The Advanced Injection Low Pilot Ignited Natural Gas Engine: A Combustion Analysis

The Advanced Low Pilot Ignited Natural Gas (ALPING) engine is proposed as an alternative to diesel and conventional dual fuel engines. Experimental results from full load operation at a constant speed of 1700 rev/min are presented in this paper. The potential of the ALPING engine is realized in reduced NO_x emissions (less than 0.2 g/kWh) at all loads accompanied by fuel conversion efficiencies comparable to straight diesel operation. Some problems at advanced injection timings are recognized in high unburned hydrocarbon (HC) emissions (25 g/kWh), poor engine stability reflected by high COV_imep (about 6 percent), and tendency to knock. This paper focuses on the combustion aspects of low pilot ignited natural gas engines with particular emphasis on advanced injection timings (45°–60°BTDC).