Experimental Studies on Magnetic Field Assisted Combustion of Hydrocarbon Fuels in a Multicylinder Spark Ignition Engine under Liquid Phase and Gas Phase Operation

Abstract

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.