Heat Transfer Performance Prediction of Confined Thin Film Boiling

Abstract

The liquid-vapor phase change is considered as one of the most effective way to transfer heat flux. Improving the heat transfer efficiency and critical heat flux (CHF) is crucial to face our energy-intensive and energy-deficient plight. Pool boiling in a confined thin liquid film is known to have the ability improve the heat transfer efficiency. This work theoretically predicted the heat transfer performance of the confined thin film boiling using non-vapor permeable gap through the thermal resistance analysis. The model showed the same trend as the practical situation that the thermal resistance can be reduced by the reducing the liquid thickness but the vapor leaving resistance was increased at the same time. The heat transfer efficiency can be increased by the decrement of both the liquid layer conduction resistance and convection resistance at the bubble interface because of the smaller bubble size and higher efficiency inside the confined thin liquid layer with higher temperature. But both the CHF and efficiency will be influenced a lot by the vapor leaving resistance from the gap. This work demonstrated the influence of superheat, gap size and gap length, also showed the potential to further increase the heat transfer efficiency and CHF if the vapor leaving resistance can be further reduced when using the vapor-permeable gap.