Patent Publication Number: US-6666043-B2

Title: Dewfall preventing device of refrigerator

Description:
This application claims the benefit of the Korean Application Nos. P 2002-0027699, P 2002-25099, P 2002-25100 filed on May 20, 2002, May 7, 2002, May 7, 2002, which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a refrigerator, and more particularly, to a dewfall preventing device of a refrigerator for preventing the dewfall phenomenon occurring on the contact portion of the front side and a door of the refrigerator by the hot heat of a compressor of the refrigerator. 
     2. Discussion of the Related Art 
     Generally, a refrigerator is used to freeze or cool foods, and its schematic structure is illustrated as follows. 
     FIG. 1 illustrates a side sectional view of a conventional refrigerator. 
     Referring to FIG. 1, a refrigerator includes a case forming a receiving space divided into a freezing room  101  and a cooling room  102 , a door  12 , which is installed on the front side of the case  10  to open/close the freezing room  101  and the cooling room  102 , and units such as a compressor  20 , a condenser  30 , and an evaporator  40 , etc. to form a freezing cycle. 
     In the refrigerator, a gas refrigerant of low pressure and temperature is compressed into high pressure and temperature by the compressor  20 , and the compressed gas refrigerant of high pressure and temperature is transferred into a liquid phase of high pressure by being cooling-compressed while passing the condenser  30 . While the liquid phase of the refrigerant of high pressure passes through a capillary tube or an expander (not shown), its temperature and pressure are decreased. While the liquid refrigerant is transferred into a gas of low pressure and temperature in the evaporator  40 , it extracts the heat from the cooling room and the freezing room to cool the air there inside. 
     The evaporator  40  is installed inside a vaporizing room  103  that is a separate space of the back of the freezing room  101 . The air cooled by the evaporator  40  is introduced into the freezing room  101  and the cooling room  102  and circulated therethrough by the operation of the fan  50  installed in the vaporizing room  103  to drop the temperature of the freezing room  101  and the cooling room  102 . 
     Generally, dew forms on the front end side of the case  10  which contacts the door  12  due to the temperature difference with the outside when opening the door  12  of the refrigerator because of the characteristics of the freezing room  101 , which is referred to as dewfall phenomenon. 
     To prevent the above dewfall phenomenon, a hot line (referring a numeral  70  of FIG. 2) is normally installed in the refrigerator. 
     FIG. 2 illustrates a flow line of the hot line of the conventional refrigerator. 
     Referring to FIG. 2, the hot line (dotted line)  70  comes out from an input end of the condenser  30  installed in a machinery room, circulates the case  10 , and goes into the output end of the condenser  30 . That is, the hot line  70  is a secondary condensing tube installed on the interior front side of the case  10 , which circulates the contact portion of the door  12  and the case  10 . 
     Therefore, according to the conventional technology, a part of the refrigerant gas of high pressure and temperature discharged from the compressor  20  is introduced into the hot line  70 . Then, the front side portion around the hot line  70  in the case  10  is heated over a room temperature thereby to prevent the dewfall phenomenon on the front side of the case  10  even with the opening of the door  12 . 
     However, a cooling load is increased in the conventional refrigerator, that is, the refrigerant gas of high pressure and temperature discharged from the compressor  20  is used as the working fluid of the hot line  70 , and the overall front side of the case  10  is heated over a high temperature unnecessarily, and the heat generated from the hot line  70  is transferred into the freezing room  101  and the cooling room  102 . 
     In addition, a frictional heat of a high temperature is generated from the compressor  20 , and the frictional heat has a bad effect on the compressor  20 , itself thereby to reduce the operation performance of the compressor  20 . 
     In addition, the heat generated from the compressor  20  is not used appropriately, and wasted to the outside resulting in causing a loss of energy and reducing the efficiency of the refrigerator. 
     In addition, besides the circulation cycle of the refrigerant basically incorporating only the compressor  20 , the condenser  30 , the evaporator  40 , and the expansion valve in the conventional technology, the additional refrigerant is necessary by the amount passing through the hot line  70  so that the production expenses is increased and the productivity of the refrigerator is decreased. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a dewfall preventing device of a refrigerator that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a dewfall preventing device of a refrigerator by using a thermosyphon employing the hot heat generated from a compressor of the refrigerator as a heating source, and forming a hot line on the contact portion of a refrigerator case and a refrigerator door. 
     Another object of the present invention is to provide a dewfall preventing device of a refrigerator for efficiently discharging the hot heat generated from the compressor. 
     A further object of the present invention is to provide a dewfall preventing device of a refrigerator, wherein the thermosyphon is operated by a working fluid independently from a typical refrigerating cycle of the refrigerator, and the separate working fluid heat-exchanges with the heat of the cooling oil of the compressor. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a dewfall preventing device of a refrigerator may include a compressor for compressing a refrigerant; a heat exchanger for extracting the heat generated from the increase of the refrigerant inner energy by the friction and the compression in the compressor; a thermosyphon for maintaining the contact portion of a refrigerator case and a refrigerator door at a predetermined temperature by a way that a working fluid phase-transferred into a gas phase in the heat exchanger radiates the extracted heat, and after releasing the extracted heat, the cooled working fluid comes back into the heat exchanger by gravitation; and a wick being placed in the pipe line of the heat exchanger for concentrating the extracted heat generated from the compressor and enabling the working fluid to easily flow. 
     The present invention forms a hot line by using thermosyphon in which a separate working fluid is injected without using a refrigerant gas, and reduces an air pollution due to the refrigerant gas. In addition, the production process to realize the present invention is simple without an auxiliary circulating device. 
     Additionally, the compressor is easily cooled, and the waste heat is reused thereby to increase energy efficiency. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
     FIG. 1 is a side sectional view of a conventional refrigerator; 
     FIG. 2 illustrates the hot line used in the conventional refrigerator; 
     FIG. 3 illustrates that a dewfall preventing device is installed in the refrigerator according to one embodiment of the present invention; 
     FIG. 4 illustrates a heat exchanger according to one embodiment of the present invention; 
     FIG. 5 illustrates the operation of the dewfall preventing device to vaporize dew according to one embodiment of the present invention; 
     FIG. 6 illustrates that a dewfall preventing device is installed in the refrigerator according to another embodiment of the present invention; 
     FIG. 7 is a sectional view of a heat exchanger according to another embodiment of the present invention; 
     FIG. 8 illustrates a structure of the hot line used in a refrigerator comprising a pair of a freezing room and a cooling room according to another embodiment of the present invention; 
     FIG. 9 illustrates that a dewfall preventing device is installed in the refrigerator according to another embodiment of the present invention; 
     FIG. 10 is a sectional view of a heat exchanger and a compressor according to another embodiment of the present invention; 
     FIG. 11 is a sectional view of a heat exchanger of a thermosyphon according to another embodiment of the present invention; and 
     FIG. 12 illustrates a structure of the hot line used in a refrigerator comprising a pair of a freezing room and a cooling room according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     The preferred embodiments of the present invention all employ a way of thermosyphon in the dewfall preventing device of a refrigerator. 
     The thermosyphon is a thermal circulation structure in which a working fluid is injected into the inner space of a closed case of a vacuum state, and the working fluid in the inner space is vaporized by heating one end of the thermosyphon, and the working fluid moves to the other side by the pressure difference generated by the evaporation. The working fluid radiates heat to the around and is again back to the liquid state during the compression process. The liquid phase of the working fluid comes back to the thermosyphon by gravitation. 
     FIG. 3 illustrates that a dewfall preventing device is installed in the refrigerator according to one embodiment of the present invention, and FIG. 4 illustrates a heat exchanger according to one embodiment of the present invention. 
     Referring to FIGS. 3 and 4, the present invention is illustrated as follows. 
     The working fluid is vaporized by the waste heat of a compressor  20  inside a heat exchanger  80 , which is phase-transferred from liquid to gas. The phase-transferred working fluid moves along a hot line  70  placed on the front side of a case  10  of the refrigerator and radiates heat. 
     The heat of the working fluid vaporizes and removes the dew from the contact portion of the case  10  and a door  12  of the refrigerator, normally operated by the temperature difference in and out of the refrigerator, and the working fluid is phase-transferred from gas to liquid by the compression. The working fluid in a liquid phase falls down back into the heat exchanger  80  by gravitation. 
     The present invention provides a device to prevent dew from forming on the contact portion of the case  10  and the door  12  by one directional circulation of the vaporization and the compression of the working fluid. The detailed inner structure of the present invention is illustrated as follows. 
     The heat exchanger  80  which is installed on the lower side of the compressor  20 , concentrates the waste heat transferred from the compressor  20 , and forces the working fluid, which heat-exchanges with the waste heat of the compressor  20 , to be discharged into the hot line  70 . 
     As shown in FIG. 4, the heat exchanger  80  includes a hollow outer housing  81 , a wick part  82 , which is placed inside the hollow outer housing  81 , and concentrates the waste heat transferred from the compressor  20 , and then forces the working fluid, which heat-exchanges the heat, to be easily discharged to the hot line  70 , and further includes a fluid inflow pipe line  83  and a fluid outflow pipe line  84 , which are placed on the inner/outer side of the outer housing  81 , and through which the working fluid is introduced into the outer housing  81 , and then the working fluid exchanges heat via the wick part  82 , and is discharged into the hot line  70 . 
     Particularly, the fluid inflow pipe line  83  and the fluid outflow pipe line  84 , as shown in FIG. 4, have a different length. The structure allows one directional movement of the working fluid which is introduced into the outer housing  81  and exchanges the heat from the compressor  20  while passing through the wick part  82  without flowing back so that the waste heat from the compressor  20  is sufficiently transferred to the working fluid, and is discharged into the hot line  70  through the fluid outflow pipe line  84 . To achieve this purpose, the fluid inflow pipe line  83  is extended inside the heat exchanger  80  and the wick part  82  with a predetermined length, and the fluid outflow pipe line  84  is placed on the outer side of the heat exchanger  80 . 
     Preferably, an inflow port of the fluid inflow pipe line  83  is formed inside the heat exchanger  80  on the opposite side of the fluid outflow pipe line  84 , and more preferably, is formed far away from the fluid outflow pipe line  84 . 
     The wick part  82 , which is placed inside the heat exchanger  80 , is formed of a mesh structure to concentrate the waste heat transferred from the compressor  20 , and to force the working fluid which exchanges the waste heat with the compressor  20  to be discharged into the hot line  70   
     The discharge of the heat-exchanged working fluid into the hot line  70  is accelerated when the pressure of the working fluid passing through the wick part  82  is decreased, and the flow velocity of the working fluid is increased by the capillary phenomenon which occurs in the wick part  82  by the surface tension of the working fluid introduced into the heat exchanger  80 . 
     The hot line  70 , as shown in FIG. 3, is figured such that a predetermined diameter of a pipe is connected to the heat exchanger  80 , and installed on the front side of the case  10  with a closed loop shape. In the hot line  70 , the heat of the working fluid vaporizes and removes the dew from the front side of the case  10  of the refrigerator operated by the temperature difference in and out of the refrigerator by the radiation of the working fluid, and the working fluid is phase-transferred from gas to liquid by the compression. 
     The working fluid in a liquid phase falls down back into the heat exchanger  80  by gravitation to complete one directional circulation with the heat-exchange of the waste heat concentrated in the wick part  82  from the compressor  20 , and prevents the dew from forming on the contact portion of the case  10  and the door  12 . 
     The working liquid functions separately from the refrigerant which is necessary to generate the cold for the refrigerating cycle. In more detail, the working liquid heat-exchanges with the waste heat from the compressor  20 , which is concentrated into the heat exchanger  80 , is phase-transferred from liquid to gas, and circulates to move along the hot line  70 , and vaporizes the dew on the contact portion of the case  10  and the door  12  of the front side of the case  10  by the radiation so as to be phase-transferred from gas to liquid. 
     The working liquid of the present invention is filled in a vacuum state, and includes a water or methyl alcohol, etc., which is vaporized and condensed easily at a temperature of 0-70° C. 
     The function of the dewfall preventing device of the refrigerator of the present invention is illustrated as follows. 
     FIG. 5 illustrates the operation of the dewfall preventing device to vaporize dew according to one embodiment of the present invention. 
     Referring to FIG. 5, the waste heat of the compressor  20 , itself is transferred to the working fluid separately from the refrigerant to prevent the dew from forming on the contact portion of the case  10  and the door  12 . 
     The waste heat of the compressor  20  is the heat generated when the refrigerant is compressed inside the compressor  20  to be phase-transferred to a gas state of high pressure and temperature. The heat-exchanged working fluid radiates the heat while passing along the hot line  70  installed on the front side of the refrigerator to vaporize dew forming on the contact portion of the case  10  and the door  12 . 
     Along the moving order of the heat and the working fluid, a detailed description of the operation of the embodiment will be made below. 
     A high temperature of heat is generated in the compressor  20 , itself by the load when the refrigerant liquid of low pressure and temperature is compressed into the refrigerant gas of high pressure and temperature. The high temperature of the heat in the compressor  20  is transferred to the wick part  82  of the heat exchanger  80  installed on the lower side of the compressor  20 , and the waste heat is concentrated in the wick part  82 . 
     The fluid inflow pipe line  83  and the fluid outflow pipe line  84  are connected to the heat exchanger  82  including the waste heat of the compressor  20 , and form a closed loop with the hot line  70 . The working fluid is filled inside the hot line  70  and flows there through. The working fluid is introduced through the fluid inflow pipe line  83  of the heat exchanger  80  to reach down to the other end of the heat exchanger  80 , opposite to the fluid inflow pipe line  83 . 
     The working fluid heat-exchanges with the waste heat of the compressor  20  concentrated in the wick part  82  while passing through the wick part  82  of the heat exchanger  80 , and vaporizes from a liquid phase to a gas phase. 
     The working fluid phase-transferred to a gas phase is discharged through the fluid outflow pipe line  84  of the heat exchanger  80 . 
     As the fluid inflow pipe line  83  and the fluid outflow pipe line  84  are placed on the opposite sides of the heat exchanger  80 , the working fluid introduced into the heat exchanger  80  does not flow back into the fluid inflow pipe line  83 , passes through the wick part  82  including the waste heat of the compressor  20 , extracts the waste heat of the compressor  20 , and is discharged through the fluid outflow pipe line  84  of the heat exchanger  80 . 
     The discharged working fluid moves along the hot line  70  installed on the front side, the case  10  of the refrigerator as a closed loop shape, and radiates the heat to vaporize and remove the dew forming on the contact portion of the case  10  and the door  12 . The working fluid goes through a condensation which is phase-transferred from gas to liquid. 
     The working fluid of a liquid phase, which is phase-transferred by the condensation, and falls down back to the heat exchanger  80  by gravitation, and the introduced working fluid again heat-exchanges with the waste heat of the compressor  20 , which is concentrated into the wick part  82 , to establish one circulation cycle. 
     The heat exchanger  80  illustrated in the drawings of the present invention is placed on the lower side of the compressor  20 , but may be placed on either the upper side or the lateral side of the compressor  20  only if its structure allows the heat-exchange with contacted to the compressor  20 . 
     As set forth before, the working fluid goes through the vaporization and the condensation sequentially during one cycle, and extracts and radiates heat during the phase transfer to prevent the dew from forming on the contact portion of the case  10  and the door  12 . 
     The heat transferring way of the thermosyphon of the embodiment of the present invention is employed in the heat exchanger and the hot line to prevent the dew from forming on the contact portion of the case  10  and the door  12 . 
     In addition, as the waste heat of the compressor is radiated when the waste heat generated from the compressor is transferred to the working fluid, the efficiency of the compressor and the refrigerating cycle are increased. 
     The first embodiment of the present invention shows the case of a single freezing room and a single cooling room, but it may be employed in the refrigerator comprising a pair of the freezing room and the cooling room on its both sides, right and left, wherein the outflow pipe line is divided into two lines, introduced into the right and left sides, each forming a closed loop, joined into the end of the inflow pipe line, and introduced into the heat exchanger by one single inflow pipe line. 
     Now herein after, another embodiment of the present invention is illustrated. 
     FIG. 6 illustrates that a dewfall preventing device is installed in the refrigerator according to another embodiment of the present invention. 
     Referring to FIG. 6, a structure of the dewfall preventing device of the refrigerator includes a heat exchanger  240  placed in the machinery room of the rear of the refrigerator, an outflow pipe line  201  formed on the upper side of the heat exchanger  240 , and a hot line  70  expanded from the outflow pipe line  201  and placed on the front side of the refrigerator, and an inflow pipe line  202  being connected to the end of the hot line  70  and placed on the lower side of the heat exchanger  210 . 
     The heat circulation cycle formed of the heat exchanger  210  and the hot line  270  is integrally formed with the thermosyphon  200  as a heat transferring device of a closed loop to enable a large amount of heat to be transferred even by a little temperature difference. 
     The working fluid  220  includes water or methyl alcohol, and vaporization and condensation occur at a low temperature of 0-70° C. in a vacuum state. 
     FIG. 7 is a sectional view of the heat exchanger of the embodiment of the present invention, and more detailed description will be made referring to the drawing of the heat exchanger in FIG.  6 . 
     Referring to FIG. 7, the heat exchanger  240  is figured in that a double shell  250  has an outflow pipe line  201  on its upper side, and the inflow pipe line  202  on its lower side, a compressor  210  placed to maintain a predetermined interval of a space  260  from the inner wall of the double shell  250 , a wick  230  filling the space  260  between the compressor  210  and the double shell  250 , and a working fluid  220  moving upward by the capillary phenomenon by the wick  230 , and the working fluid being heated and vaporized by the heat exchanger  240 . 
     The compressor  210  keeps a high temperature of the frictional heat generated by the friction of moving parts such as a piston and a cylinder, etc. during the compression process of the refrigerant gas. 
     The working fluid  220  in the heat exchanger  240  is heated and vaporized by the heat generated from the compressor  20 , and the vaporized working fluid  220  moves to the upper side of the heat exchanger  240  by the pressure difference. 
     The wick  230  is a capillary structure to move upward the working fluid  220  in a liquid state before vaporization. 
     FIG. 8 illustrates the hot line  70  used in the refrigerator comprising a pair of the freezing room and the cooling room. The outflow pipe line  201  is extended from one point of the heat exchanger  240 , and the working fluid, which is heated in the heat exchanger  240  and vaporizes, is discharged through the outflow pipe line  201 . The outflow pipe line  201  is extended to the hot line  70 , each of the hot line  70  being formed on the front right and left sides of the refrigerator, and the hot line  70  passing each freezing room and each cooling room of the right and left sides is joined to the inflow pipe line  202  of the heat exchanger  240 . 
     With a structure as above, the operation of the dewfall preventing device of the refrigerator of the present invention is illustrated as follows. 
     First, a compressor  20  is provided to have the space  260  with distanced away from the inner wall of the double shell  250 , and the space  260  has the working fluid  220  and the wick  230  filled there inside. 
     Water or methyl alcohol may be used as the working fluid  220 , and water or methyl alcohol can transfer a large amount of heat just by a small temperature difference by vaporization and condensation at a temperature of 0-70° C. in a vacuum state. 
     The working fluid  220  having material characteristics as above is heated by the heat generated from the compressor, and the heated working fluid  220  is vaporized to move upward and through the outflow pipe line on the upper side of the heat exchanger, and passes the hot line  70  formed on the front side of the refrigerator. 
     While passing through the hot line  70 , the working fluid  220  radiates heat and is condensed. 
     The condensed liquid state of the working fluid  220  moves downward by gravitation, and comes back into the inflow pipe line  202  of the heat exchanger  240  thereby to repeat the above process and form the heat circulation cycle. 
     As the present invention illustrated as above uses the hot line incorporating the thermosyphon not by refrigerant gas, it contributes to decreasing the destruction of the ozone layer, and also makes it possible to easily and efficiently install the thermosyphon without a separate circulation device. 
     In addition, the heat generated from the compressor is reused as a heating source to operate the thermosyphon thereby to increase the thermal efficiency. 
     In addition, the present invention provides an effect to cool down the compressor directly by the working fluid which heat-exchanges with the compressor surrounded thereby. 
     Another embodiment of the present invention is illustrated with reference to the drawings as follows. 
     FIG. 9 illustrates a dewfall preventing device of the refrigerator according to another embodiment of the present invention. 
     Referring to FIG. 9, the hot line  70  of the embodiment of the present invention uses thermosyphon as a heat transferring device to enable a large amount of heat to be transferred even by a small temperature difference. 
     The working fluid  220  includes water or methyl alcohol, and vaporization and condensation occur at a low temperature of 0-70° C. in a vacuum state. 
     FIG. 10 is a sectional view of the heat exchanger and the compressor of the embodiment of the present invention. 
     Referring to FIG. 10, the compressor  20  includes a sealed type compressor  20  which is normally used in the refrigerator. 
     A high temperature of heat is generated by the friction of the inner wall of the cylinder  26  and the piston  25  during the compression process of the compressor  20 , and a cooling oil  21  is used to cool the friction heat and to lubricate the operational parts. 
     The cooling oil  21  follows a repeated circulation process wherein it is pumped by a typical pumping means, and supplied to the inside of the compressor  20  to lubricate and cool and comes back into the storage part. 
     However, the temperature of the cooling oil  21  is gradually increased during the repeated process as above, and the cooling efficiency is decreased. 
     Therefore, the present invention uses the heated cooling oil  21  as a heat exchanger  310  to heat the thermosyphon  300 , and accordingly, decreases the temperature of the cooling oil and improves the cooling efficiency of the compressor. 
     The low temperature of a working fluid  320  in the thermosyphon  300  is introduced into a lower line  302  and heat-exchanges with the heat of the cooling oil  21  in high temperature, and moves to a upper line  301 . The cooling oil  21  transfers the heat to the working fluid  320 , and decreases its temperature. The working fluid  320  is heated by the heat of the cooling oil  21 . 
     The working fluid  320  is vaporized into a gas, and moves to the hot line  70  of the front side of the refrigerator. While passing through the hot line  70 , it radiates the heat to the around. As a result, the contact portion of the refrigerator case and the door is heated by an appropriate temperature, and the working fluid transferring the heat is condensed, and moves down to the lower side by gravitation, and is introduced into the lower line  302 . 
     FIG. 11 is a sectional view of the heat exchanger of the thermosyphon according to the embodiment of the present invention. 
     Referring to FIG. 11, a capillary fibrous wick  330  is formed inside the thermosyphon  300  inserted into the compressor  20 . The working fluid extracts the heat of the compressor from the wick  330 , and vaporizes. The vaporized working fluid radiates the heat on the contact portion of the case  10  and the door  12 , and is condensed into a liquid state. Then, it is back into the lower line  302  of the heat exchanger  310  by gravitation. 
     The working fluid  320  back into the lower line  302  of the heat exchanger  310  moves up to the upper line  301  by the capillary phenomenon of the wick  330  in the heat exchanger  310 . The working fluid  320  up to the upper line  301  is vaporized and the vaporized working fluid  320  circulates the hot line  70  formed on the front side of the refrigerator. 
     FIG. 12 shows the dewfall preventing device of the refrigerator according to another embodiment of the present invention. 
     Referring to FIG. 12, the hot line  70  is employed on the refrigerator having the freezing room and the cooling room on the right and left sides. The upper line  301  is divided from one point, and the working fluid  320  heated by the heat exchanger  310  is vaporized and discharged there through. The upper line  301  reaches each of the hot line  70  to circulate the front side of each of the freezing room  101  and the cooling room  102 , and each hot line  70  circulates each of the freezing room  101  and the cooling room  102 , and is joined to the lower line  302  of the heat exchanger  310 . 
     The present invention as above forms the hot line by using thermosyphon with the injected working liquid separately from the cooling gas. Therefore, the air pollution due to the usage of the cooling gas can be decreased. 
     In addition, according to the present invention, the production process becomes simple because it can be easily installed without an auxiliary circulation device. 
     In addition, the waste heat of the cooling oil used to cool the compressor is used as a heating source to operate the thermosyphon thereby to efficiently cool the compressor by the working fluid. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.