Cooling-Induced Depressurization of a Steam-Filled Chamber

Depressurization can be realized by condensing saturated vapor of a pure substance inside a confined chamber. The depressurization rate depends directly upon the effectiveness of cooling to the condensing vapor. The objective of this study is to develop modeling approaches for cooling-controlled depressurization, which will assist the optimization of process design and operation. To this end, an experimental system is set up to provide sets of data for model validations. A simple mechanistic model based on assumption of thermodynamic-equilibrium inside the system has been developed to show the limiting depressurization characteristics with instant heat balance. This simplified model has a merit of quick evaluation on comparisons among various parametric effects. Yet the model is inadequate for real-time quantification in depressurization. The gaps between the measurements and model predictions indicate the importance of local non-uniform heat transfer and condensation. To close the gaps, a complicated full-field computational fluid dynamics modeling and simulation (CFD) is needed, in which the local condensations (especially surface condensation) must be fully account for. The difficulty in CFD approach is the unavailability of condensation-coupled boundary conditions in most commercial CFD codes. Hence, in this paper, we have also proposed the modeling of condensation-based boundary conditions that will be used for CFD simulations.