Pick out the correct equation ?

Related Mcqs:

1. Choose the correct equation ?

   A. Nu = (Re) (Pr) (Gz)
   B. Nu = (Re) (Pr) (St)
   C. Nu = (Re) (Pr)
   D. Nu = (Pr) (St)

2. Pick out the correct statement ?

   A. 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F
   B. In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity
   C. In unsteady state heat conduction, heat flows in the direction of temperature rise
   D. In heat transfer by forced convection, Grashoff number is very important

3. Pick out the correct statement ?

   A. Higher is the temperature of the radiating body, higher is the wavelength of radiation
   B. Logarithmic mean area is used for calculating the heat flow rate through a thick walled
   cylinder
   C. The wavelength corresponding to maximum mono-chromatic emissive power increases with
   rise in temperature
   D. Solid angle subtended by the finite surface at the radiating element is called the angle of
   incidence

4. Dittus-Boelter equation used for the determination of heat transfer co-efficient is valid ___________________?

   A. For fluids in laminar flow
   B. For fluids in turbulent flow
   C. When Grashoff number is very important
   D. For liquid metals

5. The equation, Nst = f/2, is the _____________ analogy?

   A. Colburn
   B. Reynolds
   C. Prandtl
   D. None of these

6. The equation, Nst = (f/2)/[1 + 5 (Npr – 1) √(f/2)], corresponds to ______________ analogy?

   A. Von-Karman
   B. Reynolds
   C. Colburn
   D. Prandtl

7. Out of the following four assumptions used in the derivation of the equation for LMTD [LMTD = (Δt1 – Δt2)/ln(Δt1/Δt2)], which one is subject to the largest deviation in practice ?

   A. Constant overall heat transfer co-efficient.
   B. Constant rate of fluid flow
   C. Constant specific heat
   D. No partial phase change in the system

8. In the equation Q = UAΔt; Δt is_________________________?

   A. Geometric mean temperature difference
   B. Arithmetic mean temperature difference
   C. Logarithmic mean temperature difference
   D. The difference of average bulk temperatures of hot and cold fluids

9. Dittus-Boelter equation cannot be used for molten metals mainly due to its very low_____________________?

   A. Prandtl number
   B. Grashoff number
   C. Thermal conductivity
   D. Viscosity

10. Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ?

    A. Dittus-Boelter equation
    B. Sieder-Tate equation
    C. Nusselt equation
    D. None of these