Patent Publication Number: US-2011059346-A1

Title: Cooling system and battery cooling system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Application No. 10-2009-0083985, filed in the Korean Intellectual Property Office on Sep. 7, 2009, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a heated member cooling system for prevention of overheating of a heated member including a battery cell, a fuel cell, a semiconductor chip or the like. 
     2. Description of the Related Art 
     A battery or fuel cell used in a high-output device, such as an automobile or the like, may overheat due to having high heating value. In such circumstances, it may be necessary to supply the battery or fuel cell with a cooling device to prevent overheating. It may be inadequate to cool a heated member having a high heating value using a cooling device of an air cooling type, and mainly, the heated member may be cooled by using a cooling device of a liquid cooling type. Thus, it is necessary to consider efficiency of a cooling system of a liquid cooling type. 
     SUMMARY 
     Aspects of the present invention include a cooling system and a battery cooling system that include a heat pipe and a heat exchanger of a liquid cooling type, whereby cooling efficiency is improved. 
     Aspects of the present invention also include a cooling system and a battery cooling system having structures simplified to be manufactured in a compact manner. 
     According to an aspect of the present invention, a cooling system is provided. The cooling system includes at least one heat source; at least one heat pipe including, on one side, a heat absorbing part contacting the at least one heat source to absorb heat from the heated member, and on another side, a heat emitting part to emit the heat absorbed by the heat absorbing part; a first heat exchange unit to contain a refrigerant heated by absorbing the heat from the heat emitting part; and a second heat exchange unit to receive the refrigerant from the first heat exchange unit and cooling the refrigerant, and to emit the cooled refrigerant to the first heat exchange unit. 
     According to another aspect of the present invention, the refrigerant in a liquid state may be partly vaporized in the first heat exchange unit, and the partly vaporized refrigerant may be condensed into a liquid again in the second heat exchange unit. 
     According to another aspect of the present invention, the at least one heat source may include a flat surface, and the heat absorbing part of the heat pipe may include a flat surface in surface contact with the flat surface of the at least one heat source. 
     According to another aspect of the present invention, the at least one heat pipe may have a plate shape. 
     According to another aspect of the present invention, the at least one heat source may comprise a plurality of the heat sources separated from each other, and the at least one heat pipe may include a plurality of the heat pipes, and each of the plurality of the heat pipes may be interposed between corresponding ones of the plurality of the heat sources. 
     According to another aspect of the present invention, a plurality of the heat emitting parts of the plurality of the heat pipes may be separated from each other, and each of the plurality of the heat emitting parts may be inserted into the first heat exchange unit, and each of the plurality of the heat emitting parts may directly contact the refrigerant. 
     According to another aspect of the present invention, the heat emitting part may be bent and extended from the heat absorbing part, and a side surface of the heat emitting part may be in contact with an external side surface of the first heat exchange unit. 
     According to another aspect of the present invention, the first heat exchange unit may include a container containing the at least one heat source and the at least one heat pipe, an inlet hole through which the refrigerant enters the container, and an outlet hole through which the refrigerant is emitted from the container. 
     According to another aspect of the present invention, the second heat exchange unit may be formed in such that the heat transfers from the partly vaporized refrigerant to air. 
     According to another aspect of the present invention, the refrigerant may include water (H2O). 
     According to another aspect of the present invention, the cooling system may further include a pump to circulate the refrigerant between the first heat exchange unit and the second heat exchange unit. 
     According to another aspect of the present invention, the at least one heat source may include a battery cell. 
     According to another aspect of the present invention, a battery cooling system is provided. The battery cooling system includes a plurality of plate-shaped battery cells; a plurality of plate-shaped heat pipes alternately disposed between the plurality of battery cells, each including a heat absorbing part and a heat emitting part, wherein a plurality of the heat absorbing parts are in surface contact with the plurality of battery cells so as to absorb heat; a liquid-cooled-type heat exchanger to cool the heat emitting part with a liquid refrigerant; and an air-cooled-type heat exchanger to receive a refrigerant at a first temperature from the liquid-cooled-type heat exchanger, to air-cool the refrigerant to a second temperature lower than the first temperature, and to supply the refrigerant at the second temperature to the liquid-cooled-type heat exchanger. 
     According to another aspect of the present invention, the refrigerant in the liquid-cooled-type heat exchanger may be in direct contact with the heat emitting part. 
     According to another aspect of the present invention, the heat emitting part may be in contact with an external side surface of the liquid-cooled-type heat exchanger in which the refrigerant flows. 
     According to another aspect of the present invention, the plurality of battery cells and the plurality of heat pipes may be soaked in the refrigerant in the liquid-cooled-type heat exchanger. 
     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a diagram of a heated member cooling system according to an embodiment of the present invention; 
         FIG. 2  is a diagram of a portion of a heated member cooling system according to another embodiment of the present invention; 
         FIG. 3  is a diagram of a portion of a heated member cooling system according to another embodiment of the present invention; and 
         FIG. 4  is a diagram of a portion of a heated member cooling system according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
       FIG. 1  is a diagram of a heated member cooling system  100  according to an embodiment of the present invention. The heated member cooling system  100  includes a plurality of heated members  105 , a plurality of heat pipes  110 A, a first heat exchange unit  120 A, and a second heat exchange unit  130 . The heated member cooling system  100  is a system in which a refrigerant circulates through the first heat exchange unit  120 A and the second heat exchange unit  130 ; absorbs heat from the heated members  105  in the first heat exchange unit  120 A in such a manner that the refrigerant, in a liquid state, is partly vaporized; and emits the heat to air in the second heat exchange unit  130  in such a manner that the partly vaporized refrigerant is condensed into a liquid. 
     Each heated member  105  may be a battery cell, a fuel cell, or a semiconductor chip, although the heated members  105  are not limited thereto. For example, the heated members  105  may be battery or fuel cells providing power to an automobile. The heated members  105  are separated from each other. Each of the heated members  105  may be plate shaped and have a flat surface  106 . 
     Each heat pipe  110 A includes, on one side, a heat absorbing part  111 A arranged to contact the heated members  105  to absorb heat from the heated members  105 , and on another side, a heat emitting part  113 A arranged to emit the heat absorbed by the heat absorbing part  111 A and then delivered in the heat emitting part  113 A. 
     The heat pipes  110 A contain a working fluid that is vaporized in the heat absorbing parts  111 A and that is condensed in the heat emitting parts  113 A. The heat pipes  110 A may be, for example, capillary-force type, a gravity type, a centrifugal-force type, an electromagnetic-force type, or the like. Generally, the heat pipes  110 A may be the capillary-force type, although the heat pipes  110 A are not limited thereto. The capillary-force type heat pipes  110 A the include a mesh or groove-shaped capillary structure called a wick. Positioning of the heat absorbing part  111 A is not limited to any particular arrangement or position. 
     The heat pipes  110 A of the gravity type do not include a capillary structure, and thus they are called a wick-less heat pipe or a thermosyphon. In the gravity type heat pipes  110 A, the working fluid condensed in the heat emitting parts  113 A returns to the heat absorbing parts  111 A by gravity. To facilitate this, the heat absorbing parts  111 A are generally formed at a lower position than that of the heat emitting parts  113 A. Table 1 indicates main types of the working fluid according to working temperatures of the heat pipes  110 A. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Working temperature (° C.) 
                 Main types of working fluid 
               
               
                   
               
             
            
               
                 from about −270 to about −70 
                 helium, argon, krypton, nitrogen, 
               
               
                 (very low temperature) 
                 methane 
               
               
                 from about −70 to about 200 
                 water, Freon-based refrigerant, 
               
               
                 (low temperature) 
                 ammonia, acetone 
               
               
                 from about 200 to about 500 
                 naphthalene, sulfur, mercury 
               
               
                 (middle temperature) 
               
               
                 from about 500 to about 1000 
                 cesium, potassium, sodium 
               
               
                 (high temperature) 
               
               
                 equal to or greater than about 1000 
                 lithium, lead, silver 
               
               
                 (very high temperature) 
               
               
                   
               
            
           
         
       
     
     The heat pipes  110 A are interposed between the heated members  105  that are separated from each other. Each of the heat pipes  110 A may be plate shaped and have a flat surface  112  so as to be in surface contact with the flat surfaces  106  of the heated members  105 . 
     The first heat exchange unit  120 A includes a housing  121 , an inlet hole  123  via which a refrigerant is entered to the housing  121 , and an outlet hole  124  via which the refrigerant is emitted from the housing  121 . The refrigerant entering the housing  121  via the inlet hole  123  is in a liquid state and absorbs heat from the heat emitting part  113 A of each heat pipe  110 A. Accordingly, at least a portion of the refrigerant in the liquid state is vaporized and then is emitted via the outlet hole  124 . Since the inlet hole  123  is formed at a lower part of the housing  121  and the outlet hole  124  is formed at an upper part of the housing  121 , the refrigerant flows from the lower part to the upper part in the housing  121  while passing between the heat emitting parts  113 A of the heat pipes  110 A. The refrigerant may be water (H2O). 
     The heat emitting parts  113 A of the heat pipes  110 A are separated from each other. Each heat emitting part  113 A is inserted into the housing  121  so as to directly contact the refrigerant of the first heat exchange unit  120 A. 
     In the second heat exchange unit  130 , the partly vaporized refrigerant, which is emitted from the first heat exchange unit  120 A, emits the heat and then is condensed into a liquid again. The second heat exchange unit  130  may be formed in such a manner that the heat may travel from the partly vaporized refrigerant into air. In the case where the heated member cooling system  100  is applied to an automobile, the refrigerant may be water (or other coolant) to cool an engine, and the second heat exchange unit  130  may be a radiator to condense the water. 
     The second heat exchange unit  130  includes a first tank  131  and a second tank  132  arranged in parallel, a plurality of tubes  137 , and fins  139 . The plurality of tubes  137  extend in parallel to each other while connecting the first tank  131  and the second tank  132 . The fins  139  that promotes heat emission between the tubes  137 . While the refrigerant flows through the tubes  137 , heat from the refrigerant travels to air flowing between the tubes  137 , and then the vaporized refrigerant is condensed into a liquid again. The second heat exchange unit  130  includes an inlet hole  133  through which the refrigerant enters the heat exchange unit  130  (via the outlet hole  124  of the first heat exchange unit  120 A), and an outlet hole  135  through which the condensed refrigerant is emitted from the heat exchange unit  130 . The refrigerant that is emitted from the second heat exchange unit  130  via the outlet hole  135  re-enters the first heat exchange unit  120 A via the inlet hole  123  of the first heat exchange unit  120 A. 
     The refrigerant re-entering the first heat exchange unit  120 A absorbs heat from the heat emitting part  113 A of each heat pipe  110 A, is at least partly vaporized, and then returns to the second heat exchange unit  130 . The heated member cooling system  100  may further include a pump  140  to circulate the refrigerant between the first heat exchange unit  120 A and second heat exchange unit  130 . 
     Table 2 shows a result of measurements of temperature changes across the heated members  105  before operating vs. after operating the heated member cooling system of  FIG. 1  while changing a horizontal length L 1  of the heat emitting part  113 A with respect to the heated member  105 , the heat pipe  110 A, and the first heat exchange unit  120 A of  FIG. 1 . The heated members  105  used for the experiment were battery cells. Water and air were used as refrigerants. A thickness T 1  of the heated members  105  was about 25 mm, and a thickness T 2  of the heat pipe  110 A was about 2.5 mm. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Length of heat 
                 Temperature change at heated member 
                   
               
            
           
           
               
               
               
            
               
                 emitting part (mm) 
                 Air 
                 Water 
               
               
                   
               
            
           
           
               
               
               
            
               
                 10 
                 17.7 
                 2.0 
               
               
                 25 
                 11.5 
                 1.3 
               
               
                 50 
                 7.6 
                 1.5 
               
               
                 75 
                 6.0 
                 1.2 
               
               
                 100 
                 5.4 
                 1.1 
               
               
                   
               
            
           
         
       
     
     As shown in Table 2, it is possible to see that the temperature change at the heated member  105  before operating vs. after operating was relatively little when the refrigerant was water, compared to the experiment in which the refrigerant was air, and that a heat emission effect increases with the length of the horizontal length L 1  of the heat emitting part  113 A, since the temperature change decreases as the horizontal length L 1  increases. 
       FIGS. 2 through 4  are cross-sectional diagrams of heated member cooling systems each including a plurality of heated members, a plurality of heat pipes, and a first heat exchange unit according to various embodiments of the present invention. 
     The heated member cooling system in  FIG. 2  includes a plurality of plate shaped heated members  105 , a plurality of plate shaped heat pipes  110 B interposed between the heated members  105 , and a first heat exchange unit  120 B in which a refrigerant flows. The heated members  105 , the heat pipes  1108 , and the first heat exchange unit  120 B may respectively substitute for the heated members  105 , the heat pipes  110 A, and the first heat exchange unit  120 A in  FIG. 1 . Each heat pipe  110 B includes, on one side, a heat absorbing part  111 B arranged to contact the heated members  105  to absorb heat from the heated members  105 , and on another side, a heat emitting part  113 B arranged to emit the heat absorbed by the heat absorbing parts  111 B. The heat emitting parts  113 B are inserted into the first heat exchange unit  120 B, and thereby directly contact the refrigerant in the first heat exchange unit  1208 . The refrigerant in the first heat exchange unit  120 B may flow in a single direction across the plurality of heat emitting parts  113 B. A horizontal length L 2  of the heat emitting parts  113 B may be less than that of the heat emitting parts  113 A in  FIG. 1 . 
     An experiment was performed to measure temperature changes across the heated members  105  before operating vs. after operating the heat member cooling system of  FIG. 2  while applying one of two different types of refrigerants to the heated members  105 , the heat pipes  110 B, and the first heat exchange unit  120 B. Water and air were employed as the two types of refrigerants. The heated members  105  used for the experiment were battery cells, a thickness T 1  of the heated members  105  was about 25 mm, a thickness T 2  of the heat pipes  110 B were about 2.5 mm, the horizontal length L 2  of the heat emitting parts  1138  was about 1 mm, and a flow passage width W 1  of the first heat exchange units  120 B was about 2 mm. When the refrigerant was air, the temperature change across the heated members  105  before operating vs. after operating the heated member cooling system of  FIG. 2  was about 35° C. When the refrigerant was water, the temperature change across the heated members  105  before operating vs. after operating the heated member cooling system of  FIG. 2  was about 5° C. Thus, it is possible to see that a heat emission effect is highly increased when the refrigerant was water, compared to the experiment in which the refrigerant was air. 
     The heated member cooling system in  FIG. 3  includes a plurality of plate shaped heated members  105 , a plurality of heat pipes  110 C interposed between the heated members  105 , and a first heat exchange unit  120 C through which a refrigerant flows. The heated members  105 , the heat pipes  110 C, and the first heat exchange unit  120 C may respectively also substitute for the heated members  105 , the heat pipes  110 A, and the first heat exchange unit  120 A in  FIG. 1 . Each heat pipe  110 C includes, on one side, a heat absorbing part  111 C arranged to contact the heated members  105  to absorb heat from the heated members  105 , and on another side, a heat emitting part  113 C to emit the heat absorbed by the heat absorbing parts  111 C. Some (but not all) of the heat emitting parts  113 C are bent and extended from the heat absorbing parts  111 C, and a side surface of the bent portions of the heat emitting parts  113 C is in contact with an external side surface of the first heat exchange unit  120 C. The heat emitting parts  113 C are separated from the heated members  105 . The heat travels from the heat emitting parts  113 C to the first heat exchange unit  120 C via a contact surface between the heat emitting parts  113 C and the first heat exchange unit  120 C. A refrigerant in the first heat exchange unit  120 C may flow in a single direction across the plurality of heat emitting parts  113 C. 
     An experiment was performed to measure temperature changes across the heated members  105  before operating vs. after operating the heat member cooling system of  FIG. 3  while applying one of two different types of refrigerants, to the heated members  105 , the heat pipes  110 C, and the first heat exchange unit  120 C. As with the prior experiments, water and air were used as the two types of refrigerants. The heated members  105  used for the experiment were battery cells, a thickness T 1  of the heated members  105  was about 25 mm, a thickness T 2  of the heat pipes  110 B was about 2.5 mm, and a flow passage width W 2  of the first heat exchange unit  120 C was about 2 mm. When the refrigerant was air, the temperature change across the heated members  105  before operating vs. after operating the heated member cooling system of  FIG. 3  was about 50° C. When the refrigerant was water, the temperature change across the heated members  105  before operating vs. after operating the heated member cooling system of  FIG. 3  was about 6° C. Thus, it is possible to see that a heat emission effect is highly increased when the refrigerant was water, compared to the experiment in which the refrigerant was air. 
     The heated member cooling system in  FIG. 4  includes a plurality of plate shaped heated members  105 , a plurality of heat pipes  110 D interposed between the heated members  105 , and a first heat exchange unit  120 D including the heated members  105  and the heat pipes  110 D. The heated members  105 , the heat pipes  110 D, and the first heat exchange unit  120 D may respectively also substitute for the heated members  105 , the heat pipes  110 A, and the first heat exchange unit  120 A in  FIG. 1 . Each heat pipe  110 D includes, on one side, a heat absorbing part  111 D arranged to contact the heated members  105  to absorb heat from the heated members  105 , and on another side, a heat emitting part  113 D arranged to emit the heat absorbed by the heat absorbing parts  111 D. At least some of the heat emitting parts  113 D are bent and extended from the heat absorbing parts  111 D. The heat emitting parts  113 D are not in contact with, but are separated from the heated members  105 . 
     The first heat exchange unit  120 D includes a container  126  including the heated members  105  and the heat pipes  110 D, an inlet hole  127  through which a refrigerant enters the container  126 , and an outlet hole  128  through which the refrigerant is emitted from the container  126 . A refrigerant emitted from the second heat exchange unit  130  of  FIG. 1  enters the first heat exchange unit  120 D via the inlet hole  127 , and the refrigerant that is emitted via the outlet hole  128  may be entered into the second heat exchange unit  130  of  FIG. 1 . The refrigerant in the container  126  may flow from the inlet hole  127  to the outlet hole  128 , may absorb heat from the heat emitting parts  113 D, and may be partly vaporized. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.