Experimental study of bubble behaviors during boiling of a hydrocarbon refrigerant

The present work emphasizes the experimental observation of bubble behaviors in pool boiling of a pure (hydrocarbon, HC) refrigerant on coated surfaces. A refrigerant R-600a was used as one of HC refrigerants in this study. The coated surface was prepared by using a thermal spraying method where copper powder was coated over the copper substrate surface having an inside diameter of 16.6 mm and 201 mm length. The bubble behaviors during the saturated boiling of refrigerant were captured by a high-speed camera and characterized as number of nucleation sites, diameter of departing bubbles, and departure frequency. The boiling augment depends on the surface characterization, which affects the bubble dynamics during boiling processes. The number of nucleation sites and diameter of departing bubbles vary as an increase of applied heat flux. The departure frequency of bubble reduces as heat flux increases. The present outcomes compared with the experimental data of refrigerant R-134a to demonstrate the reason behind the current results. Data of this study were correlated in the form of non-dimensional terms and differentiated with the available predicted correlations.