scholarly journals Numerical Modelling and Experimental Verification of the Low-Emission Biomass Combustion Process in a Domestic Boiler with Flue Gas Flow around the Combustion Chamber

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5837
Author(s):  
Przemysław Motyl ◽  
Danuta Król ◽  
Sławomir Poskrobko ◽  
Marek Juszczak
Keyword(s):  
Combustion Chamber ◽  
Gas Flow ◽  
High Efficiency ◽  
Combustion Process ◽  
Experimental Studies ◽  
Numerical Calculations ◽  
Biomass Combustion ◽  
The European Union ◽  
Wood Pellets ◽  
Low Emission

The paper presents the results of numerical and experimental studies aimed at developing a new design of a 10 kW low-emission heating boiler fired with wood pellets. The boiler is to meet stringent requirements in terms of efficiency (η > 90%) and emissions per 10% O2: CO < 500 mg/Nm3, NOx ≤ 200 mg/Nm3, and dust ≤ 20 mg/Nm3; these emission restrictions are as prescribed in the applicable ECODESIGN Directive in the European Union countries. An innovative aspect of the boiler structure (not yet present in domestic boilers) is the circular flow of exhaust gases around the centrally placed combustion chamber. The use of such a solution ensures high-efficiency, low-emission combustion and meeting the requirements of ECODESIGN. The results of the numerical calculations were verified and confirmed experimentally, obtaining average emission values of the limited gases CO = 91 mg/Nm3, and NOx = 197 mg/Nm3. The temperature measured in the furnace is 450–500 °C and in the flue it was 157–197 °C. The determined boiler efficiency was 92%. Numerical calculations were made with the use of an advanced CFD (Computational Fluid Dynamics) workshop in the form of the Ansys programming and a computing environment with the dominant participation of the Fluent module. It was shown that the results obtained in both experiments are sufficiently convergent.

scholarly journals Design and development of combustion chambers for gas turbine engines based on calculations of various levels of complexity

2021 ◽  
Vol 20 (3) ◽  
pp. 7-23
Author(s):  
Y. B. Aleksandrov ◽  
T. D. Nguyen ◽  
B. G. Mingazov
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Flow ◽  
Combustion Process ◽  
Three Dimensional ◽  
Numerical Calculations ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Combustion Chambers ◽  
Flame Tube

The article proposes a method for designing combustion chambers for gas turbine engines based on a combination of the use of calculations in a one-dimensional and three-dimensional formulation of the problem. This technique allows you to quickly design at the initial stage of creating and development of the existing combustion chambers using simplified calculation algorithms. At the final stage, detailed calculations are carried out using three-dimensional numerical calculations. The method includes hydraulic calculations, on the basis of which the distribution of the air flow passing through the main elements of the combustion chamber is determined. Then, the mixing of the gas flow downstream of the flame tube head and the air passing through the holes in the flame tube is determined. The mixing quality determines the distribution of local mixture compositions along the length of the flame tube. The calculation of the combustion process is carried out with the determination of the combustion efficiency, temperature, concentrations of harmful substances and other parameters. The proposed method is tested drawing on the example of a combustion chamber of the cannular type. The results of numerical calculations, experimental data and values obtained using the proposed method for various operating modes of the engine are compared.

EXPERIMENTAL STUDIES ON THE CORROSION OCCURRENCE DURING BIOMASS COMBUSTION PROCESS

2012 ◽  
Vol 11 (9) ◽  
pp. 1555-1560 ◽  
Author(s):  
Ionel Pisa ◽  
Gheorghe Lazaroiu ◽  
Corina Radulescu ◽  
Lucian Mihaescu
Keyword(s):  
Combustion Process ◽  
Experimental Studies ◽  
Biomass Combustion

scholarly journals Experimental Studies of Fuel Injection in a Diesel Engine with an Inclined Injector

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2643
Author(s):  
V. G. Kamaltdinov ◽  
V. A. Markov ◽  
I. O. Lysov ◽  
A. A. Zherdev ◽  
V. V. Furman
Keyword(s):  
Combustion Chamber ◽  
High Speed ◽  
Cone Angle ◽  
Combustion Process ◽  
Experimental Studies ◽  
Uneven Distribution ◽  
Orifice Diameter ◽  
Spray Cone ◽  
Fuel Sprays ◽  
The Difference

Comparative experimental studies of fuel sprays evolution dynamics in a constant volume chamber were carried out with a view to reduce the uneven distribution of diesel fuel in the combustion chamber when the Common Rail injector is inclined. The fuel sprays was captured by a high-speed camera with simultaneous recording of control pulses of camera and injector on an oscilloscope. Two eight-hole diesel injectors were investigated: One injector with identical orifice diameter (nozzle 1) and another injector with four orifices of the same diameter as orifices of nozzle 1 and four orifices of enlarged diameters (nozzle 2). Both injectors were tested at rail pressure from 100 to 165 MPa and injector control pulse width of 1.5 ms. The dynamics of changes in the spray penetration length and spray cone angle were determined. It was found that sprays develop differently in nozzle 1 fuel. The difference in the length of fuel sprays is 10–15 mm. As for nozzle 2, the fuel sprays develop more evenly: The difference in length is no more than 3–5 mm. The difference of the measured fuel spray cone angles for nozzle 1 is 0.5°–1.5°, and for nozzle 2 is 3.0°–4.0°. It is concluded that the differential increase in the diameters of nozzle orifices, the axes of which are maximally deviated from the injector axis, makes it possible to reduce the uneven distribution of fuel in the combustion chamber and improve the combustion process and the diesel performance as a whole.

Phenomenological Modeling of Combustion in Pre-Chamber and the Pilot Flame for Natural Gas Engines

2019 ◽  
Author(s):  
Long Liu ◽  
Xia Wen ◽  
Qian Xiong ◽  
Xiuzhen Ma
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Alternative Fuels ◽  
Gas Flow ◽  
Combustion Process ◽  
Clean Energy ◽  
Combustion Model ◽  
Flame Surface ◽  
Flow Process ◽  
Natural Gas Engines

Abstract With energy shortages and increasing environmental problems, natural gas, as a clean energy, has the advantages of cheap price and large reserves and has become one of the main alternative fuels for marine diesel engines. For large bore natural gas engines, pre-chamber spark plug ignition can be used to increase engine efficiency. The engine mainly relies on the flame ejected from the pre-chamber to ignite the mixture of natural gas and air in the main combustion chamber. The ignition flame in the main combustion chamber is the main factor affecting the combustion process. Although the pre-chamber natural gas engines have been extensively studied, the characteristics of combustion in the pre-chamber and the development of ignition flame in the main combustion chamber have not been fully understood. In this study, a two-zone phenomenological combustion model of pre-chamber spark-ignition natural gas engines is established based on the exchange of mass and energy of the gas flow process in the pre-chamber and the main combustion chamber. The basic characteristics of the developed model are: a spherical flame surface is used to describe the combustion state in the pre-chamber, and according to the turbulent jet theory, the influence of turbulence on the state of the pilot flame is considered based on the Reynolds number. According to the phenomenological model, the time when the flame starts to be injected from the pre-chamber to the main combustion chamber, and the parameters such as the length of the pilot flame are analyzed. The model was verified by experimental data, and the results showed that the calculated values were in good agreement with the experimental values. It provides an effective tool for mastering the law of flame development and supporting the optimization of combustion efficiency.

Method for Determining Instantaneous Temperature at the Surface of Combustion Chamber Deposits in an HCCI Engine

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Orgun Güralp ◽  
Paul Najt ◽  
Zoran S. Filipi
Keyword(s):  
Surface Temperature ◽  
Combustion Chamber ◽  
High Efficiency ◽  
Combustion Process ◽  
Heat Transfer Process ◽  
Valuable Insight ◽  
Hcci Combustion ◽  
Crank Angle ◽  
Instantaneous Temperature ◽  
Combustion Chamber Deposits

Homogeneous charge compression ignition (HCCI) combustion is widely regarded as an attractive option for future high efficiency gasoline engines. HCCI combustion permits operation with a highly dilute, well mixed charge, resulting in high thermal efficiency and extremely low NOx and soot emissions, two qualities essential for future propulsion system solutions. Because HCCI is a thermokinetically dominated process, full understanding of how combustion chamber boundary thermal conditions affect the combustion process are crucial. This includes the dynamics of the effective chamber wall surface temperature, as dictated by the formation of combustion chamber deposits (CCD). It has been demonstrated that, due to the combination of CCD thermal properties and the sensitivity of HCCI to wall temperature, the phasing of autoignition can vary significantly as CCD coverage in the chamber increases. In order to better characterize and quantify the influence of CCDs, a numerical methodology has been developed which permits calculation of the crank-angle resolved local temperature profile at the surface of a layer of combustion chamber deposits. This unique predictor-corrector methodology relies on experimental measurement of instantaneous temperature underneath the layer, i.e., at the metal-CCD interface, and known deposit layer thickness. A numerical method for validation of these calculations has also been devised. The resultant crank-angle resolved CCD surface temperature and heat flux profiles both on top and under the CCD layer provide valuable insight into the near wall phenomena, and shed light on the interplay between the dynamics of the heat transfer process and HCCI burn rates.

scholarly journals An Analysis of Support Mechanisms for New CHPs: The Case of Poland

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5635
Author(s):  
Krzysztof Zamasz ◽  
Radosław Kapłan ◽  
Przemysław Kaszyński ◽  
Piotr W. Saługa
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
High Efficiency ◽  
Global Scale ◽  
The European Union ◽  
Capacity Market ◽  
Low Emission ◽  
The Social ◽  
Pros And Cons ◽  
Increasing Demand

The increasing demand for energy on a global scale, as well as the social pressure related to counteracting the effects of climate change, has created favourable conditions for the transformation of energy sectors towards the possession of low-emission generation sources. This situation, however, requires investment actions in order to modernise the existing power and CHP (Combined Heat and Power) plants and construct new units. These issues, together with the climate and energy policy pursued by the European Union, are the main reasons for the emergence of various governmental mechanisms supporting the replacement of old coal power units with highly efficient cogeneration units based on gas turbines and other units. The support may take different forms. This article discusses two examples of mechanisms available on the Polish market, i.e., (i) the capacity market and (ii) promoting electricity from high-efficiency cogeneration in the form of individual cogeneration premium. The purpose and novelty of the analysis was to identify the pros and cons and the key parameters which determine the advantage of a given mechanism. Both these mechanisms have been characterised and then compared via the example of a planned cogeneration gas unit (an open cycle gas turbine—OCGT). This assessment was made using discount methods based on the FCFF (free cashflow to company) approach. The analysis did not bring forward an unequivocal answer as to the absolute advantage of any of the solutions, but it was able to point out significant problems related to their practical use.

IGNITION CONDITIONS OF A SINGLE BORON PARTICLE IN HOT GAS FLOW

2020 ◽  
Author(s):  
G. V. Ermolaev ◽  
◽  
A. V. Zaitsev ◽  
Keyword(s):  
Oxygen Concentration ◽  
Gas Flow ◽  
Flame Temperature ◽  
Combustion Process ◽  
Experimental Studies ◽  
Gas Temperature ◽  
Hot Gas ◽  
Combustion Models ◽  
Boron Particle ◽  
Boron Particles

The basic experimental studies on boron combustion are done with the same general scheme of the experiment. Boron particles are injected into flat-flame burner products with the help of the transporting jet of cold nitrogen. Boron particle combustion process is registered with a number of optical methods. It is proposed that boron particle is injected into the main hot gas flow instantly, combustion takes place at the flame temperature and predefined oxygen concentration, and the influence of the transporting cold nitrogen jet is ignored. Recent combustion models are based mostly on this type of experiments and characterized with high complexity and low prediction level. In our study, we reconstruct the particle injection conditions for several basic experimental papers. It is shown that in all experimental setups, ignition, combustion, and even total particle burnout take place in the wake of the cold nitrogen jet. This zone is characterized with a much lower gas temperature and oxygen concentration than the main flat burner flow. The total temperature decrease can be about several hundred degrees, oxygen concentration can be 30%-50% lower than that used in the previous analysis of the experimental results. The temperatures of ignition and transition to the second stage of combustion are found with the help of the test particle trajectory and temperature tracking. It is shown that analysis of the influence of boron particles injection on gas temperature and oxygen concentration is mandatory for the development of future combustion models.

scholarly journals Study of combustion process with jet-ignition of propane-air mixtures

2015 ◽  
Vol 63 (2) ◽  
pp. 533-543 ◽  
Author(s):  
B. Sendyka ◽  
W. Mitianiec ◽  
M. Noga
Keyword(s):  
Combustion Chamber ◽  
Combustion Process ◽  
Experimental Studies ◽  
Front Propagation ◽  
Schlieren Method ◽  
Cfd Simulations ◽  
Hot Gas ◽  
Spark Plug ◽  
Pressure Increment ◽  
The Mathematical Model

Abstract The paper presents the study of combustion process of a homogenous lean propane-air mixture in the cylindrical combustion chamber ignited by a hot gas jet from the pre-ignition chamber. A rich propane-air mixture in the pre-chamber is ignited by the spark plug and the exhaust gasses flow from the chamber trough the holes in the wall. The mathematical model of gas exchange and energy balance in chambers with a laminar finite-rate model taking into account the two-step Arrhenius chemical kinetics is presented. The work presents results of thermodynamic parameters of the charge obtained in CFD simulations in Fluent and Kiva3v for three configurations: with one hole in the wall of the ignition chamber, with three holes and without an ignition chamber. Modelling and simulation have shown faster burning of the mixture for jet ignition with three holes of the pre-chamber. The results of simulations were verified by experimental studies in the combustion chamber of the same geometry by the Schlieren method. The work presents flame front propagation, pressure traces and pressure increment speed for two mixtures with a different equivalence fuel-air ratio. Experimental results proved the simulation observation of faster flame propagation in the main chamber with three holes

CFD simulation-based predesign of an advanced gas-diesel combustion concept

2021 ◽  
pp. 146808742110350
Author(s):  
Hubert Winter ◽  
Kevin Aßmus ◽  
Christoph Redtenbacher ◽  
Dimitar Dimitrov ◽  
Andreas Wimmer
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Cfd Simulation ◽  
Combustion Process ◽  
Diesel Combustion ◽  
Virtual Design ◽  
Engine Operation ◽  
Low Emission ◽  
Methane Slip

The greenhouse gas saving potential of using gaseous fuels with high methane content (e.g. natural gas) in internal combustion engines instead of conventional liquid fossil fuels (e.g. petrol, diesel) is considerable due to the comparatively low emission of carbon dioxide resulting from the low C/H ratio of methane. However, to fully exploit this potential, it is of utmost importance to keep methane slip at a very low level. In contrast to mixture aspirated gas engines and diesel-gas engines, the gas-diesel combustion concept avoids methane slip nearly completely since the gaseous fuel is directly injected into the combustion chamber at the end of the high-pressure phase of the engine cycle, resulting in mixing-controlled combustion with low emission of unburned hydrocarbons. An advanced high-speed large engine concept based on the gas-diesel combustion process was developed. An effective and reliable virtual design methodology was applied during the development of the concept. The methodology comprehensively combines 3D CFD and 1D simulation tools in the combustion concept predesign phase with experiments on a single-cylinder research engine in the concept validation phase. A major challenge in the virtual design of this dual fuel combustion process is the large number of degrees of freedom that result in particular from the use of a fully flexible combined gas/diesel injector. This paper describes in detail the role of 3D CFD simulation in this approach, which allows precise prediction of the optimal geometries and operating strategies for high-efficiency and low-emission engine operation.

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