A 30 ft by 40 ft classroom with 8 ft high ceilings will have an ambient lighting target illuminance of 70 fc at a work plane that is 28 in. above the floor. It is anticipated that the ceiling reflectance is 0.5 and the average wall reflectance is about 0.3. The space will be illuminated with recessed lay-in 2 ft x 4 ft open troffer luminaires with four lamps. The initial output of the fluorescent lamps is 2850 lumen. The light loss factor will be assumed to be 0.7. Use the zonal cavity method to determine the minimum number of luminaires required to provide uniform illumination in the space.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Ahouse has the following electrical appliance usage (1) single 40w lamp used for 4 hours per day (2) single 60w fan used for 12 hours per day (3) single 200w refrigerator that runs 24 hours per day with compressor run 12 hours and off 12 hours find the solar power inverter size in watt with correction factor of 1.25.

Agas mixture consists of 8 kmol of h2 and 2 kmol of n2. determine the mass of each gas and the apparent gas constant of the mixture.