Estimate the number of occupants that are seated in an occupied university lecture hall if the room has a floor area of 175 m2, a ceiling height of 4 m, a constant ventilation rate of 1.5 per hour, and the room achieves a steady-state indoor co2 concentration of 1200 ppm. you can assume:
1) the indoor temperature is 22°c;
2) the outdoor co2 concentration is 400 ppm;
3) the building is at sea level;
4) the average per-person co2 emission rate is 21 g/hr;
5) the room is well-mixed; and
6) the ventilation rate, outdoor co2 concentration, occupancy, and indoor emissions are all constant.

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

An air compression refrigeration system is to have an air pressure of 100 psia in the brine tank and an allowable air temperature increase of 60°f for standard vapor compression cycle temperatures of 77 f entering the expansion cylinder and 14 f entering the compression cylinder, calculate the coefficient of performance a. 2.5 b 3.3 c. 4.0 d. 5.0