Cylindrical dry-bulb and wet-bulb thermometers are installed in a large-diameter duct to obtain the temperature T_∞, and the relative humidity ϕx of moist air flowing through the duct at a velocity V. The dry-bulb thermometer has a bare glass surface of diameter Ddb and emissivity Bg. The wet-bulb thermometer is covered with a thin wick that is saturated with water flowing continuously by capillary action from a bottom reservoir. Its diameter and emissivity are designated as D_wb and ε_w- The duct inside surface is at a known temperature T_s which is less than T_∞. Develop expressions that may be used to obtain T_∞ and ϕx from knowledge of the dry-bulb and wet-bulb temperatures T_db and T_wb and the foregoing parameters. Determine T_∞ and ϕ_∞ when T_db = 45°C, T_wb = 25°C, T_s = 35°C, P = 1 atm. V = 5 m/s, D_db = 3 mm, D_wb = 4 mm, and ε_g = ε_w = 0.95. As a first approximation, evaluate the dry- and wet-bulb air properties at 45 and 25°C, respectively.