Ignition and Combustion Characteristics of Gas-to-Liquid Fuels for Different Ambient Pressures

Abstract

Gas-to-liquid (GTL) fuel exhibits potential as a clean alternative diesel fuel, suitable for addressing problems of energy security and environmental pollution. The main objective of this research was to provide fundamental data for the ignition and combustion of GTL fuels. Experiments were conducted in a constantvolume combustion vessel to investigate the effects of ambient temperature on ignition delay and combustion characteristics for various ambient pressures. Three kinds of GTL fuels with different distillation properties and their blends in gas-oil (conventional diesel fuel) were tested. The experimental results showed that all tested fuels exhibited similar ignition-delay trends: ignition delay increased as ambient temperature and ambient pressure decreased. The variation of ignition-delay values was small at temperatures higher than 700 K but large at temperatures less than 700 K. In addition, the results showed that the ignition-delay trends of GTL fuels depended significantly on distillation properties. GTL fuels with high cetane number corresponded to shorter ignition delay and smoother heat-release rate than those for gas-oil at the same temperature and pressure. Particularly, their good ignitabilities at low temperature might make it feasible to premixed-charge compression-ignition (PCCI) operations. In addition, the shadowgraph images showed that GTL fuels evaporated and mixed with the hot air quicker than gas-oil. Moreover, the blend GTL fuel helped improve ignition and combustion compared to gas-oil. The obtained results contribute to find the optimal condition of design and operation in diesel engines fuelled by GTL fuels.

Effects of Inlet Pressure on Ignition of Spray Combustion

“…Therefore, the influence of inlet pressure on the atomization quality of the nozzle and combustion chemical reaction rate is the main reason for the difference in the ignition process in the combustion chamber. The effect of ambient pressure on the atomization of pressure-swirl atomizer was discovered long ago by relevant [15][16][17][18][19][20] when the ambient pressure is higher than the standard atmospheric pressure (P a = 0.1-0.4 MPa), the SMD at the exit of the pressureswirl atomizer increased with ambient pressure, and the spray cone angle gradually decreased. The relationship between SMD and ambient pressure and that between SMD and air density can be expressed as SMD≈P a 0.27 and SMD≈ρ a 0.126 , respectively.…”

“…The ambient pressure has been mostly affected on ignition such as fuel atomization [15][16][17][18][19][20], minimum ignition energy [21][22][23][24], flame kernel propagation speed [25], and burning velocity [26]. The aero engine generally operates under a negative pressure at a high altitude, and the ignition performance is related to engine safety and reliability.…”

Ignition and combustion characteristics of various biodiesel fuels (BDFs)

“…The emission of diesel engine related with combustion processes of BDF has been described to have lower emissions of smoke, particulate matter (PM), carbon monoxide (CO) and hydrocarbon (HC) as compared using diesel oil, while the engine performance is almost unchanged or improved [14][15][16][17]. The targets of numerous researchers are extensively using BDFs to reduce CO 2 emission and the pollutant emissions to the environment and also to overcome the problem of NO x emission [2][3][4][5][6][7][8][9][10][13][14][15][16][17][18]. However, very few researches have the fundamental data of ignition and combustion characteristics of BDF which are strongly affected by the properties of fuel.…”

“…The results showed that the potential of shorter ignition delay and lower heat-release rate is obtained by using higher cetane number and lower volatile fuels. The higher cetane number fuels generally depicted the shorter ignition delay and better fuel-air mixing [18]. Biodiesel intends to give better ignition quality though it has slightly lower cetane number than diesel oil.…”

Application of Biodiesel in Automotive Diesel Engines

“…Several publications have reported that GTL with lower density has a shorter penetration delay. However, these were based on the global fuel spray characteristics using a relatively low speed camera [21,13]. The temporal resolution is not high enough to capture the near-field spray process.…”