2. Thesis and Dissertations
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Item Experimental Studies on Magnetic Field Assisted Combustion of Hydrocarbon Fuels in a Multicylinder Spark Ignition Engine under Liquid Phase and Gas Phase Operation(National Institute of Technology Karnataka, Surathkal, 2021) Oommen, Libin P.; N, Kumar G.Global energy demand forecasts indicate a growing trend with the ever-rising population and technology that enriches our everyday lives. Ironically, the rise in energy demand is 1.52 per cent per annum relative to the 1.14 per cent growth in population. Fossil oil, being the basic engine of industrial revolution, now meets more than 80 percent of global energy demand. The fossil energy is majorly used in the transport field in Internal Combustion Engines. With the rising trend of individuals using private cars, this share is expected to increase even higher, putting a burden on the energy sources. The over reliance on fossil fuels is so high that in a few decades the fossil reserves are predicted to become exhausted. Studies indicate that the transport industry itself using internal combustion engines contributes to 45 percent of India's overall air pollution. The rapid population growth and increased use of private vehicles has accounted for the countrywide deterioration of air quality. The combustion of fossil fuels in motors leads to the release of harmful contaminants such as CO, HC, CO2, NOx and PM of which the percentage content is increasing every year. The transition to e-mobility is challenging and is dependent on path breaking technologies and renewable energy penetration. This is the reason that provokes us to focus our research on the efficient utilization of existing fossil fuel energy and to come up with technologies that improve the fuel economy as well as the emission levels of internal combustion engines. The present research experimentally investigates the effect of a physical pre-treatment technique of hydrocarbon fuels before combustion in I.C. Engines using high intensity magnetic fields. The performance, combustion and emission characteristics of the engine under varying intensities of uniform magnetic fields created by high grade (N38) NdFeB are studied at four different loads (25%, 50%, 75% and 100%) and four different engine speeds (2000 rpm, 2500 rpm, 3000 rpm and 3500 rpm). The impact of magnetisation pattern on combustion parameters is analyzed by switching between two different patterns (axial and radial) of magnetisation exclusively. The influence of magnetic fields on liquid phase and gaseous phase combustion are analyzed separately by fuelling the iv engine with gasoline and LPG exclusively with the aid of suitable engine modifications. The effect of a post combustion treatment technique like part cooled exhaust gas recirculation is studied to come up with an optimal flow rate which benefits the combustion and emission of both liquid and gaseous phase fuels and is integrated with the optimal parameters in magnetic field assisted combustion to investigate the synergetic effect produced on the combustion of gasoline as well as liquefied petroleum gas. The experiments are conducted on a 10L inline Maruthi Suzuki Zen MPFI spark ignition engine which has modified provisions to operate on neat LPG. A separate gas ECU is provided for the switching between fuel phases. The input given to the gas ECU is the opening signal pulse from the already deployed gasoline ECU which is then modified with a correction factor before being sent to the gas injectors. Four distinct gas injectors are provided in the inlet manifold adjacent to the inlet port of individual cylinders for injecting LPG. These gas injectors are maneuvered by solenoid valves driven by 12V DC supply. The specifications of the gas injectors like nozzle diameter are designed corresponding to power generated per cylinder. Correspondingly injectors of nozzle diameter 1.75 mm is chosen for the given test engine. The NdFeB magnets of a particular magnetisation pattern are mounted on the fuel line with a non magnetic stainless steel covering adjacent to the fuel injector. A system for recirculating partially cooled exhaust gases into the combustion zone is designed for our experimentation. Prior to the data acquisition, the engine is operated for some time to reach steady state operation. Experimental error is minimized by taking average value of three readings at each test points. Initially experiments are conducted to study the performance, combustion and emission characteristics of the engine with axial magnetic fields applied on liquid phase hydrocarbons at various load and speed conditions. In the subsequent stages, the engine is fueled by gas phase hydrocarbons and then the axial fields are replaced using radial fields on both fuel phases. In the next part of investigation, the effect of locus of magnetisation is studied with respect to a single fuel phase. The optimal flow rate of part cooled EGR is v experimentally estimated for both fuel phases which is then integrated with the initially optimized parameters of magnetic fields and experimented in the final phase. Experimental results show that the effect of magnetic field assisted combustion is much more pronounced in the case of liquid phase hydrocarbons, owing to the continuous arrangement of hydrocarbon molecules in the liquid phase. Radial magnetisation pattern is observed to be more effective in molecular restructuring in both the fuel phases because of its ability to ionize the molecules in all directions. Magnetic field assisted combustion proves to be beneficial in improving the fuel economy and thermal efficiency of the engine under both fuel phases. Experimental results also indicate that recirculation of partially cooled exhaust gases are beneficial in enhancing the combustion and emission characteristics of the engine up to an optimum limit and are particularly useful in the reduction of oxides of nitrogen which in the normal case is enormous in LPG combustion. The synergetic effect of both these techniques is especially beneficial in terms of fuel economy, thermal efficiency and NOx emissions of the engine under both phases of hydrocarbons.Item Performance and Emission Characteristics of a Multi-Cylinder Si Engine on Gasoline-Lpg Dual Fuel Mode of Operation(National Institute of Technology Karnataka, Surathkal, 2017) Nayak, Vighnesha; Mohanan, P.Population growth over the last decades has led to tremendous growth in fossil energy demand with increased industrialization and use of vehicles. The most common fuel for internal combustion engines is still made out of oil, but continuous increases in oil prices has increased interest in alternative fuels. Strict international regulations on emissions and improving the combustion efficiency, gaseous fuels found to be better alternative fuel for conventional fuel. Gaseous fuels are promising alternative fuels due to their economic costs, high octane numbers, higher heating values and lower polluting exhaust emissions. LPG, as a relatively clean fuel, is considered one of the most promising alternative automotive fuels because of its emission reduction potential and lower price than gasoline. Turbocharger plays vital role in enhancing the boost pressure of IC engines. Turbocharging the engine will improve the combustion characteristics and reduces the NOX emission. Dilution of intake charge is the one of the method to reduce NOX emission. Vaporised watermethanol induction is used to reduce the emissions from the engine. The present study deals with experimental investigations of LPG-gasoline dual fuel mode of operation on engine performance, combustion and emission characteristics with turbocharging and vaporized water-methanol induction. A stationary four stroke, four cylinders, MPFI engine capable of developing 44 kW at 6000 rpm has been modified to operate on LPG fuel. A separate gas ECU has been developed with software to operate dual fuel mode of operation. The engine operating parameters of speed, load conditions and static ignition timings are varied. A turbocharger is selected based on the exhaust mass flow energy of the engine and installed in the experimental test rig with necessary modification in the intake and exhaust manifold. The waste heat from the exhaust gas has been used to generate vapor from water-methanol mixture and induced into the intake manifold to reduce the emissions from the engine. Initially experiments are conducted to study the performance, combustion, cycle by cycle variations and emission characteristics of the test engine fueled with different percentage of LPG by mass viz: 0%, 25%, 50%, 75% and 100%. In the next part of investigation, static ignition timings are advanced from 5 deg. bTDC to 8 deg.iv bTDC and 11 deg. bTDC to analyze performance and emission characteristics. During this stage percentage of LPG and static ignition timing are optimized based on performance and emission characteristics. Experiments are conducted at full load and part loads in the engine speed range of 2000 rpm to 4500 rpm. In third stage of research, a turbocharger is installed and conducted the experiment for optimized conditions. In the last part of the investigations, the engine tests are conducted with vaporized water-methanol induction. The waste heat from the exhaust gas has been used to generate vapor from deionized water-methanol mixture. Vapor to LPG flow rates of 10, 20 and 30% (on volume basis) are used. The vapor is mixed with the intake air in the intake manifold of the engine. From experimental investigation for dual fuel mode of operation at 5 deg. bTDC it is found that with the 50% usage of LPG, increases the brake thermal efficiency and volumetric efficiency when compared to gasoline for speed range of 2000 rpm to 4000 rpm. 100% LPG will have much lower CO and HC emissions when compared to gasoline. This is a positive effect on environment. But for other LPGgasoline ratio these emissions going to increases when compared to 100% LPG but it is well below when compared to gasoline for all speeds. NOX emission is more for 100% LPG almost 4 times that of gasoline for all speed conditions. For other LPGgasoline ratio NOX emission is lower. Combustion results revealed that as the LPG percentage increases the peak pressure also increases and it is maximum for 100% LPG for all the speed. This increase in peak pressure will indicate the LPG will give better combustion properties compared to that of gasoline. Compared to peak pressure, the variation in cycle to cycle for IMEP is less for 50% LPG at higher speed conditions. 50% LPG showed better cycle by cycle fluctuations when compared to other fuel conditions. Net heart release rate shows that gasoline will give the more heat release compare to all other fuels, but 100% LPG will release the heat little earlier than gasoline. Since peak pressure is near to TDC for 100% LPG which results in NHRR to occur earlier than gasoline. Final outcome of the research is 100% LPG will have better combustion properties compared to gasoline but cyclic fluctuations are more for 100% LPG.v Results have shown that advancing the static ignition timing will increase the BP by 12 % at 11 deg. bTDC and 7% at 8 deg. bTDC for gasoline. Whereas for 100% LPG increased in BP is 5 % at 11 deg. bTDC and 2% at 8 deg. bTDC. BTE also increased for both gasoline and LPG when advancing static ignition timing because of reduction in the fuel consumption. Also advancing the ignition timing will engine will work leaner side hence reduction in the fuel consumption. From the results it is revealed that as the static ignition timing is advanced volumetric efficiency is increases for gasoline and 100% LPG. For other fuel conditions there is not much effect of static ignition timing on volumetric efficiency. CO emission will drastically reduce when static ignition timing advanced to 8 deg. bTDC after that not significant reduction in CO emission. 100% LPG shown major reduction in CO emission is obtained while advancing the static ignition timing. But advancing the Static ignition timing resulted in increased HC emission for all fuel blends. NOX emission also increases with advancing the static ignition timing for all fuel blends because of increase in the incylinder temperature. Finally after varying the static ignition timing it is found that 8 deg. bTDC with 100% LPG will resulted in better performance and emission characteristics hence these conditions are optimized for the further research work. Using turbocharger performance characteristics are improved. For 100% LPG and gasoline with turbocharger BP and BTE is increased when compared to without turbocharger. BTE obtained is maximum at 8 deg. bTDC with turbocharger for 100% LPG when compared to all other condition. Turbocharged engine fuelled with LPG has higher volumetric efficiency as compared to engine without turbocharger for all speed and load conditions. Volumetric efficiency increases for turbocharged engine because of higher intake air pressure will increase the density of air which leads to increase in the efficiency. When compared to base fuel gasoline at 5 deg. bTDC average increase in volumetric efficiency for 100% LPG with turbocharger is 13% at same condition. Emissions are greatly reduced with turbocharger with 100% LPG when compared to gasoline with turbocharger. When compared to base fuel gasoline at 5 deg. bTDC average decrease in CO emission for LPG with turbocharger is 72% at same condition. There is no much variations in HC emission when compared LPG with and without turbocharger at full load conditions. The turbocharged engine fuelled with LPG, there will be a good decrease in NOX for all load conditions. This is because turbochargervi will increase the charge density hence mixture becomes to lean in the combustion zone hence formation of NOX will reduces for all load conditions. In-cylinder pressure and net heat release rate (NHRR) also greatly improved with usage of turbocharger. Maximum of 17 bar increase in the in-cylinder pressure is obtained with usage of turbocharger. Turbocharged engine gave great improvement in cycle by cycle fluctuations when compared to naturally aspirated engine. Maximum of 84% reduction in COV of IMEP is obtained for turbocharged LPG fuel. Turbocharger will give the better combustion, performance and emission characteristics for LPG fuel. From the experimental results for deionized water-methanol induction system it is observed that as the percentage of water-methanol increases, the engine brake thermal efficiency increased for part and full load conditions. Further increase in the flow rate of water-methanol beyond 30% will reduce the brake thermal efficiency drastically. Also results show that water-methanol induction will results in reduction of brake specific energy consumption (BSEC). Water-methanol induction has good effects in decreasing NOX emission significantly. At full load condition around 30% and 40% average reduction in NOX emission are obtained for 20% and 30% watermethanol flow rate. HC and CO emissions are going to reduce slightly with watermethanol induction due to presence of more oxygen in the charge to the engine. It can be seen that use of 50% LPG is superior alternative for unmodified multi-cylinder SI engine for better engine performance and emission characteristics. The use of 100% LPG is best suited for SI engines at 8 deg. bTDC advance static ignition timing with turbocharging and 20%vaporized water-methanol induction rate to get enhanced engine performance and emission characteristics.