Heat Transfer Characteristics of Water During Flow Boiling in a Vertical Rectangular Mini-channel

Flow boiling heat transfer of water in a vertical rectangular mini-channel is investigated experimentally in this study. Heat transfer coefficient data are obtained for a mass flux range of 5∼58 kg/m2s and a heat flux range of 1∼5.6 kW/m2. The influence of heat flux, mass flux and vapor quality on heat transfer coefficient is also analyzed. The heat transfer coefficient increases with increasing heat flux but is mostly independent of mass flux and vapor quality. Based on the existing three-zone model, a new theoretical model is established to calculate the heat transfer coefficient of confined bubbly flow region. With the Mean Absolute Error being 9.72%, the new model provides a good prediction to the experimental results.