الفهرس | Only 14 pages are availabe for public view |
Abstract This study aims to investigate the effect of the pulsation parameters of the combustion air on the premixed flame behavior and local heat flux inside a vertical water cooled combustor. The combustor is of a cylindrical shape with 6 cm inside diameter and 90 cm length. It is composed of thirty equal cooling jackets. The combustion air is supplied to the combustion unit through a mechanical pulsator which controls the pulsation parameters. Gaseous fuel of 70% Butane and 30% propane was continuously fed to the chamber. The experiments were carried out for both pulsating and steady combustion with a premixed flame at a constant air to fuel mass ratio of 20:1. The pulsation parameters considered in this study. are the frequency and the cycle duty. Three values of the frequency were used 31. 101 and 136 Hz. Also. three cycle duties were applied 25%. 50% and 75%. During each experimental run. the axial temperature distribution along the combustor tube. the local heat flux. the final exhaust carbon monoxide and the flame length were measured.The output results indicated that the combustion process with pulsation has been intensified and the flame length was decreased with a subsequent increase in the heat transfer to the neighbouring cooling jackets. Oscillatory changes in heat flux were observed. Comparison of steady and pulsed combustion operation showed that the unit thermal efficiency increases with pulsed combustion for only certain pulsation otherwise it decreases or slightly be affected. A maximum improvement in the thermal efficiency of about 14% was achieved at a frequency of 136 Hz and a cycle duty of 25%. Exhaust gas analysis showed a decrease in carbon monoxide concentration with increasing both the cycle duty and frequency. It can be concluded that the properly pulsed combustion improves the heat transfer rates and intensifies the combustion. This allows the use of a compact heat exchanger unit for the same thermal capacity. |