关键词: 微通道, 两相流, 传热, 界面, 耗散模型, 减阻

Abstract: Microchannel heat exchangers are widely developed in recent years. Heat transfer enhancement and pressure drop reduction are two important goals for designing microchannel heat exchangers. Pin-fin arrays formed porous walls are used as phase separator in flow condensation in microchannels to meet above two challenges. Pressure drop reduction and heat transfer enhancement achieved at the same time. An energy-dissipation based on pressure drop reduction theory was proposed. The reduced two-phase interface area in phase separation flow was the key point to pressure drop reduction. On the other hand, extra liquid was sucked into liquid passage, leaving high-temperature vapor directly contacting pin-fin walls, greatly enhancing condensation heat transfer by deducing film thickness. The diverging liquid channel cross section area ensured liquid being trapped in liquid passage without flooding, accommodating ever increasing liquid along flow direction and ensuring heat transfer enhancement along flow direction. The above phase-separation theory offers new visions for design of condensation heat exchanger in the future.

Key words: microchannels, two-phase flow, heat transfer, interface, dissipation model, pressure drop reduction