Performance Assessment of Petrol Engines with Hydrogen as an Alternative Fuel

The energy demand is increasing day by day with the increase of the world population. Due to this, it not only reduces current energy reserves but also increases energy losses. Due to the determinate potential of oil reserves, it is necessary to increase the use of alternative fuels. The use of hydrogen in combination with petroleum-derived fuels in internal combustion engines can reduce harmful exhaust emissions from fossil fuels. Therefore, researchers continue to work for an economic and safe fuel that does not harm the environment.

Ravi et al. [1] modified single-cylinder compression ignition engine to work as lean burn spark ignition engines that run on LPG and substitute hydrogen for oxygen. Different compression ratios were used for keeping the speed constant and observed that for high compression ratios the emissions were found less when combined with hydrogen with a compression ratio 10.5:1 as optimal. The brake thermal power and brake thermal efficiency were increased. At lower loads the thermal efficiency was reduced. By adding hydrogen, the combustion rate was enhanced. The emissions of carbon monoxide, carbon dioxide and NO were reduced considerably. Jain et al. [2] assessed the effect of split fuel addition and EGR on PCCI combustion, the study tested different start of main injection and pilot injection timings as well as EGR rates. The findings suggest that the best injection timing and EGR rate combinations can optimize PCCI combustion. Patil et al. [3] conducted a test using oxy hydrogen (HHO) in a spark ignition engine to understand the performance. HHO gas was generated by the electrolysis of water with KOH solution as the catalyst and allowed it to mix with a fresh stream of air before the inlet of the carburetor. The generation of gas was controlled by varying supply of current. The Author observed that HHO can be easily integrated with spark ignition engine. Author has controlled the flow of HHO with 9Amps current throughout the experiment. It was observed that the engine performance was improved with on the introduction of HHO gas. It was found that there was an increase in brake thermal efficiency by 10.82% and the brake specific fuel consumption was decreased by 9.74%. As the volumetric efficiency is concerned a 3% decrement was observed. Su et al. [4] explored the effect of spark timing on the efficiency of a dual-fuel H₂-gasoline rotary engine. To conduct experiment a rotary engine was set up with port fuel injection along with an electronic management module to control fuel injection, excess air ratio and hydrogen volume fraction. The engine was operated at 4500 rpm and with an absolute pressure of 35kPa. The author observed that for a specified volumetric percentage peak cycle pressure, the chamber temperature was increased the brake thermal efficiency was increased initially and then decreased when advancement took in spark. The emissions of NO and HC are reduced after retarding the spark. Yan et al. [5] researched on hydrogen enriched natural gas (HCNG) in spark ignition engines as hydrogen has shorter ignition delay, minimum ignition energy and higher laminar speed which enhances the complete combustion and leads to higher thermal efficiency and low NO emissions. Mixing of hydrogen with transport fuels such as gasoline, biogas, diesel and alcohols improved in cylinder combustion with minimum emissions. Abhijna et al. [6] generated gas from electrolysis of water and used in the bike as a fuel with the mixture of air and petrol to understand the viability in terms of performance and emissions. It is observed that there was an increase in fuel efficiency of 5 to 10% by reducing pollutants. Vinoth and Paturu [7] provided an overview of current advancements in the research of hydrogen-powered internal combustion engines. Advances in direct hydrogen injection, in-cylinder heat transfer, modeling, and combustion techniques at both the engine and vehicle levels are included in the overview. These research efforts led to excellent efficiency and emissions that are well within regulatory limitations, as well as satisfactory specific power outputs. Mourad and Mahmoud [8] performed experiments on four-stroke petrol engines using blends of propanol and gasoline up to 15% under various load conditions. Authors observed that the propanol added to petrol had improved the fuel economy by 2.84% for a blend ratio 15%, and there was a reduction in pollutants hydrocarbons and carbon monoxide 14.18% and 10.87% respectively. Mahendran et al. [9] evaluated various assumptions regarding the structure and content of HHO gas, explore the laws of combustion and chemical processes of electrolytic reactions, and suggested design and implementation factors to enhance the gas production percentage and introduced engine systems that uses HHO gas. System complexity, safety, expense, and electrolysis efficiency are cited as the primary hurdles in employing HHO gas in engines. By using HHO engine torque, power and thermal efficiency have been increased by reducing NO, CO and HC. Ismaila et al. [10] focused on unburned hydrocarbons which are the major pollutants in the form of exhaust gases. Brown gas which is a mixture of hydrogen and oxygen was used as a new source of energy for complete combustion of the mixture and used dry cell of HHO because its advantages such as compact and easy to install in engines. HHO gas is produced from water and which will be ionized by NaOH as an electrolyte. Finally, it is observed that there was a reduction of fuel consumption by 17% reduction in CO, 27% reduction in HC, 15% increase in O₂ and 1% increase in CO₂. Nadaleti and Przybyla [11] explored the possible use of rice industrial waste, which includes husk and effluent, to generate biogas and syngas with a high hydrogen concentration. These gasses or their combinations can be used to fuel SI, taking benefit of the rice industry's potential of bioenergy. The study conducted engine testing with common biogas and syngas compositions and discovered that increasing the surplus ratio (l) value from 1 to 1.25 reduces carbon monoxide and NOx pollutants while boosting the stated efficiency. Yu et al. [12] investigated three possible injection modes as petrol, petrol plus homogenous hydrogen, and petrol plus stratified hydrogen. The results demonstrated that adding hydrogen raised NOx emissions, while reducing CO and HC pollutants and boosting brake thermal efficiency, since the combustion temperature is higher. The stratified hydrogen mode with petrol improved brake thermal efficiency, flame expansion duration, fast combustion duration, and COV over the homogeneous hydrogen mode. Increased in NOx and CO due to denser concentrations of hydrogen near the ignition switch and leaner concentrations near the wall were also observed. Akal et al. [13] worked on hydrogen as an alternative fuel for the forthcoming generations by keeping in mind the requirement of energy which is pollution free. The Author conducted experiments on petrol, liquefied petroleum gas and diesel. When hydrogen was added to petrol and liquefied petroleum gas and diesel the torque and power were increased in petrol engines, whereas decreased in liquefied petroleum and diesel engines. As the emission part is concerned in petrol and LPG are decreased, whereas in diesel engines NO levels are increased. Przybyła and Nadaleti [14] conducted experiments using low calorific value gas in a spark ignition engine. This low calorific value gas is simulated by the mixture of carbon monoxide, hydrogen and nitrogen. The Author conducted experiment on single cylinder GX270 honda engine. Engine operation was controlled by a microprocessor controller and was constant speed of 3000 rpm. No impact on internal parameters was observed, if the duration of inert gas increased led to increase in NO emissions and reduced HC, CO emissions. Lhuillier et al. [15] worked experimentally on combustion and emissions of a spark ignition engine with premixed ammonia and hydrogen. Ammonia gas blends in different ranges have been mixed with hydrogen and tests were conducted. It is observed that 20% by volume of hydrogen improved the stability of combustion by avoiding misfires along with good indicated efficiency. Krishna et al. [16] focused on an alternative fuel to reduce emissions led to global warming in which hydroxy gas produced by electrolysis was used as an alternative fuel to deplete hydrocarbon emissions in a variable compression gasoline engine. The compression ratios varying from 7 to 10 show a decrement in fuel consumption and improved brake thermal efficiency. The calorific value of the fuel has been increased by adding hydroxy gas. Emissions such as CO, O₂ and unburnt gases are decreased with slight an increase in NO emissions because of the high temperature in the combustion chamber. Masuk et al. [17] addressed various fuel usages in petrol engines and compared brake thermal efficiency, brake specific fuel consumption, compression ratio and torque and toxic emissions. Every fuel has their own individual benefits using different fuels like hydrogen, natural gas, propane and bio-gas. It is observed that hydrogen and propane can run at higher compression ratio than petrol fuel as the octane number is more for hydrogen. Bharath et al. [18] worked on methanol-gasoline mix on engine efficiency and emissions, both with and without additions. Methanol-gasoline blend fuels have been shown increased engine performance and lower pollution. Low alcohol concentrations can lead to problems like corrosion, phase separation, and increased fuel use. Stepien [19] examined the most recent findings on the use of H₂ as a fuel in ICEs, compiled the knowledge and viewpoints of international research institutions on the scientific feasibility of using H₂ in ICEs, and offers a summary of the benefits and drawbacks of using H₂ as a solution. The study analyzes the unique physical, chemical, and functional features of H₂ for IC engines and offers a critical evaluation of H₂ combustion approaches, concentrating on the difficulties and potential related to port and direct hydrogen injection technology. It is seen that hydrogen is suitable as an alternative energy source to improve the performance and greatly to reduce emissions. Salek et al. [20] worked on the hydrogen/gasoline dual-fueled engine would be affected by water injection and changes to the start of combustion. Utilizing the AVL BOOST programme, the engine is simulated and tested against experimental data. Genetic algorithm (GA) and multiobjective optimization was used to find the best water injection and start of combustion values for different H₂ energy shares. The findings demonstrate that the suggested solution increases the mean effective pressure and effectiveness of the brake, with an increase in engine equivalent brake specific fuel consumption of up to 4.61% without any pollutants. Zang et al. [21] observed that the cost of hydrogen is the biggest influence based on the FT fuel's lowest retail price. By 2050, the manufacturing of FT fuel could be cost-effective compared to pretax petroleum diesel pricing at a cost of \$0.8/kg for H₂. The report also said, that enhancing H₂ and CO₂ recycling contributions should be the main goal of future system optimization. Du et al. [22] reviewed different versions of current standards concerning H₂ for fuel cell vehicles in China and abroad furthermore, the causes and developing trends are analyzed for the changes in these standards in detail. On the other hand, according to characteristics of H₂ for fuel cell vehicles, standard H₂ purification technologies, such as pressure swing adsorption (PSA), membrane separation and metal hydride separation, were analyzed, and the latest research progress was reviewed. Fan et al. [23] addressed the energy needs, nations like Japan, Korea, and China are actively creating hydrogen infrastructure. PEMFCs, which are economically feasible for automotive applications, are the main topic of the article. The discussion focuses on automotive applications while covering all essential PEMFC components, temperature and water control, and associated characterization approaches.

Due to the depletion of conventional fuels, different researchers worked on alternative ways to improve the fuel resources. Research shows exhaustive performed work on diesel and petrol engines with diverse combination of fuels like LPG along with petrol and diesel. Some of the researcher added hydrogen with petrol with constant compression ratios and also obtained variation in the compression ratios. Some of the researchers worked with split type injection with exhaust gas recirculation with PCCI and also by using HHO, propane, stratified hydrogen to improve performance on enhanced combustion process. Based on the literature review, in this work experiment are performed by injecting hydrogen in two phases with varied quantities to improve the performance with reduced pollutants.

Figure 4 shows the indicated brake and frictional power at different speeds. At 1150 rpm the brake power, frictional power and indicated power were noted as 3.02, 3, and 3.05kW respectively. The frictional power slowly increased from 1150 rpm and reached to a maximum at 1620 rpm with a value of 3.3kW and suddenly decrement started at 1620 rpm and slowly decreased to 3.25 at 1800 rpm. The indicated power at 1150 rpm was observed as 3.06kW and gradually increased to 1620 rpm with a maximum value of 7.5kW and further also increased till 1800 rpm with a further maximum value7.6kW. Brake power was increased from 1150 rpm to 1400 rpm and further increased to 1620 rpm to 4.1kW and further too increased to 4.3kW at 1800 rpm. At maximum speed the brake power and indicated power have shown similar values because at higher rpm the power developed gets increased.

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Figure 4. Variation of IP, BP, FP with speed for petrol engine

Figure 4 shows on X axis speed and on Y axis indicated, brake and frictional power. In this particular software three parameters comes directly on Y axis.

Before commencing the experiment, we have changed the gaskets and piston rings of the engine and we added the hydrogen in addition to the normal fuel which is being taken inside the engine the hence the compression ratio gets increased more over clean and complete combustion might have taken place. Hence there might be an increment in indicated power and indicated mean effective pressure.

At the lower rpm the indicated, the frictional mean effective pressures are low. As the speed increases the gradual increment in pressure and reaches to a maximum of 8.474bar and 3.74bar respectively, at 1610 rpm and a pressure fall was observed afterword.

From Figure 5 it is observed that the brake mean effective pressure was more at the lower speed and later a great reduction was observed at high speed (1800rpm) due to increased friction. It is observed that the friction at rated power was significantly higher than at peak torque speed. From Figure 6 full load condition, the brake thermal and indicated thermal efficiency are found to be 30.4% and 28.4%, respectively. The brake thermal efficiency decreases as the speed of the engine increases. This may be due to the increase in mechanical friction. These two curves are quite reverse to each other. From Figure 7 at full load with respect to speed condition, torque, mechanical efficiency and volumetric efficiency are found as 25.8N-m, 63% and 59%. As the speed increases, the torque and volumetric efficiency decrease at full load. The mechanical efficiency decreases rapidly up to 1600 rpm from 1100 rpm and increases gradually to 57.2% until it reaches minimum load. The decrement of mechanical efficiency at higher rpm is due to the losses of eddy current.

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Figure 5. Variation of IMEP, BMEP, FMEP with speed

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Figure 6. Variation of Indicated, and brake thermal efficiency speed

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Figure 7. Variation of torque, mechanical & volumetric efficiencies with speed

From Table 4, at full load NO and soot were observed lesser as compared to other loading conditions. NO was found to be 890 ppm and soot was observed 0.2 ppm. Carbon monoxide was observed higher when compared to other loads. The reason for the increase in CO and CO₂ is due to the almost complete combustion in the combustion chamber. Hydrocarbons are slightly higher compared to 75% of the load because of some particles which are unburnt.

3.1 Hydrogen injection along with petrol for 216 gm/hour

From hydrogen cylinder look up table connects system which converts valve into values. The time for seconds we can set manually in the system according the hydrogen cylinder opens and closes. If we don’t want, we need to keep these values as zero. Additional cost incurring parameters are hydrogen cylinder with look up table system and hydrogen gas. From Figure 8, it is observed that the brake power is varying linearly from zero to full load. When only petrol is used as fuel and the similar is the case when hydrogen was injected at a rate of 216 gm/hour, then the brake power increased from 3.1kW to 3.3kW. The increased power was due to the injection of hydrogen in the combustion process as compared to petrol injection only as a fuel.

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Figure 8. Variation of IP, BP, FP with speed for petrol + H₂ at 2ms

From Figure 9, the brake mean effective pressure increases linearly from zero load to 1/3 (one third) initially and reached to 5 bars at full load and this value was slightly increased approximately 20% compared to petrol as fuel. From Figure 8 the brake thermal efficiency was increased from 30.4% to 35% with the addition of hydrogen as the mass of the fuel kept constant. There was an increment of 15.1% in brake thermal efficiency and this may be due to the intake charge of petrol along with hydrogen.

From Figure 10, at 1725 rpm if we consider the BMEP value is 4.58bars, IMEP value is 9 bars and FMEP is 4.4 bars at 25% load. At full load that is at 1200 rpm the BMEP is 4.99bars, IMEP is 6.6bars and FMEP is 1.6 bars. At any given speed the values of BMEP, IMEP and FMEP are satisfying the power calculations.

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Figure 9. Variation of IMEP, BMEP, and FMEP speed for petrol+ H₂ at 216 gm/hour

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Figure 10. Variation of Indicated and brake thermal efficiency with speed for petrol+ H₂ at 2ms

From Figure 11, it is observed that the torque values increased from 25.8 to 26.3 N-m at full load. The mechanical efficiency was increased from 63% to 75%. Similarly, the volumetric efficiency was also increased from 62.3% to 82.5% at full load condition. The improvement in all parameters was due to better fuel combustion, when hydrogen was injected which makes the engine more responsive and faster which in turn increases the engine horse power and leads to directly improve all three parameters. Table 5 presents the emissions for petrol + hydrogen 216gm/hour.

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Figure 11. Variation of torque, mechanical efficiency and volumetric efficiency with speed for petrol+ H₂ at 216 grams per hour

3.2 Petrol + H₂ at 270 gm/hour

From Figure 12, at full load condition, the brake power, the indicated and frictional power was observed as 3.3kW, 5.2kW, and 2kW, respectively when the hydrogen was injected at a rate of 270 gm/hour. From Figure 13, BMEP, IMEP and FMEP were found 5bars, 8 bars and 3bars respectively. Compared to 216 gm/hour injection there was increment in indicated and brake power by 15.5% and 6.16% respectively when injection of hydrogen at a rate of 270 gm/hour. The improvement in the combustion process with the help of hydrogen led to the increment in power.

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Figure 12. Variation of IP, BP, and FP with speed

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Figure 13. Variation of IMEP, BMEP, and FMEP with speed

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Figure 14. Variation of indicated and brake thermal efficiency with speed

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Figure 15. Variation of torque, mechanical efficiency and volumetric efficiency with speed

Table 6. Emissions for petrol + hydrogen 270 gm/hour

Thermal efficiency is input heat energy and mechanical efficiency is output of the engine which will be lesser than thermal energy as losses is involved in it.

From Figure 13, at full load condition the indicated mean effective pressure was increased by 19% compared to 216 gm/hour hydrogen injection. It was observed that there was no change in brake mean effective pressure. From Figure 14, at full load condition the indicated thermal efficiency was increased by 16.2% comparatively to 216 gm of hydrogen injection. Similarly, there was a small increment in the brake thermal efficiency of 4.1% to in this case. It is observed that, both the efficiencies were increased in this case. Table 6 presents the emissions for petrol + hydrogen 270 gm/hour. From the Figure 15, at full load the torque was increased by 6.4% comparatively and there was decrement of mechanical efficiency by 15%, whereas the volumetric efficiency was good for the pure petrol only.