with the collaboration of Iranian Society of Mechanical Engineers (ISME)

Document Type : Research Article


Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran


Today, maximizing the efficiency of fuels and increasing the output power of diesel engines is considered inevitable due to the increasing need for energy resources, the reduction of fossil fuel resources, the need to maintain the environment, reduce air pollution, and limit the electricity supply and fuel supply. In the large cities of Iran, the problem of vehicle pollution is one of the main problems. The lack of proper fuel, soot filters, and absence of requirement for a technical inspection of diesel vehicles have led to an increase in mortality and the growth of lung cancer due to pollution. All of studies indicate that fossil fuels, despite the low cost of production, will increase the cost of both living and environment. A solution for this crisis is to reduce the sources of pollutant-producing sources from the source of these pollutants. In the internal combustion engines, the compression ratio and alternative fuels are two important factors affecting engine performance and exhaust emission.
Materials and Methods
In this research, a one-dimensional computational fluid dynamics solution with GT-Power software was used to simulate a six-cylinder diesel engine to study the performance and exhaust emissions with different compression ratios and alternative fuels. The compression ratio was chosen to be 15:1 to 19:1 with an interval at unity. Alternative fuels such as (as base diesel), methanol, ethanol, diesel and ethanol, biodiesel and decane were selected. To modeling engine, first, all parts of the engine were introduced as a real six-cylinder engine, and then the required data were entered according to the actual engine conditions at the atmospheric pressure of one atmosphere. Before this investigation was carried out, a validation model for evaluation was done by experimental and simulation data. The validation results showed that software model error is acceptable and the model has a good capability of fitting and predicting.
Results and Discussion
The engine performance was evaluated in terms of engine power, engine torque, and specific fuel consumption at different engine compression ratio and fuel. The results showed that with increasing the compression ratio, brake power and brake torque increased. Among the fuels used in this engine, the maximum brake power and brake torque in the compression ratio of 19 with the decane fuel were 3.86% higher than that the base fuel and the lowest value was awarded in the compression ratio of 15, with methanol fuel and it was equal with 56.04%. The results indicated that by increasing compression ratio, the brake specific fuel consumption was reduced due to more power than the fuel consumed in the engine. A fuel with lower heating value should be injected more mass to the engine. This will increase the brake specific fuel consumption. In this research, the decane fuel with a compression ratio of 19 with a reduction of 3.72% had the lowest brake specific fuel consumption among other fuels. The CO emission from the engine largely depended on the fuel's properties, the availability of oxygen, the fuel mix with air, temperature, and turbulence inside the combustion chamber. The results highlighted that by increasing compression ratio, CO emission increased and CO emission in biodiesel fuel, with a compression ratio of 15, was decreased by 82.37% compared to the base. CO2 emissions are not too harmful to humans, but they increase the potential for ozone depletion and global warming. With increasing compression ratio, CO2 and HC emissions increased for all fuels, CO2 emissions have risen up the base. The fuel heating mechanism, combustion temperature, oxygen content, and gas fuel availability are the most important factors in the formation of NOx. With increasing the compression ratio, the amount of NOX increases, which is due to the high temperature in the cylinder at a higher compression ratio. The viscosity and density of fuels have an effect on NOX emission, and because of the larger droplets of the fuel, it released NOX. The highest NOx emissions from biodiesel fuel are due to the high oxygen content of this fuel and the lowest NOx emissions from decane fuel, due to the low density of the fuel compared to other fuels.
The results of this study showed that the decane fuel with a compression ratio of 19 in total had the best functional and pollutant characteristics among the six fuel used in this study. Therefore, this fuel can be the best alternative for diesel fuel.


Open Access

©2021 The author(s). This article is licensed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source.

Aldhaidhawi, M., R. Chiriac, V. Bădescu, H. Pop, V. Apostol, A. Dobrovicescu, M. Prisecaru, A. Alfaryjat, M. Ghilvacs, and A. Alexandru. 2016. Performance and emission of generator Diesel engine using methyl esters of palm oil and diesel blends at different compression ratio. Pages 012135. IOP Conference Series: Materials Science and Engineering: IOP Publishing.
2. Arul Mozhi Selvan, V., R. Anand, and M. Udayakumar. 2009. Combustion characteristics of Diesohol using biodiesel as an additive in a direct injection compression ignition engine under various compression ratios. Energy and Fuels 23: 5413-5422.
3. Atefi, A., S. A. Hosseini, and S. Kamgar. 2011. Investigating the effect of compression ratio changes on four-stroke diesel engine performance. in First National Conference on Agricultural Mechanization and New Technologies. Ahvaz, Iran. (In Farsi).
4. Bavafa, M., M. Tabasizade, A. Farzad, B. Ghobadian and H. Eshghi. 2016. Effect of poultry fat oil biodiesel on tractor engine performance. Journal of Agricultural Machinery 6 (1): 14-24. (In Farsi).
5. Bora, B. J., and U. K. Saha. 2016. Experimental evaluation of a rice bran biodiesel–biogas run dual fuel diesel engine at varying compression ratios. Renewable Energy 87: 782-790.
6. Dubey, P., and R. Gupta. 2018. Influences of dual bio-fuel (Jatropha biodiesel and turpentine oil) on single cylinder variable compression ratio diesel engine. Renewable Energy 115: 1294-1302.
7. Eaton, D. A. 2014. PyRAD: assembly of de novo RADseq loci for phylogenetic analyses. Bioinformatics 30: 1844-1849.
8. Emiroğlu, A. O., A. Keskin, and M. Şen. 2018. Experimental investigation of the effects of turkey rendering fat biodiesel on combustion, performance and exhaust emissions of a diesel engine. Fuel 216: 266-273.
9. Fogliarino, M. 2014. Crankcase pressure control in an internal combustion engine: GT-Power simulation.
10. Fu, J., J. Shu, F. Zhou, J. Liu, Z. Xu, and D. Zeng. 2017. Experimental investigation on the effects of compression ratio on in-cylinder combustion process and performance improvement of liquefied methane engine. Applied Thermal Engineering 113: 1208-1218.
11. Hassan, N., M. Rasul, and C. A. Harch. 2015. Modelling and experimental investigation of engine performance and emissions fuelled with biodiesel produced from Australian Beauty Leaf Tree. Fuel 150: 625-635.
12. Hogg, R. V., and J. Ledolter. 1987. Engineering statistics. Macmillan Pub Co.
13. Kelley, C. T. 1999. Iterative methods for optimization. Siam.
14. Muralidharan, K., and D. Vasudevan. 2011. Performance, emission and combustion characteristics of a variable compression ratio engine using methyl esters of waste cooking oil and diesel blends. Applied Energy 88: 3959-3968.
15. Nagaraja, S., M. Sakthivel, and R. Sudhakaran. 2013. Combustion and performance analysis of variable compression ratio engine fueled with preheated palm oil-diesel blends.
16. Nagaraja, S., K. Sooryaprakash, and R. Sudhakaran. 2015. Investigate the effect of compression ratio over the performance and emission characteristics of variable compression ratio engine fueled with preheated palm oil-diesel blends. Procedia Earth and Planetary Science 11: 393-401.
17. Noorollahi, Y., M. Azadbakht, and B. Ghobadian. 2018. The effect of different diesterol (diesel–biodiesel–ethanol) blends on small air-cooled diesel engine performance and its exhaust gases. Energy 142: 196-200.
18. Rao, K. S. 2017. Studying the Effect of Compression Ratio on DI-CI Engine Performance and Emission Characteristics Fueled with Ethanol Blended Diesel. International Journal of Applied Engineering Research 12: 3426-3430.
19. Sayin, C., and M. K. Balki. 2015. Effect of compression ratio on the emission, performance and combustion characteristics of a gasoline engine fueled with iso-butanol/gasoline blends. Energy 82: 550-555.
20. Serin, H., and Ş. Yıldızhan. 2017. Influence of the compression ratio on the performance and emission characteristics of a vcr diesel engine fuelled with alcohol blended fuels. Eur Mech Sci (EMS) 1: 39-46.
21. Singh, D., K. Subramanian, M. Juneja, K. Singh, S. Singh, R. Badola, and N. Singh. 2017. Investigating the effect of fuel cetane number, oxygen content, fuel density, and engine operating variables on NOx emissions of a heavy duty diesel engine. Environmental Progress and Sustainable Energy 36: 214-221.
22. Wu, J., H. M. Wang, L. L. Zhu, and Y. Hua. 2014. Simulation Investigation about Combustion and Emission Characteristics of n-Butanol/Diesel Fuel Mixture on Diesel Engine. Pages 763-768. Applied Mechanics and Materials: Trans Tech Publ.
23. Yang, Z., C. Chu, L. Wang, and Y. Huang. 2015. Effects of H2 addition on combustion and exhaust emissions in a diesel engine. Fuel 139: 190-197.
24. Zhang, X. D., Y. N. Yuan, and J. Y. Du. 2015. Simulation Research of the Effect of Compression Ratios on Combustion and Emission for Methanol/Diesel Dual Fuel Engine. Pages 78-82. Applied Mechanics and Materials: Trans Tech Publ.