Comparative Study on the Performance and Emission of a Bi-Fuel Compressed Natural Gas (CNG) Engine

Abstract

This paper presents experimental data of the effects of performance and emission using gasoline and compressed natural gas (CNG) as fuel on a multi cylinder spark ignition (SI) engine. The engine used in this experiment is Mitsubishi engine 4G91 model, 1.5L. The study was concentrated on engine performance parameters such as brake specific fuel consumption (bsfc), brake power (BP), b ) and brake mean effective bth pressure (bmep) while exhaust emissions gas such as carbon monoxide (CO), hydro carbon (HC) and nitrogen oxide (NOx) were being measured. The performance tests were conducted on Chassis Dynamometer with engine running at varies speed and engine rpm ranging from 1000 rpm up to 4500rpm. The exhaust gas emissions were measured by using an exhaust gas analyzer. The collected data was analyzed to assess the overall performance of the engine at several engine speeds. The experiment is performed the comparison of the engine performance and emission between engine that using different type of fuel; either with gasoline or with CNG. It shows that CNG can reduce up to 50% to 80% of the overall emission compared to gasoline engine. However, the engine performance reduces approximately 10% to 20%. Generally, it was expected that the performance will be reduced accordingly due to the engine being designed is not applicable specifically for CNG application.