Heat Transfer

Dr. Juma Yousuf Alaydi

Mechanical Engineering

IUG

THE PLANEWALL

Answer

Problem 2-17

THE OVERALL HEAT-TRANSFER COEFFICIENT

CRITICAL THICKNESS OF INSULATION

HEAT-SOURCE SYSTEMS

PlaneWall with Heat Sources

CYLINDER WITH HEAT SOURCES

CONDUCTION-CONVECTION SYSTEMS

When we combine the quantities, the energy balance yields

CASE 1 The fin is very long, and the temperature at the end of the fin is essentially that of the surrounding fluid

CASE 2 The fin is of finite length and loses heat by convection from its end

CASE 3 The end of the fin is insulated so that dT/dx=0 at x=L.

If we let:

For case 1the boundary conditions are

θ = θ0 at x = 0

θ =0 at x = ∞

For case 3 the boundary conditions are

The solution for case 2 is more involved algebraically, and

the result is

Discussion 3

Proper Length of a Fin

End of Chapter 2