Horizontal Plate, Heated Face Up — Isothermal
Calculates the average convective heat transfer coefficient and total heat rate for a horizontal plate whose heated surface faces upward (equivalently, a cooled surface facing downward). Buoyant fluid rises freely away from the surface, so this orientation convects more strongly than the heated-down case.
Characteristic Length
For a horizontal plate the characteristic length is the area-to-perimeter ratio:
Lc=PA=2(L+W)LWRayleigh Number
Properties are evaluated at the film temperature Tf=(Ts+T∞)/2:
Ra=ν2gβ(Ts−T∞)Lc3PrNusselt Number
Nu=0.54Ra1/4(104≤Ra≤107) Nu=0.15Ra1/3(107<Ra≤1011)Heat Transfer Coefficient and Heat Rate
h=LcNu⋅k,Q=hA(Ts−T∞),A=LWReferences
- Lloyd, J. R. and Moran, W. R., Natural Convection Adjacent to Horizontal Surfaces of Various Planforms, ASME Pap. 74-WA/HT-66.
- Fujii, T. and Imura, H., Int. J. Heat Mass Transfer, vol. 15, p. 755, 1972.
- Incropera, F. P. and DeWitt, D. P., Fundamentals of Heat and Mass Transfer.