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    Assignment - 2

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    Buckshu Phd
    HMT

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    Assignment - 2

    Uploaded by

    Buckshu Phd
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    HMT

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    Assignment -2

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    HMT

    Copyright:

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    4 views1 page

    Assignment - 2

    Uploaded by

    Buckshu Phd
    HMT

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 1

    ME3691 HEAT AND MASS TRANSFER

    Assignment – II Last date to submit 26.02.24

    1. Air at 20oC, 1m/sec flows over a flat plate of 2m x1m maintained at


    400C.Determine (i) boundary layer thickness at 40 cm from leading edge (ii)
    boundary layer thickness at 2 m from leading edge (iii) localized heat transfer co-
    efficient at 2 m (iv) average heat transfer co-efficient from leading to 2 m length.
    2. Air at 20°C and at a pressure of 1 bar is flowing over a flat plate at a velocity of
    3m/s. If the plate is 280 mm wide and at 56°C calculate the following at x = 280
    mm: (i) Boundary layer thickness, (ii) Local friction coefficient, (iii) Average
    friction coefficient, (iv) Thickness of the thermal boundary layer thickness, (v)
    Local convective heat transfer coefficient, (vi) Average convective heat transfer
    coefficient, (vii) Rate of heat transfer by convection, (viii) Total drag force on the
    plate, (ix) Total mass flow rate through the boundary.
    3. Engine oil flows through a 50mm diameter tube at an average temperature of
    1470C. The flow velocity is 80 cm/s. Calculate the average heat transfer
    coefficient if the tube wall is maintained at a temperature of 2000C and it is 2 m
    long.
    4. A heated sphere having a diameter of 30mm is maintained at a temperature of
    900C and is placed in water stream at 200C. The water flow velocity is 3.5 m/s.
    Calculate the heat loss from the sphere.
    5. A vertical pipe 80 mm diameter and 2 m height is maintained at a constant
    temperature of 120oC. The pipe is surrounded by still atmospheric air at 30oC.
    Find heat loss by natural convection.
    6. A long 10cm diameter steam pipe whose external surface temperature is 110°C
    passes through some open area that is not protected against the winds. Determine
    the rate of heat loss from the pipe per unit length when the air is at 1atm and
    10°C and the wind blowing across the pipe at a velocity of 8 m/s.
    7. Consider a 0.6 m x 0.6 m thin square plate in a room at 30°C. One side of the
    plate is maintained at a temperature of 90°C, while the other side is insulated.
    Determine the rate of heat transfer from the plate by natural convection if the
    plate is horizontal with hot surface (a) facing up, and (b) facing down.
    8. Determine average heat transfer co-efficient over entire length from vertical plate
    of height 2m to surrounding air, if it is known that the surface temperature of the
    plate is 105°C. Assume the ambient temperature is 15°C.

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