WO2021016467A1

WO2021016467A1 - A flooded evapoarator and an air conditioner having a flooded evapoarator

Info

Publication number: WO2021016467A1
Application number: PCT/US2020/043299
Authority: WO
Inventors: Fang XUE; David Andrew BRADSHAW; Xiuping Su; Lu MEI; Kun Lin
Original assignee: Johnson Controls Technology Company; Johnson Controls Air Conditioning And Refrigeration (Wuxi) Co., Ltd
Priority date: 2019-07-23
Filing date: 2020-07-23
Publication date: 2021-01-28

Abstract

A flooded evaporator (38) for a HVAC&R system (10) includes a shell (102) defining an interior volume (264) and a refrigerant inlet (110) configured to direct a two-phase refrigerant (106) into the shell (102). The flooded evaporator (68) includes a liquid distributor (104) disposed within the interior volume (264) of the shell (102) and configured to receive the two-phase refrigerant (106) from the refrigerant inlet (110). The liquid distributor (104) includes a main body (160, 162) coupled to a bottom portion (114) of the shell and separating the interior volume (264) of the shell into a distributor volume (222) and a remaining volume (262). The liquid distributor (104) also includes a refrigerant passage (352) formed in the main body (160, 162) and fluidly coupling the distributor volume (222) and the remaining volume (262). The refrigerant passage (352) includes a first portion and second portion, the first portion includes a first cross-sectional area greater than a second cross-sectional area of the second portion, and the first portion is closer to the refrigerant inlet (110) than the second portion.

Description

A FLOODED EVAPOARATOR AND AN AIR CONDITIONER HAVING A FLOODED

EVAPOARATOR

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from and the benefit of U.S. Provisional Application Serial No. 62/877,637, entitled“SYSTEMS FOR LOW PRESSURE LIQUID DISTRIBUTORS,” filed July 23, 2019, which is herein incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] Vapor compression systems are utilized in residential, commercial, and industrial environments to control environmental properties, such as temperature and humidity, for occupants of the respective environments. The vapor compression system circulates a working fluid, typically referred to as a refrigerant, which changes phases between vapor, liquid, and combinations thereof in response to being subjected to different temperatures and pressures associated with operation of the vapor compression system. Certain vapor compression systems include a flooded evaporator having a liquid distributor for distributing a refrigerant to a bottom portion of a shell of the flooded evaporator. The flooded evaporator enables a fluid flowing through a tube bundle within the shell to exchange thermal energy with and evaporate a resulting pool of the refrigerant into a refrigerant vapor. Unfortunately, the flooded evaporator may not be designed to efficiently distribute flows of certain types of refrigerant, thus limiting the operating efficiency and capacity of the flooded evaporator utilizing certain types of refrigerant.

[0003] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. SUMMARY

[0004] In one embodiment of the present disclosure, a flooded evaporator for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a shell defining an interior volume and a refrigerant inlet configured to direct a two-phase refrigerant into the shell. The flooded evaporator also includes a liquid distributor disposed within the interior volume of the shell and configured to receive the two-phase refrigerant from the refrigerant inlet. The liquid distributor includes a main body coupled to a bottom portion of the shell and separating the interior volume of the shell into a distributor volume and a remaining volume. The liquid distributor also includes a refrigerant passage formed in the main body and fluidly coupling the distributor volume and the remaining volume. The refrigerant passage includes a first portion and second portion, the first portion includes a first cross-sectional area greater than a second cross-sectional area of the second portion, and the first portion is closer to the refrigerant inlet than the second portion.

[0005] In another embodiment of the present disclosure, a flooded evaporator of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a shell defining an interior volume and a refrigerant inlet formed in the shell and configured to direct a two-phase refrigerant into the shell. The flooded evaporator includes a liquid distributor disposed within the interior volume of the shell and configured to receive the two-phase refrigerant from the refrigerant inlet. The liquid distributor includes a main body having at least one panel coupled to a bottom portion of the shell and separating the interior volume of the shell into a distributor volume and a remaining volume. The at least one panel includes a first edge and a second edge. The liquid distributor also includes a slot arrangement formed in the first edge and the second edge of the at least one panel. The slot arrangement defines a refrigerant passage that fluidly couples the distributor volume and the remaining volume, and an open cross-sectional area of the slot arrangement decreases along a longitudinal axis extending from the refrigerant inlet.

[0006] In a further embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a flooded evaporator configured to evaporate a two-phase refrigerant into a refrigerant vapor. The flooded evaporator includes a shell defining an interior volume, and the shell includes a first longitudinal end portion and a second longitudinal end portion. The flooded evaporator includes a refrigerant inlet configured to direct the two-phase refrigerant into the shell at a longitudinal position between the first longitudinal end portion and the second longitudinal end portion. Additionally, the flooded evaporator includes a liquid distributor disposed within the interior volume of the shell. The liquid distributor includes a main body coupled to a bottom portion of the shell, and the main body extends from the first longitudinal end portion of the shell to the second longitudinal end portion of the shell. The main body defines a distributor volume configured to receive the two-phase refrigerant from the refrigerant inlet. The liquid distributor also includes a slot arrangement formed in the main body and configured to direct the two-phase refrigerant out of the distributor volume. The slot arrangement includes a varied open cross-sectional area that is greater proximate the refrigerant inlet than near the first longitudinal end portion and the second longitudinal end portion.

[0007] Other features and advantages of the present application will be apparent from the following, more detailed description of the embodiments, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the application.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. l is a perspective view of an embodiment of a building that may utilize a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0009] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0010] FIG. 3 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure; [0011] FIG. 4 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0012] FIG. 5 is a cross-sectional axial view of an embodiment of an evaporator having a rectangular-shaped refrigerant distributor, in accordance with an aspect of the present disclosure;

[0013] FIG. 6 is a cross-sectional axial view of an embodiment of an evaporator having a triangle-shaped refrigerant distributor, in accordance with an aspect of the present disclosure;

[0014] FIG. 7 is a cross-sectional axial view of an embodiment of an evaporator having a ladder-shaped refrigerant distributor, in accordance with an aspect of the present disclosure;

[0015] FIG. 8 is a schematic diagram of an embodiment of a computational fluid dynamics (CFD) screen overlay of a portion of the refrigerant distributor of FIG. 6 in operation, in accordance with an aspect of the present disclosure;

[0016] FIG. 9 is a bar graph of an embodiment of CFD analysis results, which illustrate mass flowthrough slots of the refrigerant distributor of FIG. 8, in accordance with an aspect of the present disclosure;

[0017] FIG. 10 is a two-dimensional graph of a static pressure distribution within an embodiment of a refrigerant distributor, in accordance with an aspect of the present disclosure;

[0018] FIG. 11 is a cross-sectional side view of an embodiment of a refrigerant distributor having a parabolic slot layout, in accordance with an aspect of the present disclosure;

[0019] FIG. 12 is a cross-sectional side view of an embodiment of a refrigerant distributor having a height-variable slot layout, in accordance with an aspect of the present disclosure; [0020] FIG. 13 is a cross-sectional side view of an embodiment of a refrigerant distributor having a width-variable slot layout, in accordance with an aspect of the present disclosure; and

[0021] FIG. 14 is a cross-sectional side view of an embodiment of a refrigerant distributor having a density-variable slot layout.

DETAILED DESCRIPTION

[0022] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0023] Embodiments of the present disclosure are directed toward heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, including systems for liquid distributor (e.g., fluid distributor) construction and operation within flooded evaporators of HVAC&R systems. Although referred to herein as a liquid distributor, it should be understood that the distributor disclosed herein may generally be a fluid or refrigerant distributor configured to direct a flow of refrigerant, such as a flow of two-phase refrigerant, into the flooded evaporator. Generally, HVAC&R systems include a closed refrigeration circuit having an evaporator configured to evaporate, or heat, a refrigerant therein to enable the HVAC&R system to condition an interior space. Certain HVAC&R systems utilize a flooded operating configuration for the evaporator by maintaining a pool or volume of refrigerant within a shell of the flooded evaporator. By utilizing a flooded evaporator with an optimized or improved liquid distributor, the HVAC&R system may operate with a low pressure refrigerant but without a significant resulting pressure drop in order to enhance evaporator performance compared to traditional evaporators. Moreover, the HVAC&R system of certain embodiments may alternatively direct medium or high pressure refrigerant within the flooded evaporator, thereby providing improved refrigerant control that increases the operating efficiency of the flooded evaporator compared to the traditional evaporators that lack the presently disclosed liquid distributor.

[0024] For example, as discussed in more detail below, liquid distributors disclosed herein include an arrangement and sizing of slots, or a slot layout, that may be particularly suited for distributing low pressure refrigerant within a flooded evaporator. According to computational fluid dynamics (CFD) analysis, the low pressure refrigerant flows at a relatively high velocity near the refrigerant inlet. This high velocity may limit an amount of the low pressure refrigerant that may exit the liquid distributor through slots near the refrigerant inlet. As such, present techniques include a slot layout that generally includes slots defined within the liquid distributor that decrease in open area (e.g., cross-sectional area) along a direction extending from a refrigerant inlet toward a longitudinal end of the liquid distributor. That is, slots that are near the refrigerant inlet may have a greater width and/or height than slots that are further from the refrigerant inlet. Additionally, there may be a greater number of slots near the refrigerant inlet and a lesser number of slots further from the refrigerant inlet. In other embodiments, the slot layout includes a single slot on each lateral side of the liquid distributor that reduces in height as the slot approaches the longitudinal end of the liquid distributor. The slot layout therefore produces an even distribution of the low pressure refrigerant that reduces or minimizes pressure drop, thereby improving heat transfer performance and overall performance of HVAC&R systems.

[0025] Turning now to the drawings, FIG. l is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial setting. The HVAC&R system 10 may include a vapor compression system 14 that supplies a chilled liquid, which may be used to cool the building 12. The HVAC&R system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12. The air distribution system can also include an air return duct 18, an air supply duct 20, and/or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC&R system 10. The HVAC&R system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC&R system 10 may include air handlers 22 and/or other components that may be shared between or among floors.

[0026] FIGS. 2 and 3 are embodiments of the vapor compression system 14 that can be used in the HVAC&R system 10. The vapor compression system 14 may circulate a refrigerant through a circuit starting with a compressor 32. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. The vapor compression system 14 may further include a control panel 40 that has an analog to digital (A/D) converter 42, a microprocessor 44, a non-volatile memory 46, and/or an interface board 48.

[0027] Some examples of fluids that may be used as refrigerants in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants, for example, R- 410A, R-407, R-134a, hydrofluoro olefin (HFO),“natural” refrigerants like ammonia (MR), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based refrigerants, water vapor, or any other suitable refrigerant. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, also referred to as low pressure refrigerants, versus a medium pressure refrigerant, such as R-134a. As used herein,“normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.

[0028] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and/or the evaporator 38. The motor 50 may drive the compressor 32 and may be powered by a variable speed drive (VSD) 52. The VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0029] The compressor 32 compresses a refrigerant vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The refrigerant vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The liquid refrigerant from the condenser 34 may flow through the expansion device 36 to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser.

[0030] The liquid refrigerant delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34. The liquid refrigerant in the evaporator 38 may undergo a phase change from the liquid refrigerant to a refrigerant vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62. The cooling fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via thermal heat transfer with the refrigerant. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any case, the vapor refrigerant exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle. [0031] FIG. 4 is a schematic of the vapor compression system 14 with an intermediate circuit 64 incorporated between condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a "surface economizer." In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the liquid refrigerant received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. Additionally, the intermediate vessel 70 may provide for further expansion of the liquid refrigerant because of a pressure drop experienced by the liquid refrigerant when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate vessel may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the liquid refrigerant exiting the condenser 34 because of the expansion in the expansion device 66 and/or the intermediate vessel 70. The liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38.

[0032] Keeping the above understanding of the HVAC&R system 10 in mind, FIG. 5 is a cross-sectional axial view of the evaporator 38 (e.g., flooded evaporator) having a shell 102 with a liquid distributor 104 (e.g., distributor, two-phase distributor, refrigerant distributor, fluid distributor, etc.) disposed therein. The liquid distributor 104 receives a refrigerant 106 (e.g., R1233zd, a two-phase refrigerant, a liquid-vapor refrigerant, etc.) from a refrigerant inlet 110 and distributes the refrigerant 106 within a refrigerant pool 112 in a bottom portion 114 of the shell 102. The evaporator 38 may also include a cooling fluid inlet and a cooling fluid outlet, which respectively couple one or multiple tube bundles 124 within the evaporator 38 to the supply line 60S and the return line 60R (e.g., connected to the cooling load 62). At least one tube bundle 124, which has heat exchange tubes 126 therein, may be submerged in the refrigerant pool 112 to enable conduction between the refrigerant 106 (e.g., two-phase refrigerant) and cooling fluid flowing within the tube bundle 124. Accordingly, as discussed above, the evaporator 38 reduces a temperature of the cooling fluid in the tube bundles 124 via heat transfer to the refrigerant 106, which evaporates into a refrigerant vapor 130. Under certain conditions, the resulting refrigerant vapor 130 may entrain or“carryover” liquid from the refrigerant pool 112, which if not removed, may induce wear on impellers of the compressor 32 or other components of the HVAC&R system 10. Thus, to reduce or eliminate carryover of liquid refrigerant from the evaporator 38, the evaporator 38 may include a mesh eliminator 132 disposed above the tube bundles 124. The refrigerant vapor 130 may thus exit the evaporator 38 via a suitable refrigerant outlet, which is fluidly coupled to the compressor 32.

[0033] Notably, as discussed in more detail below, the liquid distributor 104 includes a specific sizing and arrangement of one or more slots (e.g., distribution devices), hereinafter collectively referred to as a slot layout, which enhances the dispersal of the refrigerant 106 into the refrigerant pool 112. The particular slot layout therefore enables the evaporator 38 to operate with a reduced pressure drop, which may otherwise limit the operating efficiency of flooded evaporators utilizing low pressure refrigerant or prevent operation with low pressure refrigerant altogether. However, it should be understood that the liquid distributor 104 may also be utilized with medium or high pressure refrigerants, such as R- 134a, to facilitate the particular direction of the refrigerant 106 to desired or targeted regions of the evaporator 38 for enhanced operating efficiency. In some embodiments, the slot layout is determined via computational fluid dynamics (CFD) to more evenly or proportionally distribute the refrigerant 106 along a longitudinal length of the liquid distributor 104, as discussed below.

[0034] Additionally, the slot layout discussed in more detail below may be incorporated into embodiments of the liquid distributor 104 having any suitable shape. For example, in the embodiment illustrated in FIG. 5, the liquid distributor 104 has a rectangular-shaped cross-section in which a top panel 140 of the liquid distributor 104 is substantially parallel (e.g., within 5 percent of parallel) with a horizontal axis 142 of the evaporator 38. Slots may therefore be formed in vertical panels 144 of the liquid distributor 104 that extend along a vertical axis 146 of the evaporator 38 from the top panel 140 toward the bottom portion 114 of the shell 102.

[0035] Moreover, FIG. 6 is a cross-sectional axial view of the evaporator 38 illustrating an embodiment of the liquid distributor 104 having a triangular or sector shaped cross- section formed by a first side panel 160 and a second side panel 162, each in contact with the bottom portion 114 of the shell 102. Further, FIG. 7 is a cross-sectional axial view of the evaporator 38 illustrating an embodiment of the liquid distributor 104 having a plateau or ladder shape formed by two side panels 180 and a top panel 182 disposed therebetween. By extending along a shorter arc of the shell 102, the liquid distributors 104 of FIGS. 6 and 7 may enable more heat exchange tubes 126 to be included in the tube bundles 124 of the respective evaporator 38 compared to rectangular-shaped embodiments of the liquid distributor 104. For example, as shown by the horizontal dashed lines 184 overlaid in a same vertical position on each of FIGS. 5-7, the same quantity of heat exchange tubes 126 may be disposed within the shell 102 of embodiments illustrated in FIGS. 6 and 7 without extending as far upward along a height 186 of the evaporator 38 as heat exchange tubes 126 disposed within the shell 102 of the embodiment illustrated in FIG. 5. However, it should be understood that each of the liquid distributors 104 of FIGS. 5-7 may be formed with the slot layout disclosed herein to improve refrigerant distribution. Moreover, the liquid distributors 104 of each of FIGS. 5-7 may be formed by joining (e.g., welding) the corresponding panels together along a length of the liquid distributor 104, in some embodiments. In other embodiments, the liquid distributors 104 may be formed by bending an appropriately-sized plate or panel into the target rectangular, triangular, or ladder shape, thereby reducing a complexity of the construction process for the liquid distributors 104.

[0036] To provide better understanding of the reduced pressure drop provided by the slot layout of present embodiments, FIG. 8 is a schematic diagram of a CFD screen overlay 200 of the liquid distributor 104 of FIG. 6 in operation. In particular, the CFD screen overlay 200 may be displayed on an electronic display of any suitable computing device (e.g., laptop computer, desktop computer, tablet) having a processor and memory therein, such as computing device 202 illustrated in FIG. 8. The present embodiment of the CFD screen overlay 200 is a computation and illustration of fluid flow within and traveling out of the liquid distributor 104 of FIG. 6. Although presently illustrated for a portion of a lower quadrant of the evaporator 38 discussed above, it should be understood that a CFD computation may also be performed and illustrated with respect to a full lower half or an entire body or volume of the evaporator 38, according to the present techniques.

[0037] The liquid distributor 104 includes the triangular cross-section or sector shape in the present embodiment, which is formed by the first side panel 160 disposed at an angle 206 relative to the second side panel 162. However, it should be understood that any other suitably-shaped liquid distributor may be employed within the evaporator 38, as discussed above. The first side panel 160 and the second side panel 162 may be referred to as the main body of the liquid distributor 104. As illustrated, a first lower edge 210 of the first side panel 160 and a second lower edge 212 of the second side panel 162, which may be referred to as longitudinally-extending edge portions, are each in contact with the bottom portion 114 of the shell 102. A distal panel 214 couples the first side panel 160 and the second side panel 162 at a longitudinal end 216 of the liquid distributor 104 near a wall panel 220 (e.g., tubesheet, shell end) of the evaporator 38, thus forming a distributor volume 222 within the liquid distributor 104. Moreover, the liquid distributor 104 includes a slot layout 230 in which a quantity of slots 232 is formed along the lower edges 210, 212 of the side panels 160, 162. The slots 232 may be cut into or formed within sheet metal or other material from which the liquid distributor 104 is formed. In some embodiments, the side panels 160, 162 are separate pieces that are welded or otherwise coupled together to form a joint along a longitudinally-extending centerline 234 of the liquid distributor 104. In other embodiments, the liquid distributor 104 is constructed from a single panel having a longitudinally-extending bend or crease formed along the longitudinally-extending centerline 234, as mentioned above. As noted herein, a refrigerant passage is defined as the open cross-sectional area between the slots 232 and the bottom portion 114 of the shell 102 for the refrigerant 106 (e.g., two-phase refrigerant) to traverse. [0038] Notably, the slots 232 decrease in width along a direction 240 extending from the refrigerant inlet 110 to the wall panel 220 of the shell 102. In other words, a proximal slot 242 that is nearest the refrigerant inlet 110 has a slot width 244 that is greater than a slot width 246 of a distal slot 248 that is nearest the wall panel 220. The quantity and/or size of the slots 232 of the liquid distributor 104 may be greater than the slots of traditional distributors utilized with medium or high pressure refrigerants, in some embodiments. Compared to these traditional distributors, the increased quantity and/or sizing of slots 232 corresponds to an increased total slot area for distribution of the refrigerant 106. In the present embodiment, the liquid distributor 104 includes 20 slots 232 (e.g., 10 slots 232 on each lateral side relative to a longitudinal axis 250 of the evaporator 38), though it should be understood that 12, 14, 16, 18, or another suitable number of slots 232 may be utilized.

[0039] Via the various embodiments of the slot layout 230 discussed herein, the liquid distributor 104 is configured to efficiently direct the refrigerant 106 (e.g., two-phase refrigerant) from the refrigerant inlet 110 and into the refrigerant pool 112. In particular, the CFD screen overlay 200 illustrates flow paths 260 of the refrigerant 106 traversing the slots 232 of the liquid distributor 104. That is, the refrigerant 106 is directed from the refrigerant inlet 110, within the distributor volume 222 of the liquid distributor 104, through one of the slots 232 of the liquid distributor 104, and into a remaining volume 262 (e.g., a volume outside the volume defined by the liquid distributor 104) of an interior volume 264 of the shell 102. The refrigerant inlet 110 is positioned at a longitudinal midpoint 266 of the liquid distributor 104 (e.g., relative to a longitudinal length of the shell 102 defined along the longitudinal axis 250) in the illustrated embodiment, though it should be understood that in other embodiments, the refrigerant inlet 110 may alternatively be positioned at the longitudinal end 216 or other position along the liquid distributor 104. In such embodiments, the slot layout 230 may be adapted such that slots 232 positioned closer to the refrigerant inlet 110 have a greater open area or refrigerant flow path area than slots 232 positioned further from the refrigerant inlet 110. Moreover, it should be understood that, in some embodiments, each longitudinal end 216 of the liquid distributor 104 may have a respective embodiment of the slot layout 230 in which one longitudinal end 216 has a different sizing and/or arrangement of slots 232 than the other, opposite longitudinal end 216. [0040] For further appreciation, FIG. 9 is a bar graph 300 of an embodiment of CFD analysis results illustrating mass flow of the refrigerant 106 (e.g., two-phase refrigerant) through the slots 232 of the liquid distributor 104 of FIG. 8. In the present embodiment, the slot position of slots 232 are labeled along an x-axis 302 of the bar graph 300, including the slots 232 formed along the first side panel 160 followed by the slots 232 formed along the second side panel 162. The bar graph 300 also includes a y-axis 304 representing mass flow 306 through each of the slots 232. Via the CFD analysis, it is presently recognized that supplying the refrigerant 106 into the liquid distributor 104 generates higher mass flows of the refrigerant 106 out of the slots 232 that are further from the refrigerant inlet 110 than the slots 232 that are nearer the refrigerant inlet 110. Therefore, the slots 232 furthest from the refrigerant inlet 110 may be sized and arranged to have a smaller open area than the slots 232 nearest to the refrigerant inlet 110. In this way, a larger portion of the refrigerant 106 may be directed through the relatively-larger open area of the slots 232 near the refrigerant inlet 110, thus enhancing refrigerant distribution and reducing pressure drop. The sizes and arrangement of the slots 232 in the slot layout 230 disclosed herein may therefore be distinctive to slot size and arrangement of a distributor disposed in a flooded evaporator utilizing a high pressure or medium pressure refrigerant, in some embodiments, which may be more efficiently distributed through slots that provide a smaller open area or refrigerant flow path area when positioned nearest to the refrigerant inlet.

[0041] FIG. 10 is a two-dimensional graph 320 illustrating a static pressure distribution within an embodiment of the liquid distributor 104 disclosed herein. A position along the longitudinal axis 250 of the liquid distributor 104 is represented by an x-axis 324 of the two-dimensional graph 320, and static pressure 326 within the liquid distributor 104 is represented by a y-axis 328 of the two-dimensional graph 320. As may be understood, the static pressure 326 within the liquid distributor 104 varies along the longitudinal axis 250. For example, the static pressure 326 is lowest near the middle of the liquid distributor 104 due to a relatively large velocity of the refrigerant 106 near the refrigerant inlet 110. As such, the rapid flow causes a limited amount of the refrigerant 106 to exit through the slots 232 in this portion of the liquid distributor 104, thereby increasing a demand for greater open area of the slots 232 proximate the refrigerant inlet 110. As the distance along the longitudinal axis 250 from the refrigerant inlet 110 and toward either longitudinal end 216 of the liquid distributor 104 increases, the static pressure 326 increases and the velocity decreases. Under these conditions, a lesser amount of the refrigerant 106 may exit the slots 232 disposed adjacent the longitudinal ends 216, thereby decreasing a demand for the slots 232 having a relatively large open area.

[0042] With this understanding of static pressure in the liquid distributor 104, the present embodiments of the slot layout 230 efficiently normalize the static pressure 326 and the velocity of the refrigerant 106 (e.g., two-phase refrigerant) by forming slots 232 with larger open areas in portions of the liquid distributor 104 closest to the refrigerant inlet 110. These larger open areas thereby provide more opportunities or flow paths for the refrigerant 106 to exit the liquid distributor 104 and decrease in static pressure 326. That is, distribution of the static pressure 326 more evenly along the length of the liquid distributor 104 may generate more even distribution of the refrigerant 106 within the evaporator 38. In some embodiments, to reduce or limit pressure drop within the liquid distributor 104, the total open area through the slots 232, collectively, may be 0.100, 0.125, 0.150, 0.175, or 0.200 in²/refrigeration ton.

[0043] Based on the CFD analysis, the slots 232 and/or slot layout 230 may have multiple different physical configurations to efficiently distribute the refrigerant 106 along the length of the liquid distributor 104. The slot layout 230 generally includes a larger open area in a central portion of the liquid distributor 104 (e.g., proximate the refrigerant inlet 110) than adjacent the longitudinal ends 216 of the liquid distributor 104. Indeed, this arrangement and/or sizing of the slots 232 may be different from (e.g., the opposite of) the sizing and/or arrangement of slots that may be utilized in a liquid distributor for medium or high pressure refrigerants, which generally include more open area of slots at the longitudinal ends 216 and/or portions of the shell 102 furthest from the refrigerant inlet 110, though it should be understood that the slot layout 230 may benefit operation of medium or high pressure refrigerants, in certain embodiments.

[0044] As a specific and non-limiting example, FIG. 11 is a cross-sectional side view of an embodiment of the liquid distributor 104 positioned within the shell 102 of the evaporator 38 and having a parabolic slot layout 340. The refrigerant inlet 110 provides the refrigerant 106 (e.g., two-phase refrigerant) to the distributor volume 222 of the liquid distributor 104, from which the refrigerant 106 is directed to the parabolic slot layout 340 for distribution to the refrigerant pool 112 and the tube bundles 124, as discussed above. As illustrated, the parabolic slot layout 340 of the present embodiment includes a single slot 342 (e.g., single cutout) formed along the side panel 160 of the liquid distributor 104. It should be understood that the other side panel 162, discussed above, may include a similar singular slot 342. The single slot 342 has a taper or parabolic curve shape, which provides a proximate slot height 344 (e.g., defined along the vertical axis 146) in a central portion 346 of the liquid distributor 104 above the refrigerant inlet 110 (e.g., at a common point 347 with the refrigerant inlet 110 along the longitudinal axis 250) that is larger than a distal slot height 348 of the single slot 342 at the longitudinal ends 216 of the liquid distributor 104. In other embodiments, the single slot 342 may have a linear taper that corresponds to a perimeter of an isosceles triangle having a summit positioned at the longitudinal midpoint 266 of the liquid distributor 104. In either case, this gradually- changing or sloped slot height provides a greater open area for the refrigerant 106 to exit from the central portion 346 of the liquid distributor 104 than from the longitudinal ends 216, thus more evenly distributing the refrigerant 106 along a length 350 of the liquid distributor 104. Indeed, as introduced above, a refrigerant passage 352 for dispersing the refrigerant 106 out of the distributor volume 222 of the liquid distributor 104 may be defined between edges of the single slot 342 of each side panel 160, 162 and the bottom portion 114 of the shell 102 discussed above. As such, the refrigerant passage 352 has a greater cross sectional area (e.g., defined between the longitudinal axis 250 and the vertical axis 146, defined as open area between shell-facing distal edges of the liquid distributor 104 and the shell 102) at positions that are closer to the refrigerant inlet 110.

[0045] As another example, FIG. 12 is a cross-sectional side view of an embodiment of the liquid distributor 104 having a height-variable slot layout 360. In particular, the height- variable slot layout 360 includes multiple slots 232 defined along the side panel 160 of the liquid distributor 104. Each slot 232 has a width 364 (e.g., defined along the longitudinal axis 250) of a common dimension or magnitude along the length 350 of the liquid distributor 104, in the present embodiment. Notably, the slots 232 that are closer to the refrigerant inlet 110 have a height 366 (e.g., defined along the vertical axis 146) that is greater than a height 368 of the slots 232 that are further from the refrigerant inlet 1 10. That is, as a position of the slot 232 along either of the directions 240 away from the refrigerant inlet 110 increases, a dimension or magnitude of the height of the slot 232 decreases. As such, the refrigerant passage 352 defined between lower edges of the liquid distributor 104 and the bottom portion 114 of the shell 102 has a greater open area at positions that are nearer the refrigerant inlet 110. In some embodiments, the height of the slots 232 of the height-variable slot layout 360 may decrease linearly or exponentially from one slot to another. For example, a proximate slot 370 nearest the refrigerant inlet 110 may have a height that is 20 percent greater than an adjacent slot 372. As such, the liquid distributor 104 may more effectively direct equal portions of the refrigerant 106 along the length 350, despite the variance in static velocity and mass flow of the refrigerant 106 discussed above.

[0046] Moreover, FIG. 13 is a cross-sectional side view of an embodiment of the liquid distributor 104 having a width-variable slot layout 380. As an alternative to the height- variable slot layout 360 discussed above, the present embodiment of the width-variable slot layout 380 defining the refrigerant passage 352 includes slots 232 which each have a height 382 (e.g., defined along the vertical axis 146) of a common dimension or magnitude. Notably, a width (e.g., defined along the longitudinal axis 250) of each slot 232 decreases in dimension or magnitude as a position of the slot 232 along either of the directions 240 along or parallel to the longitudinal axis 250 away from the refrigerant inlet 110 increases. Further, FIG. 14 is a cross-sectional side view of an embodiment of the liquid distributor 104 having a density -variable slot layout 400. In the present embodiment, the slots 232 of the density-variable slot layout 400 each have a height 402 (e.g., defined along the vertical axis 146) of a common dimension or magnitude and a width 404 (e.g., defined along the longitudinal axis 250) of a common dimension or magnitude. However, relative to the longitudinal axis 250, the slots 232 are positioned closer together in the central portion 346 of the liquid distributor 104, such that interim flanges 410 protruding between the slots 232 change in width. In other words, the interim flanges 410 are wider in the central portion 346 than they are adjacent the longitudinal ends 216 of the liquid distributor 104, providing similarly-sized slots 232 that are at a greater density when positioned closer to the refrigerant inlet 110. This spacing of similarly-sized slots 232 may be another effective manner for providing the refrigerant passage 352 having additional open area from the liquid distributor 104 nearest to the refrigerant inlet 110.

[0047] It should be understood that features of the embodiments of FIGS. 11-14 may also be combined in some embodiments to provide the refrigerant passage 352 having a greater open area for the slots 232 at the central portion 346 than at the longitudinal ends 216. For example, the slots 232 may be taller, wider, and/or denser at the central portion 346, progressing to shorter, narrower, and/or sparser slots 232 at the longitudinal ends 216 of the liquid distributor 104. Moreover, in other embodiments, the refrigerant inlet 110 may be positioned proximate one of the longitudinal ends 216, and the single slot 342 or multiple slots 232 may be sized with a greater open area near the refrigerant inlet 110 than near the opposite longitudinal end 216.

[0048] As set forth above, the present disclosure may provide one or more technical effects useful in distributing refrigerant (e.g., two-phase refrigerant, liquid-vapor refrigerant, low pressure refrigerant, etc.) within a refrigerant pool of a flooded evaporator. For example, the evaporator may include a liquid distributor, which has a slot layout with slots defined within lower edge portions of side panels of the liquid distributor. A refrigerant inlet supplies the refrigerant into the liquid distributor, which causes relatively lower mass flows of the refrigerant out of the slots that are nearer to the refrigerant inlet than the slots that are further from the refrigerant inlet. Accordingly, the present embodiments of the slot layout more efficiently distribute the refrigerant by positioning larger open areas or refrigerant flow paths in portions of the liquid distributor closest to the refrigerant inlet. These larger open areas thereby provide more opportunities for the refrigerant to exit the liquid distributor and decrease in static pressure. The slot layout may have multiple different physical configurations, such as taller, wider, and/or denser slots near the refrigerant inlet to more efficiently distribute the refrigerant therefrom. By more evenly distributing the refrigerant along a length of the liquid distributor, the liquid distributor may therefore improve heat transfer performance and operation of the evaporator. The technical effects and technical problems in the specification are examples and are not limiting. It should be noted that the embodiments described in the specification may have other technical effects and can solve other technical problems.

[0049] When introducing elements of various embodiments of the present disclosure, the articles“a,”“an,” and“the” are intended to mean that there are one or more of the elements. The terms“comprising,”“including,” and“having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to“one embodiment” or“an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0050] While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

Claims

CLAIMS:

1. A flooded evaporator for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising:

a shell defining an interior volume;

a refrigerant inlet configured to direct a two-phase refrigerant into the shell; and a liquid distributor disposed within the interior volume of the shell and configured to receive the two-phase refrigerant from the refrigerant inlet, wherein the liquid distributor comprises:

a main body coupled to a bottom portion of the shell and separating the interior volume of the shell into a distributor volume and a remaining volume; and

a refrigerant passage formed in the main body and fluidly coupling the distributor volume and the remaining volume, wherein the refrigerant passage comprises a first portion and second portion, the first portion comprises a first cross-sectional area greater than a second cross-sectional area of the second portion, and the first portion is closer to the refrigerant inlet than the second portion.

2. The flooded evaporator of claim 1, wherein the refrigerant inlet is positioned at a longitudinal midpoint of the liquid distributor.

3. The flooded evaporator of claim 2, wherein the first portion is positioned at the longitudinal midpoint, and wherein the second portion is positioned distal to the longitudinal midpoint.

4. The flooded evaporator of claim 3, wherein the second portion is positioned at a longitudinal end of the liquid distributor.

5. The flooded evaporator of claim 1, wherein the first portion comprises a first plurality of slots formed in a first edge and a second edge of the main body, and wherein the second portion comprises a second plurality of slots formed in the first edge and the second edge of the main body.

6. The flooded evaporator of claim 1, wherein the first portion comprises a first slot formed in an edge of the main body, and the second portion comprises a second slot formed in the edge of the main body.

7. The flooded evaporator of claim 6, wherein the first slot has a first height greater than a second height of the second slot.

8. The flooded evaporator of claim 6, wherein the first slot has a first width greater than a second width of the second slot.

9. The flooded evaporator of claim 1, wherein the refrigerant passage is defined by a single cutout formed in the main body, and wherein the single cutout comprises a taper extending along a longitudinal axis of the liquid distributor.

10. The flooded evaporator of claim 1, wherein the refrigerant passage is defined by a parabolic-shaped cutout formed in the main body, wherein the parabolic shaped cutout is gradually reduced in height from the first portion of the refrigerant passage to the second portion of the refrigerant inlet.

11. The flooded evaporator of claim 1, wherein the first portion comprises a first plurality of slots spaced along the main body at a first density, the second portion comprises a second plurality of slots spaced along the main body at a second density, and the first density is greater than the second density.

12. The flooded evaporator of claim 1, wherein the main body comprises a first panel coupled to the bottom portion of the shell via a first edge of the first panel and comprises a second panel coupled to the bottom portion via a second edge of the second panel, and wherein the refrigerant passage comprises a first plurality of slots formed in the first edge and comprises a second plurality of slots formed in the second edge.

13. A flooded evaporator of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising:

a shell defining an interior volume;

a refrigerant inlet formed in the shell and configured to direct a two-phase refrigerant into the shell; and

a liquid distributor disposed within the interior volume of the shell and configured to receive the two-phase refrigerant from the refrigerant inlet, wherein the liquid distributor comprises:

a main body comprising at least one panel coupled to a bottom portion of the shell and separating the interior volume of the shell into a distributor volume and a remaining volume, wherein the at least one panel comprises a first edge and a second edge; and

a slot arrangement formed in the first edge and the second edge of the at least one panel, wherein the slot arrangement defines a refrigerant passage that fluidly couples the distributor volume and the remaining volume, and wherein an open cross- sectional area of the slot arrangement decreases along a longitudinal axis extending from the refrigerant inlet.

14. The flooded evaporator of claim 13, wherein the slot arrangement comprises a first parabolic-shaped slot formed in the first edge and comprises a second parabolic-shaped slot formed in the second edge.

15. The flooded evaporator of claim 13, wherein the slot arrangement comprises a first plurality of slots formed in the first edge and comprises a second plurality of slots formed in the second edge.

16. The flooded evaporator of claim 15, wherein a first portion of the first plurality of slots and the second plurality of slots is defined at a common point along the longitudinal axis as the refrigerant inlet, wherein a second portion of the first plurality of slots and the second plurality of slots is defined a distance from the refrigerant inlet along the longitudinal axis, and wherein the first portion comprises a greater slot height, slot width, slot density, or combination thereof than the second portion.

17. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising:

a flooded evaporator configured to evaporate a two-phase refrigerant into a refrigerant vapor, wherein the flooded evaporator comprises:

a shell defining an interior volume, wherein the shell comprises a first longitudinal end portion and a second longitudinal end portion;

a refrigerant inlet configured to direct the two-phase refrigerant into the shell at a longitudinal position between the first longitudinal end portion and the second longitudinal end portion; and

a liquid distributor disposed within the interior volume of the shell, wherein the liquid distributor comprises:

a main body coupled to a bottom portion of the shell, wherein the main body extends from the first longitudinal end portion of the shell to the second longitudinal end portion of the shell, and wherein the main body defines a distributor volume configured to receive the two-phase refrigerant from the refrigerant inlet; and a slot arrangement formed in the main body and configured to direct the two-phase refrigerant out of the distributor volume, wherein the slot arrangement comprises a varied open cross-sectional area that is greater proximate the refrigerant inlet than near the first longitudinal end portion and the second longitudinal end portion.

18. The HVAC&R system of claim 17, wherein the slot arrangement comprises a first slot defined on an edge of the main body proximate the refrigerant inlet and comprises a second slot defined on the edge proximate the first longitudinal end portion, and wherein the first slot comprises a greater height, width, or combination thereof than the second slot.

19. The HVAC&R system of claim 17, wherein the slot arrangement comprises a tapered slot extending along an edge of the main body from the first longitudinal end portion of the shell to the second longitudinal end portion of the shell.

20. The HVAC&R system of claim 17, wherein the main body comprises a radial cross-section having a rectangular shape, a triangular shape, or a ladder shape.