Author : D. Srikanth, M.V.S. Murali Krishna and P. Usha Sri

Vegetable oils and alcohols are important substitutes for diesel fuel, as they are renewable in nature. However, drawbacks associated with vegetable oils (high viscosity and low volatility) and alcohols (low cetane number and energy content) pose restrictions to use in diesel engines. Biodiesels derived from vegetable oils present a very promising alternative for diesel fuel, since they have numerous advantages compared to fossil fuels. They are renewable, biodegradable, provide energy security and foreign exchange savings besides addressing environmental concerns and socio–economic issues. However drawbacks associated with biodiesel of high viscosity and low volatility which cause combustion problems in CI engines, call for engine with hot combustion chamber. They have significant characteristics of higher operating temperature, maximum heat release, and ability to handle low calorific value fuel. Investigations were carried out to evaluate the performance with low heat rejection combustion chamber with crude cotton seed biodiesel. It consisted of an air gap insulated piston, an air gap insulated liner and ceramic coated cylinder head with different operating conditions of cotton seed biodiesel with varied injection timing. The optimum injection timing with conventional engine (CE) was 31o bTDC (before top dead centre), while it was 28o bTDC for engine with LHR combustion chamber with biodiesel. Comparative studies were made for engine with LHR combustion chamber and CE at manufacturer’s recommended injection timing (27o bTDC) and optimum injection timing with biodiesel operation. Engine with LHR combustion chamber with biodiesel showed improved performance at 27o bTDC and at optimum injection timing over CE. Preheated biodiesel showed improved performance and combustion characteristics over normal biodiesel.

Keywords: Vegetable oil, Biodiesel; LHR combustion chamber; Fuel performance; Combustion characteristics

Article published in International Journal of Current Engineering and Technology, Vol.6, No.2 (April-2016)