Ammonia-air combustion and explosion characteristics at elevated temperature and elevated pressure

Abstract

Experimental and numerical study on ammonia-air combustion and explosion characteristics at elevated temperature and pressure was conducted. The results revealed that the ammonia-air flame of different equivalence ratios is quite smooth at elevated temperature and pressure. The laminar burning velocity (LBV) reaches the peak of 0.073 m/s at Ф = 1.1 and increases as increasing initial premix temperature and decreasing initial premix pressure. Maximum explosion overpressure (MEO) and maximum pressure rise rate (MPRR) reach the peak of 0.43 MPa and 0.13 MPa/ms respectively at Ф = 1.1. The theoretical MEO is significantly higher than the experimental results due to heat loss, and the minimum heat loss occurs at Ф = 1.1. MEO, MPRR and heat loss increase with increasing initial premix pressure, and MEO and heat loss decrease with increasing initial premix temperature, while MPRR increases. Okafor mechanism has the best LBV prediction performance among seven mechanisms. And the main elementary reactions affecting LBV are H + O2=O + OH and HNO + HH2+NO.