Transient heat conduction and hotspot development prediction in a flaking roll with revolving heat flux and convection boundary conditions

P. P. Singh, D. E. Maier

Research output: Contribution to journalArticle

Abstract

In the oilseed crushing industry, flaking rolls sometimes develop hotspots that cause high thermal stresses. Soybean flakes on contact with hotspots crumble to powder, which is unsuitable for oil extraction. Transient heat conduction equations with revolving boundary conditions were solved using the finite element method. Simulations demonstrated that hotspots arise due to heat flow in three dimensions from the source toward the roll ends and the curved surface. An estimated heat flux value of 56 kW/m2 yielded surface temperature values near observed values. Perturbations performed to the base values showed that a 10% increase in thermal conductivity caused a 6-8% reduction in peak thermal gradient, whereas a 20% increase in heat-transfer coefficient caused less than 2% reduction in peak thermal gradient. Therefore, thermal conductivity is a more sensitive parameter affecting thermal gradients than the heat-transfer coefficient. A small change in heat-transfer coefficient caused by aspirating air through the flake outlet of the roll stands would not cause a significant reduction in temperature and thermal gradients in rolls. The higher thermal gradients observed near the outer surface of rolls suggest that casting rolls with subsurface layers of higher thermal conductivity would make rolls less prone to forming hotspots.

Original languageEnglish (US)
Pages (from-to)787-792
Number of pages6
JournalJAOCS, Journal of the American Oil Chemists' Society
Volume78
Issue number8
DOIs
StatePublished - Aug 2001
Externally publishedYes

Keywords

  • Convection
  • Finite element
  • Flaking
  • Heat flux
  • Hotspots
  • Revolving boundary condition
  • Transient heat conduction

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Organic Chemistry

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