Consider the physical system of Problem 7.119 (a series of water-filled trays heated radiatively), but under operating conditions for which each tray is 0.25 m long by 1 m wide and is uniformly irradiated, with G = 10⁴ W/m². Dry air at T_∞ = 300 K continues to flow over the trays at a velocity of 15 m/s

(a) What is the rate of water loss (kg/s) from the first, third, and fourth trays?

(b) Estimate the temperature of the water in each of the designated trays. 

Data From Problem 7.119

A series of water-filled trays, each 222 mm long, experiences  an evaporative drying process. Dry air at T_∞ = 300 K flows over the trays with a velocity of 15 m/s, while radiant heaters maintain the surface temperature  at T_s = 330 K.

(a) What is the evaporative flux (kg/s · m²) at a distance 1 m from the leading edge?

(b) What is the irradiation (W/m²) that should be supplied to the tray surface at this location to maintain the water temperature at 330 K?

(c) Assuming the water temperature is uniform over the tray at this location, what is the evaporation rate (kg/s · m) from the tray per unit width of the tray?

(d) What irradiation should be applied to each of the first four trays such that the corresponding evaporation rates are identical to that found in part (c)?

Transcribed Image Text:

➤X Dry air Иса То -Radiant heaters -Water-filled tray 1 m -Ts