Abstract

Mass transfer by sublimation from 4-in-diam naphthalene disks to the stagnation regions of impinging jets of air was calibrated with heat transfer by convection in an identical configuration. Within the limits of the experimental reproducibility, all results were brought into a single correlation using Colburn’s formulation of the heat-mass analogy. The calibration was then employed to obtain mean coefficients of heat transfer on disks with free edges. This part of the investigation was performed using two sorts of air streams; namely, a 10-in-diam jet discharging freely into the atmosphere and a 5-ft-diam stream in a closed throat of a wind tunnel. The air speeds ranged from 22 to 293 fps, and the disks, made of naphthalene or of paradichlorobenzene, were 2.25 and 4 in. diam. The results of this part of the investigation may be represented by the equation
j(GDpμf)=1.08
with a probable error of ±3 per cent. Including Powell’s work on evaporation of water from disks, the equation covers a range of Reynolds number from 2000 to 600,000 with a maximum deviation of about ±10 per cent from the experimental points. The results of this work possibly may be of some general interest with regard to heat transfer at the stagnation region of a surface of revolution and perhaps may be of some use in dew point or water-content instrumentation.
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