DX SYSTEM INTERIOR HEAT EXCHANGER DEFROST DESIGN FOR HEAT TO COOL MODE

Field of the Disclosure

[0001] This disclosure generally relates to geothermal direct exchange ("DX") heating/cooling systems, which are also commonly referred to as "direct expansion" heating/cooling systems. More particularly, this disclosure relates to means for resolving potential icing/frosting of an interior heat exchanger when the system is switched from a heating mode to a cooling mode.

Background of the Disclosure

[0002] Geothermal ground source/water source heat exchange systems typically utilize fluid-filled closed loops of tubing buried in the ground, or submerged in a body of water, so as to either absorb heat from, or to reject heat into, the naturally occurring geothermal mass and/or water surrounding the buried or submerged fluid transport tubing. The tubing loop is extended to the surface and is then used to circulate one of the naturally warmed and naturally cooled fluid to an interior air heat exchange means.

[0003] Common and older design geothermal water-source heating/cooling systems typically circulate, via a water pump, a fluid comprised of water, or water with anti-freeze, in plastic (typically polyethylene) underground geothermal tubing so as to transfer geothermal heat to or from the ground in a first heat exchange step. Via a second heat exchange step, a refrigerant heat pump system is utilized to transfer heat to or from the water. Finally, via a third heat exchange step, an interior air handler (comprised of finned tubing and a fan) is utilized to transfer heat to or from the refrigerant to heat or cool interior air space.

[0004] Newer design geothermal DX heat exchange systems, where the refrigerant fluid transport lines are placed directly in the sub-surface ground and/or water, typically circulate a refrigerant fluid, such as R-22, R-407C, R-410a, or the like, in sub-surface refrigerant lines, typically comprised of copper tubing, to transfer geothermal heat to or from the sub-surface elements via a first heat exchange step. DX systems only require a second heat exchange step to transfer heat to or from the interior air space, typically by means of an interior air handler. Consequently, DX systems are generally more efficient than water-source systems because less heat exchange steps are required and because no water pump energy expenditure is necessary. Further, since copper is a better heat conductor than most plastics, and since the refrigerant fluid circulating within the copper tubing of a DX system generally has a greater

temperature differential with the surrounding ground than the water circulating within the plastic tubing of a water-source system, generally, less excavation and drilling is required, and installation costs are lower, with a DX system than with a water-source system.

[0005] While most in-ground/in-water DX heat exchange designs are feasible, various improvements have been developed intended to enhance overall system operational efficiencies. Several such design improvements, particularly in direct expansion/direct exchange geothermal heat pump systems, are taught in U.S. Patent No. 5,623,986 to Wiggs; in U.S. Patent No. 5,816,314 to Wiggs, et al.; in U.S. Patent No. 5,946,928 to Wiggs; and in U.S. Patent No. 6,615,601 Bl to Wiggs, the disclosures of which are incorporated herein by reference. Such disclosures encompass both horizontally and vertically oriented sub-surface heat geothermal heat exchange means.

Summary of the Disclosure

[0006] Techniques and designs are disclosed to enhance and improve at least one of the efficiency, the longevity, and the interior comfort levels of a DX system when switching from the heating mode to the cooling mode, when refrigerant temperatures within the interior refrigerant heat exchange tubing is at a freezing, or lower, temperature.

[0007] More specifically, an improved means is provided for operating DX systems switching from the heating mode to the cooling mode at the end of a heating season when the ground is cold and the refrigerant within the interior heat exchanger is at a temperature at or below freezing, which may make it difficult to obtain full design refrigerant flow and which may "frost" the interior heat exchange refrigerant transport tubing, thereby ultimately resulting in a decrease in system operational efficiencies. Additionally, a means is disclosed for providing full or near full refrigerant flow. Still further, a means for preventing "frosting" of the interior refrigerant transport heat exchange tubing in a DX system when changing from the heating mode to the cooling mode is described herein.

[0008] All heat pump systems use expansion devices in the heating and cooling modes. Typical expansion devices include fixed orifice pin restrictors and automatic, self-adjusting expansion devices, which automatic devices are commonly referred to as "TXVs", or "TEVs." Expansion devices lower the pressure and temperature of the circulating refrigerant fluid so as to increase the ability of the fluid to absorb heat via providing a greater temperature differential. In DX systems, a unique problem is encountered in moderate to cold climates when switching from the heating mode to the cooling mode at the end of a

heating season. Namely, testing has shown that the ground immediately surrounding the subsurface, heat transfer, refrigerant transport tubing is sometimes very cold (at or below approximately 50 degrees Fahrenheit, or "F"), and the heat transfer fluid (a refrigerant) circulating within the tubing can exit the ground at temperatures at or below approximately 50 degrees F, which nearby surrounding ground has had heat removed all winter.

[0009] When the refrigerant exiting the ground is at temperatures at, or below, approximately 50 degrees F, as the refrigerant travels through an expansion device in the cooling mode, the refrigerant can potentially drop to a freezing temperature of 32 degrees F, or lower, which can result in "frosting" of the interior heat exchange refrigerant tubing. Such frosting results from humidity in the air being attracted via the cold temperatures and then condensing and freezing on the refrigerant transport heat exchange tubing. Such frosting (ice) can significantly reduce interior heat exchange abilities until the refrigerant exiting the ground has sufficiently warmed, via the ground absorbing waste heat rejected in the cooling mode, or via the ground naturally warming, to a point typically above approximately 50 degrees F, typically plus or minus about 5 degrees F. Further, when the ground is very cold (near or below approximately 50 degrees F), the refrigerant in the sub-surface heat exchanger tends to want to "stay" in the coldest area, thereby increasing the difficulty of obtaining design refrigerant flow rates for optimum system performance.

[0010] Thus, supplemental heat may be provided to the interior heat exchange means in such situations, so as to at least one of help melt any frosting/ice within the interior heat exchange means and to help provide/maintain a higher compressor discharge heat level to the sub-surface environment so as to hasten the system's ability to warm the cold sub-surface environment to a temperature within a normal cooling mode operational temperature range. Such supplemental heat may be supplied via at least one of an external heat source (such as a fossil fuel, electric, solar, or the like, heat supply means) and by an internal system heat source, such as heat from the high pressure/warm refrigerant side of the heat pump system. Heat from the high pressure side of the system could come from at least one of the high pressure and warm refrigerant fluid exiting the interior heat exchanger and from the hot gas vapor refrigerant exiting at least one of the compressor (which is depicted in the drawing herein) and the oil separator (if there is an oil separator, which is well understood by those skilled in the art).

[0011] Extensive testing has demonstrated that simply supplying supplemental heat, however, is not alone the answer, as supplying either too little heat or too much heat are both

inefficient. If one supplies too little supplemental heat, frosting of the interior heat exchange tubing and excessively low-pressure suction operational conditions persist. On the other hand, if one supplies too much heat, the ability to effectively cool the interior air or liquid is impaired or lost, since optimum or adequate heat exchange temperature differential is lost, and the compressor's working temperature can increase to an unsafe level, potentially resulting in compressor shut down or burnout.

[0012] Therefore, a means of supplying the appropriate amount of supplemental heat to the refrigerant transport tubing within the interior heat exchanger may incorporate at least one of a temperature and a pressure sensing device that engages the supplemental heat supply when the temperature of the refrigerant within the interior heat exchanger/air handler is at or below freezing, and that disengages the supplemental heat supply when the temperature of the refrigerant exiting the ground reaches about 50 degrees F. Further, such a supplemental heat means may engage so as to keep the temperature of the refrigerant entering the interior of the interior heat exchanger (typically an air handler) at a temperature level that is at least approximately 1 degree F above freezing, prior to the supplemental heat means (such as a special hot gas by-pass valve) disengaging when the temperature of the refrigerant exiting the ground reaches about 50 degrees F. Otherwise, the compressor's suction line superheat and/or the compressor's discharge hot gas temperature can become too high.

[0013] In such a design, the supplemental heat may be provided at one of two points. A first point is in the liquid refrigerant transport line past the cooling mode expansion device, but prior to the refrigerant actually entering the interior heat exchanger/air handler refrigerant transport tubing (which would typically be at a point immediately prior to the liquid refrigerant tubing distributor to the interior heat exchanger). A second point would be at a point in the vapor refrigerant transport line exiting the air handler, but prior to the refrigerant entering the system's accumulator and compressor.

[0014] Such supplemental heat may be supplied via a valve that automatically opens to permit at least one of hot gas/vapor refrigerant from the system's compressor and warm refrigerant fluid exiting the system's interior heat exchanger to provide supplemental heat to the refrigerant at least one of the said two points, entering and exiting the interior heat exchanger/air handler, and that automatically closes when the temperature of the refrigerant exiting the sub-surface geology reaches approximately 50 degrees F. Supplemental heat from the hot gas refrigerant is may having a higher temperature delta than heat from the interior heat exchanger, and therefore may be preferable in some applications.

[0015] Supplemental heat may be supplied to the refrigerant exiting the interior heat exchanger, but at a point before the accumulator, by a hot gas by-pass valve because such supplemental heat increases the back pressure and temperature of the refrigerant itself within the interior heat exchanger, which, in turn, when the supplemental heat is properly controlled, maintains the temperature of the refrigerant within the interior heat exchanger at a point above freezing, thereby eliminating the frosting problem. Such a supplemental hot gas bypass valve heating means is well known in the refrigeration art field, where hot gas by-pass valves routinely supply small portions of hot gas to refrigerant lines exiting heat exchangers so as to provide back pressure and eliminate frosting on freezers. Such hot gas by-pass valves, as an example, are manufactured by the Sporlan Division of the Parker Hannifin Corporation, of 206 Lange Drive, Washington, MO.

[0016] However, such hot gas by-pass valves alone will not provide both optimal combined increased refrigerant flow abilities when the ground is cold (at or below about 50 degrees F) and interior heat exchanger defrosting abilities in a DX system. Further, such hot gas by-pass valves alone, absent special pressure settings for a DX system application (heretofore unknown prior to extensive testing conducted by Wiggs), will not optimize results. To optimize unique results when one switches from the heating mode to the cooling mode in a DX system, such valves may have special and specific pressure settings and may be used in conjunction with an expansion device by-pass means, comprised of at least one of a TXV by-pass line and a TXV bleed port, when TXVs, or when other expansion devices (such as pin restrictors, or the like), are used as the cooling mode expansion device for the interior heat exchanger. Since TXVs are very common cooling mode expansion devices, they will be discussed and shown herein as an example.

[0017] The drawings herein depict supplemental heat supplied to the interior heat exchange means (herein depicted as an air handler) from a smaller secondary refrigerant hot gas line exiting the primary hot gas discharge line side of the system. The smaller secondary hot gas line exits the high pressure side of the DX system at a point past the system's compressor and oil separator, if there is an oil separator, but before the hot gas travels into the sub-surface heat exchange tubing (the condenser in the cooling mode). The automatic hot gas by-pass valve disclosed herein may be provided with hot gas exiting an oil separator, and an oil separator that is at least 98% efficient may be incorporated into the system design. Such an arrangement avoids sending hot gas directly from the compressor into the automatic

valve, which may deliver too much oil and potentially impair the valve's best mode of operation.

[0018] In a DX system application, a common "TXV" cooling mode expansion device may lower the temperature of the refrigerant fluid entering the interior heat exchanger/air handler by approximately 10 to 20 degrees F. It would be well understood by those skilled in the art that differing expansion devices could have differing temperature drop ranges (and corresponding pressure drop ranges) other than a common approximate 10 to 20 degree F common temperature drop range. In such event, the problem addressed herein would apply to any situation were the refrigerant traveling into the interior air handler, or other heat exchange means, was at or below the freezing point.

[0019] Thus, a means of both more quickly increasing the refrigerant flow rate to a full design flow rate, when full design refrigerant flow is otherwise impaired because of a very cold sub-surface environment tending to "keep" the refrigerant in the coldest location, and increasing the temperature of the refrigerant within the interior heat exchanger (the interior heat exchanger is typically an air handler comprised of finned tubing, but may also be comprised of a refrigerant to water/liquid heat exchanger, or the like, all of which are well understood by those skilled in the art) to a point above freezing is desirable during such a heating to cooling mode transition period.

[0020] Proprietary testing has demonstrated that, in a DX system application, a specially designed hot gas by-pass valve may be used in conjunction with at least one of a TXV with a sufficiently sized bleed port, and a TXV with a specially designed and opened by-pass line around the TXV, when in the cooling mode of system operation at the beginning of a cooling season, when the sub-surface ground temperature is abnormally cold (at or below about 50 degrees F via heat being withdrawn throughout the winter), so as to both insure adequate refrigerant flow and to eliminate frosting within the interior heat exchanger during such a heating to cooling mode transitional time period. Both the specially designed hot gas by-pass valve and the specially designed TXV by-pass means may be utilized in conjunction with one another to simultaneously solve both problems unique to a DX system. The use of only one of the specially designed hot gas by-pass valve and the specially designed TXV by-pass means will not optimally address both the problems of inadequate refrigerant fluid flow from the sub-surface heat exchanger and interior heat exchanger frosting. Extensive testing has shown that both the specially designed hot gas by-pass valve and the specially designed TXV, with at least one of a bleed port and a by-pass means, may be used together to resolve

the unique problems encountered by a DX system application (when switching from the heating to the cooling mode, when the sub-surface geothermal heat exchanger is in a cold geology that is approximately 50 degrees F, or colder).

[0021] The hot refrigerant gas/vapor by-pass refrigerant transport line may have an interior diameter no greater than the size of the system's liquid refrigerant transport line between the compressor unit and the air handler. Such a liquid line is typically a 3/8 inch O.D., refrigerant grade, type L copper, line for 1 to 2-5 ton system designs, and a 1/2 inch O.D., refrigerant grade, type L copper, line for 2.6 to 5 ton system designs, for example. However, such a liquid line may be no smaller than half the size of the liquid refrigerant transport line size between the compressor and the interior air handler.

[0022] The automatic hot gas by-pass valve ("AV") may have/incorporate a pressure sensing cap and both a hot gas supply line and a pressure sensor/equalizer line (which cap, hot gas supply line, and equalizer line are all well understood by those skilled in the art, except that the cap pressure charge, as described herein for a DX system application, was not previously known) extending from the AV to a point that is at least approximately two inches, and in some applications at least approximately twelve inches, beyond the AVs hot gas supply point. (When the term "beyond" is used herein, it means past the referenced point in the direction of the refrigerant flow.) The AV valve's equalizer line senses at least one of the temperature and the pressure of the supplementally heated refrigerant fluid traveling at least one of into, and out of, the interior heat exchanger/air handler.

[0023] When the hot refrigerant gas/vapor by-pass line extends to, and operably connects with, the liquid refrigerant transport line at a point past the air handler's TXV, but before the liquid line distributor, when at least one of an R-410A and an R-407C refrigerant is utilized, an AV may be installed within the hot gas by-pass line that begins to close off the by-pass line when approximately 75 psi is reached within the equalizer line, and that modulates to fully close off the hot gas by-pass line at a point when approximately 95 psi is reached in the equalizer line. Such an AV may have a pressure sensitive cap filled with dry nitrogen gas at a pressure of approximately 85 psi, plus or minus approximately 5 psi, to offset the valve spring adjustment when the valve, if adjustable, is equivalent to the valve identified below, with the valve's adjustable screw/nut, at the below identified valve's base, screwed in fully clockwise. A suitable valve, but with approximately 85 psi of dry nitrogen in its pressure sensitive cap (which valve and cap and adjustable screw/nut are well understood by those skilled in the art), would be a Sporlan Valve HGBE-5-95/115, as manufactured by the

Sporlan Division of the Parker Hannifin Corporation, of 206 Lange Drive, Washington, MO 63090. Other valves may be utilized that have the same operational equivalencies.

[0024] Detailed testing has shown that if a cap pressure setting of approximately 85 psi (plus or minus approximately 5 psi) is higher (then being too high), there will be no cooling effect as too much hot gas is being sent through the interior heat exchanger (an air handler or the like), and both the compressor's superheat and discharge temperature will be too high. On the other hand, and if a cap pressure setting of about 85 psi (plus or minus approximately 5 psi) is lower (then being too low), too little refrigerant is permitted to by-pass the TXV so as to result in too much frosting/ice build-up within the interior heat exchanger, so as to inhibit heat exchange with the interior air, and too little refrigerant circulation occurs within the sub-surface geothermal heat exchange tubing.

[0025] However, testing has indicated that, when utilizing one of an R-41 OA refrigerant and an R407C refrigerant, when the hot refrigerant gas/vapor by-pass line extends to and operably connects with a supply point that is past the interior heat exchanger/air handler refrigerant's vapor line exit point, but before the accumulator, an AV may be installed within the hot gas by-pass line that begins to close off the by-pass line when approximately 90 psi is reached within the equalizer line, and that modulates to fully close off the by-pass line at a point when approximately 102 psi is reached in the equalizer line (which will be at the approximate point where the temperature of the refrigerant exiting the sub-surface geology/ground reaches about 50 degrees F). Such an AV may have a pressure sensitive cap filled with dry nitrogen gas at a pressure of approximately 110 psi to offset the valve spring adjustment when the valve, if adjustable, is equal, or equivalent, to the valve identified below, with the adjustable screw/nut at the base of the below identified valve example screwed in fully clockwise. A suitable valve, but with approximately 110 psi, of dry nitrogen in its pressure sensitive cap (which valve and cap and adjustable screw/nut are well understood by those skilled in the art), for example, would be a Sporlan Valve HGBE-5- 95/115, as manufactured by the Sporlan Division of the Parker Hannifin Corporation, of 206 Lange Drive, Washington, MO 63090. Other valves may be utilized that have the same operational equivalencies.

[0026] When a refrigerant other than R-41OA or R-407C is utilized, the psi pressure setting of the valve cap may need to be appropriately adjusted, so as to accomplish the same approximate results of keeping the interior of the air handler warm enough to prevent frosting, and so as to disengage the AV when the refrigerant temperature exiting the ground

reaches approximately 50 degrees F. Regardless of the location of the AV and regardless of refrigerant type, the AVs equalizer line (which equalizer line is well understood by those skilled in the art) may be at least approximately two, and in certain applications at least approximately twelve, inches downstream in the direction of the refrigerant flow from the AVs hot refrigerant gas input connection point into at least one of the refrigerant fluid entering the interior heat exchanger, and the refrigerant fluid exiting the interior heat exchanger.

[0027] In the alternative, at least one of an electronically operated valve, with predetermined settings, and a solenoid valve could be utilized in lieu of the automatically operating hot gas by-pass valve ("AV") described herein. However, at least one of an electronic valve and a solenoid valve may not always be preferable in that every electronic component added to a DX system complicates the system and provides added component failure risks, thereby potentially impairing the optimum durability of the DX system design. However, if at least one of an electronic valve and a solenoid valve were to be utilized for such hot-gas by-pass valve purpose, the respective valve settings may be designed to operate within the herein disclosed design parameters. Neither an electronic valve nor a solenoid valve is shown in detail herein, as same would be well understood by those skilled in the art.

[0028] The specially sized TXV by-pass means may be comprised of at least one of a TXV bleed port and a TXV by-pass line. A TXV bleed port is well understood by those skilled in the art, although the bleed port size for a DX system would have an equivalent refrigerant flow rate as herein described for a TXV by-pass line containing a pin restrictor, which TXV bleed port size, for use in conjunction with a specially sized hot gas by-pass valve for a DX system, is believed to have not been previously known or disclosed.

[0029] A TXV by-pass line, for use in conjunction with the above-described hot gas bypass automatic valve design, may be comprised of a refrigerant transport line of no larger a size than the system's liquid refrigerant transport line between the system's compressor and interior air handler, and no smaller than half that size, and may have a pin restrictor (or the equivalent thereof), within pin restrictor housing (pin restrictors and their housing are well understood by those skilled in the art), within the TXV by-pass line, which TXV by-pass line transports refrigerant fluid around the primary cooling mode TXV itself (although not around the TXVs capillary tube connection to the vapor line exiting the interior heat exchanger). The pin restrictor' rounded orifice, which orifice is within the center of the pin restrictor,

which pin restrictor is within the TXV by-pass line, may be sized as per the following formula:

[0030] A rounded orifice size, or the equivalent thereof, with an area of approximately 0.000082 inches per 1,000 BTUs of system compressor capacity size in BTUs, where 12,000 BTUs equal one ton of compressor capacity size (not system capacity size), plus or minus approximately 10%.

[0031] As it is well known that refrigerant flow rates through a pin restrictor orifice are somewhat different than through a TXV bleed port, the flow rate through a TXV bleed port may be designed to be approximately equal to the flow rate, as described in detail herein, for the desired flow rate through the orifice of a pin restrictor.

[0032] Thus, whenever the at least one of a bleed port through a TXV and a TXV by-pass line with a pin restrictor provides/comprises a passageway that allows of a flow of liquid refrigerant at least one of through and around the cooling mode expansion device (a TXV or other cooling mode expansion device), the passageway size may be the equivalent of an orifice/hole that is sized by multiplying approximately 0.000082 times the system design tonnage in thousands, where one ton equals 12,000 BTUs.

[0033] When a TXV bleed port is utilized for the TXV by-pass means, the hot gas supplied via the specially designed hot gas by-pass valve may be supplied automatically after the extra refrigerant fluid (the extra refrigerant fluid exiting the sub-surface heat exchanger and traveling through the bleed port in the TXV) has already been introduced into the refrigerant fluid traveling into the interior heat exchanger.

[0034] However, when a TXV by-pass line is utilized, in conjunction with the specially sized pin restrictor orifice, the extra refrigerant fluid (the extra refrigerant fluid exiting the sub-surface heat exchanger and traveling through the by-pass line around the TXV) may be introduced at least approximately two inches prior to the introduction of hot gas refrigerant supplied via the specially designed automatic hot gas by-pass valve.

[0035] Alternately, in lieu of utilizing a hot gas by-pass valve in conjunction with at least one of a TXV with a bleed port and a TXV with a by-pass line containing a pin restrictor with a specially sized internal orifice, testing has indicated a design that is potentially more advantageous. Namely, when the automatic hot gas by-pass valve, as disclosed herein, is used in conjunction with a TXV by-pass line (sized as disclosed herein), the TXV by-pass line may be left fully open, with no pin restrictor and with no other refrigerant flow

restriction whatsoever. Testing has shown that using the full by-pass line flow rate, the hot gas provided by the automatic hot gas valve is sufficiently tempered to keep most, or all, of the ice off the interior air handler's finned heat exchange tubing, while keeping both the compressor suction line superheat temperature lower and the compressor discharge temperature lower.

[0036] More specifically, testing has evidenced that full flow through the TXV, while not absolutely mandatory, keeps the superheat at the compressor (superheat at the compressor's suction line) about 6 degrees lower, and keeps the compressor discharge temperature about 10 degrees lower, than utilizing at least one of the TXV bleed port and the pin restrictor in the TXV by-pass line, as described hereinabove. Thus, full flow through the TXV by-pass line may improve operational efficiency, but may also require an extra valve to shut off the full flow once the refrigerant flow exiting the sub-surface heat exchanger reaches about 50 degrees F, which extra valve may, or may not, be worthwhile installing, depending on system design conditions. Such an extra valve may be comprised of a solenoid valve, a pressure sensitive cut-off valve, a temperature sensitive valve, or the like.

[0037] The other advantage of utilizing a temporary full refrigerant flow through the TXV by-pass line (without any restriction) is that the cooling mode air temperature differentials within the interior air handler are effected at a somewhat accelerated rate over, and are initially about several degrees greater than, that of a design utilizing at least one of a bleed port through a TXV, and a TXV with a TXV by-pass line with a pin restrictor in the by-pass line. Thus, for commercial system designs, for example, a full refrigerant flow through an unrestricted TXV by-pass line design, with an extra valve within the by-pass line to fully cut off the refrigerant flow within the by-pass line once the refrigerant exiting the ground reached a temperature of about 50 degrees F, may be provided.

[0038] As explained, in order to optimize normal system operational efficiencies in the cooling mode, when refrigerant temperatures exiting the ground have warmed up above the approximate 50 degree F range, the full and unrestricted TXV by-pass line needs to be closed. Closing the TXV by-pass line, after such conditions are reached, may be accomplished via at least one of a solenoid valve, a pressure valve, and a temperature valve, or the like, which are designed to fully block the flow of refrigerant through the TXV by-pass line when refrigerant temperatures, exiting the sub-surface environment in the cooling mode, exceed approximately 50 degrees F.

[0039] When using a TXV, with an unrestricted TXV by-pass line, in conjunction with a hot gas by-pass valve, as disclosed herein, testing has demonstrated the pressure setting in the hot gas by-pass valve's cap (when utilizing a valve such as the Sporlan design described above as an example) may be set at approximately 85 psi, plus or minus approximately 5 psi.

[0040] Further, whenever a hot gas by-pass valve is used in a DX reverse-cycle system, a safety check valve may be installed within the hot gas by-pass line so as to prevent any unwanted reverse direction refrigerant flow through any potential slight leak in the hot gas by-pass valve when the system is operating in the heating mode (with the refrigerant flowing in a reverse direction from that in the cooling mode), which otherwise could significantly impair system operational efficiencies. A safety check valve may be installed within the primary hot-gas by-pass valve's hot gas supply line to help prevent any such unwanted occurrence.

Brief Description of the Drawings

[0041] FIG. 1 is a side view of a partial DX geothermal heating/cooling system, primarily showing an interior air handler, refrigerant transport lines, and valves, incorporating primary automatic valve, TXV, and TXV by-pass line teachings of the present disclosures where hot gas is introduced into the liquid refrigerant transport line after the TXV, but before the liquid line distributor to the air handler.

[0042] FIG. 2 is a side view of a pin restrictor.

[0043] FIG. 3 is a side view of a partial DX geothermal heating/cooling system, primarily showing an interior air handler, refrigerant transport lines, and valves, incorporating primary automatic valve, TXV, and TXV by-pass line teachings of the present disclosures where hot gas is introduced into the warm vapor refrigerant transport line after the refrigerant has exited the air handler, but before the refrigerant is sent to the accumulator and compressor.

[0044] FIG. 4 is a side view of a compressor, an oil separator, and a hot gas by-pass valve, where the hot gas to the valve exits an oil separator.

Detailed Description

[0045] The following detailed description is of the best presently contemplated mode of carrying out the subject matter disclosed herein. The description is not intended in a limiting sense, and is made solely for the purpose of illustrating the general principles of this subject

matter. The various features and advantages of the present disclosure may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings.

[0046] Referring now to the drawings in detail, where like numerals refer to like parts or elements, there is shown in FIG. 1 a side view, not drawn to any scale, of an automatic self- adjusting hot gas by-pass valve 1 (also referred to as an "AV") that is situated in a smaller hot gas by-pass refrigerant transport line 2. The hot gas by-pass line 2 carries refrigerant (not shown herein except for refrigerant flow directional arrows 3) originating from the system's compressor (the compressor is not shown herein as compressors are well understood by those skilled in the art) to the automatic valve 1.

[0047] The size (not drawn to scale) of the hot gas by-pass line 2 is no larger than the liquid refrigerant transport line 5 size between the compressor (not shown) and the interior heat exchanger/air handler 6, and is no smaller than half the size of the liquid refrigerant transport line 5 size between the compressor (not shown) and the interior air handler 6.

[0048] A check valve 22 (shown here in an open position in the cooling mode of system operation) is shown as situated in the hot gas by-pass line 2 between the compressor (not shown) and the AV 1 , so as to provide a safety measure to prevent refrigerant flow through the hot gas by-pass line 2 when the system is operating in the heating mode, although the AV 1 itself would normally prevent such flow. Check valves 22 are well understood by those skilled in the art. In the cooling mode, the refrigerant 3 traveling through the hot gas by-pass line 2 travels through the AV 1, which automatically meters the flow of the hot gas for delivery, at a low pressure line delivery point 4 into the primary low pressure and cool liquid refrigerant transport line 5 entering the system's interior heat exchanger 6 (herein shown as an air handler 6, which air handler 6 is well understood by those skilled in the art).

[0049] Additionally, a common thermostatically controlled self-adjusting expansion valve 7 (also known as a "TEV" and a "TXV") is shown as situated within the primary cool liquid refrigerant transport line 7. In the cooling mode in a DX system design, the primary cool liquid refrigerant transport line 5 carries refrigerant 3 coming from the sub-surface heat exchanger (not shown herein as DX system sub-surface heat exchangers are well understood by those skilled in the art), which sub-surface heat exchanger acts as the condenser in the cooling mode. The cool liquid refrigerant transport line 5 carries cool liquid refrigerant 3 both to the TXV 7 and to a pin restrictor 13 situated within a cool liquid refrigerant by-pass

line 12. After passing through the TXV 7 and pin restrictor 13, the pressure and temperature of the refrigerant 3 within the cool refrigerant transport line 5 is reduced, and the refrigerant 3 is thereafter transported to an interior heat exchanger 6 by means of the continuing primary low pressure liquid refrigerant transport line 5. The refrigerant 3 picks up and gains waste heat within the interior heat exchanger 6, and is then transported out of the interior heat exchanger 6, by means of a primary warm vapor refrigerant transport line 9, to an accumulator (not shown) and to a compressor (not shown). Accumulators and compressors are well understood by those skilled in the art.

[0050] The TXV 7 has a TXV equalizer line 8, which is attached to, and senses the pressure in, the primary warm vapor refrigerant transport line 9 exiting the interior heat exchanger 6, as is well understood by those skilled in the art. The TXV 7 also has a temperature sensing bulb 10, which bulb 10 is also operably connected to the primary warm vapor refrigerant transport line 9 exiting the interior heat exchanger 6, via a connecting line 11 to the TXV 7, as is also well understood by those skilled in the art.

[0051] Here, however, a cool liquid refrigerant by-pass line 12 is shown by-passing and traveling around the TXV 7. The cool liquid refrigerant by-pass line 12 contains a pin restrictor 13 with a central orifice 14, which orifice 14 meters the refrigerant 3 flow through the cool liquid refrigerant by-pass line 12 around the TXV 7. The central orifice 14 within the pin restrictor 13 is sized so that the rounded orifice 14 size, or the equivalent thereof, has an area of approximately 0.000082 inches per 1,000 BTUs of system compressor capacity size in BTUs, where 12,000 BTUs equal one ton of compressor capacity size.

[0052] A TXV 7 can also be constructed with an internal bleed port (not shown, as same is well understood by those skilled in the art) that permits refrigerant 3 to continuously flow/bleed through the TXV 7. Whenever the at least one of a bleed port through a TXV 7 and a TXV by-pass line 12 with a pin restrictor 13 provides/comprises a passageway that allows of a flow of liquid refrigerant 3 at least one of through and around the cooling mode TXV 7 expansion device (an expansion device can be a TXV 7 or other cooling mode expansion device, as is well understood by those skilled in the art), the passageway size may be the equivalent of an orifice/hole 14 that is sized by multiplying approximately 0.000082 times the system design tonnage in thousands, where one ton equals 12,000 BTUs.

[0053] To keep compressor discharge temperatures lower and compressor superheat lower when the AV 1 is engaged, a TXV refrigerant transport by-pass line 12 may be provided that

permits full refrigerant 3 flow through the by-pass line 12 in an unobstructed manner. In such a system design, the pin restrictor 13 may be eliminated and a solenoid valve 27 may be used instead. In lieu of a solenoid valve 27, a pressure valve, a temperature valve, or the like, may be used so long as the refrigerant 3 flow through the by-pass line 12 was unrestricted when the AV 1 was engaged, and the refrigerant 3 flow through the by-pass line 12 was fully closed off when the AV 1 was disengaged (when the temperature of the refrigerant 3 exiting the sub-surface geology (not shown) was approximately fifty degrees F.

[0054] Here, both a pin restrictor 13 and a solenoid valve 27 are shown as optional alternatives. However, only one of the pin restrictor 13 and the solenoid valve 27 is typically used.

[0055] Referring again to the AV 1 , the AV 1 has an AV equalizer line 18 extending from the AV 1 to the primary low pressure liquid refrigerant transport line 5. Here, the AV 1 is shown as feeding hot refrigerant 3 gas into the primary low pressure liquid refrigerant transport line 5 at a low pressure delivery point 4 that is at least two inches (not drawn to scale) beyond both the TXV 7 and the cool liquid refrigerant by-pass line 12, that is at least two inches, and in some applications at least twelve inches, prior to the AV equalizer line entry point 19 into the primary low pressure liquid refrigerant transport line 5, and that is prior to the distributor 20 (distributors are well understood by those skilled in the art) to the interior heat exchanger/air handler 6. When the terms "beyond" and "prior to" are utilized herein, the terms are based upon refrigerant flow direction as indicated by arrows 3.

[0056] In such a design, where the hot gas by-pass line 2 has a low pressure liquid line delivery point 4 that is prior to the distributor 20 to the interior heat exchange means 6, a dry nitrogen pressure installation line 15 is shown for use in charging the cap 16 of the AV 1 with a specific dry nitrogen charge of approximately eighty-five psi, when one of an R-410A and an R-407C refrigerant 3 is utilized, to offset the valve spring adjustment (the spring is not shown but is well understood by those skilled in the art) when the AV 1 , if adjustable as is the valve identified below, is equivalent to the valve identified below with its adjustable screw/nut 17 in a fully clockwise position. A suitable adjustable AV 1, with its adjustable screw/nut 17 (which adjustable screw/nut 17 is well understood by those skilled in the art) in a fully clockwise position, but with an approximate eighty- five psi of dry nitrogen in its pressure sensitive cap 16 (which automatic valve ("AV") 1 and cap 16 are well understood by those skilled in the art), would be a Sporlan Valve HGBE-5-95/115, as manufactured by the

Sporlan Division of the Parker Hannifin Corporation, of 206 Lange Drive, Washington, MO 63090. Other valves may be utilized that have the same operational equivalencies.

[0057] The automatic hot gas by-pass valve/ AV 1 disclosed herein may be provided with hot refrigerant gas exiting an oil separator (not shown), after exiting the compressor (not shown) and an oil separator that is at least ninety-eight percent efficient may be incorporated into the system design. Compressors and oil separators are well understood by those skilled in the art.

[0058] Although not shown herein, an electronically controlled valve, which is well understood by those skilled in the art, could be substituted in lieu of the automatic hot gas bypass valve 1 , also referred to herein as the AV 1 , so long as the operative pressure settings disclosed herein are programmed in and utilized.

[0059] FIG. 2 is a side view of a common pin restrictor 13. As is well understood by those skilled in the art, a pin restrictor 13 commonly has a central orifice 14 and fins 21. The fins 21 and central orifice 14 both permit refrigerant flow around and through the pin restrictor 13 when the system is operating in a reverse mode, with the reverse mode herein being in a heating mode and not shown. A pin restrictor' s 13 housing is well understood by those skilled in the art and is not shown herein.

[0060] FIG. 3 is a side view, not drawn to scale, of an automatic self-adjusting hot gas bypass valve 1 (also referred to as an "AV") that is situated in a smaller hot gas by-pass refrigerant transport line 2. The hot gas by-pass line 2 carries refrigerant (not shown herein except for refrigerant flow directional arrows 3) originating from the system's compressor (not shown), through an oil separator to the AV 1.

[0061] The size (not drawn to scale) of the hot gas by-pass line 2 is no larger than the liquid refrigerant transport line 5 size between the compressor (not shown) and the interior heat exchanger/air handler 6, and is no smaller than half the size of the liquid refrigerant transport line 5 size between the compressor (not shown) and the interior air handler 6.

[0062] A check valve 22 (shown here in an open position) is shown as situated in the hot gas by-pass line 2 between the compressor (not shown) and the AV 1 , so as to provide a safety measure to prevent refrigerant 3 flow through the hot gas by-pass line 2 when the system is operating in the heating mode, although the AV 1 itself would normally prevent such flow. Check valves 22 are well understood by those skilled in the art.

[0063] In the cooling mode, the refrigerant 3 traveling through the hot gas by-pass line 2 travels through the AV 1, which automatically meters the flow of the hot gas refrigerant 3 for delivery, at a vapor line delivery point 27 into the primary warm vapor refrigerant transport line 9 exiting the system's interior heat exchanger 6 (herein shown as an air handler 6, which air handler 6 is well understood by those skilled in the art).

[0064] Additionally, a common thermostatically controlled self-adjusting expansion valve 7 (also known as a "TEV" and a "TXV"), is shown as situated within the primary cool liquid refrigerant transport line 5. In the cooling mode in a DX system design, the primary cool liquid refrigerant transport line 5 carries refrigerant coming from the sub-surface heat exchanger (not shown herein as DX system sub-surface heat exchangers are well understood by those skilled in the art), which sub-surface heat exchanger acts as the condenser in the cooling mode. The cool liquid refrigerant transport line 5 carries cool liquid refrigerant 3 both to the TXV 7 and to a pin restrictor 13 situated within a cool liquid refrigerant by-pass line 12. After passing through the TXV 7 and pin restrictor 13, the pressure and temperature of the refrigerant 3 within the cool liquid refrigerant transport line 5 is reduced, and the refrigerant 3 is thereafter transported to an interior heat exchanger 6 by means of a primary low pressure liquid refrigerant transport line 5. The refrigerant 3 gains heat within the interior heat exchanger 6, and is then transported out of the interior heat exchanger 6, by means of a primary warm vapor refrigerant transport line 9, to an accumulator (not shown) and to a compressor (not shown). Accumulators and compressors are well understood by those skilled in the art.

[0065] The TXV 7 has a TXV equalizer line 8, which is attached to, and senses the pressure within, the primary warm vapor refrigerant transport line 9 exiting the interior heat exchanger 6, as is well understood by those skilled in the art. The TXV 7 also has a temperature sensing bulb 10, which bulb 10 is also attached to, and senses the temperature within, the primary warm vapor refrigerant transport line 9 exiting the interior heat exchanger 6, which bulb 10 is operably connected via a connecting line 11 to the TXV 7, as is also well understood by those skilled in the art.

[0066] Here, however, a cool liquid refrigerant by-pass line 12 is shown by-passing and traveling around the TXV 7. The cool liquid refrigerant by-pass line 12 contains a pin restrictor 13 with a central orifice 14, which orifice 14 meters the refrigerant 3 flow through the cool liquid by-pass line 12 around the TXV 7. The central orifice 14 within the pin restrictor 13 is sized so that the rounded orifice 14 size, or the equivalent thereof, has an area

of approximately 0.000082 inches per 1,000 BTUs of system compressor capacity size in BTUs, where 12,000 BTUs equal one ton of compressor capacity size.

[0067] Referring again to the AV 1 , the AV 1 has an AV equalizer line 18 extending from the AV 1 to the primary warm vapor refrigerant transport line 9. Here, the AV 1 is shown as feeding hot refrigerant 3 gas into the primary warm vapor refrigerant transport line 9 at a vapor line delivery point 27 that is beyond the interior heat exchanger 6 and that is at least approximately two inches (and in some applications at least twelve inches) prior to (based upon refrigerant flow direction, as indicated by arrows 3) the AV equalizer line's 18 entry point 19 into the primary warm refrigerant transport line 9 that leads to the system's accumulator (not shown) and compressor (not shown). Accumulators and compressors are well understood by those skilled in the art and are not shown herein.

[0068] In such a design where the hot gas refrigerant 3 is supplied to refrigerant 3 exiting the interior heat exchanger/air handler 6, where the hot gas by-pass line 2 has a warm vapor refrigerant transport line 9 delivery point 27 that is subsequent to and beyond (based upon refrigerant flow direction as indicated by arrows 3) the interior heat exchange means 6, but prior to entry into the system's accumulator (not shown) and compressor (not shown), and where a TXV 7 has at least one of a TXV bleed port (a TXV bleed port is not shown as same is well understood by those skilled in the art) and a TXV by-pass line 12 containing a pin restrictor 13, with the bleed port and/or the pin restrictor 13 permitting only a specified amount of refrigerant 13 to pass through a certain sized opening/orifice 14 (as described above), the AVs 1 cap 16 may be specially charged with a certain pressure of dry nitrogen (not shown). A dry nitrogen pressure installation line 15 is shown for use in charging the cap 16 of the AV 1 with a specific dry nitrogen (not shown) charge of approximately one hundred ten psi, when at least one of an R-410A refrigerant and an R-407C refrigerant is utilized, so as to offset the valve spring adjustment (the spring is not shown but is well understood by those skilled in the art) when the AV 1 , if adjustable, is equal or equivalent to the valve identified below, with the adjustable screw/nut 17 at the base of the below identified valve example screwed in fully clockwise. As an example, a suitable adjustable AV 1, with the adjustable screw/nut 17 at the base of the below identified valve example screwed in fully clockwise, but with approximately one hundred ten psi of dry nitrogen in its pressure sensitive cap 16, would be a Sporlan Valve HGBE-5-95/115, as manufactured by the Sporlan Division of the Parker Hannifin Corporation, of 206 Lange Drive, Washington, MO 63090. Other valves, similar to the AV 1 described herein, may be utilized that have the same

operational equivalencies. In this particular design, the solenoid, or the like, valve 28, as also depicted in the by-pass line 12, would be eliminated.

[0069] Alternatively, in a design where the hot gas refrigerant is supplied to refrigerant exiting the interior heat exchanger/air handler 6, where the hot gas by-pass line 2 has a warm vapor refrigerant transport line 9 delivery point 27 that is subsequent to and beyond (based upon refrigerant flow direction as indicated by arrows 3) the interior heat exchange means 6, but prior to entry into the system's accumulator (not shown) and compressor (not shown), and where a TXV 7 has a TXV by-pass line 12 without any refrigerant 3 flow restriction, the AVs 1 cap 16 may be specially charged with another certain pressure of dry nitrogen (not shown). A dry nitrogen pressure installation line 15 is shown for use in charging the cap 16 of the AV 1 with a specific dry nitrogen (not shown) charge of approximately eighty- five psi, plus or minus approximately 5 psi, when at least one of an R-410A refrigerant and an R-407C refrigerant is utilized, so as to offset the valve spring adjustment (the spring is not shown but is well understood by those skilled in the art) when the AV 1 , if adjustable, is equal or equivalent to the valve identified below, with the adjustable screw/nut 17 at the base of the below identified valve example screwed in fully clockwise. As an example, a suitable adjustable AV 1, with the adjustable screw/nut 17 at the base of the below identified valve example screwed in fully clockwise, but with approximately one hundred ten psi of dry nitrogen in its pressure sensitive cap 16, would be a Sporlan Valve HGBE-5-95/115, as manufactured by the Sporlan Division of the Parker Hannifin Corporation, of 206 Lange Drive, Washington, MO 63090. Other valves may be utilized that have the same operational equivalencies. In this particular system design, the by-pass line 12 would not utilize a pin restrictor 13, but, instead, a solenoid valve 28, or the like, would be installed so as to permit full refrigerant 3 flow through the by-pass line 12 when the AV 1 was engaged and operating, but so as to completely block and stop the refrigerant 3 flow through the by-pass line 12 when the AV 1 was not in operation (was not engaged).

[0070] The AV 1 disclosed herein may be provided with hot refrigerant gas exiting an oil separator (not shown), after exiting the compressor (not shown), and an oil separator may be provided that is at least ninety-eight percent efficient.

[0071] Although not shown herein, an electronically controlled valve, which is well understood by those skilled in the art, could be substituted in lieu of the automatic valve, or AV 1, so long as the operative pressure settings disclosed herein are programmed in and utilized.

[0072] FIG. 4 is a side view of a compressor 23, with a primary hot refrigerant gas and oil discharge line 24, which line 24 sends refrigerant and oil (not shown except by refrigerant flow directional arrows 3) into an oil separator 25. The oil separator 25 removes most of the oil (not shown) from the hot refrigerant gas (as is well understood by those skilled in the art) and then sends the mostly all hot refrigerant gas (as shown via refrigerant flow directional arrows 3), via the oil separator's 25 mostly all hot refrigerant gas transport line 26 , into the rest of the system. The rest of the system is not shown herein as same would be well understood by those skilled in the art.

[0073] A hot gas by-pass refrigerant transport line 2 is operably connected/attached to the mostly all hot gas refrigerant transport line 26 exiting the oil separator 25. The hot gas bypass refrigerant transport line 2 is designed to deliver hot refrigerant gas to an automatic hot gas by-pass valve 1, as more fully described and explained in FIG. 1, and in FIG. 3, hereinabove.

[0074] If an oil separator 25 is not provided in the system (although a system without an oil separator 25 is not shown herein), the hot gas by-pass line 2 may be operably connected to the primary hot refrigerant gas and oil discharge line 24 from the system's compressor 23. Such an arrangement is permissible for use in conjunction with the subject disclosures.