Abstract
This study experimentally investigates the performance, combustion, and emission characteristics of a single-cylinder diesel engine operated in dual-fuel mode using pyrolysis oil and gaseous hydrogen. Four fuel combinations were examined: neat diesel (100D), diesel–hydrogen (50D50H), diesel–pyrolysis oil (90D10P), and diesel–pyrolysis oil with hydrogen enrichment (90D10P + 50 LPH). The engine was operated at a constant speed of 1,500 rpm under varying load conditions (0–100%), and the results were analysed using response surface methodology (RSM). The 50D50H blend achieved the highest brake thermal efficiency, showing a 21.4% improvement over neat diesel, along with a minimum brake-specific fuel consumption of 0.22 kg/kWh. The maximum in-cylinder pressure (69 bar) and peak heat release rate (75 J/CA) were observed for the 90D10P + 50 LPH blend. Emission analysis indicated that this blend produced the lowest carbon monoxide, carbon dioxide, hydrocarbon, and nitrogen oxide emissions among all tested fuels, while the lowest NOx emission of 350 ppm was recorded for the 50D50H blend. Statistical validation using analysis of variance (ANOVA) yielded regression coefficients (R2) between 0.8 and 1, demonstrating strong agreement between experimental results and model predictions. The findings confirm that the combined application of pyrolysis oil and hydrogen in dual-fuel operation significantly enhances engine efficiency while effectively reducing exhaust emissions.
Data availability
The data that supports the findings of this study are available within the article.
Abbreviations
- ANOVA:
-
Analysis of variance
- BTE:
-
Brake thermal efficiency
- B10:
-
10% Biodiesel + 90% diesel
- B15:
-
15% Biodiesel + 85% diesel
- BSFC:
-
Brake specific fuel consumption
- EGR:
-
Exhaust gas recirculation.
- BDC:
-
Bottom dead centre
- TDC:
-
Top dead centre
- HC:
-
Hydrocarbons
- CO:
-
Carbon monoxide
- CI:
-
Compression ignition
- CA:
-
Crank angle
- CRDI:
-
Common rail direct injection
- CO2 :
-
Carbon dioxide
- DI:
-
Direct ignition
- NOX :
-
Nitrogen oxides
- HRR:
-
Heat release rate
- HHO:
-
Hydroxy gas
- H2 :
-
Hydrogen gas
- LPH:
-
Litres per hour
- LPM:
-
Litres per minute
- LDPE:
-
Low-density polyethylene
- HDPE:
-
High-density polyethylene
- PET:
-
Polyethylene terephthalate
- PVC:
-
Polyvinyl chloride
- RSM:
-
Response surface methodology
- 100D:
-
100% Diesel
- 50D50H:
-
50% Diesel + 50% hydrogen gas
- 90D10P:
-
90% Diesel + 10% pyrolysis oil
- 2D:
-
2 Dimensional
- 3D:
-
3 Dimensional
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Acknowledgements
The authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP.2/246/46.
Funding
The authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP.2/246/46.
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Conceptualization, K.S.K; Writing—Review and Editing, K.S.K, R.S; Formal analysis, M.K, S.K; Investigation, A.I.A.A, A.F.E.
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Kumar, K.S., Surakasi, R., Kareemullah, M. et al. Investigation of hydrogen influence on compression ignition engine fuelled with pyrolysis blends using experimental and RSM methods. Sci Rep (2026). https://doi.org/10.1038/s41598-026-39172-5
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DOI: https://doi.org/10.1038/s41598-026-39172-5