfer area.

[0036] Any of the aspects above and below provides the ability to assemble, manufacture and operate a heat pump system with improved efficiency and reduced operating, maintenance and manufacturing costs.

[0037] Any of the aspects above and below provides an ability to use a smaller charge of a hydrocarbon, such as propane, as a refrigerant as the charge of a combustible hydrocarbon is one of the restricting criteria when designing solutions of heat exchange systems used in households, i.e., the total amount of refrigerant, measured by weight, being the charge of a hydrocarbon, e.g., propane, should not exceed about 150 - 152 grams in said system to reduce the risk of combustion if leakage of hydrocarbon occurs and also enables this inventive solution to fulfil regulatory demands in as many jurisdictions as possible, e.g., in Europe.

[0038] Any of the aspects above and below reduce the risk of having a heat pump with refrigerant charge lower than needed, that would lead to a poor heat pump efficiency.

[0039] According to a second aspect, there is provided a method of manufacturing a condenser for use in a heat pump system to exchange heat between a refrigerant and water (in a container, the condenser comprising a tube with two tube ends and a length therebetween for letting the refrigerant through and a height in the vertical direction, the method comprising introducing a first tube end into a tube forming machine before a second tube end is introduced therein, feeding the first tube end and the length of the tube through the tube forming machine and forming the tube at least partly along at least a first section and a second section of the tube length into at least one or more varying cross-sectional shapes and with at least two flat and opposite surfaces or with one inner flat surface and one at least partly indented and / or at least partly flat outer surface along at least a part of each tube length section, winding or coiling each tube length section into a helically shaped tube around the shell of the container with the flat inner surface facing radially inwards forming an inner flat contact surface at least partly or substantially or fully in contact with a first area of the outer shell of the container, and increasing the height of the helically shaped tube along at least two length sections from lower to greater heights in the direction from the first tube end to the second tube end.

[0040] According to some aspects, the method comprises winding or coiling each of the length sections into the helically shaped tube around the container with the inner flat contact surface facing radially inwards and at least partly or substantially or fully in contact with an area of the outer shell surface of the container being different from any outer area or shell area of the container that any other tube length section is winded or coiled around.

[0041] According to some aspects, the method comprises forming, by means of the tube forming machine at least a first tube length section into a first varying cross-sectional shape and a first varying inner volume of the first half of the length of the tube and forming at least a second tube length section into a second varying cross-sectional shape with a second varying inner volume of the second half of the tube length, which second varying inner volume is smaller than the first varying inner volume of the first tube length section.

[0042] This provides an easier manufacturing of the tube of the condenser by not having to form or reshape the whole length of the tube while also simplifying the coupling of the condenser ends to the heat pump system and enables achieving an improved and more secure sealing as the cross-sections of the respective ends do not change and / or is circular therefore enabling using standard tube couplings or connecting means.

[0043] Hence, by increasing the height of the condenser tube along at least two length sections of the tube and actually decreasing the tube width along at least the same two or more length sections at the same time in the flow direction of the refrigerant - primarily decreasing the inner width and increasing the inner height of the tube even though the outer and the inner widths / heights of the tube correlate but this correlation of course depends on the thickness of the material of the tube as the inner width and inner height factually form / enclose / define the inner volume of the tube - in accordance with where the refrigerant has higher density (closer to the outlet of the condenser) and having a lower height and greater width of the tube or a wider tube where the refrigerant has lower density (at or in or closer to the inlet of the condenser) seen in the flow direction of the refrigerant provide three improvements - see below and the disclosure - in performance of the inventive condenser compared to prior art condensers. In other words, these three performance improvements of the inventive condenser are achieved by having a greater / higher / larger internal volume (lower degree of squeezing of the condenser tube closer to the tube inlet) when the refrigerant enters the condenser in gaseous state and a smaller or lower / reduced / decreased internal volume (higher degree of squeezing of the condenser tube closer to and / or adjacent and / or at and / or just before and / or after the tube outlet) when the refrigerant leaves the condenser in liquid state: Reduction of refrigerant charge: When the refrigerant enters the condenser, the refrigerant is in a gaseous state with relatively low density. This initial part or section of the condenser is therefore not particularly sensitive to refrigerant charge. However, as condensation progresses, the refrigerant transitions into a liquid state, and the density of the refrigerant increases significantly, often by a factor of up to 10 compared to the inlet of the condenser, i.e., the tube inlet. This means that length sections after the inlet, in particular the latter part(s) or section(s) of the condenser downstream the inlet, where the refrigerant is mostly liquid, contributes disproportionately to the total system charge. By increasing the height of the condenser tube from the inlet on (by applying a more aggressive squeezing of the tube, i.e., reducing also the width and thereby internal volume) specifically in the later length section(s), in particular in the final length section(s) of the condenser tube, the most charge-sensitive zone of the heat pump system and the condenser is effectively target. This condenser design approach leads to a substantial reduction in the overall refrigerant charge required compared to prior art condensers visualized in figure 9. Reduction of pressure drops: Although the refrigerant density increases significantly in the liquid phase, the velocity of the refrigerant when flowing from the inlet decreases substantially. This lower velocity of the refrigerant allows for a more aggressive increase of the height of the condenser tube along at least two length sections (e.g., by squeezing of the condenser tubing), preferably in and along the latter length sections-where the refrigerant is mostly liquid-without causing excessive pressure drops across the system. This design strategy of the condenser takes advantage of the flow characteristics of the refrigerant: high density but low velocity in the liquid phase means that flow resistance remains manageable even when the internal volume is reduced in the direction of the refrigerant flow along the tube. As a result, the condenser geometry is optimized to reduce refrigerant charge to enable using such low amount of refrigerant and also enhances heat transfer without compromising system performance due to pressure losses as this inventive condenser design strategically applies volume reductions only where they are most effective and least detrimental to flow dynamics when using such a low refrigerant charge below 150 to 155 grams or about 152 to 153 grams. Increase of heat transfer area and improvement of heat transfer coefficient (HTC): The condenser design according to the disclosure enables an adequate heat transfer area by allowing for an increased number of tube windings. This is made possible by the simultaneous reduction in refrigerant charge and pressure drop, which removes previous design constraints and permits a more optimized winding and tube coil layout. Additionally, as the tube is provided with an increased height TH along at least two length sections, preferably more, along the condenser tube in the direction of the refrigerant flow, the flat inner tube surface in contact with the tank also increases enhancing thermal conduction, particularly in the lower part or sections of the condenser. While the heat transfer coefficient (HTC) is generally higher in the two-phase and gaseous regions for the refrigerant, the disclosed condenser design improves HTC even in the liquid phase of the refrigerant. This is achieved through a higher degree or increase of tube height TH (e.g., by squeezing the condenser tube), which increases the inner tube surface contact with the tank and turbulence, without significantly increasing pressure drop. The result is a more efficient and balanced heat exchange process across all phases of the refrigerant by use of this condenser design.

[0044] The invention provides several key advantages that distinguish the disclosed condenser from existing solutions in prior art systems with heat pumps and condensers by enabling the use of low-charge propane systems without compromising performance (main advantage); improves heat pump efficiency (COP) at significantly reduced refrigerant volumes and increases adequate heat exchange area despite reduced internal volume along the condenser in the direction of refrigerant flow.

[0045] The invention also addresses problems not solved by prior art condensers by addressing the challenge of using flammable refrigerants with strict charge limits; introducing a condenser design that balances refrigerant volume reduction with performance optimization; minimizing pressure losses while preserving heat transfer capabilities and provides a scalable and cost-effective solution for next-generation heat pumps using natural refrigerants at low charge, while maintaining high performance(s) by using the higher heat transfer coefficient (HTC) in liquid phase together with higher velocity in the condenser tube with increased (greater) height TH and narrower or thinner width TW towards and at the condenser tube outlet compared to lower velocity closer to and at / in the condenser tube inlet and a greater heat transfer area in the later and / or latest condensing phase of the refrigerant towards and closer to and at the end of the condenser, i.e., towards and at the outlet.

[0046] Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the devices described or steps of any method described since such devices and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular aspects only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claims, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements or entities unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit / device / tube / condenser" or "the unit / device / tubes / condensers" may include one, two or several units and / or devices / tubes / condensers, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings do not exclude other elements or steps of a process or method. According to the disclosure, entities or parts or details without reference numerals and / or denoted as X or X' or X" and / or Y or Y' or Y" are meant to comprise and / or include at least similar shapes and / or functions and / or the same shapes and / or functions as other corresponding entities having similar reference numerals or other denotations, i.e., each and every entity denoted with reference numerals are at least functionally, or even in some embodiments structurally, interchangeable with each and every entity having no reference numerals. This means that entities having reference numerals or other denotations, such as X or X' or X" and / or Y or Y' or Y" above or below, are provided with either exactly the same features or similar or very similar and equally usable and interchangeable feature or comprises at least one or more or all of the same features as the entities without reference numerals and / or entities being denoted as X or X' or X" and / or as Y or Y' or Y", which features could be structural and / or functional features.

[0047] Terminology -- The terms "vertical / horizontal" or "upstanding / laying" are to be interpreted as a relative positioning of entities in relation to the horizontal or vertical plane but not necessarily in directions and / or positions that are exactly aligned with or in these planes and may deviate somewhat from these directions and / or planes within applicable tolerances as understood by a skilled person within the technical field while still being defined as horizontal or vertical or upstanding or laying or extending horizontally or vertically.Brief descriptions of the drawings

[0048] The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example aspects / embodiments of the present disclosure, when taken in conjunction with the accompanying drawings. Figure 1 shows - schematically - a heat pump system according to an aspect of the present disclosure. Figure 2 shows a water container - in a side view - with a tubular condenser wrapped around the water container for use in a heat pump system according to an aspect of the present disclosure. Figure 3A shows - in a perspective view - a tubular condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 3B shows - in a perspective view - a tubular condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 3C shows - in a perspective view - a tubular condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 4A shows - in a side view - a tubular condenser, e.g., as in fig. 3A, separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 4B shows - in a side view - a tubular condenser, e.g., similar to the one in fig. 3B, separately for heat exchange in a heat pump system according to an aspect of the disclosure. Figure 4C shows - in a side view - a tubular condenser, e.g., similar to the one in fig. 3B, separately for heat exchange in a heat pump system according to an aspect of the disclosure. Figure 4D shows - in a side view - a tubular condenser, e.g., as in fig. 3C, separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 5A shows in perspective enlarged cross-sectional parts or sections and / or shapes of the tubular condenser in four cutout views corresponding to the cutout views in fig. 4A. Figure 5B shows - in perspective - enlarged cross-sectional parts or sections and / or shapes of an alternative tubular condenser in four cutout views, the two upper cutout views correspond to the two upper cutout views in fig. 4B, and the two lower cutout views correspond to the two lower cutout views in fig. 4A according to an aspect of the disclosure. Figure 5C shows - in perspective - enlarged cross-sectional parts or sections and / or shapes of the tubular condenser in cutout views corresponding to the cutout views in figs. 4A and 5A. Figure 5D shows - in perspective - enlarged cross-sectional parts or sections and / or shapes of another tubular condenser in three cutout views of which the top cutout view corresponds to the top cutout view in fig. 4B and the top cutout view in fig. 5B while the middle cutout view corresponds to the top cutout views in figs. 4A, 5B and 5C, and the bottom cutout view of fig. 5D corresponds to the top cutout view in fig. 4C and the view in fig. 5G according to an aspect of the present disclosure. Figures 5E to 5G show - in side views - different enlarged cross-sectional parts or sections and / or shapes being applicable for use in a condenser separately and / or in any combination in similar ways or the same way or in other ways of combinations as shown in the ones of figs. 5A to 5D. Figure 5H shows - in a side view - a tubular condenser separately for heat exchange in a heat pump system and - in perspective - enlarged cross-sectional parts or sections and / or shapes of this exemplary tubular condenser in six cutout views according to an aspect of the present disclosure. Figure 5I shows - in a side view - the condenser of fig. 4D separately for heat exchange in a heat pump system and - in perspective views to the right - enlarged cross-sectional parts or sections and / or shapes of this exemplary tubular condenser in thirteen cutout views according to the cutout A - A (main difference between the condensers of figs. 5I and 5H is the vertical height and pitch at / for the tube winding or coiling with shape E, the principle and dimensional parameters and varying shapes of the condenser tube, such as vertical height, width (inner / outer width), inner and outer surfaces are the same or close or very close even if not all dimensions and surfaces in fig. 5I are visualized by numerals and arrows and lines compared to fig. 5H as long as the vertical tube height is larger or the largest (and the width is smaller or the smallest) for the last shape(s) compared to the first shape) according to an aspect of the present disclosure. Figure 6 shows - in a top view from above - a condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 7 shows schematically manufacturing of a tubular condenser by forming the tube around a container according to an aspect of the present disclosure. Figure 8 shows an enlarged cross-section view of a part or section and / or shape being applicable and used in any condenser of figs. 1 to 4D, 5H, 5I, 6 and 7 along or at a tube end or a length or section or a shape transition part as shown at or adjacent or in or as parts of bends or as the whole bends including any tube length closest to and / or adjoining and / or before and / or after each bend encircled by dashed circles in figs. 2 to 4D, 5H, 5I, 6 and 7) and / or along lengths of the two tube ends (as shown in figs. 2 to 4D, 5H, 5I, 6 and 7) with a circular and tubular cross-section according to an aspect of the present disclosure. Figure 9 illustrates refrigerant charge distribution (y-axis) in the condenser along the condenser tube length and along the varying cross-sectional shapes of the tube (x-axis) according to the present disclosure. Detailed description

[0049] The present disclosure will now be described with reference to the accompanying drawings 1 to 9, in which preferred example aspects of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed aspects. The disclosed aspects are provided to fully convey the scope of the disclosure to the skilled person. All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

[0050] In particular, figures 5A, 5C, 5H and 5I show - in perspective - enlarged cross-sectional parts or sections and / or shapes of the invention, a tubular condenser 10, in cutout views (to the right in figs. 5H and 5I) corresponding to the cutout views in figs. 4A, 4D and 5A for enhanced overview of dimensions of these entities not shown by arrows and denotations in figs. 4A, 4D and 5A (such as FI i , FI o , TH (inner and / or outer height in the vertical direction) and TW (inner and / or outer width in the horizontal direction) or in figs. 5C and 5I (such as SD i and SD o shown in figure 6) but which dimensions are applicable to and - in principle - exist in all corresponding entities as referred to in the disclosure and on the drawings including figures 5I and 8 (even though the height and width of shape O is of course the same as it is circular) where the similar or the same entities and / or cross-sectional shapes are shown, see also the nomenclature for clarification of abbreviations, to not having figures showing too many numerals and arrows etc. making them difficult to clearly view. This is due to the fact that each of the applicable cross-sectional shapes used for the tubular condenser 10 of course physically has an inner and outer height, an inner and outer width and thickness even though at least one or two or more or some or all cross-sectional shapes of the tubular condenser may be or are at least partly shaped differently, such as the circular shape O.

[0051] Figure 1 shows a heat pump system 100 according to the disclosure. The heat pump system 100 comprises a container 3. The container 3 is shown to the far right in fig. 1. The container 3 is configured to contain water 2 to be let into the container 3, e.g., by pumping via electrically driven pumps or the like as is known to the skilled person, for heating via an water inlet 4 for non-heated or cold water, and to let the water 2 out of the container after being heated by being pumped out, e.g., as hot water 2 for use when bathing or to shower or for heating of a residential house or a swimming pool via a water outlet 5. The container 3 is preferably made of metal. The control of the pumping and the heating of the water 2 inside the container 3 are provided by use of a suitable number and types of sensors, thermostats, water pumps, such as circulating pumps, valves, tubing etc. besides the components used in the heat pump system 100. The components and functions for handling the water 2 are commonly known by a skilled person, and which water system components are operatively connected to each other and the heat pump system 100 and control units (not shown). Moreover, power is of course provided to drive all the necessary equipment and component as desired in both the water handling system and the heat pump system 100. The working principle of the heat pump system 100 shown in fig. 1 concerns using a heat pump being a device that transfers heat from one place to another by means of a circulating refrigerant 1 used as a medium. The heat pump system 100 as shown in fig. 1 comprises at least four main components: a compressor 110, an evaporator 120, one or more condensers 10 comprising at least one helically-shaped tube 11, and an expansion valve 130 operatively coupled to a control sensor 140 and / or temperature sensor 140 and / or pressure sensor 140.

[0052] In the evaporator 120 as shown in fig. 1, refrigerant 1 absorbs heat from a heat source (water and / or air or the like), causing refrigerant 1 to evaporate and turn into a gas at low pressure. In the compressor 110, this refrigerant gas 1 is then compressed through the compressor 110, which increases the pressure and temperature of the refrigerant gas 1. Then, the condenser 10 receives the refrigerant gas 1 via an inlet pipe connector 16 of the heat pump system 100 flowing into a tube 11 of the condenser 10 via an inlet 12 of the condenser 10 (the condenser tube 11 is wrapped / winded as a separate item and in physical contact with the outside and shell of the container 3 for water 2 to be heated, see fig. 2), whereby the hot, high-pressure refrigerant gas 1 enters the condenser 10. In the condenser 10, the refrigerant gas 1 flows through the condenser tube 11 first releasing excess heat (so called de-superheating) to the condenser tube 11 and further to the outside or shell of the container 3 and to the water 2 inside the container (usually, non-heated water 2 enters the bottom of the container 3 but could in some aspects enter the container at another position or level depending on application and need). As the refrigerant gas 1 continues to flow through the tube 11 and cool in the condenser 10 while flowing around the container 3 following the winding / coiling of the condenser tube 11 due to heat exchange with primarily the container 3 and the water 2, the refrigerant gas 1 transitions from gas to liquid through condensation. During this process, refrigerant 1 is in both gas and liquid forms (two-phase region). Finally, the refrigerant 1 becomes a fully saturated liquid and cools further below the condensation point (subcooling) while flowing through the condenser tube 11 and is finally let out as a colder liquid at an outlet 13 of the condenser 10 being the end of the condenser tube 11 in fluid connection with an outlet pipe connector 17 of the heat pump system 100 and the refrigerant 1 flows into the heat pump cycle again. The density of the refrigerant 1 increases significantly when transitioning from a gas to a liquid in the condenser 10. The liquid refrigerant 1 then enters the expansion valve 130 and the liquid refrigerant 1 passes through this valve 130 dropping in pressure and cooling down before returning to the evaporator 120. The expansion valve 130 regulates the flow of refrigerant according to the temperature measured by the temperature sensor 140 and assures that at the outlet of the evaporator 120, the refrigerant is in superheated vapour state, without liquid droplets. This cycle repeats, moving heat from one place to another, effectively heating the water 2 in the container

[0053] In fig. 2, a tubular condenser 10 according to the disclosure comprises a tube 11 configured to be helically arranged around and in contact with the container 3 by means of an inner surface 14 by being winded or coiled around the outside and shell of the container during manufacture. The contact between the inner surface 14 of the tubular condenser 10 and the outer shell of the container 3, i.e., the tube 11 making up the condenser 10 is in some aspects enhanced by use of a contact enhancing and thermal improving paste applied between the inner surface 14 of the tubular condenser 10 and the outside of the shell of the container 3.

[0054] According to the disclosure, the condenser 10 is configured to be used in any heat pump system 100 for exchanging heat between a refrigerant 1 inside the tube 11 of the condenser 10 and the water 2 in the container 3, commonly during operation of the heat pump system 100. However, in some aspects, heat exchange still occurs during a short still stand or non-operation of the heat pump system 100.

[0055] The condenser 10 and its tube 11 enable throughput of refrigerant 1 coming from the heat pump system 100 via the first tube end 12 shown extending vertically in figs. 2 to 4D but could in some aspects extend horizontally or inclined. The first tube end 12 of the condenser 10 is a refrigerant inlet of the condenser 10. The condenser tube 11 enables throughput and outlet of the refrigerant 1 via the second tube end 13 acting as a refrigerant outlet of the condenser 10 for return into the other parts of the heat pump system 100 and to be used anew in the heat pump cycle if not turned off to not be operating. The second tube end 13 extends vertically in figs. 2 to 4D but could in some aspects extend horizontally or inclined.

[0056] In fig. 2, the tubular condenser 10 is shown after being wrapped or winded or coiled as a spiral or helix around and in contact with the inner surface 14 to the outer shell of the metal container 3 and with an outer surface 15 facing outwards forming the outside of the helically or spirally shaped tubular condenser 10 (see also figs. 3A, 3B, 5A to 5I clearly showing this inner surface 14 arranged to the left, even though fig. 5E could show the opposite as not being in perspective). In fig. 5E, the reference numerals 14 and 15 could actually change place as is clearly understood by a skilled person as inner and outer surfaces 14 and 15 have the same shape and size and / or area and / or height while in figs. 5F, 5G, 5H and 5I, the left inner surface 14 is the one to be in contact with the outer shell of the container 3 to achieve the best heat exchange effect by better contact over a larger area and therefore providing improved conduction, i.e., heat conduction, therewith. The outer surface 15 of the tubular condenser 10 is formed by being flattened similar or in the same way as the inner surface 14 and / or indented radially inwards into a partly inwards bent surface and / or partly flat surface to reduce the radial extension TW of the tube 11 of the condenser to enable the container 3 and the condenser 10 to occupy less total space radially together and give more room or space for insulation around these entities 3 and 10, the insulation is not shown.

[0057] The tube 11 making up the condenser 10 has a length TL (see figs. 2, 3A to 4D, 6 and 7, however, all tubes 11 of the disclosure have of course a length). The length TL of the tube 11 could be the whole tube length or the length between the ends 12 and 13 depending on how long, i.e., the length LE 1 , LE 2 for each of the ends 12 and 13 is, but - according to the disclosure - the length TL of the tube 11 is referred to as the tube length starting where the extension of the first tube end 12 ends - in the flow direction of refrigerant 1- and where the extension of the second or last tube end 13 starts in the flow direction of refrigerant 1. This is due to that the tube ends 12 and 13 and their lengths LE 1 , LE 2 are preferably not formed or shaped with a varying cross-section as the remaining length TL of the tube 11 according to the invention but could be.

[0058] The length TL of the tube 11 at least partly comprises a varying cross-sectional shape A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" along one or more length sections preferably at least two length sections with shape(s) A, A', A" and / or B, B', B" and / or C, C', C", D, D', D" and / or E, E', E", F, F', F" being differing and varying cross-sectional shapes (see figs. 2 to 5I) between the two tube ends 12, 13. Hence, in the disclosure, when referring to any length section(s) denoted with any of the letters A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" this means that the concerned tube length section(s) has / have been formed into one or more of these concerned cross-sectional shapes before being wrapped around the container 3.

[0059] The tube 11 making up the condenser 10 has or is shaped into a helical and / or spiral shape with an inner size and / or inner shape and / or inner surface and / or inner circumference and / or diameter SD i and an outer size and / or outer shape and / or outer circumference / diameter SD o (see figs. 4A to 4C, 5A, 5B, 5D, 5I and 6) being adapted to the outside and / or outer size and / or outer mantle and / or shell surface and / or outer shape and / or outer circumference and / or outer diameter CD o of the container 3 for water 2 by being winded or coiled around the container 3 by use of a device 90, 90'. (see figs. 2 and 7). In some aspects, the condenser 10 comprises a tube 11 made up of at least two length sections of similar or same or equal or different lengths or each of the two length sections has a length being half the tube length TL.

[0060] The device 90, 90' is a tube forming machine with at least two rolls 91, i.e., at least one or more pairs of counterrotating rolls as seen in fig. 7. The tube forming machine 90 is shown schematically as a box in solid lines together with the rolls 91 in fig. 7 at and in operative connection with the first end 12 of the tube 11. In some aspects, a corresponding tube forming machine 90' is shown in dashed lines in fig, 7 at and in operative connection with the second end 13 of the tube 11. This visualizes that either the first tube end 12 or the second tube end 3 can be the first tube end introduced into the tube forming machine 90, 90' and be the first tube end ejected from the tube forming machine to be formed around the container 3. If the second tube end 13 is first introduced into the tube forming machine 90' then the shown arrows in dashed lines visualize the direction of feeding the second tube end 13 while the arrows in solid lines show the feeding direction of the first tube end 12 when being firstly introduced into the tube forming machine 90.

[0061] The rolls 91 are configured to rotate in contact with the tube 11 while forming the cross-sectional shape(s) of one or two or more length sections of the tube into any of the shown varying shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" or forming the cross-sectional shape(s) of one or two or more length sections with any combination of two or more of those cross-sectional shapes of figs. 5A to 5I or 9. The tube forming machine 90, 90' - in some aspects - only forms the length TL of the tube 11 between the lengths LE 1 and LE 2 of the first and the second tube ends 12, 13 being shown in figs. 4A to 4D, as explained above. The lengths LE 1 , LE 2 for each of the tube ends 12 and 13 could be of any length.

[0062] During the forming of the condenser tube 11 while being fed in the directions of the white arrows (shown in solid or dashed lines) in fig. 7, the tube is also winded or coiled around the container 3 into different coil and / or thread patterns and / or pitches of the spirally and / or helically wound and / or helix-shaped tubular condenser 10 along the outer surface and shell of the container and along a vertical center axis CCA of the container and its own vertical center axis SCA as seen in figs. 2, 4A to 4D, and 7. In fig. 7, the top windings or coils at the denotation A, A', A" of the condenser 10 are winded with a pitch being larger than both the intermediate windings or coils at the denotations B, B', B", C, C', C" and the bottom windings or coils at the denotations D, D', D" (and / or compared to the windings E (E', E"), F (F', F") of fig. 5H) - similar to the pitches and winding / coil pattern in figs. 2, 3A and 4A, but these pitches could be made with other and different pitches as shown in figs. 4B and 4D or have the same pitch as shown in figs. 3B and 4C. Hence, also the cross-sectional shapes referred to as A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" (and G, H and I in fig. 9 that also could be shapes G', G" and / or H', H" and / or I', I") in figs. 5A to 5I are possible to combine or apply at different levels or for different winding or coil patterns and / or for different or the same pitches as long as the total inner volume decreases and the total tube height TH increases from the top windings or coils with shape(s) O / A as seen in figs. 2 to 5I, and 7 to and through the bottom windings or coils with shape(s) C, C', B", D, D', E and / or F towards the second tube end 13 with a last shape B, B', B" (if two length sections with different shapes form the condenser tube 11); C, C', C" (if three length sections with different shapes form the condenser tube 11); D, D', D" (if four length sections with different shapes form the condenser tube); E, E', E" (if five length sections with different shapes form the condenser tube) and F, F', F" (if six length sections with different shapes form the condenser tube) transferred into shape O along the bottom bend TRA. In some aspects, the tube length section between the bottom shape transition area or bend TRA with tube shape O and the length LE 2 of the outlet tube end 13 has an increased height TH and shape, such as shape D in figs. 4A, 5A, 5B and 5C; shape D' in fig. 4B; shape C" in fig. 4C, and shape F in figs. 4D and optionally in figs. 5H and 5I to further increase contact surface and heat transfer. In some aspects, the lengths LE 1 and LE 2 for the tube ends 12 and 13 with shape O are minimized to further increase or optimize the length of the tube 11 having the varying shapes A to F" (and / or shapes G to I") to further improve the performance of the condenser 10.

[0063] In some aspects, the at least two rolls 91 of the tube forming machine 90 of fig. 7 may also actively push or feed the tube 11 through and out of the tube forming machine 90 instead of only passively rotating while the tube is pulled through the tube forming machine 90, 90'. In some aspects, the tube end 12 or 13 to be firstly introduced into and fed out of the tube forming machine 90 or 90', respectively, to enable forming the tube 11 around the container 3 is attached by clamping or the like to the container 3, which container then is rotated pulling the tube 11 out of the tube forming machine while bending the tube around its circumference and outer shell until the helically shaped condenser 10 is wrapped around the container with the inner surface 14 in contact with the outer shell of the container 3 (the different rotational directions of the container 3 when being rotated pulling the tube 11 is shown with the lower curved arrows in solid and dashed lines). In some aspects, the container 3 is not filled with water 2 when the tubular condenser 10 is formed around it.

[0064] The tube forming machine 90, 90' uses an adjustability of the distance RD between the rolls 91, such as the distance between the rotary axes of the rolls, to form the cross-sectional shape of the tube 11 from a circular one at and along its ends 12 and 13 to one or more of the varying cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" shown in figs. 5A to 5I along at least two length sections. This forming is primarily increasing the height TH of the tube 11 (both the inner and outer tube height) while decreasing the thickness or width TW of the tube 11 (both the inner and outer tube width) as shown in all views in figs. 3A to 5G and in 5I, and 6, even though these dimensional parameters are not denoted in each view as these dimensional features of course are parts of the actual physical tube 11.

[0065] However, in some aspects, such as in fig. 5H, the first or top cross-sectional shape A or A' or A" provides a smaller inner volume along the first or top length section than the inner volume provided by the next or second length section having the second cross-sectional shape, B or B' or B", e.g., the first or top cross-sectional shape A or A' or A" could have a similar or the same inner volume as the third cross-sectional shape C, C', C" or as the fourth cross-sectional shape D, D', D" or as fifth cross-sectional shape E, E', E" or as the sixth cross-sectional shape, F, F', F" or any other cross-sectional shape of higher order as long as the total inner volume along the tube decreases from the first and top cross-sectional shape to the last or bottom cross-sectional shape.

[0066] In some aspects, see figs. 4D and 5I, the first or top section has two tube windings with a cross-sectional shape A or A' or A" providing a larger inner volume along the first or top length section than the inner volume provided by the next or second section with two length sections having the second cross-sectional shape B or B' or B", which second section having two length sections with shape B or B' or B" has a larger inner volume than the next or third section with two length sections having the cross-sectional shape C, C', C", and this third section with two length sections with shape C, C', C" has a larger inner volume than the next or the fourth section with two length sections having the cross-sectional shape D, D', D", which fourth section with the two length sections having the cross-sectional shape D, D', D" has a larger inner volume than the next or the fifth section with three length sections having the cross-sectional shape E, E', E", and the fifth section having three length sections with the cross-sectional shape E, E', E" has a larger inner volume than the next or the sixth section with two tube length sections having the cross-sectional shape, F, F', F" providing a decrease of the total inner volume along the tube 11 from the first and top section to the last and bottom section in the direction of flow of refrigerant 1. In some aspects, the condenser 10 could have a fourth section with two length sections having the cross-sectional shape D, D', D" and a larger inner volume than the next or the fifth section with two instead of three length sections having the cross-sectional shape E, E', E". In some aspects, the condenser 10 could have each section with one or three or more length sections or a combination of different number of length sections having the corresponding cross-sectional shape A to F" as long as the inner volume decreases in accordance with or following the change of state of the refrigerant 1 when flowing from the first tube end 12 to the second tube end 13, i.e., the outlet of the condenser tube 11.

[0067] This forming by means of the tube forming machine 90, 90' and its rolls 91 incurs a length or section or part of transition TRA between the circular and tubular cross-sections with shape O as shown in figure 8 along the lengths LE 1 and LE 2 of the two tube ends 12 and 13 and forms the remaining length TL of the tube 11 with one or more of the length sections being formed with one or more varying and non-circular cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" (each TRA at straight lengths and at / along bends are encircled by dashed circles in figs. 2 to 4D, 5H, 5I, 6, and 7. However, in some aspects these transition areas TRA do not necessarily have to be located at any tube bends, one or more or all of these transition areas TRA could be arranged at straight tube parts if the inlet end 12 and / or outlet end 13 extended in a straight or more or less inclined fashion or if any bended or curved transition area TRA has a circular cross-section O being preferred when bending the tube 11 and / or if any straight transition area TRA is located between any of the lengths LE 1 and / or LE 2 of the first end 12 and / or the second end 13 as shown as an example in figs. 3C to 4D, 5H and 5I. Furthermore, in some aspects, the transition length(s) / section(s) TRA between the circular cross-sectional shapes O of the first and second tube ends 12, 13 and any last or second length section or third length section or fourth length section with other shape(s) could also be in some aspects as transition between the circular cross-sectional shapes of the first and second tube ends 12, 13 and any fifth or sixth or higher order length section with other shape(s). In other words, any length of the tube 11 between the first or last winding or coil of the condenser 10 and where the first end 12 ends and the second end 13 begins and / or where any transition area TRA (as shown in figs. 5H and 5I) begin(s) or end(s) may also be provided with one or more varying cross-sectional shapes as long as the total inner volume along the tube 11 from the first and top section to the last and bottom section in the direction of flow of refrigerant 1 is decreased. Any of the shown cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" and any combination of those cross-sectional shapes are achieved by pressing or actually squeezing the outside of the tube 11 by means of the rolls 91 more or less and - in some aspects - using rolls with planar surfaces and / or with different profiles or shapes between which the tube is pressed to form the tube.

[0068] According to the disclosure, the inventive condenser 10, i.e., its helically shaped tube 11, and the inner shape and / or inner circumference and / or inner surface of each tube winding and / or inner diameter SD i of the tube 11 comprises the inner surface 14 being flattened by the tube forming machine 90, 90' and its rolls 91 squeezing the tube 11 into a flat surface 14 extending along the tube length TL and along the tube height TH of the helically shaped tube 11 (see figs. 5A to 5I). The inner flat surface 14 faces radially inwards to be at least partly or substantially or fully in contact with the outer shell or mantle surface and / or outer circumference and outer diameter CD o of the container 3 when the condenser tube 11 is being or has been coiled around the outer shell of the container 3 as shown in figs. 1 and 2.

[0069] According to the disclosure, the helically shaped tube 11 also has an outer size and / or shape and / or surface and / or area with an outer circumference and / or outer diameter SD o (see figs. 4A, 4B, 4C, 5A, 5B, 5D and 6). In some aspects, the outer surface and / or area and outer circumference and / or diameter SD o of the tube 11 comprises an outer at least partly indented surface 15 (see figs. 5D (bottom view), and 5G) at or extending at least partly of fully along the tube length TL and tube height TH of the helically shaped tube 11 and along one or more length sections A", B", C", D", E", F") (see figs. 4C, 5D (bottom view), 5G, 5H, 5I and 6). In some aspects, the outer surface and / or area and outer circumference and / or outer diameter SD o of the tube 11 comprises one or more at least partly flat surfaces 15 extending at least partly of fully along the tube length TL and tube height TH of the helically shaped tube 11 and along one or more length sections A', A", B, B' (see figs. 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5I and 6). According to the disclosure, the outer partly indented and / or partly flat surface 15 of the tube 11 is configured to face radially outwards from the outer shell surface CD o of the container 3 when the tube is being wrapped or winded or has been winded around the container 3 by the forming machine 90 and its rolls 91. The helically shaped tube 11 has a tube width TW as shown in figs. 5B, 5C, 5D, 5H, 5I and 7, however all tubes according to the disclosure have of course a width and / or a diameter depending on its shape. The flat or flattened inner contact surface or area 14 of the tube 11 has a size with a length and / or height FI i , which is part of all embodiments of the tube 11, but only denoted in the two upper views in fig. 5B, and in all views of figs. 5C to 5H, even though figs. 5E to 5G only denotes this dimension of the inner flat contact surface 14 by arrows and straight lines to mark the position thereof, the same goes for fig. 5I as tube 11 is a physical entity. The - in some aspects - at least partly flat or flattened outer contact surface or area 15 of the tube 11 also has a size with a length and / or height FI o , which is part of at least one or some or all embodiments of the tube 11, but only denoted in the two upper views in fig. 5B, and in all views of figs. 5C, 5E, 5F and 5H, and in the two upper views of fig. 5D, even though figs. 5E to 5G only denotes this dimension of the outer surface 15 by arrows and straight lines to mark the position thereof, the same goes for fig. 5I as tube 11 is a physical entity. Preferably, the condenser tube 11 is made with both the inner surface 14 and the outer surface 15 at least partly flat or with an as great extension or area as possible to maximize the contact surface 14 against the shell of the container 3 and minimize the radial occupancy of space to make the tube as thin as possible while still enabling a sufficient function and flow of refrigerant 1 and as high heat exchange as possible and thereby maximizing the ability to apply more or thicker insulation around both the container 3 and the condenser 10 after manufacture. The pattern of the coiled condenser 10 in fig. 5H corresponds to the ones of figs. 3A and 4A, hence, these aspects are combinable and inherit each other's applicability, such as providing the condenser 10 of fig. 3A and / or fig. 4A with one or more any other combination of the cross-sectional shapes E and F or vice versa, as another example, by providing the condenser 10 of fig. 4C with one or more any other combination of for example the cross-sectional shapes E" and F" of fig. 5G and / or the cross-sectional shapes E and F in fig. 5I and 4D instead of the shown ones in fig. 4C and / or as complementary shapes therein or vice versa, the same combinability is applicable for all the shown condensers 10 as the tube 11 can be shaped in any combination of shapes A to I" and along different numbers of windings / coils and lengths along the tube as long as its inner volume decreases while its height TH increases as intended by applying the invention in the direction of refrigerant flow.

[0070] The condenser tube 11 has a length and / or height HL - as measured in the vertical direction of the center axis SCA for the condenser 10 - between where the transition areas or parts TRA of each of the lengths LE 1 , LE 2 and circular cross-sections O of the first and the second tube ends 12 and 13 start or end, respectively, and where the longitudinal length TL of the tube with the at least two length sections start or end, respectively, with different and varying and non-circular cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" when finally made and winded or coiled around the container 3 into the finished condenser 10 having a spiral or helical shape or helix with height HL as shown in figs. 2, 3A, 3B, 4A to 4D, 5H, 5I and 7. This total height HL is adaptable to different heights and depend also on how dense the pitch is for the condenser 10 as longer distance between the windings or threads or coils of the tube 11 means higher height while smaller distance means lower height HL. This height HL also depends on the actual length TL of the tube 11 and the additional lengths LE 1 and LE 2 of its ends 12 and 13 and the cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" along the length TL and the thickness of the tube walls and the thereby resulting inner volume of the tube 11 to actually provide a desired function and heat exchange when using a specific charge of refrigerant 1 in the heat pump system 100, in particular, achieving the optimized use of the small charge of propane being between 130 to 160 grams, preferably about 135 to 155 grams or more preferred about 140 to 154 grams or between 148 to 153 grams or most preferred about 152 or exactly 152 grams. In some applications, and depending on operational conditions in the heat pump system 100, such as flow rate and heat output and demand etc., the refrigerant charge or amount of propane in the condenser 10 may be between 20 grams to 100 grams.

[0071] In some aspects, the inner flat surface 14 of the helically shaped tube 11 of the condenser 10 is configured to extend along or cover or form part of an area of the height TH of the helically shaped tube 11 being of similar or same size or same area or being of different size or different area or larger size or larger area compared to the one of the outer flat surface 15. This is shown as the cross-sectional shapes A, B, C and D in fig. 5A; in the two lower or bottom views of cross-sectional shapes C and D in fig. 5B (even though these parameters are not drafted in those views, these shapes C and D correspond to the same ones in figs. 5A and 5C, the same goes for shape A in the middle view of fig. 5D as this shape corresponds to the same A-shapes in figs. 5A and 5C), and in figs. 5E, 5H and 5I where the heights or lengths FI i and FI o of the inner flat surface 14 and the outer flat surface 15, respectively, are of similar heights or lengths or about the same heights or lengths or the same heights or lengths and therefore substantially having about the same or the same areas. In figs. 5B (the two upper views showing the cross-sectional shapes A' and B'); 5D (top view showing a similar or the same cross-sectional shape A' as in the top view of fig. 5B), and in fig. 5F, the heights or lengths FI i and FI o of the inner flat surface 14 and the outer flat surface 15, respectively, are different, i.e., the height or length FI o of the outer flat surface 15 is less or smaller than the height or length FI i of the inner flat surface 14, whereby the inner flat contact surface 14 is larger than the outer flat surface 15. In fig. 5D (bottom view showing a differently shaped cross-section A" with an indent in the outer surface 15 making it non-flat) and in fig. 5G showing a similar shape or shapes A", B", C", D" with an indented outer surface 15, the height or length FI o of the outer flat surface 15 could be less or smaller or larger or the same as the height or length FI i of the inner flat surface 14. In some aspects, the one or preferably two or more at least partly varying and at least partly non-circular cross-sectional shapes of any length section A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" making up the length TL of the tube 11 has / have at least partly or fully a flat sided oval shape or at least partly or fully a flat sided elliptic shape or at least partly or fully a rounded rectangle shape or at least partly or fully a stadium shape as seen in figs. 5A to 5I.

[0072] According to the disclosure, the condenser 10 comprises a lengthwise at least partly varying cross-sectional shape of the tube 11, which at least partly varying cross-sectional tube shape A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" is configured to vary from where the first tube end 12 ends and the second tube end 13 starts in figs. 2, 3A, 3B, 4A, 4B, 4C, 5H, 5I and 7, such that the cross-sectional inner area and thereby the inner volume of the tube 11 is the smallest towards or at or closer to or closest to or adjacent the second tube end 13. In some aspects, this decrease of the inner volume of the tube 11 is linear while in some aspects non-linear and occurs in some aspects in smaller or larger steps in view of change of cross-sectional shape(s) A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" or in very small steps or in principle infinitely variable and very smooth transition along the length TL of the tube 11.

[0073] The helical shape of the tube 11 of the condenser 10 is in some aspects a helix with constant pitch (see figs. 3B and 4C). In some other aspects, the helical shape of the condenser tube 11 is a helix with varying pitch (see figs. 2, 3A, 4A, 4B, 4D, 5H and 5I). In some aspects, the helically shaped condenser tube 11 is a helix with any combination of any constant pitch and / or any varying pitch (not shown). In some aspects, the helical shape of the tube 11 of the condenser 10 is a helix with the distance between each turn or pitch being constant along a part or along the whole length or height HL and the axis SCA of the helix as seen in figs. 3B and 4C. In some aspects, the helical-shaped condenser tube 11 is a variable-pitch helix with a pitch varying or changing along at least a part of the length or height HL and axis SCA of the helix as shown in figs. 4A, 4B and 4D. In some aspects, the helical-shaped condenser tube 11 is a variable-pitch helix with a pitch varying or changing along the whole length or height HL and axis SCA of the helix as shown in figs. 4B and 4D. In some aspects, the helical-shaped condenser tube 11 is a variable-pitch helix having a first pitch varying or changing along at least a part of the length or height HL and axis SCA of the helix and a second pitch being constant along at least another part of the length or height HL and axis SCA of the helix. The helical shape of the condenser tube 11 is in some aspects a helix with the distance between the turns or pitch being larger along at least a first length section A, C, E of the helix along height HL and axis SCA of the helix and smaller along at least another or second or third or fourth or more length sections B, D, F of the helix along the height HL and axis SCA of the helix as seen in figs. 3A, 4A, 4B, 4D, 5H and 5I.

[0074] The condenser tube 11 making up the condenser 10 shown in figs. 3A and 4A is a helix with the distance between the turns or the pitch decreasing along a first length section A of the helix tube and along the height HL and center axis SCA to a second length section B of the helix tube along which second length section B or after this second length section B ends the pitch increases towards or to a third or fourth length section C, D of the helix tube along which third or fourth length section of the helix tube the pitch decreases again along the axis SCA. All of the described helixes of the condenser tube 11 making up the condenser 10 according to the disclosure could be combined, e.g., having a constant pitch in an intermediate length section B, B', B", C, C', C" while one or more other length sections have varying pitches and a first length section A, A', A" and / or a last length section D, D', D" has / have constant pitches. However, it is more preferred to have a denser pitch closer or at the bottom of the container 3 at the last length section(s) D, D', D", F, F', F", such as in figs. 5H and 5I, to provide an improved heat exchange where colder water 2 enters the container.

[0075] According to the disclosure, a method of manufacturing the condenser 10 for use in the heat pump system 100 is achieved by means of the tube forming machine 90 with the counter-rotating rolls 91 as shown in fig. 7. Firstly, the first or second tube end 12, 13 is introduced into the tube forming machine 90 and between the rolls 91. The feeding of the tube 11 starts at one of its ends 12 or 13 and the tube is fed through the machine 90 with the full-length TL before the other tube end is introduced therein and fed through. Then, the first tube end 12, 13 and the length TL of the tube 11 is fed through the tube forming machine 90 while forming the tube at least partly along at least a first length section A, A', A", B, B', B" and a second length section C, C', C", D, D', D" of the tube length TL into a varying cross-sectional shape and inner volume of the tube along its length TL and forming the tube length TL with at least one but preferably two flat and opposite surfaces 14, 15 along at least a part of one or preferably two or more or each tube length section A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F". In some embodiments, the tube length TL is formed with one flat inner surface 14 and one non-flat or at least partly indented outer surface 15 as opposite surfaces along at least a part of one or two or more tube length sections A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F". Then, the tube 11 is ejected or fed out from the forming machine 90, and winded or coiled with each tube length section A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" into a helically shaped tube 11 around the container 3 with at least one flat inner surface 14 facing radially inwards forming an inner flat contact surface 14 at least partly or substantially or fully in contact with a first area of the outer shell and / or outer circumference and / or envelope surface CD o of the container 3.

[0076] According to the disclosure, the method of manufacturing the condenser 10 comprises forming the tube 11 - by the tube forming machine 90, 90' and its rolls 91 - at least partly along at least one of the tube length sections of the tube length TL after the length LE 1 of the first tube end 12 has firstly been fed past the rolls 91 in the tube forming machine 90 or the length LE 2 of the second tube end 13 has firstly been fed past the rolls 91 in the tube forming machine 90' (see fig. 7) into one varying cross-sectional shape A, A', A" with one varying inner volume, and forming the tube 11 at least partly along at least another tube length section of the tube length TL into another varying cross-sectional shape B, B', B", C, C', C", D, D', D" with another varying inner volume being smaller than the varying inner volume of the other and first and former tube length section A, A', A" to provide the decreasing total inner volume along the tube 11 from the first and top section to the last and bottom section for the refrigerant 1 to flow through.

[0077] In some aspects, the method of manufacturing the condenser 10 further comprises winding or coiling each of the length sections A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" along the tube length TL of the tube 11 into the helically shaped tubular condenser 10 around the container 3 with the inner flat contact surface 14 always facing radially inwards and being at least partly or substantially or fully in contact with an area of the outer shell CDo of the container 3 being different from any area of the shell of the container that any other tube length section is winded or coiled around.

[0078] In some aspects, the method of manufacturing the condenser 10 also comprises forming, by means of the tube forming machine 90, 90', at least a first tube length section of the tube length TL of the tube 11 into a first varying cross-sectional shape A, A', A", B, B', B", C, C', C", D, D', D" with a first varying inner volume along the first half of the length TL of the tube 11 and forming at least a second tube length section into a second varying cross-sectional shape C, C', C", D, D', D", E, E', E", F, F', F", G (G', G" not shown), H (H', H" not shown), I (I',I" not shown) with a second or last varying inner volume along the second half of the tube length TL of the tube 11, which second or last varying inner volume is smaller than the first varying inner volume of the first tube length section(s) A, A', A", B, B', B" and / or any intermediate sections C, C', C", D, D', D".

[0079] In some aspects, the method of manufacturing the condenser 10 further comprises feeding a first tube end 12, 13 into and past the rolls 91 through the tube forming machine 90, 90' and ejecting the first tube end from the forming machine without changing the form of the first tube end, and feeding the second tube end 12, 13 into and past the rolls 91 through the tube forming machine 90, 90' and ejecting the second tube end from the forming machine without changing the form of the second tube end.

[0080] In some aspects, the method of manufacturing the condenser 10 comprises forming, by means of the tube forming machine 90, 90', the length TL of the tube 11 between the end of the length LE 1 of the first tube end 12 and the start of the length LE 2 of the second tube end 13 with at least one or preferably at least two partly varying cross-sectional shapes C, C', C", D, D', D", E, E', E", F, F', F" and at least one or preferably at least two partly varying inner volumes and with at least two flat and opposite surfaces 14, 15 along at least a part of the tube length TL, such that the at least partly varying inner volume(s) decrease(s) after the length LE 1 of the first tube end 12 ends towards and until the length LE 2 of the second tube end 13 starts.

[0081] The graph or plot in fig. 9 illustrates the refrigerant charge distribution (on the y-axis) in the condenser 10 along the condenser tube length TL and along the varying cross-sectional shapes A, B, C, D, E, F, G, H and I (on the x-axis). The x-axis represents the position along the condenser tube 11 (from shape A (applicable to shapes A', A") with lowest height TH (and widest width TW) to shapes B, C, D, E, F, H and / or I (applicable to shapes B', B", C', C", D', D", E', E", F', F" (or shapes H', H" and / or I', I" not shown)) with increasing and / or greatest heights TH (and decreasing and / or smallest width(s) TW)), with the refrigerant entering at x = 0 in length (via inlet 12 having tube shape O (circular cross-sectional shape of the condenser tube 11)) and exiting at / through shape F or G or H or I etc. (with smallest width(s) TW) via the outlet 13. Vertical dotted lines indicate the locations where internal volume is reduced, i.e., where the tube 11 changes cross-sectional shape from O to A (along / after length LE 1 of inlet 12 and / or before / in / after TRA / bends) or A to B or B to C or C to D or D to E or E to F or F to G or G to H or H to I (or I to J - (shape J, J' or J" is not shown)) and lastly from C / D / E / F / G to O again and vice versa (before / in / after TRA / bends and / or before / along length LE 2 of outlet 13 seen as squeezing points or shape transition areas or length sections of the tube 11). The graph of fig. 9 clearly shows that, without these flattened or squeezed tube length sections of the condenser 10 in the direction of the width TW, the refrigerant charge would increase exponentially as in prior art condensers. In contrast to prior art solutions, this optimized condenser design according to the disclosure - and as achieved with all of the designs of the condenser 10 shown exemplified in figs. 2 to 4D, 5H, 5I and 7 - flattens the refrigerant charge curve, demonstrating a more controlled and efficient refrigerant charge distribution to enable good and improved performance of the heat exchange system even though the refrigerant charge is below 150 to 155 grams or about 151 to 153 grams compared to prior art ones.

[0082] In fig. 5I (view A - A), the last shapes E and F actually have an inner width TW providing an inner volume smaller than the upper or upstream shapes even though fig. 5I is not showing this as clearly as the upper shapes A to D do. The last or lowest shapes E and F in fig. 5I are actually similar or the same or at least equivalent to the last or lowest shapes E and F in fig. 5H clearly showing the existence of an inner volume in higher or greater magnification.NOMENCLATURE

[0083] 1: Refrigerant in the form of propane. 2: Water in fluid / viscous / liquid and / or gas / vapor form. 3: Container of metal for containing water 2. 4: Inlet of (non-heated / cold) water into the container 3. 5: Outlet of (hot / hotter / warm / warmer) water out of the container 3. 10: Heat exchanger / Heat exchanging device or condenser. 11: Helically wound tube of condenser 10 12: First tube end of condenser 10. 13: Second tube end of condenser 10. 14: Inner flat surface of the tube 11. 15: Outer flat surface of the tube 11. 16: Pipe connection between inlet 12 and the heat pump system 100. 17: Pipe connection between outlet 13 and the heat pump system 100. 90, 90': Tube forming machine with rolls. 91: Tube forming rolls of the tube forming machine 90, 90'. 100: Heat pump system. 110: Compressor. 120: Evaporator. 130: Thermal expansion valve 140: Evaporator outlet temperature measurement for superheat control. C, C', C", D, D', D", E, E', E", F, F', F", G, G', G", H, H', H", I, I', I": Different cross-section(s) of the tube 11 along a part or section or parts or sections of its length TL or along its full length TL and / or along two or more length sections of the tube 11. SCA: Center axis of the helical-shaped tube 11. CCA: Center axis of the container 3. FL i : Size / Length / Height of the flat / flattened inner contact surface / area 14 of tube 11. FL o : Size / Length / Height of the flat / flattened outer surface / area 15 of tube 11. HL: Length / Height of the helical shape / helix part of the tube 11. LE 1 : Length of the first tube end 12. LE 2 : Length of the second tube end 13. RD: Adjustable distance between rolls 91 of the tube forming machine 90. SD i : Inner size and / or shape and / or diameter of the condenser tube 11. SD O : Outer size and / or shape and / or diameter of the condenser tube 11. CD o : Outer size and / or shape and / or diameter of the water container 3. TRA: Transition length(s) / section(s) / bend(s) with shape O between changing cross-sectional shapes. TL: Length of the tube 11. TH: Vertical height of the tube 11. TW: Horizontal width or thickness of the tube 11.

Examples

Embodiment Construction

[0049]The present disclosure will now be described with reference to the accompanying drawings 1 to 9, in which preferred example aspects of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed aspects. The disclosed aspects are provided to fully convey the scope of the disclosure to the skilled person. All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

[0050]In particular, figures 5A, 5C, 5H and 5I show - in perspective - enlarged cross-sectional parts or sections and / or shapes of the invention, a tubular condenser 10, in cutout views (to the right in figs. 5H and 5I) corresponding to the cutout views in figs. 4A, 4D and 5A for enhanced overview of dimensions of these entities not shown by arrows and denotations in figs. 4A, 4D and 5A (such as ...

Technical field

[0001] The present disclosure relates to a heat exchanger for use in a system for heating water in a container by means of a condenser comprising a tube to let through a flow of a refrigerant in gas or vapor and fluid / liquid form. The present disclosure also relates to a method of manufacturing a condenser comprising a tube for use in a heat exchanger. More specifically, the disclosure relates to a heat exchanger for use in a heat pump system, a condenser for use in the heat exchanger of the heat pump system, the condenser comprising a tube configured to enable heat exchange between a refrigerant in the condenser tube and water in a container, and a method for manufacturing said tubular condenser.Background art

[0002] An example of a prior art condenser is disclosed in US 2025 / 0012483 A1 using a tube wrapped or coiled around a water tank for heat exchange with the water in the tank.

[0003] Due to the concern for the effects of the release and / or leakage of Hydrofluorocarbons (HFC) refrigerants on the global environment caused by the high global warming potential of these substances, there is a large interest in the world, and particularly in Europe, for the use of natural refrigerants, as hydrocarbons, instead of HFCs.

[0004] A problem with the solutions of the prior art, using different kinds of hydrocarbons as refrigerants to heat and / or cool, e.g., food products and / or tap water, such as in refrigerators, freezers, water heaters or the like, is that the leakage of such refrigerants from pipe couplings etc. may incur risk of explosions and / or fires as hydrocarbons are inflammable substances. Examples of known hydrocarbons used in heat exchange processes are propane (C 3 H 8 ) being used in refrigeration cycles and as a refrigerant in heat pumps, isobutane and butane (C 4 H 10 ).

[0005] There is thus a need for improving devices using hydrocarbons as refrigerants, such as propane, for heat exchange and the manufacturing process of such devices.Summary

[0006] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above-mentioned problem / -s. According to a first aspect there is provided a condenser for use in a heat pump system for exchanging heat between a refrigerant and water in a container, the condenser comprising a tube through which the refrigerant is configured to flow via a first tube end being a refrigerant inlet of the condenser and a second tube end being a refrigerant outlet of the condenser, wherein the tube of the condenser has a length and a height in the vertical direction, which length at least partly comprises a varying cross-sectional shape along one or more length sections having at least one or more different and / or one or more similar and / or one or more of the same varying cross-sectional shapes between the two tube ends, and the tube is configured with a helical or spiral shape having an inner size and / or inner shape and / or inner circumference and / or inner diameter being adapted to the outside and / or outer size and / or outer surface and / or shell and / or outer shape and / or outer circumference and / or outer diameter of the container, wherein the inner shape and / or inner circumference and / or inner diameter of the helically shaped tube of the condenser comprises an inner flat surface along the length and height of the helically shaped tube, the inner flat surface being configured to face radially towards and be at least partly or substantially or fully in contact with the outer shell surface of the container, characterized in that the height of the helically shaped tube is increasing along at least two length sections in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0007] According to some aspects, the helically shaped tube of the condenser is configured with an outer size and / or outer shape and / or outer surface and / or outer area having an outer circumference and / or outer diameter comprising an outer at least partly indented and / or at least partly flat surface along the length and height of the helically shaped tube, the outer partly indented and / or partly flat surface being configured to face radially outwards from the outer surface or shell of the container.

[0008] According to some aspects, the height of the helically shaped tube is increasing along at least two, three or more length sections from lower to greater heights in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0009] According to some aspects, the inner flat surface and / or the outer surface of the helically shaped tube of the condenser is / are configured to extend along a substantial part of the height of the helically shaped tube or is / are configured to extend along a substantial part of the full height of the helically shaped tube or is / are configured to extend along almost or nearly the whole full height of the helically shaped tube.

[0010] According to some aspects, the tube of the condenser comprises at least two length sections having at least one partly varying cross-sectional shape with partly varying inner volume differing from each other's cross-sectional shapes and inner volumes and / or differing from any cross-sectional shape and inner volume of one or more of the other length sections of the tube in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0011] According to some aspects, the tube of the condenser comprises at least two length sections of which each has at least one partly varying cross-sectional shape with partly varying inner volume differing from each other's cross-sectional shapes and inner volumes and / or differing from any cross-sectional shape and inner volume of one or more of the other length sections of the tube along the length of the tube with at least two length sections upstream at least a third or fourth or fifth or last length section in the direction of flow of the refrigerant having lower heights and larger inner volumes than at least the downstream third or fourth or fifth or last length section closest to the outlet.

[0012] According to some aspects, the inner flat surface and the outer surface of the helically shaped tube of the condenser are arranged opposite each other and are flattened to different extents or to similar extent or the same extent along the height of the helically shaped tube.

[0013] According to some aspects, the inner flat surface of the helically shaped tube of the condenser is configured to extend along or cover a greater extent of the height of the helically shaped tube compared to the outer surface of the helically shaped tube.

[0014] According to some aspects, the tube of the condenser is configured to be a separate detail / item / part and detachably arranged or coiled around the outside of the container in the heat pump system.

[0015] According to some aspects, the length of the tubular condenser comprises at least two length sections, a first length section with a first at least partly varying cross-sectional shape and a first at least partly varying inner volume and a second length section with a second at least partly varying cross-sectional shape and a second at least partly varying inner volume, which first at least partly varying inner volume is larger than the second at least partly varying inner volume in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0016] According to some aspects, the length of the tube of the condenser comprises at least a third or fourth or more length sections with at least partly varying third or fourth or more cross-sectional shapes providing at least partly varying third or fourth or more inner volumes, respectively, being smaller than the first at least partly varying inner volume and / or the second at least partly varying inner volume of the first and / or second length sections in the direction of flow of the refrigerant from the first tube end to the second tube end.

[0017] According to some aspects, the lengthwise at least partly varying cross-sectional shape of the tube of the condenser is configured to vary between the first tube end and the second tube end, which at least partly varying cross-sectional inner shape and area is configured to provide an inner volume that at least partly decreases along the length of the tube in the flow direction of the refrigerant to the second tube end.

[0018] According to some aspects, the length of the tube of the condenser comprises at least two length sections providing a first length part forming half of the full length of the whole tube and a second length part forming the other half of the full length of the whole tube, which first length part comprises a larger inner volume than the second length part of the length of the tube.

[0019] According to some aspects, the helical or spiral shape of the tube of the condenser is configured as a helix with constant pitch or varying pitch and / or as a helix with any combination of any constant pitch and / or any varying pitch.

[0020] According to some aspects, the helical or spiral shape of the tube of the condenser is configured as a helix with the distance between each turn or pitch being constant along a part or along the whole length or height and the axis of the helix or is configured as a variable-pitch helix with a pitch varying or changing along at least a part of the length or height and axis of the helix or is configured as a variable-pitch helix with a pitch varying or changing along the whole length or height and axis of the helix or is configured as a variable-pitch helix having a first pitch varying or changing along at least a part of the length or height and axis of the helix and a second pitch being constant along at least another part of the length or height and axis of the helix.

[0021] According to some aspects, the helical or spiral shape of the tube of the condenser is configured as a helix with the distance between the turns or pitch being larger along at least a first length section of the helix along the height and axis of the helix and smaller along at least another or second or third or fourth length section of the helix along the height and axis of the helix.

[0022] According to some aspects, the tube of the condenser is configured as a helix with the distance between the turns or the pitch decreasing along a first length section of the helix tube to a second length section of the helix tube along which second length section of the helix tube the pitch increases to a third or fourth length section of the helix tube along which third or fourth length section of the helix tube the pitch decreases again along the axis of the helix.

[0023] According to some aspects, one or more of the length section(s) of the helical or helix or spiral shape of the tube of the condenser is(are) provided with the same distance between the turns or the same pitch and / or which length sections of the helix is a combination of one or more length sections having a constant pitch and one or more length sections having an at least partly varying pitch or which length sections of the helix is a combination of one or more length sections having a decreasing pitch and one or more length sections having an increasing pitch.

[0024] According to some aspects, the helical or spiral shape of the tube of the condenser is provided with at least one length section arranged closer to or at or adjacent or ending at or where the second tube end begin as seen in the direction of flow of refrigerant, which at least one length section has a varying pitch decreasing along the axis of the helix forming a denser or the densest pitch closer to or at or adjacent or ending at where the second tube end begin.

[0025] According to some aspects, the first tube end being the refrigerant inlet of the condenser and the second tube end being the refrigerant outlet of the condenser have lengths with cross-sectional shapes that are not changed or similar to each other's cross-sectional shapes or have the same cross-sectional shapes and / or sizes and / or diameters.

[0026] According to some aspects, each of the first tube end and the second tube end of the condenser has a circular cross-sectional shape along the length.

[0027] This makes the coupling of the condenser, i.e., the tubular ends of the condenser, to the heat pump system easier while providing sufficient sealing as the cross-sections of the respective ends do not change and / or is circular therefore enabling using standard tube couplings or connecting means.

[0028] According to some aspects, the length of the tube comprises at least two length sections, each length section having one or more at least partly varying and at least partly non-circular cross-sectional shapes along at least a part of the tube length between the first and the second tube ends.

[0029] According to some aspects, the one or more at least partly varying and at least partly non-circular cross-sectional shapes of any length section of the length of the tube has / have at least partly or fully a flat sided oval shape or at least partly or fully a flat sided elliptic shape or at least partly or fully a rounded rectangle shape or at least partly or fully a stadium shape.

[0030] According to some aspects, the refrigerant comprises propane or is propane, C 3 H 8 .

[0031] This provides an improved and more robust heat exchange and control thereof by usage of a refrigerant with excellent thermodynamic properties and ability to efficiently transfer heat and easy availability for a relatively low cost.

[0032] According to some aspects, the one or more at least partly varying and at least partly non-circular cross-sectional shapes of at least one or preferably at least two or more or all length sections of the length of the tube has / have the inner flat surface forming a straight plane extending in parallel with the center axis of the helical tube and the outer surface forming an at least partly flat and straight plane opposite and in parallel with the inner flat surface and extending along the tube in the same way as the inner flat surface.

[0033] According to some aspects, the one or more at least partly varying and at least partly non-circular cross-sectional shapes of at least one or preferably at least two or more or all length sections of the length of the tube has / have the inner flat surface forming a straight plane extending in parallel with the center axis of the helical tube and the outer surface forming an at least partly non-straight or non-flat surface or at least partly radially inwards extending or indented surface.

[0034] Any of the aspects above and below provides an optimized use of a small charge of a hydrocarbon, e.g., a propane charge being between 130 to 160 grams, preferably about 135 to 155 grams or more preferred about 140 to 154 grams or between 148 to 153 grams or most preferred about 152 or exactly 152 grams. Any of the aspects above and below provides reducing the risk of combustion due to leakage of propane while still providing an efficient heat exchange between the refrigerant in the tube and the water in the container due to the combination of increased contact area between the inside of the tube and the outer shell of the container and the decreased outer radial "size" or occupied external space by means of the tube due to the decreased radial extension of the outer side of the tube giving room for more insulation around the container and the tube to further enhance the desired direction of the heat flow towards and into the water inside the container.

[0035] Any of the aspects above and below provides the ability to optimize the refrigerant quantity across the heat exchanger, while minimizing the overall pressure losses - and more uniform pressure profile across the condenser - and increasing the heat transfer area.

[0036] Any of the aspects above and below provides the ability to assemble, manufacture and operate a heat pump system with improved efficiency and reduced operating, maintenance and manufacturing costs.

[0037] Any of the aspects above and below provides an ability to use a smaller charge of a hydrocarbon, such as propane, as a refrigerant as the charge of a combustible hydrocarbon is one of the restricting criteria when designing solutions of heat exchange systems used in households, i.e., the total amount of refrigerant, measured by weight, being the charge of a hydrocarbon, e.g., propane, should not exceed about 150 - 152 grams in said system to reduce the risk of combustion if leakage of hydrocarbon occurs and also enables this inventive solution to fulfil regulatory demands in as many jurisdictions as possible, e.g., in Europe.

[0038] Any of the aspects above and below reduce the risk of having a heat pump with refrigerant charge lower than needed, that would lead to a poor heat pump efficiency.

[0039] According to a second aspect, there is provided a method of manufacturing a condenser for use in a heat pump system to exchange heat between a refrigerant and water (in a container, the condenser comprising a tube with two tube ends and a length therebetween for letting the refrigerant through and a height in the vertical direction, the method comprising introducing a first tube end into a tube forming machine before a second tube end is introduced therein, feeding the first tube end and the length of the tube through the tube forming machine and forming the tube at least partly along at least a first section and a second section of the tube length into at least one or more varying cross-sectional shapes and with at least two flat and opposite surfaces or with one inner flat surface and one at least partly indented and / or at least partly flat outer surface along at least a part of each tube length section, winding or coiling each tube length section into a helically shaped tube around the shell of the container with the flat inner surface facing radially inwards forming an inner flat contact surface at least partly or substantially or fully in contact with a first area of the outer shell of the container, and increasing the height of the helically shaped tube along at least two length sections from lower to greater heights in the direction from the first tube end to the second tube end.

[0040] According to some aspects, the method comprises winding or coiling each of the length sections into the helically shaped tube around the container with the inner flat contact surface facing radially inwards and at least partly or substantially or fully in contact with an area of the outer shell surface of the container being different from any outer area or shell area of the container that any other tube length section is winded or coiled around.

[0041] According to some aspects, the method comprises forming, by means of the tube forming machine at least a first tube length section into a first varying cross-sectional shape and a first varying inner volume of the first half of the length of the tube and forming at least a second tube length section into a second varying cross-sectional shape with a second varying inner volume of the second half of the tube length, which second varying inner volume is smaller than the first varying inner volume of the first tube length section.

[0042] This provides an easier manufacturing of the tube of the condenser by not having to form or reshape the whole length of the tube while also simplifying the coupling of the condenser ends to the heat pump system and enables achieving an improved and more secure sealing as the cross-sections of the respective ends do not change and / or is circular therefore enabling using standard tube couplings or connecting means.

[0043] Hence, by increasing the height of the condenser tube along at least two length sections of the tube and actually decreasing the tube width along at least the same two or more length sections at the same time in the flow direction of the refrigerant - primarily decreasing the inner width and increasing the inner height of the tube even though the outer and the inner widths / heights of the tube correlate but this correlation of course depends on the thickness of the material of the tube as the inner width and inner height factually form / enclose / define the inner volume of the tube - in accordance with where the refrigerant has higher density (closer to the outlet of the condenser) and having a lower height and greater width of the tube or a wider tube where the refrigerant has lower density (at or in or closer to the inlet of the condenser) seen in the flow direction of the refrigerant provide three improvements - see below and the disclosure - in performance of the inventive condenser compared to prior art condensers. In other words, these three performance improvements of the inventive condenser are achieved by having a greater / higher / larger internal volume (lower degree of squeezing of the condenser tube closer to the tube inlet) when the refrigerant enters the condenser in gaseous state and a smaller or lower / reduced / decreased internal volume (higher degree of squeezing of the condenser tube closer to and / or adjacent and / or at and / or just before and / or after the tube outlet) when the refrigerant leaves the condenser in liquid state: Reduction of refrigerant charge: When the refrigerant enters the condenser, the refrigerant is in a gaseous state with relatively low density. This initial part or section of the condenser is therefore not particularly sensitive to refrigerant charge. However, as condensation progresses, the refrigerant transitions into a liquid state, and the density of the refrigerant increases significantly, often by a factor of up to 10 compared to the inlet of the condenser, i.e., the tube inlet. This means that length sections after the inlet, in particular the latter part(s) or section(s) of the condenser downstream the inlet, where the refrigerant is mostly liquid, contributes disproportionately to the total system charge. By increasing the height of the condenser tube from the inlet on (by applying a more aggressive squeezing of the tube, i.e., reducing also the width and thereby internal volume) specifically in the later length section(s), in particular in the final length section(s) of the condenser tube, the most charge-sensitive zone of the heat pump system and the condenser is effectively target. This condenser design approach leads to a substantial reduction in the overall refrigerant charge required compared to prior art condensers visualized in figure 9. Reduction of pressure drops: Although the refrigerant density increases significantly in the liquid phase, the velocity of the refrigerant when flowing from the inlet decreases substantially. This lower velocity of the refrigerant allows for a more aggressive increase of the height of the condenser tube along at least two length sections (e.g., by squeezing of the condenser tubing), preferably in and along the latter length sections-where the refrigerant is mostly liquid-without causing excessive pressure drops across the system. This design strategy of the condenser takes advantage of the flow characteristics of the refrigerant: high density but low velocity in the liquid phase means that flow resistance remains manageable even when the internal volume is reduced in the direction of the refrigerant flow along the tube. As a result, the condenser geometry is optimized to reduce refrigerant charge to enable using such low amount of refrigerant and also enhances heat transfer without compromising system performance due to pressure losses as this inventive condenser design strategically applies volume reductions only where they are most effective and least detrimental to flow dynamics when using such a low refrigerant charge below 150 to 155 grams or about 152 to 153 grams. Increase of heat transfer area and improvement of heat transfer coefficient (HTC): The condenser design according to the disclosure enables an adequate heat transfer area by allowing for an increased number of tube windings. This is made possible by the simultaneous reduction in refrigerant charge and pressure drop, which removes previous design constraints and permits a more optimized winding and tube coil layout. Additionally, as the tube is provided with an increased height TH along at least two length sections, preferably more, along the condenser tube in the direction of the refrigerant flow, the flat inner tube surface in contact with the tank also increases enhancing thermal conduction, particularly in the lower part or sections of the condenser. While the heat transfer coefficient (HTC) is generally higher in the two-phase and gaseous regions for the refrigerant, the disclosed condenser design improves HTC even in the liquid phase of the refrigerant. This is achieved through a higher degree or increase of tube height TH (e.g., by squeezing the condenser tube), which increases the inner tube surface contact with the tank and turbulence, without significantly increasing pressure drop. The result is a more efficient and balanced heat exchange process across all phases of the refrigerant by use of this condenser design.

[0044] The invention provides several key advantages that distinguish the disclosed condenser from existing solutions in prior art systems with heat pumps and condensers by enabling the use of low-charge propane systems without compromising performance (main advantage); improves heat pump efficiency (COP) at significantly reduced refrigerant volumes and increases adequate heat exchange area despite reduced internal volume along the condenser in the direction of refrigerant flow.

[0045] The invention also addresses problems not solved by prior art condensers by addressing the challenge of using flammable refrigerants with strict charge limits; introducing a condenser design that balances refrigerant volume reduction with performance optimization; minimizing pressure losses while preserving heat transfer capabilities and provides a scalable and cost-effective solution for next-generation heat pumps using natural refrigerants at low charge, while maintaining high performance(s) by using the higher heat transfer coefficient (HTC) in liquid phase together with higher velocity in the condenser tube with increased (greater) height TH and narrower or thinner width TW towards and at the condenser tube outlet compared to lower velocity closer to and at / in the condenser tube inlet and a greater heat transfer area in the later and / or latest condensing phase of the refrigerant towards and closer to and at the end of the condenser, i.e., towards and at the outlet.

[0046] Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the devices described or steps of any method described since such devices and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular aspects only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claims, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements or entities unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit / device / tube / condenser" or "the unit / device / tubes / condensers" may include one, two or several units and / or devices / tubes / condensers, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings do not exclude other elements or steps of a process or method. According to the disclosure, entities or parts or details without reference numerals and / or denoted as X or X' or X" and / or Y or Y' or Y" are meant to comprise and / or include at least similar shapes and / or functions and / or the same shapes and / or functions as other corresponding entities having similar reference numerals or other denotations, i.e., each and every entity denoted with reference numerals are at least functionally, or even in some embodiments structurally, interchangeable with each and every entity having no reference numerals. This means that entities having reference numerals or other denotations, such as X or X' or X" and / or Y or Y' or Y" above or below, are provided with either exactly the same features or similar or very similar and equally usable and interchangeable feature or comprises at least one or more or all of the same features as the entities without reference numerals and / or entities being denoted as X or X' or X" and / or as Y or Y' or Y", which features could be structural and / or functional features.

[0047] Terminology -- The terms "vertical / horizontal" or "upstanding / laying" are to be interpreted as a relative positioning of entities in relation to the horizontal or vertical plane but not necessarily in directions and / or positions that are exactly aligned with or in these planes and may deviate somewhat from these directions and / or planes within applicable tolerances as understood by a skilled person within the technical field while still being defined as horizontal or vertical or upstanding or laying or extending horizontally or vertically.Brief descriptions of the drawings

[0048] The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example aspects / embodiments of the present disclosure, when taken in conjunction with the accompanying drawings. Figure 1 shows - schematically - a heat pump system according to an aspect of the present disclosure. Figure 2 shows a water container - in a side view - with a tubular condenser wrapped around the water container for use in a heat pump system according to an aspect of the present disclosure. Figure 3A shows - in a perspective view - a tubular condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 3B shows - in a perspective view - a tubular condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 3C shows - in a perspective view - a tubular condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 4A shows - in a side view - a tubular condenser, e.g., as in fig. 3A, separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 4B shows - in a side view - a tubular condenser, e.g., similar to the one in fig. 3B, separately for heat exchange in a heat pump system according to an aspect of the disclosure. Figure 4C shows - in a side view - a tubular condenser, e.g., similar to the one in fig. 3B, separately for heat exchange in a heat pump system according to an aspect of the disclosure. Figure 4D shows - in a side view - a tubular condenser, e.g., as in fig. 3C, separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 5A shows in perspective enlarged cross-sectional parts or sections and / or shapes of the tubular condenser in four cutout views corresponding to the cutout views in fig. 4A. Figure 5B shows - in perspective - enlarged cross-sectional parts or sections and / or shapes of an alternative tubular condenser in four cutout views, the two upper cutout views correspond to the two upper cutout views in fig. 4B, and the two lower cutout views correspond to the two lower cutout views in fig. 4A according to an aspect of the disclosure. Figure 5C shows - in perspective - enlarged cross-sectional parts or sections and / or shapes of the tubular condenser in cutout views corresponding to the cutout views in figs. 4A and 5A. Figure 5D shows - in perspective - enlarged cross-sectional parts or sections and / or shapes of another tubular condenser in three cutout views of which the top cutout view corresponds to the top cutout view in fig. 4B and the top cutout view in fig. 5B while the middle cutout view corresponds to the top cutout views in figs. 4A, 5B and 5C, and the bottom cutout view of fig. 5D corresponds to the top cutout view in fig. 4C and the view in fig. 5G according to an aspect of the present disclosure. Figures 5E to 5G show - in side views - different enlarged cross-sectional parts or sections and / or shapes being applicable for use in a condenser separately and / or in any combination in similar ways or the same way or in other ways of combinations as shown in the ones of figs. 5A to 5D. Figure 5H shows - in a side view - a tubular condenser separately for heat exchange in a heat pump system and - in perspective - enlarged cross-sectional parts or sections and / or shapes of this exemplary tubular condenser in six cutout views according to an aspect of the present disclosure. Figure 5I shows - in a side view - the condenser of fig. 4D separately for heat exchange in a heat pump system and - in perspective views to the right - enlarged cross-sectional parts or sections and / or shapes of this exemplary tubular condenser in thirteen cutout views according to the cutout A - A (main difference between the condensers of figs. 5I and 5H is the vertical height and pitch at / for the tube winding or coiling with shape E, the principle and dimensional parameters and varying shapes of the condenser tube, such as vertical height, width (inner / outer width), inner and outer surfaces are the same or close or very close even if not all dimensions and surfaces in fig. 5I are visualized by numerals and arrows and lines compared to fig. 5H as long as the vertical tube height is larger or the largest (and the width is smaller or the smallest) for the last shape(s) compared to the first shape) according to an aspect of the present disclosure. Figure 6 shows - in a top view from above - a condenser separately for heat exchange in a heat pump system according to an aspect of the present disclosure. Figure 7 shows schematically manufacturing of a tubular condenser by forming the tube around a container according to an aspect of the present disclosure. Figure 8 shows an enlarged cross-section view of a part or section and / or shape being applicable and used in any condenser of figs. 1 to 4D, 5H, 5I, 6 and 7 along or at a tube end or a length or section or a shape transition part as shown at or adjacent or in or as parts of bends or as the whole bends including any tube length closest to and / or adjoining and / or before and / or after each bend encircled by dashed circles in figs. 2 to 4D, 5H, 5I, 6 and 7) and / or along lengths of the two tube ends (as shown in figs. 2 to 4D, 5H, 5I, 6 and 7) with a circular and tubular cross-section according to an aspect of the present disclosure. Figure 9 illustrates refrigerant charge distribution (y-axis) in the condenser along the condenser tube length and along the varying cross-sectional shapes of the tube (x-axis) according to the present disclosure. Detailed description

[0049] The present disclosure will now be described with reference to the accompanying drawings 1 to 9, in which preferred example aspects of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed aspects. The disclosed aspects are provided to fully convey the scope of the disclosure to the skilled person. All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

[0050] In particular, figures 5A, 5C, 5H and 5I show - in perspective - enlarged cross-sectional parts or sections and / or shapes of the invention, a tubular condenser 10, in cutout views (to the right in figs. 5H and 5I) corresponding to the cutout views in figs. 4A, 4D and 5A for enhanced overview of dimensions of these entities not shown by arrows and denotations in figs. 4A, 4D and 5A (such as FI i , FI o , TH (inner and / or outer height in the vertical direction) and TW (inner and / or outer width in the horizontal direction) or in figs. 5C and 5I (such as SD i and SD o shown in figure 6) but which dimensions are applicable to and - in principle - exist in all corresponding entities as referred to in the disclosure and on the drawings including figures 5I and 8 (even though the height and width of shape O is of course the same as it is circular) where the similar or the same entities and / or cross-sectional shapes are shown, see also the nomenclature for clarification of abbreviations, to not having figures showing too many numerals and arrows etc. making them difficult to clearly view. This is due to the fact that each of the applicable cross-sectional shapes used for the tubular condenser 10 of course physically has an inner and outer height, an inner and outer width and thickness even though at least one or two or more or some or all cross-sectional shapes of the tubular condenser may be or are at least partly shaped differently, such as the circular shape O.

[0051] Figure 1 shows a heat pump system 100 according to the disclosure. The heat pump system 100 comprises a container 3. The container 3 is shown to the far right in fig. 1. The container 3 is configured to contain water 2 to be let into the container 3, e.g., by pumping via electrically driven pumps or the like as is known to the skilled person, for heating via an water inlet 4 for non-heated or cold water, and to let the water 2 out of the container after being heated by being pumped out, e.g., as hot water 2 for use when bathing or to shower or for heating of a residential house or a swimming pool via a water outlet 5. The container 3 is preferably made of metal. The control of the pumping and the heating of the water 2 inside the container 3 are provided by use of a suitable number and types of sensors, thermostats, water pumps, such as circulating pumps, valves, tubing etc. besides the components used in the heat pump system 100. The components and functions for handling the water 2 are commonly known by a skilled person, and which water system components are operatively connected to each other and the heat pump system 100 and control units (not shown). Moreover, power is of course provided to drive all the necessary equipment and component as desired in both the water handling system and the heat pump system 100. The working principle of the heat pump system 100 shown in fig. 1 concerns using a heat pump being a device that transfers heat from one place to another by means of a circulating refrigerant 1 used as a medium. The heat pump system 100 as shown in fig. 1 comprises at least four main components: a compressor 110, an evaporator 120, one or more condensers 10 comprising at least one helically-shaped tube 11, and an expansion valve 130 operatively coupled to a control sensor 140 and / or temperature sensor 140 and / or pressure sensor 140.

[0052] In the evaporator 120 as shown in fig. 1, refrigerant 1 absorbs heat from a heat source (water and / or air or the like), causing refrigerant 1 to evaporate and turn into a gas at low pressure. In the compressor 110, this refrigerant gas 1 is then compressed through the compressor 110, which increases the pressure and temperature of the refrigerant gas 1. Then, the condenser 10 receives the refrigerant gas 1 via an inlet pipe connector 16 of the heat pump system 100 flowing into a tube 11 of the condenser 10 via an inlet 12 of the condenser 10 (the condenser tube 11 is wrapped / winded as a separate item and in physical contact with the outside and shell of the container 3 for water 2 to be heated, see fig. 2), whereby the hot, high-pressure refrigerant gas 1 enters the condenser 10. In the condenser 10, the refrigerant gas 1 flows through the condenser tube 11 first releasing excess heat (so called de-superheating) to the condenser tube 11 and further to the outside or shell of the container 3 and to the water 2 inside the container (usually, non-heated water 2 enters the bottom of the container 3 but could in some aspects enter the container at another position or level depending on application and need). As the refrigerant gas 1 continues to flow through the tube 11 and cool in the condenser 10 while flowing around the container 3 following the winding / coiling of the condenser tube 11 due to heat exchange with primarily the container 3 and the water 2, the refrigerant gas 1 transitions from gas to liquid through condensation. During this process, refrigerant 1 is in both gas and liquid forms (two-phase region). Finally, the refrigerant 1 becomes a fully saturated liquid and cools further below the condensation point (subcooling) while flowing through the condenser tube 11 and is finally let out as a colder liquid at an outlet 13 of the condenser 10 being the end of the condenser tube 11 in fluid connection with an outlet pipe connector 17 of the heat pump system 100 and the refrigerant 1 flows into the heat pump cycle again. The density of the refrigerant 1 increases significantly when transitioning from a gas to a liquid in the condenser 10. The liquid refrigerant 1 then enters the expansion valve 130 and the liquid refrigerant 1 passes through this valve 130 dropping in pressure and cooling down before returning to the evaporator 120. The expansion valve 130 regulates the flow of refrigerant according to the temperature measured by the temperature sensor 140 and assures that at the outlet of the evaporator 120, the refrigerant is in superheated vapour state, without liquid droplets. This cycle repeats, moving heat from one place to another, effectively heating the water 2 in the container

[0053] In fig. 2, a tubular condenser 10 according to the disclosure comprises a tube 11 configured to be helically arranged around and in contact with the container 3 by means of an inner surface 14 by being winded or coiled around the outside and shell of the container during manufacture. The contact between the inner surface 14 of the tubular condenser 10 and the outer shell of the container 3, i.e., the tube 11 making up the condenser 10 is in some aspects enhanced by use of a contact enhancing and thermal improving paste applied between the inner surface 14 of the tubular condenser 10 and the outside of the shell of the container 3.

[0054] According to the disclosure, the condenser 10 is configured to be used in any heat pump system 100 for exchanging heat between a refrigerant 1 inside the tube 11 of the condenser 10 and the water 2 in the container 3, commonly during operation of the heat pump system 100. However, in some aspects, heat exchange still occurs during a short still stand or non-operation of the heat pump system 100.

[0055] The condenser 10 and its tube 11 enable throughput of refrigerant 1 coming from the heat pump system 100 via the first tube end 12 shown extending vertically in figs. 2 to 4D but could in some aspects extend horizontally or inclined. The first tube end 12 of the condenser 10 is a refrigerant inlet of the condenser 10. The condenser tube 11 enables throughput and outlet of the refrigerant 1 via the second tube end 13 acting as a refrigerant outlet of the condenser 10 for return into the other parts of the heat pump system 100 and to be used anew in the heat pump cycle if not turned off to not be operating. The second tube end 13 extends vertically in figs. 2 to 4D but could in some aspects extend horizontally or inclined.

[0056] In fig. 2, the tubular condenser 10 is shown after being wrapped or winded or coiled as a spiral or helix around and in contact with the inner surface 14 to the outer shell of the metal container 3 and with an outer surface 15 facing outwards forming the outside of the helically or spirally shaped tubular condenser 10 (see also figs. 3A, 3B, 5A to 5I clearly showing this inner surface 14 arranged to the left, even though fig. 5E could show the opposite as not being in perspective). In fig. 5E, the reference numerals 14 and 15 could actually change place as is clearly understood by a skilled person as inner and outer surfaces 14 and 15 have the same shape and size and / or area and / or height while in figs. 5F, 5G, 5H and 5I, the left inner surface 14 is the one to be in contact with the outer shell of the container 3 to achieve the best heat exchange effect by better contact over a larger area and therefore providing improved conduction, i.e., heat conduction, therewith. The outer surface 15 of the tubular condenser 10 is formed by being flattened similar or in the same way as the inner surface 14 and / or indented radially inwards into a partly inwards bent surface and / or partly flat surface to reduce the radial extension TW of the tube 11 of the condenser to enable the container 3 and the condenser 10 to occupy less total space radially together and give more room or space for insulation around these entities 3 and 10, the insulation is not shown.

[0057] The tube 11 making up the condenser 10 has a length TL (see figs. 2, 3A to 4D, 6 and 7, however, all tubes 11 of the disclosure have of course a length). The length TL of the tube 11 could be the whole tube length or the length between the ends 12 and 13 depending on how long, i.e., the length LE 1 , LE 2 for each of the ends 12 and 13 is, but - according to the disclosure - the length TL of the tube 11 is referred to as the tube length starting where the extension of the first tube end 12 ends - in the flow direction of refrigerant 1- and where the extension of the second or last tube end 13 starts in the flow direction of refrigerant 1. This is due to that the tube ends 12 and 13 and their lengths LE 1 , LE 2 are preferably not formed or shaped with a varying cross-section as the remaining length TL of the tube 11 according to the invention but could be.

[0058] The length TL of the tube 11 at least partly comprises a varying cross-sectional shape A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" along one or more length sections preferably at least two length sections with shape(s) A, A', A" and / or B, B', B" and / or C, C', C", D, D', D" and / or E, E', E", F, F', F" being differing and varying cross-sectional shapes (see figs. 2 to 5I) between the two tube ends 12, 13. Hence, in the disclosure, when referring to any length section(s) denoted with any of the letters A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" this means that the concerned tube length section(s) has / have been formed into one or more of these concerned cross-sectional shapes before being wrapped around the container 3.

[0059] The tube 11 making up the condenser 10 has or is shaped into a helical and / or spiral shape with an inner size and / or inner shape and / or inner surface and / or inner circumference and / or diameter SD i and an outer size and / or outer shape and / or outer circumference / diameter SD o (see figs. 4A to 4C, 5A, 5B, 5D, 5I and 6) being adapted to the outside and / or outer size and / or outer mantle and / or shell surface and / or outer shape and / or outer circumference and / or outer diameter CD o of the container 3 for water 2 by being winded or coiled around the container 3 by use of a device 90, 90'. (see figs. 2 and 7). In some aspects, the condenser 10 comprises a tube 11 made up of at least two length sections of similar or same or equal or different lengths or each of the two length sections has a length being half the tube length TL.

[0060] The device 90, 90' is a tube forming machine with at least two rolls 91, i.e., at least one or more pairs of counterrotating rolls as seen in fig. 7. The tube forming machine 90 is shown schematically as a box in solid lines together with the rolls 91 in fig. 7 at and in operative connection with the first end 12 of the tube 11. In some aspects, a corresponding tube forming machine 90' is shown in dashed lines in fig, 7 at and in operative connection with the second end 13 of the tube 11. This visualizes that either the first tube end 12 or the second tube end 3 can be the first tube end introduced into the tube forming machine 90, 90' and be the first tube end ejected from the tube forming machine to be formed around the container 3. If the second tube end 13 is first introduced into the tube forming machine 90' then the shown arrows in dashed lines visualize the direction of feeding the second tube end 13 while the arrows in solid lines show the feeding direction of the first tube end 12 when being firstly introduced into the tube forming machine 90.

[0061] The rolls 91 are configured to rotate in contact with the tube 11 while forming the cross-sectional shape(s) of one or two or more length sections of the tube into any of the shown varying shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" or forming the cross-sectional shape(s) of one or two or more length sections with any combination of two or more of those cross-sectional shapes of figs. 5A to 5I or 9. The tube forming machine 90, 90' - in some aspects - only forms the length TL of the tube 11 between the lengths LE 1 and LE 2 of the first and the second tube ends 12, 13 being shown in figs. 4A to 4D, as explained above. The lengths LE 1 , LE 2 for each of the tube ends 12 and 13 could be of any length.

[0062] During the forming of the condenser tube 11 while being fed in the directions of the white arrows (shown in solid or dashed lines) in fig. 7, the tube is also winded or coiled around the container 3 into different coil and / or thread patterns and / or pitches of the spirally and / or helically wound and / or helix-shaped tubular condenser 10 along the outer surface and shell of the container and along a vertical center axis CCA of the container and its own vertical center axis SCA as seen in figs. 2, 4A to 4D, and 7. In fig. 7, the top windings or coils at the denotation A, A', A" of the condenser 10 are winded with a pitch being larger than both the intermediate windings or coils at the denotations B, B', B", C, C', C" and the bottom windings or coils at the denotations D, D', D" (and / or compared to the windings E (E', E"), F (F', F") of fig. 5H) - similar to the pitches and winding / coil pattern in figs. 2, 3A and 4A, but these pitches could be made with other and different pitches as shown in figs. 4B and 4D or have the same pitch as shown in figs. 3B and 4C. Hence, also the cross-sectional shapes referred to as A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" (and G, H and I in fig. 9 that also could be shapes G', G" and / or H', H" and / or I', I") in figs. 5A to 5I are possible to combine or apply at different levels or for different winding or coil patterns and / or for different or the same pitches as long as the total inner volume decreases and the total tube height TH increases from the top windings or coils with shape(s) O / A as seen in figs. 2 to 5I, and 7 to and through the bottom windings or coils with shape(s) C, C', B", D, D', E and / or F towards the second tube end 13 with a last shape B, B', B" (if two length sections with different shapes form the condenser tube 11); C, C', C" (if three length sections with different shapes form the condenser tube 11); D, D', D" (if four length sections with different shapes form the condenser tube); E, E', E" (if five length sections with different shapes form the condenser tube) and F, F', F" (if six length sections with different shapes form the condenser tube) transferred into shape O along the bottom bend TRA. In some aspects, the tube length section between the bottom shape transition area or bend TRA with tube shape O and the length LE 2 of the outlet tube end 13 has an increased height TH and shape, such as shape D in figs. 4A, 5A, 5B and 5C; shape D' in fig. 4B; shape C" in fig. 4C, and shape F in figs. 4D and optionally in figs. 5H and 5I to further increase contact surface and heat transfer. In some aspects, the lengths LE 1 and LE 2 for the tube ends 12 and 13 with shape O are minimized to further increase or optimize the length of the tube 11 having the varying shapes A to F" (and / or shapes G to I") to further improve the performance of the condenser 10.

[0063] In some aspects, the at least two rolls 91 of the tube forming machine 90 of fig. 7 may also actively push or feed the tube 11 through and out of the tube forming machine 90 instead of only passively rotating while the tube is pulled through the tube forming machine 90, 90'. In some aspects, the tube end 12 or 13 to be firstly introduced into and fed out of the tube forming machine 90 or 90', respectively, to enable forming the tube 11 around the container 3 is attached by clamping or the like to the container 3, which container then is rotated pulling the tube 11 out of the tube forming machine while bending the tube around its circumference and outer shell until the helically shaped condenser 10 is wrapped around the container with the inner surface 14 in contact with the outer shell of the container 3 (the different rotational directions of the container 3 when being rotated pulling the tube 11 is shown with the lower curved arrows in solid and dashed lines). In some aspects, the container 3 is not filled with water 2 when the tubular condenser 10 is formed around it.

[0064] The tube forming machine 90, 90' uses an adjustability of the distance RD between the rolls 91, such as the distance between the rotary axes of the rolls, to form the cross-sectional shape of the tube 11 from a circular one at and along its ends 12 and 13 to one or more of the varying cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" shown in figs. 5A to 5I along at least two length sections. This forming is primarily increasing the height TH of the tube 11 (both the inner and outer tube height) while decreasing the thickness or width TW of the tube 11 (both the inner and outer tube width) as shown in all views in figs. 3A to 5G and in 5I, and 6, even though these dimensional parameters are not denoted in each view as these dimensional features of course are parts of the actual physical tube 11.

[0065] However, in some aspects, such as in fig. 5H, the first or top cross-sectional shape A or A' or A" provides a smaller inner volume along the first or top length section than the inner volume provided by the next or second length section having the second cross-sectional shape, B or B' or B", e.g., the first or top cross-sectional shape A or A' or A" could have a similar or the same inner volume as the third cross-sectional shape C, C', C" or as the fourth cross-sectional shape D, D', D" or as fifth cross-sectional shape E, E', E" or as the sixth cross-sectional shape, F, F', F" or any other cross-sectional shape of higher order as long as the total inner volume along the tube decreases from the first and top cross-sectional shape to the last or bottom cross-sectional shape.

[0066] In some aspects, see figs. 4D and 5I, the first or top section has two tube windings with a cross-sectional shape A or A' or A" providing a larger inner volume along the first or top length section than the inner volume provided by the next or second section with two length sections having the second cross-sectional shape B or B' or B", which second section having two length sections with shape B or B' or B" has a larger inner volume than the next or third section with two length sections having the cross-sectional shape C, C', C", and this third section with two length sections with shape C, C', C" has a larger inner volume than the next or the fourth section with two length sections having the cross-sectional shape D, D', D", which fourth section with the two length sections having the cross-sectional shape D, D', D" has a larger inner volume than the next or the fifth section with three length sections having the cross-sectional shape E, E', E", and the fifth section having three length sections with the cross-sectional shape E, E', E" has a larger inner volume than the next or the sixth section with two tube length sections having the cross-sectional shape, F, F', F" providing a decrease of the total inner volume along the tube 11 from the first and top section to the last and bottom section in the direction of flow of refrigerant 1. In some aspects, the condenser 10 could have a fourth section with two length sections having the cross-sectional shape D, D', D" and a larger inner volume than the next or the fifth section with two instead of three length sections having the cross-sectional shape E, E', E". In some aspects, the condenser 10 could have each section with one or three or more length sections or a combination of different number of length sections having the corresponding cross-sectional shape A to F" as long as the inner volume decreases in accordance with or following the change of state of the refrigerant 1 when flowing from the first tube end 12 to the second tube end 13, i.e., the outlet of the condenser tube 11.

[0067] This forming by means of the tube forming machine 90, 90' and its rolls 91 incurs a length or section or part of transition TRA between the circular and tubular cross-sections with shape O as shown in figure 8 along the lengths LE 1 and LE 2 of the two tube ends 12 and 13 and forms the remaining length TL of the tube 11 with one or more of the length sections being formed with one or more varying and non-circular cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" (each TRA at straight lengths and at / along bends are encircled by dashed circles in figs. 2 to 4D, 5H, 5I, 6, and 7. However, in some aspects these transition areas TRA do not necessarily have to be located at any tube bends, one or more or all of these transition areas TRA could be arranged at straight tube parts if the inlet end 12 and / or outlet end 13 extended in a straight or more or less inclined fashion or if any bended or curved transition area TRA has a circular cross-section O being preferred when bending the tube 11 and / or if any straight transition area TRA is located between any of the lengths LE 1 and / or LE 2 of the first end 12 and / or the second end 13 as shown as an example in figs. 3C to 4D, 5H and 5I. Furthermore, in some aspects, the transition length(s) / section(s) TRA between the circular cross-sectional shapes O of the first and second tube ends 12, 13 and any last or second length section or third length section or fourth length section with other shape(s) could also be in some aspects as transition between the circular cross-sectional shapes of the first and second tube ends 12, 13 and any fifth or sixth or higher order length section with other shape(s). In other words, any length of the tube 11 between the first or last winding or coil of the condenser 10 and where the first end 12 ends and the second end 13 begins and / or where any transition area TRA (as shown in figs. 5H and 5I) begin(s) or end(s) may also be provided with one or more varying cross-sectional shapes as long as the total inner volume along the tube 11 from the first and top section to the last and bottom section in the direction of flow of refrigerant 1 is decreased. Any of the shown cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" and any combination of those cross-sectional shapes are achieved by pressing or actually squeezing the outside of the tube 11 by means of the rolls 91 more or less and - in some aspects - using rolls with planar surfaces and / or with different profiles or shapes between which the tube is pressed to form the tube.

[0068] According to the disclosure, the inventive condenser 10, i.e., its helically shaped tube 11, and the inner shape and / or inner circumference and / or inner surface of each tube winding and / or inner diameter SD i of the tube 11 comprises the inner surface 14 being flattened by the tube forming machine 90, 90' and its rolls 91 squeezing the tube 11 into a flat surface 14 extending along the tube length TL and along the tube height TH of the helically shaped tube 11 (see figs. 5A to 5I). The inner flat surface 14 faces radially inwards to be at least partly or substantially or fully in contact with the outer shell or mantle surface and / or outer circumference and outer diameter CD o of the container 3 when the condenser tube 11 is being or has been coiled around the outer shell of the container 3 as shown in figs. 1 and 2.

[0069] According to the disclosure, the helically shaped tube 11 also has an outer size and / or shape and / or surface and / or area with an outer circumference and / or outer diameter SD o (see figs. 4A, 4B, 4C, 5A, 5B, 5D and 6). In some aspects, the outer surface and / or area and outer circumference and / or diameter SD o of the tube 11 comprises an outer at least partly indented surface 15 (see figs. 5D (bottom view), and 5G) at or extending at least partly of fully along the tube length TL and tube height TH of the helically shaped tube 11 and along one or more length sections A", B", C", D", E", F") (see figs. 4C, 5D (bottom view), 5G, 5H, 5I and 6). In some aspects, the outer surface and / or area and outer circumference and / or outer diameter SD o of the tube 11 comprises one or more at least partly flat surfaces 15 extending at least partly of fully along the tube length TL and tube height TH of the helically shaped tube 11 and along one or more length sections A', A", B, B' (see figs. 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5I and 6). According to the disclosure, the outer partly indented and / or partly flat surface 15 of the tube 11 is configured to face radially outwards from the outer shell surface CD o of the container 3 when the tube is being wrapped or winded or has been winded around the container 3 by the forming machine 90 and its rolls 91. The helically shaped tube 11 has a tube width TW as shown in figs. 5B, 5C, 5D, 5H, 5I and 7, however all tubes according to the disclosure have of course a width and / or a diameter depending on its shape. The flat or flattened inner contact surface or area 14 of the tube 11 has a size with a length and / or height FI i , which is part of all embodiments of the tube 11, but only denoted in the two upper views in fig. 5B, and in all views of figs. 5C to 5H, even though figs. 5E to 5G only denotes this dimension of the inner flat contact surface 14 by arrows and straight lines to mark the position thereof, the same goes for fig. 5I as tube 11 is a physical entity. The - in some aspects - at least partly flat or flattened outer contact surface or area 15 of the tube 11 also has a size with a length and / or height FI o , which is part of at least one or some or all embodiments of the tube 11, but only denoted in the two upper views in fig. 5B, and in all views of figs. 5C, 5E, 5F and 5H, and in the two upper views of fig. 5D, even though figs. 5E to 5G only denotes this dimension of the outer surface 15 by arrows and straight lines to mark the position thereof, the same goes for fig. 5I as tube 11 is a physical entity. Preferably, the condenser tube 11 is made with both the inner surface 14 and the outer surface 15 at least partly flat or with an as great extension or area as possible to maximize the contact surface 14 against the shell of the container 3 and minimize the radial occupancy of space to make the tube as thin as possible while still enabling a sufficient function and flow of refrigerant 1 and as high heat exchange as possible and thereby maximizing the ability to apply more or thicker insulation around both the container 3 and the condenser 10 after manufacture. The pattern of the coiled condenser 10 in fig. 5H corresponds to the ones of figs. 3A and 4A, hence, these aspects are combinable and inherit each other's applicability, such as providing the condenser 10 of fig. 3A and / or fig. 4A with one or more any other combination of the cross-sectional shapes E and F or vice versa, as another example, by providing the condenser 10 of fig. 4C with one or more any other combination of for example the cross-sectional shapes E" and F" of fig. 5G and / or the cross-sectional shapes E and F in fig. 5I and 4D instead of the shown ones in fig. 4C and / or as complementary shapes therein or vice versa, the same combinability is applicable for all the shown condensers 10 as the tube 11 can be shaped in any combination of shapes A to I" and along different numbers of windings / coils and lengths along the tube as long as its inner volume decreases while its height TH increases as intended by applying the invention in the direction of refrigerant flow.

[0070] The condenser tube 11 has a length and / or height HL - as measured in the vertical direction of the center axis SCA for the condenser 10 - between where the transition areas or parts TRA of each of the lengths LE 1 , LE 2 and circular cross-sections O of the first and the second tube ends 12 and 13 start or end, respectively, and where the longitudinal length TL of the tube with the at least two length sections start or end, respectively, with different and varying and non-circular cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" when finally made and winded or coiled around the container 3 into the finished condenser 10 having a spiral or helical shape or helix with height HL as shown in figs. 2, 3A, 3B, 4A to 4D, 5H, 5I and 7. This total height HL is adaptable to different heights and depend also on how dense the pitch is for the condenser 10 as longer distance between the windings or threads or coils of the tube 11 means higher height while smaller distance means lower height HL. This height HL also depends on the actual length TL of the tube 11 and the additional lengths LE 1 and LE 2 of its ends 12 and 13 and the cross-sectional shapes A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" along the length TL and the thickness of the tube walls and the thereby resulting inner volume of the tube 11 to actually provide a desired function and heat exchange when using a specific charge of refrigerant 1 in the heat pump system 100, in particular, achieving the optimized use of the small charge of propane being between 130 to 160 grams, preferably about 135 to 155 grams or more preferred about 140 to 154 grams or between 148 to 153 grams or most preferred about 152 or exactly 152 grams. In some applications, and depending on operational conditions in the heat pump system 100, such as flow rate and heat output and demand etc., the refrigerant charge or amount of propane in the condenser 10 may be between 20 grams to 100 grams.

[0071] In some aspects, the inner flat surface 14 of the helically shaped tube 11 of the condenser 10 is configured to extend along or cover or form part of an area of the height TH of the helically shaped tube 11 being of similar or same size or same area or being of different size or different area or larger size or larger area compared to the one of the outer flat surface 15. This is shown as the cross-sectional shapes A, B, C and D in fig. 5A; in the two lower or bottom views of cross-sectional shapes C and D in fig. 5B (even though these parameters are not drafted in those views, these shapes C and D correspond to the same ones in figs. 5A and 5C, the same goes for shape A in the middle view of fig. 5D as this shape corresponds to the same A-shapes in figs. 5A and 5C), and in figs. 5E, 5H and 5I where the heights or lengths FI i and FI o of the inner flat surface 14 and the outer flat surface 15, respectively, are of similar heights or lengths or about the same heights or lengths or the same heights or lengths and therefore substantially having about the same or the same areas. In figs. 5B (the two upper views showing the cross-sectional shapes A' and B'); 5D (top view showing a similar or the same cross-sectional shape A' as in the top view of fig. 5B), and in fig. 5F, the heights or lengths FI i and FI o of the inner flat surface 14 and the outer flat surface 15, respectively, are different, i.e., the height or length FI o of the outer flat surface 15 is less or smaller than the height or length FI i of the inner flat surface 14, whereby the inner flat contact surface 14 is larger than the outer flat surface 15. In fig. 5D (bottom view showing a differently shaped cross-section A" with an indent in the outer surface 15 making it non-flat) and in fig. 5G showing a similar shape or shapes A", B", C", D" with an indented outer surface 15, the height or length FI o of the outer flat surface 15 could be less or smaller or larger or the same as the height or length FI i of the inner flat surface 14. In some aspects, the one or preferably two or more at least partly varying and at least partly non-circular cross-sectional shapes of any length section A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" making up the length TL of the tube 11 has / have at least partly or fully a flat sided oval shape or at least partly or fully a flat sided elliptic shape or at least partly or fully a rounded rectangle shape or at least partly or fully a stadium shape as seen in figs. 5A to 5I.

[0072] According to the disclosure, the condenser 10 comprises a lengthwise at least partly varying cross-sectional shape of the tube 11, which at least partly varying cross-sectional tube shape A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" is configured to vary from where the first tube end 12 ends and the second tube end 13 starts in figs. 2, 3A, 3B, 4A, 4B, 4C, 5H, 5I and 7, such that the cross-sectional inner area and thereby the inner volume of the tube 11 is the smallest towards or at or closer to or closest to or adjacent the second tube end 13. In some aspects, this decrease of the inner volume of the tube 11 is linear while in some aspects non-linear and occurs in some aspects in smaller or larger steps in view of change of cross-sectional shape(s) A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" or in very small steps or in principle infinitely variable and very smooth transition along the length TL of the tube 11.

[0073] The helical shape of the tube 11 of the condenser 10 is in some aspects a helix with constant pitch (see figs. 3B and 4C). In some other aspects, the helical shape of the condenser tube 11 is a helix with varying pitch (see figs. 2, 3A, 4A, 4B, 4D, 5H and 5I). In some aspects, the helically shaped condenser tube 11 is a helix with any combination of any constant pitch and / or any varying pitch (not shown). In some aspects, the helical shape of the tube 11 of the condenser 10 is a helix with the distance between each turn or pitch being constant along a part or along the whole length or height HL and the axis SCA of the helix as seen in figs. 3B and 4C. In some aspects, the helical-shaped condenser tube 11 is a variable-pitch helix with a pitch varying or changing along at least a part of the length or height HL and axis SCA of the helix as shown in figs. 4A, 4B and 4D. In some aspects, the helical-shaped condenser tube 11 is a variable-pitch helix with a pitch varying or changing along the whole length or height HL and axis SCA of the helix as shown in figs. 4B and 4D. In some aspects, the helical-shaped condenser tube 11 is a variable-pitch helix having a first pitch varying or changing along at least a part of the length or height HL and axis SCA of the helix and a second pitch being constant along at least another part of the length or height HL and axis SCA of the helix. The helical shape of the condenser tube 11 is in some aspects a helix with the distance between the turns or pitch being larger along at least a first length section A, C, E of the helix along height HL and axis SCA of the helix and smaller along at least another or second or third or fourth or more length sections B, D, F of the helix along the height HL and axis SCA of the helix as seen in figs. 3A, 4A, 4B, 4D, 5H and 5I.

[0074] The condenser tube 11 making up the condenser 10 shown in figs. 3A and 4A is a helix with the distance between the turns or the pitch decreasing along a first length section A of the helix tube and along the height HL and center axis SCA to a second length section B of the helix tube along which second length section B or after this second length section B ends the pitch increases towards or to a third or fourth length section C, D of the helix tube along which third or fourth length section of the helix tube the pitch decreases again along the axis SCA. All of the described helixes of the condenser tube 11 making up the condenser 10 according to the disclosure could be combined, e.g., having a constant pitch in an intermediate length section B, B', B", C, C', C" while one or more other length sections have varying pitches and a first length section A, A', A" and / or a last length section D, D', D" has / have constant pitches. However, it is more preferred to have a denser pitch closer or at the bottom of the container 3 at the last length section(s) D, D', D", F, F', F", such as in figs. 5H and 5I, to provide an improved heat exchange where colder water 2 enters the container.

[0075] According to the disclosure, a method of manufacturing the condenser 10 for use in the heat pump system 100 is achieved by means of the tube forming machine 90 with the counter-rotating rolls 91 as shown in fig. 7. Firstly, the first or second tube end 12, 13 is introduced into the tube forming machine 90 and between the rolls 91. The feeding of the tube 11 starts at one of its ends 12 or 13 and the tube is fed through the machine 90 with the full-length TL before the other tube end is introduced therein and fed through. Then, the first tube end 12, 13 and the length TL of the tube 11 is fed through the tube forming machine 90 while forming the tube at least partly along at least a first length section A, A', A", B, B', B" and a second length section C, C', C", D, D', D" of the tube length TL into a varying cross-sectional shape and inner volume of the tube along its length TL and forming the tube length TL with at least one but preferably two flat and opposite surfaces 14, 15 along at least a part of one or preferably two or more or each tube length section A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F". In some embodiments, the tube length TL is formed with one flat inner surface 14 and one non-flat or at least partly indented outer surface 15 as opposite surfaces along at least a part of one or two or more tube length sections A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F". Then, the tube 11 is ejected or fed out from the forming machine 90, and winded or coiled with each tube length section A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" into a helically shaped tube 11 around the container 3 with at least one flat inner surface 14 facing radially inwards forming an inner flat contact surface 14 at least partly or substantially or fully in contact with a first area of the outer shell and / or outer circumference and / or envelope surface CD o of the container 3.

[0076] According to the disclosure, the method of manufacturing the condenser 10 comprises forming the tube 11 - by the tube forming machine 90, 90' and its rolls 91 - at least partly along at least one of the tube length sections of the tube length TL after the length LE 1 of the first tube end 12 has firstly been fed past the rolls 91 in the tube forming machine 90 or the length LE 2 of the second tube end 13 has firstly been fed past the rolls 91 in the tube forming machine 90' (see fig. 7) into one varying cross-sectional shape A, A', A" with one varying inner volume, and forming the tube 11 at least partly along at least another tube length section of the tube length TL into another varying cross-sectional shape B, B', B", C, C', C", D, D', D" with another varying inner volume being smaller than the varying inner volume of the other and first and former tube length section A, A', A" to provide the decreasing total inner volume along the tube 11 from the first and top section to the last and bottom section for the refrigerant 1 to flow through.

[0077] In some aspects, the method of manufacturing the condenser 10 further comprises winding or coiling each of the length sections A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F" along the tube length TL of the tube 11 into the helically shaped tubular condenser 10 around the container 3 with the inner flat contact surface 14 always facing radially inwards and being at least partly or substantially or fully in contact with an area of the outer shell CDo of the container 3 being different from any area of the shell of the container that any other tube length section is winded or coiled around.

[0078] In some aspects, the method of manufacturing the condenser 10 also comprises forming, by means of the tube forming machine 90, 90', at least a first tube length section of the tube length TL of the tube 11 into a first varying cross-sectional shape A, A', A", B, B', B", C, C', C", D, D', D" with a first varying inner volume along the first half of the length TL of the tube 11 and forming at least a second tube length section into a second varying cross-sectional shape C, C', C", D, D', D", E, E', E", F, F', F", G (G', G" not shown), H (H', H" not shown), I (I',I" not shown) with a second or last varying inner volume along the second half of the tube length TL of the tube 11, which second or last varying inner volume is smaller than the first varying inner volume of the first tube length section(s) A, A', A", B, B', B" and / or any intermediate sections C, C', C", D, D', D".

[0079] In some aspects, the method of manufacturing the condenser 10 further comprises feeding a first tube end 12, 13 into and past the rolls 91 through the tube forming machine 90, 90' and ejecting the first tube end from the forming machine without changing the form of the first tube end, and feeding the second tube end 12, 13 into and past the rolls 91 through the tube forming machine 90, 90' and ejecting the second tube end from the forming machine without changing the form of the second tube end.

[0080] In some aspects, the method of manufacturing the condenser 10 comprises forming, by means of the tube forming machine 90, 90', the length TL of the tube 11 between the end of the length LE 1 of the first tube end 12 and the start of the length LE 2 of the second tube end 13 with at least one or preferably at least two partly varying cross-sectional shapes C, C', C", D, D', D", E, E', E", F, F', F" and at least one or preferably at least two partly varying inner volumes and with at least two flat and opposite surfaces 14, 15 along at least a part of the tube length TL, such that the at least partly varying inner volume(s) decrease(s) after the length LE 1 of the first tube end 12 ends towards and until the length LE 2 of the second tube end 13 starts.

[0081] The graph or plot in fig. 9 illustrates the refrigerant charge distribution (on the y-axis) in the condenser 10 along the condenser tube length TL and along the varying cross-sectional shapes A, B, C, D, E, F, G, H and I (on the x-axis). The x-axis represents the position along the condenser tube 11 (from shape A (applicable to shapes A', A") with lowest height TH (and widest width TW) to shapes B, C, D, E, F, H and / or I (applicable to shapes B', B", C', C", D', D", E', E", F', F" (or shapes H', H" and / or I', I" not shown)) with increasing and / or greatest heights TH (and decreasing and / or smallest width(s) TW)), with the refrigerant entering at x = 0 in length (via inlet 12 having tube shape O (circular cross-sectional shape of the condenser tube 11)) and exiting at / through shape F or G or H or I etc. (with smallest width(s) TW) via the outlet 13. Vertical dotted lines indicate the locations where internal volume is reduced, i.e., where the tube 11 changes cross-sectional shape from O to A (along / after length LE 1 of inlet 12 and / or before / in / after TRA / bends) or A to B or B to C or C to D or D to E or E to F or F to G or G to H or H to I (or I to J - (shape J, J' or J" is not shown)) and lastly from C / D / E / F / G to O again and vice versa (before / in / after TRA / bends and / or before / along length LE 2 of outlet 13 seen as squeezing points or shape transition areas or length sections of the tube 11). The graph of fig. 9 clearly shows that, without these flattened or squeezed tube length sections of the condenser 10 in the direction of the width TW, the refrigerant charge would increase exponentially as in prior art condensers. In contrast to prior art solutions, this optimized condenser design according to the disclosure - and as achieved with all of the designs of the condenser 10 shown exemplified in figs. 2 to 4D, 5H, 5I and 7 - flattens the refrigerant charge curve, demonstrating a more controlled and efficient refrigerant charge distribution to enable good and improved performance of the heat exchange system even though the refrigerant charge is below 150 to 155 grams or about 151 to 153 grams compared to prior art ones.

[0082] In fig. 5I (view A - A), the last shapes E and F actually have an inner width TW providing an inner volume smaller than the upper or upstream shapes even though fig. 5I is not showing this as clearly as the upper shapes A to D do. The last or lowest shapes E and F in fig. 5I are actually similar or the same or at least equivalent to the last or lowest shapes E and F in fig. 5H clearly showing the existence of an inner volume in higher or greater magnification.NOMENCLATURE

[0083] 1: Refrigerant in the form of propane. 2: Water in fluid / viscous / liquid and / or gas / vapor form. 3: Container of metal for containing water 2. 4: Inlet of (non-heated / cold) water into the container 3. 5: Outlet of (hot / hotter / warm / warmer) water out of the container 3. 10: Heat exchanger / Heat exchanging device or condenser. 11: Helically wound tube of condenser 10 12: First tube end of condenser 10. 13: Second tube end of condenser 10. 14: Inner flat surface of the tube 11. 15: Outer flat surface of the tube 11. 16: Pipe connection between inlet 12 and the heat pump system 100. 17: Pipe connection between outlet 13 and the heat pump system 100. 90, 90': Tube forming machine with rolls. 91: Tube forming rolls of the tube forming machine 90, 90'. 100: Heat pump system. 110: Compressor. 120: Evaporator. 130: Thermal expansion valve 140: Evaporator outlet temperature measurement for superheat control. C, C', C", D, D', D", E, E', E", F, F', F", G, G', G", H, H', H", I, I', I": Different cross-section(s) of the tube 11 along a part or section or parts or sections of its length TL or along its full length TL and / or along two or more length sections of the tube 11. SCA: Center axis of the helical-shaped tube 11. CCA: Center axis of the container 3. FL i : Size / Length / Height of the flat / flattened inner contact surface / area 14 of tube 11. FL o : Size / Length / Height of the flat / flattened outer surface / area 15 of tube 11. HL: Length / Height of the helical shape / helix part of the tube 11. LE 1 : Length of the first tube end 12. LE 2 : Length of the second tube end 13. RD: Adjustable distance between rolls 91 of the tube forming machine 90. SD i : Inner size and / or shape and / or diameter of the condenser tube 11. SD O : Outer size and / or shape and / or diameter of the condenser tube 11. CD o : Outer size and / or shape and / or diameter of the water container 3. TRA: Transition length(s) / section(s) / bend(s) with shape O between changing cross-sectional shapes. TL: Length of the tube 11. TH: Vertical height of the tube 11. TW: Horizontal width or thickness of the tube 11.

Examples

Embodiment Construction

[0049]The present disclosure will now be described with reference to the accompanying drawings 1 to 9, in which preferred example aspects of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed aspects. The disclosed aspects are provided to fully convey the scope of the disclosure to the skilled person. All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

[0050]In particular, figures 5A, 5C, 5H and 5I show - in perspective - enlarged cross-sectional parts or sections and / or shapes of the invention, a tubular condenser 10, in cutout views (to the right in figs. 5H and 5I) corresponding to the cutout views in figs. 4A, 4D and 5A for enhanced overview of dimensions of these entities not shown by arrows and denotations in figs. 4A, 4D and 5A (such as ...

Claims

1. A condenser (10) for use in a heat pump system (100) for exchanging heat between a refrigerant (1) and water (2) in a container (3), the condenser (10) comprising a tube (11) through which the refrigerant (1) is configured to flow via a first tube end (12) being a refrigerant inlet of the condenser (10) and a second tube end (13) being a refrigerant outlet of the condenser, wherein the tube (11) of the condenser (10) has a length (TL) and a height (TH) in the vertical direction, which length (TL) at least partly comprises a varying cross-sectional shape along one or more length sections having at least one or more different and / or one or more similar and / or one or more of the same varying cross-sectional shapes (A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F", G, G', G", H, H', H", I, I', I") between the two tube ends (12, 13), and the tube (11) is configured with a helical shape having an inner size and / or inner shape and / or inner circumference and / or inner diameter (SDi) being adapted to the outer surface and / or shell and / or outer shape and / or outer circumference and / or outer diameter (CDo) of the container (3), wherein the inner shape and / or inner circumference and / or inner diameter (SDi) of the helically shaped tube (11) of the condenser (10) comprises an inner flat surface (14) along the length (TL) and height (TH) of the helically shaped tube (11), the inner flat surface (14) being configured to face radially towards and be substantially or fully in contact with the outer shell surface (CDo) of the container (3), characterized in that the height (TH) of the helically shaped tube (11) is increasing along at least two length sections in the direction of flow of the refrigerant (1) from the first tube end (12) to the second tube end (13).

2. The condenser (10) according to any preceding claim, wherein the height (TH) of the helically shaped tube (11) is increasing along at least two, three or more length sections from lower to greater heights (TH) in the direction of flow of the refrigerant (1) from the first tube end (12) to the second tube end (13).

3. The condenser (10) according to any preceding claim, wherein the inner flat surface (14) and / or the outer surface (15) of the helically shaped tube (11) is / are configured to extend along a substantial part of the height (TH) of the helically shaped tube or is / are configured to extend along a substantial part of the full height (TH) of the helically shaped tube or is / are configured to extend along almost or nearly the whole full height (TH) of the helically shaped tube.

4. The condenser (10) according to any preceding claim, wherein the tube (11) of the condenser (10) comprises at least two length sections having at least one partly varying cross-sectional shape (A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F") with partly varying inner volume differing from each other's cross-sectional shapes and inner volumes and / or differing from any cross-sectional shape and inner volume of one or more of the other length sections of the tube in the direction of flow of the refrigerant (1) from the first tube end (12) to the second tube end (13).

5. The condenser (10) according to any preceding claim, wherein the inner flat surface (14) and the outer surface (15) of the helically shaped tube (11) are arranged opposite each other and are flattened to different extents or to similar extent or the same extent along the height (TH) of the helically shaped tube (11).

6. The condenser (10) according to any preceding claim, wherein the length (TL) of the tube (11) of the condenser (10) comprises at least two length sections, a first length section with a first at least partly varying cross-sectional shape (A, A', A", B, B', B", C, C', C") and a first at least partly varying inner volume and a second length section with a second at least partly varying cross-sectional shape (C, C', C", D, D', D", E, E', E", F, F', F") and a second at least partly varying inner volume, which first at least partly varying inner volume is larger than the second at least partly varying inner volume in the direction of flow of the refrigerant (1) from the first tube end (12) to the second tube end (13).

7. The condenser (10) according to claim 6, wherein the length (TL) of the tube (11) of the condenser (10) comprises at least a third or fourth or more length sections with at least partly varying third or fourth or more cross-sectional shapes (C, C', C", D, D', D", E, E', E", F, F', F") providing at least partly varying third or fourth or more inner volumes, respectively, being smaller than the first at least partly varying inner volume and / or the second at least partly varying inner volume of the first and / or second length sections in the direction of flow of the refrigerant (1) from the first tube end (12) to the second tube end (13).

8. The condenser (10) according to any preceding claim, wherein the lengthwise at least partly varying cross-sectional shape (A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F") of the tube (11) of the condenser (10) is configured to vary between the first tube end (12) and the second tube end (13), which at least partly varying cross-sectional inner shape and area is configured to provide an inner volume that at least partly decreases along the length (TL) of the tube (11) in the flow direction of the refrigerant (1) to the second tube end (13).

9. The condenser (10) according to any preceding claim, wherein the length (TL) of the tube (11) of the condenser (10) comprises at least two length sections providing a first length part forming half of the full length (TL) of the whole tube (11) and a second length part forming the other half of the full length of the whole tube (11), which first length part comprises a larger inner volume than the second length part of the length of the tube (11).

10. A method of manufacturing a condenser (10) for use in a heat pump system (100) to exchange heat between a refrigerant (1) and water (2) in a container (3), the condenser (10) comprising a tube (11) with two tube ends (12, 13) and a length (TL) therebetween for letting the refrigerant (1) through and a height (TH) in the vertical direction, the method comprising: introducing a first tube end (12, 13) into a tube forming machine (90, 90') before a second tube end is introduced therein, feeding the first tube end (12, 13) and the length (TL) of the tube (11) through the tube forming machine (90, 90') and forming the tube at least partly along at least a first section and a second section of the tube length (TL) into at least one or more varying cross-sectional shapes (A, A', A", B, B', B", C, C', C", D, D', D", E, E', E", F, F', F") and with at least two flat and opposite surfaces (14, 15) or with one inner flat surface (14) and one at least partly indented and / or at least partly flat outer surface (15) along at least a part of each tube length section, winding or coiling each tube length section into a helically shaped tube (11) around the shell of the container (3) with the flat inner surface (14) facing radially inwards forming an inner flat contact surface (14) substantially or fully in contact with a first area of the outer shell (CDo) of the container (3), and increasing the height (TH) of the helically shaped tube (11) along at least two length sections from lower to greater heights (TH) in the direction from the first tube end (12) to the second tube end (13).

11. The method of manufacturing a condenser (10) according to claim 10 comprising: winding or coiling each of the length sections into the helically shaped tube (11) around the container (3) with the inner flat contact surface (14) facing radially inwards and substantially or fully in contact with an area of the outer shell surface (CDo) of the container (3) being different from any outer area or shell area of the container that any other tube length section is winded or coiled around.

12. The method of manufacturing a condenser (10) according to claim 10 or 11, comprising: forming, by means of the tube forming machine (90, 90'), at least a first tube length section into a first varying cross-sectional shape (A, A', A", B, B', B", C, C', C") and a first varying inner volume of the first half of the length (TL) of the tube (11) and forming at least a second tube length section into a second varying cross-sectional shape (C, C', C", D, D', D", E, E', E", F, F', F") with a second varying inner volume of the second half of the tube length (TL), which second varying inner volume is smaller than the first varying inner volume of the first tube length section (A, B).

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