Performance of bioethanol and diesel fuel by thermodynamic simulation of the miller cycle in the diesel engine

Abstract

The rapid growth in automotive industry and increased fuel consumption and environmental pollution, along with decrease in oil and fossil fuel resources, necessitate the adoption of new technologies to improve engine thermal efficiency and the use of alternative fuels. So, the present study proposes the thermodynamic cycle model of engine based on the Miller cycle and the use of bioethanol and diesel fuels. To analyze the cycle performance after examining the thermodynamic processes of the Miller cycle in the pressure diagram in terms of volume and calculating the amount of the operating fluid (fuel) and its thermodynamic properties based on bioethanol and diesel fuels and a homogeneous mixture of air, temperature was determined at the key points of engine operation through thermodynamic relationships. Then, the changes of engine performance parameters including output power and thermal efficiency were compared in terms of compression ratio based on Miller cycle using bioethanol and diesel fuels and they were also compared to the Otto cycle. The results showed that by increasing density ratio, the output power and thermal efficiency first increase and then decrease. Assuming to have the same volumetric efficiency and use bioethanol fuel, the engine output power and thermal efficiency would increase. Under optimum conditions of engine performance, power at the maximum point of efficiency and efficiency at the maximum point of power in the Miller cycle were greater than those of the Otto cycle. The results can be generalized to Atkinson cycle and other alternative fuels and used in a more practical way in the design and performance evaluation of internal combustion engines.

Keywords

• Engine
• Bioethanol
• Performance
• Compression ratio
• Thermal efficiency
• Output power