Theoretical and numerical analyses of a ceramic monolith heat exchanger

Abstract

This study assessed the performance of a ceramic monolith heat exchanger, estimating heat transfer and pressure drop by numerical computation and the e-NTU method. A heat exchanger consists of rectangular ducts for exhaust gas, a ceramic core, and rectangular ducts for air and exhaust gases, as well as air in the cross-flow direction. The numerical computations were performed for the whole domain, including the exhaust gas, ceramic core, and air. In addition, the heat exchanger was examined using a conventional e-NTU method with several Nusselt number correlations from the literature to characterize the flow in the rectangular duct. The results of these numerical computation analyses demonstrated that the effectiveness of the heat exchanger, as demonstrated using the e-NTU method with Stephan’s Nusselt number correlation, came closest to the results of computation with a relative error of 2%. The air-side pressure drops indicated by the results of numerical computation were 13–22% higher than those calculated using the head loss equation with the inclusion of a friction factor that was obtained from previous experiments examining heat transfer conditions.