Heat exchanger header construction for hvac systems
By adopting a vertical flow design and multiple pass-through loops in the heat exchanger of the HVAC system, the problem of oil retention in the manifold design is solved, achieving uniform distribution of refrigerant and effective oil return, thus improving the stability and safety of the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CARRIER CORP
- Filing Date
- 2026-01-21
- Publication Date
- 2026-07-24
AI Technical Summary
In existing HVAC systems, the manifold design of heat exchangers is prone to creating liquid refrigerant stagnation zones under low refrigerant mass flow conditions, leading to oil retention and consequently causing insufficient compressor oil.
The design employs a vertical flow pattern at the inlet and outlet of the heat exchanger, combined with the main manifold path and manifold branches, and the U-shaped bend of the capillary tube, forming multiple pass-through loops to ensure uniform distribution and collection of refrigerant within the heat exchanger and reduce oil retention.
It effectively reduces oil retention, ensures uniform refrigerant distribution, and improves system operational stability, especially under low flow conditions, reducing the risk of highly flammable refrigerants.
Smart Images
Figure CN122447831A_ABST
Abstract
Description
Technical Field
[0001] Exemplary embodiments relate to the field of heat exchangers. More specifically, this disclosure relates to manifold configurations for heat exchangers. Background Technology
[0002] Heating, ventilation, and air conditioning (HVAC) systems utilize heat exchangers, such as condensers and evaporators. A heat exchanger has multiple channels through which refrigerant flows and has manifolds to distribute the refrigerant into the channels at the heat exchanger inlet and to collect the refrigerant from the channels at the heat exchanger outlet.
[0003] Typical manifolds for heat exchangers are closed at the vertical bottom and utilize centrally located inlets / outlets to facilitate refrigerant distribution to the various channels of the heat exchanger. Under certain operating conditions, such as low refrigerant mass flow rates, this configuration can create a liquid refrigerant stagnation zone at the bottom of the manifold due to stratification. This stratification also creates an oil stagnation zone within the refrigerant circuit, potentially leading to insufficient compressor oil due to a lack of oil return from the compressor. Summary of the Invention
[0004] In one exemplary embodiment, a heat exchanger for a heating, ventilation, and air conditioning (HVAC) system includes a plurality of heat exchange paths extending across a heat exchanger body, and a heat exchanger inlet oriented such that a refrigerant flow flows vertically upward through the heat exchanger inlet to an inlet manifold configured to distribute the refrigerant flow to the plurality of heat exchange paths. A heat exchanger outlet is connected to the plurality of heat exchange paths. The heat exchanger outlet is oriented such that a refrigerant flow exiting the heat exchanger via the heat exchanger outlet flows vertically upward through the heat exchanger outlet.
[0005] Alternatively or in this embodiment or other embodiments, the inlet manifold includes a main manifold path extending vertically from the heat exchanger inlet, and a plurality of manifold branches extending from the main manifold path to connect to a plurality of heat exchange paths.
[0006] Alternatively or in this embodiment or other embodiments, a plurality of capillaries are connected to the heat exchanger outlet via one of a nozzle or a venturi tube.
[0007] Additionally or alternatively, in this embodiment or other embodiments, the capillary in the plurality of capillaries includes a U-shaped bend between the plurality of heat exchange paths and one of the nozzles or venturi tubes.
[0008] Alternatively or in this embodiment or other embodiments, multiple heat exchange tubes are interconnected to form multiple loops, and each of the multiple loops is connected to the heat exchanger inlet and the heat exchanger outlet.
[0009] Alternatively or in this embodiment or other embodiments, at least one of the multiple loops is a multiple-pass loop, which includes two or more of the multiple heat exchange tubes.
[0010] Alternatively or in this embodiment or other embodiments, the heat exchanger inlet and heat exchanger outlet are located at the same end of the heat exchanger.
[0011] Alternatively or in this embodiment or other embodiments, the heat exchanger is one of the condensers or evaporators of the HVAC system.
[0012] In another exemplary embodiment, a heating, ventilation, and air conditioning (HVAC) system includes a vapor compression cycle, the vapor compression cycle including at least one heat exchanger. The heat exchanger includes a plurality of heat exchange paths extending across a heat exchanger body, and a heat exchanger inlet oriented such that a refrigerant flow flows vertically upward through the heat exchanger inlet to an inlet manifold, the inlet manifold being configured to distribute the refrigerant flow to the plurality of heat exchange paths. A heat exchanger outlet is connected to the plurality of heat exchange paths. The heat exchanger outlet is oriented such that a refrigerant flow exiting the heat exchanger via the heat exchanger outlet flows vertically upward through the heat exchanger outlet.
[0013] Alternatively or in this embodiment or other embodiments, the inlet manifold includes a main manifold path extending vertically from the heat exchanger inlet, and a plurality of manifold branches extending from the main manifold path to connect to a plurality of heat exchange paths.
[0014] Alternatively or in this embodiment or other embodiments, a plurality of capillaries are connected to the heat exchanger outlet via one of a nozzle or a venturi tube.
[0015] Additionally or alternatively, in this embodiment or other embodiments, the capillary in the plurality of capillaries includes a U-shaped bend between the plurality of heat exchange paths and one of the nozzles or venturi tubes.
[0016] Alternatively or in this embodiment or other embodiments, multiple heat exchange tubes are interconnected to form multiple loops, and each of the multiple loops is connected to the heat exchanger inlet and the heat exchanger outlet.
[0017] Alternatively or in this embodiment or other embodiments, at least one of the multiple loops is a multiple-pass loop, which includes two or more of the multiple heat exchange tubes.
[0018] Alternatively or in this embodiment or other embodiments, the heat exchanger inlet and heat exchanger outlet are located at the same end of the heat exchanger.
[0019] Alternatively or in this embodiment or other embodiments, the heat exchanger is one of the condensers or evaporators of the HVAC system.
[0020] In yet another exemplary embodiment, a heating, ventilation, and air conditioning (HVAC) system includes a refrigerant circuit comprising a compressor, a condenser, an expander, and an evaporator. The condenser includes a plurality of heat exchange paths extending across a heat exchanger body, and a heat exchanger inlet oriented such that a refrigerant flow through the heat exchanger inlet flows vertically upward toward an inlet manifold configured to distribute the refrigerant flow to the plurality of heat exchange paths. A heat exchanger outlet is connected to the plurality of heat exchange paths. The heat exchanger outlet is oriented such that a refrigerant flow exiting the heat exchanger via the heat exchanger outlet flows vertically upward through the heat exchanger outlet.
[0021] Alternatively or in this embodiment or other embodiments, the inlet manifold includes a main manifold path extending vertically from the heat exchanger inlet, and a plurality of manifold branches extending from the main manifold path to connect to a plurality of heat exchange paths.
[0022] Alternatively or in this embodiment or other embodiments, a plurality of capillaries are connected to the heat exchanger outlet via one of a nozzle or a venturi tube.
[0023] Alternatively or in this embodiment or other embodiments, the heat exchanger inlet and heat exchanger outlet are located at the same end of the heat exchanger. Attached Figure Description
[0024] The following description should not be considered as a limitation of any kind. Referring to the accompanying drawings, similar elements are similarly numbered: Figure 1 This is a schematic diagram of an embodiment of a vapor compression cycle in a heating, ventilation, and air conditioning (HVAC) system; Figure 2 This is a schematic diagram of the condenser in an HVAC system; Figure 3 This is a schematic diagram of the evaporator in an HVAC system; and Figure 4 This is a schematic diagram of an exemplary embodiment of the inlet and outlet arrangement of a heat exchanger in an HVAC system. Detailed Implementation
[0025] This document will present a detailed description of one or more embodiments of the disclosed devices and methods by way of example, rather than limitation, with reference to the accompanying drawings.
[0026] For reference Figure 1This diagram schematically illustrates a vapor compression refrigerant cycle 20 for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system. Exemplary HVAC&R systems include, but are not limited to, split-type, integrated, chiller-type, rooftop, supermarket, and transport-type HVAC&R systems. The refrigerant R is configured to circulate through the vapor compression cycle 20 such that the refrigerant R absorbs heat when evaporating at low temperature and low pressure, and releases heat when condensing at higher temperature and higher pressure.
[0027] Within this vapor-compression refrigerant cycle 20, the refrigerant flows counterclockwise as indicated by the arrow. Compressor 22 receives refrigerant vapor from evaporator 24 and compresses it to a higher temperature and pressure. The relatively hot vapor is then conveyed to condenser 26, where it is cooled and condensed into a liquid state through heat exchange with a cooling medium (not shown), such as air. The liquid refrigerant R is then conveyed from condenser 26 to expansion unit 28, where it expands into a low-temperature liquid / gas two-phase state as it was conveyed to evaporator 24. The low-pressure vapor then returns to compressor 22, where the cycle repeats. Compressor lubricant (such as oil) entrained in the refrigerant also returns from evaporator 24 to compressor 22.
[0028] For reference Figure 2 A heat exchanger, as shown, operates as the condenser 26 of the vapor-compressing refrigerant cycle 20. Although Figure 2 The heat exchanger is shown operating as a condenser 26, but it is reversible, allowing it to operate as an evaporator 24 in other embodiments. The condenser 26 includes a heat exchanger body 29 through which a plurality of heat exchanger tubes 30 or other heat exchanger paths extend. Refrigerant R is directed through the plurality of heat exchanger tubes 30. A heat exchanger manifold 32 distributes the refrigerant R from a condenser inlet 34 to the plurality of condenser tubes 30. In some embodiments, the heat exchanger manifold 32 may include a main manifold path 36 and a plurality of manifold branches 38 extending from the main manifold path 36 and connecting the heat exchanger manifold 32 to the plurality of heat exchanger tubes 30.
[0029] In condenser mode, once the refrigerant R has been delivered through the multiple heat exchanger tubes 30, it is collected in multiple capillary tubes 40 connected to the heat exchanger tubes 30. For example, nozzles 42 or venturi tubes are connected to the multiple capillary tubes 40 to collect the refrigerant R from them and guide it to the condenser outlet 44 and towards the expansion device 28. In some embodiments, such as Figure 2As shown, the heat exchanger manifold 32, the plurality of capillaries 40, and the nozzles 42 are all positioned at the same axial end of the heat exchanger. However, those skilled in the art will readily understand that this arrangement is merely exemplary, and in other embodiments, the heat exchanger manifold 32 and the plurality of capillaries 40 may be located, for example, at opposite ends of the heat exchanger.
[0030] For reference Figure 3 When the heat exchanger operates as evaporator 24, the flow of refrigerant R is substantially reversed, and refrigerant R is delivered from expansion device 28 through nozzle 42 and distributed to multiple heat exchanger tubes 30 via multiple capillary tubes 40. Then, refrigerant R is collected at heat exchanger manifold 32 and directed to compressor 22.
[0031] Refer again Figure 2 The heat exchanger tubes 30 are arranged in multiple loops 46, and each loop 46 is a multiple-pass loop 46, wherein the refrigerant R flows at least once from the first heat exchanger end 50 to the second heat exchanger end 52 along the first direction 48, and the refrigerant R flows at least once along the second direction 54 opposite to the first direction 48.
[0032] For reference Figure 4 The arrangement of the heat exchanger manifold 32 and capillary tube 40, as well as an exemplary circuit 46, are shown in more detail. The exemplary circuit 46 is a six-tube circuit 46 and includes connected heat exchanger tubes 30a, 30b, 30c, 30d, 30e, and 30f. Heat exchanger tube 30a is connected to a manifold branch 38 of the heat exchanger manifold 32, through which refrigerant R is guided into circuit 46. Figure 4 As shown, each manifold branch 38 is similarly connected to a corresponding loop 46 among a plurality of loops 46. Heat exchanger tubes 30a, 30b, 30c, 30d, 30e, and 30f are interconnected (in some embodiments, via U-shaped connectors 56) such that refrigerant R flows sequentially through heat exchanger tubes 30a, 30b, 30c, 30d, 30e, and 30f. Refrigerant R flows from heat exchanger tube 30f along a corresponding capillary tube 40 among a plurality of capillaries 40, through nozzle 42, and exits at condenser outlet 44. Although the exemplary loop 46 described herein has six heat exchanger tubes 30, those skilled in the art will readily understand that other loops 46 may have other numbers of heat exchanger tubes 30.
[0033] The heat exchanger manifold 32 is positioned such that the main manifold path 36 is vertical, and the condenser inlet 34 is positioned at the vertical bottom end of the main manifold path 36. In this orientation, refrigerant R flows vertically upward from the condenser inlet 34 along the main manifold path 36 and is distributed to multiple manifold branches 38. Furthermore, in some embodiments, the condenser outlet 44 is oriented such that refrigerant R exiting the condenser outlet 44 flows vertically upward. To achieve this, multiple capillary tubes 40 may each include a U-shaped bend 58. Therefore, the flow direction of refrigerant R into the condenser inlet 34 is the same as the flow direction of refrigerant R exiting the condenser outlet 44.
[0034] This configuration reduces oil retention in the condenser 26, where oil typically tends to accumulate (e.g., during low-mass-flow operation of cycle 20, it can accumulate in areas such as heat exchanger manifold 32). This excess refrigerant R is now removed via the condenser inlet 32. This avoids dead zones while still allowing refrigerant R to be distributed as desired to the multiple heat exchanger tubes 30. Furthermore, the required amount of oil in the refrigerant loop can be reduced, and therefore the amount of refrigerant can also be reduced due to the dissolution effect, which can be significant when using highly flammable refrigerants. Finally, this configuration passively returns the oil from the heat exchanger manifold 32 to the compressor 22 via gravity flow.
[0035] The term “approximately” is intended to include the degree of error associated with measurements of a specific number based on equipment available at the time of application submission.
[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly specifies otherwise. It will be further understood that, as used in this specification, the terms “comprising” and / or “including” specify the presence of the said feature, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.
[0037] Although this disclosure has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made to this disclosure without departing from its scope, and its elements can be substituted with equivalents. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of this disclosure without departing from its essential scope. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed as the best mode contemplated for carrying out this disclosure, but that this disclosure will include all embodiments falling within the scope of the claims.
Claims
1. A heat exchanger for a heating, ventilation, and air conditioning (HVAC) system, comprising: Multiple heat exchange paths extending across the heat exchanger body; A heat exchanger inlet is oriented such that a refrigerant flow is vertically upward through the heat exchanger inlet to an inlet manifold, the inlet manifold being configured to distribute the refrigerant flow to the plurality of heat exchange paths; as well as A heat exchanger outlet, which is connected to the plurality of heat exchange paths, is oriented such that the refrigerant flow exiting the heat exchanger via the heat exchanger outlet flows vertically upward through the heat exchanger outlet.
2. The heat exchanger according to claim 1, wherein, The inlet manifold includes: The main manifold path extends vertically from the inlet of the heat exchanger; and Multiple manifold branches extend from the main manifold path to connect to the multiple heat exchange paths.
3. The heat exchanger according to claim 1, wherein, Multiple capillaries are connected to the heat exchanger outlet via a nozzle or a venturi tube.
4. The heat exchanger according to claim 3, wherein, The capillary in the plurality of capillaries includes a U-shaped bend between the plurality of heat exchange paths and one of the nozzles or venturi tubes.
5. The heat exchanger according to claim 3 or 4, wherein: The plurality of heat exchange tubes are interconnected to form a plurality of loops; and each of the plurality of loops is connected to the heat exchanger inlet and the heat exchanger outlet.
6. The heat exchanger according to claim 5, wherein, At least one of the plurality of loops is a multiple-pass loop, which includes two or more of the plurality of heat exchange tubes.
7. The heat exchanger according to claim 1, wherein, The heat exchanger inlet and the heat exchanger outlet are located at the same end of the heat exchanger.
8. The heat exchanger according to claim 1, wherein, The heat exchanger is one of the condensers or evaporators in the HVAC system.
9. A heating, ventilation, and air conditioning (HVAC) system, comprising: A vapor compression cycle comprising at least one heat exchanger, said heat exchanger comprising: Multiple heat exchange paths extending across the heat exchanger body; A heat exchanger inlet, oriented such that a refrigerant flow is vertically upward through the heat exchanger inlet to an inlet manifold, the inlet manifold being configured to distribute the refrigerant flow to the plurality of heat exchange paths; and A heat exchanger outlet, which is connected to the plurality of heat exchange paths, is oriented such that the refrigerant flow exiting the heat exchanger via the heat exchanger outlet flows vertically upward through the heat exchanger outlet.
10. The HVAC system according to claim 9, wherein, The inlet manifold includes: The main manifold path extends vertically from the inlet of the heat exchanger; and Multiple manifold branches extend from the main manifold path to connect to the multiple heat exchange paths.
11. The HVAC system according to claim 9, wherein, The plurality of capillaries are connected to the heat exchanger outlet via one of the nozzles or venturi tubes.
12. The HVAC system according to claim 11, wherein, The capillary in the plurality of capillaries includes a U-shaped bend between the plurality of heat exchange paths and one of the nozzles or venturi tubes.
13. The HVAC system according to claim 11 or 12, wherein: The plurality of heat exchange tubes are interconnected to form a plurality of loops; and each of the plurality of loops is connected to the heat exchanger inlet and the heat exchanger outlet.
14. The HVAC system according to claim 13, wherein, At least one of the plurality of loops is a multiple-pass loop, which includes two or more of the plurality of heat exchange tubes.
15. The HVAC system according to claim 9, wherein, The heat exchanger inlet and the heat exchanger outlet are located at the same end of the heat exchanger.
16. The HVAC system according to claim 9, wherein, The heat exchanger is one of the condensers or evaporators in the HVAC system.
17. A heating, ventilation, and air conditioning (HVAC) system, comprising: The refrigerant circuit includes: compressor; Condenser; Expansion device; and Evaporator; The condenser includes: Multiple heat exchange paths extending across the heat exchanger body; A heat exchanger inlet, oriented such that a refrigerant flow is vertically upward through the heat exchanger inlet to an inlet manifold, the inlet manifold being configured to distribute the refrigerant flow to the plurality of heat exchange paths; and A heat exchanger outlet, which is connected to the plurality of heat exchange paths, is oriented such that the refrigerant flow exiting the heat exchanger via the heat exchanger outlet flows vertically upward through the heat exchanger outlet.
18. The HVAC system of claim 17, wherein, The inlet manifold includes: The main manifold path extends vertically from the inlet of the heat exchanger; and Multiple manifold branches extend from the main manifold path to connect to the multiple heat exchange paths.
19. The HVAC system according to claim 17, wherein, The plurality of capillaries are connected to the heat exchanger outlet via one of the nozzles or venturi tubes.
20. The HVAC system according to claim 17, wherein, The heat exchanger inlet and the heat exchanger outlet are located at the same end of the heat exchanger.