非凝縮性ガスを含む蒸気凝縮器内流れの数値シミュレーション(流体工学,流体機械)  [in Japanese] Numerical Simulation of Flow in Condenser Including Non-Condensable Gas(Fluids Engineering)  [in Japanese]

Condensation heat transfer in condenser is strongly affected by non-condensable gas. To establish the computational model of non-condensable gas bahavior in condenser, numerical simulation of gas/gas two-phase flow (vapor/non-condensable gas) was carried out. In this model, the changes of mass and momentum by condensation were considered and condensation heat transfer coefficient was affected by local density of non-condensable gas. The results obtained from the proposed model showed quantitative agreement in stagnation region and behavior of non-condensable gas. Decreasing rate of mean heat transfer coefficient by non-condensable gas was enlarged with increasing of condensate rate of vapor. Coincidentally, the comparative effect of natural convection in vent tube was enlarged in an exponential manner. It means dischaege of non-condensable gas from condenser is affected by natural convection and forced convection.