Week 5-8

Question 1

Summary results for heat transfer in a plane wall

Answer 1

Temperature distribution: T(x) = (T2-T1) (x/2) + T1
- independent of thermal conductivity
- linear in x
Heat transfer rate : qx = kA/L (T1-T2)
- dependant o thermal conductivity
- constant through the wall
Heat flux : qx’’ = k/L (T1-T2)
- dependant o thermal conductivity
- constant through the wall

Question 2

For general heat transfer between two fluids separated by a surface of non negligible thickness

Answer 2

q= U A 🔼 T
Where U is the overall heat transfer accounting for two convection and one conduction process

Question 3

What’s the equation for temp distribution in a wall

Answer 3

T(x) = (T2-T1)(x/L) + T1
With no heat generation and constant thermal conductivity

Question 4

What is the overall heat transfer coefficient

Answer 4

q = UAΔT
For two fluids separated by a surface of non negligible thickness

Question 5

Equation for thermal resistance, R (t,cond) and R (t,conv).

Answer 5

R (t,cond) = L/ kA
R( t,conv) = 1/ hA