3-Dimensional numerical simulation of superadiabatic radiant porous burner with enhanced heat recirculation

摘要

A two-layer porous (fine and coarse) burner consisting of radiation corridors (finned rods) and an external preheater is numerically analyzed. The porous burner holds the flame and heats the finned rods effectively conducting heat to radiating disks downstream, while the sensible energy of the flue gas is recovered before exiting the burner by a preheater carrying a secondary air that mixes upstream with the fuel and primary air. Combination of inherent internal heat recirculation in the porous burner, external heat recovery and effective radiating pathways using the finned rods causes the exiting flue gas having a temperature lower than the radiating disks. The synchronized heat recirculation and preheating extend the lean flammability limit to 0.2 equivalence ratio and allow the radiating disk temperature higher than the exiting flue gas. The thermal nonequilibria (internal heat recirculation, local superadiabatic combustion and external preheating) and effective heat routing using radiation corridors are responsible for this reversed temperature leading to such a record thermal efficiency as high as 50%. (C) 2016 Elsevier Ltd. All rights reserved.