Vapor-compression type refrigerating machine and heat exchanger therefor

Abstract

An oil repellent film 31 a is formed on an inner wall of the tube 31. By the formation of the oil repellent film 31 a , it becomes possible to prevent refrigerating machine oil remaining in the evaporator 30. Therefore, a sufficiently large quantity of refrigerating machine oil can be returned to the compressor, and the occurrence of seizing of the compressor can be prevented. As it is possible to prevent refrigerating machine oil remaining in the evaporator 30, while a reduction in the coefficient of heat transfer between refrigerant and the tube is being prevented, it is possible to prevent a substantial sectional area of the refrigerant path of the tube 31 from decreasing. Therefore, an increase in the pressure loss in the evaporator 30 can be prevented. Accordingly, the heat absorbing property of the evaporator 30 can be enhanced.

1 . A heat exchanger applied to a vapor-compression type refrigerating machine, an oil repellent film having an oil repelling property being formed on an inner wall face of a tube composing a refrigerant path.  
     
     
         2 . A heat exchanger applied to an evaporator, which is one of the heat exchangers provided in a vapor-compression type refrigerating machine and exhibits a refrigerating capacity by evaporating refrigerant, an oil repellent film having an oil repelling property being formed on an inner wall face of a tube composing a refrigerant path.  
     
     
         3 . A heat exchanger according to  claim 1 , wherein surface tension of material composing the oil repellent film is lower than that of refrigerating machine oil mixed with refrigerant.  
     
     
         4 . A heat exchanger according to  claim 1 , wherein material composing the oil repellent film is silicon resin or fluororesin.  
     
     
         5 . A vapor-compression type refrigerating machine using an ejector, comprising; 
 a compressor for sucking and compressing refrigerant;    a radiator for cooling refrigerant discharged from the compressor;    an evaporator for evaporating refrigerant so as to absorb heat, composed of a heat exchanger described in  claim 1;     a nozzle for converting pressure energy of refrigerant of high pressure, which has flowed out from the radiator, into velocity energy by expanding refrigerant in a reduced pressure;    an ejector including a boosting section for boosting the pressure of refrigerant by converting velocity energy into pressure energy when refrigerant of gas phase evaporated in the evaporator is sucked by a flow of refrigerant of high velocity injected from the nozzle and then refrigerant injected by the nozzle and refrigerant sucked from the evaporator are mixed with each other so as to convert velocity energy into pressure energy; and    a gas-liquid separator for separating refrigerant into gas-phase refrigerant and liquid-phase refrigerant and supplying the liquid-phase refrigerant to the evaporator and also supplying gas-phase refrigerant to the compressor.