Solve the following:
Q: A warehouse is to be designed for keeping perishable foods cool prior to transportation to grocery stores. The warehouse has an effective surface area of 20,000 ft2 exposed to an ambient air temperature of 90°F. The warehouse wall insulation (k = 0.1 Btu/(h ft°F)) is 3 in. thick. Determine the rate at which heat must be removed (Btu/h) from the warehouse to maintain the food at 40°F.
GIVEN
Cooled warehouse
Effective area (A) = 20,000 ft2
Temperatures
Outside air = 90°F and food inside = 40°F
Thickness of wall insulation (L) = 3 in. = 0.25 ft
Thermal conductivity of insulation (k) = 0.1 Btu/(h ft°F)
ASSUMPTIONS
One dimensional, steady state heat flow
The food and the air inside the warehouse are at the same temperature
The thermal resistance of the wall is approximately equal to the thermal resistance of the wall insulationalone
