Experimental Investigation into the Impact of Natural Gas-Diesel Mixture on Exhaust Emissions and Engine Performance in a Heavy-Duty Diesel Engine with Six Cylinders

Abstract

In this study, experiments were conducted with a mixture of pure diesel and natural gas. In the experiments, a 6-cylinder heavy-duty diesel engine with an engine displacement of 11,670 cc was used and the engine speed was kept constant at 660 rpm. At 660 rpm engine speed, the maximum torque value reached was 386 Nm. The 386 Nm torque value was accepted as 100% and experiments were carried out at torque ratios of 25, 50, 75 and 100%. In all experiments with natural gas mixture, natural gas was delivered to the combustion chamber at a pressure of 1.5 bar and a flow rate of 1.29 g/sec, pre-mixed with air from the intake manifold. The aim of this study is to investigate the combustion characteristics of pure diesel and natural gas mixtures in a heavy-duty diesel engine. According to the test results, the BTE value of natural gas - diesel blended fuel decreased by 157, 89, 53, 53 and 28% at 25, 50, 75, 100 torque values, respectively, compared to pure diesel. It was observed that at low torque values, natural gas - diesel blended fuel was very inefficient, but as the torque value increased, there were improvements in the BTE value of natural gas - diesel blended fuel, although it could not reach the BTE value of pure diesel. In the experiments with pure diesel, it was determined that the fuel consumption was 127, 68, 38, 17% less than the natural gas - diesel blended fuel at torque values of 25, 50, 75, 100%, respectively. The most significant change in exhaust emissions was observed in CO and UHC emissions. At maximum load, CO and UHC emissions were found to be 4.42 and 4.5 g/kWh for pure diesel and 19.9 and 11.9 g/kWh for natural gas blend, respectively.