Abstract
The present study describes the experimental investigations carried out to study the influence of modified piston bowl geometry at a constant speed of the combustion, performance and emission characteristics of a direct injection compression ignition diesel engine. The modified piston profiles, namely hemispherical combustion chamber (HCC) and toroidal combustion chamber (TCC), are manufactured with a baseline compression ratio of 17:1, and the effects of compression ratio (16:1, 17:1 and 18:1) are analyzed. Experiments are carried out with pure diesel for low load to full load conditions for better understanding. With an increasing compression ratio of the engine, TCC piston geometry has shown better improvement in brake thermal efficiency, carbon monoxide and hydrocarbon emissions than HCC. However, a slight penalty in NOx emission is observed with increasing compression ratio and TCC piston geometry. In-cylinder peak pressure, net heat release rate and rate of pressure rise are increased significantly with increasing compression ratio and the use of TCC geometry.
Highlights
The annual energy outlook revealed that the total energy consumption for transportation sector was 38% and global liquid fuel consumption was 68% in the year 2018 and if it continues in the same way, the usage of the liquid fuel for transportation sector may rise up to 72% in 2035 [1]
Abbreviations used for the discussion are hemispherical combustion chamber without exhaust gas recirculation (EGR): base-HCC; toroidal combustion chamber without EGR: base-TCC; hemispherical combustion chamber with 10% EGR: EGR–HCC; and toroidal combustion chamber with 10% EGR: EGR–TCC
Maximum brake thermal efficiency (BTE) achieved with base-TCC was 33.12%, which was higher by 5.67% than base-HCC
Summary
The annual energy outlook revealed that the total energy consumption for transportation sector was 38% and global liquid fuel consumption was 68% in the year 2018 and if it continues in the same way, the usage of the liquid fuel for transportation sector may rise up to 72% in 2035 [1]. It has a major drawback, higher HC and CO emissions and uncontrolled combustion when fueled with high cetane rating fuel like diesel [5]. Little modification on naturally aspirated CI engine may make it possible to commercialize HCCI technology In this context, design of combustion chamber (CC) plays a vital role in achieving better performance and emissions characteristics of direct injection CI engines. Jaichandar et al [13] investigated the effect of toroidal reentrant combustion chamber (TRCC) and hemispherical combustion chamber (HCC) on brake thermal efficiency (BTE) and emission characteristics of a single cylinder direct injection CI engine.
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