Grashoff number, which is defined as g . β (Ts – T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to ____________ force?

Related Mcqs:

1. When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is _______________?

   A. Free convection
   B. Entry length problem in laminar forced conduction (developing thermal boundary layer)
   C. Mixed convection (both free and forced)
   D. Forced convection

2. Grashoff number is given by________________?

   A. gD3.β.Δtρ2/μ2
   B. gD2βΔtρ/μ2
   C. gD2βΔtP2μ
   D. gD3βΔtP2/μ

3. Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the________________?

   A. Surrounding temperature
   B. Average temperature of the fin
   C. Temperature of the fin end
   D. Constant temperature equal to that of the base

4. Stefan-Boltzmann law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K) ?

   A. t4
   B. T4
   C. 1/t4
   D. 1/T4

5. Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is ________________ law?

   A. Stefan’s
   B. Dalton’s
   C. Wien’s
   D. Kirchoff’s

6. In the free convection regime of pool boiling, the heat flux is proportional to__________________?

   A. Δt1/2
   B. Δt2
   C. Δt5/4
   D. Δt

7. The heat flux in the nucleate boiling regimes is proportional to (where, ΔT = excess temperature) ?

   A. (ΔT)2
   B. (ΔT)4
   C. (ΔT)3
   D. √(ΔT)

8. For small temperature difference, the heat transfer rate as per Newton’s law of cooling is proportional to (where, Δt = excess temperature) ?

   A. Δt
   B. Δt2
   C. Δt3
   D. √(Δt)

9. The statement that “maximum wavelength of radiation is inversely proportional to the temperature” is ______________ law?

   A. Stefan-Boltzmann’s
   B. Planck’s
   C. Wien’s displacement
   D. None of these

10. A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to_____________________?

    A. d0.8
    B. d-0.2
    C. d-1
    D. d-1.8