Enhance the energy and exergy performance of hydrogen combustion by improving the micro-combustor outlet in thermofluidic systems

摘要

The main reason for the heat loss of micro-combustors is the hot exhaust gases. In this study, the exit part of the conventional micro-combustor has been improved to increase the heat transfer between the hot combustion gases and the walls of the micro-combustor. For this purpose, several approaches have been applied, including porous media, perforated fins, and 24 and 8 tube outlets for outlet replacement. In these improved microcombustors, the thermal performances of the combustion of the hydrogen-air are numerically have been investigated. The results reveal that new micro-combustors by enhancing the velocity of the exhaust gases or increasing the surface area of heat transfer or transferring the hot gases to the walls, has led to a decrease in the temperature of the exhaust gases. However, the wall temperature and its uniformity have increased in the improved micro-combustors. Raising the wall temperature and reducing heat loss have increased radiation efficiency, and reducing entropy generation and energy loss in presented geometries diminish the exergy loss and enhance the exergy efficiency. Also, results showed that micro combustor with porous media has the best energy and exergy performance. Finally, the electrical power generation of micro-combustors has been investigated by photovoltaic cells. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.