Experimental study on the effect of coal to liquid on combustion and emission of heavy-duty diesel engine with exhaust gas recirculation

The work aims not only to exploit the petroleum alternative fuel for relieving the energy crisis, but also to realize the ultra-low emissions of diesel engines fueled with this alternative fuel. The effects of direct coal liquefaction (DCL) on combustion and emissions have been studied in a heavy-duty engine fueled with exhaust gas recirculation (EGR). Two cases of the diesel engine operating condition were studied: 1000 r/min, 110 N m (referred to as Case A) and 1400 r/min, 473 N m (referred to as Case B). The experimental results showed that with the increase of EGR, the maximum in-cylinder pressure, rate of heat release and mean gas temperature decrease; the brake fuel conversion efficiency (BFCE) first increases slightly then decreases; brake specific fuel consumption (BSFC) has the opposite variation trend to BFCE. As the increase of EGR, the nitrogen oxides (NOx) emissions decrease monotonically, the soot emissions increase slightly, the hydrocarbon (HC) and carbon monoxide (CO) emissions increase, and the carbon dioxide (CO2) and oxygen (O2) concentration of the exhaust products increases and decreases respectively. The trade-off relationship between NOx and soot emissions can be improved when diesel engines are fueled with DCL instead of diesel.