Effects of in-cylinder catalytic coating on the performance of a two-stroke spark ignition engine

Two-stroke spark ignited engines offer superior power to weight ratio, which is best suited for two-wheeler applications. But, low thermal efficiency and higher emission levels are the main drawbacks of these engines. In-cylinder catalytic coating was applied in a two-stroke single cylinder spark ignited engine for improving thermal efficiency and reducing emission levels. The selected catalyst (copper), which is an oxidation catalyst, was coated over the inside surface of cylinder head and piston crown by plasma coating method. Detailed studies were carried out to evaluate the performance of catalyst under varied operating conditions. The copper coated engine showed improved fuel economy at all operating conditions. The brake thermal efficiency was improved by 10% and the unburned hydrocarbon emission was reduced by 25% at full load condition of the engine. The plasma coating of catalyst showed no deterioration after 50 h of operation and the catalytic action was not affected. Detailed combustion analysis was carried out to find out the effect of catalyst action on combustion parameters. It was found that the rate of burning, P-max, and heat release rate were increased. Combustion duration was reduced by 8 degrees of crank angle at full load condition.