Thermodynamics performance analysis of flue gas treatment process using ceramic membranes

Abstract

Transport membrane condenser is a device for recovering water and heat from flue gas. Porous nature of ceramic membrane makes properties of water vapor condensation and fluid flow different from those in traditional heat exchangers. Therefore, irreversible losses caused by heat transfer and flow resistance of transport membrane condenser is also unique and worthy of studying. This paper uses entransy and entropy analysis methods to calculate irreversible losses of transport membrane condenser, and analyzes effects of fluid temperature on entransy dissipation and entropy generation rates. With the goal of reducing irreversible losses, operation mode and structure size of transport membrane condenser are optimized under designed conditions. Based on specific application cases, this paper finds that entropy analysis method has a certain limitations when studying irreversible losses of transport membrane condenser. The limitation is embodied in the analysis of heat transfer problems under the condition that fluid temperature changes significantly. Furthermore, an optimization method suitable for engineering design is proposed. According to theoretical results, flue gas inlet temperature is preferably in the temperature range of 52 °C–55 °C; under the condition that water balance of power plant is not destroyed, increasing flowrate of cooling water as much as possible.