Download Aptitude Crack
img not found img not found

Heat Transfer - Engineering

Q1:

A sphere of radius 'R1' is enclosed in a sphere of radius 'R2'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is

A 0

B R2/(R1+R2)

C 1

D (R1/R2)2

ANS:B - R2/(R1+R2)

The view factor (or shape factor) for radiative heat transfer from the outer sphere to the inner sphere is given by: 22F2→1​=A2​A1​​=4πR22​A1​​ Where:

  • A1​ is the surface area of the inner sphere.
  • A2​ is the surface area of the outer sphere.
For two concentric spheres, the surface area of the inner sphere (A1​) is equal to the surface area of the outer sphere (A2​), which is: 22A1​=A2​=4πR22​ Therefore, the view factor from the outer sphere to the inner sphere is: F2→1​=A2​A1​​=4πR22​4πR22​​=1 So, the correct answer is: F2→1​=1