On Mon, May 27, 2013 at 4:32 PM, Alan Fletcher <a...@well.com> wrote:
> > And just in case you're wondering how e effects the calculated power > > P = a . e . (T1^4 - T0^4) -- T1 actual, T0 ambient > > a e Tc Tk P > area 18 1.00E-10 0.8 564.1 837.1 38.84 <=== lower "e" > OVER-estimates the power > area 19 1.00E-10 1 496.6 769.6 34.52 > area 20 1.00E-10 0.95 511.7 784.7 35.49 > > > You're right. I did that calculation too. But the reason they're not equal is because they use an effective exponent not equal to 4 when they calculate temperature. It's not clear what that effective exponent would be if the emissivity were set to 0.2, and so we don't know what the effect would be there. And in particular, we don't know what the effect would be if the emissivity depended on wavelength. The literature warns about poor accuracy in such cases.
