Entropy generation of hydrogen flow in a curved annular duct

Abstract

The main objective of this study is to numerically investigate the entropy generation of both hydrodynamically and thermally fully developed laminar flow of hydrogen gas under various operating pressures and temperatures in the concentric curved annular ducts with rectangular cross section. In this regard, the solutions of discretized continuity, momentum and energy equations have been obtained using elliptic Fortran Program based on the SIMPLE algorithm. The solutions have been achieved for (1) Dean numbers ranging from 2.3 to 202.9, (2) Annulus dimension ratios of 5.5, (3) Operating pressures of 0.101325, 1, 10, 40, 70 and 100 MPa, (4) Core wall temperature of 50 and 80 ºC, (5) Duct wall temperature of 25 ºC. In this regard, overall entropy generation in the whole flow field has been analyzed in detail. Moreover, the effects of Dean number, operating pressure and core wall temperature on entropy generation arising from the flow and heat transfer have been investigated. Accordingly, it is concluded that the effect of volumetric entropy generation that is a result of fluid flow can be neglected as compared with volumetric entropy generation due to heat transfer. When Dean number, operating pressure and core wall temperature increase the total volumetric entropy generation goes up. Thus, it is expected that this study will contribute to develop the energy efficient-hydrogen gas heaters for practical applications including hydrogen exchangers, PEMFC applications, hydrogen gas turbines, chemical mixing processes and hydrogen gas dryers in hydrogen industry.