Ecology, Environment and Conservation Paper

CONTROL EXHAUST EMISSIONS OF INSULATED DIESEL ENGINEFUELLED WITH BIOGAS AND COTTONSEED BIODIESEL

B. Rama Krishna, M.V.S. Murali Krishna and P. Usha Sri

Abstract

Gaseous fuels have many advantages than liquid fuels, as their calorific values of fuels are high, pollutantsemitted by gaseous fuels are low and less dangerous when compared with liquid fuels. The drawbacksassociated with use of vegetable oils in diesel engines such as high viscosity and low volatility can bereduced to some extent by converting them into biodiesel. However, they (biodiesel) cause combustionproblems in diesel engine, due to their moderate viscosity, and hence call for low heat rejection (LHR)engine, which can burn low calorific value fuel, give high heat release rate and faster rate of combustion.The concept of LHR engine is to minimize heat loss to the coolant, thereby increasing thermal efficiency.LHR engine in this investigation consisted of ceramic coated diesel engine. They are many methods toinduct gaseous fuels such as port injection, carburetion technique, injection of gaseous fuel at the near endof compression stroke etc,. Investigations were carried out with biogas gas as primary fuel inducted by portinjection and cottonseed biodiesel was injected into the engine in conventional manner, as India is secondlarge producer of cottonseed oil in the world. Particulate matter (PM), oxides of nitrogen (NOx), carbonmono oxide (CO) levels and un-burnt hydro carbons (UBHC) are the exhaust emissions from a dieselengine. They cause health hazards, once they are inhaled in. They also cause environmental effects likeGreen-house effect and Global Warming. Hence control of these emissions is an immediate effect and anurgent step. The pollutants of PM, NOx,CO and UBHC were determined at full load operation of the enginewith varied injection timing such as recommended injection timing and optimum injection timing. NOxlevels were reduced with provision of exhaust gas recirculation (EGR) at optimum flow rate of 10%. Themaximum induction of biogas with conventional engine (CE) was 35% of total mass of biodiesel as full loadoperation, while it was 45% with LHR engine. Particulate emissions were determined by AVL Smokemeter, while other emissions were measured by Netel Chromatograph multi-gas analyzer at full loadoperation. These pollutants were drastically reduced with induction of biogas and further reduced withadvanced injection timing. NOx levels drastically reduced with EGR.