Chapter 4, Problem 4.35P

A spherical radiator has a radius of 3ft and emissivity of 0.5. If radiates 6000 Btu/hr of heat at 3000R, what is the temperature of a surface affected by its radiation?

Calculate the amount of heat that is needed to keep the inside temperature at 20 0Cwhen it is at 30C outside in a flat in the middle of the development which has an outsidewindow area of 6m2 within a total external wall and window area of 28m2 with a U value of1.2 watts/m2 Co and compare to a flat on the top floor at one end where the window area isdoubled and the external wall area is three times as big. The U value of the walls is0.23watts/m2 Co

An electric hot plate is placed in a room which is maintained at a temperature of 297 K. The plate is maintained at a temperature of 403 K and has an emissivity of 0.8. If the plate surface resembles a circular disc of diameter 250 mm, electrical power consumed by the hot plate will be?

Derive the expression of q on a flat furnace wall in the x-direction

The heat conducts through the shape below. The temperature of the right face is 93 °C, while the left faceis at 23 °C. If the top and bottom faces are completely insulated, and the thermal conductivity of thematerial decreases with decreasing temperature, sketch the temperature profile inside the plate.

Calculate the heat transferred from the cube-shaped iron mass (a = 30 cm) to the environment at 20 ° C with all surfaces at a temperature of 100 ° C. (Assume that the heat is only from the surfaces, the inner parts of the surfaces are insulated.)

Consider a long horizontal pipe with a diameter of 90 mm and emissivity of 0.8 transfers steam at 227°C. Outside of the pipe is air at 27°C and the surroundings of the pipe are also at 27°C. You may assume the temperature of the pipe wall is the same as the temperature of the steam.   1. Find the heat loss per unit length (W/m) for the pipe when the air outside is still.   2. Find the heat loss per unit length (W/m) for the pipe when the wind outside is 8 m/s and blows perpendicularly across the pipe.

For the composite wall given in the sketcha) Determine the rate of heat transfer through the wallb) Determine the inner and outer surface temperatures of thewall.

An engineer proposes to decrease the gap between the windows of double pane window to decrease heat transfer. Is it good approach or not?         No, because by this way, radiation heat transfer will increase       No, because by this way, current loops will be created inside the gap       Yes, because by this way, less air will be trapped and therefore better insulation       Not sufficient information       Yes, because by this way, radiation heat transfer will decrease