Excess Air Factor Research Articles

Use of Chemi-Ionization to Calculate Temperature of Hydrocarbon Flame

In the present paper, we have experimentally studied the dependences of the maximum temperature of the hydrocarbon flame on the electron current (due to the flame chemi-ionization), the width of the turbulent combustion zone, and the amount and composition of the air-fuel mixture in the combustion chamber of variable volume. Based on the proposed formula, we have been also able to estimate the temperature and compare with its experimental value showing that the convergence has been more than 85% at an excess air factor value ranging from 0.8 to 1.15. The obtained results can be used to predict and monitor the maximum flame temperature in the combustion chamber of an internal combustion engine and other power plants by using the ionization probe.

DEVELOPMENT OF THE DESIGN SCHEME OF THE COMBUSTION CHAMBER FOR BURNING OF WOOD CHIPS THE OLD SLEEPERS

А calculation scheme for the utilization of chips of old wooden sleepers in a vortex furnace is proposed. The vortex furnace provides two zones of reaction of a combustible substance with air: the primary zone is the gasification of old sleepers and the afterburning of the solid residue with a lack of air oxygen, the secondary zone is the burning of the gas phase. The initial data for the thermodynamic calculation is given. The results of the equilibrium calculation of the thermal decomposition of wood on the grate and the combustion of gasification products are presented for different values of the excess air factor, as well as some experimental data. A comparison of the calculation results with the experimental data is carried out.

Experimental Study of the Temperature Rise in the Frontal Layer of a Structured Porous Metal Catalyst in Air Conversion of Methane

Heat-resistant Ni/MgO block catalysts have been developed on porous nickel carriers for the air conversion of natural gas to synthesis gas. The catalysts were tested under normal pressure, which allowed one to select of a number of samples that demonstrate relatively the low temperature of the frontal layer of the catalytic block of 880–940°C at the inlet temperature of the mixture of 20°C and excess air factor of 0.3. The composition of the mixture at the outlet remained close to thermodynamic equilibrium at a volumetric flow rate of up to 49 000 h–1. It was experimentally established that the temperature of the frontal layer decreases with increasing pressure (2–6 atm), an increase in the frontal layer temperature with an increasing coefficient of excess air (0.31–0.42) and the rate of the inlet mixture (0.30–0.74 m/s). This made it possible to obtain approximate estimates of the areas of exothermic and endothermic reaction stages taking into account external diffusion inhibition based on the analysis of the heat balance equation for the frontal layer of the catalyst.

ЗАБРУДНЕННЯ ПОВЕРХОНЬ НАГРІВУ УТИЛІЗАЦІЙНИХ КОТЛІВ ПРИ СПАЛЮВАННІ ВОДОПАЛИВНИХ ЕМУЛЬСІЙ НА ОСНОВІ МАЛОВ’ЯЗКИХ ПАЛИВ

The analysis of literature data, which showed a decrease fuel consumption and smoke emissions of diesel engines during the combustion of water-fuel emulsions based on diesel fuel, was carried out.The combustion of water- fuel emulsions decreases the intensity of low-temperature pollution, which is explained by significant improvement in the quality of the combustion process as a result of micro explosions emulsion droplets and an increase in the contact surface of fuel vapor with the oxidizer.According to the literature data, the use of water-fuel emulsion does not require constructive alterations of the diesel engine and can significantly improve the environmental characteristics of the engine. Based on the experimental and theoretical studies, the relations of the specific increase in the mass of pollution on the excess air factor for different water content of water-fuel emulsion based on low-viscosity fuels were obtained. For evaluation of the joint effect of three factors on the pollution intensity in the statistical processing of experimental data, the Statgraphics Plus for Windows system, providing access to a full set of statistical methods and providing an opportunity to conduct an extended regression analysis was used. Statistical processing of the research results, which showed the prevailing influence on the specific increase in the mass of pollution of the sulfur and water content in the water-fuel emulsion, and then the excess air factor, was carried out. A three-dimensional model and regression equations that take into account the effect on the value of the specific increase in the mass of pollution of the main parameters are obtained. The contour graphs of the dependences of the specific increase in the mass of pollution on the sulfur content, water content in the water-fuel emulsion and the excess air factor are obtained. Analysis of the research results shows that burning of water-fuel emulsions based on low-viscosity fuels with water content of 30% reduces the level of pollution of heating surfaces by 2,36 times. The obtained relations can be used in the design of condensing heating surfaces

Modeling of the Heat Exchange Process in the Cylinder of Diesel between the Fuel Circuit and the Air Charge

Studies of the process of atomization of fuel by injectors of ICE showed [1,2] that oxygen and fuel in the jet are distributed unevenly. The value of the excess air factor in the fuel flare decreases from 0.8-0.9 on its surface [3] to 0.15-0.25 at its center [4], and the droplet sizes increase from a few microns to 0.1mm and more. The maximum diameter of the fuel droplets corresponds to the diameter of the nozzle nozzles of the injector [5].

Result of implementation of resource-saving system in agro-industrial complex

The object of research is the result of the introduction of resource saving in the agro-industrial complex (AIC), in particular in the first area – machine building for agriculture. One of the most problematic places is the systematic implementation of resource-saving in the agro-industrial complex. To overcome this problem, the authors propose a scheme for selecting a resource-saving project for the maintenance of the agro-industrial complex in order to assess the effectiveness of resource-saving technologies. The aim of the authors is analyze the effectiveness of implementing resource-saving measures in the complex of the first sphere of the agro-industrial complex. To detail the aim, a task was set to approbate a scheme for selecting a resource-saving project for the maintenance of the agro-industrial complex for analyzing resource efficiency in enterprises, and determining the effectiveness of resource-saving measures. As a result, the multi-criteria rationale for increasing the resource efficiency of agribusiness enterprises is assessed as such, which is adequate for assessing the efficiency of production and the level of resource saving. The technology of fuel-air mixture optimization, optimally depleted fuel-air mixture with an excess air factor a≥1 . 1 – 1 . 15 ensures the operation of the gasoline engine with the minimum content of harmful components in the exhaust gases. In particular, the NO x concentration is significantly lower than when the mixture is mixed with a stoichiometric mixture. The economic efficiency of the resource-saving technology of the sowing device with the reserve dosing device is calculated. The average annual increase in profit from the introduction of a modernized precision seeding machine for the main tilled crops (corn, sunflower, soybeans, beets) is 1216.45 c. u. on sowing one hectare. The total annual income for a seed drill for the year is 956 thousand c.u. On the example of sowing one of the crops, maize yields the greatest economic effect – 1600,000 in a year, the smallest – sunflower (266 thousand c. u.). At the same time, the best prototype shows itself when soybean was sown, reducing losses by 99 % in value terms.

Relation between flame chemiionization and variable-volume combustion chamber temperature and pressure

The article presents the results of investigating the relation between flame chemiionization and the flame temperature and pressure in a variable- volume combustion chamber. Functional dependences of flame temperature and maximum pressure on the electron current caused by flame chemiionization, fundamental characteristics of flame propagation and combustion efficiency are presented. Comparison of the temperature calculated by the proposed method with experimental data shows that with the excess air factor of 0.8 to 1.15, the precision is more than 85%. Comparison of the maximum pressure obtained experimentally and calculated by the refined Vibe model, using the proposed formulas, showed good agreement. The results of the work can be used to predict and monitor maximum flame temperature and pressure in the combustion chamber of an internal combustion engine and other power plants using an ionization probe.

Concept of Heat Recovery from Exhaust Gases

The theme of the article is to determine the possibility of waste heat recovery and use it to prepare hot water. The scope includes a description of the existing sample of coal-fired boiler plant, the analysis of working condition and heat recovery proposals. For this purpose, a series of calculations necessary to identify the energy effect of exhaust temperature decreasing and transferring recovery heat to hot water processing. Heat recover solutions from the exhaust gases channel between boiler and chimney section were proposed. Estimation for the cost-effectiveness of such a solution was made. All calculations and analysis were performed for typical Polish conditions, for coal-fired boiler plant. Typicality of this solution is manifested by the volatility of the load during the year, due to distribution of heat for heating and hot water, determining the load variation during the day. Analysed system of three boilers in case of load variation allows to operational flexibility and adaptation of the boilers load to the current heat demand. This adaptation requires changes in the operating conditions of boilers and in particular assurance of properly conditions for the combustion of fuel. These conditions have an impact on the existing thermal loss and the overall efficiency of the boiler plant. On the boiler plant efficiency affects particularly exhaust gas temperature and the excess air factor. Increasing the efficiency of boilers plant is possible to reach by following actions: limiting the excess air factor in coal combustion process in boilers and using an additional heat exchanger in the exhaust gas channel outside of boilers (economizer) intended to preheat the hot water.

ОСОБЕННОСТИ РАБОТЫ ДИЗЕЛЯ НА РЫЖИКО-МИНЕРАЛЬНОМ ТОПЛИВЕ В РЕЖИМЕ САМОСТОЯТЕЛЬНОГО ХОЛОСТОГО ХОДА

The mode of independent idling, characterized by an impaired process flow, unproductive fuel consumption and increased emissions of harmful substances into the atmosphere, is the most unfavorable mode of the diesel engine operation. Therefore, the aim of the research is to reveal the peculiarities of the tractor diesel engine operation by the camelina-mineral fuel in the mode of independent idling. Camelina-mineral fuel is a mixture of camelina oil and mineral diesel fuel in certain ratio of these components. To assess the possibility of using the camelina oil as biological component of diesel mixed fuel, an experimental study of the D-243 diesel engine in idling mode was carried out, and the degree of influence of the different ratio of the components of the mixed fuel on its parameters was determined. The researches were carried out with the diesel fuel on the L-0.2-62 mineral fuel and the camelina-mineral fuel with a ratio of the biological and mineral components: 25% RyzhM + 75% DT; 50% RyzhM + 50% DT; 75% RyzhM + 25% DT; 90% RyzhM + 10% DT and 90% RyzhM + 10% DT (US). For the parameters of the diesel, the excess air factor, the filling ratio of the diesel cylinder with fresh charge, the maximum cycle pressure, the hourly fuel consumption, smoke and carbon monoxide content in the exhaust gases are taken. It is established that when the diesel engine works on camelina-mineral fuel mode the minimum sustainable speed of the crankshaft idle speed 800 min-1 the values of maximum cycle pressure (6.3 MPa) and the filling ratio of the cylinders of a diesel engine the fresh charge (0,87) remain unchanged. The coefficient of excess air, increasing in mixed fuel shares of camelina oil to 90%, reduced from 7.187 to 4.619, while fuel consumption increases of 1.1 kg/h 2 kg/h. The best environmental indicators are observed when working on red-and-mineral fuel 50% RyzhM + 50% DT. Handling mixed fuel with ultrasound reduces fuel consumption, smoke and content of carbon oxide in the exhaust gas relative to the mixed fuel not treated with ultrasound.

Ignition of poor fuel-air mixtures in gasoline-driven ICEs - problems, solutions

The article deals with the development of technologies in the field of improving the organization of the combustion process in internal combustion engines in order to solve the problem of protecting the environment and increasing the efficiency of fuel resources. The carried out analysis has shown the increased interest of researchers and automotive experts in the problem of ignition of poor mixtures in ICE by the method of fuel-air charge separation in the combustion chamber. The directions of intensification of combustion of poor mixtures in internal combustion engines are considered due to application of various methods of fuel-air charge separation in the combustion chamber of internal combustion engines. Combustion of poor mixtures ensures low emissions of harmful substances with exhaust gases of the internal combustion engine and improved fuel economy. The advantage of an internal combustion engine using poor fuel-air mixtures is its operation with little or no charge throttling at the inlet. At the same time, fuel consumption and, correspondingly, CO2 emissions are reduced to 25%. Low concentrations of harmful emissions also reduce the efficiency requirements of the neutralizer. The process of combustion of poor mixtures is carried out due to the technologies of direct electronic fuel injection into the combustion chamber under high pressure and catalytic neutralization of combustion products of poor mixtures. Effective combustion of fuel-air mixtures is achieved with an excess air factor of less than 1.7. The article also contains the results of tests of the prechamber-flare internal combustion engine, which showed the possibility of using qualitative engine power regulation due to work on poor mixtures and a significant reduction in emissions of harmful substances with exhaust gases. It is shown that the use of an electronic ignition system with an increased discharge energy and a system of homogeneous mixture formation leads to an intensification of combustion of poor mixtures in the internal combustion engine, and allows the engine to operate at superhigh mixtures with an air excess factor of 3.5 with stable combustion of fuel-air mixtures.

EFFECT OF COMPOSITION OF FUEL CONTAINING BUTANOL ON WORKING PROCESS PARAMETERS OF DIESEL ENGINE

Computational researches the effect of composition of fuel containing butanol on working process parameters of 4ЧН 11/12,5 diesel engine on the external speed characteristic have been conducted. Nominal power is 140 kW at engine speed 2300 min–1. The engine is equipped with gas turbine pressure charging with intercooling of charging air, accumulator-type fuel-handling system. Calculations of the working process have been made in accordance with the developed computer program and models. Investigations have been carried out in two stages: without any changes in regulation of fuel-handling system and with cyclic fuel delivery that ensure such value of excess air factor at various operational modes which corresponds to the operation with diesel fuel. All the obtained results have been analyzed in the paper. The paper shows changes in mean indicated pressure, specific indicated fuel consumption, indicated efficiency, specific nitrogen oxides emissions for various modes in question while using 5, 10, 15, 20, 25 and 30 % mixture of diesel fuel with butanol. Dependences of parameters pertaining to diesel operation have been determined according to external speed characteristic for various mixtures and the obtained data make it possible to justify parameters of the fuel-handling system. It has been recommended to use a diesel fuel-butanol mixture containing 15 % of butanol without any changes in regulating and design engine parameters. It has been revealed that in order to improve parameters of the engine operational process mixture composition must be changed while changing the operational mode. An injector nozzle with a compound needle for the fuel-handling system has been developed and it allows to change fuel composition according to engine operational mode.

Prediction of Excess Air Factor in Automatic Feed Coal Burners by Processing of Flame Images

In this study, the relationship between the visual information gathered from the flame images and the excess air factor λ in coal burners is investigated. In conventional coal burners the excess air factor λ. can be obtained using very expensive air measurement instruments. The proposed method to predict λ for a specific time in the coal burners consists of three distinct and consecutive stages; a) online flame images acquisition using a CCD camera, b) extraction meaningful information (flame intensity and brightness)from flame images, and c) learning these information (image features) with ANNs and estimate λ. Six different feature extraction methods have been used: CDF of Blue Channel, Co-Occurrence Matrix, L ∞-Frobenius Norms, Radiant Energy Signal (RES), PCA and Wavelet. When compared prediction results, it has seen that the use of co-occurrence matrix with ANNs has the best performance (RMSE = 0.07) in terms of accuracy. The results show that the proposed predicting system using flame images can be preferred instead of using expensive devices to measure excess air factor in during combustion.

Experimental Study on Treating Waste Printed Circuit Boards by Molten Salt Oxidation

The waste management of e-wastes is a significant challenge, especially for the disposal of waste printed circuit boards (WPCBs). An effective, economic and environmental-kind recycling technology is in great demand. Molten salt oxidation (MSO) is a robust thermal process, has the inherent capability of destroying organic constituents of wastes while retaining the inorganic constituents in the molten salt. In the present study MSO is employed for the disposal of waste printed circuit boards aimed at describing the treating method of WPCBs using MSO, and evaluating the efficiency of this alternative. Molten salt oxidation experiments of WPCBs have been conducted in a lab-scale molten salt reactor using a ternary carbonate salt (Li, Na, K)2CO3. The operation parameters investigated are the temperature of molten salts, the excess air factor and the residence time of the reactants in the salt bath. Results show that the retention efficiency of bromine is higher than 99.9%, irrespective of the operating conditions. The emissions of CO and SO2 decrease with temperature increasing, while the emission of NOx first decreases and later increases. And when the residence time is lengthened, the emissions of CO, NOx and SO2 decrease. Compared to the temperature and the residence time’s role, the effect of excess air factor on the emissions of CO, NOx and SO2 is relatively small. Over 95% of the copper in WPCBs are recycled. The fibreglass that is the main component of the ash content is dissolved by the molten carbonates and retains in the salt bath. The results of the present study show molten salt oxidation is an environmentally friendly and effective alternative technology for the disposal of WPCBs.

两种生物质燃料锅炉能效测试对比分析

分别对型号为DZL4-1.25-BMF以及DZG4-1.25-BMF的生物质颗粒锅炉进行能效测试，并对其进行正反平衡测试的结果进行分析。测试结果表示型号为DZL4-1.25-BMF的链条炉锅炉热效率(78.75%)相比型号为DZG4-1.25-BMF的固定炉排锅炉(70.10%)具有更高的热效率。在燃烧参数分析下发现，固定炉排锅炉在燃烧中存在排烟中一氧化碳含量过高，氧气量供应不足的情况；而链条炉排在燃烧过程中虽然有过量空气系数过高的情况出现，但相比固定炉排锅炉，改善了燃烧状况，降低了气体未完全燃烧损失。就型号为DZL4-1.25-BMF的锅炉能效测试数据情况而言，建议在运行过程中适当调节鼓引风量，降低过量空气系数，减少排烟损失，有利于提高锅炉热效率。 Thermal efficiencies of Biomass fuel boilers of model DZG4-1.25-BMF and model DZL4-1.25-BMF were tested, respectively. Both of the thermal efficiencies were analyzed by methods of positive balance and counter balance. It was resulted that thermal efficiency of model DZL4-1.25-BMF (78.75%) was higher than the model DZG4-1.25-BMF (70.10%). According to the experimental data, an overhigh content of carbon monoxide in the exhaust gas was found in the model DZG4-1.25-BMF as shortage of oxygen occurred in the flame. But lower gas incomplete combustion loss was found in model DZL4-1.25-BMF though it performed a higher excess air factor during the test. It is suggested that it needs methods to decrease the excess air factor in order to increase the thermal efficiency of model DZL4-1.25-BMF.

Thermal Protection of Internal Combustion Engines Pistons

The research aiming to improve the reliability and durability of internal combustion engines (ICE) has traditionally been relevant. Today, the use of ceramic materials and coatings in engine manufacturing is an increasingly frequent research subject. The most promising method to form such coatings on aluminum-alloy pistons is microarc oxidation (MAO). The goal of this research is to study the efficiency of thermal protection provided by a MAO layer on the piston head experimentally. To determine the optimum coating thickness, we have simulated the thermal state of the piston using ANSYS Multiphysics. Then we carried out motor tests of the pistons using the single-cylinder unit of a four-cylinder two-stroke engine. The coating was applied to the surface of the piston head on the combustion chamber side. We tested the pistons with MAO coating thicknesses of 76 and 106 μm. The piston temperature was measured on the piston head surface on the crankcase side using temperature indicators. The tests were carried out under excess air factor α=0.95 at the full-load curve. As a result, we have elicited the positive effect of MAO coating applied to the piston head. Per calculation and test results, such coating reduced the temperature of the piston by 45...78 °C. The thickness of the MAO layer was not found to have any significant impact on the thermal state of the piston. The research results are applicable in engine manufacturing when designing new engines or upgrading the existing engines to make them more reliable.

Efficiency of utilization of heat of moisture from exhaust gases of heat HRSG of CCGT

The paper discusses the technology of utilizing the heat of exhaust gas moisture from heat recovery steam gases (HRSG) of combined-cycle gas turbine (CCGT). Particular attention focused on the influence of the excess air factor on the trapping of the moisture of the exhaust gases, as in the HRSG of the CCGT its value varies over a wider range than in the steam boilers of the TPP. For the research, has been developed a mathematical model that allows to determine the volumes of combustion products and the amount of water vapor produced according to a given composition of the burned gas and determine the amount of moisture that will be obtained as a result of condensation at a given temperature of the flue gases at the outlet of the condensation heat exchanger (CHE). To calculate the efficiency of the HRSG taking into account the heat of condensation of moisture in the CHE an equation is derived.

ВЛИЯНИЕ КОЭФФИЦИЕНТА ИЗБЫТКА ВОЗДУХА НА РАСХОД ТОПЛИВА ДИЗЕЛЬНЫМИ ДВИГАТЕЛЯМИ ВНУТРЕННЕГО СГОРАНИЯ

According to the results of the study numeric val-ues of influence dynamics of the excess air factor on fuel consumption by diesel internal combustion engine have been received. Cause and effect relationships between the excess air factor and formation of a mix have been defined, optimum intervals of the excess air factor, temperature and air pressure in an intake mani-fold which provide optimum fuel consumption have been given. 
 The mathematical model of fuel consumption de-pending on the excess air factor has been introduced.
 Studies carried out at the department "Operation of motor vehicles" of the Tyumen Industrial University show that the heating of air in an intake manifold of internal combustion engine KAMAZ 740 up to +67C the temperature interval of the minimum fuel ≤ 2,05 that gives fuel economy consumption increases from-25 to + 77 ° C when to 30 %, especially, at cars opera-tion in severe climatic conditions.

Effect of the fuel/air mixture concentration distribution on the dynamics of a low-emission combustor

An investigation of the low-emission premixed combustion in a conventional combustor is presented. The main problem encountered is the pressure fluctuations induced under certain operating conditions of the combustor. Low-emission operation of the combustor was studied numerically and experimentally. The effect of the concentration distribution at the outlet from the mixing zone on the position and macrostructure of the flame and the combustion stability was investigated at various excess air factors corresponding various GTU loads. It is demonstrated that, for a given excess air factor, there exists the concentration profile such that the interaction of the flame front with dominating flow structures results in excitation of the low-frequency combustion instability. The factors responsible for high-amplitude pressure fluctuations are examined. It is shown that the combustion stability can be estimated using a calculated criterion. Its direct relationship with pressure fluctuation amplitudes is described. The effect of the air pressure in a combustor on the flame macrostructure and the combustion stability was studied. It is shown that an increase in the combustor pressure has no considerable effect on the processes in the combustor. However, a change in the chemical reaction rates affects the stable combustion boundary. In this case, the combustion stability is achieved with higher nonuniformity of the fuel-air mixture entering the combustion zone. The experimental boundaries of stable combustion envelope at an air pressure of 350 and 1500 kPa are presented.

On the effect of temperature and the width of the turbulent combustion zone on the ionization detector readings

We have considered the functional dependence of the ionization detector readings (ion current) on the composition of the fuel–air mixture, adiabatic temperature, and the turbulent combustion zone width. Experiments on the engine show that, for an air excess factor of 0.75–1.15, the coincidence of the calculated and experimental data exceeds 90%. Our results can be used to predict and monitor the adiabatic temperature of the flame and the width of the turbulent combustion zone in the combustion changer of the internal combustion engine using the ionization detector.

Experimental investigation on combustion of hydrogen–oxygen and methane–oxygen mixtures in the medium of low-superheated steam

Experimental data are represented on the investigation of combustion of hydrogen–oxygen and methane–oxygen mixtures in the medium of low-superheated (initial temperature of approximately 150°C) steam at atmospheric pressure. The influence of the ratio of mass flows of the combustible mixture and steam on the qualitative composition of combustion products and the temperature of produced steam is revealed. Main laws for combustion of the hydrogen–oxygen mixture within the steam flow, which affect the completeness of mixture combustion, are determined. Experimental data on the influence of concentrations of the hydrogen–oxygen mixture within the flow of the steam and the combustible mixture upon the completeness of combustion are given. It is found that, when burning the hydrogen–oxygen mixture within the steam flow with a temperature of 1000–1200°C, it is possible using a variation of the combustible mixture flow. At the same time, the volume fraction of noncondensable gases in the produced steam is no more than 2%. It is revealed that there are several combustion modes of the hydrogen–oxygen mixture within the steam flow, in which, in one case, the steam always suppresses combustion and, in another one, detonation of the combustible mixture combustible mixture occurs. It is found that with the excess air factor close to unit, the combustion of the methane–oxygen mixture within steam and the vapor conversion of methane, which result in the appearance of free hydrogen in the produced high-temperature steam, are possible. The description and the principle of the operation of the experimental bench for investigation of combustion of methane–oxygen and hydrogen–oxygen mixtures in the medium of steam are given. Results of experimental investigations of burning fuel and oxygen in the medium of steam are used in the development of a steam superheater for a hightemperature steam turbine.