Effects of design and operating parameters on the performance of a quasi-realistic Diesel cycle engine

Abstract

Although Diesel engines have begun to be abandoned in the automotive industrydue to the emission legislations of the world, they are still widely used ingenerators, work machines, agricultural machines, and heavy vehicles due to theirhigh power density and thermal efficiency. The classical Diesel cycle, which isthe thermodynamic cycle of Diesel engines, was developed by taking into accountirreversibilities, heat transfer losses, friction, and gas exchange process, and aquasi-realistic Diesel cycle was obtained. Also, the working fluid of the Dieselcycle has been accepted as an air-fuel-residual gas mixture instead of air. ThisDiesel cycle model is very useful to examine the effect of Diesel engines' designand operating parameters on engine performance. For this study, the effect ofvariation in equivalence ratio, stroke-bore ratio, and compression ratio on engineperformance was examined. Thermal efficiency, maximum temperature, exhausttemperature, fuel consumption, and specific fuel consumption are used as engineperformance parameters. The characteristics and operating conditions of a Dieselengine in a power generator were used for the numerical study. Engineperformance increased by increasing the equivalence ratio, which is the engineoperating parameter. When the compression ratio, which is the structuralparameter, increased, the engine performance increased, but the maximumtemperature also increased, although it was not desired. Therefore, it is necessaryto optimize the compression ratio and the maximum temperature. Again, when thestroke-bore ratio, which is a structural parameter, was increased, engineperformance decreased, but the maximum temperature decreased as desired. Foroptimization of the two structural parameters, compression ratio, and stroke-boreratio, it is necessary to decrease the stroke-bore ratio while increasing thecompression ratio. The results obtained with the numerical study using the createdmodel are guiding for engine designers.