A plasmachemical method of cleaning the exhaust gases of Diesel engines from toxic components in a ferroelectric packed-bed reactor is described. Special features of the electric circuit of this plasmachemical system and the energy efficiency of the process of cleaning under the conditions of pulse-periodic input of energy to the discharge are considered.
621.436Problems in the use of plasma reforming of Diesel fuel for reduction of the toxicity of exhaust gases are considered. Results of experiments on the decomposition of Diesel fuel in nonequilibrium plasma of a spark discharge are given. It is shown that under these conditions the content of hydrogen in the obtained synthesis gas can reach 10% or more.The widespread use of internal-combustion engines in different spheres of human activity has had serious ecological impacts, related mainly to pollution of the environment by toxic components of the exhaust gases (EG) of automotive engineering. In parallel with the known methods for reduction of the toxicity of exhaust gases (catalytic cleaning, electric-discharge plasma systems) [1], a method using a hydrogen-enriched gas mixture obtained by decomposition of a part of the Diesel fuel in the discharge [2] is promising.A compact plasmatron that runs off an on-board power source can be used to convert a part of the fuel to a hydrogen-containing gas mixture for both direct injection to the combustion chamber and treatment of EG in the plasmachemical reactor or catalyst. The presence of hydrogen in the fuel mixture can lead to more complete burning of fuel at a smaller effective temperature and the corresponding decrease of soot and carbon and nitrogen oxides in EG. Plasma increases the partial oxidation reaction that converts hydrocarbons of the fuel to the hydrogen-enriched gas mixture (the oxygen/carbon ratio is unity, exothermal reaction):For Diesel fuel the reaction occurs with liberation of about 10-15% of the energy:C 14 H 26 + 7O 2 → 14CO + 13H 2 . Figure 1 gives a basic diagram of the use of an on-board plasmatron-reformer of fuel with direct injection of a hydrogen-enriched synthesis gas to the engine. The effect of the operation according to this scheme is a reduction of the concentrations of NO x , hydrocarbons, and soot particles, and improvement of the thermal efficiency of the engine.We estimate the amount of hydrogen necessary for the case where partial replacement of the Diesel fuel by hydrogen does not considerably change the operating conditions of the engine but decreases the emission of toxic components. On the basis of experiments [3], we admit substitution of 10% of the Diesel fuel by hydrogen. Fuel consumption for a typical engine is ,100 g/min. Since the heat power of hydrogen is almost threefold higher than the heat power of the Diesel fuel, 3 g of hydrogen are enough to substitute 10 g of the Diesel fuel. In this case, the molar concentration of hydrogen will be more than 50%, which guarantees stable operation of the engine with very lean mixtures. The maximum pressure of combustion of these mixtures increases slightly.Modern plasmatrons have a high efficiency (higher than 80%). A specific efficiency of a typical plasmatron is 1 g/h of conversion products at an electric power consumption of 1 W. The power consumption necessary for production of 3 g/min of hydrogen is ,200 W.Introduction of hydrocarbon (ethylene, propane, methane) additives ...
537.525The results of the experimental studies of a full-scale plasmachemical system for lowering the toxicity of exhaust gases of the D-243 diesel engine are presented. It has been shown that under nominal operating conditions of the D-243 engine the device decreases the content of soot by more than 95% and lowers the concentration of nitrogen oxides by 24% under combined conditions of discharge power supply and at a value of the specific energy input up to 2.5 W⋅h/m 3 .One of the main directions in increasing the ecological indices of modern automobiles and tractors is the application of a complex of measures for additional physicochemical cleaning of exhaust gases from toxic components in the process of discharge. These measures are realized in practice by using special gas cleaners installed in the discharge system. Of the known gas-cleaning techniques, the most promising for mobile machinery equipped with internal combustion engines is the use of electric discharge systems for lowering the toxicity of exhaust gases that are capable, at moderate energy inputs, of providing a high degree of cleaning gas flows from both aerosol particles and toxic gaseous components without using the expensive materials (platinum, palladium) used in catalytic cleaners.The volt-ampere characteristics of the electrode system of the plasmachemical reactor for the D-243 engine at various temperatures of the flow of exhaust gases are given in Fig. 1.Consider the results of experimental studies of the operating efficiency of the plasmachemical system [1-3] depending on the value of the voltage powering the reactor and the energy input into the discharge for different operating conditions of the engine (Fig. 2). The obtained characteristics permit establishing a relation between the value of the voltage powering the reactor and the degree of cleaning exhaust gases as well as determining the highest possible degree of cleaning the exhaust gases of the D-243 diesel by the proposed electric discharge system depending, in the first place, on its constructional arrangement and the concentration of soot in the exhaust gases of the diesel.At some critical voltage (6.5-8 kV) on the electrode system of cleaning gases from soot, the soot content does not decrease at all or decreases insignificantly (by 1-2%). As the voltage on the electrode system is increased, the content of soot in the exhaust gases begins to decrease monotonically. At a voltage exceeding 14-15 kV, the reactor goes to the saturation regime. Further increase in the voltage is pointless because, in so doing, the specific energy input markedly increases with a small additional value of the degree of cleaning. An increase in the discharge powering voltage from 15 to 17 kV for the nominal discharge of gases leads to an increase in the power approximately from 320 to 520 W (by a factor of 1.6), while the degree of cleaning increases approximately from 92 to 95%. Obviously, to obtain a higher degree of cleaning with a moderate specific energy input into the discharge (up to 0.5 W⋅h/...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.