Heat exchanger consisting of Coaxial Cables

[Delphi51]

The solution to dy/dx = ky is y = Ae^kx
so your solution should by T2 - T1 = Ae^kx, k = (constant expression with k4a's on top)
Let x = 0 to see what A should be.

Missing the closing bracket on the constants (after the C1). Instead of (T2 - T1)dx, you should have just x. Missing the constant before e.

Compare with the given answer in your first post. Looks like the answer has T1 - T2 instead of T2 - T1; probably doesn't matter.

 

[TFM]

okay, so differnce is that they should be other way around...

$$(T_1 - T_2) = Ae^{(\frac{\kappa 4a}{s m_1 C_1} - \frac{\kappa 4a}{sm_2C_2}) (T_2 - T_1))dx}$$

Now this is looking similar to the required equation, except T1 - T2 is on the other side, where A is, and instead on the left is delta T. Also, there exponential is:

$$(4a/s)\kappa [(m_1C_1) -1 – (m_2C_2) - 1]x$$