The investigation considers how combustion efficiency and exhaust gas (unburnt hydrocarbon) toxicity are linked to the fundamental flame propagation characteristics (flame propagation velocity and reaction zone width). We present combustion efficiency and unburnt hydrocarbon concentration as functions of fundamental flame propagation characteristics, maximum flame temperature, flame failure temperature and thickness of the unburnt fuel layer adjacent to the combustion chamber walls. Comparing combustion efficiency computed according to the equation proposed to combustion efficiency derived by using an experimentally obtained indicator diagram showed that the data are in good agreement. We studied the connection between unburnt hydrocarbon emission and combustion efficiency. We detected that increasing combustion efficiency leads to lower unburnt hydrocarbon emission, which is explained by reduction of the unburnt fuel ratio in the layer adjacent to the wall. We propose a new technique for calculating unburnt hydrocarbon amount in engine exhaust gases. We show that our technique makes it possible to determine the chemical composition of the air-fuel mixture and the values of flame propagation characteristics that ensure a decrease in unburnt hydrocarbon emission. The results of our study may be used to develop or refine methods of increasing combustion efficiency of composite fuels and reducing exhaust gas toxicity in combustion chambers of internal combustion engines and other power plants.
The prospects using methane-hydrogen fuel in power plants are shown. The effect of turbulence intensity on propagation velocity and width of the zone of chemical reactions methane-hydrogen flame in combustion chamber of variable volume is investigated. The article shows that effect of turbulence intensity on propagation velocity and flame width depends on fuel excess coefficient. During combustion of stoichiometric fuel-air mixtures, an increase in turbulence leads to a more noticeable increase in flame velocity than when burning poor and rich mixtures. It was experimentally found that increase in intensity of turbulence leads to a noticeable change in width of the flame only when burning poor and rich fuel-air mixtures. Processing of the results of foreign and domestic scientists has shown validity of our laws for combustion chambers of different designs using different hydrocarbon fuels. The results of the work can be used in design and debugging of energy-efficient and low-emission combustion chambers.
The article experimentally proves the interconnection of ion current with a carbon concentration in fuel and apparent propagation velocity of the flame. This confirms the hypothesis about the strong influence of rate of radical CH + formation on ion current and allows the use of its amplitude to determine characteristics of flame propagation, which greatly simplifies and reduces the cost of existing research methods using ionization probes of combustion process in piston engines.
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