Calculation and experimental verification of heat transfer coefficient for low pressure methanol evaporator.

Natural refrigerants are attracting attention due to their environmental neutrality. They have good thermal properties, but their evaporation pressures at near room temperatures are just a few kPa. There is limited information regarding evaporation of methanol at low-pressures. Empirical correlations for boiling heat transfer coefficient that were developed at atmospheric pressure levels tend to give high errors. In this paper we show an experimental data for pool boiling of methanol in pressure region 0.3–18 kPa and heat fluxes 10–45 kW/m2. The results are compared to calculations based on eight empirical heat transfer coefficient correlations. Since all of them yielded noticable errors, we suggested new constants for the power law equation that allow more accurate prediction of heat transfer coefficient.