Derivations of Correlation and Liquid-Solid Contact Model of Transition Boiling Heat Transfer

抄録

The correlation of liquid-solid contact fraction in transition boiling was derived by focusing on the dimensionless wall temperature θ=(T_w-T_CHF)/(T_MHF-T_CHF). The following correlation was obtained from experimental results for water, R-113 and LN₂: Γ=1.000-0.9120θ-0.1343θ², where q_tb=q_CHFΓ+q_MHF(1-Γ). In the present model, considering a pseudo-liquid solid contact right after the detachment of a bubble from a liquid-vapor interface, transient heat conduction was analyzed in it three-dimensionally. Liquid-solid contact time and area were determined by the present correlation of the fractions of liquid-solid contact: τ_contact=0.3Γ_t, A_wet=15 × 15 × Γ_a, Γ_t=Γ_a=Γ^0.5={1.000-0.9120θ-0.1343θ²}^0.5. The heat transfer during the wet period was estimated using q_wet=f(ΔT_sat^0.8). The prediction by the present model was in agreement with the present experimental data for water. Furthermore, a simulation of the rewetting was performed; the experimental results of cooling curves during the rewetting were well reproduced by the transient heat conduction model using the present correlation of transition boiling heat transfer and the present liquid-solid contact model.