Modeling issue in glass production plants. Radiative heat ... · PDF fileRadiative heat transfer analysis for the flue gas recirculation technique ... and gas turbine combustion ...

Modeling issue in glass production plants. Radiative heat transfer analysis for the flue gas recirculation technique

and combustion analysis

Santo Cogliandro, Carlo Cravero

Università di Genova

LIFE 12 ENV/IT/001020 - PRIMEGLASS

Scientific Conference

Università di Genova – Savona Campus – January 24th 2017

The CFD group @ DIME

LIFE12 ENV/IT/001020 - PRIME GLASS



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Prof. W.N. Dawes - CFD Lab. Cambridge University (UK)

Prof. S. Cant - CFD Lab. Cambridge University (UK)

Prof. P.Orkwis - AEEM Cincinnati University (USA)

Prof. M. Turner - AEEM Cincinnati University (USA)

Dr. A. Merchant - GTLab MIT (USA)

Prof. G. Gerolymos - LEMFI Universitè Paris VI (Fr)

Industrial collaborations

Ansaldo Energia Ansaldo Ricerche Ansaldo Nucleare

Piaggio Aerospace ABB Termomeccanica Pompe Termomeccanica Compressori

Johnson Electric GEA Srl Mares Spa Muds Srl Mavel Srl Stara Glass Spa SSV

Research collaborationsstarting 1992 …




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Long term experience on CFD platform

development and application to industrial

problems or product development

Several CFD platforms available at source

code level from geometry management to

post processing (mainly for

turbomachinery analysis or design)




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From turbomachinery ….

….toward industrial components… …… to glass production plants

17stages axial compressor 3D analysis

….through aerospace …

and gas turbine combustion….

NAV3D CFD suite McUnNEWT code




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Glass production plant and strategic gas recirculation technology:

modelling and application issues using CFD and lower order models

2) Regenerative chambers – CFD and lower order

- a CFD based simulation process to optimise

gas recirculation system

3) Combustion - CFD

- prediction of design trends and effects of

operating parameters

1) Radiation and Infrared emission – CFD and lower order

- need for gas emission model

- use of video camera for combusion monitoring

….. and of course the piping !




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RADIATION THEORY




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Heat exchange

Conduction Molecular energy transport through a solid or a fluid in quiet

Convection Energy exchange between a solid and a fluid in motion

Radiation Transport of energy by means of electromagnetic radiation




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Every form of matter with a temperature (T) above absolute zero emits radiation according to its temperature. This is called characteristic radiation. The cause of this is the internal mechanical movement of molecules. Since the molecule movement represents charge displacement, electromagnetic radiation (photon particles) is emitted. These photons move at the speed of light and behave according to the known optical principles.

The energy emitted depends on the temperature, the wavelength and the characteristics of the material.

The transmission of energy does not need a medium but it is transmitted also in vacuum




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The bodies can exchange heat

through electromagnetic

radiation.

It is the only form of energy

exchange that can take place

in a vacuum.




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The emission from an opaque solid or

by a liquid is a surface phenomenon.

For a solid opaque and a liquid, the

emission is originated by a layer

surface material with a thickness

about 1 micron

The emission of radiation by a gas or

a solid semi-transparent It is of the

volumetric type




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The theory is based on four well-known radiation

laws :

1. Planck’s law of radiation of ideal black body,

2. the Stefan–Boltzmann law.

3. the law about the relation between

emission and absorption found by Kirchhoff

3. Wien displacement law




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Many bodies, however, emit less radiation atthe same temperature. The relation betweenthe real emissive power and that of ablackbody is known as emissivity and can be amaximum of 1 (body corresponds to the idealblackbody) and a minimum of 0. Bodies withemissivity less than 1 are called gray bodies.Bodies where emissivity is also dependent onwavelength are called non-gray bodies. Theemissivity coefficient e is non-dimensional;it depends on the wavelength, on thetemperature and the surface texture of thebody.




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The radiation incident on each body can be absorbed, reflected or

trasmitted

The relation between emission and absorption was found by Kirchhoff

Therefore for an opaque body ()




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The emissivity coefficient is generally determined experimentally

the temperature dependence of emissivity




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the wavelength dependence of emissivity




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The wavelength dependence of reflectivity




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The previous discussion is

not applicable to gases that

are non-gray body. Most

combustion processes result

in the formation of carbon

dioxide, water vapor and

carbon monoxide; thus a

knowledge of their spectra is

likely to be directly applicable

to the prediction of the

radiation from a burner. The

spectral radiance in an

emission band cannot

exceed the spectral radiance

of a blackbody at the same

wavelength and temperature

Emission band of H2O,

CO2 and CO at 2000 K




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RADIATION MODELLING




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One would expect fromKirchoff’s law that goodemitters are good absorbersand that non emission bandresults: but in a flame theemission band is broader thanthe corresponding absorptionband and it is shifted towardlonger wavelength by the highertemperature and pressure inthe flame

Infrared emission from aBunsen flame




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we can simulate for a solid opaque body the total emitted energy equal to

• in case of a gray body by using the Stefan–Boltzmann law with the multiplication factor (emissivity)

in case of a non-gray body by using an average multiplication factor

(emissivity) in selected bands for selective body




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The magnitude of the thermal power q [W] exchanged by radiation between two or more bodies depends on the orientation of the reciprocal surfaces, by their radiative properties and from their temperatures. it is necessary to introduce the concept of view factor to calculate q

The view factor between the surface area i and a j is the fraction of energyissued by the i that directly affects j.

The view factor is a purely geometric size and depends only on the mutual position of the surfaces.




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The view factor




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In case of a gas mixture by using a total emissivity for each gas that simulates the behavior of the gas as a gray body.

Several studies have led to the determination of the following tables according to Temperature, the partial pressure of the gas and the optical path. Here is an example for the two more significant gas CO2 and H2O




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•H2O total emissivity vs

Temperature as a function of partial pressure and the optical path

•HOTTEL CHART




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•CO2 total emissivity vs Temperature

as a function of partial pressure and the optical path

•HOTTEL CHART




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GAS EMISSIVITY MODEL VALIDATION




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To calculate analytically the gas emissivity

we have developed a 4 degree polynomial curve and we compared it

with data derived from literature

The total gas emissivity is

Where

The radiant net flux between gas and body is




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Calculated CO2 emissivity:

UNIGE University of Genova

SLW: Spectral Line Wave

EWBM: Exponential WaveBand Model

Farag & Hottel : experimental data




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Calculated H20 emissivity:

UNIGE University of Genova

SLW: Spectral Line Wave

EWBM: Exponential WaveBand Model

Farag & Hottel : experimental data




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THE MEASUREMENT SYSTEM




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THE MEASUREMENT SYSTEM




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TARGET: WHAT DO WE WANT TO MEASURE?




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IR image in two different bands

(4.5 micron and 3.9 micron)

4.5 micron band 3.9 micron band




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1. TEMPERATURE OF GAS

2. TEMPERATURE OF GLASS

3. CO2 AND CO QUALITATIVE DISTRIBUTION




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atmospheric windows




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DETECTOR




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DetectorsThe construction of a thermal imaging camera is similar to the construction of a digital video camera. There is a lens, a detector, some electronics to process the signal from the detector and a viewfinder or screen for the user to see the image produced by the camera. The detectors used for the Gas Detection cameras are quantum detectors that require cooling to cryogenic temperatures(around 70K or -203°C). The MW camera uses an InSb detector and the LW camera a QWIP detector.




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PLUME TEMPERATUREλ = 1 MICRON

GLASS TEMPERATUREλ = 3.9 MICRON




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CO2 DISTRIBUTIONλ = 4.3 MICRON

(InSb with a filter)

CO DISTRIBUTIONλ = 4.5 MICRON

(InSb with a filter)




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POST PROCESSING AND PROCESS MONITORING




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NIR thermography at 1 micron (temperature measurements) single frame




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T max, average T, flame surfaceand geometrical barycenter




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T max, average T, flame surfaceand geometrical barycenter




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T max, average T, flame surfaceand geometrical baricenter




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QUANTITATIVE POST PROCESSING FROM VIDEO ACQUISITION OF THE TEMPERATURE PATTERN

BARICENTER EXTENTION (AREA) MAX AND AVERAGE TEMPERATURE

An example of flame fluctuations of an existing video acquisition….




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POST PROCESSING IS INDIPENDENT FROM SPECTRAL IMAGE

IT IS POSSIBLE TO PROCESS ALSO VISIBLE IMAGES




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CALIBRATION




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IR image after calibration (T)




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AVERAGE TEMPERATURE OF THE FLAME ON 20 FRAME AND FILTER TEMPERATURE

Temperature from 1750 to 1900 K




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STEADY REACTIVE CFD ANALISYS AVERAGED FLAME FROM VIDEO FRAMES

NOTE DIFFERENT FURNACES ……..




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CONCLUSIONSThe radiative heat transfer is crucial and strategic for the combustion simulation and for the recirculating gas technology. A model for gas emissivity has been validated.

The post processing of visual frames from a video camera installed in the furnace can give interesting insights into the flame monitoring

Video camera data can be coupled or integrated with CFD analysis to support the furnace design and monitoring

Modeling issue in glass production plants. Radiative heat ... · PDF fileRadiative heat transfer analysis for the flue gas recirculation technique ... and gas turbine combustion ...

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