US20110073291A1

US20110073291A1 - Cooling module for a vehicle

Info

Publication number: US20110073291A1
Application number: US12/570,452
Authority: US
Inventors: Zaiqian Hu
Original assignee: Valeo Inc
Current assignee: Valeo Inc
Priority date: 2009-09-30
Filing date: 2009-09-30
Publication date: 2011-03-31

Abstract

A cooling module for a vehicle includes a combo cooler associated with a vehicle. A heat rejecter includes tubes arranged in a planar configuration. A low temperature radiator is associated with the heat rejecter and includes low temperature radiator tubes arranged in a planar configuration. Manifolds are independently configured to supply a refrigerant to the heat rejecter and a coolant to the low temperature radiator. A high temperature radiator is disposed adjacent and parallel to the combo cooler, and downstream of the combo cooler relative to an air stream flowing through the combo cooler and the high temperature radiator. The high temperature radiator is associated with a high temperature cooling loop of the vehicle, and cools an other coolant flowing therethrough. An operating temperature of refrigerant in the heat rejecter and an operating temperature of coolant in the low temperature radiator are lower than an operating temperature of the other coolant in the high temperature radiator.

Description

BACKGROUND

The present disclosure relates generally to cooling modules. Hybrid electric vehicles are often powered by an internal combustion engine and an electric motor, where each typically operates at different temperature ranges. Due, at least in part, to such different operating temperature ranges, cooling requirements for the internal combustion engine and the electric motor may, in some instances, be different.

SUMMARY

A cooling module for a vehicle is disclosed herein. The cooling module includes a combo cooler operatively associated with a vehicle. The combo cooler includes i) a heat rejecter having a plurality of heat rejecter tubes operatively connected thereto, where the heat rejecter tubes are arranged in a substantially planar configuration, ii) a low temperature radiator operatively associated with the heat rejecter and in fluid communication with a low temperature cooling loop of the vehicle, where the low temperature radiator has a plurality of low temperature radiator tubes operatively connected thereto and arranged in a substantially planar configuration, iii) a manifold opposed to and substantially parallel to an other manifold, where the manifold and the other manifold are each operatively connected to the plurality of heat rejecter tubes and the plurality of low temperature radiator tubes, and where the manifold and the other manifold are also independently configured to supply a refrigerant to the heat rejecter and a coolant to the low temperature radiator, and iv) at least one fin disposed between each one of the condenser tubes and the low temperature radiator tubes. A high temperature radiator is disposed adjacent and substantially parallel to the combo cooler and downstream of the combo cooler relative to an air stream flowing through the combo cooler and the high temperature radiator. The high temperature radiator is operatively associated with a high temperature cooling loop of the vehicle, where the high temperature radiator is configured to cool an other coolant flowing therethrough. Further, an operating temperature of the refrigerant in the heat rejecter and an operating temperature of the coolant in the low temperature radiator, are lower than the temperature of the other coolant in the high temperature radiator.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.

FIG. 1 schematically depicts an example of a known cooling module for an internal combustion engine;

FIG. 2 is a fluid flow diagram for a condenser of the cooling module of FIG. 1;

FIG. 2A is a fluid flow diagram for a gas heat exchanger of the cooling module of FIG. 1;

FIG. 3 is a fluid flow diagram for a high temperature radiator of the cooling module of FIG. 1;

FIG. 4 schematically depicts a known cooling module for a vehicle having a low temperature cooling loop and a high temperature cooling loop;

FIG. 5 is a fluid flow diagram for a low temperature radiator of the cooling module for a low temperature cooling loop;

FIG. 6 schematically depicts another prior art cooling module for a vehicle having a low temperature cooling loop and a high temperature cooling loop;

FIG. 7 schematically depicts a cooling module for a vehicle having a low temperature cooling loop and a high temperature cooling loop according to an embodiment disclosed herein;

FIG. 8 is a cross-sectional view of two tubes suitable for use with embodiment(s) of the cooling module disclosed herein;

FIG. 9 is a semi-schematic view of a combo cooler according to embodiment(s) disclosed herein;

FIG. 10 schematically depicts another embodiment of a cooling module for a vehicle having a low temperature cooling loop and a high temperature cooling loop; and

FIG. 11 is a fluid flow diagram for a known oil cooler.

DETAILED DESCRIPTION

Embodiment(s) of the present disclosure relate to a cooling module for a vehicle having a high temperature cooling loop, cooling an internal combustion engine of a powertrain system of a vehicle, and a low temperature cooling loop, cooling at least an other component of the vehicle. Alternate embodiment(s) of the present disclosure relate to a cooling module for a hybrid electric vehicle.
An example of a traditional engine cooling module 10 for a vehicle powered by an internal combustion engine 11 is schematically depicted in FIG. 1. The engine cooling module 10 very generally includes a heat rejecter 12, 12′ and a high temperature radiator 14, both of which are operatively associated with the internal combustion engine 11. The heat rejecter 12, 12′ is configured to be used by an air conditioning system of the vehicle (not shown), where such air conditioning system includes an air conditioning loop for cooling, e.g., an internal cabin area of the vehicle. Examples of air conditioning loops are depicted by reference numerals 16, and 16′ in FIGS. 2 and 2A. It is to be understood that an air conditioning heat rejecter 12, 12′ may be a condenser 12 as depicted in FIG. 2, or a gas heat exchanger 12′ as depicted in FIG. 2A. The radiator 14 is configured to be used for cooling the internal combustion engine 11 (also referred to herein as the process of engine cooling) and may be used in an engine cooling loop. An example of the engine cooling loop for use in internal combustion engines (such as the engine 11) is depicted by reference number 18 in FIG. 3.
Referring now to an example of a vapor cycle air conditioning loop 16 depicted in FIG. 2, inside an evaporator 20, a refrigerant (generally represented by reference character R) increases in temperature and vaporizes as it removes excessive heat from, e.g., an internal cabin area of the vehicle. The vaporized refrigerant (represented by reference character R_v) is pressurized via a compressor 22 and is then introduced into the condenser 12. Inside the condenser 12, the refrigerant R_vis condensed into a liquid, the process of which causes the refrigerant R_vto release heat until it cools to its saturation temperature. The now liquidized refrigerant (represented by reference character R_L) passes through an expansion valve 24, where the refrigerant R_Lis depressurized, and flows back to the evaporator 20. Upon reaching the evaporator 20, another cycle of the vapor cycle air conditioning loop 16 begins.
Referring now to FIG. 2A, a gas cycle air conditioning loop 16′ may include a gas cycle refrigeration system. The components of a gas refrigeration cycle are similar to the vapor compression cycle refrigeration system discussed above. A refrigerant gas R is compressed by a compressor 22 causing a pressure and temperature of the refrigerant gas R to increase. Following compression, the refrigerant gas R is passed through a gas heat exchanger 12′, which functions similarly to the condenser 12 in the vapor compression cycle refrigeration system shown in FIG. 2, except there is no phase change of the refrigerant gas R. In the gas heat exchanger 12′, the refrigerant gas gives up heat, but its pressure remains substantially constant. The high pressure, medium temperature refrigerant gas R then enters a throttling valve 26′ where the pressure is suddenly reduced and the refrigerant gas R temperature becomes very low. The low temperature refrigerant gas R enters a heat exchanger also known as a refrigerator 20′ that performs a function similar to the evaporator 20 in the vapor compression system. The refrigerant gas absorbs heat from the substance to be cooled (for example, air in a vehicle passenger compartment). There is no change in phase of the refrigerant gas R in the refrigerator 20′. The refrigerant gas R then enters the compressor 22, and the cycle repeats.
The refrigerant R may be selected from a number of suitable refrigerants for use in a variety of air conditioning systems. A non-limiting example of a suitable refrigerant R for use in the vapor cycle air conditioning loop 16 includes R-134a. It is to be understood, however, that other fluids may also work such as, e.g., R-12 (DuPont Freon) or the like, which may be desirable for older vehicles, e.g., for those built prior to 1993. In an embodiment, carbon dioxide may be a refrigerant gas R for a gas cycle air conditioning system.
Referring to the example of the internal combustion engine cooling loop 18 depicted in FIG. 3, a coolant (represented by reference character C) that is heated by the internal combustion engine 11 flows into the high temperature radiator 14. By way of non-limitative example, internal combustion engine coolant may include liquid mixtures and solutions including antifreeze/anti-boil agents like ethylene glycol, propylene glycol, organic acid technology antifreeze, and hybrid organic acid technology antifreeze, which may be mixed with water, corrosion inhibitors and other additives like coloring agents. The radiator 14 transfers the heat from the coolant C-H to the ambient environment as the coolant C-H passes through the radiator 14. The cooled coolant C-H leaves the radiator 14 and is then introduced back into the internal combustion engine 11 to absorb more heat therefrom. Upon reaching the engine 11, another cycle of the engine cooling loop 18 begins.
Hybrid powertrains differ from internal combustion engine powertrains in that hybrid powertrains use both an internal combustion engine (e.g., the engine 11) and an electric motor (identified by reference numeral 32 in FIG. 5) to power a vehicle. In many instances, both the internal combustion engine 11 and the electric motor 32 are cooled using the same coolant. However, since the operating temperature of the internal combustion engine 11 and the electric motor 32 are significantly different, cooling of each is typically accomplished using two separate cooling loops; one to cool the internal combustion engine 11 and another to cool the electric motor 32.
It is to be understood that “operating temperature” means the normal temperature after the engine or other cooled component has warmed up, and the temperature has stabilized. Often, airflow and coolant flow are controlled to keep the temperature of the coolant within a desirable range. If separate cooling loops are used, it is possible to have different operating temperatures for each cooling loop.
An example of an engine cooling module 10′ currently used for a hybrid electric vehicle is schematically depicted in FIG. 4. The engine cooling module 10′ for a hybrid electric vehicle includes the heat rejecter 12, 12′ disposed between a low temperature radiator 30 (used in a low temperature cooling loop 28 depicted in FIG. 5) and the high temperature radiator 14 (used in the internal combustion engine cooling loop 18 depicted in FIG. 3, and is referred to herein as a high temperature cooling loop). Details of the internal combustion engine cooling loop 18 using the high temperature radiator 14 is described above in conjunction with FIG. 3.
The low temperature cooling loop 28 using the low temperature radiator 30 is shown in FIG. 5. As shown, the coolant C-L absorbs heat from for example, the electric motor 32, or a charge air cooler 32′, thereby raising the temperature of the coolant C-L. Thereafter, the coolant C-L leaves the electric motor 32 or the charge air cooler 32′ and enters the low temperature radiator 30, where the heat from the coolant C-L is transferred to the air flowing therethrough. Thus, the coolant C-L temperature is reduced, and the temperature of the air flowing therethrough is increased. The cooled coolant C-L then flows back to the electric motor 32 or the charge air cooler 32′, where the coolant C-L absorbs more heat. Upon reaching the electric motor 32 or the charge air cooler 32′, another cycle of the low temperature cooling loop 28 begins.
Referring now to FIG. 4, the engine cooling module 10′ includes the low temperature radiator 30 located upstream (with respect to airflow) of the heat rejecter 12, 12′ and the high temperature radiator 14. Such a configuration is used, at least in part, because of the constraints of the second law of thermodynamics, which provides that heat cannot spontaneously flow from a material at lower temperature to a material at higher temperature. Correlatively, all else being equal, a heat exchanger can transfer more heat when there is a greater temperature difference between a heat source (e.g. the radiator) and a heat sink (e.g. the air). More specifically, the temperature of the coolant C-L flowing through the low temperature radiator 30 is lower than that of the refrigerant R flowing through the heat rejecter 12,12′, and the temperature of the refrigerant R flowing through the heat rejecter 12,12′ is lower than that of the coolant C-H flowing through the high temperature radiator 14. It is to be understood that air flowing through the radiator or heat rejecter may, in the limit, approach the temperature of the respective coolant or refrigerant in the radiator or heat rejecter as the air exits the radiator or heat rejecter. In some instances, however, the temperature of the coolant C-L flowing through the low temperature radiator 30 may be about the same as that of the refrigerant R flowing through the heat rejecter 12, 12′. In such instances, the temperature difference between the air leaving the low temperature radiator 30 and that of the refrigerant R in the heat rejecter 12, 12′ tends to be very small. Such a small temperature difference may deleteriously affect cooling of the heat rejecter 12, 12′. To compensate, the heat rejecter 12, 12′ may be operated at an increased temperature, but such a compensatory measure may decrease the heat transfer available to a downstream high temperature radiator 14.
Other known engine cooling modules combine the low temperature radiator 30 and the high temperature radiator 14 into a single unit (such as the cooling module 10″ depicted in FIG. 6). As shown in the cooling module 10″ depicted in FIG. 6, the low and high temperature radiators 30, 14 are arranged so that their respective radiator tubes (not shown) lie in the same plane. In other words, the high temperature radiator 14 is placed on top of the low temperature radiator 30 (or visa versa) so that the radiators 14, 30 share the same frontal side or region. In this configuration, the radiators 14, 30 share the same inlet stream of ambient air. However, in instances where the combined radiator unit is placed downstream of the heat rejecter 12, 12′ (as shown in FIG. 6), the temperature of the air entering the low temperature radiator 30 may be undesirably higher than the temperature of the coolant C-L flowing therethrough, thereby deleteriously affecting cooling of the low temperature radiator 30.
The inventor of the present disclosure has unexpectedly and fortuitously discovered that combining the heat rejecter 12, 12′ and the low temperature radiator 30 into a single unit and placing the unit upstream of the high temperature radiator 14 advantageously provides a relatively compact, yet efficient cooling module for a vehicle without the problems associated with traditional modules as identified above. Embodiment(s) of the present disclosure may be particularly advantageous in a hybrid electric vehicle. Without being bound to any theory, it is believed that the foregoing advantages may be accomplished by arranging the heat exchangers of the cooling module (i.e., the low temperature radiator 30, the high temperature radiator 14, and the heat rejecter 12, 12′) so that the heat exchanger(s) operating at a higher temperature is/are located downstream from the heat exchanger(s) operating at a lower temperature.
Embodiments of a cooling module 10′″ and 10″″ according to the present disclosure are schematically depicted in FIGS. 7 through 10. In each of these embodiments, the cooling module 10′″, 10″″ includes a combo cooler 34, 34′, respectively, operatively associated with a vehicle (not shown in the figures). As used herein, the term “combo cooler” refers to a cooler having more than one heat exchanger, each heat exchanger cooling a different fluid and sharing the same frontal side or region enabling the heat exchangers to share the same inlet stream of air in parallel.
An embodiment of the cooling module 10′″ is depicted in FIGS. 7 and 9, whereby the combo cooler 34 includes a low temperature radiator 30 and a heat rejecter 12, 12′ arranged into a single unit. Another embodiment of the cooling module 10′∝ is depicted in FIG. 10, whereby the cooling module 10″″ includes a combo cooler 34′ having an oil cooler 35, a low temperature radiator 30, and a heat rejecter 12, 12′. In the combo cooler 34, 34′, the heat rejecter 12, 12′ and the low temperature radiator 30 are used in the air conditioning loop 16, 16′ and the internal combustion engine cooling loop 28, respectively, as described above in conjunction with FIGS. 2, 2A, and 5. The oil cooler 35, which has an oil flowing therethrough, is configured to cool lubrication oil, transmission fluid, power steering fluid, or other automotive lubricants and automotive hydraulic fluids where cooling may be desirable.
FIG. 11 depicts an oil cooler cooling loop 58. Automotive lubricant O absorbs heat from the internal combustion engine 11, and carries the heat through tubes (not shown) to oil cooler 35, wherein the automotive lubricant O is cooled. The cooled automotive lubricant O is circulated back to the internal combustion engine and begins another pass through the oil cooler cooling loop 58. It is to be understood that any powertrain component that requires automotive lubricant or hydraulic fluid cooling may be used instead of, or in conjunction with the internal combustion engine 11. Non limiting examples of such components include automatic transmissions and power steering pumps (not shown).
In either of the embodiments depicted in FIGS. 7 and 10, the heat exchangers of the combo coolers 34, 34′ share the same frontal side (identified by reference character F in FIGS. 7 and 10) and are therefore capable of receiving the same inlet ambient air stream in parallel. As also shown in FIGS. 7 and 10, the combo cooler 34, 34′ is located upstream of the high temperature radiator 14.
During operation of the cooling module 10′″ (depicted in FIG. 7), the operating temperature of the refrigerant flowing through the heat rejecter 12, 12′ and the coolant flowing through the low temperature radiator 30, are lower than the operating temperature of the coolant flowing through the high temperature radiator 14. Likewise, during operation of the cooling module 10″″ (depicted in FIG. 10), the operating temperatures of the oil flowing through the oil cooler 35, the refrigerant flowing through the heat rejecter 12, 12′, and the coolant flowing through the low temperature radiator 30 are lower than the temperature of the coolant flowing through the high temperature radiator 14. The foregoing configurations enable the high temperature radiator 14 to operate substantially efficiently as the cooler air exiting the combo cooler 34, 34′ travels over the high temperature radiator 14. Thus, the high temperature radiator 14 is capable of dissipating heat into the air stream.
Further details of the embodiment of the cooling module 10′″ are shown in FIG. 9. The heat rejecter 12, 12′ portion of the combo cooler 34 includes a plurality of heat rejecter tubes (an example heat rejecter tube 36 cross section is shown in FIG. 8) arranged in a substantially planar configuration. In a non-limiting example, the heat rejecter tubes 36 are extruded and are silicon particle coated or clad with a metal alloy for improved brazing. The low temperature radiator 30 also includes a plurality of low temperature radiator tubes (an example radiator tube 38 cross section is also shown in FIG. 8) which are also arranged in a substantially planar configuration. In a non-limiting example, the radiator tubes 38 may be electro-welded together and, thus, have electro-welded seams (not shown). In another non-limiting example, the radiator tubes 38 may be folded and subsequently brazed. The brazing could occur, for example, together with the combo cooler 34 as a whole. In instances where the radiator tubes 38 are subsequently brazed, the radiator tubes 38 may be clad at least on their exterior surfaces to improve brazing. At least one fin 40 is disposed between each heat rejecter tube 36 and/or each low temperature radiator tube 38. In a non-limiting example, the fin(s) 40 is/are non-clad fin(s).
The combo cooler 34 further includes a manifold 41 opposed to and substantially parallel to an other manifold 41′. The manifolds 41, 41′ are also each operatively connected to the heat rejecter tubes 36 and the low temperature radiator tubes 38. In a non-limiting example, the manifolds 41, 41′ are also independently configured to supply the refrigerant R to the heat rejecter 12,12′ and the coolant C-L to the low temperature radiator 30. As shown in FIG. 9, the refrigerant R flows into the heat rejecter 12, 12′ through inlet port 42, through the heat rejecter tubes 36, and out of the heat rejecter 12, 12′ through an exit port 44. Likewise, the coolant C-L flows into the low temperature radiator 30 through an inlet port 46, through the radiator tubes 38, and out of the radiator 30 through an exit port 48. The manifold 41 and the other manifold 41′ may each include at least one baffle 50 operatively disposed therein. The at least one baffle 50 is configured as a barrier between a fluid within the heat rejecter 12, 12′ and a fluid within the low temperature radiator 30. In an embodiment, the at least one baffle 50 prevents fluid communication between the refrigerant R and the coolant C-L.
It is to be understood that the term “internal combustion engine” may include any type of internal combustion engine. Non-limiting examples of internal combustion engines are compression ignition engines, spark ignition engines, and gas turbine engines, wherein any type of fuel is combusted. Non-limiting examples of fuels include gasoline, diesel fuel, biodiesel fuel, ethanol, methanol, kerosene, propane, methane, natural gas, hydrogen, and combinations thereof. The internal combustion engines may be naturally aspirated, turbo charged, super charged, and combinations thereof. It is to be further understood that the present disclosure is not limited by the type of fuel delivery system used in the internal combustion engine, including port injection, rail injection, direct injection, carburetion and the like.
While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.

Claims

1. A cooling module for a vehicle, comprising:

a combo cooler operatively associated with a vehicle, including:

a heat rejecter having a plurality of heat rejecter tubes operatively connected thereto, the plurality of heat rejecter tubes arranged in a substantially planar configuration;

a low temperature radiator operatively associated with the heat rejecter and in fluid communication with a low temperature cooling loop of the vehicle, the low temperature radiator having a plurality of low temperature radiator tubes operatively connected thereto and arranged in a substantially planar configuration;

a manifold opposed to and substantially parallel to an other manifold, the manifold and the other manifold each operatively connected to the plurality of heat rejecter tubes and the plurality of low temperature radiator tubes, the manifold and the other manifold also independently configured to supply a refrigerant to the heat rejecter and a coolant to the low temperature radiator; and

at least one fin disposed between each one of the plurality of the heat rejecter tubes and the plurality of the low temperature radiator tubes; and

a high temperature radiator disposed adjacent and substantially parallel to the combo cooler, and downstream of the combo cooler relative to an air stream flowing through the combo cooler and the high temperature radiator, the high temperature radiator operatively associated with a high temperature cooling loop of the vehicle and configured to cool an other coolant flowing therethrough;

wherein an operating temperature of the refrigerant in the heat rejecter and an operating temperature of the coolant in the low temperature radiator of the combo cooler are lower than an operating temperature of the other coolant in the high temperature radiator.

2. The cooling module as defined in claim 1 wherein the vehicle is a hybrid electric vehicle, the low temperature cooling loop is an electric motor cooling loop, and the high temperature cooling loop is an internal combustion engine cooling loop.

3. The cooling module as defined in claim 1 wherein the high temperature cooling loop is an internal combustion engine cooling loop, and the low temperature cooling loop is a charge air cooler cooling loop.

4. The cooling module as defined in claim 1 wherein the heat rejecter is a condenser operatively associated with a vapor cycle refrigeration system.

5. The cooling module as defined in claim 4 wherein the refrigerant is R134a or R12.

6. The cooling module as defined in claim 1 wherein the heat rejecter is a gas heat exchanger operatively associated with a gas cycle refrigeration system.

7. The cooling module as defined in claim 6 wherein the refrigerant is carbon dioxide gas.

8. The cooling module as defined in claim 1 wherein each of the plurality of heat rejecter tubes is extruded and silicon particle coated.

9. The cooling module as defined in claim 1 wherein each of the plurality of heat rejecter tubes is extruded and clad with a metal alloy.

10. The cooling module as defined in claim 1 wherein each of the plurality of the low temperature radiator tubes is individually folded and subsequently brazed with the combo cooler as a whole.

11. A cooling module for a vehicle, comprising:

a combo cooler, including:

an oil cooler operatively associated with the heat rejecter and the low temperature radiator, the oil cooler having at least one oil cooler tube operatively connected thereto and also arranged in a substantially planar configuration;

a manifold opposed to and substantially parallel to an other manifold, the manifold and the other manifold each operatively connected to the plurality of heat rejecter tubes, the plurality of low temperature radiator tubes, and the at least one oil cooler tube, the manifold and the other manifold also independently configured to supply a refrigerant to the heat rejecter, a coolant to the low temperature radiator, and an oil to the oil cooler; and

at least one fin disposed between i) the at least one oil cooler tube, and ii) each of the plurality of the heat rejecter tubes and the plurality of the low temperature radiator tubes; and

a high temperature radiator disposed adjacent and substantially parallel to the combo cooler, and downstream of the combo cooler relative to an air stream flowing through the combo cooler and the high temperature radiator, the high temperature radiator configured to cool an other coolant flowing therethrough;

wherein an operating temperature of the refrigerant in the heat rejecter, an operating temperature of the oil in the oil cooler, and an operating temperature of the coolant in the low temperature radiator of the combo cooler are lower than an operating temperature of the other coolant in the high temperature radiator.

12. The cooling module as defined in claim 11 wherein the vehicle is a hybrid electric vehicle, the low temperature cooling loop is an electric motor cooling loop, and the high temperature cooling loop is an internal combustion engine cooling loop.

13. The cooling module as defined in claim 11 wherein the high temperature cooling loop is an internal combustion engine cooling loop, and the low temperature cooling loop is a charge air cooler cooling loop.

14. The cooling module as defined in claim 11 wherein the heat rejecter is a condenser operatively associated with a vapor cycle refrigeration system.

15. The cooling module as defined in claim 14 wherein the refrigerant is R134a or R12.

16. The cooling module as defined in claim 11 wherein the heat rejecter is a gas heat exchanger operatively associated with a gas cycle refrigeration system.

17. The cooling module as defined in claim 16 wherein the refrigerant is carbon dioxide gas.

18. The cooling module as defined in claim 11 wherein each of the plurality of heat rejecter tubes is extruded and silicon particle coated.

19. The cooling module as defined in claim 11 wherein each of the plurality of heat rejecter tubes is extruded and clad with a metal alloy.

20. The cooling module as defined in claim 11 wherein each of the plurality of low temperature radiator tubes is folded and subsequently brazed with the combo cooler as a whole.