EXPERIMENTAL INVESTIGATION ON POOL BOILING OF R600a/MINERAL OIL SOLUTION

摘要

The aim of the present study is an experimental investigation of mineral compressor oil (ISO VG 10) impurity effect on the heat-transfer coefficient during pool boiling of refrigerant R600a. Experiments have been performed for the following parameters: mineral oil mass concentrations in refrigerant were 5%, 10% and 30%; boiling temperatures were -12, -2, 8 and 18℃; heat flow was in the range from 0.5 to 80 kW/m2. The volume of the cylindrical boiler was 1 liter. Stainless steel capillary with 1.6 mm outside diameter and 0.25 mm wall thickness served as a test heater. The length of the test heater was 730 mm. It is shown that the presence of the compressor oil in refrigerant leads to significant reduction in heat-transfer coefficient. The boiling process is highly susceptible to hysteresis at low heat fluxes for gradual increasing of heat loads.