Experimental analysis of pump-assisted and capillary-driven dual-evaporators two-phase cooling loop

A mechanical pump-assisted and capillary-driven two-phase cooling loop, with dual-evaporators whose liquid supply lines connected in parallel and series in one loop, was constructed to experimentally investigate the performance of the multi-evaporators cooling loop. In the evaporator, a porous membrane separating liquid and vapor spaces by capillary action is used to promote a thin-film boiling of low thermal resistance. The liquid in a reservoir is first supplied using a mechanical pump to the liquid space in the evaporator and back to the liquid reservoir. Then, a fraction of the liquid in the evaporator is pulled by capillary action through the porous membrane, to porous pin fins and is vaporized on the evaporator heater block where the heat is applied. In this study using the dual-evaporators loop, various heat load conditions were tested using the stepwise heat inputs up to 1200 Watts (102 W/cm(2)), or 600 Watts for each evaporator. Difficulties and limitations experienced with both parallel and series tests are discussed. It is found from the tests that the total heat inputs in the two-phase system govern the system temperatures and pressures, while the individual heat input to each evaporator determines the evaporator temperatures. Setting up the evaporators in parallel allows for more heat load than series. Also, since the evaporators are connected through the vapor and liquid lines, one evaporator can change another evaporator's boiling condition (thermal resistance) even though its heat input is not changed. (C) 2012 Elsevier Ltd. All rights reserved.