Investigations on Exhaust Emissions of a Low Heat Rejection Diesel Engine with Alternative Fuels

Abstract

In scenario of fast attenuation of conventional fuels, the search for alternative fuels has become pertinent. Alcohols and vegetable oils are important substitute fuels for diesel, as they are renewable. Vegetable oils have advantages of comparable calorific value and cetane number as that of diesel fuel. Alcohols have merits of high volatility and presence of oxygen in their molecular structure or composition. However, vegetable oils have demerits of high viscosity and low volatility. Alcohols have disadvantages of low cetane number (a measure of combustion quality in diesel engine) and low calorific value. Hence vegetable oils and alcohols call for low heat rejection (LHR) diesel engine, which can eliminate the combustion problems with vegetable oils and alcohols. Investigations were carried out to determine the exhaust emissions from different versions of low heat rejection (LHR) diesel engine such as - LHR-1 engine, (ceramic coated engine), LHR-2 engine (air gap insulated engine) and LHR-3 engine (the combination of LHR-1 and LHR-2 engine) with carbureted butanol and crude jatropha oil (CJO). Hence the advantages of vegetable oil and alcohol can be utilized to reduce pollutants from the engine. Exhaust emissions of particulate matter, oxides of nitrogen (NOx) and aldehydes from different configurations of the LHR engines were determined at full load operation of the engine with test fuels with varied injection pressure and compared with neat diesel operation on conventional engine (CE). Particulate matter and NOx were measured at full load operation by AVL Smoke meter and Netel Chromatograph NOx analyzer respectively. Aldehydes which include formaldehyde and acetaldehyde at full load operation were measured by wet method as dinitrophenyle (DNPH) method. LHR versions of the engine decreased exhaust emissions considerably with carbureted butanol. The emissions decreased further with increase of injection pressure in different versions of the engine.