Patent Publication Number: US-8978410-B2

Title: Refrigerating system having two evaporators performing heat exchange

Description:
TECHNICAL FIELD 
     The present invention relates to a refrigerating system, and more particularly, to a refrigerating system capable of independently cooling a plurality of cooling spaces by using a plurality of evaporators provided at the respective cooling spaces. 
     BACKGROUND ART 
     Generally, a refrigerating system includes a compressor, a condenser, a drier, an expansion device, and an evaporator connected to one another by refrigerant pipes so as to circulate a refrigerant. While passing through the compressor, the condenser, the expansion device, and the evaporator, a refrigerant is compressed, condensed, evaporated, and expanded thereby to perform a cooling operation. 
     In the conventional art, one evaporator is provided, and a process for cooling a plurality of cooling spaces is performed by circulating cool air generated from the evaporator. However, recently, a refrigerating system for independently cooling a plurality of cooling spaces by using a plurality of evaporators is presented. The refrigerating system is applied to a refrigerator. 
     According to the refrigerator, a refrigerant is supplied to one of a plurality of evaporators thus to perform a cooling operation for a cooling space having the evaporator. Here, if the cooling space satisfies a condition preset by a controller, the refrigerant is supplied to another cooling space thus to perform a cooling operation. 
     However, the refrigerating system for independently cooling a plurality of cooling spaces by using a plurality of evaporators has the following problems. After one cooling space is cooled by one evaporator provided thereat, another cooling space is cooled by another evaporator provided thereat. Here, since the respective evaporators have different outlet temperatures from each other, a refrigerant remaining at the one evaporator is not sucked to the compressor at the time of a cooling operation. Accordingly, required is a ‘pump-down’ operation for collecting a refrigerant remaining at an evaporator to a compressor by operating the compressor under a state that refrigerant supply to a plurality of evaporators is blocked. 
     In the refrigerating system for performing a cooling operation by sequentially introducing a refrigerant into a plurality of evaporators, when a refrigerant remains at the evaporators, a cooling operation is performed with a refrigerant deficient by the remaining amount. Accordingly, the entire cooling operation is degraded. The ‘pump-down’ operation is performed to prevent the entire cooling capability from being degraded. 
     Especially, the ‘pump-down’ operation is required at the time of converting a cooling operation from a freezing chamber to a refrigerating chamber. 
     However, the conventional ‘pump-down’ technique has the following problems. First, a refrigerant remaining at the evaporators is collected to the compressor by operating the compressor under a state that refrigerant supply to the evaporators is blocked. Accordingly, as the ‘pump-down’ operation is performed, the compressor may have a lowered suction pressure and discharge occurrence. As a result, the compressor may have damage or a loss. 
     Second, in order to collect a remaining refrigerant to the compressor, a suction pressure of the compressor has to be excessively lowered. Accordingly, high power is required to operate the compressor, thereby degrading the efficiency of the refrigerating system. 
     Third, as the ‘pump-down’ operation is performed, a suction pressure and an outlet pressure of the compressor are lowered, and thus the collected refrigerant may backflow to the evaporator. To solve the problem, a backflow preventing unit is provided between a compressor inlet and an evaporator outlet, thereby increasing the fabrication cost. 
     DISCLOSURE OF THE INVENTION 
     Therefore, it is an object of the present invention to provide a refrigerating system capable of sequentially cooling a plurality of cooling spaces by using evaporators provided at the respective cooling spaces, and collecting a refrigerant without an additional pump-down operation. 
     To achieve these objects, there is provided a refrigerating system, comprising: a first cycle for circulating a refrigerant discharged from a compressor through a first evaporator provided to cool a first cooling space; a second cycle for circulating the refrigerant through a second evaporator provided to cool a second cooling space; a refrigerant supply means for supplying a refrigerant to one of the first cycle and the second cycle; and a heat exchanging unit for performing heat exchange between the first evaporator and the second evaporator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a refrigerating system according to a first embodiment of the present invention; 
         FIG. 2  is a schematic view showing a refrigerating system according to a second embodiment of the present invention; 
         FIG. 3  is a schematic view showing a refrigerating system according to a third embodiment of the present invention; 
         FIG. 4  is a schematic view showing a refrigerating system according to a fourth embodiment of the present invention; 
         FIG. 5  is a schematic view showing a refrigerating system according to a fifth embodiment of the present invention; and 
         FIG. 6  is a schematic view showing a refrigerating system according to a sixth embodiment of the present invention. 
     
    
    
     MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     Hereinafter, a refrigerating system according to a first embodiment of the present invention will be explained in more detail. 
     In the refrigerating system according to the present invention, a plurality of evaporators for respectively cooling a plurality of cooling spaces are provided. The present invention is not limited to a refrigerator having a plurality of cooling spaces such as first, second and third cooling spaces, but can be applied to various types of refrigerating devices and air conditioners. 
     For the understanding of those skilled in the art, the present invention discloses a refrigerating system and a refrigerator having the same. Here, the refrigerating system selectively operates a first cycle to circulate a refrigerant discharged from a compressor through a first evaporator provided to cool a first cooling space, or a second cycle to circulate the refrigerant through a second evaporator provided to cool a second cooling space. 
       FIG. 1  is a schematic view showing a refrigerating system according to a first embodiment of the present invention. 
     Referring to  FIG. 1 , the refrigerating system according to a first embodiment of the present invention comprises a compressor  140  for compressing a refrigerant into a high temperature and high pressure gaseous refrigerant, a condenser  150  for heat-exchanging the gaseous refrigerant compressed by the compressor  140  with ambient air thereby condensing it into a middle temperature and high pressure liquid refrigerant, a drier  160  for removing moisture and impurities included in the condensed refrigerant, a refrigerant supply means  170  for supplying the refrigerant having passed through the drier  160  to an evaporator provided at a cooling space to be cooled, expansion devices  113 ,  123  for expanding and decompressing the refrigerant introduced by the refrigerant supply means  170  into a low temperature and low pressure liquid refrigerant, and first and second evaporators  110 ,  120  for heat-exchanging the liquid refrigerant having passed through the expansion devices  113 ,  123  with ambient air thereby evaporating it as a low temperature and low pressure gaseous refrigerant, and cooling ambient air. 
     In correspondence to the first and second evaporators  110 ,  120 , first and second blowing fans  111 ,  121  for circulating cool air to each cooling space from the first and second evaporators  110 ,  120  are provided. 
     Here, the refrigerant supply means  170  may be implemented as a three-way valve for supplying the refrigerant having passed through the drier  160  to one of the first and second evaporators  110 ,  120 . The refrigerant supply means  170  may be implemented to supply a refrigerant to one of the first and second evaporators  110 ,  120  by turning on/off an open/close valve and flowing a refrigerant on one of the first and second evaporators  110 ,  120 . 
     The refrigerating system according to the first embodiment of the present invention comprises a heat exchanging unit  180  for performing heat exchange between the first and second evaporators  110 ,  120 . 
     The heat exchanging unit  180  may be formed such that a protrusion  112  formed as a part of the first evaporator  110  is extended is positioned near the second evaporator  120 . 
     Preferably, the protrusion  112  is formed as a part of an outlet of the first evaporator  110  is extended. 
     Generally, a ‘pump-down’ operation is performed so as to collect an outlet side refrigerant of one evaporator having a lower temperature than other one or more evaporators. The outlet of the first evaporator  110  is heat-exchanged with the second evaporator  120  thus to have an increased temperature. Accordingly, the outlet side refrigerant of the first evaporator  110  is effectively collected, 
     Preferably, the protrusion  112  is provided with a refrigerant pipe through which a refrigerant flows to the first evaporator  110 . 
     Preferably, the refrigerant pipe of the protrusion  112  is extended from an outlet side refrigerant pipe of the first evaporator  110  so as to pass the refrigerant having been heat-exchanged with air of the first cooling space  117  via the first evaporator  110 . 
     Preferably, the second evaporator  120  is positioned such that an outlet thereof is adjacent to the protrusion  112 . 
     Since an outlet side refrigerant of the second evaporator  120  has a higher temperature than an inlet side refrigerant, it is effectively heat-exchanged with the protrusion  112 . 
     The second evaporator  120  and the protrusion  112  may be provided to be adjacent to each other with a gap wide enough to generate heat exchange therebetween. The second evaporator  120  and the protrusion  112  may be provided to come in contact with each other. 
     In the above configuration, a temperature difference between each outlet side refrigerant of the first and second evaporators  110 ,  120  is small, thereby to collect remaining refrigerant without a ‘pump-down’ operation. 
     Preferably, one refrigerator having a larger load between the first and second evaporators  110 ,  120  is referred to as the first evaporator  110 , and another having a smaller load between the first and second evaporators  110 ,  120  is referred to as the second evaporator  120 . 
     Preferably, one evaporator provided to cool a freezing chamber of a refrigerator is referred to as the first evaporator  110 , and another evaporator provided to cool a chilling chamber of the refrigerator is referred to as the second evaporator  120 . 
     Referring to  FIG. 1 , reference numeral  151  denotes a condensing fan for discharging heat from the condenser  150 . 
     Hereinafter, the operation of the refrigerating system according to the first embodiment of the present invention will be explained. 
     First, refrigerant compressed by the compressor  140  is heat-exchanged with external air via the condenser  150  thus to be condensed. Then, the condensed refrigerant is introduced into the drier  160  connected to the condenser  150  through a pipe. Here, as moisture and impurities included in the condensed refrigerant are filtered by the drier, pure refrigerant is obtained. Then, the refrigerant having passed through the drier  160  is introduced into the expansion device  113  by the refrigerant supplying unit  170 , is introduced into the first evaporator  110  thus to cool the first cooling space  117 , and is fed back to the compressor  140 . Once the first cooling space  117  has a temperature preset by a user, a refrigerant is supplied to the expansion device  123  and the second evaporator  120  by the refrigerant supply means  170  thus to start to cool the second cooling space  127 . Here, a refrigerant having not been collected to the compressor  140  remains at the first evaporator  110 . The refrigerant remaining at the first evaporator  110  is heat-exchanged with a refrigerant passing through the second evaporator  120  by the heat exchanging unit  180 . Accordingly, a temperature difference between the refrigerant remaining at the first evaporator  110  and the refrigerant remaining at the second evaporator  120  becomes small, thereby collecting the refrigerant remaining at the first evaporator  110  to the compressor  140 . Therefore, an additional ‘pump-down’ operation is not required. 
     Hereinafter, the operation of the refrigerating system according to a second embodiment of the present invention will be explained. Explanation for the same parts as those of the first embodiment will be omitted. 
       FIG. 2  is a schematic view showing a refrigerating system according to a second embodiment of the present invention. 
     Referring to  FIG. 2 , the refrigerating system according to a second embodiment of the present invention comprises a first evaporator  210 , a second evaporator  220 , and a heat exchanging unit  280  for performing heat exchange between the first and second evaporators  210 ,  220 . 
     The heat exchanging unit  280  may be formed such that a protrusion  222  formed as a part of the second evaporator  220  is extended is positioned near the first evaporator  210 . 
     Preferably, the heat exchanging unit  280  is formed such that an outlet of the first evaporator  210  is positioned near the protrusion  222 . 
     The reason is in order to increase a temperature of an outlet side refrigerant of the first evaporator  210  thereby to effectively collect the refrigerant. 
     The protrusion  222  is provided with a refrigerant pipe through which a refrigerant flows to the second evaporator  220 . 
     Preferably, the refrigerant pipe of the protrusion  222  is formed as an outlet side refrigerant pipe of the second evaporator  220  is extended, thereby passing a refrigerant having been heat-exchanged with air of the second cooling space  227 . 
     In the above configuration, the refrigerant flowing on the protrusion  222  has a temperature higher than that of an inlet side refrigerant of the second evaporator  220 . Accordingly, the refrigerant passing through the first evaporator  210  that performs heat-exchange with the second evaporator  220  has a higher temperature, thereby being effectively collected. 
     In the refrigerating system according to the second embodiment of the present invention, a refrigerant remaining at the first evaporator  210  is heat-exchanged with a refrigerant passing through the second evaporator  220  by the heat exchanging unit  280 . By the heat-exchange, a temperature difference between the refrigerant remaining at the first evaporator  210  and the refrigerant passing through the second evaporator  220  becomes small. Accordingly, the refrigerant remaining at the first evaporator  210  is collected to the compressor  240 , thereby requiring no ‘pump-down’ operation. 
     Hereinafter, the operation of the refrigerating system according to a third embodiment of the present invention will be explained. Explanation for the same parts as those of the first embodiment will be omitted. 
       FIG. 3  is a schematic view showing a refrigerating system according to a third embodiment of the present invention. 
     Referring to  FIG. 3 , the refrigerating system according to a third embodiment of the present invention comprises a first evaporator  310 , a second evaporator  320 , and a heat exchanging unit  380  for performing heat exchange between the first and second evaporators  310 ,  320 . 
     The heat exchanging unit  380  may be formed such that an outlet side refrigerant pipe of the second evaporator  320  winds the first evaporator  310  one or more times. 
     Here, the outlet side refrigerant pipe of the second evaporator  320  may wind an outlet of the first evaporator  310 . In order to enhance heat-exchange efficiency, heat radiating fins of the first evaporator  310  may be formed to contact the outlet side refrigerant pipe of the second evaporator. 
     In the refrigerating system according to the third embodiment of the present invention, a refrigerant remaining at the first evaporator  310  is heat-exchanged with a refrigerant passing through the second evaporator  320  by the heat exchanging unit  380 . By the heat-exchange, a temperature difference between the refrigerant remaining at the first evaporator  310  and the refrigerant passing through the second evaporator  320  becomes small. Accordingly, the refrigerant remaining at the first evaporator  310  is collected to the compressor  340 , thereby requiring no ‘pump-down’ operation. 
     Hereinafter, the operation of the refrigerating system according to a fourth embodiment of the present invention will be explained. Explanation for the same parts as those of the first embodiment will be omitted. 
       FIG. 4  is a schematic view showing a refrigerating system according to a fourth embodiment of the present invention. 
     Referring to  FIG. 4 , the refrigerating system according to a fourth embodiment of the present invention comprises a first evaporator  410 , a second evaporator  420 , and a heat exchanging unit  480  for performing heat exchange between the first and second evaporators  410 ,  420 . 
     The heat exchanging unit  480  may be formed such that an outlet side refrigerant pipe of the second evaporator  420  winds an outlet side refrigerant pipe of the first evaporator  410  one or more times. 
     In order to enhance heat-exchange efficiency, heat radiating fins that share the refrigerant pipes disposed at each outlet of the first and second evaporators  410 ,  420  may be provided. 
     In the refrigerating system according to the fourth embodiment of the present invention, a refrigerant remaining at the first evaporator  410  is heat-exchanged with a refrigerant passing through the second evaporator  420  by the heat exchanging unit  480 . By the heat-exchange, a temperature difference between the refrigerant remaining at the first evaporator  410  and the refrigerant passing through the second evaporator  420  becomes small. Accordingly, the refrigerant remaining at the first evaporator  410  is collected to the compressor  440 , thereby requiring no ‘pump-down’ operation. 
     Hereinafter, the operation of the refrigerating system according to a fifth embodiment of the present invention will be explained. Explanation for the same parts as those of the first embodiment will be omitted. 
       FIG. 5  is a schematic view showing a refrigerating system according to a fifth embodiment of the present invention. 
     Referring to  FIG. 5 , the refrigerating system according to a fifth embodiment of the present invention comprises a first evaporator  510 , a second evaporator  520 , and a heat exchanging unit  580  for performing heat exchange between the first and second evaporators  510 ,  520 . 
     The heat exchanging unit  580  may be formed such that an outlet side refrigerant pipe of the first evaporator  510  winds an outlet of the second evaporator  520  one or more times. In order to enhance heat-exchange efficiency, heat radiating fins of the second evaporator  520  may be formed to contact the outlet side refrigerant pipe of the first evaporator  510 . 
     In the refrigerating system according to the fifth embodiment of the present invention, a refrigerant remaining at the first evaporator  510  is heat-exchanged with a refrigerant passing through the second evaporator  520  by the heat exchanging unit  580 . By the heat-exchange, a temperature difference between the refrigerant remaining at the first evaporator  510  and the refrigerant passing through the second evaporator  520  becomes small. Accordingly, the refrigerant remaining at the first evaporator  510  is collected to the compressor  540 , thereby requiring no ‘pump-down’ operation. 
     Hereinafter, the operation of the refrigerating system according to a sixth embodiment of the present invention will be explained. Explanation for the same parts as those of the first embodiment will be omitted. 
       FIG. 6  is a schematic view showing a refrigerating system according to a sixth embodiment of the present invention. 
     Referring to  FIG. 6 , the refrigerating system according to a sixth embodiment of the present invention comprises a first evaporator  610 , a second evaporator  620 , and a heat exchanging unit  680  for performing heat exchange between the first and second evaporators  610 ,  620 . 
     The heat exchanging unit  680  may be formed such that an outlet side refrigerant pipe of the first evaporator  610  winds an outlet side refrigerant pipe of the second evaporator  620  one or more times. 
     In order to enhance heat-exchange efficiency, heat radiating fins that share the refrigerant pipes disposed at each outlet of the first and second evaporators  610 ,  620  may be provided. 
     In the refrigerating system according to the sixth embodiment of the present invention, a refrigerant remaining at the first evaporator  610  is heat-exchanged with a refrigerant passing through the second evaporator  620  by the heat exchanging unit  680 . By the heat-exchange, a temperature difference between the refrigerant remaining at the first evaporator  610  and the refrigerant passing through the second evaporator  620  becomes small. Accordingly, the refrigerant remaining at the first evaporator  610  is collected to the compressor  640 , thereby requiring no ‘pump-down’ operation. 
     The refrigerating system according to the present invention has the following advantages. 
     First, heat exchange is performed between the first and second evaporators by the heat exchanging unit. Accordingly, the first and second evaporators have temperatures similar to each other, thereby requiring no additional ‘pump-down’ operation. 
     Second, the compressor does not have a discharge occurrence owing to no additional ‘pump-down’ operation, thereby having no loss and an enhanced reliability. 
     Third, since no additional pump-down operation is required, power consumption for operating the compressor so as to collect a remaining refrigerant is reduced. Accordingly, the efficiency of the refrigerating system is enhanced. 
     It will also be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.