Characteristic study on boiling heat transfer of R417A and R22 outside smooth and enhanced tubes

Abstract

This paper presents information about boiling heat transfer of R417A replacing R22 outside horizontal smooth and enhanced tubes at the saturation temperature of 10°C. A Wilson plot technique was used to determine the refrigerant heat transfer coefficient. The results indicate that boiling heat transfer coefficients of R22 are larger than those of R417A at the same condition of saturation temperature and heat flux. Boiling heat transfer coefficient of R22 of tube E30 is 1.79 times as R417A, while 1.46 times as R417A for smooth tube. Boiling heat transfer coefficients of enhanced tube are larger than those of smooth tube at the same condition of saturation temperature and heat flux. Boiling heat transfer coefficient of enhanced tube E30 is 2.61 times as smooth tube for R22 at the condition of heat flux(75 kW m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ). For R417A, tube E30 is 2.23 times as smooth tube at the condition of heat flux(60 kW m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ).