Chapter 4 Transient Heat Conduction4-36 Large brass plates are heated in an oven. The surface temperature of the plates leaving the oven is to be determined. Assumptions1Heat conduction in the plate is one-dimensional since the plate is large relative to its thickness and there is thermal symmetry about the center plane. 3The thermal properties of the plate are constant. 4The heat transfer coefficient is constant and uniform over the entire surface. 5The Fourier number is τ> 0.2 so that the one-term approximate solutions (or the transient temperature charts) are applicable (this assumption will be verified). PropertiesThe properties of brass at room temperature are given to be k = 110 W/m.°C, α= 33.9×10-6m2/s AnalysisThe Biot number for this process is BihLk==°°=(80)( .)().W/m . CmW/m. C200151100 0109 The constants λ1and A1corresponding to this Biot number are, from Table 4-1, 110103910018..and AThe Fourier number is τα××=>−tL26339 101090 40 2(.m / s)(min60 s / min)m)22Plates 25°CFurnace, 700°C Therefore, the one-term approximate solution (or the transient temperature charts) is applicable. Then the
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