Boiling in a horizontal three dimensional microfin tube for R134a

In-tube boiling: experimental results for RI34a are presented in a new horizontal three-dimensional (3-D) microfin tube. The purpose of this work is to test its boiling heat transfer performance.:The experimental data are taken at two different boiling pressures, 0.54 and 0.65 MPa, respectively. The mass flux is between 100 and 277 kg/m(2). s and the heat flux is 10 and 20 kW/m(2). The effects of mass flux, vapor quality, treat flux and boiling pressure on the heat transfer coefficient are reported. The results of the new 3-D inner microfin tube are also compared with the data of smooth tube, which are calculated by Wattelet's correlation. The average enhancement ratio is between 1.5 to 2.1 in the test region.