Our students perform a laboratory experiment to determine mass transfer from a wet paper towel experiencing forced convection and irradiation from radiant lamps. For the values of T? and Twb prescribed on the sketch, the towel temperature was found to be Ts = 310 K. In addition flat-plate correlations yielded average heat and mass transfer convection coefficients of h = 28.7 W/m2 ? K and hm = 0.027 m/s, respectively. The towel has dimensions of 92.5 mm x 92.5 mm and is diffuse and gray with an emissivity of 0.96.

(a) From the foregoing results, determine the vapor densities, pA,s and pA,? the evaporation rate, nA (kg/s), and the net rate of radiation transfer to the towel qrad (W).

(b) Using results from part (a) and assuming that the irradiation G is uniform over the towel determine the emissive power E, the irradiation G, and the radiosity J.

Radiant lamps Air T- 290 K Water-soaked paper towel - Insulation Tut = 290 K KANGAR