thermodynamics An exhaust pipe of 75 mm outside diameter is cool by surrounding it by an annular space containing water.

[answerhappygod]

thermodynamics
An exhaust pipe of 75 mm outside diameter is cool by surrounding
it by an annular space containing water. The exhaust gas enters the
exhaust pipe at 350 C and the water enters from the mains at 10°C.
The heat transfer coefficients for the gases and water are 0.3 and
1.5 kW/m2 K, respectively and the pipe thickness may be taken to be
negligible. The gases are cool to 100 °C and the mean specific heat
capacity at constant pressure is 1.13 kJ/ kg K. The gas flow rate
is 200kg/hr and the water flow rate is 1400 kg/h. The specific heat
capacity of water is 4.19 kJ/kg K.
Calculate:
State three (3) assumptions.
(i) The required pipe length for parallel-flow;
(ii) The required pipe length for counter-flow.