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Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article discusses one of the ways to increase the economic efficiency of the Gazprom Transgaz Kazan Limited Liability Company (Gazprom Transgaz Kazan LLC) in the operation of gas heaters at a gas distribution station by replacing the gas heating unit. The advantages of the equipment «ISTOK-60» over PTPG-30 are described, the calculation of the economic effect from the introduction of new equipment is given. The object of the study is the process of operating gas heaters at the gas distribution station of OOO Gazprom Transgaz Kazan, the subject is a method for increasing the economic efficiency of gas heaters. As a result of the study, the expediency of replacing old equipment with new one is proved and the economic effect is calculated. The article also raises questions about the possibility of using the concept of «Lean production» in the process of gas distribution. One of the methods of lean manufacturing — SMED is proposed as the main one.

Material treatment in pulsation reactors (PRs) offers the potential to synthesize powdery products with desirable properties, such as nano-sized particles and high specific surface areas, on an industrial scale. These exceptional material characteristics arise from specific process parameters within PRs, characterized by the periodically varying conditions and the resulting enhanced heat and mass transfer between the medium and the particulate material. Understanding flame behavior and the re-ignition mechanism is crucial to controlling the efficiency and stability of the pulse combustion process. In order to accomplish this objective, an investigation was conducted into flame behavior within the combustion chamber of a Helmholtz-type pulsation reactor. The study was focused on primarily analyzing the flame propagation process and examining flame velocity throughout the operational cycle of the reactor. Two optical methods—natural flame luminosity (NFL) and particle image velocimetry (PIV)—were applied in related experiments. An analysis of the NFL measurement data revealed a correlation between the intensity of light emitted by the pulsed flame and the air-fuel equivalence ratio (range from 0.89 to 2.08 in this study). It is observed that a lower air-fuel equivalence ratio leads to higher flame luminosity in the PR. In addition, in order to study the parameters related to system stability and energy transfer efficiency, this study also focuses on the local velocity field measurement method and an example of a fluid flow result in a combustion chamber by using a phase-locked PIV measurement system upgraded from a classic PIV system. The presented results herein contribute to the characterization of flame propagation within a pulsation reactor, as well as in pulsatile flows over one working cycle in a broader context, with flow velocity in the center of the combustion chamber ranging from 1.5 m/s to 5 m/s. Furthermore, this study offers insights into the applicable experimental methodologies for investigating the intricate interplay between flames and flows within combustion processes. [ABSTRACT FROM AUTHOR]

Material treatment in pulsation reactors (PR) brings the possibility of synthesizing powdery products with advantageous properties, such as nanoparticle sizes and high specific surface areas, at an industrial scale. The extraordinary material properties can be ascribed to special process parameters in a PR, primarily the periodically varying conditions and the consequently enhanced heat and mass transfer between the medium and the particles of the material. Understanding the connections between the PR operation parameters, such as fuel and air intake or PR geometry, and the resulting process parameters (temperature distribution, flow velocity and pressure field, and frequency of the pulsations) is essential to enabling a controllable treatment process. Despite the long history of pulsation reactor technology, many connections and dependencies remain unclear. Thus, the influence of the fuel (and air) supply on the pulsation reactor behavior is experimentally examined in this study. The investigated PR characteristics and process parameters are primarily those that have an impact on the heat and mass transfer, i.e., the temperature distribution, flow velocity, and pressure field, and frequency of the pulsations. In addition to these, the harmonic distortion of the oscillations and the heat losses are evaluated. [ABSTRACT FROM AUTHOR]

The kinetic characteristics of propagating flame were shown to depend on the chemical properties of the contacting solid surface and on the rates of heterogeneous recombination of active intermediate particles. The flame influences the chemical properties of the surface, which, in turn, affects the characteristics of flame propagation. Flame propagation occurs in a pulsating mode, whose characteristics also depend on the chemical properties of the surface. Due to the pulsating nature of combustion and variability of the surface properties and kinetic parameters of heterogeneous reactions during combustion, the reliability of mathematical modeling of flame propagation is extremely low. [ABSTRACT FROM AUTHOR]

This work presents a 2D numerical simulation of the nonpremixed combustion of natural gas in an axisymmetric cylindrical chamber, focusing on the effect of adding acoustical excitation to inlet fuel velocity on temperature, exhaust pollutants, and combustion products velocity. Pulsation combustion generates vortices and enhances mixing, which in turn increases combustion efficiency and reduces emissions so it is used in many industrial applications like dryers and boilers. The turbulence is solved using detached eddy simulation model, which is a hybrid modeling between large eddy simulation and realizable k-e model. The chemical reactions are described by the eddy dissipation model. The radiative intensity transport equations are solved using P-1 radiation model. The numerical model achieved a great agreement with experimental data on temperature and species mass fraction. The main outcome of the work is the demonstration of a significant decrease in a volume of pulsed flame compared to a nonpulsed flame with 18% reduction in the flame length. Increasing the Strouhal number enhances the temperature homogenization along the combustion chamber and the flame does not concentrate in the chamber core and toward the chamber exhaust. Changing the fuel velocity from the stoichiometric ratio due to the fuel pulsation cools the chamber and reduces the average temperature from 2000 to 1750 K. There was a reduction in the mass fraction of carbon monoxide, nitrogen monoxide and soot by 50, 28, and 285%, respectively. Increasing fuel frequency increases maximum velocity by 66% axially and 14% radially. [ABSTRACT FROM AUTHOR]

The present study represents a numerical simulation of the experimental diffusion combustion of liquified petroleum gas with pulsating air in a cylindrical chamber. The simulation focused on the effect of mixing air inlet square shape with pulsation combustion on the temperature, combustion products velocity, turbulent viscosity, carbon monoxide, mass fraction of nitric oxide and soot. The simulation is applied by Ansys fluent 16 commercial packages solving probability density function equation and large eddy simulation. The sinusoidal air inlet velocity had a frequency of 200 rad/s with 3.4 m/s velocity amplitude. Two air inlet ports are used circular and a square shape which all have an equivalent inlet area of 120 mm2. The numerical results are compared to experimental results of circular shape and achieve an acceptable agreement. It is noticed that the excitation leads to widening of the flame zone and a decrease in the flame length by 55%, also the average temperature decreases from 2050 to 1650 K in square shape and from 1900 to 1600 K in circular shape. The mass fraction of carbon monoxide, nitrogen oxide, and soot are reduced by 23%, 88% and 60%, respectively due to the pulsation and the addition of the sharp corner to the pulsation reduced them by 30%, 92%, and 70%, respectively. [ABSTRACT FROM AUTHOR]

The article describes the problem of measuring the temperature in a pulse combustion chamber. The object of the study is a valveless pulsejet. The problem is analysed on the example of exhaust gases temperature measurement. The measurement in these conditions requires the use of a sensor resistant to large changes in gas velocity and temperature and at the same time with adequatly low inertia. This excludes the use of fast and precise yet thin, resistant wire sensors or ultrafast thin film thermocouples. Finally, a temperature measurement system based on sheated thermocouples was chosen. During each test the thermocouple has its own temperature which is different from the medium temperature. In order to properly determine the measured temperature of flowing media it is necessary to take the sensor time characteristics into account. In this article the iteration method is proposed to solve this problem. [ABSTRACT FROM AUTHOR]

The formation of the combustion flame in the heating channels of coke batteries is considered. The changes in the flame configuration when water vapor is supplied to the heating channels are described. The associated formation and collapse of water-vapor bubbles disrupts the continuity of the medium, resulting in instantaneous interruption of the flame. Such discontinuity is known as pulsating combustion. As a result, the flame is extended, and the temperature distribution over the height of the coke chamber becomes more uniform. By adjusting the quantity of water vapor supplied, the degree of pulsation and hence the flame height may be regulated. In addition, the supply of water vapor to the heating channels is accompanied by decrease in the content of incomplete-combustion products such as oxides of nitrogen and carbon monoxide. [ABSTRACT FROM AUTHOR]

We have studied simplified, pulsating, one-dimensional, in situ combustion processes. For two cases, with different reaction stoichiometry, oscillations in temperature, flue gas rate, and flue gas composition are demonstrated and the parameter space resulting in oscillatory behavior is identified. To understand the role of different parameters, linear stability of the problem is studied. Because linear stability analysis requires the solution of uniform front propagation, we investigated an asymptotic analytical solution of the problem. We found an original formula for the front propagation velocity. The analytical solution enabled us to define four dimensionless parameters including Zeldovich (Ze) number, Damkohler (Da) number, a specialized air-fuel ratio (B), and a ratio incorporating air and rock heat capacities (Δ1). Using linear stability analysis, we show that the stability of the problem is also governed by these four parameters. Because Δ1 ≈ 1 for typical laboratory conditions, the set of (Ze, Da, B) is used to construct the stability plane; consequently, several important design considerations are suggested. Both larger air injection rate and air enriched in oxygen increase the front propagation speed but push the system toward oscillatory behavior. Conversely, the introduction of catalysts and metal additives, that decrease the activation energy of reactions, increases the front speed and stability. Similarly, increasing the amount of fuel available for the combustion makes the design more stable and drives the combustion front to propagate more quickly. [ABSTRACT FROM AUTHOR]

Pulsating combustion has the advantages of high combustion intensity, high heat transfer coefficient, and low pollutant emission, and therefore it has been widely used to enhance the heat transfer process, such as aeromodelling’s power, material drying, and pest control. In recent years, pulsating combustion heater, such as hot water boiler or steam boiler, has become another new application of pulsating combustion technology. Pulsating combustion heater employs the pulsating burner as the heat source, and the main components such as combustion chamber and tail pipe are immersed in heating medium (such as oil and water). When the pulsating burner works, heat is transferred to the heating medium through the high temperature outer wall of the combustion chamber and tail pipe, and then the heating medium is heated to the temperature required by the process. The efficiency and the economy of the pulsating combustion heater were related to the temperature increasing process of the heating medium. In order to investigate the characteristics of temperature distribution of airflow field outside combustion chamber of the pulsing burner, a two-dimensional unsteady numerical model was established. The increasing-temperature process in the central cross section of combustion chamber was simulated by Fluent software under the conditions of 5 different kinds of oil consumption (30°, 60°, 90°, 120°, and 150° throttle opening), employing a self-excited and self-suction Helmholtz pulsing burner as the heat source. Temperature increasing process of the pulsating burner in the heating medium was difficult to obtain, but it was easier to obtain in the air. The temperature increasing process of the heat source in the air was obtained by an infrared thermal cameral under all kinds of different oil consumption. Formula fitting was carried out for the increasing-temperature process. The fitted values and measured values were in good agreement. The maximum temperature difference between the fitted data and measured results was 5.2 °C and the maximum relative error was 2.2%. The temperature increasing law of the heat source was added to the numerical model by UDF (user-defined function) interface. A series of tests were performed to investigate the accuracy of the numerical model. It was found the simulation values were matched with the test data quite well, and the average relative error was between 2.68% and 5.54%. Temperature elevation of airflow field outside combustion chamber showed an “S” shape. In the beginning, air temperature increased rapidly. After a period of time, the temperature tended to be stable. With the increase of throttle opening, there was little difference in temperature increasing process for one single test point. The closer the distance to the combustion chamber in the same direction, the shorter the time it took to reach the maximum temperature, and the higher the temperature increasing speed and the maximum temperature. The test points above the combustion chamber got the higher temperature increasing speed and the higher maximum temperature than the test points which were at the right and the bottom of the combustion chamber when they were in the same distance to the combustion chamber. The 4 test points above the combustion chamber reached the highest temperature at 1.25 min, but the time required for the test points at the right and the bottom of the combustion chamber varied from 2 to 5 min when the throttle opening was 120°. The airflow outside the combustion chamber was driven upward from the bottom under the influence of density difference. Karman vortex street was observed when the airflow passed the combustion chamber, and the airflow temperature field above the combustion chamber oscillated periodically. As the vortices moved upward, their influence on the airflow temperature field was gradually weakened, and the temperature amplitude gradually decreased. This paper can be helpful to further understand the heating process of internal temperature field of the pulsating combustion heater when using oil or water as heating medium, and it also can provide references to optimize heat source structure design inside the pulsating combustion heater. [ABSTRACT FROM AUTHOR]

This paper shows the results of studying the influence of a plasma-chemical stabilizer on the pulse parameters of a gas turbine low emissive combustor. It is found out that the increase of the processes stability in low emissive gas turbine combustors with preliminary formation of air-fuel mixture may be reached due to plasma-chemical influence of the plasma-assisted systems based on low-current discharges on the processes of mixture formation and chemical kinetics. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical Engineering the National Technical University of Ukraine 'Kyiv Polytechnic Institute' is the property of National Technical University of Ukraine KPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The NOx emission under acoustic excitation and no-excitation were compared on methane laminar partially premixed flame. The mechanism of NOx was analyzed by micro-thermocouple, water-cooled sampling probe. The experimental results show that compared with no-excitation combustion, pulsating combustion produced less NOx emissions. There are two reasons including: (1)peak temperature was reduced and the distribution of temperature was more uniform, (2)the oxygen of flame was increased for rapid mixing rate and the reaction rate was enhanced. [ABSTRACT FROM AUTHOR]

The pulsating combustion process has attracted interest in current research because its application in energy generation can offer several advantages, such as fuel economy, reduced pollutants formation, increased rate of convective heat transfer and reduced investment, when compared with other new techniques of combustion. An experimental study has been conducted with the objective of investigating the effects of combustion driven acoustic oscillations in the emission rates of combustion gases, especially carbon monoxide and nitrogen oxides, and soot presence in partial premixed flames in confined partially premixed liquefied petroleum gas flames. The results basically showed that a more uniform fuel/air mixture due to the presence of an acoustic field increases the NOx emissions in operations close to stoichiometric equivalence ratios and the frequency is the most important parameter. Carbon monoxide and soot reduced significantly. [ABSTRACT FROM AUTHOR]

Abstract: This paper shows the experimental results for changes in the flame structure when acoustic fields are applied in natural gas Delft turbulent diffusion flames. The acoustic field (pulsating combustion) generates zones of intense mixture of reactants in the flame region, promoting a more complete combustion and, consequently, lower pollutant emissions, increase in convective heat transfer rates, and lower fuel consumption. The results show that the presence of the acoustic field changes drastically the flame structure, mainly in the burner natural frequencies. However, for higher acoustic amplitudes, or acoustic pressures, a hydrogen pilot flame is necessary in order to keep the main flame anchored. In the flame regions where the acoustic field is more intense, premixed flame characteristics were observed. Besides, the pulsating regime modifies the axial and radial combustion structure, which could be verified by the radial distribution of concentrations of O2, CO, CO2, and NO x , and by the temperature profile. The experiments also presented the reduction of flame length with the increase of acoustic amplitude. [Copyright &y& Elsevier]

Quasi-simultaneous phase-correlated measurements of different species in a turbulent swirl flame with a self-excited instability are presented for the first time. Phase-resolved OH* chemiluminescence and planar laser-induced fluorescence (PLIF) spectroscopy of OH, CH, and H 2 CO were used to follow the temporal evolution of flame structures in a pulsating swirl-stabilized model injector for gas-turbine applications. H 2 CO is a suitable indicator for chemical heat release in combination with OH; CH LIF and OH* emission were shown to be suitable indicators for the average shape and location of flame fronts, while OH LIF marked regions with high temperature, both in the flame front and the burned gas regions. The combustor was operated on methane fuel at atmospheric pressure. Lasers and detectors were locked to the phase angle of the self-excited pressure oscillation using a trigger signal derived from a microphone. Measurements at different phase angles were performed by variable delays with respect to the trigger pulse. Due to a high degree of turbulence, a large number of single-pulse measurements at each phase angle had to be performed in order to retrieve phase-sensitive effects from the dominating turbulent fluctuations. Noticeable changes of the flame structure with phase angle, particularly near the injector exit, are indicative of a strong coupling between the flame and a periodically fluctuating flow field. [ABSTRACT FROM AUTHOR]

The inlet geometry of the combustion chamber of a Helmholtz type pulse combustor was changed by altering the position of a stagnation plate, or flame holder, near the inlet. Three different flame holder positions were studied. The operating characteristics in terms of time resolved pressure and heat release, time averaged tail pipe temperature and concentrations of O2and NOxin the outlet decoupler were investigated. These quantities were measured and also simulated in a model based upon the LES concept. The effect of different flame holder positions on the operating characteristics is discussed. The simulation model was found able to satisfactorily describe the combustion processes for all three cases, although the results indicate that some sub models need further improvement. [ABSTRACT FROM PUBLISHER]

This paper presents the results of a controlled acoustic excitation of a liquid fueled non-premixed flame as a means of nitric oxide reduction. The experimental burner is a domestic hot-water heater provided by Viessmann. An actuator is located on the air duct and comprises two perforated plates. By changing the speed of rotation of the rotor it is possible to achieve a single frequency excitation of the burner cavity. The industrial version of the burner already features low NO, exhaust levels (82 ppm at 0% 02)and satisfies the current European regulations concerning pollutant emissions. Its operating point corresponds to an equivalence ratio of 0.82. It is shown that for a broad range of frequencies (100 Hz to 700 Hz) the overall nitric oxide emissions are reduced up to 15%. Radical imaging of the excited flames shows strong effects of the excitation on the flame geometry, especially on the flame length, and gives guidelines to a new, more effective, NO., emission control using acoustic excitation. [ABSTRACT FROM PUBLISHER]