Heat and mass transfer

Question

Question 1: Define the given term:

a) Laminar flow.
b) Turbulent flow.

Question 2: Write brief notes on Newtonian fluids and Non Newtonian fluids.

Question 3: Write brief notes on boundary layer concept.

Question 4: What are the different types of boundary layers? Write brief notes on any two.

Question 5: Define the term Nusselt number.

Question 6: Define the term Prandtl number.

Question 7: Define the term Reynolds number.

Question 8: A flat plate 1.2 m wide, 0.35 m height and at 115o C is exposed to the ambient still air at 25^o C.

Compute the given:

a) Maximum velocity at 180 mm from the leading edge of the plate.
b) The boundary layer thickness at 180 m from the leading edge of the plate.
c) Local heat transfer coefficient 180 mm from the leading edge of the plate.
d) Average heat transfer coefficient over the surface of the plate.
e) Total mass flow via the boundary.
f) Heat loss from the plate.

Question 9: A large vertical plate of 4m height is maintained at 606^o C and exposed to atmospheric air at 106^oC.

Compute the heat transfer if the plate is 10 m wide.

Question 10: A thin 100 cm long and 10 cm wide horizontal plate is maintained at a uniform temperature of 150^oC in a large tank full of water at 75^o C. Estimate the rate of heat to be supplied to the plate to maintain constant plate temperature as the heat is dissipated from either side of the plate.

Question 11: 205 kg/hr of air are cooled from 100^o C to 30^o C by flowing via a 3.5 cm inner diameter pipe coil bent into a helix of 0.6 m diameter. Compute the value of air side heat transfer coefficient, if the properties of air at 65^o C are k = 0.0298 W/mK. µ = 0.003 kg/hr-m; Pr = 0.7; ρ = 1.044 kg/m³.

Question 12: Engine oil flows via a 50 mm diameter tube at an average temperature of 147^o C. The flow velocity is 80 cm/s. Compute the average heat transfer coefficient if the tube wall is maintained at a temperature of 200^o C and it is 2 m long.