Investigations on Low Heat Rejection Diesel Engine With Carbureted Alcohols and Crude Cotton Seed Oil

Abstract

Alcohols and vegetable oils are promising fuels for replacing conventional diesel fuel. The advantages of alcohol (more volatility, low carbon to hydrogen ratio) and vegetable oils (comparable calorific value and cetane number) are attracting features to use them as substituted fuels in diesel engines. However demerits of alcohol (low calorific value and low cetane number (measure of combustion quality in diesel engines)) and vegetable oils (high viscosity and low volatility) call for low heat rejection (LHR) engine which has high heat release rate and faster rate of combustion. Heat flow to the coolant is minimized by providing thermal insulation in the path of heat flow to the coolant. Investigations were carried out to study the exhaust emissions from high grade low heat rejection (LHR) diesel engine consisting of air gap insulated piston with 3-mm air gap with superni (an alloy of nickel) crown, air gap insulated liner with superni insert and ceramic coated cylinder head with normal temperature condition of crude cottonseed oil and carbureted alcohol (methanol/butanol) with varied injection pressure and compared with methanol operation over butanol operation and also with net diesel operation on conventional engine (CE). Exhaust emissions of particulate matter and oxides of nitrogen (NOx) were recorded by AVL Smoke meter and Netel Chromatograph NOx analyzer respectively at full load operation of the engine. Aldehydes were measured by dinitrophenyl hydrazine (DNPH) method at full load operation of the engine. Particulate levels and NOx levels decreased by 92% and 12% respectively with LHR engine at recommended injection timing of 27 o bTDC (before top dead centre) and at an injection pressure of 190 bar with methanol operation in comparison with neat diesel operation on CE.