A laboratory experiment involves simultaneous heat and mass transfer from a water-soaked towel experiencing irradiation from a bank of radiant lamps and parallel flow of air over its surface. Using a convection correlation to be introduced in Chapter 7, the average heat transfer convection coefficient is estimated to be h = 28.7 W/m2 ∙ K. Assume that the Radiative propel1ies of the towel are those of water, for which a = ε= 0.96, and that the surroundings are at 300 K.

(a) Determine the rate at which water evaporates from the towel nA (kg/s).

(b) Perform an energy balance on the towel to determine the net rate of radiation transfer, qrad (W), to the towel. Determine the irradiation G (W/m2).

Radiant lamps Irradiation on II towel, G (Wim?) 111 1tt T= 290 K, 0.= 0 Water-soaked paper towel. T = 310 K, A, = 92.5 mm x 92.5 mm Air Insulation