Pressure drop during condensation of refrigerant R134a inside horizontal tubes

The author introduces and analyses the two-phase pressure drop correlation for refrigerant R134a in the condenser of a heat pump heating-cooling system. The following correlation will be included: the Lockhart and Martinelli, Friedel, Chrishom, Tran et al, Wang et al. and the Wilson et al. The previously mentioned correlations were analyzed numerically depending on mass velocity and vapor quality. The aim of the analysis is to choose the optimum model from the tested ones. The applied method of analysis is numeric-graphic.