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In this work, a 7.45 cc capacity glow plug based two-stroke engine for mini aircraft applications was evaluated for its performance, emissions and combustion. It uses a fuel containing 65% methanol, 25% castor oil and 10% nitromethane by volume. Since test rigs are not readily available for such small engines, a reaction type test bed with low friction linear and rolling element bearings was developed and used successfully. The propeller of the engine acted as the load and also the flywheel. Pressure time diagrams were recorded using a small piezoelectric pressure transducer. Tests were conducted at two different throttle positions and at various equivalence ratios. The brake thermal efficiency was generally in the range of 4 to 17.5% depending on the equivalence ratio and throttle position. IMEP was between 2 and 4 bar. It was found that only a part of the castor oil that was supplied participated in the combustion process.

Use of vegetable oils in diesel engines results in increased smoke and reduced brake thermal efficiency. Dual fuel engines can use a wide range of fuels and yet operate with low smoke emissions and high thermal efficiency. In this work, a single cylinder diesel engine was converted to use vegetable oil (Jatropha oil) as the pilot fuel and methanol as the inducted primary fuel. Tests were conducted at 1500 rev/min and full load. Different quantities of methanol and Jatropha oil were used. Results of experiments with diesel as the pilot fuel and methanol as the primary fuel were used for comparison. Brake thermal efficiency increased in the dual fuel mode when both Jatropha oil and diesel were used as pilot fuels. The maximum brake thermal efficiency was 30.6% with Jatropha oil and 32.8% with diesel. Smoke was drastically reduced from 4.4 BSU with pure Jatropha oil operation to 1.6 BSU in the dual fuel mode.

In many Asian countries a significant automobile market share is held by two and three wheelers. Generally, cost and simplicity considerations limit the performance and emission levels of small engines. Methanol is an excellent alternative fuel for SI engines due to its high-octane number, high flame speed, presence of oxygen in its molecule and thus can be used to enhance the performance of small engines. However, use of neat methanol in SI engines poses constraints due to low energy density and poor vaporization characteristics. Also, the effectiveness of methanol as a fuel has still to be thoroughly investigated in small-bore SI engines in order to assess its potential. In this work, a small-bore 200cc three-wheeler automotive engine was modified to operate in the port fuel injection mode with neat methanol as the fuel.

In this work methanol was port injected while diesel was injected using a common rail system in a single cylinder non-road CI engine. Experiments were conducted with single (SPI) and double (DPI - pilot and main) injection of the directly injected diesel at 75% load and at a constant speed of 1500 rpm. The effects of methanol to diesel energy share (MDES) and injection scheduling on combustion stability, efficiency and emissions were evaluated. Initially, in the SPI mode, the methanol to diesel Energy Share (MDES) was varied, while the injection timing of diesel was always fixed for best brake thermal efficiency (BTE). Increase in the MDES resulted in a reduction in NOx and smoke emissions because of the high latent heat of vaporization of methanol and the oxygen available. Enhanced premixed combustion led to a raise in brake thermal efficiency (BTE). Coefficient of variation of IMEP, peak pressure and BTE were deteriorated which limited the usable MDES to 43%.

The property of methanol to surface ignite can be exploited to use it in a diesel engine even though its cetane number is very low. Poor lubricity of methanol is still an issue and special additives are needed in order to safeguard the injection system components. In this work a common rail three cylinder, turbocharged diesel engine was run in the glow plug based hot surface ignition mode under different injection strategies with methanol as the main fuel in a blend with n-butanol. n-Butanol was used mainly to enhance the viscosity and lubricity of the blend. The focus was on the effect of different injection strategies. Initially three blends with methanol to n-butanol mass ratios of 60:40, 70:30 and 80:20 were evaluated experimentally with single pulse fuel injection. Subsequently the selected blend of 70:30 was injected as two pulses (with almost equal mass shares) with the gap between them and their timing being varied.

Methanol has a very low cetane number but it can be used in the neat form in a glow plug based hot surface ignition (HSI) engine at CI engine compression ratios. A CFD simulation model of a glow plug assisted methanol HSI engine was developed and validated using experimental data reported in literature. A study on the effect of single and multipulse injection of methanol, glow plug surface temperature, injection pressure and effect of shielding it were conducted by applying the model on to a three cylinder neat methanol HSI engine. A glow surface temperature of 1273 K was found to be sufficient for ignition of methanol at 50% load while the distance between the glow plug and the injector affected the ignition delay. The sprays were ignited sequentially starting from the one closest the glow plug which resulted in extended combustion. Injecting methanol in double pulses reduced the Maximum Rate of Pressure Rise (MRPR).