Syngas/Diesel Dual Fuel Combustion in a Compression Ignition Engine with Different Composition Ratios of Syngas and Compression Ratios

합성가스/디젤 혼소압축착화 엔진의 합성가스 혼합비와 압축비에 따른 연소 및 배출가스 특성

Abstract

Syngas is widely produced by incomplete combustion of coal, water vapor, and air (oxygen) in a high-temperature/high-pressure gasifier through a coal-gasification process for power generation. In this study, a simulation syngas which was mainly composed of $H_2$, CO, $CO_2$, and $N_2$ was fueled with diesel. A modified single cylinder compression ignition (CI) engine is equipped with intake port syngas supply system and mechanical diesel direct injection system for dual fuel combustion. Combustion and emission characteristics of the engine were investigated by applying various syngas composition ratios and compression ratios. Diesel fuel injection timing was optimized to increase indicated thermal efficiency (ITE) at the engine speed 1,800 rpm and part load net indicated mean effective pressure ($IMEP_{net}$) 2 to 5 bar. ITE of the engine increased with the $H_2$ concentration, compression ratio and engine load. With 45% of $H_2$ concentration, compression ratio 17.1 and $IMEP_{net}$ 5 bar, ITE of 41.5% was achieved, which is equivalent to that of only diesel fuel operation.

Fig. 1 Schematic diagram of experimental engine setup

Table 4 Piston design specification

Fig. 2 ITE of syngas and diesel depending on diesel injection timing at IMEP_net 3 bar

Fig. 3 ITE of syngas and diesel depending on diesel injection timing at IMEP_net 5 bar

Fig. 4 Coefficient of variation in IMEP_net

Fig. 5 Lambda of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 6 Indicated thermal efficiency of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 7 Pumping mean effective pressure of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 8 Ignition delay and main combustion duration of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 9 Indicated specific hydrocarbon of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 10 Indicated specific carbon monoxide of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 11 Indicated specific nitrogen oxides of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 12 Smoke opacity of syngas and diesel at IMEP_net 2 to 5 bar

Fig. 13 Substitution rate at IMEP_net 2 to 5 bar

Table 1 Experimental engine specification

Table 2 AC Dynamometer specification

Table 3 Composition ratios of simulation syngas