WO2008112549A2

WO2008112549A2 - Heat exchanger

Info

Publication number: WO2008112549A2
Application number: PCT/US2008/056222
Authority: WO
Inventors: Alexander Cohr Pachai; John Ritmann; Istvan Knoll; Saisunee Jommed; Jose Augusto Castro Chagas; Francisco Cazorla Marcos
Original assignee: Johnson Controls Technology Company
Priority date: 2007-03-09
Filing date: 2008-03-07
Publication date: 2008-09-18
Also published as: WO2008112549A3; WO2008112569A2; WO2008112593A1; WO2008112566A3; WO2008112594A3; WO2008112594A2; WO2008112568A3; WO2008112568A2; WO2008112572A1; WO2008112569A3; WO2008112591A2; WO2008112554A1; WO2008112591A3; WO2008112566A2

Abstract

A heat exchanger includes a hollow member having an inlet and an outlet for receiving a first fluid selected from the group comprising ammonia, hydrocarbon based refrigerants, hydrofluorocarbon based refrigerants or carbon dioxide. A structure is configured to receive the inlet and outlet, the inlet and outlet extending through the structure and forming a fluid tight seal therebetween. The hollow member is configured to be received in an opening formed in a vessel configured to receive a second fluid that is in thermal communication with the hollow member, the structure and vessel forming a fluid tight seal along the opening.

Description

HEAT EXCHANGER

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 60/894,052, entitled SYSTEMS AND METHODS OF USING CO2 IN REFRIGERATION AND AIR CONDITIONING APPLICATIONS, filed March 9, 2007, and U.S. Provisional Application No. 60/917,175, entitled SYSTEMS AND METHODS OF USING NATURAL REFRIGERANTS, filed May 10, 2007, which are hereby incorporated by reference.

BACKGROUND

[0002] The application generally relates to multistage refrigeration systems. The application relates more specifically to heat exchanger configurations for multistage refrigeration systems.

[0003] A multistage refrigeration system (also referred to as a cascade refrigeration system or a multi-pressure refrigeration system) can be used when several evaporators are needed to provide various temperatures for a single application. For example, a multistage refrigeration system can be used to provide the necessary cooling for both refrigerated cases and freezer cases in a supermarket. A multistage refrigeration system can also be used to provide an evaporator temperature lower than that attainable by a single-stage system, e.g., a vapor compression system. For example, a multistage refrigeration system can be used in an industrial process to provide temperatures of between -20 deg. C and -50 deg. C or colder, such as may be required in a plate freezer application.

[0004] One type of multistage refrigeration system, including heat exchangers, can involve the interconnection of two or more closed loop refrigeration systems in which the heat-absorbing stage, e.g., evaporator, of one system is in a heat exchange relationship with the heat-rejecting stage, e.g., condenser, of the other system. One of the primary purposes of a multistage refrigeration system having the heat-absorbing stage of one system in a heat exchange relationship with the heat-rejecting stage of the other system is to permit the attaining of temperatures in the heat-rejecting or heat-absorbing stage of one of the systems that exceeds that which can be attained if only a single system is used with conventional heat-rejecting or heat-absorbing loads.

SUMMARY

[0005] The present invention relates to a heat exchanger including a heat exchanger including a hollow member having an inlet and an outlet for receiving a first fluid selected from the group comprising ammonia, hydrocarbon based refrigerants, hydrofluorocarbon based refrigerants or carbon dioxide. A structure is configured to receive the inlet and outlet, the inlet and outlet extending through the structure and forming a fluid tight seal therebetween. The hollow member is configured to be received in an opening formed in a vessel configured to receive a second fluid that is in thermal communication with the hollow member, the structure and vessel forming a fluid tight seal along the opening.

[0006J The present invention also relates to a heat exchanger including an inlet tube, an outlet tube and a structure configured to receive the inlet tube and outlet tube. The inlet tube and outlet tube extend through the structure and form a fluid tight seal therebetween. A plurality of plates is provided. Each plate is configured to have a piping connection from the inlet tube to the outlet tube for transporting a fluid from the inlet tube to the outlet tube. The fluid is selected from the group comprising ammonia, hydrocarbon based refrigerants, hydrofluorocarbon based refrigerants or carbon dioxide. The plurality of plates and the inlet tube and the outlet tube are configured to be received in an opening formed in a vessel, the structure and vessel forming a fluid tight seal along the opening.

[0007] The present invention further relates to a cooling system including a first system portion configured to circulate a fluid through a compressor, a heat exchanger, a vessel, a first pump and a first evaporator. A second system portion is configured to circulate the fluid through a separator, a second pump, a second evaporator, returning to the separator, and then returning to the compressor of the first system portion. The vessel of the first system portion is in fluid communication with the separator of the second system portion. Upon liquid fluid accumulating within the vessel above a predetermined level, an amount of liquid fluid is provided to the separator.

BRIEF DESCRIPTION OF THE FIGURES

[0008] FIGS. 1 and 2 show exemplary embodiments of commercial and industrial applications incorporating a refrigeration system.

[0009] FIG. 3 shows a perspective view of an exemplary embodiment of a refrigeration system.

[0010] FIG. 4 shows a side elevational view of the refrigeration system shown in FIG. 3.

[0011] FIG. 5 schematically illustrates an exemplary embodiment of a multistage refrigeration system.

[0012] FIG. 6 is a perspective view of an exemplary embodiment of a heat exchanger.

[0013] FIG. 6A shows a cross-section taken along line 6A-6A of FIG. 6. [0014] FIG. 6B shows a cross-section taken along line 6B-6B of FIG. 6.

[0015] FIG. 7 shows a partially cutaway view of an alternate exemplary embodiment of a heat exchanger.

[0016] FIG. 7A shows a cross-section taken along line 7A-7A of FIG. 7. [0017] FIG. 8 shows a further exemplary embodiment of a heat exchanger.

[0018] FIG. 9 schematically illustrates an alternate exemplary embodiment of a multistage refrigeration system. DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0019] FIGS. 1 and 2 illustrate several exemplary applications for a multistage refrigeration system (also referred to as a cascade refrigeration system or a multi -pressure refrigeration system). Multistage refrigeration systems can include a first stage system portion (also referred to as a high side system portion) and a second stage system portion (also referred to as a low side system portion) that are interconnected by a heat exchanger and can be used to provide different levels of cooling capacity and/or achieve low temperatures that are difficult to achieve with a single vapor compression cycle. FIG. 1 shows a multistage refrigeration system 10 that can provide both refrigeration and freezing capacity for a supermarket 12 in a commercial setting. The second stage system of multistage refrigeration system 10 can have evaporators incorporated into refrigerated cases or displays 14 and freezer cases or displays 16 that are accessible by a person shopping in supermarket 12. According to an exemplary embodiment, refrigerated cases or displays 14 can be used to keep produce or dairy products at a preselected temperature and can be operated at a temperature between about 2 deg C and about 7 deg C, and freezer cases or displays 16 can be used to keep frozen items at a preselected temperature and can be operated at a temperature between about -20 deg C and about -30 deg C. The second stage system of multistage refrigeration system 10 can have an evaporator 18 in a freezer storage area 20 of supermarket 12 and can have an evaporator 22 in a refrigerated storage area 24 of supermarket 12. According to an exemplary embodiment, freezer storage area 20 can be used to store items to be subsequently placed in freezer cases or displays 16 at a preselected temperature and can be operated at a temperature between about -20 deg C and about -30 deg C, and refrigerated storage area 24 can be used to store items to be subsequently placed in refrigerated cases or displays 14 at a preselected temperature and can be operated at a temperature between about 2 deg C and about 7 deg C.

[0020] FIG. 2 shows the use of a multistage refrigeration system 10 as a plate freezer 28 in a factory or industrial setting 26. Plate freezer 28 may have horizontal or vertical plates 30 to freeze flat products, such as pastries, fish fillets, and beef patties, as well as irregular-shaped vegetables that are packaged in brick-shaped containers, such as asparagus, cauliflower, spinach, and broccoli. The product may be firmly pressed between metal plates 30 that are cooled to subfreezing temperatures by internally circulating refrigerant from the second stage system through thin channels within plates 30. A high rate of heat transfer can be obtained between the product and plates 30. According to an exemplary embodiment, plate freezers 28 may provide cooling temperatures of between about -20 deg C and about -50 deg C or colder and can be used when rapid freezing is desired to retain product flavor and freshness. Once the product is frozen between plates 30, the product may be difficult to remove from plate freezer 28 because the product may be frozen to plates 30. A defrost system that warms plates 30 but does not thaw the product between plates 30 is used to assist in the removal of the product from between plates 30.

[0021] FIGS. 3 through 5 show a multistage refrigeration system (shown schematically in FIG. 5). The multistage refrigeration system can include a first stage system portion 32 and a second stage system portion 34 that are interconnected by a heat exchanger 36. Heat exchanger 36 can be a plate heat exchanger, a shell and tube heat exchanger, a plate and shell heat exchanger or any other suitable type of heat exchanger. First stage system portion 32 can be a vapor compression system that circulates a refrigerant through a compressor 38, a condenser 40, a receiver 42 (optional), an expansion device 44, and an evaporator 46 that is incorporated into heat exchanger 36. Some examples of fluids that may be used as refrigerants in first stage system portion 32 are carbon dioxide (CO2; for example, R-744), nitrous oxide (N2O; for example, R- 744A), ammonia (NH3; for example, R-717), hydro fiuorocarbon (HFC) based refrigerants (for example, R-410A, R-407C, R-404A, R- 134a), other low global warming potential (GWP) refrigerants, and any other suitable type of refrigerant.

[0022] Second stage system portion 34 can be a vapor compression system that circulates a refrigerant through a compressor 48, a condenser 50 that is incorporated into heat exchanger 36, a receiver or separator 52, a pump 54, and a first expansion device 56 and a first evaporator 58 that can be in parallel with a second device 60, such as a valve, and second evaporator 62. According to another exemplary embodiment, second stage system portion 34 can be operated with only first expansion device 56 and first evaporator 58. According to still another exemplary embodiment, second stage system portion 34 can be operated as a volatile system by removing compressor 48, first expansion device 56 and first evaporator 58. Some examples of fluids that may be used as refrigerants in second stage system portion 34 are carbon dioxide (C 02; for example, R- 744), nitrous oxide (N2O; for example, R-744A), or mixtures of carbon dioxide and nitrous oxide, or hydrocarbon based refrigerants (for example, R-170). When second stage system portion 34 is operated as a volatile system, the refrigerant circulating through the system can be replaced with a glycol solution or a brine solution.

[0023J In first stage system portion 32, when operated sub-critically, i.e., below the critical pressure for the refrigerant being circulated in first stage system portion 32, compressor 38 compresses a refrigerant vapor and delivers the compressed vapor to condenser 40 through a discharge line. Compressor 38 can be a screw compressor, reciprocating compressor, centrifugal compressor, rotary compressor, swing link compressor, scroll compressor, turbine compressor, or any other suitable type of compressor. The refrigerant vapor delivered by compressor 38 to condenser 40 enters into a heat exchange relationship with a fluid, e.g., water from a cooling tower, and undergoes a phase change to a refrigerant liquid as a result of the heat exchange relationship with the fluid. The condensed liquid refrigerant from condenser 40 can be stored in receiver 42 before flowing through expansion device 44 to evaporator 46 in heat exchanger 36.

[0024] The condensed liquid refrigerant delivered to evaporator 46 in heat exchanger 36 enters into a heat exchange relationship with the fluid being circulated in condenser 50 in heat exchanger 36 by second stage system portion 34, and undergoes a phase change to a refrigerant vapor as a result. The vapor refrigerant in evaporator 46 exits evaporator 46 and returns to compressor 38 by a suction line to complete the cycle.

[0025] First stage system portion 32 can be operated as a transcritical or supercritical system. During transcritical operation, first stage system portion 32 can be operated partly below (sub-critical) and partly above (supercritical) the critical pressure of the refrigerant circulated in first stage system portion 32. The discharge pressure of compressor 38 (or high side pressure) can be greater than the critical pressure of the refrigerant, e.g., 73 bar at 31 deg C for carbon dioxide. Furthermore, during transcritical operation, the refrigerant is maintained as a single phase refrigerant (vapor) in the high pressure side of first stage system portion 32 and is first converted into the liquid phase when it is expanded in expansion device 44. When operated as a transcritical system, the refrigerant from compressor 38 flows to a gas cooler (which can operate as a condenser in low ambient temperatures permitting the system to operate sub-critical) that cools the refrigerant by heat exchange with another fluid. The cooling of the refrigerant gradually increases the density of the refrigerant. During transcritical operation of first stage system portion 32, the high side pressure can be modulated to control capacity or to optimize the coefficient of performance by regulating the refrigerant charge and/or by regulating the total internal high side volume of refrigerant.

[0026] In second stage system portion 34, compressor 48 compresses a refrigerant vapor and delivers the compressed vapor to condenser 50 through a discharge line. Compressor 48 can be a screw compressor, reciprocating compressor, centrifugal compressor, rotary compressor, swing link compressor, scroll compressor, turbine compressor, or any other suitable type of compressor. The refrigerant vapor delivered by compressor 48 to condenser 50 in heat exchanger 36 enters into a heat exchange relationship with the fluid being circulated in evaporator 46 by first stage system portion 32, and undergoes a phase change to a refrigerant liquid as a result. The condensed liquid refrigerant from condenser 50 is circulated to receiver 52. The liquid refrigerant in receiver 52 is circulated to first expansion device 56 and first evaporator 58 and then to second device 60 and second evaporator 62 by pump 54.

[0027] In first evaporator 58, the liquid refrigerant from first expansion device 56 enters into a heat exchange relationship with a cooling load, e.g., a fluid, and undergoes a phase change to a refrigerant vapor as a result. The refrigerant vapor in first evaporator 58 exits first evaporator 58 and returns to compressor 48 to complete the cycle. In second evaporator 62, the liquid refrigerant from second device 60 enters into a heat exchange relationship with a cooling load, e.g., a fluid, and may undergo a phase change to a refrigerant vapor as a result. However, according to one exemplary embodiment, the amount of refrigerant liquid provided to second evaporator 62 may exceed the heat exchange capabilities of the cooling load and less than all of the liquid refrigerant can undergo a phase change and the refrigerant fluid leaving second evaporator 62 may be a mixture of refrigerant vapor and refrigerant liquid. The refrigerant fluid exiting second evaporator 62, whether refrigerant vapor or a mixture of refrigerant vapor and refrigerant liquid, returns to the receiver 52. Receiver 52 can also have a connection to the discharge line from compressor 48 to provide refrigerant vapor from receiver 52 to the discharge line and subsequently to the condenser 50 in heat exchanger 36.

[0028] Compressor 38 of first stage system portion 32 and compressor 48 of second stage system portion 34 can each be driven by a motor or drive mechanism. The motor used with compressor 38 or compressor 48 can be powered by a variable speed drive (VSD) or can be powered directly from an alternating current (AC) or direct current (DC) power source. The VSD, if used, receives AC power having a particular fixed line voltage and fixed line frequency from the AC power source and provides power having a variable voltage and frequency to the motor. The motor used with compressor 38 or compressor 48 can be any type of electric motor that can be powered by a VSD or directly from an AC or DC power source. For example, the motor used with compressor 38 or compressor 48 can be a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or any other suitable motor type. In an alternate embodiment, other drive mechanisms such as steam or gas turbines or engines and associated components can be used to drive the motor used with compressor 38 or compressor 48.

[0029] FIG. 6 shows a heat exchanger 64 that allows two refrigerant fluids flowing through heat exchanger 64 to exchange heat with each other without mixing. It is to be understood that the terms refrigerant, fluid or refrigerant fluid, irrespective of phase qualifier, such as vapor phase fluid, may be used interchangeably. Heat exchanger 64 includes a vessel 66 having a hollow body 70 disposed between opposed end structures 86 and 88. An inlet tube 68 has an inlet 72 for providing a substantially liquid phase fluid, generally indicated by an arrow 108, to heat exchanger 64. Openings formed in inlet tube 68 dispense fluid 108 inside of heat exchanger 64, and fluid 108 accumulates within heat exchanger 64 as indicated generally by fluid 110 shown in FIG. 6B. Inlet tube 68 includes two ends: an end 78 that abuts structure 86 and an opposite end 80 that abuts structure 88. An outlet tube 74 has an outlet 76 for discharging a substantially vapor phase fluid, generally indicated by an arrow 114, from heat exchanger 64. Outlet tube 76 includes two ends: an end 82 that abuts structure 86 and an opposite end 84 that abuts structure 88. According to some exemplary embodiments, inlet and outlet rubes 68 and 74 may be configured differently than as shown in FIG. 6. For example, in an alternate embodiment, indicated generally by dashed lines, an end 92 of outlet tube 74 extends through structure 86, providing a second outlet for discharging fluid 102 from heat exchanger 64.

[0030] As further shown in FIGS. 6, 6A, and 6B, heat exchanger 64 includes an inlet tube 94 and an outlet tube 96 each extending through a plurality of plates 98 spaced apart from each other between opposed structures 86 and 88. hi one embodiment, plates 98 are disposed substantially parallel and are substantially equally spaced from each other. In another embodiment, inlet and outlet tubes 94 and 96, plates 98 and at least one structure 86 or 88 are an integrated unit. In a further embodiment, inlet tube 94 is disposed proximate to a central portion of structure 86 and outlet tube 96 is disposed proximate to a lower portion of structure 86. Designation of inlet tube 94 and outlet tube 96 is made with respect to structure 86, for example, inlet fluid flows into inlet tube 94, as indicated generally by reference numeral 104, and outlet fluid exits from outlet tube 96, as indicated generally by reference numeral 106, and is not to be considered limiting, as tubes 94 and 96 are part of a two-pass fluid arrangement circulating the same fluid.

[0031] According to an exemplary embodiment, to increase the amount of heat exchange between the two fluids, a piping connection 100 in plate 98 is provided between inlet and outlet tubes 94 and 96. However, the direction of fluid flow through the tubes may also be reversed. According to a further exemplary embodiment, the piping connection may be serpentine or define another profile.

[0032] Plates 98 and inlet and outlet tubes 94 and 96 are substantially immersed in liquid phase fluid 110 located within heat exchanger 64. Due to exchange of heat between the fluid flowing through inlet and outlet tubes 94 and 96 and liquid phase fluid 110, liquid phase fluid 110 undergoes a phase change to become a vapor phase fluid 112. Vapor phase fluid 112 accesses openings 90 formed in outlet tube 74 and exits at outlet 76 as a discharged vapor phase fluid 114. According to an embodiment, the openings are sized using a high degree of precision to achieve substantially uniform flow of vapor phase fluid 1 12 along the length of the heat exchanger. For example, the openings may be formed in the outlet tube using a high intensity light beam, such as a laser.

[0033] FIGS. 7 and 7A show a heat exchanger 1 16, which is an alternate embodiment of heat exchanger 64. Heat exchanger 116 includes an inlet tube 122 and an outlet tube 124 that are disposed in a non-vertical arrangement in a body 118. Inlet and outlet tubes 122 and 124 extend through a plurality of plates 126 disposed in a body 118 and through a structure 120 disposed at one end of heat exchanger 116. Plates 126 include pipe connections 128 extending between inlet and outlet tubes 122 and 124 in a serpentine profile. A junction 130 connects pipe connection 128 with inlet tube 122 and a junction 132 connects pipe connection 128 with outlet tube 124.

[0034] FIG. 8 shows an alternate embodiment of a heat exchanger 134 that allows two refrigerant fluids flowing through heat exchanger 134 to exchange heat with each other without mixing. Heat exchanger 134 includes a vessel 136 defining a hollow body having an opening 138. Opening 138, which is circular in one embodiment, includes a mounting flange 162. Vessel 136 further includes an inlet 150 for permitting a fluid, indicated generally by an arrow 154, to enter vessel 136, accumulate inside vessel 136 as fluid 156, and an outlet 152 to discharge fluid 156 from vessel 136 as discharged fluid, indicated generally by an arrow 158.

[0035] A hollow member 140 is configured to be inserted inside heat exchanger 134 through opening 138. Hollow member 140 includes an inlet 142 for receiving an inlet flow of fluid, indicated generally by an arrow 146, into hollow member 140 and an outlet 144 for discharging an outlet flow of fluid, indicated generally by an arrow 148, from hollow member 140. According to another exemplary embodiment, hollow member 140 has a serpentine profile. [0036] Inlet 142 and outlet 144 of hollow member 140 are connected to a structure 160 that is configured to form a fluid tight seal between inlet 142 and structure 160 and between outlet 144 and structure 160. According to another exemplary embodiment, the inlet and outlet each extend from a manifold (not shown) formed in the structure. Hollow member 140 and structure 160 may provide sufficient support to permit hollow member 140 to be cantilevered when installed in heat exchanger 134; however, supports also may be used to provide support for hollow member 140 to prevent possible collapse of hollow member 140.

[0037] Structure 160 includes a mounting flange 164 that corresponds to mounting flange 162. The two flanges 162 and 164 may be brought together by a mechanical fastener 166 to form a fluid tight seal therebetween. It is to be understood that mating mounting flanges 162 and 164 are selectably separable, such as for maintenance. According to some exemplary embodiments, one or both of mounting flanges may include indexing features (not shown) to assist with alignment during assembly.

[0038] The construction of heat exchanger 134 is configured for many different fluids that can be used as refrigerants including, but not limited to, carbon dioxide, nitrous oxide, ammonia, hydrocarbon and hydrofluorocarbon based refrigerants. For example, carbon dioxide may be introduced at inlet 150 with carbon dioxide liquid collecting at the bottom of vessel 136 for discharge from vessel 136 at outlet 152, while ammonia, hydrocarbon and hydrofluorocarbon based refrigerants may be introduced into hollow member 140 at inlet 142 and discharged from hollow member 140 at outlet 144, although the functions of inlet 142 and outlet 144 may be reversed, as required, for efficient operation.

[0039] FIG. 9 shows an exemplary embodiment of a cooling system, similar to that shown in FIG. 5, using a heat exchanger 174 similar to one discussed with respect to Figures 6-8. The cooling system includes a first stage system portion 168, similar to first stage system portion 32 shown in FIG. 3, that circulates a refrigerant fluid through a compressor 172, heat exchanger 174, a vessel 176, a pump 178 (a pair of pumps 178 is shown in FIG. 9), and a first evaporator 180. A portion of refrigerant fluid provided to heat exchanger 174 is provided by an expansion device 190, with the refrigerant fluid provided by expansion device 190 being provided to a first stage compressor 192. The cooling system includes a second stage system portion 170, similar to second stage system 34 shown in FIG. 5, that circulates the refrigerant fluid through a separator 182, a pump 184 (a pair of pumps 184 is shown in FIG. 9), and a second evaporator 186, From second evaporator 186, the refrigerant fluid returns to separator 182 and then flows to compressor 172 of first stage system portion 168.

[0040] Vessel 176 of first stage system portion 168 is located downstream of heat exchanger 174 and is in selectable fluid communication with separator 182 due to a valve disposed between separator 182 and vessel 176. According to an exemplary embodiment, the vessel defines a segment of piping that is substantially vertically disposed, having a predetermined vertical height. When there is insufficient liquid refrigerant fluid contained within vessel 176, for example, below a predetermined level 188, a valve 194 disposed between separator 182 and vessel 176 remains closed. However, when a sufficient amount of liquid refrigerant fluid accumulates within vessel 176, for example, above a predetermined level 188, an amount of liquid refrigerant fluid is provided to separator 182. The arrangement of vessel 176 and valve 194 functions to eliminate the need for a receiver, thereby reducing the cost of the system.

[0041] While only certain features and embodiments of the invention have been illustrated and described herein, 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. 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 invention. 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 invention, or those unrelated to enabling the claimed invention). 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

WHAT IS CLAIMED IS:

1. A heat exchanger comprising: a hollow member having an inlet and an outlet for receiving a first fluid selected from the group comprising ammonia, hydrocarbon based refrigerants, hydrofluorocarbon based refrigerants or carbon dioxide; a structure configured to receive the inlet and outlet, the inlet and outlet extending through the structure and forming a fluid tight seal therebetween; and wherein the hollow member is configured to be received in an opening formed in a vessel configured to receive a second fluid that is in thermal communication with the hollow member, the structure and vessel forming a fluid tight seal along the opening.

2. The heat exchanger of claim 1, wherein the hollow member and structure are an integrated unit.

3. The heat exchanger of claim 1, wherein the hollow member is a tube arrangement.

4. The heat exchanger of claim 3, wherein the hollow member is supported by the structure.

5. The heat exchanger of claim 1, wherein the hollow member is serpentine.

6. The heat exchanger of claim 1, wherein the opening is circular.

7. The heat exchanger of claim 1, wherein the vessel includes an inlet and an outlet.

8. The heat exchanger of claim 1, wherein the inlet is disposed proximate a central portion of the vessel and the outlet is disposed along a lower portion of the vessel.

9. The heat exchanger of claim 1, wherein the outlet is disposed proximate a central portion of the vessel and the inlet is disposed along a lower portion of the vessel.

10. The heat exchanger of claim 1, wherein the structure includes a manifold.

11. The heat exchanger of claim 1, wherein the vessel and structure have mating mounting flanges.

12. The heat exchanger of claim 11, wherein the vessel and structure are selectahly separable.

13. The heat exchanger of claim 11, wherein the mating mounting flanges include mating features to secure the mating flanges together.

14. The heat exchanger of claim 11, wherein removable mechanical fasteners secure the mating flanges together.

15. A heat exchanger comprising: an inlet tube; an outlet tube; a structure configured to receive the inlet tube and outlet tube, the inlet tube and outlet tube extending through the structure and forming a fluid tight seal therebetween; a plurality of plates, each plate is configured to have a piping connection from the inlet tube to the outlet tube for transporting a fluid from the inlet tube to the outlet tube, the fluid selected from the group comprising ammonia, hydrocarbon based refrigerants, hydrofluorocarbon based refrigerants or carbon dioxide; and wherein the plurality of plates and the inlet tube and the outlet tube are configured to be received in an opening formed in a vessel, the structure and vessel forming a fluid tight seal along the opening.

16. The heat exchanger of claim 15, wherein a path of at least one of the piping connection is serpentine.

17. The heat exchanger of claim 15, wherein the structure, the inlet tube, the outlet tube and the plurality of plates are an integrated unit.

18. A cooling system comprising: a first system portion configured to circulate a fluid through a compressor, a heat exchanger, a vessel, a first pump and a first evaporator; a second system portion configured to circulate the fluid through a separator, a second pump, a second evaporator, returning to the separator, and then returning to the compressor of the first system portion; the vessel of the first system portion being in fluid communication with the separator of the second system portion; and wherein upon liquid fluid accumulating within the vessel above a predetermined level, an amount of liquid fluid is provided to the separator.

19. The cooling system of claim 18, wherein the vessel is a tube.

20. The cooling system of claim 18, wherein a valve is disposed between the vessel and the separator.