The black grille on the back of a refrigerator has a surface temperature of 35¬¨¬®‚Äö√†√ªC with a surface area of 1 m2. Heat transfer to the room air at 20¬¨¬®‚Äö√†√ªC takes place with convective heat transfer coefficient of 15 W/Km^2. How much energy is removed during 15 minutes of operation?$

The black grille on the back of a refrigerator has a surface temperatu

1.	The black grille on the back of a refrigerator has a surface temperature of 35¬¨¬®‚Äö√†√ªC with a surface area of 1 m2. Heat transfer to the room air at 20¬¨¬®‚Äö√†√ªC takes place with convective heat transfer coefficient of 15 W/Km^2. How much energy is removed during 15 minutes of operation?$
A.	202.5 kJ
B.	212.5 kJ
C.	222.5 kJ
D.	232.5 kJ
Answer» B. 212.5 kJ

Discussion

No Comment Found

Related MCQs

A radiant heating lamp has a surface temperature of 1000 K with ε = 0.8. How large a surface area is needed to provide 250 W of radiation heat transfer?
A 2 m2 window has a surface temperature of 15°C and the outside wind is blowing air at 2°C across it with a convection heat transfer coefficient of h = 125 W/m2K. What is the total heat transfer loss?
Find the rate of conduction heat transfer through a 1.5 cm thick hardwood board, k = 0.16 W/m K, with a temperature difference between the two sides of 20°C.
A water-heater is covered up with insulation boards over a total surface area of 3 m2. The inside board surface is at 75°C and the outside surface is at 20°C and the board material has a conductivity of 0.08 W/m K. How thick a board should it be to limit the heat transfer loss to 200 W ?
A radiant heat lamp is a rod, 0.5 m long, 0.5 cm in diameter, through which 400 W of electric energy is deposited. Assume the surface emissivity to be 0.9 and neglecting incoming radiation, find the rod surface temperature?
A burning wood in the fireplace has a surface temperature of 450°C. Assume the emissivity to be 1 and find the radiant emission of energy per unit area.
As the car slows down, the brake shoe and steel drum continuously absorbs 25 W. Assume a total outside surface area of 0.1 m2 with a convective heat transfer coefficient of 10 W/Km2 to the air at 20°C. How hot does the outside brake and drum surface become when steady conditions are reached?
A small light bulb (25 W) inside a refrigerator is kept on and 50 W of energy from the outside seeps into the refrigerated space. How much of temperature difference to the ambient(at 20°C) must the refrigerator have in its heat exchanger having an area of 1 m2 and heat transfer coefficient of 15 W/Km2 to reject the leak of energy.
The black grille on the back of a refrigerator has a surface temperature of 35°C with a surface area of 1 m2. Heat transfer to the room air at 20°C takes place with convective heat transfer coefficient of 15 W/Km^2. How much energy is removed during 15 minutes of operation?
A large heat exchanger transfers a total of 100 MW. Assume the wall separating steam and seawater is 4 mm of steel, conductivity 15 W/m K and that a maximum of 5°C difference between the two fluids is allowed. Find the required minimum area for the heat transfer.

Discussion

No Comment Found

Related MCQs

Reply to Comment