Patent Application
20130074531
With the increasing demands on peak demand power consumption, Thermal Energy Storage (TES) has been utilized to shift air conditioning power loads to off-peak times and rates. A need exists not only for load shifting from peak to off-peak periods, but also for increases in air conditioning unit capacity and efficiency. Current air conditioning units having energy storage systems have had limited success due to several deficiencies, including reliance on water chillers that are practical only in large commercial buildings and have difficulty achieving high-efficiency.
In order to commercialize advantages of thermal energy storage in large and small commercial buildings, thermal energy storage systems must have minimal manufacturing costs, maintain maximum efficiency under varying operating conditions, have minimal implementation and operation impact and be suitable for multiple refrigeration or air conditioning applications.
Systems for providing stored thermal energy have been previously contemplated in U.S. Pat. No. 4,735,064, U.S. Pat. No. 5,225,526, both issued to Harry Fischer, U.S. Pat. No. 5,647,225 issued to Fischer et al., U.S. Pat. No. 7,162,878 issued to Narayanamurthy et al., U.S. Pat. No. 7,854,129 issued to Narayanamurthy, U.S. Pat. No. 7,503,185 issued to Narayanamurthy et al., U.S. Pat. No. 7,827,807 issued to Narayanamurthy et al., U.S. Pat. No. 7,363,772 issued to Narayanamurthy, U.S. Pat. No. 7,793,515 issued to Narayanamurthy, U.S. patent application Ser. No. 11/837,356 filed Aug. 10, 2007 by Narayanamurthy et al., application Ser. No. 12/324,369 filed Nov. 26, 2008 by Narayanamurthy et al., U.S. patent application Ser. No. 12/371,229 filed Feb. 13, 2009 by Narayanamurthy et al., U.S. patent application Ser. No. 12/473,499 filed May 28, 2009 by Narayanamurthy et al., and U.S. patent application Ser. No. 12/335,871 filed Dec. 16, 2008 by Parsonnet et al. All of these patents and applications utilize ice storage to shift air conditioning loads from peak to off-peak electric rates to provide economic justification and are hereby incorporated by reference herein for all they teach and disclose.
An embodiment of the present invention may therefore comprise: an integrated refrigerant-based thermal energy storage and cooling system comprising: a refrigerant loop containing a refrigerant comprising: a condensing unit, the condensing unit comprising a compressor and a condenser; a thermal energy storage module containing a thermal storage media and a primary heat exchanger that facilitates heat transfer from the refrigerant to the thermal storage media in a charge mode, and the primary heat exchanger that facilitates heat transfer from the thermal storage media to cool the refrigerant in a discharge mode; a storage expansion device connected downstream of the condensing unit and upstream of the thermal energy storage module; an evaporator expansion device connected downstream of the condensing unit and the thermal energy storage module; an evaporator connected downstream of the evaporator expansion device; and, a valve system that facilitates flow of refrigerant to the storage module from the compressor or the condenser or the storage expansion device or the evaporator, the valve system that facilitates flow of refrigerant from the storage module to the compressor or the condenser or the evaporator expansion device.
An embodiment of the present invention may also comprise: a method of providing cooling with a thermal energy storage and cooling system comprising: during a first time period: compressing and condensing a refrigerant with a compressor and a condenser to create a high-pressure refrigerant; expanding the high-pressure refrigerant to produce expanded refrigerant and provide storage cooling with a thermal energy storage media via a primary heat exchanger, the primary heat exchanger that is constrained within a thermal energy storage module and in thermal communication with the storage media; and, returning the expanded refrigerant to the compressor; during a second time period: compressing and condensing the refrigerant with the compressor and the condenser to create the high-pressure refrigerant; expanding a first portion of the high-pressure refrigerant to produce the first expanded refrigerant and to provide storage cooling with the thermal energy storage media via the primary heat exchanger, the primary heat exchanger that is constrained within the thermal energy storage module and in thermal communication with the storage media; expanding a second portion of the high-pressure refrigerant to provide cooling to an evaporator to produce the second expanded refrigerant; and, returning the first expanded refrigerant and the second expanded refrigerant to the compressor; during a third time period: compressing the refrigerant with the compressor to create hot, high-pressure gas refrigerant; cooling and condensing a first portion of the hot, high-pressure gas refrigerant with the storage cooling to produce warm liquid refrigerant; condensing a second portion of the high-pressure refrigerant with the condenser; mixing the first portion and the second portion and expanding mixture to provide cooling in an evaporator to produce the expanded refrigerant; and, returning the expanded refrigerant to the compressor; during a fourth time period: compressing the refrigerant with the compressor to create the hot, high-pressure gas refrigerant; cooling and condensing the hot, high-pressure gas refrigerant with the storage cooling to produce the warm liquid refrigerant; condensing the warm liquid refrigerant with the condenser to create subcooled refrigerant; expanding the subcooled refrigerant to provide cooling in an evaporator to produce the expanded refrigerant; and, returning the expanded refrigerant to the compressor; during a fifth time period: compressing and condensing the refrigerant with the compressor and the condenser to create the high-pressure refrigerant; subcooling the high-pressure refrigerant with the storage cooling to produce subcooled liquid refrigerant; expanding the subcooled liquid refrigerant to provide cooling in the evaporator to produce the expanded refrigerant; and, returning the expanded refrigerant to the compressor; during a sixth time period: compressing and condensing the refrigerant with the compressor and the condenser to create the high-pressure refrigerant; expanding the high-pressure refrigerant to provide cooling in the evaporator and produce expanded refrigerant; desuperheating the expanded refrigerant with the storage cooling to produce desuperheated refrigerant; and, returning the desuperheated refrigerant to the compressor; compressing and condensing the refrigerant with the compressor and the condenser to create the high-pressure refrigerant; expanding the high-pressure refrigerant to provide cooling in the evaporator and produce expanded refrigerant; superheating the expanded refrigerant with the storage media to produce the superheated refrigerant; and, returning superheated refrigerant to the compressor; during an eighth time period; compressing and condensing the refrigerant with the compressor and the condenser to create the high-pressure refrigerant; expanding the high-pressure refrigerant to provide cooling in the evaporator and produce expanded refrigerant; returning the expanded refrigerant to the compressor.
In the drawings,
While this invention is susceptible to embodiment in many different forms, it is shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments described.
As illustrated in
The charging modes utilize a compressor 110 to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 to a condenser 112 which removes much of the heat in the gas and discharges the heat to the atmosphere. The refrigerant leaves the condenser 112 as a warm, high-pressure liquid refrigerant delivered through a high-pressure liquid supply line where a portion of the warm liquid refrigerant is diverted by valve V3126 to valve V4128, which directs the diverted refrigerant through the storage expansion device 118. The storage expansion device 118 reduces the pressure of the warm liquid refrigerant to generate a cold mixed-phase refrigerant, which is directed to the heat exchanger 170 within the storage module 116.
This storage expansion device 118 may be a conventional or non-conventional thermal expansion valve, a static orifice, a capillary tube, a mixed-phase regulator and surge vessel (reservoir), or the like. In this mode, the heat exchanger 170 in the storage module 116 acts as an evaporator where the cold mixed-phase refrigerant absorbs heat from the storage media 160 that surrounds the heat exchanger 170 and vaporizes. The liquid refrigerant transfers cooling to thermal energy storage media 160 within the thermal energy storage module 116 (as shown, but not limited by way of example via a primary heat exchanger 170 within an insulated tank). Low-pressure vapor phase refrigerant is then returned to the compressor 110 via valve V7134 where it is mixed with the portion of the cold vapor refrigerant returning to compressor 110 via valve V6132 from the evaporator 114 that was split at valve V3126 and passed through valve V5130 and an evaporator expansion device 120. As with the storage expansion device 118, evaporator expansion device 120 may be a conventional or non-conventional thermal expansion valve, a static orifice, a capillary tube, a mixed-phase regulator and surge vessel (reservoir), or the like.
In order to meter the amount of refrigerant that is split by valve V3126, a specialized valve and controller that modulates based on downstream pressures, for example, may be used to split the amount of refrigerant that is diverted to provide immediate cooling through evaporator 114 and the amount diverted to TES for providing cooling capacity, which may be utilized at a later time. Alternatively, the storage media 160 used in the storage module 116 can be selected in order to match the refrigerant evaporating temperature of the storage module 116 to that of the evaporator 114, effectively matching the pressure drop across the storage expansion device 118 and evaporator expansion device 120 resulting in a self-metering trickle charge configuration.
The thermal energy storage unit 116 shown in
When operating in full-capacity charge mode, the compressor 110 is energized to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 and to a condenser 112, which removes much of the heat in the gas and discharges the heat to the atmosphere. The refrigerant leaves the condenser 112 as a warm, high-pressure liquid refrigerant delivered through a high-pressure liquid supply line where the entirety of the warm liquid refrigerant is diverted by valve V3126 to valve V4128, which directs the diverted refrigerant through the storage expansion device 118. Here, as in the previously described trickle charge mode, the storage expansion device 118 reduces the pressure of the warm liquid refrigerant to generate a cold mixed-phase refrigerant. In this mode, the heat exchanger 170 within the storage module 116 also acts as an evaporator where the cold mixed-phase refrigerant absorbs heat from the storage media 160 and vaporizes and transfers cooling to thermal energy storage media 160 within the thermal energy storage module 116. Low-pressure vapor phase refrigerant is then returned to the compressor 110 via valve V7134. Thus, the entirety of the cooling provided by the compressor 110 and condenser 112 (typical conventional air conditioning or refrigeration unit) is transmitted, in one contemplated embodiment, from the heat exchanger 170 to the surrounding storage media (e.g., liquid phase material that is confined within an insulated tank and may produce a block of solid phase material (ice) surrounding the freezing coils and storing thermal energy in the process).
In parallel condenser discharge mode, all basic air conditioning/refrigerant AC/R components are active including the compressor 110, condenser 112, evaporator expansion device 120, and the evaporator 114. In this mode, the compressor 110 is energized to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 where a portion of the hot, high-pressure gas is diverted by valve V1122 to the storage module 116 and heat exchanger 170, which acts as a condenser where the hot vapor rejects heat to the storage media 160, reduces temperature, and condenses. This warm liquid refrigerant is then sent to the evaporator expansion device 120 via valve V5130 where it is mixed with warm liquid refrigerant exiting the condenser 112 via valve V3126. The mixed warm liquid refrigerant is then expanded with the evaporator expansion device 120 and evaporator 114 to provide load cooling/refrigeration and returns to compressor 110 through valves V6132 and V7134 to complete the refrigeration loop.
Utilizing the heat exchanger 170 within the storage module 116 in this mode as a condenser, allows a greater amount of subcooling prior to the expansion process. This is accomplished by rejecting heat to the cold storage media 160 within the storage module 116, and improving the effectiveness of the condenser 112 by reducing the mass flow of refrigerant through condenser 112. Ultimately, the increased subcooling results in an efficiency improvement for the system by increasing the refrigeration effect of the evaporator 114. This increase in efficiency may allow an increased output by the evaporator 114 thereby effectively increasing the capacity of the AC/R system during high demand periods. This may allow a smaller system to be introduced into a new installation or to increase the capacity of an existing retrofit system application.
In the hot vapor desuperheater discharge mode, all basic AC/R components are active including the compressor 110, condenser 112, evaporator expansion device 120, and the evaporator 114. In this mode, the compressor 110 is energized to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 and is directed to the previously charged storage module 116 acting as a hot vapor desuperheater where the hot vapor refrigerant rejects heat to the storage media 160 via the heat exchanger 170 and reduces temperature. The vapor is then directed to the condenser 112 via valve V2124 where additional atmospheric heat rejection and condensation occur. The refrigerant leaves the condenser 112 where the entirety of the subcooled refrigerant is diverted by valve V3126 to valve V5130 where refrigerant is then directed to the evaporator expansion device 120. The warm liquid refrigerant is expanded and then evaporated in evaporator 114 before being returned to compressor 110 through valves V6132 and V7134.
In this mode, using the storage module 116, acting as a hot vapor desuperheater, allows a greater amount of subcooling prior to the expansion process. This is accomplished by rejecting heat to the cold storage media 160 within the storage module 116, and improving the condenser 112 effectiveness by reducing the amount of heat rejection that must occur in the condenser 112 to desuperheat the hot vapor refrigerant. Instead, more of the condenser 112 heat rejection process is used to subcool the warm liquid refrigerant. Ultimately, the increased subcooling results in an efficiency improvement for the system by increasing the refrigeration effect of the evaporator 114. This increase in efficiency may also allow an increased output by the evaporator 114, thereby effectively increasing the capacity of the AC/R system during high demand periods. This may allow a smaller system to be introduced into a new installation or to increase the capacity of an existing retrofit system application.
In the warm liquid subcooler discharge mode, all basic AC/R components are active including the compressor 110, condenser 112, evaporator expansion device 120 and the evaporator 114. In this mode, the compressor 110 is energized to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 to a condenser 112, which removes much of the heat in the gas and discharges the heat to the atmosphere. The refrigerant leaves the condenser 112 as a warm, high-pressure liquid refrigerant delivered through a high-pressure liquid supply line where the entirety of the warm liquid refrigerant is diverted by valve V3126 to valve V4128, which directs the refrigerant directly to the heat exchanger within the storage module 116, acting as a warm liquid subcooler, where the warm liquid refrigerant rejects heat and reduces temperature by transferring heat to the previously cooled thermal storage media 160.
The cooled liquid refrigerant is then directed to the evaporator expansion device 120 via valve V5130. The subcooled refrigerant is expanded and then evaporated in evaporator 114 before being returned to compressor 110 through valves V6132 and V7134. In this mode, using the storage module 116 as a warm liquid subcooler allows a greater amount of subcooling prior to the expansion process by rejecting heat to the cold storage media 160 within the storage module 116. Ultimately, the increased subcooling results in an efficiency improvement for the system by increasing the refrigeration effect of the evaporator 114. This increase in efficiency may allow an increased output by the evaporator 114, thereby effectively increasing the capacity of the AC/R system during high demand periods. This may allow a smaller system to be introduced into a new installation or to increase the capacity of an existing retrofit system application.
In cold vapor desuperheater discharge mode, all basic AC/R components are active including the compressor 110, condenser 112, evaporator expansion device 120, and the evaporator 114. In this mode, the compressor 110 is energized to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 to a condenser 112, which removes much of the heat in the gas and discharges the heat to the atmosphere. The refrigerant leaves the condenser 112 as a warm, high-pressure liquid refrigerant delivered through a high-pressure liquid supply line where the warm liquid refrigerant is diverted by valve V3126 to valve V5130 where refrigerant is then directed to the evaporator expansion device 120. The refrigerant is expanded and then evaporated in evaporator 114 in a conventional manner and the expanded refrigerant is then diverted by valve V6132 to the pre-charged storage module 116 acting as a cold vapor desuperheater where the cold vapor refrigerant rejects heat to the storage media 160 and reduces temperature before being returned to compressor 110 through valve V7134.
In this mode, using the storage module 116 as a cold vapor desuperheater, allows a greater amount of subcooling prior to the expansion process by rejecting heat to the cold storage media 160 within the storage module 116, and improving the condenser 112 effectiveness by reducing the amount of heat rejection that must occur in the condenser 112 to desuperheat the hot vapor refrigerant. Instead, more of the condenser 112 heat rejection process is used to subcool the warm liquid refrigerant. Ultimately, the increased subcooling results in an efficiency improvement for the system by increasing the refrigeration effect of the evaporator 114. This increase in efficiency may allow an increased output by the evaporator 114 thereby effectively increasing the capacity of the AC/R system during high demand periods. This may allow a smaller system to be introduced into a new installation or to increase the capacity of an existing retrofit system application.
In suction line charge mode, all basic AC/R components are active including the compressor 110, condenser 112, evaporator expansion device 120, and the evaporator 114. In this mode, the compressor 110 is energized to compress cold, low pressure refrigerant gas to hot, high-pressure gas. This refrigerant passes through valve V1122 to a condenser 112, which removes much of the heat in the gas and discharges the heat to the atmosphere. The refrigerant leaves the condenser 112 as a warm, high-pressure liquid refrigerant delivered through a high-pressure liquid supply line where the warm liquid refrigerant is diverted by valve V3126 to valve V5130 where refrigerant is then directed to the evaporator expansion device 120. The refrigerant is expanded and then evaporated in evaporator 114 in a conventional manner and the expanded refrigerant is then diverted by valve V6132 to the uncharged storage module 116 acting as a cold vapor superheater where residual cooling that remains in the effluent cold vapor refrigerant leaving the evaporator 114, is transferred to the storage media 160, and the temperature of the cold vapor refrigerant increases. The superheated vapor refrigerant exits the storage module 116 and returns to compressor 110 through valve V7134.
In this mode, using the storage module 116 as a cold vapor superheater, allows an amount of charging (cooling) of the thermal storage media 160 prior to compressing the superheated refrigerant. This places more strain on the compressor 110, but allows an additional mode of charging the storage module while providing conventional cooling with the evaporator 114.
An additional loop may be utilized in the embodiment described in
As illustrated in
). Thus, each of the charge mode 180 valve configurations is shown, and in a similar manner the four discharge modes 190 and a bypass mode 199 are schematically illustrated.
The liquid refrigerant transfers cooling to thermal energy storage media 160 within the thermal energy storage module 116 (shown here as a primary heat exchanger 170 within an insulated tank). Low-pressure vapor phase refrigerant is then returned to the compressor 110 where it is mixed with the portion of the cold vapor refrigerant returning to compressor 110 from the evaporator 114 that was split at the valve and passed through an evaporator expansion device 120. As with the storage expansion device 118, evaporator expansion device 120 may be a conventional or non-conventional thermal expansion valve, a static orifice, a capillary tube, a mixed-phase regulator and surge vessel (reservoir), or the like.
As was described in
The thermal energy storage unit 116 shown in FIGS. 1 and 3-9 may typically comprise an insulated tank that houses the primary heat exchanger 170 surrounded by, for example, solid, liquid coolant, eutectic or liquid phase material and/or solid phase material or the like, (fluid/ice) depending on the current system mode). The primary heat exchanger 170 may typically further comprise a lower header assembly connected to an upper header assembly with a series of freezing and discharge coils to make a fluid/vapor loop within the insulated tank. Such systems are disclosed in the patents and applications referred to above, which are incorporated by reference.
The disclosed system may utilize a relatively small capacity condenser compressor (air conditioner) and have the ability to deliver high capacity cooling utilizing thermal energy storage. This variability may be further extended by specific sizing of the compressor and condenser components within the system. Whereas the aforementioned refrigerant loops have been described as having a particular direction, it is shown and contemplated that these loops may be run in either direction whenever possible.
The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.
This application is based upon and claims the benefit of U.S. provisional application No. 61/470,841, entitled “Refrigerant Circuit with Integrated Multi-Mode Thermal Energy Storage,” filed Apr. 1, 2011 and the entire disclosures of which is hereby specifically incorporated by reference for all that it discloses and teaches.
| Number | Date | Country | |
|---|---|---|---|
| 61470841 | Apr 2011 | US |
