Refrigeration cycle

Abstract

A refrigeration cycle provided with a compressor, a condenser, a pressure reduction and expansion means, an evaporator, and an internal heat exchanger for exchanging heat between the refrigerant at the exit side of the condenser and the refrigerant at the exit side of the evaporator, wherein the refrigeration cycle uses R1234yf as the refrigerant and the amount of heat exchange by the internal heat exchanger is greater than or equal to a specific value that has been determined beforehand by a simulation or an experiment. When a currently used refrigerant is changed to a new refrigerant R1234yf, the refrigeration cycle can be operated with a refrigeration ability as same as or greater than that of refrigeration cycles using a conventional refrigerant R134a.

1 . A refrigeration cycle comprising a compressor for compressing refrigerant, a condenser for condensing compressed refrigerant, a pressure reduction and expansion means for reducing in pressure and expanding condensed refrigerant, an evaporator for evaporating pressure-reduced and expanded refrigerant, and an internal heat exchanger for exchanging heat between refrigerant at an exit side of said condenser and refrigerant at an exit side of said evaporator, characterized in that R1234yf is used as refrigerant for said refrigeration cycle, and an amount of heat exchange by said internal heat exchanger is greater than or equal to a specific value that has been determined beforehand by a simulation or an experiment. 
     
     
         2 . The refrigeration cycle according to  claim 1 , wherein said specific value of said amount of heat exchange by said internal heat exchanger is set so that a total refrigeration ability of said refrigeration cycle using R1234yf as refrigerant is greater than or equal to a total refrigeration ability of a refrigeration cycle using R134a as refrigerant under same conditions. 
     
     
         3 . The refrigeration cycle according to  claim 1 , wherein said specific value of said amount of heat exchange by said internal heat exchanger is set as an ability rate to said total refrigeration ability of said refrigeration cycle. 
     
     
         4 . The refrigeration cycle according to  claim 3 , wherein said ability rate of said specific value of said amount of heat exchange by said internal heat exchanger to said total refrigeration ability of said refrigeration cycle is set at 7% or greater. 
     
     
         5 . The refrigeration cycle according to  claim 1 , wherein an opening degree of said pressure reduction and expansion means is controlled depending upon a superheated degree of refrigerant at an exit side of said internal heat exchanger connected to said compressor. 
     
     
         6 . The refrigeration cycle according to  claim 1 , wherein said refrigeration cycle is used in an air conditioning system for vehicles.