Two-phase flow maldistribution in minichannel heat-sinks under non-uniform heating

In the present study, two-phase heat transfer characteristics in minichannel heat sinks under non-uniform heating were experimentally investigated. Pin–fin and strip-fin minichannel heat sinks were fabricated on a thin brass plate such that the channel dimensions were 25 mm wide × 26 mm long × 1 mm deep. 2 mm × 5 mm spot-heater was attached on the backside of the minichannel heat-sinks to simulate the non-uniform heating. The surface temperature distribution caused by the non-uniform heating was measured using the thermocouples attached on the 9 uniformly spaced locations of the minichannel heat-sinks. It was observed that the two dimensional expansion of vapor in the pin–fin minichannel heat-sink allowed improved distribution of vapor and thereby lower vapor quality. The temperature rises at the hot-spot locations was also significantly lower in the pin–fin minichannel heat-sink, which means pin–fin structure is more suitable for hot-spot cooling. The effects of mass flow rate and heat flux on heat transfer capability were explored and the total thermal resistances of the heat-sinks were also evaluated and discussed.