Combustion Research Articles

The use of modern domestic sources and receivers of the mid-IR range for the detection of combustible gases

The use of modern domestic sources and receivers of the mid-IR range for the detection of combustible gases

Influence of fuel composition on energy parameters of gas turbine plant

PURPUSE. This article describes the possibility of burning natural gas from different fields in a stationary power gas turbine General Electric 6FA. METHODS. Currently, gas turbine technologies are one of the most stably developing areas related to the modernization of generating equipment. At present, modernization of power plants is underway both with gas turbine units and with units in the combined-cycle power unit in the Republic of Tatarstan. The conducted studies allow us to evaluate the effect of the component composition of the fuel on the performance of a gas turbine. Comparative studies make it possible to evaluate changes in the energy characteristics of a gas turbine operating as part of a combined cycle gas turbine unit. RESULTS. The study shows that changes in the fuel composition have an impact on the energy characteristics of a gas turbine plant (efficiency, air consumption). Work with a deviation of the Wobbe index is not permissible. The deviation of the Wobbe index for the city of Zainsk is 5.29%, therefore, when installing a gas turbine it is necessary to change the setting of the fuel system. For synthesis gas, the deviation of the Wobbe index was 22.23%, the use of this fuel is unacceptable without changing the design and setting of the fuel system, since the throughput of the fuel system is not designed for a flow rate of 27.8 kg/s. The smallest values of the amount of CO 2 , NO, O 2 in the composition of the combustion products are achieved on the fuel gas of the city of Kazan. CONCLUSION. The use of synthesis gas as the only fuel is undesirable when operating a gas turbine in a combinedcycle unit, since the calorific value of the flue gases when operating on synthesis gas is minimal and amounts to 94.3 MW, which will affect the operation of the steam turbine.

CH and NO planar laser-induced fluorescence and Rayleigh-scattering in turbulent flames using a multimode optical parametric oscillator.

An optical parametric oscillator (OPO) is developed and characterized for the simultaneous generation of ultraviolet (UV) and near-UV nanosecond laser pulses for the single-shot Rayleigh scattering and planar laser-induced-fluorescence (PLIF) imaging of methylidyne (CH) and nitric oxide (NO) in turbulent flames. The OPO is pumped by a multichannel, 8-pulse Nd:YAG laser cluster that produces up to 225 mJ/pulse at 355 nm with pulse spacing of 100 µs. The pulsed OPO has a conversion efficiency of 9.6% to the signal wavelength of ∼430nm when pumped by the multimode laser. Second harmonic conversion of the signal, with 3.8% efficiency, is used for the electronic excitation of the A-X (1,0) band of NO at ∼215nm, while the residual signal at 430 nm is used for direct excitation of the A-X (0,0) band of the CH radical and elastic Rayleigh scattering. The section of the OPO signal wavelength for simultaneous CH and NO PLIF imaging is performed with consideration of the pulse energy, interference from the reactant and product species, and the fluorescence signal intensity. The excitation wavelengths of 430.7 nm and 215.35 nm are studied in a laminar, premixed CH4-H2-NH3-air flame. Single-shot CH and NO PLIF and Rayleigh scatter imaging is demonstrated in a turbulent CH4-H2-NH3 diffusion flame using a high-speed intensified CMOS camera. Analysis of the complementary Rayleigh scattering and CH and NO PLIF enables identification and quantification of the high-temperature flame layers, the combustion product zones, and the fuel-jet core. Considerations for extension to simultaneous, 10-kHz-rate acquisition are discussed.

ALTERNATIVE DESIGN AND ECONOMIC FEASIBILITY OF AN EXPERIMENTAL WHR FOR INTAKE AIR CONDITIONING OF A LARGE INTERNAL COMBUSTION ENGINE

This work presents an alternative design for an experimental waste heat recovery thermal system to be coupled to a large turbocharged internal combustion engine for combustion air conditioning. The goal is to carry out a design of a new thermal system under restricted economic requirements for one of the generators set of Luiz Oscar Rodrigues de Melo Thermoelectric Power Plant. Thereby, a comparison with the original proposal from previous works is also developed in order to demonstrate the differences in terms of thermo-economic design parameters. The waste recovery thermal system produces sufficient chilled water through a single-effect absorption chiller, powered by hot water which is produced by recovering the exhaust gases residual heat to supply cooling applications on the combustion air. The results showed a significant reduction for the chiller capacity demand, from 550 to 185 RT, that would be enough to provide chilled water for 98.72% of the analyzed operation historical period. The economic feasibility indicators reveal the proposal for the alternative waste heat recovery system as the best financial option, presenting a lower investment cost (US$316,793.27 of savings) and a time for capital recovery of 2.14 years, 1.61 years shorter when compared with the initial WHR system.

Comparative analysis of the energy consumption of cars with different power plants

A comparative analysis of the energy costs of cars with different power plants is carried out. The main advantages and disadvantages of comparable vehicles are considered. Problem. To date, economic and social problems remain global in Ukraine. Air pollution by harmful substances is a very serious concern not only for environmentalists, but for the whole of humanity. The significant drawbacks of a conventional internal combustion engine, namely, exhaust emissions, reduced oil and gas reserves, the constant rise in the cost of motor fuel, are forcing vehicle manufacturers to actively pursue alternative clean energy sources. Goal. The purpose of this work is to perform a comparative analysis of the energy performance of cars with different power units. To achieve this goal it is necessary to solve the following tasks: to consider the energy consumption figures of cars with different power units and compare them; to reveal the main advantages and disadvantages of cars with different drive type. Results. The analysis of publications shows that the use of environmentally friendly car is a modern and promising direction for the development of road transport. The most competitive and effective circuit solution for the construction of such a car today is the use of a hybrid power plant and electric drive. This article provides a comparative analysis of the energy performance of cars with different power units. According to the analysis, the most efficient in terms of energy consumption is the Nissan Leaf electric car – 105 kWh, but when using this car over long distances, it reduces its average operating speed due to downtime at charging stations. The Toyota Corolla, with its traditional gasoline engine, has the highest energy consumption rating of the entire journey – 450 kWh. The Toyota Prius hybrid car has a clear advantage over these cars when used over a long distance of 500 km of energy – 160 kWh, he also has the largest range of 1300 km at one gas station and overcomes this path in 21,6 hours.

Combustion Mechanism of Fe-Nb-B-Y Amorphous Alloys with an Anomalous Exothermic Phenomenon

Combustion Mechanism of Fe-Nb-B-Y Amorphous Alloys with an Anomalous Exothermic Phenomenon

The Heat Transfer Study in the Diesel Engine Combustion Chamber Using a Two-Zone Combustion Model

The study of heat transfer phenomena in diesel engines is a very complex task considering the number of engine components such as intake and exhaust manifolds, lubricant oil and coolant subsystems, the different heat transfer mechanisms (conduction, convection, and radiation). This paper presents simulation results using a dual-zone model associated to GT-Suite simulation software for the calculation of convective heat transfer from gas to the cylinder wall, radiation heat transfer, gas pressure and temperature for low, partial and full load engine as a function of crank angle for a single-cylinder diesel engine. In this present article, a numerical simulation model was created to foresee the main combustion characteristics, and the simulated results were approved through the reference experiment data. Simulation results showed that any increase in the mass of fuel injected into the combustion chamber would generate a significant increase in the level of pressure and temperature of the combustion gases in the cylinder. This means that despite the improved power performance, excessive fuel consumption would have a negative effect on the thermal behavior and consequently on the life of the engine. The essential objective of any combustion engine development is to reduce fuel consumption while maintaining or improving the engine's power output.

Film cooling characteristics on blade platform with a leakage flow through mid-passage gap

Each turbine rotor assembly is composed of several blades, and there is a mid-passage gap between blade platforms. Purge air is supplied through the mid-passage gap to prevent the ingress of hot combustion gas which could lead to thermal damage to the blade platforms. The leakage flow (coolant) egested through the mid-passage gap affects the heat transfer of the blade platform and provides a cooling to the platform. This study investigated the effects of leakage flow on film cooling effectiveness and heat transfer on the platform with a mid-passage gap. The effects of main flow ingestion through the gap on the film cooling effectiveness and heat transfer on the platform were measured for different mass flow ratios (MFRs) of the leakage flow. The film cooling effectiveness was measured using the pressure sensitive paint method, and the heat/mass transfer was measured using the naphthalene sublimation method. The measured mass flow ratios of the leakage flow to the main flow were 0.2%, 0.4%, and 0.6%. At low mass flow ratios (MFR = 0.2%, 0.4%), the main flow ingested under the upstream region of the mid-passage gap and the leakage flow egested through the downstream region of the gap. The egested leakage flow provided a high film cooling effectiveness on the suction side downstream region. However, the leakage flow was egested from the gap with an injection angle of 90° and reattached to the surface, resulting in a high heat transfer in the suction side region near the gap. At a high mass flow ratio (MFR = 0.6%), the leakage flow egested through the entire mid-passage gap, but the leakage flow penetrated into the main flow resulted in a low film cooling effectiveness. As the leakage flow interacted with the main flow and formed a vortex, this resulted a region with film cooling effectiveness decrease and heat transfer increase.

Optical Diagnostics of Temperature and Structural Parameters of an Axisymmetric Flame

In this paper a method for restoring the parameters of multicomponent media for optical diagnostics of jet using the example of a hydrogen-air flame study is considered. Hilbert visualization and numerical modeling of phase perturbations induced by the studied medium in the probing light field are used. The study of the burning jet was carried out using the methods of Hilbert op-tics and Abel transformation in the model of axial symmetry of the torch. A software package has been developed that implements a direct solution to the problem: calculation of the spatial optical phase structure of the flame and its corresponding hilbertograms based on the temperature and molar concentrations of the combustion products of the mixture. The reliability of the obtained results is confirmed by comparing the Hilbert structures obtained in the experiment and the reconstructed optical density field of the phase using the Abel transform. The results of the comparison are used as a quality criterion for modeling the phase structure and temperature field in the study of the combustion process. The developed method can be used to solve the in-verse problem of restoring the temperature field from the Hilbert image of the phase structure of a hydrogen-air flame in the approximation of axial symmetry. The research is motivated by the scientific and practical significance of the problem, which consists in finding methods for controlling the structural and thermodynamic parameters of reacting jets and flames.

Combustion of bituminous coal and semicoke with copper salts

This paper examines combustion of coal and semicoke modified by 5 wt% of Cu(NO3)2, CuSO4 and Cu(CH3COO)2. The additives were introduced using the wet impregnation method. Ignition and combustion experiments were performed in a combustion chamber at temperatures of the heating medium varying from 500 °C to 700 °C. The gas-phase combustion products were analyzed using an in-line gas analyzer. It was found that, on average, the use of activating additives contributed to a reduction of the ignition delay time by 1.8 times and a decrease in the minimum ignition temperature by 54–135 °C. An increase in the heating medium temperature resulted in a significant ignition delay decrease (by ~270%). The maximum difference in the ignition delay time between the reference sample and the modified coal (3.4 s) and semicoke (10.4 s) samples was observed at 500°С while using copper nitrate. In the initial stage of combustion, formation of micro-explosions on the samples modified with copper nitrate and acetate was observed. The use of additives contributed to reducing the content of unburnt carbon in the fuel. Addition of copper salts resulted in a significant reduction in the CO production volume and better fuel oxidation to CO2.

Time-lapse electrical resistivity tomography mapping of DNAPL remediation at a STAR field site

Time-lapse Electrical Resistivity Tomography (ERT), a surface geophysical technique, was applied for the first time to directly map in-situ DNAPL destruction at a field site. Time-lapse ERT was used to map remediation of coal tar at a site undergoing full-scale application of Self-sustaining Treatment for Active Remediation (STAR). STAR is an in situ thermal treatment based on smoldering combustion that destroys dense non-aqueous phase liquids (DNAPLs) while generating heat, water, and combustion gases. ERT was used to provide spatially and temporally resolved data to complement the conventional discrete and overview data normally collected during STAR operations. A STAR treatment cell targeting coal tar at 2.4 mbgs and below the water table was monitored with 2D surface resistivity surveys conducted before, during and after treatment. Two 36-electrode lines, each 21 m long, were employed. Relative resistivity ratio maps and discrete (nodal) resistivity signal analysis both proved useful in numerous ways. For example, ERT was demonstrated to map likely treated coal-tar zones. This was accomplished by identifying a characteristic, local, temporal resistivity signal pattern corresponding to STAR-induced subsurface temperature and liquid saturation changes. In addition, ERT identified the subsurface areas (i) effectively captured by the vapor extraction system, (ii) possibly missed by the vapor capture system where gases built-up, and (iii) where and when re-infiltration of groundwater occurred post-treatment. In addition, the overall average subsurface resistivity provided a useful metric to correlate with traditional site measures of treatment such as the cumulative amount of DNAPL mass treated. This study provides a successful proof of concept however the maximum potential of the approach is expected with a full 3D survey. Overall, the resistivity surveys provided valuable continuous mapping of the subsurface, including the locations of DNAPL mass destruction, and showed that ERT is promising for supporting evaluations of in situ remediation programs.

SUBSTANTIATION OF USE OF BUTANE FOR GASIFICATION OF OBJECTS

Statement of the problem. The variable composition of liquefied petroleum gas has a significant impact on the operation of autonomous gas supply systems. The presence of the butane fraction under conditions of sub-zero temperatures leads to the cessation of the generation of the vapor phase in the tank, moisture condensation and the formation of ice and hydrate plugs.Results. The features of the use of technical butane in gas supply systems are considered. The composition of the gas-air mixture is recommended, taking into account the restrictions on deviations in the Wobbe number, ensuring the completeness of combustion of the mixture in gas-using installations of the consumer. The level of filling underground tanks with technical butane is justified, taking into account the coefficient of volume expansion of gas in the presence of extreme operating temperatures.Conclusions. The composition of butane-based gas-air mixtures for gas supply to consumers was determined that meets the condition for the interchangeability of combustible gases and provides lower dew point temperatures; the level of filling of ground and underground tanks with technical butane is justified.

EFFICIENCY OF GAS-FIRED HEAT GENERATORS FOR INDIVIDUAL AND DECENTRALIZED HEATING SYSTEMS

Modern equipment for heating systems of residential consumers, public buildings is characterized by a significant variety of design and efficiency. Gas-fired heat generators have several advantages when compared with devices on other types of fossil fuels. The main advantages of gas heat equipment are to reduce emissions into the environment, increase the efficiency. For consumers, an important aspect is the economic reduction of heating costs, the ability to control and regulate, the high security of modern systems using gas fuel. The safe use and high efficiency of gas heating equipment depends on a number of factors. The first, it is the use of gas fuel corresponding to the specified parameters. Secondly, it is the organization of the process of supplying air and removing combustion products for burning. Thirdly, it is the process of supplying gas with specified parameters, which is determined by the process of functioning of the gas distribution network. The article describes the work of gas heat generators at different temperatures of the incoming combustion air. Depending on the installation of the equipment, the air temperature for combustion may differ significantly from the temperature at which the heat generators were tested. Thus, the efficiency will differ from that stated in the passport when the temperature of the air entering the combustion changes. In the gas heat generators, there are a number of losses associated with chemical, mechanical incomplete burning, losses with products of combustion. In the work, all losses were analyzed, and the efficiency of a gas heat generator of 60 kW power was determined. As a result of the study, the annual effect in terms of gas volume was determined for given conditions.

Visual experimental investigation on stable operating process of the plane-radial rotating detonation engine

Using visual observation methods, assisted by synchronous measurement of dynamic pressure and ion tracks, the flow field structures of stable operating modes in plane-radial rotating detonation engine (RDE) are revealed, and the influences of injection conditions on the RDE stable operating range are analyzed. The flow field structures of single-wave mode, symmetric dual-wave mode and triple-wave mode are observed. Typical structures such as rotating detonation wave (RDW), oblique shock wave, combustion products, deflagration surface and contact discontinuity are obtained in the flow fields. Obvious reactants pre-combustion ahead of detonation wave is found in the combustor, and low-frequency oscillation phenomenon is gained under specific conditions. With the increase of wave-head number in combustor, the detonation-wave height and parameters decrease. The RDW propagating velocity and pressure peak are higher in single-wave operating mode, but the flow fields in multi-wave mode are more stable. Both the RDW velocity and pressure peak increase generally with equivalence ratio. Keeping the equivalent ratio (ER) fixed, as the mass flow rate increases, the number of detonation wave in combustor increases, and the operating mode transforms from single-wave mode to multi-wave mode. Keeping the mass flow rate fixed, when the equivalent ratio deviates from stoichiometric ratio, the operating mode varies from multi-wave mode to single-wave mode. Additionally, with the mass flow rate increasing, the ER upper and lower limits of multi-wave mode decrease linearly, and the operating range of dual-wave mode remains unchanged. Mass flow rate has little influence on the ER lower limit of the RDE stable operation, which is approximately ER=0.55 in this structure.

INVESTIGATION OF CORROSIVE EFFECT ON METAL OF A BROAD FUEL FRACTION OBTAINED FROM SECONDARY POLYMER RAW MATERIAL

A research of the corrosion effect on the metal (copper plate) of a broad fuel fraction (FPF) - a liquid product of thermal destruction of secondary raw materials made of low pressure polyethylene (LDPE) at temperatures up to 380 ° C and a pressure of 0,12-0,15 MPa. is conducted. Determination of the corrosion effect on the copper FFT plate was carried out in accordance with the standard ASTM D 130-10 at a temperature of 50 ° C for 120 minutes for both the dehydrated FFT sample and in the presence of 1% water. It was found that the copper plates, which were in the FFT and FFT + 1% water in the visual evaluation, had a light orange color, close to the color of the original plate. This, in turn, indicates that the investigated FFT samples have withstood the test, and the corrosive effect on the copper plate can be attributed to a slight fading, class 1.a. Also, together with the study under standard conditions, the corrosion effect on the copper plate of the products of combustion of FFT at different temperatures at which it was found that in the temperature range 180-230 ° C the surface of the copper plate becomes pale purple, and the corrosion effect on the copper plate can be attributed to moderate dimming, class 2.b; at temperatures of 230-290 ° the surface of the copper plate already has a silver color, and the corrosive effect on the copper plate corresponds to a moderate blackout, class 2.d. Therefore, when the combustion products of the FFT on the copper plate only oxygen corrosion occurs, which is due to the presence of oxygen in the area of the copper plate and the temperature of the combustion products. Thus, it was concluded that there is no corrosive elements in the FFT, which makes it suitable for use as a cheap component of motor, furnace and boiler fuels, improving their performance (e.g., reducing sulfur content).

Emission Characteristics from Vehicles at Idling Condition.(Dept.M)

The present study aims to evaluate the emission characteristics for gasoline-fueled vehicles at idling condition. Factors influencing the formation of emissions at different operating conditions are examined. The study is focused on the ignition parameters as well as the mixture quality which are the most important factors affecting the engine performance and emission. A wide range of spark plug gap(0.3- 1.9) mm and ignition timing (10- 1900 BTDC)were employed in the present study. The mixture quality at idling is varied along the flammability limit to clarify its effect on the combustion products concentration. The measurements were carried out on a specified vehicle. Both the engine speed and combustion products concentration were recorded simultaneously. The results indicate the importance of adjusting the idling condition to optimize the exhaust products.

CORRECTION OF PROPERTIES OF MODERN DIESEL FUELS USING ADDITIVES

Creation of high quality diesel fuels for internal combustion engines that meet stringent operational and environmental requirements is currently an urgent task. The most rational way to improve the performance characteristics of diesel fuel, its environmental properties, as well as to reduce losses during its storage, is to use polyfunctional additives. Requirements for the structure of polyfunctional additives are formulated. It is shown that their stabilizing and protective effects are the higher, the greater the value of the dipole moment and total electron density on heteroatoms. Amides and esters of higher aliphatic acids, synthesized from renewable diesel raw materials, as well as molecules of azo compounds including aromatic fragments and electron-donating functional groups, are promising multifunctional additives to diesel fuel.

Quantitative characterisations of spray deposited liquid films and post-injection discharge on diesel injectors

Transient injection phases have been identified as a prominent source of inefficiencies and exhaust gas constituents detrimental to both public health and the environment. The rapid reduction of in-nozzle flow rate at the end of diesel injection events inhibits spray atomisation and releases large slow-moving liquid structures into the cylinder. This uncontrolled release of fuel results in wetting of the nozzle surface through rogue droplets diverting back towards the nozzle. The resulting films create fuel-rich regions that may later get drawn into the exhaust, contributing to engine-out emissions. They also present an ideal environment for reactions with combustion products and adherence of deposit precursors. Despite recent experimental advances there is a lack of quantitative data relating the operating conditions to the quantity of fuel deposited on nozzle orifices.To improve our understanding of the underlying near-nozzle and surface-bound processes, we applied high-speed optical microscopy under conditions relevant to passenger vehicles. Image processing techniques were used to quantify the deposition of fuel films and their spreading with time. A single component fuel (n-dodecane) was injected using an injector instrumented with a thermocouple to measure the sub-surface nozzle tip temperature. Injection duration, timing and pressure were varied to reveal their influence on the deposition and overspill of fuel onto the nozzle.We conclude by presenting an analysis of the film behaviour as function of injection pressure, in-cylinder pressure and bulk gas temperature. Relative to the conditions investigated, spray wetting was more pronounced at the reduced load conditions.

Influence of methane on the prediction index gases of coal spontaneous combustion: A case study in Xishan coalfield, China

Lean-oxygen environment caused by methane in high gassy coal mine goaf has a significant influence on the prediction index gases of residual coal spontaneous combustion. The coal sample from Xishan coalfield in China was used to conduct the low-temperature oxidation experiments under different lean-oxygen environments. The experimental results show that different lean-oxygen environments had a significant delay effect on the formation of CO, CO2, H2 and C2H6, and the lower the O2 concentration, the more obvious the delay effect, and the delay effect of methane was greater than that of N2. A lean-oxygen environment caused by methane also had a significant influence on the values of CO/ΔO2 ratio and CO2/ΔO2 ratio. However, when the temperature was < 170 °C, the change of O2 concentration had no significant influence on the value of CO/CO2 ratio, and the relationship between the value of CO/CO2 ratio and temperature T can be accurately expressed by exponential function. The absolute amount of CO, CO2 and C2H6 generated by 1kg residual coal (CCO, CCO2 and CC2H6), which can reduce the influence of air leakage and residual coal mass on prediction index gases, were introduced to predict the spontaneous combustion in high gassy coal mine goaf. Then, the distribution diagrams of CCO, CCO2 and CC2H6 with temperature and O2 concentration were obtained, so as to accurately predict the degree of spontaneous combustion in high gassy coal mine goaf. The research results are of great significance to the prevention of spontaneous combustion in goaf of high gassy mine.

Book review: A Gallery of Combustion and Fire

Book review: A Gallery of Combustion and Fire