Heat transfer and pressure drop characteristics of ammonia/miscible oil mixture during flow boiling in an 8 mm horizontal smooth tube

Abstract

The flow boiling characteristics of ammonia/miscible oil mixture are experimentally studied. Experiments are conducted in an 8 mm tube at oil concentration from 0 to 5.78%, mass flux from 51 to 99.5 kg m−2 s−1, heat fluxes of 9 and 21 kW m−2, and temperature from −5.5 to −5 °C. The heat transfer is basically deteriorated with the influence of miscible oil. Specifically, the effect of miscible oil is small in low vapor quality region, and with a rise in vapor quality, the oil causes significant heat transfer deterioration at smaller mass flux. Meanwhile, Gungor and Winterton (1986) correlation can predict 98.5% of the experimental data within ±30% error band. In addition, the experimental results reveal that the pressure drop are insensitive to the oil concentration.