Compression Ratio Tuning for Improved Diesel Engine Performance and Emissions Reduction

Abstract

Experiments were conducted on four stroke diesel engine a single cylinder with variable compression ratio (VCR) to evaluate the influence of compression ratio (CR) on performance and emission characteristics when fueled with four types of diesel produced in different refineries in Kurdistan. The tests were carried out at various loads, with a constant speed of 1500 rpm and different values of compression ratio (15, 17, and 18). Engine performance parameters such as brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and emissions of carbon monoxide (CO), carbon dioxide (CO₂), unburned hydrocarbon (HC), nitrogen oxide (NOx), and smoke opacity have been determined for all diesel types. The outcomes indicated that raising the CR produces greater BTE and lower BSFC values. The BTE for diesel fuel types 1, 2, and 4 decreased by 8, 3, and 1%, respectively, in contrast to diesel fuel type 3, however, the BSFC decreased by 7, 26, and 15% in comparison with diesel fuel type 1. The overall combustion process of all diesel fuel, type 3, has resulted in lower emissions of CO, CO₂, HC, NOx, and smoke opacity at all compression ratios, with reductions of 40%, 13%, 71%, and 18%, respectively, when compared to type 1.