On a cold winter day, the outside temperature is –5.0 °C while the interior of a well-insulated garage is maintained at 20.0 °C by an electric heater. Assume the walls have a total area of 75 m2, a thickness of 0.15 m, and a thermal conductivity of 0.042 W/(m · C°). What is the cost to heat the garage for six hours at these temperatures if the cost of electricity is $ 0.11/kWh?
Note: 1 kWh = 3.6 × 106 J.
On a cold winter day, the outside temperature is –5.0 °C while the interior of a...
On a cold winter day, the outside temperature is -20°C and the inside temperature is maintained at 20°C. There is a net heat flow to the outside through the walls, roof, etc., of 25 kW. What is the rate of increase of the entropy of the universe as a result of this heat flow?
A closed box is filled with dry ice at a temperature of -91.3 oC, while the outside temperature is 20.0 oC. The box is cubical, measuring 0.321 m on a side, and the thickness of the walls is 2.99 × 10-2 m. In one day, 3.13 × 106 J of heat is conducted through the six walls. Find the thermal conductivity of the material from which the box is made. Please put answer in: J/(s*m*C degrees)
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On a cold winter day where the outside temperature is -10o C, a heat pump provides 20 kW to heat a house to 20o C. The heat pump has a COPHP of 4 at the maximum power. The next day a storm brings the outside temperature down to −15o C. If the ratio of COPHP and the reversible COPrev for day 1 and day 2 is the same, COPHP for both days is the same, and that the house loses...
1.3 127 5.3 3.(10 pts) A cold storage room (10 m x 10 m x 10 m) is being maintained at 2 °C using a vapor compression refrigeration system that uses R-134a. The evaporator and condenser temperatures are -20 and 40°C, respectively. The walls and ceiling of the storage room is constructed of 15 cm thick concrete (thermal conductivity-1.37 WIm K]) and 4.3 cm thick insulation (thermal conductivity-0.04 W/[m K). The outside insulation surface temperature of the walls (or ceiling)...
need help Problem 5: Suppose a house's walls are 14 cm thick and and have an average thermal conductivity twice that of glass wool. Substance Glass wool Wool Glass Human body Ceramic Wood Air Fatty tissue Styrofoam Thermal conductivity (J/s.m.) 0.042 0.04 0.84 0.2 0.84 0.08-0.16 0.023 0.2 0.010 Otheexperta.com Part (a) Calculate the rate of heat conduction, in watts, through the house's walls. Assume there are no windows or doors. The surface area of the walls is 105 m...
Q3 (6 marks) The window in your room is 2 meters 3 meters. Assuming all other walls are well insulated and that heat loss only occurs through the window, the air in the room is under free convection of 35 W/m2K. The outside surface of the window is 6 °C and the thermal conductivity of window glass is 0.78 W/m K. The thickness of the window glass is 4 mm Calculate the size of the heater that you need in...
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1.3 127 5.3 3.(10 pts) A cold storage room (10 m x 10 m x 10 m) is being maintained at 2 °C using a vapor compression refrigeration system that uses R-134a. The evaporator and condenser temperatures are -20 and 40°C, respectively. The walls and ceiling of the storage room is constructed of 15 cm thick concrete (thermal conductivity-1.37 WIm K]) and 4.3 cm thick insulation (thermal conductivity-0.04 W/[m K). The outside insulation surface temperature of the walls (or ceiling)...