This assessment is a typical design problem for a shell and tube heat exchanger.

The heat exchanger consists of 160 double pass tubes of 1 cm in diameter. The manual for the heat exchanger states an area density of 250 m²/m³. Your problem involves heating up water using exhaust heat waste from a neighbouring electric generator.

If the cold water enters at a flow rate of 5 kg/s, the hot exhaust enters at around 300 C with a flowrate of 0.2 kg/s (Properties of air at 1 atm can be used here). Use an overall heat transfer coefficient of 240 W/m².K

1-  Plot as a function of mass flow rate (use a range between 0-20 kg/s)

• Hot outlet temperature
• Cold outlet temperature
• Effectiveness

2-  If the inlet temperature of the hot fluid has been reduced to 250 C, what is:

• The effectiveness of the heat exchanger
• The amount of water mass flow rate required to reach an outlet temperature of 40 C?
• Plot the hot water outlet temperature as a function of hot gas inlet temperature.