Patent Publication Number: US-2023138320-A1

Title: Refrigerant cooled heat sink for power electronic modules

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 63/274,729, filed Nov. 2, 2021, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Exemplary embodiments pertain to the art of heat exchangers, and more particularly, the present disclosure relates to an interface for cooling power electronics that are mounted to a heat exchanger. 
     Power electronic devices such as motor drives can generate waste heat during operation based on the efficiency of the device. Additionally, when the power electronic devices heat up, their efficiency can degrade adding to the amount of heat they generate. When configured into a refrigeration system, effective thermal integration of these devices can be important aspect to the system&#39;s overall efficiency and reliability. Consequently, a goal of the system integrator is to maintain these components within a range of operating temperatures which will maximize the system efficiency. Accordingly, there remains a need in the art for heat exchangers configured to closely integrate with power electronic devices which can maintain optimal temperatures for these components under a variety of load conditions. 
     BRIEF DESCRIPTION 
     According to an embodiment, a heat exchanger assembly includes a housing having at least one area of heat flux and a fluid circuit arranged within an interior of the housing. The fluid circuit having an inlet manifold, an outlet manifold, and at least one fluid passage connecting the inlet manifold and the outlet manifold. The at least one fluid passage is positioned relative to the housing to perform localized cooling of the housing at the at least one area of heat flux. A cooling medium circulates through the fluid circuit. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments comprising at least one power electronics module mounted to the housing, the at least one area of heat flux being formed at the at least one power electronics module. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one power electronics module is mounted in a vertical plane. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one fluid passage is axially aligned with the at least one power electronics module relative to the housing. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one power electronics module is in an overlapping relationship with the at least one fluid passage. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments at least one of a size and shape of the at least one fluid passage is complementary to the at least one power electronics module. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one fluid passage includes a single channel. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one fluid passage includes a plurality of channels, the plurality of channels being arranged in parallel. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the plurality of channels are formed as a plurality of recesses in the housing. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one fluid passage comprises: a single recess formed in the housing; and a divider arranged within the single recess, the divider forming the plurality of channels within the single recess. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the plurality of channels are coupled to the inlet manifold via an inlet interface and the plurality of channels are coupled to the outlet manifold via an outlet interface. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one power electronics module includes a plurality of power electronics modules and the at least one area of heat flux includes a plurality of areas of heat flux, each of the plurality of areas of heat flux being formed at a respective power electronic module of the plurality of power electronics modules. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the at least one fluid passage further comprises a plurality of fluid passages and the inlet manifold is configured such that the cooling medium is equally distributed to each of the plurality of fluid passages. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments a hydraulic diameter of the inlet manifold varies over a length of the inlet manifold. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments comprising a distributor arranged within the inlet manifold. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the plurality of fluid passages is connected to the inlet manifold via a plurality of inlet interfaces, and a hydraulic diameter of a connection between each of the plurality of inlet interfaces and the inlet manifold varies over a length of the inlet manifold. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments a pressure drop across the plurality of fluid passages is at least five times greater than a pressure drop within the inlet manifold. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the fluid circuit further comprises a fluid inlet operably coupled to the inlet manifold and a fluid outlet operably coupled to the outlet manifold, the fluid inlet being disposed below the fluid outlet such that during operation a flow direction of the cooling medium through the inlet manifold and the outlet manifold opposes gravity. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the housing further comprises a first housing portion and a second housing portion joined along corresponding mating surfaces. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments at least one of the first housing portion and the second housing portion is a plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    is a schematic illustration of an exemplary heat exchanger and power electronic modules mounted thereto according to embodiment; 
         FIG.  2    is a front view of an exemplary heat exchanger having a plurality of power electronic mounted thereto according to an embodiment; and 
         FIG.  3    is a perspective view of the cross section A-A of the heat exchanger of  FIG.  2    according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     With reference now to  FIG.  1   , a schematic illustration of an example of a heat exchanger  20  is illustrated according to an embodiment. As shown, the heat exchanger  20  includes a housing  22  formed from a heat conductive material, such as a metal material. For example, the housing  22  may be formed from any suitable metal, e.g., aluminum, aluminum alloy, copper, copper alloy, or the like. In the illustrated, non-limiting embodiment, the housing  22  is formed from a plurality of housing portions, such as a first housing portion  24 , and a second housing portion  26 , joined along corresponding mating surfaces to form a seam  28  therebetween. In such embodiments, the first and second housing portions  24 ,  26  can abut one another along a side and can be joined using any suitable means such as brazing, welding, clamping, compressing, bolting, and the like. Although two housing portions  24 ,  26  are illustrated in the exemplary embodiments, it should be understood that a housing  22  formed from any number of housing portions including a single housing portion, or more than two housing portions for example, are within the scope of the disclosure. 
     The mating surfaces of the first and second housing portions  24 ,  26  may be configured to correspond to one another, e.g., to fit together to seal a fluid circuit therebetween (the fluid circuit to be described in more detail below). In an embodiment, the mating surfaces of the first and second housing portions  24 ,  26  include precision surfaces formed from a process having highly accurate and precise dimensional control, such as through computer numerical control (CNC) machining process and/or net shape, or near net shape manufacturing process. Optionally a sealing material can be disposed between the first and second housing portions  24 ,  26  to aide in preventing leakage from the fluid circuit. 
     As shown in  FIG.  1   , the first and second housing portions  24 ,  26  can have different thicknesses, measured along the z-axis. In the illustrated, non-limiting embodiment, a thickness of the first housing portion  24  is greater than a thickness of the second housing portion. However, embodiments where the first housing portion  24  and the second housing portion  26  are equal in thickness, or alternatively, where a thickness of the second housing portion  26  is greater than a thickness of the first housing portion  24  are also within the scope of the disclosure. In an embodiment, each of the first housing portion  24  and the second housing portion  26  is formed as a substantially solid plate. However, embodiments where one or more of the housing portions  24 ,  26  has another configuration are also contemplated herein. 
     With continued reference to  FIG.  1   , and further reference to  FIG.  2   , a heat exchanger  20  as described herein can be used, such as in a vapor compression system for example, to cool at least one power electronic module  30 . As described herein, a heat exchanger  20  having one or more power electronics modules  30  mounted thereon may be considered a heat exchanger assembly. The term “power electronic module” as used herein can refer to any electronic component which can provide a controlled output power by modulating and/or converting a supplied input power (e.g., a variable frequency drive, power rectifier, power converter, and the like). Such a power electronic module  30  can be used to control the speed of a compressor and/or the speed of the fan of a vapor compression system (e.g., chiller) based on various predetermined system conditions. 
     In an embodiment, the at least one power electronic module  30  is mounted directly to a surface  32  of at least one of the plurality of housing portions, such as first housing portion  24  for example. In the illustrated, non-limiting embodiment, a plurality of power electronics modules  30  are mounted to a vertically oriented surface  32  (e.g., vertical plane) of the housing  22 . However, embodiments where one or more power electronics modules  30  are mounted to a surface of a housing  22  having a non-vertical orientation, such as a horizontal surface for example, are also within the scope of the disclosure. The power electronic modules  30  may be mounted to the housing  22  of the heat exchanger  20  via one or more fasteners in such a way that facilitates the transfer of thermal energy away from the power electronics module  30 . 
     The one or more power electronics modules  30  may include a printed circuit board  34  on which various other electrical components (not shown) are mounted (e.g., protection, signal processing, and filtering related components). The reliability and life of the one or more power electronic modules  30  can depend upon precluding such electrical components from operating at high temperatures and/or precluding their exposure to thermal shock. Because the internal components of the power electronics module can generate a large amount of heat, each of the power electronics modules  30  has a heat sink interface (not shown) which is designed for attachment to a heat sink, such as the heat exchanger  20 . When the power electronics modules  30  are secured in thermal communication with the heat exchanger  20 , the heat generated by the power electronics module  30  is at least partially removed through the heat sink interface to keep the power electronics module  30  cooled below its maximum allowable operating temperature (e.g., 150° C.). 
     With continued reference to  FIGS.  1  and  2   , and further reference to  FIG.  3   , the heat exchanger  20  includes a fluid circuit  40  formed between the first and second housing portions  24 ,  26 . The fluid circuit  40  includes a fluid inlet  42  and fluid outlet  44  formed in the housing  22 . In an embodiment, the fluid inlet  42  is disposed vertically below the fluid outlet  44  such that during operation of the heat exchanger  20 , a flow direction of a cooling medium, such as refrigerant for example, through the fluid circuit opposes gravity. The fluid inlet  42  and the fluid outlet  44  can be any shape, such as in the depth dimension (e.g., in the z-x plane of the attached figure), including the shape of a circle, oval, triangular, square, rectangular, or any simple polygonal shape or portion thereof. Also, the fluid outlet  44  can have much larger diameter compared to the fluid inlet  42 , thereby helping to reduce the pressure drop for the cooling medium mixture comprised of gas and liquid passing through the fluid outlet  44 . Further, the perimeter of one or both of the fluid inlet  42  and the fluid outlet  44  can be formed by a recess in at least one or both of the housing portions  24 ,  26 . The recess may extend to an edge of a respective housing portion, may be arranged centrally relative to a housing portion, or may overlap with the seam  28  defined between two adjacent housing portions  24 ,  26 . 
     An example of the fluid circuit  40  is best illustrated in the cross-sectional view of the heat exchanger  20  shown in  FIG.  3   . In addition to the fluid inlet  42  and the fluid outlet  44 , the fluid circuit includes a first or inlet manifold  46 , a second or outlet manifold  48 , and at least one fluid passage  50  connecting the first and second manifolds  46 ,  48 . In an embodiment, the at least one fluid passage  50  includes a plurality of fluid passages  50 . The fluid inlet  42  can be configured to connect a first cooling medium (e.g., refrigerant) source, such as a condenser of a vapor compression system for example, to the inlet manifold  46  using any suitable mechanical connection. Similarly, the fluid outlet  44  can be configured to connect a first heat transfer fluid sink, such as an evaporator of a vapor compression system for example, to the outlet manifold  48  using any suitable mechanical connection (e.g., compression coupling, brazing, welding, and the like). 
     One or more of the inlet manifold  46 , the outlet manifold  48 , and the at least one fluid passage  50  is formed as a recess in at least one of the first housing portion  24  and the second housing portion  26 . In an embodiment, the inlet manifold  46 , the outlet manifold  48 , and the plurality of fluid passages  50  are formed as a plurality of connected recesses in at least one housing portion, such as the second housing portion  26  for example. Accordingly, the plurality of recesses form the fluid circuit  40  disposed between the first and second housing portions  24 ,  26  when the housing portions  24 ,  26  are joined. For example, a first housing portion  24  having a plurality of connected recesses can be joined to a flat, second housing portion  26  that does not have any recesses formed therein. In another embodiment, a first housing portion  24  and a second housing portion  26  can each have a plurality of connected recesses which mirror one another such that when the first and second housing portions  24 ,  26  are joined, the connected recesses form the fluid circuit. The plurality of connected recesses can have any shape in the depth dimension (e.g., as projected onto a z-y plane of the attached figures, into the plate), including semi-circular, semi-oval, triangular, square, rectangular, or any simple polygonal shape or portion thereof. 
     The mating surfaces of the first and second housing portions  24 ,  26  can substantially border the plurality of connected recesses. Optionally, the mating surfaces can include raised or recessed portions, or other engagement features to aid in alignment of the housing portions  24 ,  26  prior to joining. 
     The inlet manifold  46  and the outlet manifold  48  are oriented at a non-zero angle relative to the fluid inlet  42  and the fluid outlet  44 , respectively. In the illustrated, non-limiting embodiment, the inlet manifold  46  and the outlet manifold  48  are oriented substantially horizontally. Although the inlet manifold  46  and the outlet manifold are illustrated as being arranged generally perpendicular to the fluid inlet  42  and fluid outlet  44 , embodiments where the inlet manifold  46  and the outlet manifold  48  are arranged at another non-parallel configuration are also within the scope of the disclosure. Further, the one or more fluid passages connecting the inlet manifold  46  and the outlet manifold  48  may extend substantially perpendicular to the inlet and outlet manifolds  46 ,  48 , such as in a vertical orientation as shown in  FIG.  3   , or alternatively, may be arranged at a non-zero angle relative to the direction of gravity. 
     In an embodiment, one or more fluid passages  50  of the fluid circuit  40  are configured to perform localized cooling at the areas of the heat exchanger  20  with the greatest heat flux, such as the areas where the power electronics modules are located (in contrast with cooling the entire heat exchanger  20 ). These one or more areas of the greatest heat flux may be referred to herein generally as at least one “area of heat flux.” Accordingly, the at least one fluid passage  50  of the fluid circuit  40  is associated with a power electronics module  30  and in embodiments of the heat exchanger assembly having a plurality of power electronics modules  30 , the fluid circuit  40  has a plurality of fluid passages  50 , each fluid passage  50  being associated with a respective power electronics module  30 . Each fluid passage  50  may be configured to remove heat from a specific power electronics module  30 . In an embodiment, the at least one fluid passage  50  associated with a respective power electronics module  30  is physically located within the heat exchanger  20  in alignment with the power electronics module  30 . For example, the at least one fluid passage  50  may be axially aligned with a respective power electronics module  30  relative to a major axis of the heat exchanger  20 , such as the X axis ( FIG.  1   ) for example. Accordingly, the power electronics module  30  is mounted in an overlapping relationship with a corresponding fluid passage  50 . In such embodiments, the fluid circuit  40  may, but need not include a fluid passage  50  at an axial location of the heat exchanger  20  disposed between adjacent power electronic modules  30 . 
     In an embodiment, a fluid passage  50  connecting the inlet manifold  46  and the outlet manifold  48  of the fluid circuit  40  includes a single channel  52  through which a cooling medium, such as refrigerant may flow. In other embodiments, at least one fluid passage  50  includes a plurality of channels  52  arranged in parallel. In embodiments where a fluid passage  50  includes a plurality of channels  52 , the channels  52  may have similar, or alternatively, varying configurations. Because each fluid passage  50  is associated with the cooling of a respective power electronics module  30  mounted to the heat exchanger  20 , it should be understood that in embodiments where the fluid circuit  40  includes a plurality of fluid passages  50 , the configuration of each of the plurality of fluid passages  50  may be identical, or alternatively may vary, such as based on the size and cooling required by a corresponding power electronics module  30 . 
     In embodiments where a fluid passage  50  includes a plurality of channels, the plurality of channels  52  may connect to the inlet manifold  46  via a single inlet interface and/or may connect to the outlet manifold  48  via a single outlet interface, as shown in  FIG.  3   . However, in an embodiment, at least one of the plurality of channels  52  may fluidly couple to one or both of the inlet manifold  46  and the outlet manifold at a separate location from the other channels  52  of the fluid passage  50 . 
     The plurality of channels  52  that form a fluid passage  50  may be defined by a plurality of separate recesses formed into one or more portions of the housing  22 . In another embodiment, the fluid passage  50  may be defined by a single recess formed in one or more portions of the housing  22  and a divider  54  or other component configured to fluidly separate the recess into a plurality of distinct channels  52  may be installed within the recess. In such embodiments, one or more dimensions, such as a measured along the X-axis or the Y-axis for example, may match a corresponding dimension of the power electronics module  30  at that location. 
     Further, in an embodiment, the inlet manifold  46  and the inlets to each of the fluid passages are configured such that the cooling medium is equally distributed between each of the plurality of fluid passages  50 , and in some embodiments to each of the plurality of channels  52  within a fluid passage  50 . To achieve this uniform distribution from the inlet manifold  46  to the plurality of fluid passages  50 , the hydraulic diameter of the inlet manifold  46  may vary over the axial length of the inlet manifold. In another embodiment, an insert, such as a distributor type of device may be arranged within the inlet manifold. 
     Alternatively, or in addition to the above embodiments, the hydraulic diameter of the connection between the inlet manifold  46  and the inlet interface of each of the plurality of fluid passages  50  may vary based on the position of the fluid passage relative to axis of the inlet manifold  46 . For example, the hydraulic diameter may be greatest at the inlet interface at the centermost fluid passage  50 , or alternatively, at the two centrally located fluid passages  50  (in embodiments having an even number of power electronics modules  30  and therefore fluid passages  50 ). Further, the hydraulic diameter of the inlet end of the outermost fluid passages  50  may be about 0.25 or 0.3 of the maximum hydraulic diameter of the inlet end of the central fluid passage  50 , and for each fluid passage  50  disposed between an outermost fluid passage  50  and the central fluid passage  50 , the hydraulic diameter of the inlet end will gradually increase towards the central fluid passage  50 . 
     Furthermore, the configuration of the fluid passages  50  may be substantially symmetrical relative to a central fluid passage  50  or a plane defined between two central fluid passages  50 . For example, in embodiments having six fluid passages as shown, the ratio of the hydraulic diameter to the maximum hydraulic diameter at the inlets associated with the two outermost fluid passages is about 0.3, the ratio at the two centrally located fluid passages is 1 and the ratio at the fluid passages  50  between each outermost and each central fluid passage  50  is about 0.6. However, it should be understood that any suitable ratios are within the scope of the disclosure. 
     For efficient and balanced distribution of the cooling medium, the pressure drop across channels the inlet manifold  46  and the outlet manifold  48  shall be significantly lower, such as two to five times lower than the pressure drop across the fluid passages  50 . In an embodiment, the configuration of the inlet manifold  46  and/or the plurality of inlet interfaces between the fluid passages  50  and the inlet manifold  46  is selected such that the pressure drop within the inlet manifold  46  is significantly smaller than the pressure drop across the fluid passages  50 . In an embodiment, the pressure drop across the fluid passages  50  is at least five times, and in some embodiments between about five to about ten times greater than the pressure drop of the cooling medium as it passes through the inlet manifold  46 . In such embodiments, the hydraulic diameter of the inlet end and outlet end of the fluid passage is less than a central portion of the fluid passage  50 . 
     A heat exchanger having a fluid circuit  40  designed to perform balanced and localized cooling at the areas of the heat exchanger  20  that have the greatest heat flux will maximize the heat transfer from the power electronics modules  30  to the cooling medium, thereby avoiding hot pockets and extending the life of the electronic components within the power electronics modules  30 . 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.