PORTABLE SUBCOOLER FOR REFRIGERANT RECOVERY AND METHOD

Description

BACKGROUND

Field

The present disclosure relates generally to refrigeration, and, particularly to refrigerant recovery, and more particularly to subcooling refrigerant for recovery.

Description of the Problem and Related Art

Recovering refrigerant from refrigeration systems or heating, ventilation, and air conditioning (“HVAC”) systems is an essential part of servicing or decommissioning these systems to prevent environmental harm and ensure compliance with regulations. Federal regulations in many countries, including the United States, require that refrigerants be recycled or reclaimed whenever possible to minimize environmental impact. The U.S. Environmental Protection Agency (EPA) has regulations under Section 608 of the Clean Air Act that govern the handling, recycling, and disposal of refrigerants used in stationary refrigeration and air conditioning systems. These regulations require that refrigerants be recovered and recycled to industry standards before being reused in the same equipment or another system. 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 certified by the EPA to ensure it meets specific standards for handling refrigerants safely and efficiently. Additionally, technicians who work with refrigerants must be certified by the EPA to handle and work with these substances legally. By recycling or reclaiming refrigerants, HVAC professionals can help protect the environment and comply with federal regulations designed to mitigate the impact of refrigerants on the Earth's atmosphere.

Section 608 of the Clean Air Act also prohibits the knowing release of refrigerant during the maintenance, service, repair, or disposal of air-conditioning (AC) and refrigeration equipment. Additionally, according to Section 608, refrigerant must be recovered in its pure form, without mixing with other substances, and in a manner that does not vent it into the atmosphere. In practice, recovering refrigerant in its liquid form is often preferred because it is easier to handle and store. Additionally, recovering refrigerant as a liquid can help prevent the release of refrigerant vapor into the atmosphere, which is important for environmental and safety reasons. While recovering refrigerant in its liquid state is not explicitly required by Section 608, it is generally considered a best practice in the HVAC industry to recover refrigerant in its pure form and to minimize the release of refrigerant into the atmosphere.

When drawing refrigerant to be recovered from a refrigeration system, the substance is often at its saturation temperature, i.e., it is in a state of equilibrium between its liquid and vapor phases. Therefore, to minimize the risk of releasing refrigerant vapor into the atmosphere, the refrigerant is subcooled during extraction. Subcooling is a process used in the refrigeration cycle to lower the temperature of the refrigerant below its saturation temperature. This process of subcooling helps to ensure that the refrigerant remains in a liquid state and is free of any vapor when it is stored for reuse or disposal.

Some refrigerant recovery machines, which typically comprise a compressor or pump, may have built-in subcoolers or other cooling mechanisms to help lower the temperature of the recovered refrigerant. However, not all recovery machines include this feature, as it depends on the specific design and intended use of the machine. One example of a refrigerant recovery machine that includes a subcooler is the Appion® G5Twin Twin Cylinder Recovery Unit. This recovery unit features a built-in subcooler that attempts to ensure the recovered refrigerant is in a liquid state and free of any vapor before being transferred to a storage cylinder. 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 state for reuse or recycling.

However, these systems may still require additional subcooling of the evacuated refrigerant. Coolant being evacuated from the system being serviced is at a high temperature and high pressure. High ambient temperatures can reduce the efficiency of the refrigerant recovery machine, as the pump has to work harder to achieve the same level of refrigerant recovery. This can lead to longer recovery times and increased energy consumption, in addition to increasing maintenance costs for the recovery machine. Moreover, elevated storage tank pressures can occur when the recovery machine is operating in a high-temperature environment. The discharge pressure of the recovery machine while recovering refrigerants varies between 200-375 psi as the tank is being filled to its stated capacity without using a subcooling device. Operating in high ambient temperatures can increase the pressure of the recovered refrigerant in the storage tank, which may exceed the tank's rated pressure capacity. This can pose a safety risk and may require additional precautions to prevent over-pressurization. Elevated tank pressures can also reduce the rate of refrigerant recovery, as the higher pressure in the tank can oppose the flow of refrigerant from the system being serviced to the recovery machine. This can result in longer recovery times and increased energy consumption.

New synthetic refrigerants (R410a) that comprise components of the chlorine atom in the refrigerant makeup tend to expand at a higher rate of pressure than the original organic refrigerants. As of 2025 R410A and 134A will start being phased out. The new replacement refrigerants will be classified as A2L, meaning they will have A2L flammability rating with a lower critical pressure point. A new refrigerant, R1234YF, has a lower critical pressure rating (490 psi) than the current R410A at (709 psi) resulting in a greater need for a device that provides a consistent mechanical subcooling of recovered refrigerants.

To address this shortcoming, a “molecular transformator,” is often used to further cool the refrigerant prior to porting it into a storage tank. The molecular transformator, offered by CPS Products, Inc., as the Pro-Set® MT69, is essentially an auxiliary subcooler that alters the molecular structure of the evacuated coolant intended to facilitate condensing the coolant into to liquid form. It is inserted into the recovery process between the recovery machine and the storage tank. The device is submerged in an ice bath as the cooling medium. This is intended to help speed recovery time by keeping the refrigerant in a low-temperature/low-pressure state as it enters the tank. The discharge pressure can be reduced by 40% by utilizing a subcooling device.

However, the temperature of the ice bath is not consistent, especially during high ambient temperatures. Coolant coursing through the device may still be at a high temperature/pressure because it has not been subcooled properly in the recovery machine. This causes the ice to melt rapidly requiring constant resupply of ice to the ice bath, meaning greater cost in terms of money (for the ice) and time in man-hours. Consequently, the temperature of the ice bath can vary from 36° F. to 56° F., which in turn causes variability in the temperature and pressure of the recovery refrigerant.

An apparatus and method are needed to address these shortcomings and provided consistent subcooling of evacuated refrigerant to increase the efficiency and safety of the process while minimizing or eliminating the risk of release of greenhouse gas emissions.

SUMMARY

For purposes of summary, certain aspects, advantages, and novel features are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment. Thus, the apparatuses or methods claimed may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

A portable subcooling apparatus includes a housing within which is enclosed a compressor for pressurizing cooling refrigerant and a condenser in fluid communication with the compressor for removing heat from the cooling refrigerant, and a heat exchanging evaporator coil for absorbing heat from a recovery refrigerant, the evaporator coil comprising a plurality of heat absorption coils in fluid communication with the condenser and the compressor, and a plurality of heat transfer coils for conveying that recovery refrigerant, the plurality of heat transfer coils being thermally connected to the plurality of heat absorption coils.

In one aspect, the heat exchanging evaporator coil comprises first, second and third heat absorption coils and first and second heat transfer coils where the third heat absorption coil is concentrically nested within the first heat transfer coil, the first heat transfer coil is concentrically nested within the second heat absorption coil, the second heat absorption coil is concentrically nested within the second heat transfer coil, and the second heat transfer coil is concentrically nested within the first heat absorption coil.

A method for refrigerant recovery with the disclosed apparatus comprises the steps of providing high temperature and high pressure refrigerant to first and second heat transfer coils which are thermally connected to first, second, and third heat absorption coils, the first, second, and third heat absorption coils being a component of a closed loop refrigeration circuit enclosed within a housing, then providing cooling refrigerant to the first, second, and third heat absorption coils via the refrigeration circuit, and, finally, evacuating cooled and depressurized refrigerant from the second heat transfer coil.

BRIEF DESCRIPTION OF THE DRAWINGS

The apparatus is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.

FIG. 1 is a functional schematic of an exemplary refrigerant cooling apparatus according to an embodiment;

FIG. 2 is an illustration of the apparatus of FIG. 1 showing the evaporator coils in greater detail; and

DETAILED DESCRIPTION

The various embodiments of the sleep surface and their advantages are best understood by referring to FIGS. 1 and 2 of the drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the novel features and principles of operation. Throughout the drawings, like numerals are used for like and corresponding parts of the various drawings.

Furthermore, reference in the specification to “an embodiment,” “one embodiment,” “various embodiments,” or any variant thereof means that a particular feature or aspect described in conjunction with the particular embodiment is included in at least one embodiment. Thus, the appearance of the phrases “in one embodiment,” “in another embodiment,” or variations thereof in various places throughout the specification are not necessarily all referring to its respective embodiment.

FIG. 1 is a functional schematic of a refrigerant cooling apparatus 100 comprising a power supply 109 operative to provide suitable power 102 to a compressor 103 and a fan motor 107 which drives a fan 113. Power for compressor 103 and fan motor 107 may be 120 V from an external source. Compressor 103 moves subcooling refrigerant through the refrigeration circuit as will be described below. Compressor 103 is any compression device suitable for a 4000 BTU circuit. Preferably, compressor 103 is a non-spark-generating, rotary style compressor.

Cooling apparatus 100 further comprises a condenser 105 in fluid communication with compressor 103. A heat exchanging evaporator coil (HEEC) 101 is in fluid communication with condenser 105 with a filter drier 111 interposed between them. Apparatus 100 includes a housing 115 which encloses the above-described elements. Housing 115 is configured with a heat rejection outlet 117 and a return air inlet 119. Condenser 105 may, for example, comprise one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes across flow path to the heat rejection outlet 117. Condenser 105 may be a three-coil condenser rated for a 4000 BTU refrigeration circuit. Fan motor 107 is also preferably non-spark-generating. Fan 113 is operative to pass air, typically ambient air, across the tubes of condenser 105 to cool refrigerant vapor passing through the tubes.

In operation, subcooling refrigerant is drawn by compressor 103 through suction line 110 and discharged to condenser via compressor discharge line 104. Meanwhile, fan 113, driven by motor 107 impels cooling air through condenser 105 thereby removing heat from subcooling refrigerant coursing through condenser 105. Rejected heat 118 is expelled through heat outlet 117. Subcooling refrigerant becomes a liquid in condenser 105 and is drawn from condenser 105 through condenser discharge line 106 and flows through filter drier 111 which removes excess moisture, contaminants, and acid from the subcooling refrigerant. Drier 111 may be a charging drier, also known as a liquid line filter drier.

Subcooling refrigerant is then provided to HEEC 101 via evaporator supply line 112 for heat absorption. Meanwhile, recovery refrigerant, i.e., refrigerant to be recovered from a refrigeration system being serviced, is provided to HEEC 101 via recovery refrigerant inlet 114. Recovery refrigerant is cooled and is discharged via subcooled refrigerant outlet 116. At the same time return air 120 is drawn through return air inlet 119. Pressures high side may range from about 285 to about 305 psi and the low side from about 100 to about 120 psi depending on ambient load.

FIG. 2 presents a more detailed view of HEEC 101 within apparatus 100. Housing 115 and fan 113 are not shown for the sake of clarity. HEEC 101 comprises distributor 211 in the incoming supply line 112 which extends from drier 111. First, second, and third, capillary tubes 202, 204, 206 branch off from distributor 211. It will be appreciated that distributor 211 along with drier 111 comprise a metering device 213.

First capillary tube 202 extends from distributor 211 to first heat absorption coil 201 which includes first heat absorption coil discharge line 208. Second capillary tube 204 extends from distributor 211 to second heat absorption coil 203, which includes second heat absorption coil discharge line 210. Lastly, third capillary tube 206 extends from distributor 211 to third heat absorption coil 205 which includes third heat absorption coil discharge line 212. Coil discharge lines 208, 210, 212 are in fluid communication with HEEC return line 214 which exits HEEC 101 as compressor suction line 110. It should be noted condenser discharge line 106 and suction line 110 are preferably configured with service ports 108a, b. Accordingly, heat absorption coils 201, 203, 205 comprise an internal, closed loop refrigeration circuit along with compressor 103 and condenser 105.

HEEC 101 also comprises a first heat transfer coil 207 receiving recovery refrigerant from inlet 114 from an external source and having a first transfer coil discharge 216. Coil discharge 216 is in fluid communication with an intake line 218 for second heat transfer coil 209 which has a second transfer coil discharge 220 in fluid communication with subcooled refrigerant outlet 116. Inlet 114 and outlet 116 may be HVAC standard ¼″ fittings.

Third heat absorption coil 205 is configured with an outside diameter smaller than the inside diameter of first heat transfer coil 207 which has an outside diameter less than the inside diameter of second heat absorption coil 203. Second heat absorption coil 203 has an outside diameter less than the inside diameter of second heat transfer coil 209. Finally, second heat transfer coil 209 is configured with an outside diameter less than the inside diameter of the first heat absorption coil 201. As such, third heat absorption coil 205 is concentrically nested within first heat transfer coil 207, which is nested in second heat absorption coil 203, which is nested within second heat transfer coil 209, which, in turn, is nested within first heat absorption coil 201, as indicated by dashed arrows. Consequently, first, second, and third heat absorption coils 201, 203, 205 are in thermal communication with first and second heat transfer coils 207, 209. In a preferred embodiment, the outside diameter of the first heat absorption coil is about 6 inches, however, of course, size of the HEEC may vary depending on design needs.

Still referring to FIG. 2, the functional concepts of the apparatus will now be described. In the figure, flow of fluid is indicated by the solid arrows. Recovery refrigerant is provided as a vapor at inlet 114, by a pump or compressor (not shown). Recovery refrigerant enters first heat transfer coil 207 and is discharged from coil 207 through transfer coil discharge line 216. At the same time, subcooling refrigerant is being drawn through third heat absorption coil 205 and second heat absorption coil 203. Since second and third heat absorption coils 203, 205 are in thermal communication with first heat transfer coil 207, heat from recovery refrigerant is transferred to the subcooling refrigerant flowing through the heat absorption coils 203, 205, as indicated by the arrows “Q.” Recovery refrigerant is discharged from first heat transfer coil 207 through discharge line 216 and enters second heat transfer coil 209 at intake line 218.

As recovery refrigerant flows through second heat transfer coil 209, subcooling refrigerant flows through both first and second heat absorption coils 201, 203. Since first and second heat absorption coils 201, 203 are in thermal communication with second heat transfer coil 209, heat from recovery refrigerant is transferred to the subcooling refrigerant flowing through the heat absorption coils 201, 203, as indicated by the arrows “Q.” As a consequence, recovery refrigerant is subcooled to lower pressure and temperature and discharges at subcooled refrigerant outlet 116.

It will be appreciated by those skilled in the relevant arts that the apparatus, configured as described above, provides consistent cooling at 34° F. of refrigerant being recovered. This is in contrast to the devices currently available on the market today. This steady cooling is provided irrespective of ambient temperature and inconsistent cooling.

While particular embodiments have been described, it will be understood, however, that any invention appertaining to the apparatus described is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover any such modifications that incorporate those features or those improvements that embody the spirit and scope of the invention.