Experimental Investigation of Low-Carbon and Carbon-Free Fuels In A Spark Ignition Engine

Abstract

The environmental effects of fossil fuel combustion in engines have prompted research into the use of carbon-free and low-carbon alternatives. Extensive research indicates that the world's most challenging problems, such as energy costs, energy security, and climate change, can be effectively addressed by sustainable and alternative energy sources. Several nations conduct valuable research to fulfil their environmental responsibilities through decarbonization. Transportation accounts for a significant share of global energy consumption. These engine fuels are derived from hydrocarbons. Hydrocarbon fuels are hazardous to the environment. Therefore, it is necessary to use low-carbon and carbon-free alternative fuels in internal combustion engines with minimal modifications. Therefore, there is significant international interest in the development of methanol, ammonia, and hydrogen as energy storage mediums for automobiles. Under WOT conditions, the experimental study is carried out in two stages. In the first stage of methanol/LPG, only one phase, the first phase, the influence of variable CR from 12 to 15 is investigated at varying blending ratios from 25% to 45% (LPG) at speeds (1400 rpm to 1800 rpm) while the IT is kept constant at 20ºCA bTDC. The results are examined based on a trade-off between BTE and NOx emissions, and an appropriate operating parameter is determined. In the second stage, ammonia/hydrogen, there are three phases. The first phase containing the influence of variable CR from 12 to 15 is studied at varying blending ratios from 5% to 21% (hydrogen) at speeds of 1400 rpm and 1800 rpm, while the IT remains constant at 24ºCA bTDC. A suitable operational parameter is determined based on a trade-off between BTE and the analysis results. In the subsequent phase, the effect of varying from IT 32ºCA bTDC to 18ºCA bTDC at the blending ratio determined in phase 1 is examined. The appropriate IT and CR are selected for the subsequent stage. In the final stage, various EGR ratios (ranging from 5% to 20%) are investigated for NOx reduction with minimum power loss. In the first stage of the first phase, methanol/LPG showed a rise in BTE with increase in CR from12 to 15 at an ignition timing of 20ºCA bTDC, according to the performance evaluation. With a compression ratio of CR14 to CR15, the experimental data indicate that a SI engine fuelled with methanol/LPG operates smoothly and achieves favourable results. BTE is almost unchanged for CR14 and CR15. Lower-energy-content methanol produces less power than gasoline when the LPG fraction is below 35%. In this instance, methanol/LPG is operated with a higher compression ratio, which significantly impacts the increase in power output compared to a lower CR. However, Pmax and HRRmax are improved when CR, blending percentage, and speed increase. Undoubtedly, methanol's lower carbon content is expected to produce fewer emissions of carbon. In addition, the in-cylinder temperature was decreased, thus contributing to the reduction of NOx emissions. In the second stage of the first phase, the performance evaluation suggests that ammonia/hydrogen showed improvement in BTE at CR15 and 21% hydrogen fraction with the ignition timing of 24ºCA bTDC. Increasing the percentage of hydrogen from 5% to 21% enhances combustion. Consequently, the slow-reaction properties of NH3 are improved. The addition of hydrogen raises the peak temperature; consequently, NOx continues to increase with increasing hydrogen despite the reduction of ammonia. Hence, exhaust after treatment required. During the second phase, the advanced ignition timing improves BP and BTE to a maximum at 28ºCA bTDC. Up to 28ºCA bTDC, the rate of increase in CP and HRR approaches that of TDC. The ignition advance significantly increases NOx emissions at all speeds and CR. BTE is efficient at 28ºCA bTDC and CR15 -16. The methanol/LPG and ammonia/hydrogen-fuelled SI engine compete equally with the gasoline-fuelled SI engine at a relatively higher CR, advanced ignition, and NOx management via EGR implementation. It was a deliberate endeavour to secure energy resources and provide a realistic option for environmentally friendly transportation technologies. It also implies an enormous opportunity to produce and distribute low-carbon and carbon-free alternative fuels.