CHF in oscillatory flow boiling channels

Recent advanced technologies in boiler manufacturing bring about highly eff icient and compact water-tube boilers for gas firing or oil firing. These b oilers have very simple water-circulation system, which often brings about flow instabilities followed by critical heat flux, CHF, problems. This pape r describes such an oscillatory flow (CHF) at relatively low mass flux and at low pressure. CHF is a decreasing function of the amplitude and period o f the flow oscillation, and reaches almost 40 % of the steady state value. When the tube wall is thin, CHF is mainly controlled by the two-phase flow dynamics and is well simulated using a simple lumped-parameter model of boi ling channel. At very low mass flux, CHF depends significantly on the how o rientation, and is closely related to the flow pattern transition.