US20190017733A1

US20190017733A1 - Heat exchanger for use with earth-coupled air conditioning systems

Info

Publication number: US20190017733A1
Application number: US16/136,658
Authority: US
Inventors: Roger G. EDWARDS
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-06-03
Filing date: 2018-09-20
Publication date: 2019-01-17
Also published as: US20170350629A1

Abstract

An air handling system that includes at least one earth-coupled heat exchanger assembly that further includes a first pipe section having an inner diameter and an outer diameter; a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section includes an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, and wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein; and a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section includes an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween.

Description

This patent application is a continuation of U.S. patent application Ser. No. 15/173,077 filed on Jun. 3, 2016 and entitled “Heat Exchanger for Use with Earth-Coupled Air Conditioning Systems”, the disclosure of which is hereby incorporated by reference herein in its entirety and made part of the present U.S. utility patent application for all purposes.

BACKGROUND OF THE INVENTION

The described invention relates in general to air handling and air conditioning systems, devices, and methods, and more specifically to an air handling system that includes a plurality of earth-coupled heat exchangers that increase system efficiency.
Earth-coupled or ground-coupled heating and cooling systems are widely utilized for efficiently providing environmental heating and cooling or process heating and cooling. A primary advantage of earth-coupled systems is the relatively constant temperature of subsurface soil, which provides a readily accessible source/sink for heating and cooling equipment. There are two basic types of earth-coupled systems. A first general type of system utilizes water source heat pump units that are connected to either ground water or other bodies of water that are pumped through the units to provide the source/sink for the units. Another variation of this earth-coupled system is a closed loop with piping extending down into wells bored into the earth or laid in shallow ditches and covered with earth. These systems can utilize either water or antifreeze as a transfer medium. The second general type of system is referred to as direct-coupled. A direct-coupled system utilizes refrigerant piping directly inserted into wells similar to the closed loop water system previously described.
A significant disadvantage of well systems such as those described above is that these systems require piping to be installed with down pipes and risers together in a common well. When installed in this manner, the pipes transfer heat to each other along with the surrounding earth. Heat transfer between the pipes reduces total heat transfer to the earth and, therefore, requires more wells or deeper wells to achieve the desired heat transfer to the soil. Therefore, the net effect caused by two pipes transferring heat to each other is a reduction in the efficiency of the system, thus requiring a larger and more expensive heat exchanger to be installed. Accordingly, there is an ongoing need for a highly efficient, cost-effective heat exchanger for use with earth-coupled heating and cooling systems.

SUMMARY OF THE INVENTION

The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope.
In accordance with one aspect of the present invention, a first air-handling system is provided. This air handling system includes at least one earth-coupled heat exchanger assembly, wherein the at least one earth-coupled heat exchanger assembly includes a first pipe section having an inner diameter and an outer diameter; a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section has an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, and wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein; and a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section has an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween.
In accordance with another aspect of the present invention, a second air-handling system is provided. This air handling system includes a plurality of earth-coupled heat exchanger assemblies each of which includes a first pipe section having an inner diameter and an outer diameter; a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section has an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, and wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein; and a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section has an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween; a plurality of individual liquid lines, wherein each line is connected to the first pipe section of an earth-coupled heat exchanger assembly; and a plurality of hot gas suction lines, wherein each line is connected to the third pipe section of an earth-coupled heat exchanger assembly and is communication with the passageway formed between the outer diameter of the second pipe and the inner diameter of the third pipe section
In yet another aspect of this invention, a third air handling system is provided. This air handling system includes a plurality of earth-coupled heat exchanger assemblies, each of which includes a first pipe section having an inner diameter and an outer diameter, wherein the first pipe section further includes a gas expansion device attached to the bottom portion thereof; a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section has an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, and wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein; and a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section has an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween; a plurality of individual liquid lines, wherein each line in the plurality of individual liquid lines is connected to the first pipe section of an earth-coupled heat exchanger assembly at one end thereof and to a solenoid valve at the other end thereof, wherein each solenoid valve is connected to a manifold, wherein the manifold is connected to a main liquid line, and wherein the main liquid line is connected to the coil of an indoor air conditioning unit; and a plurality of hot gas suction lines, wherein each line in the plurality of hot gas suction lines is connected to the third pipe section of an earth-coupled heat exchanger assembly and is communication with the passageway formed between the outer diameter of the second pipe and the inner diameter of the third pipe section, wherein each hot gas suction line is connected to a main hot gas suction line, and wherein the main hot gas suction line is connected to a compressor.
Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein:

FIG. 1 is a schematic of an air handling system in accordance with an exemplary embodiment of the present invention, wherein the system is operating in cooling mode;

FIG. 2 is a schematic of an air handling system in accordance with an exemplary embodiment of the present invention, wherein the system is operating in heating mode;

FIG. 3 is a cross-sectional side view of a heat exchanger assembly in accordance with an exemplary embodiment of the present invention; and

FIG. 4 is a cross-sectional top view of the heat exchanger of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention are now described with reference to the Figures. Reference numerals are used throughout the detailed description to refer to the various elements and structures. Although the following detailed description contains many specifics for the purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.
The present invention provides systems and devices for improving heat transfer in earth-coupled exchange systems commonly referred to as geothermal heating systems. Such systems are actually geo-exchange systems that utilize the relatively constant temperatures found in the soil below the surface of the earth. This invention permits a greatly reduced heat transfer to occur between the two pipes by disposing one pipe within the other pipe with the region between the two pipes evacuated to a vacuum. By way of comparison, the vacuum condition that exists between the two pipes reduces conductive heat transfer in the same manner that a thermos bottle reduces heat transfer. The ability to maintain a near perfect vacuum in the region between the two pipes improves the efficiency of the heat exchange to the earth. The highly efficient design of this invention also allows the system to operate with much greater temperature differentials than are normally associated with geo-exchange systems, thereby permitting a much smaller, less expensive system to provide capacity equivalent to larger, more expensive systems.
With reference to the Figures, FIG. 1 depicts an exemplary embodiment of the heating system of the present invention in its cooling mode and FIG. 2 depicts the same system in its heating mode. In both FIG. 1 and FIG. 2, air handling system 100 includes air conditioning unit 200, which further includes indoor unit 202 that houses coil 204 and expansion device or valve 206, to which main liquid line 300 is connected. Manifold 302 is connected to main liquid line 300 and further includes a plurality of in-line solenoid valves 304 to which individual liquid lines 306 are connected. Suction flow line 400 is connected to refrigerant reversing valve 402, accumulator 404, and compressor 406. Compressor 406 is also connected to hot gas flow line 408, which is connected to a plurality of individual hot gas/suction lines 410. Each individual liquid line 306 and individual hot gas/suction line 410 is connected to an individual heat exchanger assembly 500. As described in greater detail below, in FIGS. 1-2, the direction of refrigerant and/or hot gas flow is indicated by arrows A and B (FIG. 1) and C and D (FIG.2).
Each individual heat exchanger assembly 500 includes multiple pipe sections, which are concentrically arranged with regard to one another. With reference to FIGS. 3 and 4, the innermost pipe section in each heat exchanger assembly 500 is first pipe section 510, which is connected to an individual liquid line 306 at its upper end and an expansion device/piston assembly 512 at its lower end. First pipe section 510 is disposed within second pipe section 520, which surrounds a portion of first pipe section 510 and which is connected thereto at its lower end by connector 522. Because the outer diameter of first pipe section 510 is smaller than the inner diameter of second pipe section 520, a cylindrical space or region 524 is formed between these two pipe sections. Air in region 524 is evacuated to create an insulating vacuum between first pipe section 510 and second pipe section 520. A portion of second pipe section 520 is disposed within third pipe section 530. Connector 532 seals the upper portion of third pipe section 530 and cap 534 seals the lower portion of third pipe section 530. Connector 532 also attaches to an individual hot gas/suction line 410. Because the outer diameter of second pipe section 520 is smaller than the inner diameter of third pipe section 530, a cylindrical space or region 536 is formed between these two pipe sections. This space or region provides passage 536 for a refrigerant (as a hot gas) to flow within heat exchanger assembly 500. Each heat exchanger assembly 500 includes at least one spacer 540 for maintain the proper distance between the three pipe sections and adding structural stability to the heat exchanger assembly.
Each heat exchanger assembly 500 utilizes refrigerant to transfer heat directly to or from the earth and the concentric design of each heat exchanger assembly 500 allows third pipe section 530, which is the outermost pipe section, to directly contact the earth when properly installed. In an exemplary embodiment, each pipe section is constructed from ACR (air conditioning and refrigeration field services) copper pipe and fittings. For example, in an exemplary embodiment, first pipe section 510 is constructed from ⅜ inch ACR copper pipe; second pipe section 520 is constructed from ⅞ inch ACR copper pipe; and third pipe section 530 is constructed from 1 and ⅛ inch ACR copper pipe. In some embodiments, hot gas/suction passage 536 is enhanced through the placement of a spiral structure or device 537 therein, which causes the refrigerant to move through passage 536 in a swirling motion. This swirling motion or swirling action causes a turbulent gas flow to occur and increases the heat transfer path length as the refrigerant flows through heat exchanger assembly 500. The spiral structure may be formed around the inner diameter of third pipe section 530 from the material of the pipe, or the spiral structure may be a separate component that is inserted into the interstitial space between second pipe section 520 and third pipe section 530. Refrigerant passing through outer or third pipe section 530 enters heat exchanger assembly 500 at the top portion thereof as high temperature, high pressure gas, or enters at the bottom through expansion device/piston assembly 512 as low temperature, low pressure gas. First pipe section 510, which is the smallest and innermost pipe section conveys liquid refrigerant through heat exchanger assembly 500, with the direction of the flow being determined by the mode of operation of the system (i.e., either heating or cooling), as described in greater detail below.
With reference to FIG. 1, when air handling system 100 is operating in cooling mode as a cooling unit, high-pressure liquid refrigerant travels upward through first pipe section 510 to expansion valve 206 (located at coil 204 of indoor unit 202), where it becomes a low-pressure, low-temperature gas. After passing through expansion valve 206, this low-pressure, low-temperature gas absorbs heat from the air to be cooled or process to be cooled, thereby providing the desired cooling effect. The low-pressure gas then enters compressor 406, where it is compressed to high-temperature, high-pressure gas. This high-pressure, high-temperature gas then travels through hot gas flow line 408 and individual hot gas/suction lines 410 to heat exchanger assemblies 500. The high-pressure, high-temperature gas then travels downward through hot gas/suction passage 536 and transfers heat to the soil surrounding the exterior of third pipe section 530. Vacuum space 524 reduces heat transfer between hot gas/suction passage 536 and first pipe section 510, which is the passageway for the liquid refrigerant. When the high-pressure, high-temperature gas reaches the bottom area of heat exchanger assembly 500, the gas has condensed into high-pressure, low-temperature liquid refrigerant. The liquid refrigerant then bypasses expansion device/piston assembly 512 and enters first pipe section 510. The entire process then repeats.
With reference to FIG. 2, when air handling system 100 is operating in heating mode as a heating unit, high-pressure liquid refrigerant travels from coils 204 of indoor unit 202 through main liquid line 300, manifold 302, solenoid valves 304, and individual liquid lines 306 to plurality of heat exchanger assemblies 500. The high-pressure liquid refrigerant travels then travels downward through first pipe section 510 to the bottom portion of each heat exchanger assembly 500 where it then passes through expansion device/piston assembly 512. After passing through expansion device/piston assembly 512, the refrigerant enters hot gas/suction passage 536 as low-pressure, low-temperature gas. This low-pressure, low-temperature gas then travels up through hot gas/suction passage 536 and absorbs heat from the surrounding earth. Vacuum space 524 reduces heat transfer between hot gas/suction passage 536 and first pipe section 510. Warmed low-pressure gas then travels to the suction inlet of compressor 406 where it is compressed into high-temperature, high-pressure gas. This hot gas then travels to coils 204 of indoor unit 202 where it transfers heat to the air or a process being heated and effectively heats the space or process conditioned by indoor unit 202 while condensing into high-pressure liquid. The cycle is then complete and the entire process repeats.
The two modes of operation discussed above, i.e., heating and cooling, are commonly associated with heat pumps, which are utilized for heating and cooling of interior spaces. The advantage of earth-coupled systems is the increased efficiency that results from utilizing the stable temperatures of the earth at depths deeper than about four feet below normal grade. Air handling or air conditioning systems that utilize wells or horizontal water-based apparatuses require considerable physical space and more material is necessary for achieving the system capacity required for most residences or other structures. Increased space requirements and greater required depths for wells results in increased costs and extends the period of time required to recover installation and materials costs based on added or increased system efficiency. Accordingly, such additional expenses often prevent an air handing installation from being cost-effective at all unless energy cost are truly excessive. Improving the efficiency of an earth-coupled heat exchanger permits a reduction in overall size of the system when installed and reduces the cost of the required installation.
With regard to the present invention, and as shown in FIGS. 1-2, an exemplary system installation includes a common hot gas/suction line 408, which serves a plurality of earth coupled heat exchanger assemblies 500, as well as individual liquid lines 306 connected to each heat exchanger assembly 500. This configuration permits heat exchanger assemblies 500 to be activated individually. Individual liquid lines 306 are connected to manifold 302, which includes electrically operated solenoid valves 304 that are used to select which heat exchanger assemblies 500 are active at any given time. The ability to select the number of heat exchanger assemblies 500 that are active can be used for load matching and performance optimization. If a compressor unit is used that includes part load capacity control such as a variable speed control or other method for part load operation, the number of active heat exchanger assemblies 500 can be selected to match the actual system load. Assuring that there are more heat exchanger assemblies 500 installed than are actually required for the maximum anticipated load, provides at least one inactive heat exchanger assembly 500 at all times. This arrangement permits system 100 to use a rotating sequence for optimizing system performance based on temperatures measured from each heat exchanger assembly 500.
Temperature sensors are typically installed on individual liquid lines 306 for monitoring the performance of each heat exchanger assembly 500. System 100, which includes a controller (not shown in the Figures), determines the least effective heat exchanger assembly 500 using a time-based algorithm and when that particular heat exchanger assembly passes a pre-determined threshold, system 100 takes that unit offline and a unit that was previously taken offline is then reactivated. This sequence optimizes the performance of system 100 by providing the earth surrounding each heat exchanger assembly 500 with a rest period to recover during peak periods of operation.
While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, there is no intention to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.

Claims

1. An air handling system, comprising:

(a) at least one earth-coupled heat exchanger assembly, wherein the at least one earth-coupled heat exchanger assembly is adapted to be buried in the earth and includes:

(i) a first pipe section, wherein the first pipe section includes an inner diameter and an outer diameter;

(ii) a heat-transfer reducing insulator that includes a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section includes an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein, and

(iii) a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section includes an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween,

(iv) wherein the heat-transfer reducing insulator is operative to reduce heat transfer between the first pipe section and the third pipe section and improve efficiency of heat transfer between the third pipe section and the earth.

2. The system of claim 1, further comprising a gas expansion device connected to the first pipe section at the bottom portion thereof.

3. The system of claim 1, further comprising a turbulence-inducing spiral structure disposed within the third pipe section.

4. The system of claim 1, further comprising a stabilizing spacer disposed within the third pipe section.

5. The system of claim 1, further comprising a plurality of individual liquid lines, wherein each line in the plurality of individual liquid lines is connected to the first pipe section of an earth-coupled heat exchanger assembly.

6. The system of claim 5, further comprising a solenoid valve connected to each individual liquid line upstream from each earth-coupled heat exchanger assembly.

7. The system of claim 6, wherein each solenoid valve is connected to a manifold, wherein the manifold is connected to a single liquid line, and wherein the single liquid line is connected to the coil of an indoor air conditioning unit.

8. The system of claim 1, further comprising a plurality of hot gas suction lines, wherein each line in the plurality of hot gas suction lines is connected to the third pipe section of an earth-coupled heat exchanger assembly and is communication with the passageway formed between the outer diameter of the second pipe and the inner diameter of the third pipe section.

9. The system of claim 8, wherein each hot gas suction line is connected to a main hot gas suction line, and wherein the main hot gas suction line is connected to a compressor.

10. An air handling system, comprising:

(a) a plurality of earth-coupled heat exchanger assemblies, wherein each earth-coupled heat exchanger assembly in the plurality of earth-coupled heat exchanger assemblies is adapted to be buried in the earth and includes:

(ii) a heat-transfer reducing insulator that includes a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section includes an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, and wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein; and

(iii) a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section includes an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween, wherein the heat-transfer reducing insulator is operative to reduce heat transfer between the first pipe section and the third pipe section and improve efficiency of heat transfer between the third pipe section and the earth;

(b) a plurality of individual liquid lines, wherein each line in the plurality of individual liquid lines is connected to the first pipe section of an earth-coupled heat exchanger assembly; and

(c) a plurality of hot gas suction lines, wherein each line in the plurality of hot gas suction lines is connected to the third pipe section of an earth-coupled heat exchanger assembly and is communication with the passageway formed between the outer diameter of the second pipe and the inner diameter of the third pipe section.

11. The system of claim 10, further comprising a gas expansion device connected to the first pipe section at the bottom portion thereof.

12. The system of claim 10, further comprising a turbulence-inducing spiral structure disposed within the third pipe section.

13. The system of claim 10, further comprising a stabilizing spacer disposed within the third pipe section.

14. The system of claim 10, further comprising a solenoid valve connected to each individual liquid line upstream from each earth-coupled heat exchanger assembly.

15. The system of claim 14, wherein each solenoid valve is connected to a manifold, wherein the manifold is connected to a single liquid line, and wherein the single liquid line is connected to the coil of an indoor air conditioning unit.

16. The system of claim 10, wherein each hot gas suction line is connected to a main hot gas suction line, and wherein the main hot gas suction line is connected to a compressor.

17. An air handling system, comprising:

(i) a first pipe section, wherein the first pipe section includes an inner diameter and an outer diameter, and wherein the first pipe section further includes a gas expansion device attached to the bottom portion thereof;

(b) a plurality of individual liquid lines, wherein each line in the plurality of individual liquid lines is connected to the first pipe section of an earth-coupled heat exchanger assembly at one end thereof and to a solenoid valve at the other end thereof, wherein each solenoid valve is connected to a manifold, wherein the manifold is connected to a main liquid line, and wherein the main liquid line is connected to the coil of an indoor air conditioning unit; and

(c) a plurality of hot gas suction lines, wherein each line in the plurality of hot gas suction lines is connected to the third pipe section of an earth-coupled heat exchanger assembly and is communication with the passageway formed between the outer diameter of the second pipe and the inner diameter of the third pipe section, wherein each hot gas suction line is connected to a main hot gas suction line, and wherein the main hot gas suction line is connected to a compressor.

18. The system of claim 17, further comprising a turbulence-inducing spiral-shaped structure disposed within the third pipe section.

19. The system of claim 17, further comprising a stabilizing spacer disposed within the third pipe section.

20. The system of claim 17, wherein each earth-coupled heat exchanger assembly is adapted to be operated separately from the other earth-coupled heat exchanger assemblies.