Question 11. Air enters a rectangular duct measuring 30 cm by 40 cm with a velocity of 8.5 m/s and a temperature of 40 degree Celsius. The flowing air has a thermal conductivity 0.028 W/m K, kinematic viscosity 16.95 * 10¯⁶ m²/s and from empirical correlations the Nusselt number has been approximated to be 425. Find out the flow Reynolds number

Question 12. For turbulent flow, Reynolds number must be

Question 13. For laminar flow, Reynolds number should be

Question 14. What is the value of convective coefficient of air and superheated steam in case of forced convection?

Question 15. Heat is being transferred by convection from water at 48 degree Celsius to glass plate whose surface is exposed to water at 40 degree Celsius. The thermal conductivity of water is 0.6 W/m K and the thermal conductivity of glass is 1.2 W/m K. The spectral gradient of temperature in the water at the water glass interface is 10¯⁴ K/m. The heat transfer coefficient in W/m² K is

Question 16. The fluid particles move in flat or curved un-mixing layers or streams and follow a smooth continuous path. This type of flow is known as

Question 17. The characteristic dimension d in the relation R E = V d p/δ is the equivalent diameter and is defined as how many times the cross-sectional flow area divided by wetted perimeter

Question 18. For a duct of rectangular cross-section with length l and breadth b, the value of d e is

Question 19. If an annulus has an inner diameter of d₁ and an outer diameter of d₂ then the equivalent diameter is

Question 20. In many flow situations, the duct can be
(i) Circular
(ii) Rectangle
(iii) Trapezoidal
(iv) Annulus
Identify the correct option