Current Issue : April - June Volume : 2017 Issue Number : 2 Articles : 6 Articles
Based on the chemical reaction mechanism of fuel combustion, NO...
The effect of the fuel injection ratio on the combustion and emission characteristics of\nstratified lean mixture combustion was investigated for a spray-guided liquefied petroleum gas\n(LPG) direct injection engine. Inter-injection spark-ignition combustionââ?¬â?a specially designed\ncombustion strategy for LPG fuel derived from a two-staged injectionââ?¬â?was employed to maximize\nthe improvement in thermal efficiency when combustion stability is secured. When changing the fuel\ninjection ratio, the optimum spark advance and fuel injection timings were experimentally determined\nto maximize the thermal efficiency based on sweeping timings. The optimum fuel injection ratio with\nthe highest thermal efficiency (42.76%) and stable operation was 60%/40%, with the optimization\nof the spark advance and fuel injection timing, because of the locally rich mixture region in the\nrecirculation zone. NOx emissions were at their highest level with a fuel injection ratio of 60%/40%\nbecause of the high combustion temperature, and the levels of total hydrocarbon and CO emissions\nwith 50%/50% and 60%/40% fuel injection ratios were similar, whereas emissions at 70%/30% were\nsignificantly higher because of fuel wetting and the formation of over-lean mixture....
This article describes the configuration and working principle of the high-temperature combustion system; according to\nthe control requirements which have a wide range and high precision for fuel flow-rate of the high-temperature combustion\nsystem, a set of fuel supply system is designed based on the frequency conversion hydraulic technology and electrohydraulic\nproportional technique. An automatic control system with the function of field and remote control is carried\nout to achieve the precise supply of the fuel. The transfer function which describes the dynamic characteristic of the fuel\nsupply system is given and the dynamic matrix control algorithm is employed to realize the high-quality control of fuel\nflow-rate. The experimental results show that the response time of flow-rate is about 12 s, almost no overshoot, and\ncontrol accuracy within 1%. Therefore, the designed fuel supply system can meet the requirements of the high temperature\ncombustion system, and the designed control system has good control performance....
A single layer filtration system was developed to investigate the filtration and regeneration performance of diesel particle filter\n(DPF). The particle layer thickness was directly measured online to analyze the different filtration stages. The influence of particle\nproperty on particle layer stage performance was also investigated. The results indicate that the filtration velocity can greatly affect\nthe deep bed filtration stage, and the deposited particle layer can be compressed even in very low filtration velocity and higher\nfiltration velocity trends to form denser particle layer. Optimizing the pore structure can effectively shorten the deep bed filtration\nstage and reduce the pressure drop eventually. An empirical function was proposed to relate the pore structure and the initial\nincrement rate of pressure drop, which presented that reducing the pore size distribution range (3...
Current portable power generators are mainly based on internal combustion engine\nsince they present higher values of efficiency comparing to other engines; the main\nreason why internal combustion engine is not convenient for micro power generation\n(5 - 30 kW) is because of their heaviness. Micro and ultra micro gas turbine devices,\nbased on a micro compressor and a micro turbine installed on the same shaft,\nare more suitable for this scope for several reasons. Micro turbine systems have many\nadvantages over reciprocating engine generators, such as higher power density (with\nrespect to size and weight), extremely low emissions and few, or just one, moving\npart. Those designed with foil bearings and air-cooling operate without oil, coolants\nor other hazardous materials. Micro turbines also have the advantage of having the\nmajority of their waste heat contained in their relatively high temperature exhaust.\nMicro turbines offer several potential advantages compared to other technologies for\nsmall-scale power generation, including: a small number of moving parts, compact\nsize, lightweight, greater efficiency, lower emissions, lower electricity costs, and opportunities\nto utilize waste fuels. The object of this study is the experimental tests on\na stand-alone gas turbine device with a pre-heated combustion chamber (CC), to validate\nthe fuel consumption reduction, compared to an actual and commercial device,\nused on air models....
Themolecular structure of mixed hydrous and anhydrous ethanol with up to 10% v n-heptane had been studied.The burning velocity\nwas examined in a cylindrical explosion combustion chamber.The result showed that the burning velocity of hydrous ethanol\nis higher than anhydrous ethanol and n-heptane at stoichiometric, rich, and very rich mixtures. The burning velocity of hydrous\nethanol with n-heptane drops drastically compared to the burning velocity of anhydrous ethanol with n-heptane. It is caused by two\nreasons. Firstly, there was a composition change of azeotropic hydrous ethanol molecules within the mixture of fuel. Secondly, at\nthe same volume the number of ethanol molecules in hydrous ethanol was less than in anhydrous ethanol at the same composition\nof the n-heptane in the mixture. At the mixture of anhydrous ethanol with n-heptane, the burning velocity decreases proportionally\nto the addition of the n-heptane composition.The burning velocity is between the velocities of anhydrous ethanol and n-heptane.\nIt shows that the burning velocity of anhydrous ethanol mixed with n-heptane is only influenced by the mixture composition....
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