Abstract
The concentration dependence of nucleate boiling heat transfer coefficients for HFC-134a and POE oil systems has experimentally been investigated. A horizontal Pt wire (φ 0.1mm) is used for higher ranges of heat flux between 0.02 and 0.3MW・m^<-2>, and a horizontal Nickel-Chromium rod (φ 1.0mm) is used for lower ranges of heat flux of 0.02 MW・m^<-2>. Heat transfer coefficients for HFC-134a/POE systems have been obtained at temperatures of 4 and 9℃ for oil concentrations from 0 to 32 mass%. The present results show that the change in oil-concentration dependence of the heat transfer coefficient due to lower or higher heat flux is not recognized, and the heat transfer coefficient for the systems decreases with increasing oil-concentration as a whole.
