Experimental study on convective boiling heat transfer for pure refrigerants and refrigerant mixtures in a horizontal tube

Title & Authors
Experimental study on convective boiling heat transfer for pure refrigerants and refrigerant mixtures in a horizontal tube
Sin, Ji-Yeong; Kim, Min-Su;

Abstract
Boiling heat transfer coefficients of pure refrigerants (R22, R32, R134a, R125, R290, and R600a) and refrigerant mixtures (R32/Rl34a, R290/ R600a, and R32/R125) are measured experimentally and compared with Chen's correlation. The test section is a seamless stainless steel tube with inner diameter of 7.7mm and uniformly heated by applying electric current directly to the tube. Heat fluxes range from 10 to 30kW$\small{^2}$. Mass fluxes are set to 424 ~ 742kg/m$\small{^{2}}$s for R22, R32, R134a, R32/R134a, and R32/Rl25 ; 265 ~ 583kg/m$\small{^{2}}$s for R290, R600a, and R290/R600a. Heat transfer coefficients depend strongly on heat flux at a low quality region and become independent as quality increases. Convective boiling term in the Chen's correlation predicts experimental data of the pure refrigerants fairly well (relative error of 12.1% for the data of quality over 0.2). The correlation for pure substances overpredicts the heat transfer coefficients for nonazeotropic refrigerant mixtures.
Keywords
Refrigerant Mixtures;Convective Boiling;Nucleate Boiling;Heat Transfer Coefficient;
Language
Korean
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