Publication detail

Wall heat transfer in gas-fired furnaces: Effect of radiation modelling

VONDÁL, J. HÁJEK, J.

Czech title

Tepelný tok stěnami pece na plynná paliva: vliv modelu radiace

English title

Wall heat transfer in gas-fired furnaces: Effect of radiation modelling

Type

journal article - other

Language

en

Original abstract

The purpose of this work is to study heat transfer to cooled walls in a MW-scale laboratory furnace with a dominating thermal radiation component. Experiment is performed in a specially designed combustion chamber with segmental water-cooled walls and profile of absorbed heat flux is measured along the flame. Non-premixed natural gas flame is stabilized by a guide-vane swirler. The unsteady governing equations of turbulent flow are solved by a finite-volume code with a two-equation k-ε realizable turbulence model, a combination of first-order and second-order upwind schemes and implicit time integration. The coupling of pressure with velocity is treated by SIMPLE (semi-implicit method for pressure-linked equations) algorithm. Radiative heat transfer as the main heat transfer method is modelled with special care by discrete ordinates method and gas absorption coefficient is calculated by two alternatives of WSGGM (weighted sum of grey gases model). The predicted total heat transfer rate is found to depend strongly on method chosen for the computation of mean beam length. The results of numerical simulations show that overall heat transfer in a process furnace can be successfully predicted, while heat flux profile along the flame is more difficult to predict accurately. Good engineering accuracy is nevertheless achievable with reasonable computational resources. The trend of deviations is reported, which is useful for the interpretation of practical predictions of process furnaces (fired heaters).

Czech abstract

Cílem této práce je studium přenosu tepla do stěn spalovací komory s dominujícím přenosem tepla zářením. Experiment je proveden ve speciálně navržené spalovací komoře s vodou chlazenou stěnou rozdělenou do sedmi segmentů, díky čemuž je možné měřit podélný profil tepelného toku do stěn. V komoře je spalován zemní plyn v difúzním plameni stabilizovaným pomocí axiálního, lopatkového vířiče. Naměřená data jsou porovnávána s predikcemi z nestacionární numerické simulace metodou konečných objemů s dvourovnicovým modelem turbulence realizovatelným k-epsilon.

English abstract

The purpose of this work is to study heat transfer to cooled walls in a MW-scale laboratory furnace with a dominating thermal radiation component. Experiment is performed in a specially designed combustion chamber with segmental water-cooled walls and profile of absorbed heat flux is measured along the flame. Non-premixed natural gas flame is stabilized by a guide-vane swirler. The unsteady governing equations of turbulent flow are solved by a finite-volume code with a two-equation k-ε realizable turbulence model, a combination of first-order and second-order upwind schemes and implicit time integration. The coupling of pressure with velocity is treated by SIMPLE (semi-implicit method for pressure-linked equations) algorithm. Radiative heat transfer as the main heat transfer method is modelled with special care by discrete ordinates method and gas absorption coefficient is calculated by two alternatives of WSGGM (weighted sum of grey gases model). The predicted total heat transfer rate is found to depend strongly on method chosen for the computation of mean beam length. The results of numerical simulations show that overall heat transfer in a process furnace can be successfully predicted, while heat flux profile along the flame is more difficult to predict accurately. Good engineering accuracy is nevertheless achievable with reasonable computational resources. The trend of deviations is reported, which is useful for the interpretation of practical predictions of process furnaces (fired heaters).

Keywords in English

gas combustion; wall heat flux; swirling diffusion flame; radiative heat transfer; numerical modelling

RIV year

2015

Released

01.07.2015

Publisher

University of West Bohemia, Univerzitní 8, Pilsen, Czech Republic

Location

Pilsen, Czech Republic

ISSN

1802-680X

Volume

9

Number

1

Pages from–to

67–78

Pages count

12

BIBTEX


@article{BUT115194,
  author="Jiří {Vondál} and Jiří {Hájek},
  title="Wall heat transfer in gas-fired furnaces: Effect of radiation modelling",
  year="2015",
  volume="9",
  number="1",
  month="July",
  pages="67--78",
  publisher="University of West Bohemia, Univerzitní 8, Pilsen, Czech Republic",
  address="Pilsen, Czech Republic",
  issn="1802-680X"
}