Friction Factor and Pressure Drop Oscillations during Flow Boiling of Water in a Vertical Micro Channel

Experiments on flow boiling of water are carried out for a rectangular vertical channel with dimension (width × depth) 0.86×2.0 mm2 (hydraulic diameter dh=1.2 mm). The Confinement number Co* for the investigated range of operating parameters is about 2.2. So, applying the criterion Co*>0.5 for micro channels, the investigated channel has to be classified as "micro". Investigations of heat transfer and pressure drop were carried out for different mass and heat fluxes. Results of pressure drop for single and two-phase flow are presented. On the basis of experiments a single-phase friction factor is obtained. Moreover, the two-phase frictional pressure drop was undertaken. For both cases comparisons with available correlations are presented. Preliminary results of pressure drop oscillation analyses are shown. The paper contains recent experimental results of an ongoing EU-project. Previous results have been presented in Shuai etal. [1], [2].