抄録
The effect of unequal heating load applied to each pass (reffered to as "step heating load" in this paper) on two-phase flow distribution in multipass evaporator was experimentally studied. Four step heating patterns were determined to take into account the flowrate and the flow direction of the air flows outside of the evaporator tube in the actual heat exchanger. Three total heat input conditions were taken as Q = 300,450,600 W. For each heating condition, header inlet quality was varied from 0.07 to 0.3. From the exeperimental result of flow distribution, it was found that step heating load obviously affect the flow distribution. Step heating load causes the difference among the pressure at the inlet of each pass, which affect the liquid division ratio at the junction. But this effect does not clearly appear when the momentum flux of fluid in the main pipe just before the junction is large. It is concluded that liquid phase flow is directed by the kinetic condition in the vicinity of each junction. Together with the results obtained at the authors' first report, the empirical correlation for estimating the liquid division ratio at each junction which was successfully applied to any condition of heating load was derived. Additionally, from the result of pressure drop measurement, it was found that the vapor phase flow distribution had strong relation to the profile of the pressure drop along each pass.
