Experimental Investigation into the Effects of N-Pentanol/Diesel Blends on Cyclic Variations in a Multi-Cylinder CRDI Engine

Abstract:

This study experimentally investigates the cyclic combustion variability of n-pentanol and diesel blends in a four-cylinder CRDI diesel engine at a constant speed of 2000 rpm under varying load and injection timing conditions. Two volumetric blends, DP15 and DP25, were evaluated and directly compared with neat diesel (D100) using in-cylinder pressure data recorded over 100 consecutive cycles. Combustion stability was rigorously assessed using the coefficient of variation of the indicated mean effective pressure (COV_IMEP) and the peak cylinder pressure (COV_Pmax), together with continuous wavelet transform (CWT) analysis of the indicated mean effective pressure signals. The results show that cyclic variability decreases significantly with increasing engine load due to improved in-cylinder temperatures, enhanced fuel and air mixing, and reduced ignition delay. Higher variability was observed at low loads, particularly for the pentanol blends. However, at medium loads, the DP25 blend demonstrated lower coefficient of variation values for IMEP and P_max, indicating more stable combustion compared to both baseline diesel and DP15. The average indicated mean effective pressure (IMEP) and peak pressure (P_max) increased proportionally with load for all fuels, with the pentanol blends demonstrating comparable performance to conventional diesel. Furthermore, injection timing was found to significantly influence the cyclic stability, proving that an optimized injection timing strategy vastly improves overall combustion consistency under specific load conditions. Ultimately, n-pentanol and diesel blends, particularly DP25, exhibit comparable combustion performance and improved stability at medium and high loads, clearly indicating their strong potential as suitable, sustainable alternative fuels for CRDI diesel engines.

• Periodical: Key Engineering Materials (Volume 1058)
• Pages: 219-236
• DOI: https://doi.org/10.4028/p-39taZf
• Online since: June 2026
• Authors: Satsimran Singh, Sarbjot Singh Sandhu*
• Keywords: Coefficient of Variation, COV_IMEP, Cyclic Variation, Ignition Delay, Injection Timing, N-Pentanol, P_max

References

[1] Heywood JB. Internal combustion engine fundamentals. 2nd ed. New York, NY, USA: McGraw-Hill Education; 2018.

[2] Singh AP, Mustafi NN, Sharma YC, Agarwal AK. Introduction to Alternative Fuels and Their Utilization Strategies in Internal Combustion Engines. 2020.

DOI: 10.1007/978-981-15-0418-1_1

[3] Campos-Fernandez J, Arnal JM, Gomez J, Lacalle N, Dorado MP. Performance tests of a diesel engine fueled with pentanol/diesel fuel blends. Fuel 2013;107:866–72.

DOI: 10.1016/j.fuel.2013.01.066

[4] Rajesh Kumar B, Saravanan S. Effects of iso-butanol/diesel and n-pentanol/diesel blends on performance and emissions of a di diesel engine under premixed LTC (low temperature combustion) mode. Fuel 2016;170:49–59.

DOI: 10.1016/j.fuel.2015.12.029

[5] Vinod Babu VBM, Madhu Murthy MMK, Amba Prasad Rao G. Butanol and pentanol: The promising biofuels for CI engines – A review. Renewable and Sustainable Energy Reviews 2017;78:1068–88.

DOI: 10.1016/j.rser.2017.05.038

[6] Yilmaz N, Vigil FM, Atmanli A, Donaldson B. Influence of Fuel Oxygenation on Regulated Pollutants and Unregulated Aromatic Compounds with Biodiesel and n-Pentanol Blends. International Journal of Energy Research 2023;2023:3040073.

DOI: 10.1155/2023/3040073

[7] Li X, Guan C, Yang K, Cheung CS, Huang Z. Impact of lower and higher alcohol additions to diesel on the combustion and emissions of a direct-injection diesel engine. Environmental Science and Pollution Research 2019;26:21001–12.

DOI: 10.1007/s11356-019-05275-y

[8] EL-Seesy AI, Waly MS, Nasser A, El-Zoheiry RM. Improvement of the combustion, emission, and stability features of diesel-methanol blends using n-decanol as cosolvent. Scientific Reports 2022;12:1–17.

DOI: 10.1038/s41598-022-20326-0

[9] Zhu J, Wang Z, Li R, Liu S, Hua Y. Experimental study and prediction model of combustion stability and combustion mode variation of burning methanol/biodiesel blends for diesel engines. Fuel 2023;335:127038.

DOI: 10.1016/j.fuel.2022.127038

[10] Hassan QH, Alalwan HA, Mohammed MM, Mohammed MF. Identifying the Impact of Methanol-Diesel Fuel on the Environment Using a Four-Stroke Ci Engine. Journal of Applied Engineering Science 2023;21:188–93.

DOI: 10.5937/jaes0-39809

[11] Olah GA, Goeppert A, Prakash GKS. Beyond Oil and Gas: The Methanol Economy: Second Edition.Wiley-VCH; 2009;44:1–334.

DOI: 10.1002/9783527627806

[12] Imdadul HK, Masjuki HH, Kalam MA, Zulkifli NWM, Alabdulkarem A, Kamruzzaman M, et al. A comparative study of C4 and C5 alcohol treated diesel-biodiesel blends in terms of diesel engine performance and exhaust emission. Fuel 2016;179:281–8.

DOI: 10.1016/j.fuel.2016.04.003

[13] Wei L, Cheung CS, Huang Z. Effect of n-pentanol addition on the combustion, performance and emission characteristics of a direct-injection diesel engine. Energy 2014;70:172–80.

DOI: 10.1016/j.energy.2014.03.106

[14] Yilmaz N, Atmanli A. Experimental evaluation of a diesel engine running on the blends of diesel and pentanol as a next generation higher alcohol. Fuel 2017;210:75–82.

DOI: 10.1016/j.fuel.2017.08.051

[15] Kaul BC, Lawler BJ, Finney CEA, Edwards ML, Wagner RM. Effects of Data Quality Reduction on Feedback Metrics for Advanced Combustion Control. SAE Technical Paper 2014-01-2707; 2014.

DOI: 10.4271/2014-01-2707

[16] Kyrtatos P, Brückner C, Boulouchos K. Cycle-to-cycle variations in diesel engines. Applied Energy 2016;171:120–32.

DOI: 10.1016/j.apenergy.2016.03.015

[17] Maurya RK. Combustion Stability Analysis. In: Maurya RK, editor. Cham: Springer International Publishing; 2019, p.361–459.

DOI: 10.1007/978-3-030-11954-6_8

[18] Maurya RK. Characteristics and control of low temperature combustion engines: Employing gasoline, ethanol and methanol. Cham: Springer International Publishing; 2017.

DOI: 10.1007/978-3-319-68508-3

[19] Maurya RK, Saxena MR, Akhil N. Intelligent Systems Technologies and Applications. Advances in Intelligent Systems and Computing 2016;384:247–57.

DOI: 10.1007/978-3-319-23036-8

[20] Kumar P, Singh Sandhu S. An attempt to implement partially premixed combustion strategy in a multi-cylinder CRDI engine: A detailed experimental and wavelet transform analysis. Fuel 2022;323:124372.

DOI: 10.1016/j.fuel.2022.124372

[21] Erdiwansyah, Mamat R, Sani MSM, Sudhakar K, Kadarohman A, Sardjono RE. An overview of Higher alcohol and biodiesel as alternative fuels in engines. Energy Reports 2019;5:467–79.

DOI: 10.1016/j.egyr.2019.04.009

[22] Kumar P, Singh M, Sandhu SS. Wavelet analysis for cyclic combustion dynamics of a multi-cylinder CRDI diesel engine fuelled with a blending of argemone biodiesel-diesel oil. Chaos 2022;32:023113.

DOI: 10.1063/5.0080910

[23] Surisetty VR, Dalai AK, Kozinski J. Alcohols as alternative fuels: An overview. Applied Catalysis A: General 2011;404:1–11.

DOI: 10.1016/j.apcata.2011.07.021

[24] Sahu TK, Shukla PC, Belgiorno G, Maurya RK. Alcohols as alternative fuels in compression ignition engines for sustainable transportation: a review. Energy Sources, Part A: Recovery, Utilization and Environmental Effects 2022;44:8736–59.

DOI: 10.1080/15567036.2022.2124326

[25] Zhang Y, Gao S, Zhang Z, Li W, Yuan T, Tan D, et al. A comprehensive review on combustion, performance and emission aspects of higher alcohols and its additive effect on the diesel engine. Fuel 2023;335:127011.

DOI: 10.1016/j.fuel.2022.127011

[26] Rajesh Kumar B, Saravanan S. Use of higher alcohol biofuels in diesel engines: A review. Renewable and Sustainable Energy Reviews 2016;60:84–115.

DOI: 10.1016/j.rser.2016.01.085

[27] Lapuerta M, Rodríguez-Fernández J, Fernández-Rodríguez D, Patiño-Camino R. Modeling viscosity of butanol and ethanol blends with diesel and biodiesel fuels. Fuel 2017;199:332–8.

DOI: 10.1016/j.fuel.2017.02.101

[28] Saxena MR, Maurya RK. Performance, Combustion, and Emissions Characteristics of Conventional Diesel Engine Using Butanol Blends. Energy, Environment, and Sustainability 2018:93–110.

DOI: 10.1007/978-981-10-7575-9_5

[29] Şanlı A. Experimental study of combustion and cyclic variations in a CRDI engine fueled with heptanol/iso-propanol/butanol and diesel blends. Energy 2023;269.

DOI: 10.1016/j.energy.2023.126800

[30] Sharma A, Kumar P, Sandhu SS, Singh M. Experimental investigation into the effects of Argemone biodiesel/diesel blends on cyclic variations in a multi-cylinder CRDI engine. Clean Energy 2023;7:363–74.

DOI: 10.1093/ce/zkac081

[31] Gnanamoorthi V, Marudhan NM, Gobalakichenin D. Effect of combustion chamber geometry on performance, combustion, and emission of direct injection diesel engine with ethanol-diesel blend. Thermal Science 2016;20:S937–46.

DOI: 10.2298/TSCI16S4937G

[32] Giakoumis EG, Rakopoulos CD, Dimaratos AM, Rakopoulos DC. Exhaust emissions with ethanol or n-butanol diesel fuel blends during transient operation: A review. Renewable and Sustainable Energy Reviews 2013;17:170–90.

DOI: 10.1016/j.rser.2012.09.017

[33] Duan X, Feng L, Xia Y. The mechanism and effect factors of the combustion cycle-to-cycle variations in the spark ignition engine. Energy Science and Engineering 2024;12:4773–87.

DOI: 10.1002/ese3.1879

[34] Gürgen S, Ünver B, Altın İ. Prediction of cyclic variability in a diesel engine fueled with n-butanol and diesel fuel blends using artificial neural network. Renewable Energy 2018;117:538–44.

DOI: 10.1016/j.renene.2017.10.101

[35] Sen AK, Longwic R, Litak G, Górski K. Analysis of cycle-to-cycle pressure oscillations in a diesel engine. Mechanical Systems and Signal Processing 2008;22:362–73.

DOI: 10.1016/j.ymssp.2007.07.015

[36] Górski K, Smigins R, Matijošius J, Tziourtzioumis D. Cycle-to-Cycle Variation of the Combustion Process in a Diesel Engine Fueled with Rapeseed Oil—Diethyl Ether Blends. Energies 2023;16.

DOI: 10.3390/en16020720

[37] Saxena MR, Maurya RK. Determination of cyclic air-fuel ratio and analysis of low and high-frequency variations in dual-fuel RCCI engine. International Journal of Engine Research 2024;25:2230–48.

DOI: 10.1177/14680874241267345

[38] Ali OM, Mamat R, Masjuki HH, Abdullah AA. Analysis of blended fuel properties and cycle-to-cycle variation in a diesel engine with a diethyl ether additive. Energy Conversion and Management 2016;108:511–9.

DOI: 10.1016/j.enconman.2015.11.035

[39] Saxena MR, Maurya RK. Characterization of Cycle-to-Cycle Variations in Conventional Diesel Engine Using Wavelets. Energy, Environment, and Sustainability 2018:135–55.

DOI: 10.1007/978-981-10-7575-9_7

[40] Maurya RK, Akhil N. Experimental Investigation on Effect of Compression Ratio, Injection Pressure and Engine Load on Cyclic Variations in Diesel Engine Using Wavelets. SAE Technical Papers 2017:1–13.

DOI: 10.4271/2018-01-5007