Pressure Drop in Two-Phase Flow Boiling

The measurements show that the pressure drop in circular and rectangular microchannels depend strongly on the mass and heat fluxes (Tran et al. 2000 Yu et al. 2002 Shuai et al. 2003). 

The flow patterns (expansion of the bubbly, slug and annular regions of flow) affect the local pressure drop, as well as the pressure oscillations in micro-channels (Kandlikar et al. 2001 Wu and Cheng 2003a,b, 2004 Qu and Mudawar 2003 Hetsroni et al. 2005 Lee and Mudawar 2005a). 

The influence of inlet conditions on stability of flow boiling in micro-channels was analyzed by Brutin and Tadrist (2004). The set-up with rectangular micro-channel 500 X 4,000 jm was used to study flow boiling at two kinds of upstream conditions, which corresponded to constant liquid velocity at channel entrance (confinement condition) and constant velocity at the syringe outlet. The flow characteristics corresponding to steady and unsteady regimes were studied and the Reynolds number that subdivided these states was found. 

Hwan and Kim (2006) investigated the pressure drop in circular stainless steel tubes with inner diameter of 244, 430, and 792 pm. These data show that mass flux strongly affects two-phase pressure drop in micro-channels of different diameters. 

In the study by Qu and Mudawar (2003a) experiments were performed to measure pressure drop in two-phase micro-channel heat sink containing 21 parallel 231 X 713 pm micro-channels. The pressure drop in the micro-channel two-phase region APtp was expressed as the sum of acceleration and friction components  

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