variavel0=<b>Enio Pedone Bandarra Filho</b> - bandarra@sc.usp.br Laboratório de Refrigeração - EESC - USP
<b>José Maria Saiz Jabardo</b> - mjabardo@sc.usp.br Laboratório de Refrigeração - EESC - USP
<b>Abstract.</b> Present research deals with an experimental study of the heat transfer of refrigerant R-134a undergoing convective boiling inside horizontal smooth and microfin tubes. An experimental apparatus has been developed and constructed whose main component is a horizontal tube electrically heated with 9.52mm external diameter. Tests have been performed preferentially at the inlet test section temperature of 5ºC, heat flux of 5 and 10 kW/m2, mass velocity 100, 200 and 300 kg/s.m2 and average quality between 5 e 90%. Experimental results showed that the heat transfer coefficient can increase about 400% for microfin tube in comparison to smooth tube. The average enhanced factor was 5 to G=100 kg/s.m2, 2 to G=200 kg/s.m2 and 1.3 to G=300 kg/s.m2.
<b>Keywords.</b> Enhancement, Convective boiling, R-134a, Microfin, Refrigerant.