Heat Transfer

For a counter current heat exchanger with Tih =` 80^circC`, `T^circ`c=` 60^circC`, `T^circ`h =` 50^circC` andTic = `30^circC`, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy

A. `(d^2T)/(dZ^2) > 0`
B. `(d^2T)/(dZ^2) = 0`
C. `(d^2T)/(dZ^2) < 0`
D. `(dT)/(dZ) = 0`

Answer : Option B

Explanation :