Experimental investigations on adiabatic frictional pressure drops of R134a during flow in 5 mm diameter channel

The article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a at a saturation pressure of 5.5 bar corresponding to the saturation temperature of 19.4 degrees C. Study cases have been set for a mass flux varying from 100 to 500 kg/m(2) s. The frictional pressure drop was characterized for the refrigerant R134a, for vapor qualities ranging from 0 to 1. Long-time thermal stability of test facility allowed to gather a comprehensive experimental database for two-phase frictional pressure drop including multiple data points in transition and dryout flow regions. The effect of transition region on the peak value of two-phase frictional pressure drop, for literature models and experiment, is recognized. A systematic assessment of predictive techniques for two-phase frictional pressure drop in adiabatic flows for varying vapor quality was conducted. Both qualitative and quantitative analysis of gathered data vs. literature models was presented. Verification of the pressure drop for two-phase adiabatic flow showed that for Zhang and Webb correlation 93% of experimental data fits in the range of 30%. The model proposed by Thome et al. in other hand predicts almost 33% of data within 10% error, but only 80% of the data is predicted within 30% error. Additional prediction of the peak value of two-phase frictional pressure drop with literature models and the experiment was made. (C) 2016 Elsevier Inc. All rights reserved.