In this study, superheating and sub-cooling heat exchangers in vapor-compressed refrigeration system are analyzed from thermodynamics and economical (refrigeration system operation cost, investment cost) viewpoints. Using four different refrigerants (R22, R502, R134a and R404a), the temperature of condenser at the interval of (35-55 degrees C) and temperature of evaporator at the interval of (-10 to 10 degrees C) have been obtained from the calculation process. The second law analysis (analysis of irreversibility) of a refrigeration system is carried out and then the whole system is optimized thermo-economically. As a result of calculations, optimum superheating and sub-cooling temperatures of heat exchanger (superheating, sub-cooling) areas corresponding to these temperatures are obtained. Copyright (C) 2007 John Wiley & Sons, Ltd.