Optimum Operating Conditions for Pipe Heating and Cooling

Optimum Operating Conditions for Pipe Heating and Cooling Equipment. W. K. Lewis, J. T. Ward, and E. Voss. Ind. Eng. Chem. , 1924, 16 (5), pp 467–46...
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I N 0 USTRIAL A N D ENGINEERING CHEMISTRY

May, 1924

. 12-For approximate calculations of the heat transfer from large smooth surfaces we take a! = 1, /3 = I/*, and KO = 350 in Equation 60. This gives for ideal gases and smooth surfaces We = 0.00246 ApokAt/p

(watts)

(71)

and for air We = 0.0012 A@At/T,,,. (watts) (72) For moderately rough surfaces we may employ Equations 67 and 68, and for very rough surfaces in ideal gases We = 0.010 ApwkAt/p

(watts) (73)

13-The heat transfer in mixtures is covered by the same general equations that apply to liquids and gases. 14-For mixtures of a light with a heavy gas the forced convection a t high velocities over plane surfaces may be greater than in either gas alone. For air, (pc,/k)L/a ( k p / p ) = 0.41 p/Tsvg. Pure hydrogen, ( p c / k ) I / 9 ( k p / p ) = 0.40 p/T,,,. 95% hydrogen 5