US20090000318A1

US20090000318A1 - Environmentally friendly heatpump system

Info

Publication number: US20090000318A1
Application number: US12/147,923
Authority: US
Inventors: Charles M. Hart
Original assignee: Individual
Current assignee: Parker Hannifin Corp
Priority date: 2007-06-27
Filing date: 2008-06-27
Publication date: 2009-01-01

Abstract

A heatpump system (10) for controlling the temperature of a fluid within a predetermined space (12). The heatpump system (10) comprises a heat-transferring component (14) located proximate to predetermined space (12) and a heat-transferring sink (26) located remote from the predetermined space (12). In the remote heat sink, heat is rejected to and/or absorbed from an environmentally contaminable medium (e.g., soil or water). The heatpump system (10) further comprises a naturally occurring refrigerant (e.g., carbon dioxide) that is carried through the cycle by a circuit (20).

Description

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. 119 (e) to U.S. Provisional Patent Application No. 60/946,413 filed on Jun. 27, 2007 and U.S. Provisional Patent Application No. 61/043,799 filed on Apr. 10, 2008. The entire disclosures of these provisional applications are hereby incorporated by reference. If incorporated-by-reference subject matter is inconsistent with subject matter expressly set forth in the written specification and drawings of this application, the present disclosure governs to the extent necessary to eliminate indefiniteness and/or clarity-lacking issues.

GENERAL FIELD

A heatpump system comprising a proximate heat-transferring component and a remote heat-transferring sink.

BACKGROUND

A heatpump system can be used to control the temperature of a fluid within a predetermined space, such as the air inside a building. When a heatpump system operates in a first (forward) direction, it cools the fluid. The refrigerant is evaporated within a heat-transfer component that is proximate to the to-be-cooled fluid (e.g., it is in or near the predetermined space). The evaporated refrigerant is compressed (e.g., by a compressor) and then conveyed to a heat-transfer location whereat heat can be rejected to a suitable sink and the refrigerant condensed. Usually, this sink is remote from the predetermined space, so that the rejected heat does not return to the to-be-cooled fluid.
When a heatpump system operates in a second (reverse) direction it heats the fluid within the predetermined space. The just-compressed liquid refrigerant is condensed within the proximate heat-exchanging component and then conveyed to the remote sink for the heat rejecting steps of the cycle.

SUMMARY

The following discloses a heatpump system which employs a natural refrigerant. A natural refrigerant is defined as a refrigerant which occurs naturally in significant quantity and which would not normally be present in the atmosphere in quantities which remain steady. In this manner, the remote heat-transferring sink can comprise an environmentally contaminable medium to which heat is rejected and/or from which heat is absorbed.
Using a naturally occurring refrigerant, such as carbon dioxide, allows the heatpump system to be environmentally friendly. Carbon dioxide contributes very little (if at all) to global warming, especially when compared to man-made refrigerants. And the risk of leakage does not equate to a fear of contamination with naturally occurring refrigerants as it may with man-made refrigerants. If carbon dioxide, for example, was to escape from the refrigerant-carrying circuit, and somehow seep into the sink medium, such a breach would not create any environmental concerns.
A naturally occurring refrigerant, such as carbon dioxide, can also have economic advantages. Man-made refrigerants can be very expensive, particularly in countries that highly regulate their manufacture and use. Carbon dioxide is cheap (a bit over $1/pound) and readily available. It is nonpoisonous (in any common concentration) and it is nonflammable, whereby no hidden costs are caused by safety or regulatory requirements during shipping or storing. Also, with a high-heat-transfer refrigerant such as carbon dioxide, money is indirectly saved by shorter loop lengths, less insulation, and decreased pipe diameters.
A naturally occurring refrigerant, such as carbon dioxide, also has some advantages related primarily to performance. Carbon dioxide provides some unique benefits because of its low critical temperature (i.e., the temperature above which it cannot be liquefied) and/or its inability to exist as a liquid in atmospheric pressure. In transcritical heating cycles, the large cooling temperature range of carbon dioxide (from about 80-90° C. to about 25-30° C.) makes for practical water heating steps. In subcritical cooling cycles, system efficiency can be enhanced, thanks to carbon dioxide's low compression ratio.
These and other features of the heatpump system are fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail certain illustrative embodiments, these embodiments being indicative of but a few of the various ways in which the principles may be employed.

DRAWINGS

FIGS. 1A and 1B are schematic diagrams of a heatpump system comprising a proximate heat-transfer component and a remote heat-transfer sink, the system being shown in a cooling mode in FIG. 1A and a heating mode in FIG. 1B.

FIGS. 2A and 2B show the heatpump system with an expander that decreases the pressure of the refrigerant after it has been condensed and/or cooled.

FIGS. 3A and 3B show the heatpump system with a heat exchanger that transfers heat from evaporated refrigerant to cooled refrigerant upstream.

FIGS. 4A and 4B show the heatpump system with a water heater.

FIGS. 5A and 5B show the heatpump system with an alternate heat-transfer-sink setup.

FIG. 6 schematically shows filtering components for the compressor.

DESCRIPTION

Referring now to the drawings, and initially to FIGS. 1A and 1B, a heatpump system 10 for controlling the temperature of a fluid within a predetermined space 12 is shown. For example, the system 10 could be used to control the temperature of air within a building or other structure. The heatpump system 10 is shown in a cooling mode in FIG. 1A and a heating mode in FIG. 1B.
The heatpump system 10 comprises a proximate heat-transferring component 14, a remote heat-transferring sink 16, a compressor 18, and a refrigerant-carrying circuit 20 that cycles a natural refrigerant (e.g., carbon dioxide) through these components. The heat-transferring component 14 is proximate (in or near) the predetermined space 12. The heat-transferring sink 16 is located remote (away from) the predetermined space 12.
The remote heat-transferring sink 16 comprises an environmentally contaminable medium to which heat is rejected and/or from which heat is absorbed. The refrigerant-carrying circuit 20 comprises conduit sections (e.g., generally-vertically-oriented loops) in heat-transfer relationship with this medium.
The environmentally contaminable medium can be soil and the relevant conduit sections can be buried therein.
The circuit 20 can comprise pipes, tubing, conduits, or any other fluid-conveying means. Copper piping (with or without thicker walls) can be used, thanks to the high operating temperature, the high heat transfer, and/or non-corrosive copper capability of carbon dioxide. With particular reference to ground loops associated with the remote sink, they can be relatively shorter than those used in analogous man-made-refrigerant systems.
As shown in FIGS. 2A and 2B, the heatpump system 10 can further comprise an expander 22 that decreases the pressure of the refrigerant after it has been cooled in the remote sink 16 (FIG. 2A) or the proximate component (FIG. 2B). In a subcritical cooling system, the expander 22 may allow the system 10 to reach coefficients of performance approximately equal to those of analogous man-made refrigerant systems. In a transcritical heating system, the expander's contribution will usually result in an improvement in performance.
As shown in FIGS. 3A and 3B, the heatpump system 10 can comprise a heat exchanger 24 that transfers heat from evaporated refrigerant to cooled refrigerant.
As shown in FIGS. 4A and 4B, the heatpump system can comprise a receptacle 26 into which water is heated by a section of the refrigerant-carrying circuit passing therethrough. Such a water-heating function would not be feasible with most man-made refrigerants, due to their low operating temperatures.
In the 1^st-4^thdrawing sets, the heat-sink medium was soil and generally vertically oriented loops were buried therein. As shown in FIGS. 5A and 5B, the environmentally contaminable medium can be water and the relevant refrigerant-carrying circuit sections can be immersed therein. Horizontally (rather than vertically) oriented loops may be more convenient when a stream, pond, or other body of water serves as the sink's medium.
As was mentioned above, the heatpump system 10 comprises a compressor 18 that compresses the refrigerant at the appropriate point in the cycle. To enhance the environmental-friendliness features of the heatpump system 10, filters 30 can be provided to prevent oil from being transferred into the refrigerant-carrying circuit 20 and becoming a contamination threat when traveling through the sink loops. Monitors 32 can be used to actively monitor the performance or state of the filters 30.
When the heatpump system 10 is used to cool the fluid within the predetermined space 12, heat is absorbed from this fluid by evaporating the refrigerant as it passes through the proximate heat-transfer component 14. The heat is then rejected to the medium by cooling the refrigerant as it passes through the remote heat-transfer sink 16. The heat-rejecting step can be performed below the refrigerant's critical point and its temperature can stay constant during the heat-rejecting step. In such a subcritical cycle, the refrigerant can be condensed to a liquid during the heat-rejecting step.
When the heatpump system 10 is used to heat the fluid within the predetermined space 12, heat is rejected to this fluid by cooling the refrigerant as it passes through the proximate heat-transfer component. The refrigerant then absorbs heat from the heat sink medium when it is evaporated when passing therethrough. The heat-rejecting step can be performed above the critical point of the refrigerant and its temperature can decrease during the heat-rejecting step. In such a transcritical cycle, the refrigerant is cooled, but not condensed, during said heat-rejecting step.
Although the heatpump system 10 has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In regard to the various functions performed by the above described elements (e.g., components, assemblies, systems, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.

Claims

1. A heatpump system for controlling the temperature of a fluid within a predetermined space, said system comprising:

a naturally occurring refrigerant;

a proximate heat-transferring component located proximate to predetermined space;

a remote heat-transferring sink located remote from the predetermined space and comprising an environmentally contaminable medium to which heat is rejected and/or from which heat is absorbed; and

a refrigerant-carrying circuit for cycling the refrigerant through the heat-transferring component and the remote heat-transferring sink.

2. A heatpump system as set forth in claim 1, wherein the refrigerant is carbon dioxide.

3. A heatpump system as set forth in claim 2, wherein the environmentally contaminable medium is not a gas.

4. A heatpump system as set forth in claim 3, wherein the refrigerant-carrying circuit comprises conduit sections in heat-transfer relationship with the medium.

5. A heatpump system as set forth in claim 4, wherein the conduit sections are positioned in a generally vertical orientation.

6. A heatpump system as set forth in claim 4, wherein the conduit sections are positioned in a generally horizontal orientation.

7. A heatpump system as set forth in claim 4, wherein the environmentally contaminable medium is soil and wherein the conduit sections are buried in the soil.

8. A heatpump system as set forth in claim 4, wherein the environmentally contaminable medium is water and wherein the conduit sections are immersed in the water.

9. A heatpump system as set forth in claim 4, further comprising a compressor which compresses the refrigerant after it has been evaporated in either the proximate heat-transfer component or the remote heat-transfer sink.

10. A heatpump system as set forth in claim 9, further comprising filters to prevent oil from being transferred into the conduit sections in heat-transferring relationship with the environmentally contaminable medium of the remote sink.

11. A heatpump system as set forth in claim 10, further comprising monitors for actively monitoring the performance or status of the filters.

12. A heatpump system as set forth in claim 9, further comprising an expander that decreases the pressure of the refrigerant after it has been cooled in either the proximate heat-transferring component or the remote heat-transferring sink.

13. A heatpump system as set forth in claim 12, further comprising a heat exchanger that transfers heat from evaporated refrigerant to cooled refrigerant.

14. A heatpump system as set forth in claim 12, further comprising a receptacle into which water is heated by a section of the refrigerant-carrying circuit passing therethrough.

15. A method of cooling a fluid within a predetermined space with the heatpump system set forth in claim 1, said method comprising the steps of:

absorbing heat from the to-be-cooled fluid by evaporating the refrigerant as it passes through the proximate heat-transfer component; and

rejecting heat to the environmentally contaminable medium by cooling the refrigerant as it passes through the remote heat-transfer sink.

16. A method as set forth in claim 15, wherein said heat-rejecting step is performed below the critical point of the refrigerant and wherein the temperature of the refrigerant stays constant during the heat-rejecting step.

17. A method as set forth in claim 16, wherein the refrigerant is condensed to a liquid during the heat-rejecting step.

18. A method of heating a fluid within a predetermined space with the heatpump system set forth in claim 1, said method comprising the steps of:

rejecting heat to the to-be-heated fluid by cooling the refrigerant as it passes through the proximate heat-transfer component; and

absorbing heat from the environmentally contaminable medium by evaporating the refrigerant as it passes through the remote heat-transfer sink.

19. A method as set forth in claim 18, wherein said heat-rejecting step is performed above the critical point of the refrigerant and wherein the temperature of the refrigerant decreases during the heat-rejecting step.

20. A method as set forth in claim 19, wherein the refrigerant is cooled, but not condensed, during said heat-rejecting step.