| dc.description.abstract | This study applies microporous surface on the two-pass divergent microchannel evaporator to obtain a high performance evaporator for solving high heat dissipation rate electronic devices in near future. The result will be compared with other evaporators, which includes single-pass and two-pass straight microchannel evaporator with microporous surface and single-pass straight microchannel evaporator with plain surface, developed by our lab. The 16 μm average size of aluminum particle is used to make the microporous surface, the average thickness is about 50 μm.
Microporous surface increases the nucleation site density, which enhances nucleate boiling and more bubbles are nucleated. While huge amount of bubble will block the channel easier, which causes the higher pressure drop and performance start decreasing at lower heat flux rate. For two-pass divergent microchannel evaporator, the heat transfer coefficient is increased 16% ~ 54% and the pressure drop is increased 30% ~ 40% when microporous surface is applied.
Comparison in two-pass channel shows that the heat transfer performance of divergent channel is worse than straight one due to the smaller size of first pass channel which will make the blockage of bubble easier. While comparing two-pass channel to single pass one, the latter one shows the better performance because of the shorter channel length.
In practice, apply microporous on single pass straight channel will yield the best performance compared to two-pass divergent and straight channel. Yet, if the inlet and outlet port are constrained to the same side, then two-pass straight channel with microporous surface will be a choice. | en_US |