Experimental study of exhaust emissions and performance of a dual fuel IDI diesel engine

Abstract

Dual fuel engines of the compression ignition type provide an alternative approach for I.C. engines to improve economy, reduce exhaust emissions and achieve a greater power. The present contribution is an experimental investigation to evaluate such a statement using a modified Ricardo E6 indirect injection diesel engine. Methane and, sometime, propane were used as the gaseous fuel while regular diesel fuel was used as the pilot one. The admission of more gaseous fuel with the intake air increased the engine power, thermal efficiency, and NOx emissions while CO and UHC emissions increased up to the flame initiation limit beyond which they decreased sharply. The experimental results showed higher engine powers and efficiencies, lower CO and UHC emissions, and unfortunately higher NOx emissions and narrower knock-free operating range with employing larger pilot fuel quantifies, advancing the pilot fuel injection timing, and increasing the intake temperature. Preliminary results of EGR, on the other hand, showed improvements in all engine parameters for EGR ratio up to 50%. In order to achieve better performance, the present results suggest increasing the pilot fuel quantity, the injection-timing advance, and the intake temperature at light loads and the opposite at high loads. This is in addition to the use of EGR for the entire load range.