Condenser tube, heat transfer method, and heat exchange device

Abstract

The invention relates to a condenser tube profile 7 and a method and a device for heat exchange, in which the condenser tube profile 7 is applied for heat exchange purposes. The condenser tube profile 7 is made from aluminum or an aluminum alloy in an extrusion process, and a heat transfer medium is conveyed through one or more channels 12 arranged in said tube profile 7. A substantially flat flange 11 is integrated into the tube profile. The tube profile can be wound in a helical shape on the outer surface of an object 8, preferably having a cylindrical shape, the flat flange being firmly attached to the surface of the object. The invention also relates to a method of heat transfer 9 between a heat transfer medium flowing through such a condenser tube and a liquid 4 in a tank, and to an apparatus, such as a domestic water heater made of steel or stainless steel, in which this heat transfer arrangement is provided.

Description

[Technical field]

[0001] The present invention relates to a condenser tube, a heat transfer method and a heat exchange device in which the condenser tube is applied to circulate a heat transfer medium for heat exchange purposes. More specifically, the present invention relates to a condenser tube profile having one or more channels and a certain shape, which can be spirally wound on the outside of a metal container or tank for heat transfer purposes, for example, for heating domestic water. [Background technology]

[0002] A common technology used today to transfer heat to liquids contained in steel or stainless steel tanks, such as hot water heat pumps, is based on round, flat or D-shaped aluminum condenser tubes that are wrapped around the tank. Due to the poor thermal conductivity of steel and stainless steel, heat does not spread far from the contact point of the tube and the tank. In order to transfer sufficient heating energy to the liquid (water) in the tank, the condenser tubes are wound close to each other and over a larger part of the tank. Therefore, the length of the round / flat / D-shaped condenser tubes needs to be somewhat long, often 50 meters to 60 meters. Therefore, due to this length, the cross-flow range of the round / flat / D-shaped condenser tubes needs to be somewhat large so as not to cause a large pressure drop in the cooling cycle, which is energy inefficient. This solution is good enough, since HFC refrigerant gases are currently available without GWP (global warming potential) constraints / quota regulations.

[0003] Patent Document 1 discloses a high-efficiency cooling condenser pipe of a cooler, which aims to solve the shortcomings of conventional condenser tubes. The high-efficiency cooling condenser pipe of Patent Document 1 includes a heat induction part and a radiation cooling part, the heat induction part contacts the inner wall of the cooler body, and the radiation cooling part is connected to the heat induction part. The preferred shape of the condenser pipe of Patent Document 1 is an Ω shape welded at the bottom opening. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] China Patent Publication No. 107525311 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need for a heat transfer pipe that allows a reduction in the refrigerant injection amount to meet future regulations on refrigerant gases and provide a more sustainable solution. Furthermore, the reduced refrigerant injection amount increases the safety of the equipment. At the same time, it is desirable that the energy efficiency (COP) of the heat exchanger is not reduced compared to current technologies, but rather that the energy efficiency is equal to or greater than that of the current best-performing technologies. [Means for solving the problem]

[0006] According to a first aspect, the present disclosure provides a condenser tube profile made of aluminum or an aluminum alloy arranged on the outside of a substantially cylindrical shaped object, the condenser tube profile providing heat transfer between a medium conveyed inside at least one channel of the condenser tube profile having an inner diameter (ID) and a medium, preferably a liquid, contained within the object, the condenser tube profile being wrapped around the outer surface of the object, the condenser tube profile having an integrated substantially flat flange having a flange width (FW) parallel to the longitudinal direction of the condenser tube, the flange being arranged in thermal contact with the outer surface of the object.

[0007] The at least one channel may have a substantially round shape with the flange integral with its periphery.

[0008] The flange may be thinner on its outer side than adjacent the at least one channel and may have a sloping surface towards its longitudinal side edges.

[0009] The condenser tube section may be wound in a helical configuration having a pitch such that one side edge of the flange abuts the other side edge.

[0010] The condenser tube section is preferably extruded by an extrusion process and wound into a coil.

[0011] The object may be a steel or stainless steel tank or container.

[0012] The condenser tube section may be provided with two channels.

[0013] The relationship between the inner diameter (ID) of the channel and the flange width (FW), ie the ratio ID:FW, may be in the interval 2mm-6mm:20mm-65mm.

[0014] Alternatively, the relationship between the inner diameter (ID) of the channel and the flange width (FW), ie the ratio ID:FW, may be in the interval 2.5mm-5mm:22.5mm-60mm.

[0015] In a further alternative, the relationship between the inner diameter (ID) of the channel and the flange width (FW), ie the ratio ID:FW, may be in the interval 3mm-4.5mm:22.5mm-55mm.

[0016] According to a second aspect, the present disclosure provides a method for transferring heat between a heat transfer medium and a medium, preferably a liquid such as water, contained in a substantially cylindrical tank made of steel or stainless steel, wherein a condenser tube profile made of aluminum or an aluminum alloy guides the heat transfer medium in one or more channels and is further arranged outside the tank, said condenser tube profile is provided with a substantially flat flange on its periphery, the sides of said flange extending parallel to said condenser tube profile in the longitudinal direction of said condenser tube profile, said flange of said condenser tube is attached in firm contact with said tank, and said condenser tube is wound in a helical shape.

[0017] The condenser tube section may be wound in a helical configuration having a pitch such that one side of the flange abuts or substantially abuts the other side of the flange.

[0018] The heat transfer medium is preferably a hydrocarbon refrigerant and the injection volume of the refrigerant system is preferably up to 150g.

[0019] According to a third aspect, the present disclosure relates to the use of a condenser tube profile of the first aspect, wherein the condenser tube guides a heat transfer medium into one or more channels, and the condenser tube profile is arranged on an outer surface of a cylindrical tank for heating water.

[0020] The heat transfer medium is preferably a hydrocarbon refrigerant and the injection volume of the refrigerant system is preferably up to 150g.

[0021] According to a fourth aspect, the present disclosure provides an apparatus for heating domestic water, comprising a cylindrical tank made of steel or stainless steel for water to be heated, a condenser tube made of aluminum or an aluminum alloy is fixed on an outer surface of the cylindrical tank for heating the water by a heat transfer medium (refrigerant) flowing through one or more channels of the condenser tube, the condenser tube being provided with a substantially flat flange on its periphery, the flange having side edges extending parallel to the condenser tube in the longitudinal direction of the condenser tube, the condenser tube being wound in a helical shape around the surface of the tank and being attached in firm contact with the surface of the tank.

[0022] The condenser tube section may be wound in a helical configuration having a pitch such that one side of the flange abuts or substantially abuts the other side of the flange.

[0023] The heat transfer medium (refrigerant) flowing through the one or more channels of the condenser tube section is preferably a hydrocarbon refrigerant, and the injection volume of the refrigerant system is preferably up to 150 g.

[0024] According to the invention, the condenser tube can be made from aluminum or an aluminum alloy in a single extrusion step with one or more channels. Furthermore, the extruded tube profile is provided with a flange integrated on its periphery. The flange has a flat surface in contact with the tank. The flat surface in contact with the tank ensures good mechanical and thermal contact between the flanged condenser tube and the tank when the flanged condenser tube is tightly coiled around the flat surface of the tank. The large contact area between the tube flange and the tank minimizes the thermal contact resistance between the flanged tube and the tank and therefore optimizes the substantially one-dimensional heat transfer from the flanged tube to the liquid inside the tank.

[0025] The cross-sectional shape of the condenser tube profile may be circular with a substantially flat flange, so that it has a closed, albeit Ω-shaped, shape. The substantially round channel shape with flanges integrated around its periphery may withstand an internal pressure increase with minimal distortion of its shape and substantially no deformation of the flange, thus maintaining good thermal contact between the flanged tube profile and the tank. The flange should be thick enough to withstand deformation during coiling and pressurization. The flange may be thinner on its outside than near the channel(s), so that it has a sloping surface towards its longitudinal side edges.

[0026] By winding the condenser tubes on the outer surface of the tank in which the fluid is heated, with a winding pitch that brings the long sides of the flanges closer together or abutting each other, a very efficient heat transfer can be obtained with a small amount of cooling medium required for the circulation circuit. One advantageous field of use of the condenser tubes is that they can be placed on the outer surface of cylindrical tanks for heating water for domestic use.

[0027] These and further advantages may be achieved by the present invention as defined in the accompanying claims 1 to 19.

[0028] The invention is explained in further detail below by way of example and with reference to the accompanying figures 1 to 8. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 shows a cross-section of a tank with the condenser tubes outside the tank, illustrating the current technology used today, which is based on round, flattened or D-shaped tubes that are wrapped around the tank. [Diagram 2] FIG. 2 is a cross-sectional view of a tank with a condenser tube profile having one channel and further comprising a flange and wrapped around the outside of the tank, according to one embodiment of the present invention. [Diagram 3] FIG. 2 shows a condenser tube profile with flanges according to the invention having one channel. [Figure 4] FIG. 2 shows a condenser tube profile with flanges according to the invention, further provided with two channels. [Diagram 5] FIG. 5 discloses a means for connecting the flanged tube of FIG. 4 to a circuit. [Figure 6] FIG. 1 illustrates a range of dimensions for various channels and flanges according to the present invention. [Figure 7a] FIG. 1 illustrates heat transfer in a current art D-tube heater. [Figure 7b] FIG. 1 illustrates heat transfer for a flanged tube of the present invention. [Figure 8] FIG. 1 is a diagram briefly illustrating a clean water heater using a round or D-shaped pipe (left) and a clean water heater using a flanged pipe according to the present invention (right). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present disclosure will now be described with reference to the accompanying drawings, in which preferred exemplary embodiments of the present disclosure are illustrated. However, the present disclosure may be embodied in other forms and should not be construed as being limited to the embodiments disclosed herein. The disclosed embodiments are provided to fully convey the scope of the present disclosure to those skilled in the art.

[0031] FIG. 1 is a cross-section of a tank with the condenser tubes outside the tank, and discloses the current technology used today, based on a round, flat or D-shaped tube 1 (shown with four turns) wrapped around a steel or stainless steel tank 2. Due to the poor thermal conductivity of steel / stainless steel, the heat is not distributed far from the contact point 3 of the tube with the tank. To transfer sufficient heating energy to the water 4 in the tank, the tubes are wrapped close to each other (5) and over a larger part of the tank. This is also shown on the left side of FIG. 8. Therefore, the length of the round / D-shaped tube needs to be somewhat long, often 50 meters to 60 meters. Therefore, the cross-flow range 6 of the round / flat / D-shaped tube needs to be somewhat large so as not to create a large pressure drop in the cooling cycle, which is energy inefficient. This requires a certain amount of heat transfer medium in the circuit.

[0032] Figure 2 discloses a double wrap of condenser tube profile 7 made from aluminium or its alloys and provided with flanges 10, 11 according to the invention, wrapped around a steel or stainless steel tank 8. The tank can contain a large amount of water 4. The good thermal conductivity properties of aluminium allow heat to be transferred from the channel 12 to the flange 11, as indicated by the arrow 9, with minimal constraints between the parts.

[0033] As disclosed in FIG. 3, the flange 11' of the condenser tube profile 7' according to the present invention covers a larger area of ​​the tank with sufficient surface contact, thus minimizing the effects of the poor thermal conductivity of steel / stainless steel and of the contact between the tank and the flange.

[0034] The large width of the flange 11' associated with the condenser tube profile provided with the channels 12' for the heat transfer medium allows the number of turns around the tank to be reduced, as shown on the right side of Fig. 8, and therefore the tubular section can be significantly shortened, for example to 18-23 meters, which corresponds to a length two to three times shorter than the commonly used solutions. The condenser tube can be wound in a helical shape, advantageously with a pitch such that the sides of the flange abut against each other over the entire length of the helix, in order to cover the tank surface as much as possible.

[0035] Preferably, the aluminum or aluminum alloy is of A6xxx, A3xxx or A1xxx type, preferably A3xxx or A1xxx type, which has ductility that allows the condenser tube of the present invention to be easily formed into a spiral with the flange of the condenser tube flat against the cylindrical surface of the tank. (References in this disclosure to A1xxx, A3xxx and A6xxx series aluminum alloys are to the Aluminum Association nomenclature, which uses a four-digit classification system for wrought alloy composition families (see "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys" by The Aluminum Association, Inc.). The medium in the tank may be a liquid, preferably water.

[0036] The radius 13 between the round section and the flange should preferably be located close to the outer diameter and have a certain size, such as about 0.5 mm (but not limited to this value), to minimize the heat transfer distance from the coolant channel to the outer tip of the flange. This design also helps to facilitate the extrusion process. Furthermore, together with the robust flange thickness, this design minimizes deformation of the flat pipe flange during coiling after extrusion.

[0037] One technical advantage of the significantly shorter tubing provided by the present invention is that it allows for a significant reduction in cross-sectional flow area without introducing a significant overall pressure drop in the refrigeration cycle.

[0038] The flanged condenser tube sections may be much shorter than the prior art and may have a smaller inside diameter than the prior art, allowing for a reduction in internal volume without compromising performance parameters.

[0039] As a result, this (the condenser tube profile of the present invention) allows for the use of low GWP (global warming potential) gases, such as hydrocarbons, at system injection amounts up to and including 150 grams.

[0040] Figure 4 shows an alternative design of a condenser tube profile 7'' with a flange 11'' according to the invention, which is further provided with two channels 12'', 12'''. This design can be provided by one extruded profile, making it possible to reduce the cross-sectional flow area.

[0041] FIG. 5 discloses a means for connecting the condenser tube section 7'' having two channels 12'', 12'' of FIG. 4 to a circuit comprising a yoke-shaped tube with a main tube 16 having branch tubes 17, 18.

[0042] FIG. 6 discloses a diagram illustrating the range of dimensions of the various channels and flanges according to the present invention, indicated by three rectangular areas. Here, the relationship between the inner diameter ID of the channel and the flange width FW, i.e., the ratio ID:FW, is within the interval of (2 mm~6 mm):(20 mm~65 mm); Or ID:FW is within the range of (2.5mm~5mm):(22.5mm~60mm), Or ID:FW is within the interval of (3mm-4.5mm):(22.5mm-55mm).

[0043] Figure 7a shows the heat transfer in a heater using a current state of the art D-shaped tube, and Figure 7b shows the heat transfer for the flanged tube of the present invention. The arrows indicate the heat transfer, and as can be seen from the illustration in Figure 7b, the heat transfer is very uniform.

[0044] Figure 8 briefly discloses a clean water heater using a round or D-shaped tube (left) and a clean water heater using a flanged tube according to the present invention (right). In the right explanatory diagram, it can be seen that the number of times the tube is wound is greatly reduced.

[0045] For example, simply increasing the flange width provides several benefits. Fewer turns around the tank shortens the overall length of the tube, which allows for less coolant injection and therefore less pressure drop in the cooling system. On the other hand, increasing the flange width increases the distance the energy (heat) has to travel to reach the flange tip, which may slightly reduce the total heat transfer into the tank (e.g., the water being heated).

[0046] Reducing the inner diameter of the tube (channel 12) offers several advantages, such as reducing the amount of coolant injected, but a possible disadvantage is an increased pressure drop in the cooling system.

[0047] test A clean hot water heat pump system using the flanged pipe profile of the invention with an inner diameter ID=φ4.5 mm and a flange width FW=25 mm was tested according to EN 16147 with a propane (R290) injection of 150 g. The obtained COP=3.63 was a considerable improvement over the COP=3.15 of a conventional system with a round flat φ10×1 condenser tube with 900 g of R134a (a standard HFC refrigerant). For reference, a conventional system with a round flat φ10×1 condenser tube was also tested with 350 g of R290, resulting in a COP=3.52.

[0048] Conclusions from the pilot study: The energy efficiency (COP) using the flanged condenser pipe profile of the present invention can be increased to approximately 3.6 to 3.8 when the amount of propane (R290) injected into the system in a typical clean hot water heat pump system is 150g. Therefore, the flanged condenser pipe profile of the present invention reduces the amount of R290 injected to 150g, which is within the safety limit, and improves the COP to approximately the same level as that of a high-performance general system using HFC refrigerant gas.

[0049] The energy efficiency (COP) can be further improved by reducing the inner diameter / widening the flange (combined with optimizing / reducing the internal volume of the evaporator) and it can operate with up to 150g propane.

[0050] Additionally, the present invention allows for a reduction in the amount of material used in manufacturing condenser tubes compared to current art tubes.

[0051] As an example, for a φ10×1 mm round or D-shaped aluminum tube, approximately 77 g / m×55.6 meters, i.e. 4.29 kg of aluminum per tube, is required. For an aluminum flanged condenser tube profile according to the present invention with ID=φ5 mm and flange width=25 mm, approximately 140 g / m×23 meters, i.e. 3.22 kg of aluminum per tube, is required. Thus, the aluminum flanged condenser tube profile according to the present invention is also a more sustainable solution in terms of the significantly reduced material required.

[0052] The condenser tube profile may be extruded over its entire length and may be coiled during production.

Claims

1. A condenser tube profile (7, 7', 7'') made of aluminum or an aluminum alloy, arranged on the outside of a substantially cylindrical object (8), said condenser tube profile (7, 7', 7'') effecting heat transfer between a medium conveyed inside at least one channel (12) of said condenser tube profile (7, 7', 7'') having an inside diameter (ID) and a medium, preferably a liquid, contained within said object (8), said condenser tube profile (7, 7', 7'') being wrapped around the outer surface of said object (8), A condenser tube profile, characterized in that a substantially flat flange (11) having a flange width (FW) is integrated parallel to the longitudinal direction of the condenser tube, said flange being arranged in thermal contact with said outer surface of said body (8).

2. 2. Condenser tube profile according to claim 1, wherein said at least one channel (12) has a substantially round shape with said flange (11) integrated on its periphery.

3. 3. A condenser tube profile according to claim 1 or 2, wherein the flange (11) is thinner on its outer side than in the vicinity of the at least one channel (12) and has a sloping surface towards its longitudinal side edges.

4. 3. The condenser tube profile according to claim 1 or 2, wherein the condenser tube profile (7, 7', 7'') is wound in a helical shape having a pitch such that one side edge of the flange abuts the other side edge.

5. Condenser tube profile according to claim 1 or 2, wherein the condenser tube profile (7, 7', 7'') is made by an extrusion process.

6. 2. The condenser tube profile according to claim 1, wherein the object (8) is a tank or container made of steel or stainless steel.

7. Condenser tube profile according to claim 1 or 2, characterized in that the condenser tube profile (7'') is provided with two channels (12'', 12''').

8. 3. Condenser tube profile according to claim 1 or 2, wherein the condenser tube profile (7, 7', 7'') is extruded and wound into a coil.

9. 3. The condenser tube profile according to claim 1 or 2, wherein the relationship (ID):(FW) between the inner diameter (ID) of the channel (12, 12', 12'', 12''') and the flange width (FW) is in the interval (ID):(FW) of (2mm-6mm):(20mm-65mm).

10. 10. The condenser tube profile of claim 9, wherein the relationship (ID):(FW) between the inner diameter (ID) of the channel (12, 12', 12'', 12''') and the flange width (FW) is in the interval (ID):(FW) of (2.5mm-5mm):(22.5mm-60mm).

11. The condenser tube profile according to claim 10, wherein the relationship (ID):(FW) between the inner diameter (ID) of the channel (12, 12', 12'', 12''') and the flange width (FW) is in the interval (ID):(FW) of (3mm-4.5mm):(22.5mm-55mm).

12. A method for transferring heat between a heat transfer medium and a medium, preferably a liquid, contained in a substantially cylindrical tank (8) made of steel or stainless steel, comprising: a condenser tube profile (7, 7', 7'') made of aluminum or an aluminum alloy, which guides the heat transfer medium in one or more channels (12) and is further arranged outside the tank; 13. The method of claim 12, wherein the condenser tube profile (7, 7', 7'') is provided with a substantially flat flange (11) on the periphery of the condenser tube profile (7, 7', 7''), the sides of which run parallel to the condenser tube profile (7, 7', 7'') in the longitudinal direction of the condenser tube profile (7, 7', 7''), the flange (11) of the condenser tube is attached in firm contact with the tank (2), and the condenser tube is wound in a helical shape.

13. 13. The method according to claim 12, wherein the condenser tube section (7, 7', 7'') is wound in a helical shape having a pitch such that one side of the flange abuts or substantially abuts the other side of the flange.

14. 14. The method according to claim 12 or 13, wherein the heat transfer medium is a hydrocarbon refrigerant and the injection amount of the refrigerant system is up to 150 g.

15. 3. Use of a condenser tube profile (7, 7', 7'') according to claim 1 or 2, in which the condenser tube guides a heat transfer medium into one or more channels (12), and the condenser tube profile (7, 7', 7'') is arranged on the outer surface of a cylindrical tank (8) for heating water.

16. 16. Use of a condenser tube profile (7, 7', 7'') according to claim 15, wherein the heat transfer medium is a hydrocarbon refrigerant and the injection quantity of the refrigerant system is up to 150 g.

17. A device for heating domestic water, comprising a cylindrical tank (8) made of steel or stainless steel for the water to be heated, with condenser tube profiles (7, 7', 7'') made of aluminum or an aluminum alloy fixed on the outer surface of the cylindrical tank (8) for heating the water by a heat transfer medium flowing through one or more channels (12) of the condenser tube profiles (7, 7', 7''), 4. The apparatus according to claim 3, wherein the condenser tube profile (7, 7', 7'') is provided on its periphery with a substantially flat flange (11), said flange having side edges extending parallel to the condenser tube profile in the longitudinal direction of the condenser tube profile, and wherein the condenser tube profile (7, 7', 7'') is wound in a helical shape around the surface of the tank (8) and is attached in firm contact with the surface of the tank (8).

18. 18. Apparatus according to claim 17, wherein the condenser tube section (7, 7', 7'') is wound in a helical shape having a pitch such that one side of the flange abuts or substantially abuts the other side of the flange.

19. 19. Apparatus according to claim 17 or 18, wherein the heat transfer medium flowing through the one or more channels (12) of the condenser tube section (7, 7', 7'') is a hydrocarbon refrigerant and the injection amount of the refrigerant system is up to 150 g.

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