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Heat-transfer Questions Set 16:

Quiz Mode

If the temperature difference is 600 degrees Celsius and the thermal resistance is 0.2857, find the heat flow rate.

599.71 W

600.2857 W

171.42 W

2100 W

Solution:

When heat is transferred by the movement of matter, what mode of heat transfer is it called?

Lattice vibration

Transport of free electron

Radiation

Convection

Solution:

When the fin thickness is sufficiently small, the heat flow through the fin can be approximated by-

1D heat conduction

2D heat conduction

3D heat conduction

Inconclusive

Solution:

Heat transfer by conduction, convection and radiation can be observed in all of these processes:

melting of ice

boiler furnaces

condensation of steam in condenser

all of these

Solution:

If the thickness of the plate is 0.4 m, the thermal conductivity is 0.7 W/m·K, and the area is 2 m², then find the thermal resistance.

0.465 K/W

0.2857 K/W

0.7899 K/W

0.1115 K/W

Solution:

For free convection boiling with laminar flow of fluid, the heat transfer rate is directly proportional to:

(Tsur - Tsat)^(5/4)

(Tsur - Tsat)^(5/3)

(Tsur - Tsat)^(5/2)

(Tsur - Tsat)^(5/7)

Solution:

In a steam power plant, a steam condenser is at a temperature of 60°C. The steam enters the condenser at 30°C and leaves at 45°C. The logarithmic mean temperature difference (LMTD) of the condenser is:

20°C

21.6°C

25°C

30.13°C

Solution:

A pipe is carrying hot water at a temperature of 80°C, and the temperature of the air outside the pipe is 25°C. The convection heat transfer coefficient (h) is 3.586 W/m²K. The surface area of the pipe is 0.628 m². The rate of heat transfer is:

342.76 W

123.86 W

96.23 W

246.76 W

Solution:

The heat generated in a wire is 15.89 × 10⁸ W/m³, with a surface temperature of 93 degrees Celsius, a radius of 0.0016 m, and a thermal conductivity of 22.5 W/(m·K). Determine the center temperature of the wire.

100 degrees Celsius.

145.62 degrees Celsius.

138.2 degrees Celsius.

77.54 degrees Celsius.

Solution:

Which of the following is true about the log mean temperature difference (LMTD) in a heat exchanger, when the inlet and outlet temperatures of the cold and hot fluids are the same?

Both have the same value of LMTD

LMTD is higher for a counter-flow heat exchanger than a parallel flow heat exchanger

LMTD is higher for a parallel flow heat exchanger than a counter-flow heat exchanger

We can't say

Heat-transfer Questions Set 16:

If the temperature difference is 600 degrees Celsius and the thermal resistance is 0.2857, find the heat flow rate.

Solution:

When heat is transferred by the movement of matter, what mode of heat transfer is it called?

Solution:

When the fin thickness is sufficiently small, the heat flow through the fin can be approximated by-

Solution:

Heat transfer by conduction, convection and radiation can be observed in all of these processes:

Solution:

If the thickness of the plate is 0.4 m, the thermal conductivity is 0.7 W/m·K, and the area is 2 m², then find the thermal resistance.

Solution:

For free convection boiling with laminar flow of fluid, the heat transfer rate is directly proportional to:

Solution:

In a steam power plant, a steam condenser is at a temperature of 60°C. The steam enters the condenser at 30°C and leaves at 45°C. The logarithmic mean temperature difference (LMTD) of the condenser is:

Solution:

A pipe is carrying hot water at a temperature of 80°C, and the temperature of the air outside the pipe is 25°C. The convection heat transfer coefficient (h) is 3.586 W/m²K. The surface area of the pipe is 0.628 m². The rate of heat transfer is:

Solution:

The heat generated in a wire is 15.89 × 10⁸ W/m³, with a surface temperature of 93 degrees Celsius, a radius of 0.0016 m, and a thermal conductivity of 22.5 W/(m·K). Determine the center temperature of the wire.

Solution:

Which of the following is true about the log mean temperature difference (LMTD) in a heat exchanger, when the inlet and outlet temperatures of the cold and hot fluids are the same?

Solution:

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