The Research On The Combustion Performances Of The Low Calorific Value Gas Fuel

In our country, Low calorific value gas flue is the most available alternative fuel except of coal, oil and methane. The development and apply of Low calorific value gas flue is very important to ease energy crisis and improve the environment.This paper is a part of project 50676008 supported by National Natural Science Foundation of China. The laminar combustion property and combustion stability of low calorific value gas are analyzed by using the constant volume combustion bomb and engine in this paper.In this paper, the combustion characteristics of low calorific value gas were studied at various equivalence ratios, nitrogen fractions and initial pressures by using the constant volume combustion bomb and Schlieren system. Combustion pressures were measured. Mass burning rate was calculated by using a two zone model and the combustion duration and flame development duration was also analyzed. The flame pictures were recorded by using the high speed camera system, then, the laminar burning velocity and mass burning flux were obtained. The influence of equivalence ratios, nitrogen fractions and diluents fractions on the laminar burning velocity was also analyzed. The results show that with the increase of nitrogen fraction in mixture, the normalized mass burning rate will decrease and the flame development duration and combustion duration will increase at various initial pressures. The fastest normalized mass burning rate and the shortest flame development duration and combustion duration are found at the equivalence ratios near the stoichiometric equivalence ratio. With the increase of initial pressure , the normalized mass burning rate will decrease and the flame development duration and combustion duration will increase at various nitrogen fraction.At last, the symbolic time-series analysis (STSA) was used to analyze the combustion stability of low calorific value gas engine. The results show that with the increase of nitrogen fractions, engine speed and throttle value ,cycle-to-cycle combustion variation will increasing.