Flow Boiling Heat Transfer Characteristics of Water in a Capillary Tube under Sub-atmospheric Pressure Condition

摘要

Flow boiling heat transfer characteristics of water in a vertical capillary tube, ID=1.45mm, is experimentally investigated for a range of pressure from 10 to 50 kPa, mass flux from 17 to 100 kg/m{sup}2s and heat flux from 25 to 900 kW/m{sup}2. Based on the adiabatic flow pattern maps, the dominant flow pattern is found to be slug-annular and annular flow. Two different heat transfer trends are observed with respect to local quality. At quality less than 0.05, the heat transfer coefficient increases sharply, but the coefficient is almost constant at a quality higher than 0.05. Katto's correlation well predicts the present CHF values.