Numerical studies on the combustion of ultra-low calorific gas in a divergent porous burner with heat recovery. (29th July 2022)

• Record Type: Journal Article
• Authors: Wang, Xiaolong; Deng, Yangbo; Liu, Yang
• Is Part Of: International journal of hydrogen energy. Volume 47:Number 64(2022)
• Page Start: 27703
• Page End: 27715
• Publication Date: 2022-07-29
• Subjects: Divergent porous burner -- Ultra-low calorific gas -- Heat recovery -- Annular channel -- Minimal inlet gas temperature; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2022.06.074
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: This study presents the idea of heat recovery through recirculating walls to enhance the combustion stability for ultra-low calorific gas in a porous burner. Numerical studies on the combustion of ultra-low calorific gas of CO/H2 with CO2 and N2 in a developed divergent porous burner with annular channel is conducted using two-dimensional axis symmetrical model with detailed kinetics. The heat recovery efficiency is defined as the ratio of heat recovery by the fresh mixture in the annular channel to burner power. It is shown that the heat recovery has significant effect on the minimal inlet gas temperature (MIGT) for stable combustion. It is confirmed that the heat recovery enhances the combustion and the stability limits are enlarged by preheating the fresh mixture, but it also leads to an extra pressure loss across the burner compared to that without heat recovery. Results show that heat recovery efficiency reaches up to 0.18 for all the investigated parameters and it reduces linearly from 0.32 to 0.18 as the mass flow ratio increases from 0.8 to 1.5. The MIGT for the burner with heat recirculating channel is always smaller than that without heat recovery. As a result, the combustion is greatly improved by the heat recovery in the divergent burner. Meanwhile, it is shown that pressure loss is increased significantly when the heat recirculating annular channel is added. Highlights: Heat recovery on ultra-low calorific gas in divergent porous burner is conducted with full kinetics. Stability limits are enlarged by heat recovery through preheating fresh mixture. Heat recovery efficiency reaches up to 18% for all the studies parameters. Heat recovery efficiency decreases with the mass flow. The minimal inlet gas temperature is significantly reduced by heat recovery.