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ABSTRACT
To resolve power reduction and engine knock, we investigate the influence of adding ethanol to the natural gas (NG)-air mixture on the combustion and emissions of NG-diesel dual-fuel (NDDF) engines by numerical analysis. The baseline engine is a 4-cylinder diesel engine. NG and ethanol fuels are injected into the intake port, while diesel fuel is injected directly into the cylinder. The simulation is performed using GT-Power software, and the results are validated using experimental data. The engine speeds are set at 1000, 1800, and 2800 rpm. The engine loads are set at 50% and 75%. The diesel injection ratios are 10% and 20%. The ethanol substitution rate (ESR) varies from 0% to 60% with an interval of 10%. The results indicate that combustion and emissions are improved with the increase in ESR. First, the engine knock is reduced since the maximum pressure rise rate (MPRR) decreases. Second, the power performance and economy performance of the NDDF engine is improved because the indicated thermal efficiency (ITE) and brake mean effective pressure (BMEP) increase. In addition, although the emissions of the NG-ethanol-diesel ternary-fuel engine are higher than that of NDDF engines, some emissions, such as nitrogen oxide (NOx) emissions and carbon monoxide (CO) emissions, are lower than that of pure diesel engines. This suggests that the addition of ethanol can improve the power and economic performance of NDDF engines.
Highlights
The combustion and emission of NG diesel engine at medium and high load under different ESRs were studied.
Adding ESR will decrease MPRR under medium and high load.
Increasing ESR has a positive impact on ITE and BMEP under medium and high load.
Increasing ESR will increase emissions, and NOx and CO emissions are lower than pure fuel mode.
Nomenclature
| TDC | = | Top dead center |
| ATDC | = | After TDC |
| BTDC | = | Before TDC |
| BMEP | = | Brake mean effective pressure |
| CA10 | = | Crank angle at which 10% of the fuel has burnt |
| CO2 | = | Carbon dioxide |
| CO | = | Carbon monoxide |
| D10 | = | The energy ratio of diesel input is 10%, while the energy ratio of other fuels input is 90% |
| D20 | = | The energy ratio of diesel input is 20%, while the energy ratio of other fuels input is 80% |
| E0 | = | In the mixture of ethanol and NG fuel, the energy ratio of ethanol input is 0% |
| E60 | = | In the mixture of ethanol and NG fuel, the energy ratio of ethanol input is 60% |
| ESR | = | Ethanol substitution rate |
| ESR | = | Ethanol substitution rate |
| HRR | = | Heat release rate |
| HC | = | Hydrocarbons |
| ITE | = | Indicated thermal efficiency |
| MPRR | = | Maximum pressure rise rate |
| NDDF | = | NG-diesel dual-fuel |
| NG | = | Nature gas |
| NSR | = | Nature gas substitution rate |
| NOX | = | Nitrogen oxides |
| PCP | = | Peak cylinder pressure |
| PCT | = | Peak cylinder temperature |
| LHV | = | latent heat of vaporization |
Acknowledgements
This work was supported by Science and technology research project of Hebei higher education（grant number ZD2017201), Natural Science Foundation of Hebei Province (grant number E2015409022), and Natural Science Foundation of Tianjin City (grant number 16JCTPJC48700).
Disclosure statement
No potential conflict of interest was reported by the authors.
Data availability statement
The authors declare the data that support the findings of this study are available from the corresponding author upon reasonable request https://doi.org/10.1080/15567036.203.2221192
Credit Contributions
Mengyuan Zhang: Writing – original draft (equal); investigation (equal). Yunjing Jiao: Funding acquisition (equal); methodology (lead). Yuanli Xu: Conceptualization (lead); funding acquisition (lead); writing – review and editing (lead). Xiaofan Xu: Formal analysis (lead); software (lead). Baoxing Guo: Validation (lead); supervision (lead).
Additional information
Funding
Notes on contributors
Mengyuan Zhang
Mr. Mengyuan Zhang is a master student at Tianjin University of Science & Technology.
Yunjing Jiao
Dr. Yunjing Jiao is an associate professor at North China Institute of Aerospace Engineering.
Yuanli Xu
Dr. Yuanli Xu is an associate professor at Tianjin University of Science & Technology.
Xiaofan Xu
Mr. Xiaofan Xu is a master student at Tianjin University of Science & Technology.
Baoxing Guo
Mr. Baoxing Guo is a master student at Tianjin University of Science & Technology.