Patent Publication Number: US-2015075212-A1

Title: Carbon Dioxide Refrigeration System with a Multi-Way Valve

Description:
TECHNICAL FIELD 
     The present application and the resultant patent relate generally to refrigeration systems and more particularly relate to carbon dioxide refrigeration systems used with light commercial or household appliances with an expansion device having a multi-way valve to avoid pressure equalization between compressor cycles for improved energy efficiency. 
     BACKGROUND OF THE INVENTION 
     Modern refrigeration systems provide cooling, ventilation, and humidity control for all or part of an enclosure such as a cooler, a dispenser, and other types of appliances. These modern refrigeration systems are increasing moving away from the use of synthetic refrigerants for a number of reasons. Given such, there is an increased interest in the use of natural refrigerants such as carbon dioxide and the like. Carbon dioxide as a refrigerant has the advantage of being relatively inexpensive, readily available, non-toxic, nonflammable, and environmentally friendly. Moreover, carbon dioxide generally has a higher volumetric capacity than most known synthetic refrigerants. 
     Generally described, a supercritical or other type of a carbon dioxide refrigeration cycle may be similar to other types of refrigeration cycles but may operate at a higher pressure and may not involve a change in state. The typical carbon dioxide refrigeration cycle may include compressing the flow of carbon dioxide within a compressor at a high pressure and a high temperature. Second, the compressed carbon dioxide may be cooled within a gas cooler or other type of heat exchanger by heat exchange with the surrounding environment. Third, the carbon dioxide passes through an expansion device that reduces both the pressure and the temperature. Fourth, the carbon dioxide may be pumped to an evaporator or further heat exchanger where the carbon dioxide absorbs heat from the enclosure so as to provide cooling. The carbon dioxide then may be returned to the compressor so as to repeat the cycle. 
     In order to reduce overall energy costs and reduce the buildup of frost, it is common to cycle the compressor on and off. During the off cycles, however, the pressure across the compressor may come to equilibrium. Such equilibrium may require addition compressor time and energy consumption in order to reestablish a suitable compressor pressure. 
     There is thus a desire for an improved carbon dioxide refrigeration system. Such an improved carbon dioxide refrigeration system may prevent pressure equalization across the high and low pressure sides of the refrigeration system between duty cycles. Avoiding such pressure equalization may result in reduced overall energy consumption and may improve overall system lifetime and availability. 
     SUMMARY OF THE INVENTION 
     The present application and the resultant patent thus provide an expansion device for a refrigeration system. The expansion device may include a multi-way valve with an inlet port, a number of outlet ports, and a selectable valve member movable between a number of open positions related to the outlet ports and a closed position, and a number of capillary tubes in communication with the number of outlet ports. 
     The present application and the resultant patent further provide a carbon dioxide refrigeration system. The carbon dioxide refrigeration system may include a compressor and an expansion device. The expansion device may include a multi-way valve with an inlet port, a number of outlet ports, and a selectable valve member movable between a number of open positions related to the outlet ports and a closed position. The closed position may maintain a pressure differential across the compressor. 
     The present application and the resultant patent further provide an expansion device for a carbon dioxide refrigeration system. The expansion device may include multi-way valve system with an inlet line with a solenoid operated inlet valve and a number of outlet lines with a number of solenoid operated outlet valves, and a number of capillary tubes in communication with the outlet lines. 
     These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a refrigeration system as may be described herein. 
         FIG. 2  is a schematic diagram of a three-way valve for use with an expansion device of the refrigeration system of  FIG. 1  showing an open first capillary tube. 
         FIG. 3  is a schematic diagram of the three-way valve of the expansion device for use with the refrigeration system of  FIG. 1  showing an open second capillary tube. 
         FIG. 4  is a schematic diagram of a three-way valve for use with the expansion device of the refrigeration system of  FIG. 1  showing both capillary tubes closed. 
         FIG. 5  is a schematic diagram of an alternative embodiment of a multi-way valve as may be described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, in which like numerals refer to like elements throughout the several views,  FIG. 1  shows an example of a refrigeration system  100  as may be described herein. The refrigeration system  100  may be used to cool any type of enclosure such as a refrigerator, a cooler, a vending machine, a dispenser, and the like. The overall refrigeration system  100  may have any suitable size or capacity. The refrigeration system  100  also may be applicable to air conditioning and/or heating systems. Although primarily directed towards light commercial or house appliances, the refrigeration system  100  thus may have commercial, industrial, and residential applications. 
     The refrigeration system  100  may include a compressor  110 . The compressor  110  may be a single speed compressor, a two speed compressor, a variable capacity compressor, and the like. The compressor  110  may have any suitable size or capacity. When in operation, the compressor  110  may include an upstream low pressure side  120  and a downstream high pressure side  130  with a pressure differential thereacross. The compressor  110  may compress a refrigerant  140  at high pressure and high temperature. The refrigerant  140  may be a flow of carbon dioxide in a supercritical cycle or in a subcritical cycle depending on the ambient temperature in which it operates and the like. 
     The refrigeration system  100  may include a gas cooler or other type of heat exchanger  150  positioned downstream of the compressor  110 . The heat exchanger  150  may have any suitable size or capacity. The heat exchanger  150  may include a number of coils  160  therein or other type of heat exchange surface. A heat exchanger fan  170  may be positioned adjacent thereto. The heat exchanger fan  170  may be a single speed fan, a variable speed fan, and the like. The heat exchanger  150  may cool the refrigerant  140  by heat exchange with the surrounding environment. 
     The refrigeration system  100  may include an expansion device  180  positioned downstream of the heat exchanger  150 . In this example, the expansion device  180  may include a number of capillary tubes  190 . A first capillary tube  200  and a second capillary tube  210  are shown although any number of the capillary tubes  190  may be used. The capillary tubes  200 ,  210  may be positioned in parallel. The first capillary  200  may offer a low flow path resistance. The second capillary tube  210  may offer a higher flow path resistance. The capillary tubes  190  may be of conventional design and may have any suitable size, shape, or configuration. The use of the capillary tubes  190  in the expansion device  180  reduces both the pressure and the temperature of the refrigerant  140 . The first capillary tube  200  and the second capillary tube  210  may merge at a downstream T-joint  215 . Other components and other configurations may be used herein. 
     The expansion device  180  also may include a multi-way valve  220  positioned upstream of the capillary tubes  190 . In this example, the multi-way valve  220  may be a three-way valve  225  although additional valve ports also may be used herein. The three-way valve  225  thus may include an inlet port  230  positioned downstream of the condenser  150 , a first outlet port  240  in communication with the first capillary tube  200 , and a second outlet port  250  in communication with the second capillary tube  210 . The three-way valve  225  also may include a selectable valve member  260  positioned therein. In this example, the valve member  260  may be in the form of a selection block  270 . Other types of valve members may be used herein. The three-way valve  225  may have any suitable size, shape, or configuration. 
     The three-way valve  225  may have three or more different positions. Specifically, the three-way valve  225  may have a first position  280  as is shown in  FIG. 2 . In the first position  280 , the inlet port  230  is open, the first outlet port  240  is open, and the second outlet port  250  is closed. The three-way valve  225  also may have a second position  290  as is shown in  FIG. 3 . In the second position  290 , the inlet port  230  is open, the first outlet port  240  is closed, and the second outlet port  250  is open. The three-way valve  220  also may have a third or a closed position  300  as is shown in  FIG. 4 . In the third or the closed position  300 , the inlet port  230  is closed, the first outlet port  240  is closed, and the second outlet port  250  is closed. No refrigerant  140  thus flows through the three-way valve  225  in the third or the closed position  300 . A conventional controller may operate the three-way valve  225  according to many different types of operational parameters and the like. Other components and other configurations also may be used herein. 
     The refrigeration system  100  also may include an evaporator  320  or other type of heat exchanger positioned downstream of the expansion device  180 . The evaporator  320  may have any suitable size or capacity. The evaporator  320  may include a number of evaporator coils  330  or other type of heat exchange surface. An evaporator fan  340  may be positioned adjacent thereto. The evaporator fan  340  may be a single speed fan, a variable speed fan, and the like. The refrigerant  140  may be pumped to the evaporator  320  and may absorb heat with a flow of air blown or drawn across the evaporator coils  330  by the evaporator fan  340  so as to cool an enclosure and the like. The refrigerant  140  then may be returned to the compressor  110  to repeat the cycle. Other components and other configurations may be used herein. 
     In use, the expansion device  180  with the multi-way valve  220  and the multiple capillary tubes  190  may accommodate different compressor operating conditions. When the refrigeration system  100  is cooling an enclosure down to its desired temperature, the three-way valve  225  may operate in the first position  280  of  FIG. 2 . Specifically, the first capillary tube  200  with the low flow path resistance is open and the compressor  110  may operate at a high frequency. When the refrigeration system  100  is maintaining an enclosure at a desired temperature, the three-way valve  225  may maneuver to the second position  290  of  FIG. 3 . Specifically, the second capillary tube  210  with a high flow path resistance is open and the compressor  110  may operate at a lower frequency. 
     When the compressor  110  is cycled off, the three-way valve  225  may maneuver to the third or the closed positioned  300  of  FIG. 4 . Specifically, the inlet port  230 , the first outlet port  240 , and the second outlet port  250  are all closed. By completely closing the three-way valve  225 , the refrigerant  140  on the high pressure side  130  of the compressor  110  remains at high pressure while the refrigerant  140  on the low pressure side  120  remains at low pressure with no migration of the refrigerant  140 . Maintaining this pressure differential across the compressor  110  may require some additional torque and power input when the compressor  110  is initially cycled on. The total amount of time that the compressor  110  remains on, however, may be reduced such that the overall energy consumption may be reduced. The use of the three-way valve  225  thus may provide an overall reduction in energy consumption for the compressor  120  and the refrigeration system  100  as a whole. Further, the use of the three-way valve  225  may promote overall system reliability and availability. 
       FIG. 5  shows a further embodiment of a multi-way valve system  350  as may be described herein. The multi-way valve system  350  may include an inlet line  360  with an inlet valve  370  thereon downstream of the heat exchanger  150 . The inlet valve  370  may be an on/off type valve and may be operated by an inlet solenoid  380  and the like. The multi-way valve system  350  may include a T-joint  390  downstream of the inlet valve  370 . The T-joint  390  may lead to a first outlet line  400  with a first outlet valve  410  and to a second outlet line  420  with a second valve  430  thereon. The valves  410 ,  430  may be on/off valves and the like. The first outlet valve  410  may be operated by a first outlet solenoid  440 . The second outlet valve  430  may be operated by a second outlet solenoid  450 . Any number of outlet lines, outlet valves, and outlet valve solenoids may be used herein. The valves may be operated by a controller as described above. Other components and other configurations may be used herein. 
     The multi-way valve system  350  thus may operate in a manner similar to the multi-way valve  220 . With the inlet valve  370  open, either the first outlet line  410  and/or the second outlet line  420  may be used. Closing the inlet valve  370  closes the multi-way valve system  350  entirely so as to maintain the pressure different across the compressor  110  and the like. Other components and other configurations may be used herein. 
     It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.