Experimental Study on Flow Boiling Characteristics in Continuous and Segmented Microchannels with Vapor Venting Membrane

Flow boiling in microchannels is one of the promising techniques for heat dissipation occurred in micro devices. However, the rapid bubble growth must be suppressed, which leads to serious boiling instabilities, high pressure drop, and low heat transfer coefficient. The addition of porous hydrophobic membrane has proven an effective method to remove the vapor in-site in the literature. However, the effects of heat sink’s topological structures on the vapor venting are still a research gap. The present study experimentally investigates the influence of Polytetrafluoroethylene (PTFE) membrane on fluid flow pattern, pressure drop, vapor venting performance, and heat transfer characteristics of flow boiling in the continuous and segmented heat sinks. Results show that the vapor venting membrane can reduce the pressure drop and increase the heat transfer coefficient effectively by decreasing the exit vapor quality, especially in combination with the segmented structures. The interconnection area as a space for bubble growth and coalescence is beneficial for vapor venting due to increased vapor pressure and quantity. Following the enhanced vapor discharge, the fluctuation of pressure drop is further weakened, which is conducive for the safe operation of heat sink.