Development of a modified mass transfer model based on height function method to capture the pressure oscillation occurred in direct contact condensation process

Abstract

For direct contact condensation (DCC) simulation, it is a challenge to capture the numerical characteristic of pressure oscillation precisely, especially the frequency and amplitude. It is the most crucial key issue to calculate the mass transfer across the vapor-liquid interface. Up to now, the pressure characteristic is generally obtained by experiment and the existing mass transfer models always lead to unacceptable deviation from the experiment result. In order to estimate the accurate pressure characteristic, a modified mass transfer model is originally proposed based on the height function method in this paper. An estimation method for the interfacial area density in this model is derived from the algebraic spherical model with the mean bubble diameter. This method correlates the interfacial area concentration with the measurable interfacial curvature and the interfacial curvature is calculated by the height function method. The proposed model is then employed based on the VOF method for the verification of Stefan's analytical problem and steam bubble condensation problem. The corresponding numerical results are both in great agreement with the analytical and experimental results. In addition, the proposed model achieves its advantage for the steam flow condensation to obtain more accurate results of pressure oscillation than other mass transfer models. The numerical result of pressure oscillation frequency is 8.9 Hz, close to the experimental data of 10 Hz with a deviation of 11%. However, the energy balance model and Lee model predict that the frequencies are 31.5 Hz and 19 Hz relatively with the corresponding deviation of 215% and 90%. It is validated to be convincing with excellent accuracy and shows promise for extensive numerical simulation for direct contact condensation applications.