1) As part of a fish processing system a counter flow shell and tube heat exchanger is uses seawater to cool freshwater. Freshwater flow enters at a rate of 2.2 kg/s and flows inside 50 tubes of internal diameter 20 mm and wall thickness 2.5 mm. The seawater flows at a rate of 3 kg/s in shell. The pipes are made from steel with a thermal conductivity of 50 W/mK. The inlet temperature of the seawater and freshwater are 4°C and 30°C respectively. The outlet temperature for the seawater is 9°C. The length of each tube is 4.53m. The tube-side heat transfer coefficient can be estimated from the following relationship:
Nu = 0.023 Re 0.8 Pr 0.33
Transport properties for the fluids:
Seawater Freshwater
Specific Heat Capacity (J/ kg K) c p = 3700 c p = 4180
Dynamic Viscosity (kg/ms) µ =1.73 x 10 -3 µ = 0.83 x 10 -3
Thermal Conductivity (W/mK) k = 0.51 k = 0.614
Prandtl Number 12.55 5.65
Estimate the heat transfer coefficient for the seawater side of the heat exchanger.
