Effects of Screen Laminates on Droplet Induced Film Hydrodynamics and Surface Heat Transfer

Abstract

Formation of dryout area could lead to a sharp increase in surface temperature during droplet impingement cooling. The objective of this study is to figure out an effective way of suppressing dryout formation in droplet impingement cooling. In this work, HFE7100 droplet train was produced using a piezoelectric droplet generator at a frequency of 6000 Hz with a droplet Weber number of 280. A translucent substrate was coated with a thin film ITO, which was used as a heater in the experiments. A copper screen laminates with a single punched hole (diameter = 3 mm) was placed over the heater surface at a distance of 0.3 mm to enhance surface heat transfer. Optical images showed that screen laminates effectively suppressed the formation of the dryout area. It was also found that heat transfer was greatly improved when screen laminates were used. The heat transfer improvement could be attributed to the enhanced surface tension effects, which keep the whole surface wet at high surface temperatures. In summary, the results show that screen laminates effectively suppress the formation of dryout area and greatly improve surface heat transfer.