Patent Application
20240200841
This invention relates to the field of refrigeration circuits, and more particularly, an improved, reliable, and power-efficient refrigeration circuit.
Existing refrigeration circuits generally have refrigeration installations operating in dry expansion with superheat, where superheat section in the evaporators may have significantly lower heat transfer efficiency. In addition, compressors of existing refrigeration circuits may be needed to be operated in direct expansion mode to protect the compressor from liquid refrigerant which may harm the bearings of the compressors. Moreover, carbon dioxide (CO2)-based refrigeration systems may operate less efficiently in summer or hot ambient conditions due to the thermodynamics of CO2. As a result, high exit temperature at the outlet of the gas-cooler in the refrigeration circuit may result in more flash vapor, thereby requiring more compressors to run the refrigeration circuit.
Described herein is a refrigeration circuit comprising a gas-cooler comprising an inlet and an outlet, and a compressor unit comprising one or more compressor, wherein an outlet of the compressor unit is fluidically connected to the inlet of the gas-cooler. The refrigeration circuit further comprises one or more evaporators, each comprising an inlet, and an outlet, wherein the outlet of the one or more evaporators is fluidically coupled to the inlet of the compressor unit. The refrigeration circuit further comprises a flash tank fluidically connected between one or more of the gas-cooler and the compressor unit, and the one or more evaporators and the compressor unit. Further, the refrigeration circuit comprises one or more thermal battery fluidically coupled to the gas-cooler, the flash tank, the compressor unit, and the one or more evaporators.
In one or more embodiments, the circuit comprises a controller operatively coupled to one or more components of the refrigeration circuit, wherein the controller is configured to monitor one or more parameters associated with the refrigeration circuit, and control operation of the one or more components of the refrigeration circuit.
In one or more embodiments, the controller is in communication with a database associated with one or more electric power service provider, wherein the controller is configured to: receive, from the database, data pertaining to electricity grid information associated with an electrical grid connected to the refrigerant circuit, and control, based on the electricity grid information, the flow of a refrigerant associated with the refrigeration circuit between one or more of the gas-cooler and the thermal battery, the thermal battery and the one or more evaporator, and/or the thermal battery and the compressor unit.
In one or more embodiments, when the electricity pricing is below a predefined level, the controller enables the flash tank via a dedicated valve to supply and evaporate the refrigerant in the thermal battery to cool a buffer associated with the thermal battery at a first temperature and act as a heat source.
In one or more embodiments, when temperature at the outlet of the gas-cooler exceeds a predefined temperature and/or when the electricity pricing is above the predefined level, the buffer of the thermal battery acting as the heat sink is melted to cool the refrigerant flowing therethrough, wherein the cooled refrigerant is supplied to the outlet of the gas-cooler to reduce the temperature at the outlet of the gas-cooler below the predefined temperature.
In one or more embodiments, when the electricity pricing is above the predefined level, the controller enables melting of the buffer acting as the heat sink to cool the refrigerant flowing therethrough to a second temperature and further supply the cooled refrigerant to the one or more evaporators.
In one or more embodiments, the controller is configured to enable the flow of the refrigerant being heated in the refrigeration circuit, through the thermal battery to store thermal energy of the heated refrigerant in the buffer such that the thermal battery acts as a heat source.
In one or more embodiments, the controller is configured to enable the thermal battery acting as the heat source to heat the refrigerant flowing therethrough to a super-heated temperature; and supply the super-heated refrigerant from the thermal battery to the compressor unit.
Also described herein is a refrigeration circuit comprising a gas-cooler comprising an inlet, and an outlet, and a compressor unit comprising one or more compressor, wherein the outlet of the compressor unit is fluidically coupled to the inlet of the gas-cooler. The refrigeration circuit further comprises a thermal battery comprising a first inlet, a first outlet, a second inlet, and second outlet, wherein the gas-cooler is fluidically coupled to the thermal battery. Further, the refrigeration circuit comprises a flash tank comprising an inlet, a vapor outlet, and a liquid outlet, wherein the vapor outlet of the flash tank is fluidically coupled to an inlet of the compressor unit via a heat exchanger. The refrigeration circuit further comprises one or more evaporators, each comprising an inlet, and an outlet, wherein, the second inlet of the thermal battery is fluidically coupled to the outlet of the one or more evaporator, the vapor outlet and the liquid outlet of the flash tank are fluidically coupled to the inlet of the one or more evaporators via the heat exchanger and a first expansion valve, the vapor outlet and the liquid outlet of the flash tank are fluidically coupled to the second inlet of the thermal battery via the heat exchanger and a second expansion valve, and the second outlet of the thermal battery is fluidically coupled to the inlet of the compressor unit.
In one or more embodiments, wherein the refrigeration circuit comprises a three-way valve comprising a first port, a second port, and a third port, wherein, the first port of the three-way valve is fluidically coupled to the outlet of the gas-cooler, the first outlet of the thermal battery is fluidically coupled to the second port of the three-way valve, the third port of the three-way valve is fluidically coupled to the inlet of the flash tank, and the outlet of the gas-cooler is fluidically coupled to the first inlet of the thermal battery.
In one or more embodiments, the refrigeration circuit comprises a controller in communication with a database associated with one or more electric power service provider, wherein the controller is configured to receive, from the database, data pertaining to electricity grid information associated with an electrical grid connected to the refrigerant circuit, and control, based on the electricity grid information, the flow of a refrigerant associated with the refrigeration circuit between one or more of the gas-cooler and the thermal battery, the thermal battery and the one or more evaporator, and/or the thermal battery and the compressor unit.
In one or more embodiments, when an electricity pricing of the electric grid is below a predefined level, the controller enables the flash tank to supply and evaporate the refrigerant in the thermal battery to cool a buffer associated with the thermal battery at a first temperature and act as a heat source.
In one or more embodiments, when temperature at the outlet of the gas-cooler exceeds a predefined temperature and/or when the electricity pricing is above the predefined level, the buffer of the thermal battery acting as the heat sink is melted to cool the refrigerant flowing therethrough, wherein the cooled refrigerant is supplied to the outlet of the gas-cooler via the three-way valve to reduce the temperature at the outlet of the gas-cooler below the predefined temperature.
In one or more embodiments, when the electricity pricing is above the predefined level, the controller enables melting of the buffer acting as the heat sink to cool the refrigerant flowing therethrough to a second temperature and further supply the cooled refrigerant to the one or more evaporators.
In one or more embodiments, the controller is configured to enable the thermal battery acting as the heat source to heat the refrigerant flowing therethrough to a super-heated temperature, and supply the super-heated refrigerant from the thermal battery to the compressor unit.
Further described herein is a refrigeration circuit comprising a gas-cooler comprising an inlet, and an outlet, and a compressor unit comprising one or more compressor, wherein the outlet of the compressor unit is fluidically coupled to the inlet of the gas-cooler. The refrigeration circuit further comprises a thermal battery comprising an inlet and an outlet, wherein the outlet of the gas-cooler is fluidically coupled to the inlet of the thermal battery via a first heat exchanger, and a second heat exchanger. The refrigeration circuit further comprises a flash tank comprising an inlet, a vapor outlet, and a liquid outlet, wherein the third port of the three-way valve is fluidically coupled to the inlet of the flash tank via the first heat exchanger, and the vapor outlet of the flash tank is fluidically coupled to an inlet of the compressor unit via a third heat exchanger. Further, the refrigeration circuit further comprises one or more evaporators, each comprising an inlet, and an outlet, wherein the inlet of the thermal battery is fluidically coupled to the outlet of the one or more evaporators via the second heat exchanger; the liquid outlet and the vapor outlet of the flash tank are fluidically coupled to the inlet of the one or more evaporator via the heat exchanger, and a first expansion valve; the liquid outlet and the vapor outlet of the flash tank are fluidically coupled to the inlet of the thermal battery via the second heat exchanger, the second heat exchanger, and a second expansion valve; and the outlet of the thermal battery is fluidically coupled to the inlet of the compressor unit.
In one or more embodiments, wherein the refrigeration circuit comprises a three-way valve comprising a first port, a second port, and a third port, wherein, the first port of the three-way valve is fluidically coupled to the inlet of the thermal battery via the second heat exchanger, the second port of the three-way valve is fluidically coupled the outlet of the thermal battery, the third port of the three-way valve is fluidically coupled to the inlet of the flash tank via the first heat exchanger, and the outlet of the thermal battery is fluidically coupled to the inlet of the compressor unit via the three-way valve and the second heat exchanger.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings.
The accompanying drawings are included to provide a further understanding of the subject disclosure of this invention and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the subject disclosure and, together with the description, serve to explain the principles of the subject disclosure.
In the drawings, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject disclosure as defined by the appended claims.
Various terms are used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the subject disclosure, the components of this invention. described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” “first”, “second” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the gas-cooler, evaporator, compressor, flash tank, thermal battery, heat exchanger, and corresponding components, described herein may be oriented in any desired direction.
This invention provides an improved, reliable, and power-efficient refrigeration circuit having thermal storage. The refrigeration circuit may comprise a gas-cooler having CO2 as refrigerant, a compressor unit comprising multiple compressors, a flash tank, and one or more evaporators associated with one or more loads such as, but not limited to, refrigeration cabinets. The refrigeration circuit may include a thermal battery having a buffer, which may include a phase-changing material. The refrigeration circuit may allow loading (cooling/freezing) of the buffer when electricity pricing is cheaper and may further allow the buffer to melt against the gas-cooler outlet to reduce the power consumption if the cost of electricity is high or if ambient conditions are on a peak period of the day. Moreover, the refrigeration circuit may allow a lift of evaporation temperature in the refrigeration circuit, which may improve the overall efficiency. The refrigeration circuit may also allow the users to easily retrofit refrigeration cabinets or to size the initial equipment smaller.
Referring to
In one or more operations, a refrigerant, such as CO2, and the like may be circulated through the refrigeration circuit 100. A low-pressure vapor line (using a conduit) may deliver the refrigerant to the compressor(s) 102 in gaseous form. The compressor(s) 102 may then increase the pressure of the refrigerant and deliver high-pressure refrigerant to the condenser or gas-cooler 104 through a high-pressure line. As shown in the pressure/enthalpy (PH) diagram of
The two-phase refrigerant leaving the outlet of the gas-cooler 104 may enter the flash tank 106 through the flash tank inlet. Additionally, a high-pressure valve 116 (HPV) may be installed between the outlet of the gas-cooler 104 and the flash tank inlet. As shown in the PH diagram of
In the evaporator 108, heat may be transferred from the environment to the liquid refrigerant. This heat may cause the refrigerant to vaporize, thereby removing heat from the environment. As shown in the PH diagram of
Referring to
The vapor outlet of the flash tank 106 may be fluidically coupled to the inlet of the compressor unit 102 via a heat exchanger 114 such as but not limited to a brazed-plate heat exchanger. Additionally, a medium pressure valve (MPV) 118 may be configured between the vapor outlet of the flash tank 106 and the heat exchanger 114. As shown in the PH diagram of
Referring to
The outlet of the thermal battery 110 may be fluidically coupled to the second port of the three-way valve 112 and the outlet of the thermal battery 110 may be further fluidically coupled to the inlet of the compressor unit 102 via the three-way valve 112 and the second heat exchanger 114-2. Further, the first port of the three-way valve 112 may be fluidically coupled to the inlet of the thermal battery 110 via the second heat exchanger 114-2 and the third port of the three-way valve 112 may be fluidically coupled to the inlet of the flash tank 106 via the first heat exchanger 114-1. Additionally, a high-pressure valve (HPV) 116 may be configured between the first heat exchanger 114-1 and the inlet of the flash tank 106.
The vapor outlet of the flash tank 106 may be fluidically coupled to the inlet of the compressor unit 102 via a third heat exchanger 114-3. Additionally, a medium pressure valve (MPV) 118 may be configured between the vapor outlet of the flash tank 106 and the third heat exchanger. As shown in the PH diagram of
Referring back to
In one or more embodiments, when the electricity pricing of the electric grid is below a predefined level (electricity is less costly), the flash tank 106 may be operated by the electrical power received from the electrical grid to supply and evaporate the refrigerant in the thermal battery 110 to cool the buffer to a first temperature so that the flash tank 106 may act as a heat sink.
Accordingly, in one or more embodiments, when the temperature at the outlet of the gas-cooler 104 exceeds a predefined temperature (such as an ambient temperature) or when the electricity pricing is above the predefined level (electricity is expensive), the buffer of the thermal battery 110 acting as the heat sink may be melted to cool the refrigerant by allowing the refrigerant to flow through the thermal battery 110. The cooled refrigerant may then exit the first outlet of the thermal battery 110 and be supplied to the outlet of the gas-cooler 104 via the three-way valve 112 to reduce the temperature at the outlet of the gas-cooler 104 below the ambient temperature. This may help reduce the flash vapor generated from the gas-cooler 104 as shown in
In some embodiments, a simple expansion valve may be used to load the buffer, however, to optimize the refrigeration circuit 100 and installations, the cabinets or cold room evaporators 108 may be operated in dry expansion mode, which usually utilizes superheated gas at 6-8 Kelvin temperature. Still, a section of the evaporator 108 may be a super-heated section with low strength, so, the installations may be operated in a semi-flooded mode, where the installations are operated with a very low superheat control signal, which ends up in having 10% of liquid at the end of the evaporator, which is usually desirable because liquid refrigerant will damage the bearings in the compressor. To overcome the above limitations, the refrigeration circuit 100 may allow the thermal battery 110 to operate as a heat source to evaporate the overheated liquid, such that at the outlet of the thermal battery 110 may provide superheated gas, which is good for the compressors 102.
In one or more embodiments, when the electricity pricing is above the predefined level, the buffer acting as the heat sink may be melted to cool the refrigerant flowing therethrough to a second temperature. The cool refrigerant may then be supplied to the one or more evaporators 108 associated with the refrigeration installations. In the evaporator 108, heat may be transferred from the cabinet storage space to the cool refrigerant coming from the thermal battery 110, which may cause the refrigerant to heat and vaporize, and cool the storage space of the cabinets. Accordingly, the refrigeration circuit 100 can ramp up and ramp down simultaneously on multiple refrigeration installations, when the electrical load is either in the positive or the negative direction.
In one or more embodiments, in the evaporator 108, heat may be transferred from the cabinet storage space to the liquid refrigerant, which may cause the refrigerant to heat and vaporize. The heated refrigerant leaving the outlet of the evaporator 108 may be delivered to the compressors 102 through the thermal battery 110 where the buffer may store the heat and act as a heat source. Later on, the liquid/vapor refrigerant leaving the outlet of the flash tank 106 may be delivered through the thermal battery 110, where the temperature of the refrigerant may be further increased to vaporize the refrigerant using the heat stored in the thermal battery 110 (acting as heat source). Accordingly, the supply of heat by the thermal battery 110 may facilitate the heating of the refrigerant to a super-heated temperature, which may be supplied to the compressor unit 102, thereby reducing the load on the compressors 102 and improving the longevity of the compressors 102.
In one or more embodiments, the buffer of the thermal battery 110 may be a phase-changing material (PCM) such as but not limited to paraffin, however, water may also be used as the PCM since evaporation is maintained around minus eight to minus five degrees Celsius in the invention. Fresh water may be used without the need for brine or paraffin as PCM.
In one or more embodiments, the refrigeration circuit 100 may include a controller 122 operatively coupled to the components of the refrigeration circuit 100. The controller 122 may be configured to monitor one or more parameters associated with the refrigeration circuit 100 using flow meters installed in conduits (lines) used for fluidically connecting the components of the refrigeration circuit 100. Further, the controller 122 may involve pressure sensors and temperature sensors to monitor the temperature and pressure of the refrigerant within the refrigeration circuit 100. The controller 122 can include a communication unit that connects the controller 122 to the components of the refrigeration circuit 100 and an electrical grid. The controller 122 may be in communication with a database of one or more electric power service providers associated with the electrical grid.
The controller 122 is configured to receive, from the database, data pertaining to electricity pricing associated with the electrical grid connected to the refrigerant circuit. The controller 122 may accordingly control the operation of the components of the refrigeration circuit 100 to control the flow of a refrigerant associated with the refrigeration circuit 100 between one or more of the gas-cooler 104 and the thermal battery 110, the thermal battery 110 and the evaporator 108, and/or the thermal battery 110 and the compressor unit 102. For instance, when the electricity pricing is below a predefined level, the controller 122 enables the flash tank 106 to supply and evaporate the refrigerant in the thermal battery 110 to cool a buffer associated with the thermal battery 110. Further, when the temperature at the outlet of the gas-cooler 104 exceeds a predefined (ambient) temperature or when the electricity pricing is above the predefined level, the controller 122 may enable the melting of the buffer of the thermal battery 110 to cool the refrigerant flowing therethrough and supply the cooled refrigerant to the outlet of the gas-cooler 104 to reduce the temperature at the outlet of the gas-cooler 104 below the ambient temperature, thereby reducing flash vapor and reducing the load on the compressors 102.
Further, when the electricity pricing is above the predefined level, the controller 122 may enable the melting of the buffer acting to cool the refrigerant flowing therethrough and further enable the supply of the cooled refrigerant to the one or more evaporators 108. Furthermore, the controller 122 may be configured to enable the flow of the refrigerant being heated in the refrigeration circuit 100, through the thermal battery 110 to store the thermal energy received from the heated refrigerant in the buffer such that the thermal battery 110 acts as a heat source. Thus, the controller 122 may enable the thermal battery 110 to act as the heat source to heat the refrigerant flowing therethrough to a super-heated temperature; and supply the super-heated refrigerant from the thermal battery 110 to the compressor unit 102.
Thus, the refrigeration circuit provides an improved, reliable, and power-efficient refrigeration circuit having a thermal storage. The refrigeration circuit allows loading (cooling/freezing) of the buffer when electricity pricing is cheaper and may further allow the buffer to melt against the gas-cooler outlet to reduce the power consumption if the cost of electricity is high or if ambient conditions are on a peak period of the day. Peak periods are defined as times at which the electricity usage is greater than average. Moreover, the refrigeration circuit may allow a lift of evaporation temperature in the refrigeration circuit, which may improve the overall efficiency. In addition, the refrigeration circuit also allows the users to easily retrofit refrigeration cabinets (loads) and size the initial equipment smaller.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined by the appended claims. Modifications may be made to adopt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention includes all embodiments falling within the scope of the invention as defined by the appended claims.
In interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
This patent application claims the benefit of U.S. Provisional Patent Application No. 63/387,665, filed on Dec. 15, 2022, which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63387665 | Dec 2022 | US |
