The present invention relates to a refrigeration system. The present invention relates more particularly to a refrigeration system with a multi-function heat exchanger that includes a condenser, evaporator and subcooler as a single unit, and that interfaces with an external refrigerant expansion device.
It is well known to provide heat exchangers for use in refrigeration system. However, such known heat exchangers typically do not serve the combined purpose of a condenser for condensing refrigerant gas discharged from a compressor, along with an evaporator or chiller for chilling a secondary coolant loop that provides cooling to refrigerated display cases, into a single device. In several instances where a condenser has been combined with an evaporator, the combined units typically include an internal refrigerant expansion device and resulted in a number of disadvantages for use in applications with refrigerated display cases. Accordingly, it would be desirable to provide a refrigeration system with a multi-function heat exchanger that combines in a single device the functions of a condenser that receives a cool liquid for condensing hot refrigerant gas discharged from a compressor, and a chiller that receives cold, expanded refrigerant to chill a secondary loop of coolant (e.g. glycol, etc.) that is distributed to loads such as refrigerated display cases to cool products therein, in a manner that overcomes the disadvantages of prior heat exchangers.
The present invention relates to a refrigeration system with a multi-function heat exchanger for providing cooling to one or more loads within a facility. The system includes a heat exchanger shell having an internal partition separating the shell into a top portion defining a condenser, and a bottom portion defining a subcooler and an evaporator. A discharge gas inlet, a condensate outlet, a condensing fluid inlet and a condensing fluid outlet are disposed on the top portion. A liquid subcooler inlet, a subcooled liquid outlet, an evaporator gas inlet, a suction evaporator outlet, a secondary coolant inlet, and a secondary coolant outlet are disposed on the bottom portion. An expansion device is disposed external of the shell and in fluid communication with the subcooled liquid outlet and the evaporator gas inlet. A primary refrigeration loop has a compressor and circulates a refrigerant from the compressor through a refrigerant flow path including the discharge gas inlet, the condenser, the condensate outlet, the liquid subcooler inlet, the subcooler, the subcooled liquid outlet, the expansion device, the evaporator gas inlet, the evaporator, the suction evaporator outlet, and back to the compressor. A secondary coolant loop circulates a liquid coolant from the loads through a secondary cooling flow path including the secondary coolant inlet, the secondary coolant outlet, and back to the loads. A control system includes a control module that receives a first signal representative of refrigerant temperature proximate the suction evaporator outlet and a second signal representative of refrigerant pressure proximate the suction evaporator outlet, and provides a control signal to the expansion device to maintain a desired superheat temperature of the refrigerant proximate the suction evaporator outlet. A condenser cooling loop has an outdoor heat exchanger and circulates a condensing fluid from the outdoor heat exchanger through a condensing flow path including the condensing fluid inlet, the condenser, the condensing fluid outlet, and back to the outdoor heat exchanger.
Referring to the FIGURES, a refrigeration system with a multi-function heat exchanger is illustrated schematically according to an exemplary embodiment where a condenser, evaporator (or chiller) and subcooler are combined in a single unit so that one portion (shown for example as a top portion) serves as a condenser and another portion (shown as a bottom portion) serves as the subcooler and chiller. The top condenser receives a liquid (e.g. water) cooled from an air-cooled device and returns the liquid to the air-cooled device. The liquid condenses the hot refrigerant gas discharged from the compressor. The condensed refrigerant leaves the condenser and is directed into the bottom portion to be subcooled and is then directed to an external expansion device. The subcooled liquid refrigerant is expanded in the expansion device (e.g. throttle valve, etc.) and then directed back into the bottom portion where it chills a secondary loop of coolant that is then circulated to loads (e.g. refrigerated display cases, etc.) throughout a facility.
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According to the illustrated embodiment, the expansion device 50 is disposed external of the heat exchanger 20 and is controlled by a signal representative of a superheat temperature of the refrigerant at (or proximate to) the suction evaporator outlet 42 of the heat exchanger 20. For a medium-temperature refrigeration system, the saturation temperature of the refrigerant leaving the expansion device is typically within a range of approximately 17-32 degrees F., and more particularly within a range of 22-29 degrees F. and is intended to chill the loop 70 of secondary coolant in the evaporator portion 30. According to another exemplary embodiment for a low-temperature refrigeration system, the saturation temperature of the refrigerant is typically within a range of approximately minus (−)22 to minus (−)5 degrees F. However, the temperature ranges are described by way of example and any temperature range suitable for use in a refrigeration system for a desired application may be used. As the saturated liquid-vapor mixture of refrigerant progresses through the evaporator portion 30 and absorbs heat from the loop 70 of secondary coolant, the vapor percentage of the liquid-vapor mixture increases, and usually becomes completely vaporized. When the refrigerant is completely vaporized near the suction evaporator outlet 42 of the heat exchanger 20, the refrigerant temperature increases above the refrigerant's saturation temperature. The amount of temperature increase above the saturation temperature is referred to herein as the “superheat temperature.” The expansion device 50 is configured to modulate a flow rate of the refrigerant corresponding to the duty or demand experienced by loop 70 of secondary coolant as it returns from the loads throughout the facility.
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According to any exemplary embodiment, a refrigeration system includes a multi-function shell and tube heat exchanger where a condenser, evaporator (e.g. chiller) and subcooler are combined in a single unit. The top condenser portion receives a liquid cooled from an air-cooled device and returns the liquid to the air-cooled device. The liquid condenses the hot refrigerant gas discharged from the compressor. The condensed refrigerant leaves the condenser and is directed into the bottom portion to be subcooled. The subcooled liquid refrigerant is expanded in an externally disposed expansion device and then directed back into the bottom portion where it chills a secondary loop of coolant that is circulated to loads throughout a store or other facility.
It is important to note that the construction and arrangement of the elements and embodiments of the refrigeration system with multi-function shell and tube heat exchanger provided herein are illustrative only. Although only a few exemplary embodiments of the present invention have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible in these embodiments (such as variations in features such as components, valves, and fittings, structures, shapes, dimensions and proportions of the components of the system, use of materials, etc.) without materially departing from the novel teachings and advantages of the invention. According to other alternative embodiments, the refrigeration system with multi-function shell and tube heat exchanger may be used with any loads for transferring heat from one space to be cooled to another space or source designed to receive the rejected heat and may include commercial, institutional or residential refrigeration systems. Further, it is readily apparent that variations of the refrigeration system with multi-function shell and tube heat exchanger and its components and elements may be provided in a wide variety of types, shapes, sizes and performance characteristics, or provided in locations external or partially external to the refrigeration system. For example, components of the refrigeration system with multi-function shell and tube heat exchanger may be provided as rack-mounted system, or as a custom-installed hard-piped system, or may be provided as a modular unit or package. Accordingly, all such modifications are intended to be within the scope of the invention.
The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the inventions as expressed in the appended claims.
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Number | Date | Country | |
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20110185757 A1 | Aug 2011 | US |