Experimental Investigations on Lean Burn Spark Ignition Engine Using Methanol - Gasoline Blends

The present study discusses the effects of engine combustion, performance and emission features of methanol-gasoline blend fired lean burn Spark Ignition (SI) engine. Performance features such as Brake Power (BP), Brake Specific Fuel Consumption (BSFC), Brake Thermal Efficiency (BTE), tail pipe emissions namely Hydrocarbon (HC), Carbon Monoxide (CO), Nitrogen Oxide (NO), Carbon di Oxide (CO₂) and combustion characteristics viz. in-cylinder pressure, Heat Release Rate (HRR), Cumulative Heat Release (CHR) and variation of mean effective pressure were measured and compared with that of neat gasoline. Experiments were conducted on a modified sole cylinder four-stroke compression engine (Kirloskar TAF1) to operate as SI engine with a compression ratio of 10.5:1. A new manifold injection system and ignition system were developed by replacing the fuel injection pump and injector. The engine is operated at constant speed of 1500 rpm with different methanol proportions (5%, 10%, and 20%) blended to gasoline under part throttle condition at diverse equivalence ratios. Results revealed that with 5% methanol blend, there was an increase of 3.5% and 5.5% in BP and BTE when compared to gasoline in lean combustion. With 5% blend, HC emissions were reduced by 83%, whereas NO emissions showed a rise. HRR and incylinder pressure were greater for all methanol blends compared to neat gasoline. Overall, 5% methanol blend can be considered the most suitable for lean operation of SI engine.