An investigation of drop impingement on a heated surface

• Main Author: Lim, Wei Liat
• Other Authors: Wong Teck Neng
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68470
• Institution: Nanyang Technological University

Spray cooling is a relatively unknown heat transfer method steadily gaining interest and popularity especially for high heat flux applications. This method shows great promise and high potential with reported heat flux reaching 1200 W/cm2, developing into the preferred cooling method for most high heat flux thermal cooling applications. In this study, experiments were conducted on a high power multi-nozzle closed loop spray cooling set-up to investigate the effects of large enhanced surfaces on spray cooling heat flux performance. A copper block was machined with extended pin fins of dimensions 0.5 mm x 0.5 mm x 1 mm to achieve a heating surface area of dimensions 23.3 cm x 16.0 cm. Refrigerant R-134a was selected as the working fluid for spray cooling, and the heat transfer performance for both plain and enhanced surfaces were calculated and compared. The findings indicate that surface enhancements improve the heat transfer performance in large area spray cooling similarly to smaller-scale studies. Chamber pressure considerably determined the mean surface temperature and average heat transfer coefficient. Surface enhancements yielded an average mean surface temperature decrease of 7.3 °С with an accompanying increase in average heat transfer coefficient of 1.8 W/cm2∙K as chamber pressure increases. The large enhanced surface heater block yielded remarkably improved heat transfer performance over the plain surface equivalent.