A CORRELATION FOR FORCED CONVECTIVE BOILING HEAT-TRANSFER OF PURE REFRIGERANTS IN A HORIZONTAL SMOOTH TUBE

An experimental study is reported on the boiling heat transfer of HFC1 34a, HCFC22, CFC114 and CFC12 flowing inside a 7.9 mm ID horizontal sm ooth tube. Using a water-heated, double-tube type evaporator, the loca l heat transfer coefficients are measured for both counter and paralle l flows. Based on the supposition of Chen that the total heat flux is represented as the sum of forced convective contribution and nucleate boiling contribution, a correlation equation is proposed for the data in the annular-flow regime. The mean deviation between the calculated and measured heat transfer coefficients is 12.2% for the present exper imental data and 9.5% for the data available from literature. The prop osed correlation shows that the nucleate boiling is not fully suppress ed even in the high-quality region in the case of counter flow, while convective evaporation is dominant in the high-quality region with uni form heat flux condition.