GATE Prev Year : Heat-Transfer Test-7

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Question 1

NTU method is used to calculate:

• ARate of heat transfer
• BRate of liquid flow
• CRate of conduction heat
• DRate of radiation

Question 2

Consider a two-dimensional laminar flow over a long cylinder as shown in the figure below.



The free stream velocity is and the free stream temperature is lower than the cylinder surface temperature . The local heat transfer coefficient is minimum at point

• A1
• B2
• C3
• D4

Question 3

Air enters a counter-flow heat exchanger at 70 °C and leaves at 40 °C. Water enters at 30 °C and eaves at 50 °C. The LMTD in deg. C is

• A5.65
• B14.43
• C19.52
• D20.17

Question 4

Which among the following statements are correct?

• AThe method of obtaining equations for predicting mass-transfer coefficients is use of dimensionless analysis.
• BDimensional analysis predicts various dimensionless parameters which are helpful in correlating experimental data.
• CMass transfer process, involves the transfer of mass into a steam flowing under forced convection
• DAll of these

Question 5

Heat flows through a composite slab, as shown below. The depth of the slab is 1 m. the k values are in W/m K. the overall thermal resistance in K/W is

• A17.2
• B21.9
• C28.6
• D39.2

Question 6

A solid cylinder (surface 2) is located at the center of a hollow sphere (surface 1). The diameter of the sphere is 1m, while the cylinder has a diameter and length of 0.5m each. The radiation configuration factor F11 is

• A0.375
• B0.625
• C0.75
• D1

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