Modeling and thermodynamic cycle analysis of condensation-induced depressurization

Abstract

A condensation-induced depressurization and steam purging technology has been recently developed to drive a continuous gas flow at a sub-atmospheric pressure. The technology is based on a continuous regeneration of depressurization by a system of two or multiple alternatively-operated chambers with steam condensation and refilling. Comparing with traditional methods, this new vacuum generation technology has a great potential of high energy conversion and utilization for an open-flow system. A complete operation cycle of each chamber undergoes three stages in sequence: vacuum generation by condensing pre-refilled steam, vacuuming gas from application system, and purging gas out of chamber while refilling steam. This paper presents a mechanistic model of process characteristics and parametric analysis for the thermodynamic cyclic operations. Each process stage has been separately modelled, and the complete cycle characteristics are then integrated by connecting these stages in series. The mechanistic model provides a parametric analysis capability for the optimized operation of the developed technology to vacuum driving continuous gas flows at sub-atmospheric pressures. The model result is compared with experiment data with good match. The parametric study of the steam purging process indicates that increasing the steam flowrate and pre-heating of chamber can effectively reduce the purging time required by 20–40%.