EVAPORATIVE HEAT TRANSFER IN HORIZONTAL TUBES WITH STREP-TYPE INSERTS USING REFRIGERANT-600A

Results of a study on saturated boiling heat transfer of refrigerant R-600a in horizontal tubes (ID=10.6 mm) with strip-type inserts (longitudinal strip LS and cross-strip CS Inserts) are reported. Local heat transfer coefficients are measured for a range of heat flux (3.86~90 kW/m²), mass velocity (82.3~603.3 kg/ m²s), and equilibrium mass quality (≤0.8) and the influences were studied. The data were compared with the performance of the corresponding smooth tubes. Enhancement performance ratios are also presented and discussed. Finally, correlations were developed for the evaporation heat transfer coefficients and friction factors for horizontal tubes with strip-type inserts with/without holes using R-600a.