scholarly journals Simulation of Combustion Air Flow in the Gasification Biomass Boiler

2018 ◽  
Vol 168 ◽  
pp. 02015 ◽  
Author(s):  
Marek Patsch ◽  
Peter Pilát
Keyword(s):  
Heat Source ◽  
Air Flow ◽  
Biomass Combustion ◽  
Air Distribution ◽  
Combustion Chambers ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Biomass Boiler ◽  
Certification Tests ◽  
Experimental Heat

The article deals with the optimization of biomass combustion in a small heat source by means of an optimal distribution of combustion air. The uneven distribution of combustion air has been observed in certification tests and in real operation of used heat source and it has an influence on uneven combustion of biomass in the gasification chamber, on increase emissions and combustion losses. At this stage of the research, optimization of the combustion air distribution is performed by CFD simulations, which will be later verified by PIV measuring of the velocity fields in gasification and combustion chambers of the experimental heat source. CFD simulations and subsequent PIV measurements on the experimental device are realized without real combustion, only the air flow in the empty gasification chamber and in the combustion chamber is investigated. This approach has been chosen to simplify calculations and experiments, and on the assumption that when the combustion air distribution is optimal in empty chambers, it will be optimal even during real combustion. The primary air flow in the gasification chamber is in real operation affected by the size and shape of the inserted biomass and its placement in chamber and this effect is accidental and difficult to verifiable.

scholarly journals COMPARISON OF MATHEMATICAL MODELS FOR HEAT EXCHANGERS OF UNCONVENTIONAL CHP UNITS

2015 ◽  
Vol 55 (4) ◽  
pp. 223 ◽  
Author(s):  
Peter Durcansky
Keyword(s):  
Energy Source ◽  
Heat Exchanger ◽  
Heat Source ◽  
Heat Exchangers ◽  
Primary Energy ◽  
Biomass Combustion ◽  
Cfd Simulations ◽  
Correct Operation ◽  
Hot Air ◽  
Working Medium

An unconventional CHP unit with a hot air engine is designed as the primary energy source with fuel in the form of biomass. The heat source is a furnace designed for combustion of biomass, whether in the form of wood logs or pellets. The transport of energy generated by the biomass combustion to the working medium of a hot-air engine is ensured by a special heat exchanger connected to this resource. The correct operation of the hot-air engine is largely dependent on an appropriate design of the exchanger. The paper deals with the calculation of the heat exchanger for the applications<br />mentioned, using criterion equations, and based on CFD simulations.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

scholarly journals A three-dimensional theory of wind pumping

1991 ◽  
Vol 37 (125) ◽  
pp. 89-96 ◽  
Author(s):  
Garry K. C. Clarke ◽  
Edwin D. Waddington
Keyword(s):  
Heat Source ◽  
Surface Pressure ◽  
Air Flow ◽  
Pressure Fluctuations ◽  
Normal Component ◽  
Three Dimensional ◽  
Lower Atmosphere ◽  
Dimensional Theory ◽  
Theoretical Formulation ◽  
Near Surface

AbstractQuantitative understanding of the processes that couple the lower atmosphere to the upper surface of ice sheets is necessary for interpreting ice-core records. Of special interest are those processes that involve the exchange of energy or atmospheric constituents. One such process, wind pumping, entails both possibilities and provides a possible mechanism for converting atmospheric kinetic energy into a near-surface heat source within the firn layer. The essential idea is that temporal and spatial variations in surface air pressure, resulting from air motion, can diffuse into permeable firn by conventional Darcy flow. Viscous friction between moving air and the solid firn matrix leads to energy dissipation in the firn that is equivalent to a volumetric heat source.Initial theoretical work on wind pumping was aimed at explaining anomalous near-surface temperatures measured at sites on Agassiz Ice Cap, Arctic Canada. A conclusion of this preliminary work was that, under highly favourable conditions, anomalous warming of as much as 2°C was possible. Subsequent efforts to confirm wind-pumping predictions suggest that our initial estimates of the penetration depth for pressure fluctuations were optimistic. These observations point to a deficiency of the initial theoretical formulation — the surface-pressure forcing was assumed to vary temporally, but not spatially. Thus, within the firn there was only a surface-normal component of air flow. The purpose of the present contribution is to advance a three-dimensional theory of wind pumping in which air flow is driven by both spatial and temporal fluctuations in surface pressure. Conclusions of the three-dimensional analysis are that the penetration of pressure fluctuations, and hence the thickness of the zone of frictional interaction between air and permeable firn, is related to both the frequency of the pressure fluctuations and to the spatial coherence length of turbulence cells near the firn surface.

CFD Simulations of Acoustic Wave Phenomena in Combustion Chambers

2006 ◽  
pp. 89-94
Author(s):  
Venkateswaran Sankaran ◽  
Guoping Xia ◽  
Matthew Ellis ◽  
Charles Merkle
Keyword(s):  
Acoustic Wave ◽  
Combustion Chambers ◽  
Cfd Simulations ◽  
Wave Phenomena

scholarly journals DESIGNING A SMALL CLIMATE CHAMBER TO CHARACTERIZE PEOPLE AS A SOURCE OF DETERIORATION OF INDOOR AIR QUALITY BY RESPIRATION

2019 ◽  
Vol 7 ◽  
pp. 954-959 ◽  
Author(s):  
Detelin Ganchev Markov ◽  
Sergey Mijorski ◽  
Peter Stankov ◽  
Iskra Simova ◽  
Radositna A. Angelova ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Water Vapor ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Carbon Dioxide Concentration ◽  
Air Distribution ◽  
Vapor Concentration ◽  
Cfd Simulations ◽  
Climate Chamber

: People are one of the sources for deterioration of the indoor air quality. They worsen indoor air quality by their presence (respiration, bio-effluents), activities and habits. Through respiration, people decrease the oxygen concentration in the air of the occupied space and increase carbon dioxide and water vapor concentration in the indoor air as well as its temperature. The goal of the AIRMEN project is to find out if the rate of consumption of oxygen and emission of carbon dioxide (and water vapor) by people depends on the indoor air temperature as well as carbon dioxide concentration in the inhaled air. In order to achieve this goal a small climate chamber must be designed and constructed which allows for controlling and measuring both inflow and exposure parameters as well as for measuring outflow parameters. The principal goal of this paper is to present some important details, obtained by CFD simulations, from the design process of the climate chamber which precondition the air distribution in the chamber and hence the exposure parameters.

scholarly journals Fill ventilation of heated corn grain

2020 ◽  
pp. 74-77
Author(s):  
Mikhail Gennadievich Zagoruyko ◽  
Sergey Anatolyevich Pavlov
Keyword(s):  
Experimental Data ◽  
Distribution System ◽  
Air Flow ◽  
Air Distribution ◽  
The Dead ◽  
Over Time ◽  
Corn Grain

The grain masses of the first and subsequent batches, the equivalent coefficient of the dead gap of the air distribution system are calculated, the expressions for calculating the air flow for these batches and the experimental data on the change in moisture and temperature of the grain over time are given.

scholarly journals A study of the interaction of a travelling shock wave with a solid-propellant rocket motor head end

2021 ◽  
Author(s):  
Robert Elian Feteanu
Keyword(s):  
Shock Wave ◽  
Rocket Motor ◽  
Combustion Chambers ◽  
Cfd Simulations ◽  
Radial Wave ◽  
Flow Models ◽  
Numerical Studies ◽  
Solid Propellant Rocket ◽  
Wave Development ◽  
Solid Rocket

Experimental and numerical studies have been undertaken to examine various aspects pertaining to the interaction of an incident travelling shock wave with a solid rocket motor's head end (forward section), in order to identify any potential gasdynamic mechanism of wave reinforcement pertinent to combustion instability behaviour in these motors. A cold-flow experiment, based on a shock tube scheme tailored to the present application, has proved to be useful in providing information surrounding the interaction process. Both experimental and numerical results (CFD simulations) confirm the existence of substantial transient radial wave development superimposed on the base reflected axial shock wave. These results illustrate the potential weakness of one-dimensional flow models for certain engineering applications, where important multidimensional phenomena, such as those observed in this work, may not be captured. By analogy to actual propulsion system combustion chambers, the transverse wave activity is potentially a factor in supporting an augmentation of the local combustion rate in the head-end region of a rocket motor combustor.

scholarly journals OPTIMALIZATION OF AFTERBURNER CHANNEL IN BIOMASS BOILER USING CFD ANALYSIS

2016 ◽  
Vol 56 (5) ◽  
pp. 379-387 ◽  
Author(s):  
Jiří Pospíšil ◽  
Martin Lisý ◽  
Michal Špiláček
Keyword(s):  
Cross Sections ◽  
Flue Gas ◽  
Air Distribution ◽  
Cfd Analysis ◽  
Mixing Process ◽  
Rectangular Duct ◽  
Biomass Boiler ◽  
Cross Section Area ◽  
Section Area ◽  
Secondary Air

This contribution presents the results of parametrical studies focused on the mixing process in a small rectangular duct within a biomass boiler. The first study investigates the influence of a local narrowing located in the central part of the duct. This narrowing works as an orifice with very simple rectangular geometry. Four different free cross sections of the orifice were considered in the center of the duct, namely 100%, 70%, 50%, 30% of free cross section area in the duct. The second study is focused on the investigation of the influence of secondary air distribution pipe diameter on the mixing process in a flue gas duct without a narrowing.

PIV measurements and CFD simulations of the particle-scale flow distribution in a packed bed

2019 ◽  
Vol 374 ◽  
pp. 189-200 ◽  
Author(s):  
Abhijeet H. Thaker ◽  
G.M. Karthik ◽  
Vivek V. Buwa
Keyword(s):  
Flow Distribution ◽  
Packed Bed ◽  
Cfd Simulations ◽  
Piv Measurements
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