Exergo-Environmental Optimization of a Diesel Engine

Abstract Currently, more than half of the road transport fleet uses diesel engines, which are often identified as the primary source of air pollution. This parameter is enough to optimize engine performance and emissions. The engine optimization can be done using several methods, the most notably by modifying the engine structure, changing the type of fuel using additives and biofuels, or achieving the optimal operating range of the engine. Modifying the engine structure and addition of different kinds of materials to optimize fuel is not recommended either due to necessity of vast time input, financial resources, or extensive research. However, the third way to achieve optimal engine performance conditions can be the most accessible option. According to the results, the best operational load for diesel engine is approx. 94–95% of the full load from the multi-objective optimization point of view, indicating that the optimum load can be achieved before the full load condition. At this point, the operator can achieve the brake power of 198.45 kW and brake thermal efficiency of 40.7% in the presence of brake specific fuel consumption of 0.226 kg·kWh−1. At this condition, CO2 emission is 124.85 g·kWh−1, NOx emission 7.34 g·kWh−1, CO emission 0.6 g·kWh−1, unburnt hydrocarbon emission approx. 0.009 g·kWh−1, and soot formation approx. 0.006 g·kWh−1. This point is equal to the exergy efficiency of approx. 35% and the exergy destruction of approx. 45%. In terms of endpoint results, this condition achieved the impact indices of 7.96E-007 in terms of human health, 0.105 PDF·m2·yr. in terms of ecosystem quality, 0.24 kg CO2 eq. in terms of climate change, and 12.96 MJ in terms of resources.