Design of a liquid bridge heat switch system based on the liquid bridge control for electronics cooling

Abstract

Recently, liquid bridge heat switch has been suggested as effective thermal management solutions for the various thermal problems. The liquid bridge heat switch can control the thermal resistance and the temperature of desired position by regulating the liquid bridge between objective areas. The liquid bridge heat switch system is composed of hot plate as an upper plate, cold plate as a lower plate, and actuators. “On” state demand, the supplied liquid generates liquid bridge between two plates and conducts heat from hot plate to cold plate. The amount of conducting heat and thermal resistance are controlled by the diameter and height of generated liquid bridge. To be an “Off” state, the generated liquid bridge is retrieved and ruptured eventually. At that time, the heat switch system has maximum thermal resistance. This result decreased conduction of heat. In order to realize the desired switch operation, the precise liquid bridge control is required. In this research, the liquid bridge behavior was studied to design the heat switch system. The effects of channel geometry and clearance on the liquid bridge behavior were verified and the liquid bridge rupture conditions were found out. Based on the investigation, the liquid bridge heat switch system was designed for the high power LED cooling system. In a series of experiment, the stable liquid bridge operation was achieved by designed channel geometry. The results also showed that proposed heat switch system was able to decrease the LED junction temperature and regulate the thermal resistance between hot and cold plate.