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ABSTRACT
The search for alternative fuels (i.e. other than gasoline) is a continuous area of research. In the present work, a comparative study has been conducted by employing a liquid ((G)97) and a gaseous (CNG) fuel in a spark ignition engine. Engine performance, emission. and lubrication oil condition tests have been performed for two fuels by varying operating conditions according to comprehensive sampling plans in each area. Speed was incrementally increased in two phases over the investigated range of rpm for brake power and peak torque. For specific fuel consumption and emission tests, speed was increased through a uniform increment rises over the investigated range of rpm. Lubrication oil samples have been collected over 120 h of engine running with topping for drain out quantity and tests were performed as per ASTM standards. (G)97 showed an improved performance, i.e. 28.8% increase in case of brake power as compared to CNG; however, CNG outperformed (G)97 in case of emission contents and brake-specific fuel consumption (17.2% decrease). Moreover, emission data were fitted to Weibull distribution to ascertain the adequacy for a 95% confidence interval. Furthermore, wear debris (Iron (Fe), aluminum (Al), copper (Cu), chromium (Cr)), lubrication oil condition (kinematic viscosity, flash point and total base number (TBN), and additives depletion (zinc (Zn), calcium (Ca)) showed a visible improvement in case of CNG as compared to (G)97. Lubrication oil analyses depicted 4.9%, 9.5%, and 3.2% reduction in viscosity, flash point, and TBN for (G)97, respectively. However, Fe, Al, and Cu decreased by 12.9%, 29.1%, and 37.7% for CNG, respectively. Mechanisms involved in combustion and lubrication oil deterioration have also been discussed for two fuels.
Nomenclature
| Al | = | Aluminum |
| ASTM | = | American Society for Testing Materials |
| BMEP | = | Brake mean effective pressure |
| BP | = | Brake power |
| bsfc | = | Brake-specific fuel consumption |
| Ca | = | Calcium |
| CI | = | Confidence interval |
| CNG | = | Compressed natural gas |
| CO2 | = | Carbon dioxide |
| CO | = | Carbon monoxide |
| Cr | = | Chromium |
| cSt | = | centiStokes |
| Cu | = | Copper |
| Fe | = | Iron |
| (G)97 | = | Gasoline with 97 octane grade |
| HC | = | Hydrocarbon |
| NOx | = | Oxides of nitrogen |
| ON | = | Octane number |
| rpm | = | Revolution per minute |
| SAE | = | Society of Automotive Engineers |
| Stdev | = | Standard deviation |
| TBN | = | Total base number |
| wt% | = | Weight percentage |
| Zn | = | Zinc |
Declaration of conflicting interests
The authors declare that there is no conflict of interest.
Additional information
Notes on contributors
Muhammad Usman
Muhammad Usman is an Assistant Professor and Ph.D. candidate at Mechanical Engineering Department, University of Engineering and Technology Lahore-Pakistan. His research interest includes Internal Combustion Engine, Energy, Tribology and Environment.
Nasir Hayat
Nasir Hayat is a Professor at Mechanical Engineering Department, University of Engineering and Technology Lahore-Pakistan. Currently, he is chairman of the same department. His research interest includes Energy, Planning and Manufacturing. He has been a visiting Professor to Nanjing University of Aeronautics and Astronautics. He has several widely cited publications.