Development of an exhaust gas recirculation strategy for an acetylene-fuelled homogeneous charge compression ignition engine

2010 ◽  
Vol 224 (7) ◽  
pp. 941-952 ◽  
Author(s):  
K Sudheesh ◽  
J M Mallikarjuna
Keyword(s):  
Thermal Efficiency ◽  
Homogeneous Charge Compression Ignition ◽  
Exhaust Gas Recirculation ◽  
Electrical Heating ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Brake Thermal Efficiency ◽  
Load Limit ◽  
Gas Recirculation ◽  
Load Conditions

This paper deals with experimental investigations carried out to develop an exhaust gas recirculation (EGR) strategy for an acetylene-fuelled homogeneous charge compression ignition (HCCI) engine. This study involves an analysis of the external inlet charge heating, the use of a mix of hot EGR and cool EGR to extend the load range, and the performance of the engine in the acetylene HCCI mode. First, experiments are conducted on a single-cylinder engine in the acetylene HCCI mode with external electrical heating at different load conditions, and the best inlet charge temperatures at each load condition are obtained. Second, hot EGR or a mix of hot EGR and cool EGR (i.e. the EGR strategy) is used to reduce or eliminate external charge heating and to extend the upper load limit, or to improve the brake thermal efficiency. In both cases, the engine performance is compared with that of the conventional diesel compression ignition (CI) mode. It is found that with EGR, above 25 per cent of load, the upper load limit at different inlet charge temperatures increases by about 16 28 per cent without any external charge heating. Below 25 per cent of load, the electrical heating at different inlet charge conditions is reduced by about 67–87 per cent. The brake thermal efficiency increases by 5–24 per cent under all the load conditions and it is comparable with that in the conventional CI mode. In the HCCI mode, nitrogen oxide levels are less than 20ppm. Smoke levels are always lower than 0.1 Bosch smoke unit. Hydrocarbon and carbon monoxide emissions are relatively higher than for the conventional CI mode.

The impact of water injection and exhaust gas recirculation on combustion and emissions in a heavy-duty compression ignition engine operated on diesel and gasoline

2019 ◽  
Vol 21 (8) ◽  
pp. 1555-1573 ◽  
Author(s):  
Michael Pamminger ◽  
Buyu Wang ◽  
Carrie M Hall ◽  
Ryan Vojtech ◽  
Thomas Wallner
Keyword(s):  
Thermal Efficiency ◽  
Water Injection ◽  
Combustion Process ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Brake Thermal Efficiency ◽  
Fuel Ratio ◽  
Main Injection ◽  
Gas Recirculation ◽  
Diesel Operation

Steady-state experiments were conducted on a 12.4L, six-cylinder heavy-duty engine to investigate the influence of port-injected water and dilution via exhaust gas recirculation (EGR) on combustion and emissions for diesel and gasoline operation. Adding a diluent to the combustion process reduces peak combustion temperatures and can reduce the reactivity of the charge, thereby increasing the ignition-delay and, allowing for more time to premix air and fuel. Experiments spanned water/fuel mass ratios up to 140mass% and exhaust gas recirculation ratios up to 20vol% for gasoline and diesel operation with different injection strategies. Diluting the combustion process with either water or EGR resulted in a significant reduction in nitrogen oxide emissions along with a reduction in brake thermal efficiency. The sensitivity of brake thermal efficiency to water and EGR varied among the fuels and injection strategies investigated. An efficiency breakdown revealed that water injection considerably reduced the wall heat transfer; however, a substantial increase in exhaust enthalpy offset the reduction in wall heat transfer and led to a reduction in brake thermal efficiency. Regular diesel operation with main and post injection exhibited a brake thermal efficiency of 45.8% and a 0.3% reduction at a water/fuel ratio of 120%. The engine operation with gasoline, early pilot, and main injection strategy showed a brake thermal efficiency of 45.0% at 0% water/fuel ratio, and a 1.2% decrease in brake thermal efficiency for a water/fuel ratio of 140%. Using EGR as a diluent reduced the brake thermal efficiency by 0.3% for diesel operation, comparing ratios of 0% and 20% EGR. However, a higher impact on brake thermal efficiency was seen for gasoline operation with early pilot and main injection strategy, with a reduction of about 0.8% comparing 0% and 20% EGR. Dilution by means of EGR exhibited a reduction in nitrogen oxide emissions up to 15 g/kWh; water injection showed only up to 10 g/kWh reduction for the EGR rates and water/fuel ratio investigated.

Exhaust gas recirculation stratification to control diesel homogeneous charge compression ignition combustion

2012 ◽  
Vol 13 (5) ◽  
pp. 429-447 ◽  
Author(s):  
Mathieu André ◽  
Bruno Walter ◽  
Gilles Bruneaux ◽  
Fabrice Foucher ◽  
Christine Mounaïm–Rousselle
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Experimental Studies ◽  
Exhaust Gas Recirculation ◽  
Combustion Noise ◽  
Control Technique ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Compression Ignition Combustion ◽  
Gas Recirculation ◽  
Homogeneous Charge

A single-cylinder diesel engine was used to investigate the potential of exhaust gas recirculation dilution stratification as a control technique for homogeneous charge compression ignition combustion with early direct injections. Experimental studies on both all-metal and optically accessible engines were performed to understand the processes involved when exhaust gas recirculation is introduced separately in the intake ports. Laser-induced fluorescence diagnostics were carried out in the optical engine in order to provide fuel and exhaust gas recirculation distributions. The results indicate that depending on the intake configuration, the exhaust gas recirculation stratification can be maintained until late timings corresponding to the combustion event, leading to decreased maxima of heat-release rates, as well as decreased combustion noise levels. This result suggests that exhaust gas recirculation stratification may be used as a control parameter for combustion speed and therefore may contribute to the extension of the homogeneous charge compression ignition operating range. However, although exhaust gas recirculation stratification appears to be an interesting new control technique for homogeneous charge compression ignition combustion, its effect on the combustion was shown to be very sensitive to parameters such as the intake system configuration or the exhaust gas recirculation composition, showing that industrial use of this control technique requires further understanding of the physical phenomena involved.

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