Portable subcooler for refrigerant recovery and method

Abstract

A portable supercooling device includes a housing having enclosed therein a compressor for pressurizing a cooling refrigerant, and a condenser in fluid communication with the compressor for removing heat from the cooling refrigerant, and a heat exchange evaporator coil for absorbing heat from a recovery refrigerant, the evaporator coil including first, second and third heat absorbing coils and first and second heat transfer coils, wherein the third heat absorbing coil is concentrically nested within the first heat transfer coil, the first heat transfer coil is concentrically nested within the second heat absorbing coil, the second heat absorbing coil is concentrically nested within the second heat transfer coil, and the second heat transfer coil is concentrically nested within the first heat absorbing coil.

Description

background Technical Field

[0001] This disclosure relates generally to refrigeration, and more specifically to refrigerant recovery, and even more specifically to subcooled refrigerants for recovery. Background Technology

[0002] Recovering refrigerant from refrigeration or heating, ventilation, and air conditioning (“HVAC”) systems is a crucial part of maintaining or decommissioning these systems to prevent environmental hazards and ensure compliance. Federal regulations in many countries, including the United States, require the recycling or reuse of refrigerants wherever possible to minimize environmental impact. The U.S. Environmental Protection Agency (EPA) has regulations governing the handling, recycling, and disposal of refrigerants used in stationary refrigeration and air conditioning systems, enacted under Section 608 of the Clean Air Act. These regulations require refrigerants to be recovered and recycled to meet industry standards before being reused in the same equipment or other systems. This helps reduce emissions of ozone-depleting substances and greenhouse gases, which can contribute to climate change and harm the environment. Refrigerant recovery and recycling equipment must be EPA certified to ensure it meets specific standards for the safe and efficient handling of refrigerants. Furthermore, technicians working with refrigerants must be EPA certified to legally handle and use these substances. By recycling or regenerating refrigerants, HVAC professionals can help protect the environment and comply with federal regulations designed to mitigate the atmospheric impact of refrigerants.

[0003] Section 608 of the Clean Air Act also prohibits the intentional release of refrigerant during the maintenance, service, repair, or disposal of air conditioning (AC) and refrigeration equipment. Furthermore, according to Section 608, refrigerant must be recovered in its pure form, must not be mixed with other substances, and must not be released into the atmosphere. In practice, it is generally preferred to recover refrigerant in its liquid form because it is easier to handle and store. Moreover, recovering refrigerant in liquid form helps prevent the release of refrigerant vapors into the atmosphere, which is important for both environmental and safety reasons. Although Section 608 does not explicitly require the recovery of refrigerant in its liquid state, it is generally considered best practice in the HVAC industry to recover refrigerant in its pure form and minimize refrigerant release into the atmosphere.

[0004] When refrigerant is drawn from a refrigeration system for recovery, the substance is typically at its saturation temperature, meaning it is in equilibrium between its liquid and gas phases. Therefore, to minimize the risk of releasing refrigerant vapor into the atmosphere, the refrigerant is subcooled during the drawing process. Subcooling is the process in a refrigeration cycle used to lower the temperature of the refrigerant below its saturation temperature. This subcooling process helps ensure that the refrigerant remains liquid and free of vapor when it is stored for reuse or disposal.

[0005] Some refrigerant recovery machines (typically including a compressor or pump) may have a built-in subcooler or other cooling mechanism to help lower the temperature of the recovered refrigerant. However, not all recovery machines include this feature, as it depends on the machine's specific design and intended use. An example of a refrigerant recovery machine that includes a subcooler is the Appion® G5Twin dual-cylinder recovery unit. This unit features a built-in subcooler, which aims to ensure that the recovered refrigerant is liquid and free of any vapors before being transferred to the storage tank. Another example is the Robinair® RG6 portable refrigerant recovery machine, which also includes a subcooler to help improve the efficiency of the recovery process and ensure that the recovered refrigerant is in a suitable condition for reuse or recycling.

[0006] However, these systems may still require additional subcooling of the discharged refrigerant. The refrigerant discharged from the system under maintenance is at high temperature and pressure. High ambient temperatures reduce the efficiency of the refrigerant recovery unit because the pump needs to work harder to achieve the same level of refrigerant recovery. Besides increasing the maintenance costs of the recovery unit, this can also lead to longer recovery times and increased energy consumption. Furthermore, when the recovery unit operates in high-temperature environments, the storage tank pressure may rise. Without subcooling, the discharge pressure of the recovery unit during refrigerant recovery varies between 200-375 psi as the tank is being filled to its nominal capacity. Operating at high ambient temperatures can increase the pressure of the refrigerant being recovered in the storage tank, potentially exceeding the tank's rated pressure capacity. This can pose a safety hazard and may require additional precautions to prevent overpressure. Increased tank pressure also reduces the rate of refrigerant recovery because the higher pressure in the tank hinders the flow of refrigerant from the system under maintenance to the recovery unit. This can lead to longer recovery times and increased energy consumption.

[0007] Newer synthetic refrigerants (R410a) containing chlorine atoms tend to expand at higher pressure rates than their original organic counterparts. R410A and 134A will begin to be phased out by 2025. New replacement refrigerants will be classified as A2L, meaning they will have an A2L flammability rating and a lower critical pressure point. The new refrigerant R1234YF has a lower critical pressure rating (490 psi) than the current R410A (709 psi), leading to a greater need for systems that provide continuous refrigerant recovery through mechanical subcooling.

[0008] To address this deficiency, a "molecular converter" is typically used to further cool the refrigerant before it is introduced into the storage tank. The molecular converter, available as the Pro-Set® MT69 from CPS Products, Inc., is essentially an auxiliary subcooler that alters the molecular structure of the discharged refrigerant to promote its condensation into a liquid form. It is inserted into the recovery process between the recovery unit and the storage tank. The device is immersed in an ice bath as the cooling medium. This is designed to help accelerate recovery time by keeping the refrigerant at a low temperature / low pressure upon entering the tank. Discharge pressure can be reduced by 40% by using the subcooling device.

[0009] However, the temperature of the ice bath is not constant, especially during periods of high ambient temperature. The refrigerant flowing through the unit may still be at high temperature / pressure because it was not properly subcooled in the recovery unit. This causes the ice to melt rapidly, requiring constant replenishment of the ice bath, which translates to higher costs in terms of both money (for ice) and labor time. Therefore, the temperature of the ice bath can vary from 36°F to 56°F, which in turn leads to variations in the temperature and pressure of the recovered refrigerant.

[0010] An apparatus and method are needed to address these shortcomings and provide consistent subcooling for discharged refrigerant to improve process efficiency and safety while minimizing or eliminating the risk of greenhouse gas emissions. Summary of the Invention

[0011] For the purposes of overview, certain aspects, advantages, and novel features are described herein. It should be understood that not all of these advantages can necessarily be achieved according to any particular embodiment. Therefore, the claimed apparatus or method may be implemented or performed in a manner that achieves or optimizes one or more advantages taught herein, without necessarily achieving other advantages that may be taught or suggested herein.

[0012] A portable subcooling device includes a housing enclosed within which is a compressor for pressurizing a cooling refrigerant and a condenser in fluid communication with the compressor for removing heat from the cooling refrigerant, and a heat exchange evaporator coil for absorbing heat from the recovered refrigerant. The evaporator coil includes a plurality of heat-absorbing coils in fluid communication with the condenser and the compressor, and a plurality of heat-transfer coils for conveying the recovered refrigerant, the plurality of heat-transfer coils being thermally connected to the plurality of heat-absorbing coils.

[0013] On one hand, the heat exchange evaporator coil includes a first heat-absorbing coil, a second heat-absorbing coil, and a third heat-absorbing coil, as well as a first heat-transfer coil and a second heat-transfer coil, wherein the third heat-absorbing coil is concentrically nested within the first heat-transfer coil, the first heat-transfer coil is concentrically nested within the second heat-absorbing coil, the second heat-absorbing coil is concentrically nested within the second heat-transfer coil, and the second heat-transfer coil is concentrically nested within the first heat-absorbing coil.

[0014] A method for refrigerant recovery using the disclosed apparatus includes the following steps: providing high-temperature, high-pressure refrigerant to a first heat transfer coil and a second heat transfer coil, the first and second heat transfer coils being thermally connected to a first heat absorption coil, a second heat absorption coil, and a third heat absorption coil, the first, second, and third heat absorption coils being components of a closed-loop refrigeration circuit enclosed within a housing; then providing cooling refrigerant to the first, second, and third heat absorption coils through the refrigeration circuit; and finally, discharging cooled and depressurized refrigerant from the second heat transfer coil. Attached Figure Description

[0015] The device is described with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar functional elements. Furthermore, the leftmost numeral of the reference numerals indicates the drawing in which that reference numeral first appears.

[0016] Figure 1 This is a functional schematic diagram of an exemplary refrigerant cooling device according to an embodiment; and Figure 2 yes Figure 1 The diagram of the device shows the evaporator coil in more detail. Detailed Implementation

[0017] By reference Figure 1 and Figure 2 This allows for a better understanding of the various embodiments of the sleep surface and their advantages. The elements in the accompanying drawings are not necessarily drawn to scale; rather, the focus is on clearly illustrating novel features and operating principles. In all the drawings, the same numerals are used to denote identical and corresponding parts in each drawing.

[0018] Furthermore, references to "embodiment," "one embodiment," "various embodiments," or any variations thereof in the specification mean that a particular feature or aspect described in connection with that particular embodiment is included in at least one embodiment. Therefore, the phrases "in one embodiment," "in another embodiment," or variations thereof appearing throughout the specification do not necessarily refer to their respective embodiments.

[0019] Figure 1 This is a functional schematic diagram of a refrigerant subcooling device 100, which includes a power supply 109 that operates to provide suitable power 102 to the compressor 103 and the fan motor 107 driving the fan 113. The power to the compressor 103 and the fan motor 107 can be 120V from an external source. The compressor 103 moves the subcooled refrigerant through the refrigeration circuit described below. The compressor 103 is any compression device suitable for a 4000 BTU circuit. Preferably, the compressor 103 is a spark-free rotary compressor.

[0020] The subcooling unit 100 also includes a condenser 105 in fluid communication with the compressor 103. A heat exchange evaporator coil (HEEC) 101 is in fluid communication with the condenser 105, with a filter dryer 111 inserted between them. The unit 100 includes a housing 115 that encloses the aforementioned components. The housing 115 is configured with a heat exhaust outlet 117 and a return air inlet 119. The condenser 105 may, for example, include one or more coiled tubes for conveying refrigerant, or one or more tube bundles formed by multiple tubes for conveying refrigerant, which cross a flow path leading to the heat exhaust outlet 117. The condenser 105 may be a three-coil condenser rated for a 4000 BTU refrigeration circuit. The fan motor 107 is also preferably non-sparking. The fan 113 operates to pass air (typically ambient air) through the tubes of the condenser 105 to cool the refrigerant vapor flowing through the tubes.

[0021] In operation, subcooled refrigerant is drawn in by compressor 103 through suction line 110 and discharged to condenser 105 through compressor discharge line 104. Simultaneously, fan 113, driven by motor 107, blows cooling air across condenser 105, thereby removing heat from the subcooled refrigerant flowing through condenser 105. The rejected heat 118 is discharged through hot outlet 117. The subcooled refrigerant becomes liquid in condenser 105 and is drawn out of condenser 105 through condenser discharge line 106, flowing through filter dryer 111, which removes excess moisture, contaminants, and acids from the subcooled refrigerant. Dryer 111 can be a liquid-filled dryer, also known as a liquid-line filter dryer.

[0022] Subcooled refrigerant is then supplied to HEEC 101 via evaporator supply line 112 for heat absorption. Simultaneously, recovered refrigerant, i.e., refrigerant to be recovered from the refrigeration system under maintenance, is supplied to HEEC 101 through recovered refrigerant inlet 114. The recovered refrigerant is cooled and discharged through subcooled refrigerant outlet 116. Meanwhile, return air 120 is drawn in through return air inlet 119. The high-side pressure range can be from approximately 285 to approximately 305 psi, and the low-side pressure from approximately 100 to approximately 120 psi, depending on the ambient load.

[0023] Figure 2 The HEEC 101 within the device 100 is shown in more detail. For clarity, the housing 115 and fan 113 are not shown. The HEEC 101 includes a distributor 211 in an inlet supply line 112 extending from the dryer 111. A first capillary 202, a second capillary 204, and a third capillary 206 branch off from the distributor 211. It should be understood that the distributor 211, as well as the dryer 111, includes a metering device 213.

[0024] A first capillary tube 202 extends from distributor 211 to a first absorber coil 201, which includes a first absorber coil discharge line 208. A second capillary tube 204 extends from distributor 211 to a second absorber coil 203, which includes a second absorber coil discharge line 210. Finally, a third capillary tube 206 extends from distributor 211 to a third absorber coil 205, which includes a third absorber coil discharge line 212. The coil discharge lines 208, 210, and 212 are in fluid communication with the HEEC return line 214, which serves as the compressor suction line 110 exiting the HEEC 101. It should be noted that the condenser discharge line 106 and the suction line 110 are preferably provided with service ports 108a and 108b. Therefore, the heat absorption coils 201, 203, and 205, together with the compressor 103, the condenser 105, and the metering device 213, constitute an internal closed-loop refrigeration circuit.

[0025] HEEC 101 also includes a first heat transfer coil 207 that receives recovered refrigerant from an external source through inlet 114 and has a first transfer coil outlet 216. The coil outlet 216 is in fluid communication with the suction line 218 of a second heat transfer coil 209, which has a second transfer coil outlet 220 in fluid communication with a subcooled refrigerant outlet 116. Inlet 114 and outlet 116 may be ¼-inch fittings of HVAC standard.

[0026] The third heat-absorbing coil 205 has an outer diameter smaller than the inner diameter of the first heat-transfer coil 207, whose outer diameter is smaller than the inner diameter of the second heat-absorbing coil 203. The outer diameter of the second heat-absorbing coil 203 is smaller than the inner diameter of the second heat-transfer coil 209. Finally, the second heat-transfer coil 209 has an outer diameter smaller than the inner diameter of the first heat-absorbing coil 201. Therefore, the third heat-absorbing coil 205 is concentrically nested within the first heat-transfer coil 207, which is nested within the second heat-absorbing coil 203, which is nested within the second heat-transfer coil 209, and the second heat-transfer coil 209 is nested within the first heat-absorbing coil 201, as shown by the dashed arrow. Therefore, the first, second, and third heat-absorbing coils 201, 203, and 205 are in thermal communication with the first and second heat-transfer coils 207 and 209. In a preferred embodiment, the outer diameter of the first heat absorption coil is approximately 6 inches, but of course, the size of the HEEC can vary depending on design requirements.

[0027] Still referencing Figure 2The functional concept of the device will now be described. In this figure, fluid flow is indicated by solid arrows. Recycled refrigerant is supplied in vapor form at inlet 114 via a pump or compressor (not shown). The recycled refrigerant enters the first heat transfer coil 207 and is discharged from coil 207 through heat transfer coil discharge line 216. Simultaneously, subcooled refrigerant is drawn through the third absorber coil 205 and the second absorber coil 203. Since the second and third absorber coils 203, 205 are in thermal communication with the first heat transfer coil 207, heat from the recycled refrigerant is transferred to the subcooled refrigerant flowing through absorber coils 203, 205, as indicated by arrow "Q". The recycled refrigerant is discharged from the first heat transfer coil 207 through discharge line 216 and enters the second heat transfer coil 209 at suction line 218.

[0028] As the recovered refrigerant flows through the second heat transfer coil 209, the subcooled refrigerant flows through both the first and second heat absorption coils 201 and 203. Since the first and second heat absorption coils 201 and 203 are thermally connected to the second heat transfer coil 209, heat from the recovered refrigerant is transferred to the subcooled refrigerant flowing through the heat absorption coils 201 and 203, as indicated by arrow "Q". As a result, the recovered refrigerant is subcooled to a lower pressure and temperature and discharged from the subcooled refrigerant outlet 116.

[0029] Those skilled in the art will understand that the device configured as described above provides a consistent 34°F cooling to the refrigerant being recovered. This contrasts with devices available on the market today, providing this stable cooling regardless of ambient temperature and cooling unevenness.

[0030] Although specific embodiments have been described, it should be understood that any invention described herein is not limited thereto, as modifications can be made by those skilled in the art, particularly in light of the foregoing teachings. Therefore, the appended claims are intended to cover any such modifications that incorporate those features or improvements that embody the spirit and scope of the invention.

Claims

1. A refrigerant cooling device, comprising: A housing having a heat outlet and a return air inlet; An internal refrigeration circuit enclosed within the housing, the internal refrigeration circuit comprising a first heat-absorbing coil, a second heat-absorbing coil, and a third heat-absorbing coil; An inlet extending from the housing is used to receive the recycled refrigerant to be processed; The first heat transfer coil is enclosed in the housing and fluidly connected to the inlet. The first heat transfer coil is thermally connected to the third heat absorption coil and the second heat absorption coil. The second heat transfer coil is enclosed in the housing and is in fluid communication with the first heat transfer coil. The second heat transfer coil is in thermal communication with the first heat absorption coil and the second heat absorption coil. as well as A subcooled refrigerant outlet extends from the housing and is in fluid communication with the second heat transfer coil.

2. The refrigerant cooling device according to claim 1, wherein, The third heat absorption coil is concentrically nested inside the first heat transfer coil.

3. The refrigerant cooling device according to claim 2, wherein, The first heat transfer coil is concentrically nested inside the second heat absorption coil.

4. The refrigerant cooling device according to claim 3, wherein, The second heat absorption coil is concentrically nested inside the second heat transfer coil.

5. The refrigerant cooling device according to claim 4, wherein, The second heat transfer coil is concentrically nested inside the first heat absorption coil.

6. The refrigerant cooling device according to claim 1, wherein, The third heat-absorbing coil is concentrically nested within the first heat-transfer coil, the first heat-transfer coil is concentrically nested within the second heat-absorbing coil, the second heat-absorbing coil is concentrically nested within the second heat-transfer coil, and the second heat-transfer coil is concentrically nested within the first heat-absorbing coil.

7. The refrigerant cooling device according to claim 6, wherein, The capacity of the internal cooling circuit is approximately 4000 BTU.

8. The refrigerant cooling device according to claim 7, wherein, The temperature of the heat absorption coil is maintained at approximately 34°F.

9. An apparatus comprising: Housing, the housing comprising: A compressor used to pressurize cooling refrigerant; A condenser in fluid communication with the compressor is used to remove heat from the cooling refrigerant; and A heat exchange evaporator coil for absorbing heat from the recovered refrigerant, the evaporator coil including a plurality of heat-absorbing coils in fluid communication with the condenser and the compressor, and a plurality of heat-transfer coils for conveying the recovered refrigerant, the plurality of heat-transfer coils being thermally connected to the plurality of heat-absorbing coils.

10. The apparatus according to claim 9, wherein, The plurality of heat-absorbing coils are a first heat-absorbing coil, a second heat-absorbing coil, and a third heat-absorbing coil, and the plurality of heat-transfer coils are a first heat-transfer coil and a second heat-transfer coil.

11. The apparatus of claim 10, further comprising a metering device in fluid communication with the condenser and configured to dispense cooling refrigerant into each of the first, second, and third heat-absorbing coils.

12. The apparatus according to claim 11, wherein, The third heat-absorbing coil is concentrically nested within the first heat-transfer coil, the first heat-transfer coil is concentrically nested within the second heat-absorbing coil, the second heat-absorbing coil is concentrically nested within the second heat-transfer coil, and the second heat-transfer coil is concentrically nested within the first heat-absorbing coil.

13. The apparatus according to claim 9, wherein, The housing includes an internal cooling circuit with a capacity of approximately 4000 BTU.

14. The apparatus according to claim 13, wherein, The temperature of the heat absorption coil is maintained at approximately 34°F.

15. A method for recovering refrigerant from a refrigeration system, the method comprising the following steps: High-temperature and high-pressure refrigerant is supplied to the first heat transfer coil and the second heat transfer coil. The first heat transfer coil and the second heat transfer coil are thermally connected to the first heat absorption coil, the second heat absorption coil and the third heat absorption coil. The first heat absorption coil, the second heat absorption coil and the third heat absorption coil are components of a closed-loop refrigeration circuit enclosed in the shell. The refrigeration circuit supplies cooling refrigerant to the first, second, and third heat-absorbing coils; and Cooled and depressurized refrigerant is discharged from the second heat transfer coil.

16. The method according to claim 15, wherein, The housing includes an internal cooling circuit with a capacity of approximately 4000 BTU.

17. The method according to claim 15, wherein, The temperature of the heat absorption coil is maintained at approximately 34°F.

18. The method according to claim 15, wherein, The third heat-absorbing coil is concentrically nested within the first heat-transfer coil, the first heat-transfer coil is concentrically nested within the second heat-absorbing coil, the second heat-absorbing coil is concentrically nested within the second heat-transfer coil, and the second heat-transfer coil is concentrically nested within the first heat-absorbing coil.

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