Mixing manifold for a hydronic system

Abstract

The present invention is directed to a mixing manifold (15) for a hydronic system (1), wherein the mixing manifold (15) comprises - a first fluid inlet (27), - a second fluid inlet (29), - a fluid outlet (31) having an outlet diameter (D), and - a mixing zone (33) extending from a mixing zone start point (35), where fluid coming from the second fluid inlet (29) starts mixing with fluid coming from the first fluid inlet (27), to a mixing zone end point (37), wherein the mixing zone (33) is shaped to guide all mixing fluid along a defined meandering mixing zone flow path comprising at least one turn of direction, wherein the mixing zone flow path has a mixing zone flow path length (L) that is at least three times longer than the outlet diameter (D), wherein the mixing zone end point (37) is defined as the most downstream of the at least one turn of direction of the meandering mixing zone flow path.

Description

[0001] Title: Mixing manifold fora hydronic system

[0002] Description

[0003] TECHNICAL FIELD

[0004]

[0001] The present invention refers to a mixing manifold for a hydronic system and a hydronic system with such a mixing manifold. A manifold is defined herein as a pipe or closed space in a hydronic system that has several openings, allowing a fluid to enter and leave. The hydronic system may, in particular, be a fluid distribution system for use in a heating, cooling, ventilating, and / or air-conditioning (HVAC) system of a building.

[0005] BACKGROUND

[0006]

[0002] For instance, the hydronic system may be a fluid distribution system for transporting thermal energy from a thermal energy source to a thermal energy consumer. In case of a heating system, for example, the heating system typically comprises a thermal energy source, a thermal energy consumer, a feed line being arranged downstream of the thermal energy source and upstream of the thermal energy consumer, a return line being arranged downstream of the thermal energy consumer and upstream of the thermal energy source, and a bypass line connecting the return line with the feed line. The bypass line is used to mix colder water from the return line back into the feed line to control the feed line temperature in a desired way. Although the hydronic system is described as a heating system in the following, a skilled reader will readily understand that a cooling system may have an analogous setup.

[0003] For example, EP 3 734 396 Bl describes such a known hydronic system in form of a domestic heating system. The bypass line typically enters the feed line at a T-joint or a 3-way-valve. A pump, located in the feed line downstream of an entry point of the bypass line into the feed line, drives the thermal energy flow towards the thermal energy consumer. It is an object to design an installation comprising the pump, a temperature sensor and a feed line valve around the entry point of the bypass line into the feed line as compact as possible. It is, however, a technical challenge to measure the feed line temperature correctly close to the entry point of the bypass line, because the colder water from the bypass line may not have properly mixed with the hotter water from the feed line at the temperature sensor. Known mixing devices being inserted into the pipe may be used to reduce the distance of the temperature sensor, but they have the disadvantage that they introduce high fluidic resistance that would cost increased power consumption of the pump.

[0007]

[0004] It is therefore an object of the present invention to allow a compact installation of the pump, the temperature sensor and the valve around the entry point of the bypass line into the feed line with a desired mixing degree at the temperature sensor while keeping an additional fluidic resistance low.

[0008] SUMMARY

[0009]

[0005] A solution to this problem is provided by a mixing manifold and a hydronic system according to the independent claims. Preferred embodiments of the inventive mixing manifold and hydronic systems can be deduced from the dependent claims, the description and the figures.

[0010]

[0006] According to a first aspect of the present invention, a mixing manifold for a hydronic system is provided, wherein the mixing manifold comprises: a first fluid inlet,

[0011] a second fluid inlet,

[0012] a fluid outlet having an outlet diameter, and

[0013] a mixing zone extending from a mixing zone start point, where fluid coming from the second fluid inlet starts mixing with fluid coming from the first fluid inlet, to a mixing zone end point,

[0014] wherein the mixing zone is shaped to guide all mixing fluid along a defined meandering mixing zone flow path comprising at least one turn of direction, wherein the mixing zone flow path has a mixing zone flow path length that is at least three times longer than the outlet diameter, wherein the mixing zone end point is defined as the most downstream one of the at least one turn of direction of the meandering mixing zone flow path.

[0015]

[0007] It is, therefore, the basic inventive idea of the present invention to replace an ordinary T-joint at the entry point of the bypass line into the feed line by a mixing manifold with a mixing zone that is shaped to guide all mixing fluid along a defined meandering mixing zone flow path. This allows a much more compact design of the installation that may comprise the pump, the temperature measurement arrangement, e.g. a temperature sensor, the valve and the mixing manifold while providing a mixing zone flow path length that is at least three times longer than the outlet diameter. Thereby, a desired mixing degree can be achieved at the mixing zone end point, where or downstream of which the temperature can be measured. On the one hand, the meandering mixing zone flow path has a better mixing effect and less space consumption than a straight pipe and, on the other hand, introduces much less fluidic resistance than a mixing device inserted in the pipe. The mixing zone flow path length may preferably be a sum of lengths of consecutive mixing zone flow path subsections, wherein preferably each mixing zone flow path subsection defines a flow vector direction that differs from the previous mixing zone flow path subsection.

[0008] The at least one turn of direction, preferably at least three turns of direction, of the meandering mixing zone flow path may for example be turns of flow vector direction by 90 degrees, 180 degrees and / or 360 degrees in one or more spatial planes. For instance, the meandering mixing zone flow path may follow a looping, a U-turn, and / or a curve with another shape in one or more spatial planes. If the fluid outlet of the mixing manifold is supposed to be coaxially aligned with the first fluid inlet of the mixing manifold, it is preferred that the vector sum of the flow vectors in all subsections of the meandering mixing zone flow path is zero in a plane, e.g. xy-plane, perpendicular to the coaxial axis, e.g. z-axis, of the first fluid inlet and the fluid outlet of the mixing manifold. Most preferably, the meandering mixing zone flow path comprises a total of five turns of direction including a U-turn that is arranged in a plane, e.g. yz-plane, being parallel, but laterally offset to a coaxial axis, e.g. z-axis, of the first fluid inlet and the fluid outlet of the mixing manifold. If a right-handed Cartesian coordinate system is defined with a z-axis extending along the coaxial axis of the first fluid inlet and the fluid outlet of the mixing manifold, an x-axis may be defined as the direction of the bypass flow towards the mixing zone start point, and a y-axis may extend along an actuator axis of the valve. The first, most upstream, of the five turns at the mixing zone start point may be in the yz-plane, the second of the five turns may be in the xy-plane, the third of the five turns may be a U-turn in the xz-plane, the fourth of the five turns may be in the xy-plane, and the fifth, most downstream, of the five turns at the mixing zone end point may be in the yz-plane.

[0016]

[0009] Preferably, the fluid coming from the second fluid inlet is at the mixing zone end point sufficiently mixed with fluid coming from the first fluid inlet to a desired mixing degree. Such a sufficient or desired mixing degree may be defined by a statistical mean deviation or variance of the outlet temperature to be small, e.g. below two degrees Celsius, while the temperature and flow at the first fluid inlet as well as the temperature and flow at the second fluid inlet are constant. An alternative definition may be that a difference between the highest and the lowest outlet temperature to be small, e.g. below five degrees Celsius, while the temperature and flow at the first fluid inlet as well as the temperature and flow at the second fluid inlet are constant.

[0017]

[0010] Optionally, the mixing manifold may further comprise at least one outlet fluid temperature sensor being arranged at or downstream of the mixing zone end point and at or upstream of the fluid outlet. Such an integration of the outlet fluid temperature sensor into the mixing manifold allows a more compact design. Alternatively, or in addition, the mixing manifold may comprise a lateral opening at the mixing zone end point to allow an extra fluid temperature sensor to be installed in and reaching through the lateral opening into the fluid to measure the fluid temperature at the mixing zone end point. This can be beneficial, for example, if the installation already comprises an extra temperature sensor, e.g. as part of the valve or the pump.

[0018]

[0011] Optionally, the mixing zone flow path length may be at least two times longer than a straight-line distance between the mixing zone start point and the outlet fluid temperature sensor. Such an embodiment is beneficial for a particularly compact design of the installation comprising a pump, a temperature sensor, a valve and the mixing manifold.

[0019]

[0012] Optionally, the mixing zone flow path length is less than or equal to eight times the outlet diameter. This is beneficial to not add too much hydraulic resistance by a too long mixing zone flow path length. The meandering form of the mixing zone flow path allows to design the mixing zone flow path length as short as possible for keeping the added hydraulic resistance as low as possible and to design it as long as necessary for achieving a desired mixing degree.

[0013] Optionally, a distance between the fluid outlet and any one of the first fluid inlet and the second fluid inlet is less than or equal to eight, preferably five, most preferably four, times the outlet diameter. This is advantageous to achieve an overall compact design of the mixing manifold.

[0020]

[0014] Optionally, the most upstream one of at least two turns of direction of the meandering mixing zone flow path may be located at the mixing zone start point (35). Thereby, a most compact design of the mixing zone can be achieved.

[0021]

[0015] Optionally, the first fluid inlet, the second fluid inlet and the fluid outlet are arranged in a T-configuration or a Y-configuration spanning a piping plane, e.g. xz-plane, wherein the first fluid inlet is preferably coaxially aligned with the fluid outlet. This is beneficial for installing the installation comprising the pump, the temperature sensor, the valve and the mixing manifold into a straight feed line.

[0022]

[0016] Optionally, the mixing zone flow path may comprise a first mixing zone flow path subsection, a second mixing zone flow path subsection downstream of the first mixing zone flow path subsection, a third mixing zone flow path subsection downstream of the second mixing zone flow path subsection and a fourth mixing zone flow path subsection downstream of the third mixing zone flow path subsection, wherein the first mixing zone flow path subsection extends from the mixing zone start point essentially perpendicular, e.g. in negative y-direction, to the piping xz-plane, wherein the second mixing zone flow path subsection extends essentially perpendicular, e.g. in x-direction, to the first mixing zone flow path subsection, wherein the third mixing zone flow path subsection extends essentially parallel, e.g. in negative x-direction, to the second mixing zone flow path subsection in reverse direction, and wherein the fourth mixing zone flow path subsection extends essentially parallel, e.g. in y- direction, to the first mixing zone flow path subsection in reverse direction. Preferably, one of at least three, preferably five, turns of direction of the meandering mixing zone flow path is a 180° U-turn, e.g. in the xz-plane, between the second mixing zone flow path subsection and the third mixing zone flow path subsection, wherein the length of the first mixing zone flow path subsection and the fourth mixing zone flow path subsection results in a lateral offset, e.g. in negative y-direction, of the U-turn with respect to the coaxial z-axis of the first fluid inlet and the fluid outlet. The U-turn thus extends preferably in a xz-plane parallel to the piping xz-plane, but laterally offset, e.g. in negative y-direction, from the coaxial z-axis of the first fluid inlet and the fluid outlet of the mixing manifold. Such a U-turn is compact and has a very effective mixing effect on the one hand and introduces less fluidic resistance than a mixing being inserted into the pipe.

[0023]

[0017] Optionally, the mixing manifold may comprise a flat wall section, wherein the flat wall section defines an outer wall surface of both the second mixing zone flow path subsection and the third mixing zone flow path subsection. The flat wall section has the advantage that the mixing manifold can be mounted close to a building wall, wherein the flat wall surface is parallel to and facing the building wall. The flat wall section preferably extends parallel to the piping xz-plane, but laterally offset, e.g. in negative y-direction, from the coaxial z-axis of the first fluid inlet and the fluid outlet of the mixing manifold.

[0024]

[0018] Optionally, the mixing manifold may comprise an inner separating wall section having no outer wall surface, wherein the inner separating wall section separates the second mixing zone flow path subsection from the third mixing zone flow path subsection and / or the first mixing zone flow path subsection from the fourth mixing zone flow path subsection. Preferably, the inner separating wall section has a first inner separating wall section surface defining an inner wall surface of the second mixing zone flow path subsection and a second inner separating wall section surface opposite to the first inner separating wall section surface, wherein the second inner separating wall section surface defines an inner wall surface of the third mixing zone flow path subsection. This is advantageous to save space and material for the mixing manifold. The inner separating wall section preferably extends in a xy-plane perpendicular to the coaxial z-axis of the first fluid inlet and the fluid outlet of the mixing manifold.

[0025]

[0019] Optionally, the mixing zone has a mixing zone diameter that is essentially constant along the full mixing zone flow path length. This is particularly beneficial to keep the hydraulic resistance of the mixing zone path at a minimum.

[0026]

[0020] According to another aspect of the present invention, a hydronic system is provided, wherein the hydronic system comprises

[0027] a mixing manifold as described above,

[0028] at least one outlet fluid temperature sensor,

[0029] a pump unit arranged downstream of the fluid outlet of the mixing manifold, and

[0030] a valve arrangement comprising one or more valves being arranged upstream of the first fluid inlet of the mixing manifold and / or upstream of the second fluid inlet of the mixing manifold, wherein an opening degree of the one or more valves defines an opening degree of a fluid path between the first fluid inlet to the fluid outlet and / or an opening degree of a fluid path between the second fluid inlet to the fluid outlet, wherein the at least one outlet fluid temperature sensor of the mixing manifold is arranged upstream of an inlet point of the pump unit.

[0031]

[0021] Optionally, the valve arrangement may comprise a 2-way-valve operation mode and / or a 3-way-valve operation mode. The valve ar- rangement in the 2-way-valve operation mode may comprise a non-re-turn valve in the bypass line in addition to a motor-controlled feed line valve. The valve arrangement in the 3-way-valve operation mode may comprise only a single valve with a valve body defining the entry point of the bypass line into the feed line.

[0032]

[0022] Optionally, the hydronic system may further comprise a housing accommodating a motor and control electronics for controlling the opening degree of at least one of the one or more valves.

[0033]

[0023] Optionally, the housing may have a height and a width defined in or parallel to a piping plane spanned by the first fluid inlet of the mixing manifold and the second fluid inlet of the mixing manifold, wherein the height and / or the width is larger than a straight-line distance between the mixing zone start point of the mixing manifold and the outlet fluid temperature sensor.

[0034]

[0024] Optionally, the hydronic system may further comprise a first inlet fluid temperature sensor being arranged at or downstream of the first fluid inlet of the mixing manifold an upstream of the mixing zone start point of the mixing manifold, and / or further comprising a second inlet fluid temperature sensor being arranged at or downstream of the second fluid inlet of the mixing manifold an upstream of the mixing zone start point of the mixing manifold.

[0035]

[0025] Optionally, the hydronic system may further comprise a thermal energy source, a thermal energy consumer, a feed line being arranged downstream of the thermal energy source and upstream of the thermal energy consumer, a return line being arranged downstream of the thermal energy consumer and upstream of the thermal energy source, and a bypass line connecting the return line with the feed line, wherein the pump unit is arranged to drive a thermal energy flow from the fluid outlet of the mixing manifold through the feed line towards the thermal energy consumer, wherein the return line is arranged to guide a return flow from the thermal energy consumer to the thermal energy source, and wherein the bypass line is arranged to guide a bypass flow from the return line into the second fluid inlet of the mixing manifold, wherein the valve arrangement is arranged in the feed line for controlling a thermal energy flow from the thermal energy source through the feed line into the first fluid inlet of the mixing manifold and / or the valve arrangement is arranged in the bypass line for controlling the bypass flow.

[0036] SUMMARY OF THE DRAWINGS

[0037]

[0026] Embodiments of the present invention will now be described by way of example with reference to the following figures of which:

[0038] Fig. 1 a shows schematically an example of a hydronic system according to the present invention in a 2-way-valve-configu- ration;

[0039] Fig. 1 b shows schematically an example of a hydronic system according to the present invention in a 3-way-valve-configu- ration;

[0040] Fig.2 shows an installation of an example of a hydronic system according to the present invention with a pump unit, a mixing manifold, an outlet fluid temperature sensor and a valve arrangement;

[0041] Fig.3 shows the installation of Fig. 3, wherein the housing of the valve arrangement for accommodating a motor and control electronics is discarded to allow a view on the temperature sensor, the mixing manifold and a valve body; Fig. 4a-d show the mixing manifold and the valve arrangement (without the housing) in four different side views;

[0042] Fig. 5 shows a perspective view of the mixing manifold including the outlet fluid temperature sensor;

[0043] Fig. 6a, b show different partial cut views of the mixing manifold including the outlet fluid temperature sensor;

[0044] Figs. 7a shows a cross-sectional view of a reference mixing manifold for comparison with the inventive mixing manifold shown in Fig. 7e;

[0045] Figs. 7b shows a cross-sectional view of a benchmark mixing manifold in form of a regular T-joint for comparison with the inventive mixing manifold shown in Fig. 7e;

[0046] Figs. 7c shows a cross-sectional view of another benchmark mixing manifold in form of a T-joint with an inserted mixing device for comparison with the inventive mixing manifold shown in Fig. 7e;

[0047] Figs. 7d shows a cross-sectional view of another benchmark mixing manifold in form of a T-joint with a wider diameter at the mixing zone start point for comparison with the inventive mixing manifold shown in Fig. 7e;

[0048] Figs. 7e shows a cross-sectional view of an embodiment of the inventive mixing manifold for comparison with the reference mixing manifold of Fig. 7a and the benchmark mixing manifolds of Figs. 7b-d; Figs. 8a, b shows tables with results of a simulated performance of the mixing manifolds according to Figs. 7a-e for different inlet conditions;

[0049] Figs. 9a, b shows tables with results of a simulated performance of the mixing manifolds according to Figs. 7a-e for other inlet conditions;

[0050] Fig. 10 shows a table with results of a simulated performance of the mixing manifolds according to Figs. 7a-e for yet other inlet conditions; and

[0051] Fig. 11 shows a cross-sectional view of another embodiment of the inventive mixing manifold.

[0052] DETAILED DESCRIPTION

[0053]

[0027] Fig. 1a shows schematically a domestic heating system as an example for a hydronic system I according to the present invention. A skilled reader will understand that the domestic heating system is just one possible example of an inventive hydronic system I. The hydronic system I may alternatively be a cooling system or another hydronic system for transporting thermal energy from a thermal energy source (not shown in Figs. la,b) to a thermal energy consumer 3. A feed line 5 is arranged downstream of the thermal energy source and upstream of the thermal energy consumer 3 for transporting thermal energy from the thermal energy source to the thermal energy consumers. A return line 7 is arranged downstream of the thermal energy consumer 3 and upstream of the thermal energy source for recirculating the fluid used for transporting the thermal energy. A bypass line 9 connects the return line 7 with the feed line 5 to mix a certain fraction of the return flow through the return line 7 as a bypass flow through the bypass line 9 into the feed line 5.

[0054]

[0028] The thermal energy flow through the feed line 5 to the thermal energy consumer 3 is determined by the flow and the temperature of the fluid in the feed line 5 downstream of the entry point of the bypass line 9 into the feed line 5. The flow of the fluid within the feedline downstream of the entry point of the bypass line 9 into the feedline 5 is driven by a pump unit 11 arranged downstream of the entry point of the bypass line 9 into the feed line 5. The pump unit 11 is part of an installation 13 of the hydronic system 1, wherein the installation 13 comprises the pump unit 11, a mixing manifold 15, an outlet fluid temperature sensor 17, an inlet fluid temperature sensor 19 and a valve arrangement 21a, b. In the 2-way-valve-configuration of the valve arrangement 21a, b shown in Fig. la, the valve arrangement 21a, b comprises two separate valves, a mo-tor-controlled feed line valve 21a arranged in the feed line 5 upstream of the entry point of the bypass line 9 into the feed line 5, and a nonreturn valve 21b arranged in the bypass line 9 to prevent a reversed flow through the bypass line 9 from the feed line 5 to the return line 7. The inlet fluid temperature sensor 19 is optional and may be integrated into the mixing manifold or arranged upstream or downstream of the feed line valve 21 a.

[0055]

[0029] Fig. 1b shows a 3-way-valve-configuration of the valve arrangement 21a, b, wherein the entry point of the bypass line 9 into the feed line 5 is the motor-controlled 3-way feed line valve 21a. A non-return valve 21b as shown in Fig. 1a may not be needed in the bypass line 5 in the 3-way-valve-configuration of the feed line valve 21 a as shown in Fig.

[0056] 1 b. As in Fig. 1 a, the inlet fluid temperature sensor 19 is optionally installed in the feed line 5 upstream of the feed line valve 21a. The outlet fluid temperature sensor 17 is installed in the feed line 5 upstream of the pump unit 11 and downstream of the feed line valve 21a. The feed line valve 21a may be integrated into the mixing manifold as shown in the 3-way-valve-configuration shown in Fig. 1b. In the 2-way-valve-configuration shown in Fig. 1a, the mixing manifold 15 is arranged downstream of the feed line valve 21a and the non-return valve 21 b, but upstream of the pump unit 11. The outlet fluid temperature sensor 17 may be integrated into the mixing manifold 15 or arranged in the feed line 5 downstream of the mixing manifold 15, but upstream of the pump unit 11.

[0057]

[0030] Fig. 2 shows as an example an embodiment of the installation 13 in the 2-way-valve-configuration, wherein the non-return valve 21 b is not shown. The feed line valve 21 a comprises here a housing 23 accommodating a motor and control electronics for controlling the position of a movable valve body 25 (see Fig. 3) of the feed line valve 21a. In Fig. 2, the mixing manifold 15 is not visible underneath the housing 23 of the feed line valve 21 a.

[0058]

[0031] In Fig. 3, the housing 23 of the feed line valve 21 a is not shown to allow a view on the mixing manifold 15 and the valve body 25 of the feed line valve 21a. The compact mixing manifold 15 defines the entry point of the bypass line 9 into the feed line 5. The feed line 5 and the bypass line 9 span a piping plane xz extending in parallel to the paper plane of Fig. 3.

[0059]

[0032] To make the orientation in the figures easier, the figures comprise a right-handed Cartesian coordinate system, wherein the z-axis is defined as the axis along which the feed line 5 extends. The x-axis is defined as the axis along which the bypass line 9 extends. Thus, the x-axis and the z-axis span the piping plane xz. The y-axis is directed perpendicular to the piping plane xz towards the observer of Figs. 2 and 3. The installation 13 may typically be installed at a building wall extending parallel to the piping plane xz. The z-axis may then extend vertically, while the x-axis and the y-axis extend horizontally. A skilled reader will understand that the installation 13 may have any desired spatial orientation.

[0060]

[0033] It should be noted that the piping diameter of the installation 13 may be DN20 or below, wherein DN stands for diametre nominate (frz and corresponds a standardised nominal inner piping diameter of % inch, i.e. 21,6 mm, or below. Accordingly, the pump unit 11 may be a relatively small and basic circulator pump. The pump unit 11 does not need to have an integrated temperature sensor.

[0061]

[0034] What makes the installation 13 particularly compact in z-direction is the mixing manifold 15 that defines the entry point of the bypass line 9 into the feed line 5. The mixing manifold 15 comprises a first fluid inlet 27, a second fluid inlet 29, a fluid outlet 31 and a mixing zone 33. In the embodiment shown in Figs. 2-6a,b, the outlet fluid temperature sensor 17 is integrated into the mixing manifold 15. Alternatively, the outlet fluid temperature sensor may be arranged downstream of the fluid outlet 31 of mixing manifold 15 and upstream of the pump unit 11.

[0062]

[0035] The first fluid inlet 27 of the mixing manifold 15 is connected to an outlet of the feed line valve 21a for receiving a valve-controlled flow of a heat-transferring fluid from the feed line 5. The first fluid inlet 27 is here directed into the negative z-direction. The second fluid inlet 29 of the mixing manifold 15 is designated to be connected to the bypass line 9 for guiding a bypass flow of the heat-transferring fluid from the return line 7 in the x-direction into the mixing manifold 15. The second fluid inlet 29 of the mixing manifold 15 is therefore directed towards the negative x-direction. The fluid outlet 31 of the mixing manifold 15 is coaxially aligned with the first fluid inlet 27 of the mixing manifold 15 and is directed to the positive z-direction to guide the mixed heat-transferring fluid into an inlet of the pump unit 11. An outlet of the pump unit 11 is connected to the feed line 5 that guides the mixed heat-transferring fluid towards the thermal energy consumer s. The first fluid inlet 27 of the mixing manifold 15 has a first inlet diameter, the second fluid inlet 29 of the mixing manifold 15 has a second inlet diameter and the fluid outlet 31 of the mixing manifold 15 has an outlet diameter D. In the shown embodiment, the first inlet diameter, the second inlet diameter and the outlet diameter D are all identical and may be standardized, e.g. DN20, DN15 or DN10. The outlet diameter D (see Fig. 6a) may be an inner pipe diameter of 21,6 mm or less. In the shown example, the first fluid inlet 27, the second fluid inlet 29 and the fluid outlet 31 each comprise a union nut with a standardized inner thread to connect the feed line valve 21a to the first fluid inlet 27 of the mixing manifold 15, the bypass line 9 to the second fluid inlet 29 of the mixing manifold, and the pump unit 11 to the fluid outlet 31 of the mixing manifold 15.

[0063]

[0036] The mixing manifold 15 may be made of plastic and / or composite being casted or made by injection moulding. Figs. 4a-c show the installation 13 without the pump unit 11 from different angles. Fig. 4a shows a bottom view into positive z-direction, Fig. 4b shows a front view in negative y-direction, Fig. 4c shows a left side view in negative x-direction and Fig. 4d shows a rear view in positive y-direction. It becomes clear from the Figs. 4a-d that the mixing zone 33 of the mixing manifold 15 has a specific shape to facilitate mixing of the heat-transferring fluid coming from the feed line 5 with the heat transferring fluid coming from the bypass line 9 while introducing as little fluidic resistance as possible. The mixing zone 33 extends from a mixing zone start point 35 where fluid coming from the second fluid inlet 29 starts mixing with fluid coming from the first fluid inlet 27, to a mixing zone end point 37, where fluid coming from second fluid inlet 29 is supposed to be sufficiently mixed with fluid coming from the first fluid inlet 27 to a desired mixing degree. Both, the mixing zone start point 35 and the mixing zone end point 37 are in the shown embodiments located on the z-axis coaxially with the feed line 5 and have an axial distance in z-direction that is less than twice the outlet diameter D (see Fig. 6a). This is very beneficial to achieve a very compact design, in particular in z-direction.

[0064]

[0037] To achieve the desired mixing degree at the mixing zone end point 37, the mixing zone 33 is shaped to guide all mixing fluid along a defined meandering mixing zone flow path comprising five turns of direction in the shown embodiments, wherein the mixing zone flow path has a mixing zone flow path length L that is at least three times longer than the outlet diameter D. The mixing zone end point 37 is defined as the most downstream of the turns of direction before the mixed fluid reaches the fluid outlet 31. There is thus no turn of direction between the mixing zone end point 37 and the fluid outlet 31. To keep the hydraulic resistance of the mixing zone flow path low, the mixing zone flow path length L is preferably less than or equal to eight times the outlet diameter D. The mixing zone flow path length L may be a sum of lengths of consecutive mixing zone flow path subsections, wherein each mixing zone flow path subsection may define a flow vector direction that differs from the previous mixing zone flow path subsection. The outlet fluid temperature sensor 17 is arranged at or downstream of the mixing zone end point 37. Thereby, the outlet fluid temperature sensor 17 measures the temperature of the sufficiently mixed fluid before it leaves the mixing manifold 15 through the fluid outlet 31 into the pump unit 11. A desired mixing degree may, in the shown embodiments, be defined such that a difference between the highest and the lowest measured temperature among n > 10 test sample temperature measurements of the outlet fluid temperature sensor 17 is low, e.g. below five degrees Celsius, while the temperature and flow at the first fluid inlet 27 as well as the temperature and flow at the second fluid inlet 29 are constant over the n > 10 test sample temperature measurements. Thereby, the temperature measurement of the outlet fluid temperature sensor 17 is essentially independent of its position in the cross-sectional xy-plane.

[0038] Figs. 5 and 6a, b show only the mixing manifold 15 with the integrated outlet fluid temperature sensor 17 in more detail. As can be seen, the mixing zone flow path length L is at least two times longer than a straight-line distance A between the mixing zone start point 35 and the outlet fluid temperature sensor 17. In the shown example, the meandering mixing zone flow path comprises five turns of direction, of which each has a mixing effect. The most upstream first turn of direction is located at the mixing zone start point 35, where the mixing fluid is guided into a first mixing zone flow path subsection 39 extending in negative y-direction. So, the mixing fluid is first guided orthogonal to the piping plane xz spanned by the first fluid inlet 27, the second fluid inlet 29 and the fluid outlet 31 that are arranged in a T-configuration. The most upstream first turn of direction is therefore a 90°-turn for both, the feed line flow and the bypass flow. The second turn is also a 90°-turn into a second mixing zone flow path subsection 41 extending in positive x-direction downstream of the first mixing zone flow path subsection 39. It follows a 180°-turn in the xz-plane into a third mixing zone flow path subsection 43 that extends parallel to the second mixing zone flow path subsection 41 into negative x-direction. The fourth turn of direction is another 90°-turn into a fourth mixing zone flow path subsection 45 extending in positive y-direction towards the mixing zone end point 37. The most downstream last turn of direction at the mixing zone end point 37 is another 90°-turn into positive z-direction towards the outlet fluid temperature sensor 17 and the fluid outlet 31. In total, the mixing zone flow path has a mixing zone flow path length L extending from the mixing zone start point 35 to the mixing zone end point 37 that is at least three times longer than the outlet diameter D.

[0065]

[0039] As can be seen in Figs.4b, 4c and 6a, the mixing manifold 15 comprises a flat wall section 47 defining an outer wall surface of both the second mixing zone flow path subsection 41 and the third mixing zone flow path subsection 43. The flat wall section 47 also defines an outer wall surface of the 180°-turn between the second mixing zone flow path subsection 41 and the third mixing zone flow path subsection 43. This is beneficial for reducing the space consumption in y-direction for mounting the installation 13 as close to a building wall as possible. Furthermore, the mixing zone 33 of the mixing manifold 15 can be easily manufactured by injection moulding without lost cores. After the mixing zone is injection moulded without the flat wall section 47, the flat wall section 47 may be fused with the mixing zone 33 to close the back of the second mixing zone flow path subsection 39, of the third mixing zone flow path subsection 43, and of the 180°-turn.

[0066]

[0040] The mixing manifold 15 further comprises an inner separating wall section 49 that has no outer wall surface and extends in the xy-plane. The inner separating wall section 49 separates the second mixing zone flow path subsection 39 and the third mixing zone flow path subsection 43. This saves material and space consumption, in particular in z-direc-tion.

[0067]

[0041] Figs. 7a-e, 8a, b, 9a, b and 10 show how the inventive mixing manifold 15 as shown in Fig. 7e performs in comparison to a reference mixing manifold 15’ shown in Fig. 7a and three benchmark mixing manifolds 15’ shown in Figs. 7b-d. It should be noted that the reference mixing manifold 15’ shown in Fig. 7a and three benchmark mixing manifolds 15’ shown in Figs. 7b-d are just shown for reference and performance comparison; they do not show embodiments of the invention.

[0068]

[0042] Fig 7a shows a reference mixing manifold 15’ in form of a T-joint with a large extension in z-direction, so that the straight mixing zone extends in z-direction over a mixing zone path length L of ten times the outlet diameter D. It can be assumed that a desired mixing degree is reached by such a long mixing zone path length L. Therefore, the mixing manifold 15’ shown in Fig. 7a may serve as a reference for the performance of the inventive mixing manifold 15 shown in Fig. 7e.

[0069]

[0043] Fig. 7b shows a first benchmark mixing manifold 15’ in form of an ordinary T-joint. Fig. 7c shows a second benchmark mixing manifold 15’ in form of a T-joint with a mixing device inserted to narrow the fluid flow. Fig. 7d shows a third benchmark mixing manifold 15’ in form of a T-joint with a wider cross-section at the mixing zone start point 35’. Fig. 7e shows an embodiment of the inventive mixing manifold 15 that is very similar to the embodiment shown in Figs. 2-6a,b.

[0070]

[0044] Fig. 8a shows a table with results of a simulated performance of the mixing manifolds 15’, 15 according to Figs. 7a-e for equal mass flows of 0.15 kg / s through the first fluid inlet 27 and through the second fluid inlet 29, wherein the fluid temperature at the first fluid inlet 27 is 60°C and the fluid temperature at the second fluid inlet 29 is 30°C. The temperature of the ideally mixed fluid Tided should be 45°C at the fluid outlet 31. The simulation runs 100 test sample temperature measurements by the outlet fluid temperature sensor 17 located at or just downstream of the mixing zone end point 37, where the temperature of the mixed fluid should have the temperature Tided of 45°C. The table contains the lowest measured temperature Tmin and the highest measured temperature Tmax among the 100 test sample measurements. A temperature spread of AT=T max-T min is also given in the table. Furthermore, the pressure loss Ap over the mixing zone path length L from the mixing zone start point 35 to the mixing zone end point 37 is also simulated. To account for a compactness of the mixing manifold 15’, 15, the table gives further a ratio L / D, i.e. the mixing zone path length L divided by the outlet diameter D.

[0071]

[0045] The performance of the mixing manifolds 15’, 15 can be indicated by certain performance indicators, which are also given in the table and may be defined as follows: a) A relative deviation from Tidealwith Tmin,ref and Tmax,ref being the lowest and highest measured temperatures of the reference mixing manifold shown

[0072]

[0073] which is a measure for how well the ideal temperature is reached at the mixing zone end point 37 compared to the reference mixing manifold 15’ of Fig. 7a.

[0074] b) A relative reference temperature spread with Tref being the temperature spread of the reference mixing manifold 15’ of Fig. 7a:

[0075]

[0076] which is a measure for the mixing degree at the mixing zone end point 37 compared to the reference mixing manifold 15’ of Fig. 7a.

[0077] c) A relative pressure loss with pref being the pressure loss of the reference mixing manifold 15’ of Fig. 7a:

[0078]

[0079] which is a measure for how much pressure loss the mixing zone adds compared to the reference mixing manifold 15’ of Fig. 7a.

[0080] d) A relative mixing zone path length L with Lrefbeing the mixing zone path length of the reference mixing manifold 15’ of Fig. 7a:

[0081] RL= ——,

[0082] ref

[0083] which is a measure for the compactness compared to the reference mixing manifold 15’ of Fig. 7a.

[0084]

[0046] A total performance indicator may be defined as an average of all the above-defined performance indicators, e.g. (RTiI

[0085]

[0086] I RL), given in the last row of the table shown in Fig. 8a. A skilled reader will readily understand that a total performance indicator may be defined in many ways, which may weigh the individual performance indicators equally or differently. With the average shown in the tables, the total performance indicator below 1 indicates a better overall performance than the reference mixing manifold 15’ of Fig. 7a. A total performance indicator above 1 indicates a worse overall performance compared to the reference mixing manifold 15’ of Fig. 7a. The table of Fig. 8a shows clearly that the inventive mixing manifold 15 of Fig. 7e has the best total performance with a lowest total performance indicator of 0.46.

[0087]

[0047] Fig. 8b shows the results of a simulated performance of the mixing manifolds 15’, 15 according to Figs. 7a-e for equal mass flows of 0.15 kg / s through the first fluid inlet 27 and through the second fluid inlet 29, wherein the fluid temperature at the first fluid inlet 27 is 50°C and the fluid temperature at the second fluid inlet 29 is 40°C. So, the initial temperature difference is lower compared to Fig. 8a. Also for these initial conditions, the inventive mixing manifold 15 of Fig. 7e has the best total performance with a lowest total performance indicator of 0.36.

[0088]

[0048] Both, the first benchmark mixing manifold 15’ of Fig. 7b and the third benchmark mixing manifold 15’ of Fig. 7d do not have a sufficient mixing effect. The mixing effect of the second benchmark mixing manifold 15’ of Fig. 7c is better, but has the disadvantage of adding a lot of pressure loss.

[0089]

[0049] Figs. 9a, b show the results of a simulated performance of the mixing manifolds 15’, 15 according to Figs. 7a-e for different mass flows of 0.05 kg / s and 0.25 kg / s, respectively, through the first fluid inlet 27 and through the second fluid inlet 29, wherein the fluid temperature at the first fluid inlet 27 is 60°C and the fluid temperature at the second fluid inlet 29 is 30°C. Also for these initial conditions, the inventive mixing manifold 15 of Fig. 7e has the best total performance with a lowest total performance indicator of 0.04 and 0.08.

[0050] Fig. 10 shows the results of a simulated performance of the mixing manifolds 15’, 15 according to Figs. 7a-e for equal mass flows of 0.3 kg / s through the first fluid inlet 27 and through the second fluid inlet 29, wherein the fluid temperature at the first fluid inlet 27 is 60°C and the fluid temperature at the second fluid inlet 29 is 30°C. So, the total initial flow is doubled compared to Figs. 8a, b and 9a, b. Also for these initial conditions, the inventive mixing manifold 15 of Fig. 7e has the best total performance with a lowest total performance indicator of 0.28.

[0090]

[0051] In the embodiment of the inventive mixing manifold 15 shown in Figs. 2, 3, 4a-d, 5, 6a-b and 7e, the mixing zone 33 has a mixing zone diameter that is essentially equal to the outlet diameter D. Fig. 11 shows an embodiment of the inventive mixing manifold 15, wherein the mixing zone 33 has a mixing zone diameter B that is larger than the outlet diameter D. The advantage of a larger mixing zone diameter B is that the fluid velocity in the mixing zone is reduced to increase the mixing time in the mixing zone. Thereby, the mixing effect is improved without adding significant fluidic resistance. To keep the hydraulic resistance at a minimum, it is for all embodiments of the inventive mixing manifold 15 advantageous if the mixing zone diameter B is essentially constant along the full mixing zone flow path length L.

[0091]

[0052] Where, in the foregoing description, integers orelements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the disclosure that are described as optional, preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

[0053] The above embodiments are to be understood as illustrative examples of the disclosure. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. While at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art and may be changed without departing from the scope of the subject matter described herein, and this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0092]

[0054] In addition, "comprising" does not exclude otherelements or steps, and "a" or "one" does not exclude a plural number. Furthermore, characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other characteristics or steps of other exemplary embodiments described above. Method steps may be applied in any order or in parallel or may constitute a part or a more detailed version of another method step. It should be understood that there should be embodied within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of the contribution to the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the disclosure, which should be determined from the appended claims and their legal equivalents.

[0093]

[0055] List of reference numerals:

[0094] 1 hydronic system

[0095] 5 feed line

[0096] 7 return line

[0097] 9 bypass line 11 pump unit

[0098] 13 installation

[0099] 15 mixing manifold

[0100] 17 outlet fluid temperature sensor

[0101] 19 inlet fluid temperature sensor

[0102] 21a feed line valve

[0103] 21 b non-return valve

[0104] 23 housing

[0105] 25 valve body

[0106] 27 first fluid inlet

[0107] 29 second fluid inlet

[0108] 31 fluid outlet

[0109] 33 mixing zone

[0110] 35 mixing zone start point

[0111] 37 mixing zone end point

[0112] 39 first mixing zone flow path subsection

[0113] 41 second mixing zone flow path subsection

[0114] 43 third mixing zone flow path subsection

[0115] 45 fourth mixing zone flow path subsection

[0116] 47 flat wall section

[0117] 49 inner separating wall section

[0118] A straight-line distance between mixing zone start point and outlet temperature sensor

[0119] D outlet diameter

[0120] L mixing zone path length

[0121] B mixing zone diameter

Claims

Claims1. A mixing manifold ( 15) for a hydronic system ( 1 ), wherein the mixing manifold (15) comprisesa first fluid inlet (27),a second fluid inlet (29),a fluid outlet (31 ) having an outlet diameter (D), anda mixing zone (33) extending from a mixing zone start point (35), where fluid coming from the second fluid inlet (29) starts mixing with fluid coming from the first fluid inlet (27), to a mixing zone end point (37),wherein the mixing zone (33) is shaped to guide all mixing fluid along a defined meandering mixing zone flow path comprising at least one turn of direction, wherein the mixing zone flow path has a mixing zone flow path length (L) that is at least three times longer than the outlet diameter (D), wherein the mixing zone end point (37) is defined as a most downstream one of the at least one turn of direction of the meandering mixing zone flow path.

2. The mixing manifold ( 15) according to claim 1, further comprising at least one outlet fluid temperature sensor ( 17) being arranged at or downstream of the mixing zone end point (37) and at or upstream of the fluid outlet (31 ).

3. The mixing manifold ( 15) according to any of the preceding claims, wherein the mixing zone flow path length (L) is less than or equal to eight times the outlet diameter (D).

4. The mixing manifold ( 15) according to any of the preceding claims, wherein a distance between the fluid outlet (31) and any one of the first fluid inlet (27) and the second fluid inlet (29) is less than or equal to eight, preferably five, times the outlet diameter (D).

5. The mixing manifold ( 15) according to any of the preceding claims, wherein a most upstream of at least two turns of direction of the meandering mixing zone flow path is located at the mixing zone start point (35).

6. The mixing manifold ( 15) according to any of the preceding claims, wherein the first fluid inlet (27), the second fluid inlet (29) and the fluid outlet (31) are arranged in a T-configuration or a Y-configura- tion spanning a piping plane (xz), wherein the first fluid inlet (27) is preferably coaxially aligned with the fluid outlet (31 ).

7. The mixing manifold (15) according to claim 6, wherein the mixing zone flow path comprises a first mixing zone flow path subsection (39), a second mixing zone flow path subsection (41) downstream of the first mixing zone flow path subsection (39), a third mixing zone flow path subsection (43) downstream of the second mixing zone flow path subsection (41) and a fourth mixing zone flow path subsection (45) downstream of the third mixing zone flow path subsection (43), wherein the first mixing zone flow path subsection (39) extends from the mixing zone start point (35) essentially perpendicular to the piping plane (xz), wherein the second mixing zone flow path subsection (41) extends essentially perpendicular to the first mixing zone flow path subsection (39), wherein the third mixing zone flow path subsection (43) extends essentially parallel to the second mixing zone flow path subsection (41 ) in reverse direction, and wherein the fourth mixing zone flow path subsection (45) extends essentially parallel to the first mixing zone flow path subsection (39) in reverse direction.

8. The mixing manifold (15) according to claim 7, wherein the mixing zone flow path comprises at least three turns of direction, one ofwhich is a 180°-turn between the second mixing zone flow path subsection (41 ) and the third mixing zone flow path subsection (43).

9. The mixing manifold (15) according to claim 7 or 8, comprising an inner separating wall section (49) having no outer wall surface, wherein the inner separating wall section (49) separates the second mixing zone flow path subsection (41) from the third mixing zone flow path subsection (43) and / or the first mixing zone flow path subsection (39) from the fourth mixing zone flow path subsection (45).

10. The mixing manifold ( 15) according to any of the preceding claims, wherein the mixing zone (33) has a mixing zone diameter (B) that is equal to or larger than the outlet diameter (D).

11. The mixing manifold ( 15) according to any of the preceding claims, wherein the mixing zone (33) has a mixing zone diameter (B) that is essentially constant along the full mixing zone flow path length (L).

12. A hydronic system ( 1 ) comprisinga mixing manifold (15) according to any of the preceding claims,at least one outlet fluid temperature sensor ( 17),a pump unit (11) arranged downstream of the fluid outlet (31 ) of the mixing manifold (15), anda valve arrangement (21 a, b) comprising one or more valves (21 a, b) being arranged upstream of the first fluid inlet (27) of the mixing manifold (15) and / or upstream of the second fluid inlet (29) of the mixing manifold (15), wherein an opening degree of the one or more valves (21 a, b) defines an opening degree of a fluid path from the first fluid inlet (27) to the fluid outlet (31) and / or an opening degree of a fluid path from the second fluid inlet (29) to the fluid outlet (31), wherein the at least one outletfluid temperature sensor (17) of the mixing manifold (15) is arranged upstream of an inlet port of the pump unit (11).

13. The hydronic system (1) according to claim 12, wherein the valve arrangement (21 a, b) comprises a 2-way-valve operation mode and / or a 3-way-valve operation mode.

14. The hydronic system (1) according to claim 12 or 13, further comprising a housing (23) accommodating a motor and control electronics for controlling the opening degree of at least one of the one or more valves (21 a, b), wherein the housing (23) has a height and a width defined in or parallel to a piping plane (xz) spanned by the first fluid inlet (27) of the mixing manifold (15) and the second fluid inlet (29) of the mixing manifold ( 15), wherein the height and / or the width is larger than a straight-line distance (A) between the mixing zone start point (35) of the mixing manifold ( 15) and the outlet fluid temperature sensor (17).

15. The hydronic system (1) according to any of the claims 12 to 14, further comprising a first inlet fluid temperature sensor (19) being arranged at or downstream of the first fluid inlet (27) of the mixing manifold ( 15) and upstream of the mixing zone start point (35) of the mixing manifold (15), and / or further comprising a second inlet fluid temperature sensor (19) being arranged at or downstream of the second fluid inlet (29) of the mixing manifold (15) and upstream of the mixing zone start point (35) of the mixing manifold (15).

16. The hydronic system (1) according to any of the claims 12 to 15, further comprising a thermal energy source, a thermal energy consumer (3), a feed line (5) being arranged downstream of the thermal energy source and upstream of the thermal energy consumer(3), a return line (7) being arranged downstream of the thermal energy consumer (3) and upstream of the thermal energy source, and a bypass line (9) connecting the return line (7) with the feed line (5), wherein the pump unit (11) is arranged to drive a thermal energy flow from the fluid outlet (31 ) of the mixing manifold ( 15) through the feed line (5) towards the thermal energy consumer (3), wherein the return line (7) is arranged to guide a return flow from the thermal energy consumer (3) to the thermal energy source, and wherein the bypass line (9) is arranged to guide a bypass flow from the return line (7) into the second fluid inlet (29) of the mixing manifold (15), wherein the valve arrangement (21 a, b) is arranged in the feed line (5) for controlling a thermal energy flow from the thermal energy source through the feed line (5) into the first fluid inlet (27) of the mixing manifold (15) and / or the valve arrangement (21 a, b) is ar-ranged in the bypass line (9) for controlling the bypass flow.

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