Title:
Cooling system with expansion driven fan
Kind Code:
A1


Abstract:
A cooling system for cooling a flow of fluid from a heat source includes a turbine configured to be fluidly connected to the heat source. The turbine is configured to receive the flow of fluid from the heat source. The cooling system also includes a fan configured to be driven by the turbine. The fan includes at least one channel for receiving the flow of fluid from the turbine.



Inventors:
Campagna, Michael Joseph (Chillicothe, IL, US)
Callas, James John (Peoria, IL, US)
Martin, Kevin Lee (Washburn, IL, US)
Application Number:
11/797015
Publication Date:
10/30/2008
Filing Date:
04/30/2007
Assignee:
Caterpillar Inc.
Primary Class:
International Classes:
F25D9/00
View Patent Images:
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Primary Examiner:
KAMEN, NOAH P
Attorney, Agent or Firm:
CATERPILLAR/FINNEGAN, HENDERSON, L.L.P. (WASHINGTON, DC, US)
Claims:
What is claimed is:

1. A cooling system for cooling a flow of fluid from a heat source, the cooling system comprising: a turbine configured to be fluidly connected to the heat source, the turbine being configured to receive the flow of fluid from the heat source; and a fan configured to be driven by the turbine, the fan including at least one channel for receiving the flow of fluid from the turbine.

2. The cooling system of claim 1, wherein the fan is configured to direct the flow of fluid to the heat source.

3. The cooling system of claim 1, wherein the fan includes a plurality of fan blades and a plurality of the channels, and each of the fan blades includes at least one of the channels.

4. The cooling system of claim 3, wherein the channels are microchannels.

5. The cooling system of claim 1, further including a fan shroud surrounding a plurality of fan blades of the fan, the fan shroud including a reservoir configured to receive the flow of fluid from the at least one channel of the fan.

6. The cooling system of claim 1, further including a heat exchanger, the heat exchanger being configured to receive the flow of fluid from the fan, the fan being configured to direct a flow of air through the heat exchanger.

7. The cooling system of claim 1, further including an evaporator configured to receive the flow of fluid from the fan and to direct the flow of fluid to the heat source.

8. The cooling system of claim 1, wherein: the turbine is a two-phase turbine; the flow of fluid received by the turbine is a mixture of gas and liquid; the turbine is configured to convert the mixture of gas and liquid to a substantially liquid flow; and the flow of fluid received by the at least one channel in the fan is the substantially liquid flow.

9. A method of cooling a flow of fluid from a heat source, comprising: directing the flow of fluid from the heat source to a turbine; transferring rotational motion from the turbine to a fan; and directing the flow of fluid from the turbine to at least one channel in the fan.

10. The method of claim 9, further including directing the flow of fluid from the at least one channel in the fan to the heat source.

11. The method of claim 9, wherein the fan includes a plurality of fan blades and a plurality of the channels, and each of the fan blades includes at least one of the channels.

12. The method of claim 11, wherein the directing of the flow of fluid from the at least one channel in the fan to the heat source includes directing the flow of fluid to a reservoir in a fan shroud surrounding the fan blades.

13. An engine and a cooling system for cooling a fluid flow from the engine, the cooling system comprising: a two-phase turbine fluidly connected to the engine, the turbine being configured to receive the fluid flow in the form of a mixture of liquid and gas from the engine and output the fluid flow in the form of a substantially liquid flow; and a fan configured to be driven by the turbine.

14. The engine and the cooling system of claim 13, wherein the fan is configured to receive the substantially liquid flow from the turbine and direct the substantially liquid flow to the engine.

15. The engine and the cooling system of claim 14, wherein the fan includes a plurality of fan blades, and the substantially liquid flow passes through a plurality of channels in the fan blades.

16. The engine and the cooling system of claim 15, wherein the fan is configured to direct the substantially liquid flow to a reservoir in a fan shroud encircling the fan blades, and the fan shroud is configured to direct the substantially liquid flow to the engine.

17. The engine and the cooling system of claim 13, wherein a majority of the mixture of gas and liquid is gas.

18. The engine and the cooling system of claim 13, wherein the engine includes an engine block with at least one cavity cast into the engine block.

19. The engine and the cooling system of claim 18, further including at least one heat exchanger disposed inside the at least one cavity in the engine block, the at least one heat exchanger being configured to receive the substantially liquid flow from the turbine.

20. The engine and the cooling system of claim 19, wherein the heat exchanger disposed inside the at least one cavity includes a plurality of microchannels.

21. The engine and the cooling system of claim 19, further including an evaporator configured to receive the substantially liquid flow from the turbine and direct the substantially liquid flow to the at least one heat exchanger disposed in the engine block.

22. The engine and the cooling system of claim 21, wherein: the substantially liquid flow is directed from the turbine to a plurality of channels in a plurality of fan blades of the fan; the substantially liquid flow is directed from the plurality of channels in the plurality of fan blades to a reservoir in a fan shroud surrounding the fan; and the substantially liquid flow is directed from the reservoir to the evaporator.

Description:

TECHNICAL FIELD

The present disclosure relates generally to a cooling system, and more particularly, to a cooling system with an expansion driven fan.

BACKGROUND

Machines, such as on-highway vehicles and off-highway machines of a wide variety, may be powered by various types of engines, such as internal combustion engines. Internal combustion engines, the various systems associated with internal combustion engines in machines, and other components of a machine require a cooling system to dissipate heat. The size of a cooling system may vary based on a number of factors, including the amount of heat generated by the engine and its associated systems, and other machine components.

The components of the cooling system may be located at the frontal area of the truck or other machine. For example, the cooling system may be designed to be accommodated at the frontal area of a machine. The cooling system may include components for cooling hydraulic oil, engine coolant, and engine charge air. The cooling system may also include one or more air movers, such as one or more fans, which may assist the dissipation of heat from the various components of the cooling system.

Furthermore, environmental and economic concerns dictate that measures be taken to reduce pollution by the byproducts of combustion in internal combustion engines and to improve fuel economy. In recent years, for example, emphasis has been placed on reducing the emission of oxides of nitrogen (NOx) and particulates, in addition to improving fuel economy. Various systems and devices may be provided to reduce undesirable emissions to the environment. However, these systems and devices tend to generate more heat that needs to be dissipated and thus an increase of the cooling system load. Therefore, there is a need to provide increased cooling while minimizing the space required for the cooling system in order to allow more space for the emissions reduction systems and devices.

One type of cooling system is described in U.S. Pat. No. 5,090,371 (the '371 patent) issued to Schäpertöns et al. The '371 patent describes a cooling system that directs exhaust gas from an internal combustion engine through a heat exchanger, which heats the exhaust gas to generate steam. Then, the steam is directed to a turbine, and the steam drives the turbine, which in turn drives a fan and a pump. The steam is then directed to a condenser that is cooled by the fan, and the steam condenses into a liquid. The liquid is then directed, via a pump, to cooling chambers and conduits of the engine.

Although the cooling system of the '371 patent provides a cooling system for cooling the exhaust gas of an engine, the cooling system cools the exhaust gas with the condenser, which is cooled by a flow of air from the cooling fan. However, the cooling fan is limited in its ability to cool the exhaust gas. Therefore, in machines that use more power, more heat is generated by the engine, and a larger condenser and cooling fan are used to more adequately cool the exhaust gas. More power may be necessary to operate the cooling system, and fuel consumption may be increased.

The disclosed system is directed to overcoming one or more of the problems set forth above.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure is directed to a cooling system for cooling a flow of fluid from a heat source. The cooling system includes a turbine configured to be fluidly connected to the heat source. The turbine is configured to receive the flow of fluid from the heat source. The cooling system also includes a fan configured to be driven by the turbine. The fan includes at least one channel for receiving the flow of fluid from the turbine.

In another aspect, the present disclosure is directed to a method of cooling a flow of fluid from a heat source. The method includes directing the flow of fluid from the heat source to a turbine, transferring rotational motion from the turbine to a fan, and directing the flow of fluid from the turbine to at least one channel in the fan.

In a further aspect, the present disclosure is directed to an engine and a cooling system for cooling a fluid flow from the engine. The cooling system includes a two-phase turbine fluidly connected to the engine. The turbine is configured to receive the fluid flow in the form of a mixture of liquid and gas from the engine and output the fluid flow in the form of a substantially liquid flow. The cooling system also includes a fan configured to be driven by the turbine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an engine and a cooling system according to an exemplary embodiment;

FIG. 2 is a plan view of a cooling fan of the cooling system of FIG. 1 according to an exemplary embodiment;

FIGS. 3A-3C are cross-sectional views of a fan blade of the cooling fan of FIG. 2 according to exemplary embodiments;

FIG. 4 is a plan view of a fan shroud of the cooling system of FIG. 1 according to an exemplary embodiment;

FIG. 5 is a cross-sectional view of the fan shroud and the cooling fan of FIG. 1 according to an exemplary embodiment; and

FIG. 6 is a schematic illustration of an engine and a cooling system according to another exemplary embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

As shown in FIG. 1, a heat source, such as an engine 10 or other power source, of a machine is provided. The disclosed embodiment may be applicable to various types of machines such as, for example, a fixed or mobile machine that performs some type of operation associated with an industry such as mining, construction, farming, transportation, power generation, tree harvesting, forestry, or any other industry known in the art. For example, the machine may be an on-highway or off-highway truck, crane, earthmoving machine, mining vehicle, material handling equipment, farming equipment, marine vessel, aircraft, an excavator, a dozer, a loader, a backhoe, a motor grader, a dump truck, a turbine, a power production system, an engine system operating in a plant or an off-shore environment, a feller, a harvesting machine, a skidder, a forwarder, a drag line system, or any type of machine that operates in a work environment such as a construction site, mine site, power plant, tree harvesting site, etc.

The engine 10 may be, for example, an internal combustion engine of the diesel, gasoline, or gaseous fuel-driven type, or any other type of engine. The power source may alternatively include another source of power such as a furnace or any other suitable source of power. The engine 10 may include a coolant circulating system (not shown) that includes, e.g., one or more cooling chambers and/or conduits in and/or adjacent to the engine 10. The coolant may be, e.g., water, oil, or other fluid. According to one embodiment, the coolant circulating system may be a jacket water cooler that circulates water to cool, e.g., engine oil, hydraulic oil, intake air, an engine block 12, engine cylinders, etc.

The engine 10 is fluidly connected to a cooling system 20. The cooling system 20 may be located separately from the engine 10 and anywhere in the machine. According to one embodiment, the cooling system 20 may be located near the engine 10 at the front of the machine. The cooling system 20 is configured to cool the coolant circulating in the engine 10. The cooling system 20 may include one or more heat exchangers, turbines, pumps, fans, etc., connected by fluid passageways. According to the exemplary embodiment shown in FIG. 1, the cooling system 20 includes fluid passageways 22, 26, 28, a throttle valve 24, a turbine 30, a cooling fan 40, a fan shroud 50, a pump 60, and a radiator 70.

A first fluid passageway 22 fluidly connects the engine 10 to the turbine 30 and allows the coolant from the engine 10 to flow to the turbine 30. The throttle valve 24 or other throttling device may be located in the first fluid passageway 22 downstream from the engine 10 and upstream from the turbine 30. The throttle valve 24 may be configured to selectively restrict the flow of coolant to the turbine 30. A restrictive setting of the throttle valve 24 limits the flow rate and/or pressure of coolant entering the turbine 30.

The turbine 30 is configured to drive the cooling fan 40. For example, as shown in FIGS. 1 and 6, the turbine may be fixed or attached to the cooling fan 40 in order to rotate with and drive the cooling fan 40. Alternatively, the turbine 30 and the cooling fan 40 may be connected by a shaft so that the turbine 30 may drive the cooling fan 40. The turbine 30 may also be configured to drive other components of the engine 10 and/or the cooling system 20, such as the pump 60. According to an embodiment, the turbine 30 may be a two-phase turbine including an inlet 32 that is capable of receiving a mixture of liquid and gas. The two-phase turbine 30 extracts energy from the liquid-gas mixture and condenses at least a portion of the gas in the liquid-gas mixture into a liquid. The energy extracted from the liquid-gas mixture is transformed into mechanical work, e.g., rotation of the turbine 30. The turbine 30 is configured to transfer the rotational motion to the cooling fan 40. The cooling fan 40 is positioned adjacent to the radiator 70 such that a plurality of fan blades 42 of the cooling fan 40 may drive or draw air through the tubes of the radiator 70.

The turbine 30 includes an outlet 34 through which the flow of coolant passes. The turbine outlet 34 is fluidly connected to a plurality of channels 44 in the fan blades 42 of the cooling fan 40. Each fan blade 42 includes at least one channel 44. For example, each fan blade 42 may include a single channel 44. Alternatively, each fan blade 42 may include a plurality of channels 44 arranged as shown in FIGS. 3A-3C. In addition to the embodiments shown in FIGS. 3A-3C, it is to be understood that the plurality of channels may be arranged in other ways, e.g., tubes and passageways of other geometric shapes, such as circles, triangles, rectangles, hexagons, etc. According to an embodiment, the channels 44 may be microchannels, i.e., having at least one dimension in the sub-micrometer or multi-micrometer range. Alternatively, the channels 44 may have a larger cross-sectional area. Alternatively, instead of providing channels 44, the fan blades 42 may be formed with a solid outer housing filled with foam or other porous material. Each of the fan blades 42 may be formed of a rigid material, such as plastic or metal, e.g., aluminum or nickel or other electroplated material. Electroplating and similar processes may allow the channels 44 to be formed with smaller cross-sectional area, thereby allowing a greater number of channels 44 in a single fan blade 42 and increasing the ability to cool the coolant flowing through the channels 44.

The cooling fan 40 is an air-to-liquid heat exchanger. As the cooling fan 40 is driven by the turbine 30, a flow of ambient air (indicated by arrows A in FIG. 1) may flow over the exterior surfaces of the fan blades 42 and between the fan blades 42 of the cooling fan 40, thereby removing some of the heat from the coolant that is flowing through the channels 44 in the fan blades 42.

As shown in FIG. 2, the cooling fan 40 may be shaped like a spoked wheel with the turbine 30 as a hub, the plurality of fan blades 42 as spokes, and a ring 46 as the wheel. An outer portion of each fan blade 42 connects to the ring 46 such that the ring 46 encircles all of the fan blades 42. The ring 46 may be formed such that the coolant from the channels 44 may pass therethrough, e.g., through openings in an outer edge 48 of the ring 46. For example, the channels 44 in the fan blades 42 may be fluidly connected to corresponding channels (not shown) in the ring 46 that extend to the outer edge 48 of the ring 46. Alternatively, the ring 46 may be formed with hollow portions (not shown) that extend to the outer edge 48 of the ring 46 and that allow the coolant from the channels 44 in the fan blades 42 to pass through the ring 46. Thus, each channel 44 in the fan blades 42 may receive coolant from the outlet 34 of the turbine 30, and the coolant may then pass through the channels 44 in the fan blades 42 and through the ring 46.

The fan shroud 50 is stationary and annular, as shown in FIG. 4, and may be formed of plastic, metal, or other rigid material, as known in the art. The fan shroud 50 surrounds the cooling fan 40 circumferentially. As shown in FIG. 5, the fan shroud 50 may encircle the ring 46 such that the ring 46 is disposed in an opening 54 of the fan shroud 50. Coolant from the channels 44 in the fan blades 42 may pass through the ring 46 in the cooling fan 40 and may flow into a reservoir 52 in the fan shroud 50. The depth of the reservoir 52 may vary and may be sized such that coolant received from the cooling fan 40 may be collected in the reservoir 52 or may pass through the reservoir 52.

As shown in FIGS. 4 and 5, the fan shroud 50 includes a pair of rims 56 along each side of the opening 54. The rims 56 extend into the reservoir 52 and provide a surface for attaching a pair of seals 58. The seals 58 provide a substantially fluid tight connection between the ring 46 of the cooling fan 40 and the rims 56 of the fan shroud 50. Alternatively, the seals 58 may be provided on the ring 46 of the cooling fan 40. Other types of seals between the cooling fan 40 and the fan shroud 50 may be provided, as is known in the art, e.g., a lip seal, a face seal, etc. The seals 58 may be made of plastic, rubber, polymer, composite, etc., as known in the art.

As shown in FIG. 1, the fan shroud 50 also includes an outlet 59 that allows coolant from the reservoir 52 to exit the fan shroud 50. The outlet 59 of the fan shroud 50 is fluidly connected via the second fluid passageway 26 to the pump 60. The pump 60, e.g., a water pump, is disposed in the second fluid passageway 26 downstream from the fan shroud 50 and upstream from the radiator 70. It is contemplated that the pump 60 may be omitted. Alternatively, the pump 60 may be disposed in the third fluid passageway 28 fluidly connecting the radiator 70 to the engine 10. According to an embodiment, the pump 60 may be driven by the turbine 30. The pump 60 may direct the coolant from the reservoir 52 in the fan shroud 50 to the radiator 70 for further cooling.

The radiator 70 or other heat exchanger may be fluidly connected to the second fluid passageway 26 downstream from the pump 60. The radiator 70 is an air-to-liquid heat exchanger that includes a plurality of tubes (not shown) configured to circulate the coolant received from the pump 60. The radiator 70 may be positioned near the cooling fan 40, and a flow of ambient air (indicated by arrows A in FIG. 1) may be drawn through the tubes of the radiator 70 by the cooling fan 40. The ambient air contacts an exterior surface of the coolant-carrying tubes of the radiator 70, and flows through spaces between the radiator tubes and across the radiator tubes, thereby removing some of the heat from the coolant that is flowing through the radiator tubes. It is contemplated that the radiator 70 may be omitted. An outlet of the radiator 70 is fluidly connected to the engine 10 via the third fluid passageway 28. After returning to the engine 10, the coolant may be recirculated through the coolant circulating system.

According to another exemplary embodiment as shown in FIG. 6, an evaporator 80 or other heat exchanger may be disposed in the third fluid passageway 28 downstream from the radiator 70 and upstream from the engine 10. According to the exemplary embodiment, the evaporator 80 is part of a refrigeration loop that also includes a compressor 84, a condenser 86, and a throttle valve 88, which are connected by refrigerant passageways 82. Refrigerant or other type of fluid is circulated through the refrigeration loop.

The refrigerant is transferred via the refrigerant passageway 82 to the evaporator 80 from the throttle valve 88, which regulates the flow rate and/or pressure of the refrigerant entering the evaporator 80. The refrigerant expands and changes to a gas inside the evaporator 80. This change of state cools the refrigerant in the evaporator 80. The refrigerant then cools the coolant passing through the evaporator 80. After cooling the coolant, the refrigerant is transported via refrigerant passageway 82 to the compressor 84. The compressor 84 compresses the refrigerant gas and outputs pressurized refrigerant that is sent to the condenser 86 via refrigerant passageway 82.

The condenser 86 is a heat exchanger that extracts some of the heat from the refrigerant and condenses the refrigerant gas to a high pressure liquid. The condensation requires heat to be rejected from the refrigerant gas. The condenser 86 may be an air-to-liquid heat exchanger. The condenser 86 includes a plurality of tubes (not shown) configured to circulate the refrigerant received from the compressor 84. The condenser 86 may be positioned near the cooling fan 40, and a flow of ambient air (indicated by arrows A in FIG. 6) may be drawn through the tubes of the condenser 86 by the cooling fan 40. The ambient air contacts an exterior surface of the refrigerant-carrying tubes of the condenser 86, and flows through spaces between the condenser tubes and across the condenser tubes, thereby removing some of the heat from the refrigerant flowing through the condenser tubes. The refrigerant is at least partly cooled in this manner and is then returned to the throttle valve 88 via refrigerant passageway 82 so that the refrigerant may be recirculated through the refrigeration loop.

The refrigerant in the evaporator 80 cools the coolant passing through the evaporator 80. The coolant exiting the evaporator 80 flows to the engine 10 via the third fluid passageway 28. In the engine 10, the coolant may be circulated through one or more coolers 90, 92, 94, which may be connected by fluid passageways 96, 98. Each cooler 90, 92, 94 may be disposed in respective cavities 12A, 12B, 12C in the engine block 12 of the engine 10. According to an embodiment, each cavity 12A, 12B, 12C may be cast directly into the engine block 12, and each cooler 90, 92, 94 may be an ultra-compact cooler including channels 99, such as microchannels, i.e., having at least one dimension in the sub-micrometer or multi-micrometer range.

The first engine cooler 90 may be an air-to-liquid heat exchanger that allows heat to be transferred to the coolant from one or more components of the engine 10, e.g., air used for combustion before entering an inlet manifold (not shown) of the engine 10. The coolant exiting the first engine cooler 90 may be directed via the fluid passageway 96 toward the second engine cooler 92.

The second engine cooler 92 may be an intercooler or other heat exchanger that allows heat to be transferred to the coolant from one or more components of the engine 10, e.g., compressed air from a low pressure compressor before being directed to a high pressure compressor. The coolant exiting the second engine cooler 92 may be directed via the fluid passageway 98 toward the third engine cooler 94.

The third engine cooler 94 may be a liquid-to-liquid heat exchanger that that allows heat to be transferred to the coolant from one or more components of the engine 10, e.g., the engine oil used in the engine 10. The coolant exiting the third engine cooler 94 may be directed via the first fluid passageway 22 out of the engine 10 and toward the throttle valve 24, and then recirculated through the cooling system 20 as described above in connection with FIG. 1.

INDUSTRIAL APPLICABILITY

The disclosed cooling system may be provided in any machine with one or more components that generate heat and may be used for a variety of applications. For example, the cooling system may be provided in a prime-mover, vehicle, or the like, or any type of machine requiring mechanical or electrical energy.

According to an exemplary embodiment, the coolant is water that circulates through a jacket water cooler in the engine 10. Heated water, e.g., superheated water (pressurized water with a temperature that is above the boiling point), may be sent from the engine 10 through the first fluid passageway 22 to the throttle valve 24. The throttle valve 24 may reduce the pressure of the superheated water and may flash at least a portion of the superheated water to steam. The first fluid passageway 22 then directs the steam or the mixture of steam and water from the throttle valve 24 to the turbine 30. In the exemplary embodiment, the turbine 30 is a two-phase turbine, which is capable of operating when it receives a mixture of liquid and gas, e.g., a mixture of steam and water. The steam expands against blades (not shown) of the turbine 30, and energy is extracted from the expansion of the steam. The extracted energy is directed toward rotating the turbine 30, and the turbine 30 rotates and drives the connected cooling fan 40. By allowing the steam to expand and by extracting the energy, at least a portion of the steam condenses to a flow of hot water. Thus, while a flow made up substantially of steam enters the turbine 30, a substantially or completely liquid flow, i.e., a flow of water, exits the turbine 30. It is to be understood, however, that the flow of water exiting the turbine 30 may contain some vapor. Thus, the turbine 30 extracts energy, which would otherwise be wasted, from the heated coolant flow from the engine 10. The turbine 30 uses the energy to drive the cooling fan 30 and optionally one or more components (e.g., a fan, an air compressor, a water pump, an alternator, a generator, belt-driven equipment, an air conditioner, etc.) of the engine 10. As a result, the cooling system 20 is able to reduce the parasitic loads on the engine 10. Fuel consumption may also be reduced.

The turbine 30 is fluidly connected to the cooling fan 40 such that the substantially liquid flow, i.e., the flow of water, exiting the turbine 30 flows into the channels 44 in the fan blades 42. The water flows through the fan blades 42 while the turbine 30 drives the cooling fan 40. As a result, heat from the water may be transferred to the surfaces of the fan blades 42 surrounding the channels 44 and to the surrounding atmosphere. Accordingly, the cooling fan 40 is an air-to-liquid (air-to-water) heat exchanger, and the water is at least partly cooled in this manner. In the exemplary embodiment, the channels 44 may be microchannels that allow for greater heat transfer from the water to the fan blades 42 and the surrounding atmosphere.

The rotating fan blades 42 of the cooling fan 40 drive or draw a flow of ambient air (indicated by arrows A in FIG. 1) toward the radiator 70 by the cooling fan 40. The flow of ambient air passes over the surfaces of each of the fan blades 42, including an exterior surfaces of the channels 44 in the fan blades 42. As a result, the water is at least partly cooled by the flow of ambient air passing over the outer surfaces of the fan blades 42. Accordingly, even more heat may be transferred from the water to the surrounding atmosphere.

The water may exit the channels 44 and the ring 46 of the fan blades 42 and may be directed to the reservoir 52 in the fan shroud 50. The water may then be directed through the reservoir outlet 59 to the pump 60 via the second fluid passageway 26. The pump 60 then directs the water from the second fluid passageway 26 to the radiator 70. The water received from the pump 60 may circulate through the tubes of the radiator 70. The flow of ambient air (indicated by arrows A in FIG. 1) drawn toward the radiator 70 from the cooling fan 40 allows the ambient air to contact an exterior surface of the radiator tubes that carry the water received from the reservoir 52. The water is at least partly cooled in this manner.

The radiator 70 may be of a smaller size than conventional radiators if sufficient cooling is provided by the other cooling devices in the cooling system 20 described above, e.g., the transfer of heat from the water to the surfaces of fan blades 42 surrounding the channels 44 and to the surrounding atmosphere, and the transfer of heat to the air passing over the fan blades 42 due to the rotation of the cooling fan 40. Alternatively, the radiator 70 may be omitted if additional cooling is unnecessary. As a result, the overall cooling system 20 size may be reduced while allowing an increase in net power and decrease in gross power provided by the engine 10. If the cooling system 20 is disposed in the frontal area of the machine, the machine operator may have improved sight lines when the cooling system 20 size is decreased. Also, costs of manufacturing, operating, and maintaining the machine may be reduced by omitting or reducing the size of the radiator 70.

The water from the radiator 70 may be transferred to the engine 10 through the third fluid passageway 28. Thus, the engine 10 outputs superheated water to the cooling system 20 and receives a flow of at least partially cooled water from the cooling system 20. The water may be recirculated through the jacket water cooler of the engine 10 to cool the components of the engine 10.

According to the exemplary embodiment shown in FIG. 6, water from the radiator 70 (or from the pump 60 if the radiator 70 is omitted) may be directed to the evaporator 80. The evaporator 80 is part of the refrigeration loop, which may cool the water passing through the evaporator 80 to below ambient temperature. As a result, cooled refrigerant passes through the evaporator 80 and cools the water received from the radiator 70. In this manner, the water is cooled even further to below ambient temperature before returning to the engine 10 via the third fluid passageway 28, thereby allowing the cooling system 20 to provide coolant at cooler temperatures.

Also, as shown in FIG. 6, the engine 10 may include one or more cavities 12A, 12B, 12C that are cast into the engine block 12. The engine coolers 90, 92, 94 may include a plurality of channels 99, e.g., the microchannels described above, to allow the cooled water passing through the channels 99 to efficiently cool the engine components, e.g., air used in combustion, engine oil, etc. Microchannels allow the engine coolers 90, 92, 94 to be smaller such that they may fit into the cavities 12A, 12B, 12C, cast into the engine block 12 while allowing for greater heat transfer from the water in the microchannels to the engine components.

The cooling system 20 provided in the exemplary embodiments may be a high pressure system that is capable of being operated with a higher pressure limit. Since there is a higher pressure limit, the engine 10 may reject more heat by supplying coolant at a higher pressure, e.g., pressurized superheated water, to the cooling system 20. The cooling system 20 is capable of receiving and operating with the coolant at the higher pressure. For example, the throttle valve 24 may reduce the pressure of the superheated water from the engine 10 so that the coolant is at least partially gaseous, and then the two-phase turbine 30 may convert the coolant back to a substantially or completely liquid flow. Then, the coolant is directed to the other components of the cooling system 20 and returned to the engine 10 where it becomes superheated water again. According to an exemplary embodiment, the pressure limit of the cooling system 20 may be greater than 15 pounds per square inch (psi), e.g., up to or approximately 40 psi.

When the coolant is at higher pressures, the temperature limit of the coolant (i.e., the coolant's boiling point) is higher. Higher coolant temperatures allow a larger temperature differential between the hot temperature of the coolant exiting the engine 10 and the temperature of the atmosphere. As a result, the engine 10 may reject a greater amount of heat via the coolant since the coolant is able to circulate and cool the components of the engine 10 that are at a much higher temperature without the coolant boiling. Thus, the cooling system 20 and the engine 10 may be characterized as a high temperature, high pressure loop that may include the turbine 30, the cooling fan 40, and the fan shroud 50, and optionally the throttle valve 24, the pump 60, the radiator 70, and the evaporator 80. Greater heat transfer may be achieved, thereby allowing an increased amount of heat to be rejected from the cooling system 20 without having to increase its size.

It will be apparent to those skilled in the art that various modifications and variations can be made to the cooling system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed cooling system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.