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F1003

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cooled from 370K to 340K. At the same time 14 kg/s of cooling water at 303K

enters the heat exchanger. The flow conditions are such that overall heat transfer

coefficient remains constant at 2270 W/m? K. Determine the effectiveness and

the heat transfer area required, assuming two streams are in parallel flow.

Assume the specific heat for the both the streams = 4.2 kJ/kg K.

PART C
Answer any four full questions, each carries 10 marks.
Define Irradiation and Radiosity for a grey body. (3)
State and Explain Wein’s displacement law (3)
Distinguish between a black body and gray body (4)
Derive the following relation for the radiant heat exchange between two gray (10)

surfaces

46 (1 − 12)

(Qi2)net = 1-௪)

6

1

1-2

+(

1-€2

62

۱

41
42

Calculate the heat exchange by radiation between the surfaces of two long (10)

cylinders having radii 120 mm and 60 mm respectively. The axes of the cylinders

are parallel to each other. The inner cylinder is maintained at a temperature of

130°C and emissivity of 0.6. Outer cylinder is maintained at a temperature of

30 C and emissivity of 0.5.

State and explain the governing law for Diffusion mass transfer?

Discuss the analogy between heat transfer and mass transfer

What are the different modes of mass transfer, give examples for each
Explain the phenomenon of equimolar counter diffusion with an example

Define and explain the physical significance of

i) Schmidt number

ii) Sherwood number

(4)
(6)
(6)
(4)
(4)

Dry air at 30°C and 1 atm flows over a wet flat plate 600 mm long at a velocity (6)

of 50 m/s. Calculate the mass transfer co-efficient of water vapour in air at the

end of the plate. Take the diffusion co-efficient of water vapour in air,

ற = 0.26 x 104 ‏وم‎

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