Experimental Investigation and Optimization of Exhaust Gas Recirculation on a Euro-1 Variable Speed Compression Ignition Engine

摘要

Automobile emissions are the main source of greenhouse gases (GHG) accumulation in environment. As old engines (Euro III or earlier) produce more emissions and it will be difficult to entirely stop their usage especially in developing and underdeveloped nations, it is desired that appropriate emission reduction technologies are tested on such engines to analyze their feasibility and economical acceptability. While most such studies have been conducted on constant speed stationary engines and modern engines, this study tried to analyze the effectiveness of exhaust gas recirculation (EGR) system on a Euro-1, water-cooled, direct injection, variable speed, compression ignition (C.I.) engine in a laboratory setup in India. This was done by testing an electronic control unit (ECU)-controlled EGR valve running the engine on different speeds; with different torques, as also with varying EGR percentages. Then optimum value of EGR valve opening for each set of engine speed and torque was determined, that is, corresponding to minimum oxides of nitrogen (NO_x). Optimum EGR valve position was programmatically fed, for each set of torque and engine speed (in RPM), into EGR ECU and then the engine was run at varying speeds and torques and the emissions were verified in the automated mode. It was found that using EGR, NOx emissions were substantially reduced (average 45% reduction), without significantly impacting the engine performance. However, smoke emission increased with EGR. In order to counter the adverse effects, additional emission reduction technologies should be used in tandem with EGR.