# Heat Transfer

You have two layer of material to provide insulation. They have heat transfer co-efficient (k1>k2).
How will you obtain better insulation?

#### pandurangan Profile Answers by pandurangan

• Jun 17th, 2009

The material which has lower thermal condutivity should be insulated first or the insulation should increase order of k to get effective insulation.

#### gyanprakash maurya Profile Answers by gyanprakash maurya

• Jul 13th, 2009

By applying higher insulation layer at lower surface & lower at upper surface,

Q/A=K1*(dT/dX)
Q/A=K2*(dT/dX)
K1(DT)1+K2DT2=Q/A*X
FOR(q/A) MAX.
d(Q/A)/dX=0

#### gyanprakash maurya Profile Answers by gyanprakash maurya

• Jun 21st, 2010

q/a is directly proportional to k

to make less q/a less value of k requird

therefore K2 comes first

#### Affwan Hassan Profile Answers by Affwan Hassan Questions by Affwan Hassan

• Jul 8th, 2011

I do have a question here, If the material of lower insulation be bounded to the first system, doesn't that result in heat loss?

#### E Smardy

• Mar 22nd, 2013

I dont think you can generalise this problem - at least not for flat plane and cylindrical co-ordinates. It really depends on how much bigger k2 is relative to k1 and how big the pipe thickness is relative to the diameter.