GATE ME topic:heat-transfer PYQs & Answers — Page 2

Questions 11–20 of 62. Imported answers require independent review unless marked reviewed.

Consider a hydrodynamically fully developed laminar flow through a circular pipe with the flow along the axis (i.e., z direction). In the following statements,

is the temperature of the fluid,

is the wall temperature and

is the bulk mean temperature of the fluid. Which one of the following statements is TRUE?

Your answerChoose one option.

For a thermally fully developed flow,

, always.

For constant wall temperature of the duct,

Nusselt number varies linearly along the

direction for a thermally fully developed flow.

For constant wall temperature (

) of the duct,

increases exponentially with distance along

direction.

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Consider a slab of 20 mm thickness. There is a uniform heat generation of

MW/m

inside the slab. The left and right faces of the slab are maintained at 150 °C and 110 °C, respectively. The plate has a constant thermal conductivity of 200 W/(m.K). Considering a 1-D steady state heat conduction, the location of the maximum temperature from the left face will be at _____ mm (answer in integer).

Diagram for Mechanical Engineering question 48

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A condenser is used as a heat exchanger in a large steam power plant in which steam is condensed to liquid water. The condenser is a shell and tube heat exchanger which consists of 1 shell and 20,000 tubes. Water flows through each of the tubes at a rate of 1 kg/s with an inlet temperature of 30 °C. The steam in the condenser shell condenses at the rate of 430 kg/s at a temperature of 50 °C. If the heat of vaporization is 2.326 MJ/kg and specific heat of water is 4 kJ/(kg.K), the effectiveness of the heat exchanger is ______ (rounded off to 3 decimal places).

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Consider a hemispherical furnace of diameter

m with a flat base. The dome of the furnace has an emissivity of 0.7 and the flat base is a blackbody. The base and the dome are maintained at uniform temperatures of 300 K and 1200 K, respectively. Under steady state conditions, the rate of radiation heat transfer from the dome to the base is ______ kW (rounded off to the nearest integer).

Use Stefan-Boltzmann constant =

W/(m² K⁴)

Diagram for Mechanical Engineering question 50

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Consider incompressible laminar flow of a constant property Newtonian fluid in an isothermal circular tube. The flow is steady with fully-developed temperature and velocity profiles. The Nusselt number for this flow depends on

Your answerChoose one option.

neither the Reynolds number nor the Prandtl number

both the Reynolds and Prandtl numbers

the Reynolds number but not the Prandtl number

the Prandtl number but not the Reynolds number

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Consider a laterally insulated rod of length L and constant thermal conductivity. Assuming one-dimensional heat conduction in the rod, which of the following steady-state temperature profile(s) can occur without internal heat generation?

Your answerSelect all correct options. You can choose more than one.

Diagram for Mechanical Engineering question 28

Diagram for Mechanical Engineering question 28 (figure 2)

Diagram for Mechanical Engineering question 28 (figure 3)

Diagram for Mechanical Engineering question 28 (figure 4)

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Consider a counter-flow heat exchanger with the inlet temperatures of two fluids (1 and 2) being

K and

K. The heat capacity rates of the two fluids are

W/K and

W/K, and the effectiveness of the heat exchanger is 0.5. The actual heat transfer rate is _____ kW.

(Answer in integer)

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A cylindrical rod of length

and diameter

is placed inside a cubic enclosure of side length

denotes the inner surface of the cube. The view-factor

Your answerChoose one option.

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A very large metal plate of thickness

and thermal conductivity

is cooled by a stream of air at temperature

with a heat transfer coefficient

, as shown in the figure. The centerline temperature of the plate is

Diagram for Mechanical Engineering question 47

In which of the following case(s) can the lumped parameter model be used to study the heat transfer in the metal plate?

Your answerSelect all correct options. You can choose more than one.

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Which of the following non-dimensional terms is an estimate of Nusselt number?

Your answerChoose one option.

Ratio of internal thermal resistance of a solid to the boundary layer thermal resistance

Ratio of the rate at which internal energy is added to the rate of conduction heat transfer

Non-dimensional temperature gradient

Non-dimensional velocity gradient multiplied by Prandtl number

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GATE ME topic:heat-transfer PYQs

Question 19

Question 48

Question 49

Question 50

Question 21

Question 28

Question 35

Question 43

Question 47

Question 25