This study reports a heat flux partitioning during pool boiling in a confined space derived from the flow field and the liquid film structure. The PIV method measured the flow field near a heat transfer surface and the backlighting method clarified the liquid film structure beneath bubbles. The total heat transport was evaluated as the Nusselt numbers of three modes: sensible heat transfer due to microscale convection, latent heat transfer due to liquid film evaporation, and transient conduction due to rewetting. Evaluated Nusselt number of the liquid film increased and that of the microscale convection decreased as the heat flux increased while that of the transient conduction has a peak value at moderate heat flux.
This paper presents Seawater pool nucleate boiling experiments were conducted to examine the difference of the fundamental process of pool nucleate boiling between the seawater and the distilled water. The nucleation site in the seawater experiments was less than that in the distilled water experiment. The decrease of the nucleation site affects inhibit of the boiling and the formation of secondary bubble, and the increase of the superheat of the heat-transfer surface. In the concentrated artificial seawater, the burnout was caused by the increase of the thermal resistance with the increase of the deposition thickness of the sea salt.
Parametric study is conducted for optimizing the thermal performance of loop-thermosiphon for electronic cooling. We have used the Robust design for finding the optimal arrangement of loop-thermosiphon. The result shows the influence factors for temperature of heat transfer surface of heat generating device are cooling temperature, filling rate of working fluid and structure of heat transfer surface. On the other hand, those for thermal resistance are filling rate of working fluid, structure of heat transfer surface and type of working fluid. Result obtained by optimized factors show temperature reduction of heat transfer surface by 13.5K and thermal resistance by 38%. Temperature of heat transfer surface decreases with decrease in cooling temperature and filling rate as well as use of high performance heat transfer surface like pyramid 2.5mm of this study. Thermal resistance also decreases with decrease in filling rate and use of high performance heat transfer surface.