Effects of inlet pressure on wall temperature and exergy efficiency of the micro-cylindrical combustor with a step

Energy conversion efficiency of a micro thermophotovoltaic (TPV) system strongly depends on wall temperature of micro combustors and its uniformity. In this work, a 3D numerical model is built to investigate effects of inlet pressure on premixed H2/air combustion in a micro-cylindrical combustor with a step. The variation of velocity, temperature and specific entropy field are analyzed. Moreover, in order to characterize the uniformity of wall temperature, a nonuniformity coefficient RT,w is introduced. Results suggest that the variation of velocity, temperature and specific entropy field is mainly existed at the reaction and outlet regions. And the highest mean wall temperature (1265.59K) is arrived at pin=0MPa, while the lowest nonuniformity coefficient RT,w (5.06) and the highest exergy efficiency (40.29%) is approached at pin=0.1MPa. In the viewpoint of energy usage, the micro combustion system has the best performance at pin=0.1MPa due to that it has the potentiality to obtain better energy conversion efficiency and higher exergy efficiency. This work provides us a direction to improve the performance of the micro combustor without changing the structure of the micro combustor, and can combine with other optimization methods.

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