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US 12,203,693 B2Granted
Hot gas defrost using fluid from high pressure tank
AssigneeHeatcraft Refrigeration Products LLC
InventorShitong Zha
Life of this patent
Estimating the term…
Abstract
A refrigeration system includes pressure-regulating valve positioned between two flash tanks and a heat exchanger is positioned downstream from a medium temperature compressor. After determining that operation of an evaporator in a defrost mode is indicated, the system causes the evaporator to operate in the defrost mode by adjusting the pressure-regulating valve to increase a pressure of a first flash tank relative to a pressure of a second flash tank, allowing flow of refrigerant from the first flash tank to the heat exchanger, and allowing refrigerant heated by the heat exchanger to flow to the first evaporator.
Claims17
A refrigeration system, comprising:
- a plurality of evaporators, each configured to transfer heat from a space to refrigerant, wherein each of the plurality of evaporators has a sensor associated with it for measuring at least one of a temperature or a pressure;
- one or more medium temperature compressors configured to output compressed refrigerant;
- a first flash tank configured to receive and store cooled refrigerant provided by a gas cooler;
- a second flash tank configured to receive and store a portion of the cooled refrigerant from the first flash tank;
- an adjustable pressure-regulating valve disposed in refrigerant conduit coupling the first flash tank to the second flash tank, wherein when each of the plurality of evaporators is operated in a refrigeration mode the adjustable pressure-regulating valve is fully open and the first flash tank and second flash tank are held at a same flash tank pressure, wherein when at least one of the plurality of evaporators is operated in a defrost mode the adjustable pressure-regulating valve is at least partially closed and configured to selectively increase a first flash tank pressure in the first flash tank relative to a second flash tank pressure in the second flash tank;
- a heat exchanger positioned between an outlet of the one or more medium temperature compressors and an inlet of the gas cooler, the heat exchanger configured to receive the compressed refrigerant from the one or more medium temperature compressors and provide the compressed refrigerant to the gas cooler, and when at least one evaporator of the plurality of evaporators is operated in the defrost mode, to transfer heat from the compressed refrigerant output by the one or more medium temperature compressors to a flow of refrigerant from the first flash tank;
- and a controller communicatively coupled to the pressure-regulating valve, wherein the controller is configured to:
- determine that operation of a first evaporator of the plurality of evaporators in the defrost mode is indicated by the sensor associated with it, wherein the defrost mode is indicated when the measurement associated with the first evaporator is less than a threshold value;
- and
- after determining that operation of the first evaporator in the defrost mode is indicated, cause the first evaporator to operate in the defrost mode by:
- adjusting the pressure-regulating valve to increase the first flash tank pressure of the first flash tank relative to the second flash tank pressure of the second flash tank, wherein the controller is further configured to cause the first evaporator to operate in the defrost mode by partially closing the pressure-regulating valve;
- allowing flow of refrigerant from the first flash tank to the heat exchanger based on the increased first flash tank pressure;
- and
- allowing refrigerant heated by the heat exchanger to flow to the first evaporator.
11 more elements
A method of operating a refrigeration system, the method comprising:
- operating a first evaporator of a plurality of evaporators in a refrigeration mode, wherein each of the plurality of evaporators has a sensor associated with it for measuring at least one of a temperature or a pressure;
- determining that operation of the first evaporator in a defrost mode is indicated;
- and
- after determining that operation of the first evaporator in the defrost mode is indicated, causing the first evaporator to operate in the defrost mode by:
- adjusting an adjustable pressure-regulating valve disposed in refrigerant conduit coupling a first flash tank to a second flash tank, the adjustable pressure-regulating valve configured to selectively increase a first flash tank pressure of the first flash tank relative to a second flash tank pressure of the second flash tank, wherein the first flash tank is configured to receive and store refrigerant cooled by a gas cooler and the second flash tank is configured to receive and store a portion of the cooled refrigerant from the first flash tank;
- causing the first evaporator to operate in the defrost mode by partially closing the pressure-regulating valve;
- allowing a flow of refrigerant from the first flash tank to a heat exchanger based on the increased first flash tank pressure, the heat exchanger positioned between an outlet of one or more compressors of the refrigeration system and an inlet of the gas cooler, wherein the heat exchanger is configured to receive the refrigerant from the one or more compressors and provide the refrigerant to a gas cooler and when the defrost mode is indicated, to transfer heat from the refrigerant received from the one or more compressors to the flow of refrigerant from the first flash tank to the heat exchanger;
- and
- allowing refrigerant heated by the heat exchanger to flow to the first evaporator,
- wherein the defrost mode is indicated by the sensor associated with the first evaporator when the measurement associated with the first evaporator is less than a threshold value.
7 more elements
A controller of a refrigeration system, the controller comprising:
- an input/output interface communicatively coupled to an adjustable pressure-regulating valve disposed in refrigerant conduit coupling a first flash tank to a second flash tank and configured to selectively increase a first flash tank pressure of the first flash tank relative to a second flash tank pressure of the second flash tank, wherein the first flash tank is configured to receive and store refrigerant cooled by a gas cooler and the second flash tank is configured to receive and store a portion of the cooled refrigerant from the first flash tank;
- and
- a processor configured to:
- determine that operation of a first evaporator of a plurality of evaporators in a defrost mode is indicated, wherein each of the plurality of evaporators has a sensor associated with it for measuring at least one of a temperature or a pressure and wherein the defrost mode is indicated by the sensor associated with the first evaporator when the measurement associated with the first evaporator is less than a threshold value;
- and
- after determining that operation of the first evaporator in the defrost mode is indicated, cause the first evaporator to operate in the defrost mode by:
- adjusting the pressure-regulating valve to increase the first flash tank pressure of the first flash tank relative to the second flash tank pressure of the second flash tank;
- allowing a flow of refrigerant from the first flash tank to a heat exchanger based on the increased first flash tank pressure, wherein the heat exchanger is positioned between an outlet of one or more medium temperature compressors and an inlet of the gas cooler, the heat exchanger configured to receive compressed refrigerant from the one or more medium temperature compressors and the heat exchanger provides the compressed refrigerant to the gas cooler;
- and
- allowing refrigerant from the first flash tank to be heated by the heat exchanger to flow to the first evaporator,
- wherein the processor is further configured to cause the first evaporator to operate in the defrost mode by partially closing the pressure-regulating valve.
8 more elements
Dependencies are inferred from the claim text.