Questions from Principles Of Heat Transfer

Q: A mild steel (1% carbon), 2-cm-

A mild steel (1% carbon), 2-cm-OD shaft rotating in 20°C air at 20,000 rev/min is attached to two bearings 0.7 m apart, as shown below. If the temperature at the bearings is 90°...

Q: Reconsider the problem of cooling of a rotating rod (shaft)

Reconsider the problem of cooling of a rotating rod (shaft) by natural convection described in Example 8.6. Determine the shaft rotation at which the heat transfer contribution due to the rotation con...

Q: A horizontal, 3-mm-thick flat-copper plate

A horizontal, 3-mm-thick flat-copper plate, 1-m long and 0.5-m wide, is exposed in air at 27°C to radiation from the sun. If the total rate of solar radiation absorbed is 300 W and the combined radiat...

Q: Consider a vertical, 20-cm-tall, flat plate

Consider a vertical, 20-cm-tall, flat plate at 120°C, suspended in a fluid at 100°C. If the fluid is being forced past the plate from above, estimate the fluid velocity for which natural convection be...

Q: Suppose a thin, vertical, flat plate 60 cm high and

Suppose a thin, vertical, flat plate 60 cm high and 40 cm wide is immersed in a fluid flowing parallel to its surface. If the plate is at 40°C and the fluid at 10°C, estimate the Reynolds number at wh...

Q: A vertical, isothermal plate 30 cm high is suspended in an

A vertical, isothermal plate 30 cm high is suspended in an atmospheric airstream flowing at 2 m/s in a vertical direction. If the air is at 16°C, estimate the plate temperature for which the natural-c...

Q: A horizontal disk 1 m in diameter rotates in air at 25

A horizontal disk 1 m in diameter rotates in air at 25°C. If the disk is at 100°C, estimate the number of revolutions per minute at which natural convection for a stationary disk becomes less than 10%...

Q: A gas-fired industrial furnace is used to generate steam.

A gas-fired industrial furnace is used to generate steam. The furnace is a 3-m cubic structure, and the interior surfaces are completely covered with boiler tubes transporting pressurized wet steam at...

Q: The following equation has been proposed for the heat transfer coefficient in

The following equation has been proposed for the heat transfer coefficient in natural convection from long vertical cylinders to air at atmospheric pressure: where Tf = the film temperature / is in th...

Q: A 0.15-m-square circuit board is to

A 0.15-m-square circuit board is to be cooled in a vertical position, as shown in the sketch. The board is insulated on one side, while on the other, 100 closely spaced square chips are mounted. Each...