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The test was done on cars travelling at speeds of 20㎞/h, 60㎞/h and 100㎞/h, the performance testing mode for chassis dynamometer. In this test, the secondary waveform were measured, including those using faulty MAP sensors, oxygen sensors and spark plugs. The results from these measurements and their analysis of secondarywaveform can be summarized as follows: 1) The secondary waveform measured from the faulty oxygen sensor showed a lot of noise around peak voltage and in the rising and falling sections during spark line which means that the air fuel mixture was non-homogeneous. 2) The secondary waveform from the faulty MAP sensor showed the worst shape compared to other sensors, including variation of spark line, state of air-fuel mixture and velocity of flame front. 3) The spark line time of secondary waveform using a faulty spark plug displayed the shortest and smallest energy spark line, which means that a misfire occurred.
In this study, a spark ignition engine operated with LPG and DME blended fuel was studied experimentally. Performance and emissions characteristics of a LPG engine fuelled by LPG and DME blended fuel were examined. Results showed that stable engine operation was possible for a wide range of engine loads within 20% mass content of DME fuel. Also, engine output power within 10% mass content of DME fuel was comparable to pure LPG fuel operation. Exhaust emissions measurements showed that hydrocarbon and NOx were increased with the blended fuel at low engine speed. Engine output power was decreased and break specific fuel consumption (BSFC) was severely increased with the blended fuel since the energy content of DME was much lower than that of LPG. Considering the results of engine output power and exhaust emissions, the blended fuel within 20% mass content of DME could be used as an alternative fuel for LPG.
Combustion and emission characteristics of LPG(Liquefied Petroleum Gas) and gasoline fuels were compared in a single cylinder engine with direct fuel injection. While fuel injection pressure and IMEP(indicated mean effective pressure) were varied with 60, 90, 120 bar and 2 to 10 bar, another parameters for the engine operation as engine speed, air excess, and fuel injection timing were fixed at 1500 rpm, 1.0, and BTDC 300 CA respectively. Experimental results show that MBT timing for LPG is less sensitive to IMEP, and its combustion stablility(COVIMEP) is also better than gasoline fuel. However, LPG is found that thermal efficiency has lower values a little due to increase of pumping loss by higher throttling inherently. Gasoline shows longer burn durations in the early stage of combustion(10% MBF), but when considering total burn duration(90% MBF) gasoline was shorter than LPG for over IMEP 7 bar. Hydrocarbon emissions of gasoline rise to a level of three-fold than those of LPG. In addition, nitric oxides has higher values for gasoline but carbon monoxide for both fuels shows similar level for all test conditions
Recently, many researches on alternative fuels were carried out due to increasing needs for lower fuel consumption rate and exhaust emissions. Among these fuels, DME has known as clean energy because of lower NOx compared with gasoline and diesel. However, rubber and plastic are dissolved or swelled easily in DME compared with LPG. Therefore, with seals made from these materials, careful attention is needed when using them with DME. In this study, to find the best seal materials with the tolerance for both LPG and DME, chemical reaction of seal materials was tested through immersion test and tensile test with the LPG-DME blended fuel. Also, chemical analysis was conducted about the residues occurred in immersion test. The results of tensile stress test showed the maximum stress and extensional strain was decreased at 60 to 70%. Through the chemical analysis, it was known that main ingredient of residue was Phthalic acid.
In this study, combustion and emission characteristics were investigated for both direct injection and port fuel injection in an LPG single cylinder spark ignition engine. The engine was operated over three different loads (2, 6, 10 bar of indicated mean effective pressure), fuel injection pressures(60, 90, 120 bar for DI, 7 bar for PFI), and air excess ratio(λ=1) at 2000 rpm. For IMEP DI type were more sensitive to fuel injection timing than PFI and showed higher thermal efficiency than that of PFI type except for 2 bar IMEP. The emission characteristics of DI type were also compared with PFI type. Hydrocarbon emission for DI type was approximately 10% lower than that of PFI type. Nitric oxides emission for both types was increased as the load increases. In addition, carbon monoxide emission for DI type was slightly decreased as the load increases.
In this study, LPG-blended DME fuel was experimentally investigated in CI(compression ignition) engine. In particular, performance, emissions characteristics (including hydrocarbon, CO, and NOx emissions), and combustion stability of engine fueled with LPG-blended DME fuel were examined. The extent of LPG fuel in the blended fuel was 0-40 wt%. Results showed that stable engine operation was possible in a wide range of engine loads on DME blended with maximum 30% of LPG by mass in a CI engine. Considering the results of the engine power output and exhaust emissions, blended fuel up to 30% of LPG by mass can be used as an alternative to diesel in a CI engine. LPG blended DME fuel is expected to have potential for enlarging the DME market.
In this study, the numbers, sizes of particles from a single cylinder direct injection spark-ignition (DISI) engine fuelled with gasoline and LPG are examined over a wide range of engine operating conditions. Tests are conducted with various engine loads (2~10bar of IMEP) and fuel injection pressures (60, 90, and 120 bar) at the engine speed of 1,500 rpm. Particles are sampled directly from the exhaust pipe using rotating disk thermodiluter. The size distributions are measured using a scanning mobility particle sizer (SMPS) and the particle number concentrations are measured using a condensation particle counter (CPC). The results show that maximum brake torque (MBT) timing for LPG fuel is less sensitive to engine load and its combustion stability is also better than that for gasoline fuel. The total particle number concentration for LPG was lower by a factor of 100 compared to the results of gasoline emission due to the good vaporization characteristic of LPG. Test result presents that LPG for direct injection spark ignition engine help the particle emission level to reduce.