Experimental study on bubble departure diameter of ethane saturated nucleate poolboiling

Nucleate pool boiling in ethane was studied at 0.15, 0.2 and 0.3 MPa at heat flux between 14.27and 81.22 kW•m^-2by visualization technique. Images of departure ethane bubbles at uppersmooth surface of the vertical 20 mm-diameterheating copper rod were recorded at a frame rate of 2619 fps and a full resolution of 960×720 pixels by Phantom high-speed digital camera. The departure bubble diameters were gotby image processing and analyzed relationship with Jacob number(Ja). With the increase in Ja, bubble departure diameter tended to increase but not monotonically. Compared experimental diameter data with predictions of six most used correlations, it was found that Kim andKim(2006) model had the best prediction with absolute average deviation (AAD) below 30% at all three pressures and 50% of the predicted values within 30%-40% deviations at 0.15 MPa. Finally, a new correlation was proposed on a basis of fitting bubble departure data and Kim and Kim (2006) power law model, which has within ±30% difference between prediction and experimental data. The prediction for methane departure diameters at four different pressures were within ±30% (only one over ±30%) of the literature data. The new correlation works well for both methane and ethane at various operating conditions, however, its application range is limited because the correlation is obtained from data under low Ja.