PERFORMANCE AND EMISSIONS ANALYSIS OF CNG–DIESEL DUAL FUEL ON A VCR ENGINE

Abstract

The rapidly depletion of petroleum reserves or resources have promoted research for alternative fuels for internal combustion engines. The C.I. Engine is a very important prime mover being used in the buses, trucks, locomotives, tractors, pumping sets and many other applications, small and medium electric power generation and marine propulsion etc. The running costs of C.I. Engines are much less than S.I. Engines and hence make them attractive for industrial, transport and other applications. A dual fuel diesel engine is a diesel engine fitted with a fuel conversion kit to enable use of clean burning alternative fuel like compressed natural gas. Dual fuel engines have number of potential advantages like fuel flexibility, lower emissions, higher compression ratio, better efficiency and easy conversion of existing diesel engines without major hardware modifications. In view of energy depletion and environmental pollution, dual fuel technology has caught attention of researchers. It is ecological and efficient combustion technology. The objective of the present major project work is to investigate the possibility of dual fuelling of Compression Ignition (C.I.) engine with Diesel and Biodiesel with Compressed Natural Gas (CNG) in order to reduce engine emissions and enhance its thermal efficiency. A Direct Ignition, single cylinder 4 stroke 3.5kW Variable Compression Ratio Diesel Engine was operated in dual fuel mode. The engine was initially started with Diesel injection and subsequently CNG was supplied with the incoming air. After self-ignition of diesel and blend of biodiesel fuel, CNG-Air mixture ignited The investigation on three different compressions ratio show the use of CNG resulted in significant reduction of smoke opacity and Nitrogen oxide (NOX) emissions with a slight penalty on CO and HC exhaust Emissions. Our study also throws light on present limitations and drawbacks of dual fuel-engines and proposed methods to overcome these drawbacks. Analysis of recent research activities carried out to study effect of different parameters affecting performance of diesel - CNG and Biodiesel - CNG dual fuel engines is also summarized here. Future scope of research for these engines is also discussed.