Effects of micro-channel geometry and surface modification on heat transfer within an evaporator

A micro capillary pumped loop (MCPL) system is a highly efficient heat transfer device that uses capillary force in the evaporator region as the driving force to pump working fluid in a loop. In this study, the effects of micro-channel geometry and surface modification within an MCPL evaporator of MCPLs will be studied for improving the heat transfer performance. Techniques of surface modification are applied in this study to selectively define the surface as a hydrophilic or hydrophobic area. Results show that the higher the heating power provided by the micro heater, the faster the growing rate of the thermal bubble will be. Generally speaking, the larger the amount of injected working fluids applied, the faster the thermo bubble motion will be. When the size of the channel is scaled down, nucleation of the thermal bubble would occur easily and heat transfer enhancement would be expected. It is also found that bubbles generated by heater h2 (initial location of diffuser) will have a self-driven force to move the bubbles downward because of using a hydrophilic diffuser area. These findings will be useful to the further the optimal design of MCPLs in the future.