Enhanced pool boiling of propane on horizontal U-shaped tubes in a large-scale confined space

This paper aims to experimentally investigate the heat transfer characteristics of pool boiling on horizontal U-shaped tubes in a large-scale confined space. The saturation temperature ranges from 20 to 40 degrees C and the heat flux varies from 2.5 to 10.5 kWm(-2). Two types of tubes with an outside diameter of 19.05 mm are tested: a smooth tube and a fin-enhanced tube with 0.4 mm fin height, 1220 fpm (fins per meter) and a 0.12 mm fin gap. The tubes are made of titanium with a length of 1165 mm. In case of pool boiling, the heat transfer coefficient for the tested tubes increases with increasing saturation temperature and heat flux. The fin-enhanced tube facilitates the bubble nucleation with the heat transfer coefficient enhancement factor varying in the range of 1.25 similar to 2.28. Furthermore, the experimental heat transfer coefficients are compared with four correlations obtained in the open literature. R-J correlation and Copper correlation are found to be the optimum correlation for the smooth tube and the enhanced tube with the mean relative error of 10.93% and 11.48%, respectively. Findings from this study can supply a fundamental basis for validation and improvement propane heat transfer performances for the intermediate fluid vaporizer (IFV) engineering design.

Automated summary

This paper experimentally investigates the heat transfer characteristics of pool boiling on horizontal U-shaped tubes in a large-scale confined space, finding that the heat transfer coefficient increases with increasing saturation temperature and heat flux for both smooth and fin-enhanced tubes. The fin-enhanced tube facilitates bubble nucleation and enhances the heat transfer coefficient. Comparing experimental heat transfer coefficients with correlations from literature, R-J correlation and Copper correlation are found to be the optimal correlations for smooth and enhanced tubes, respectively.