5.49 In a distillery, a PFHX with a 1-1/U counterflow plate arrangement is being used to cool down a flow of pure ethanol using cold water. The plates are stamped with a 30° chevron pattern. The plate width is 248 mm and the active heat transfer area of each plate is 0.2 m2. The plates are separated by a space of 1.5 mm. The ethanol enters the heat exchanger at a flow rate of 2.9 kg/s at an average temperature of 80°C. The cold water flows at a rate of 3.8 kg/s with an average temperature of 15°C. The diameter of the hot and cold ports on the heat exchanger is 125 mm. The heat exchanger has 54 plates. Determine the total pressure drop of each fluid as it passes through this heat exchanger (kPa).

5.50 Distilled water is being used to cool a 20% ethylene glycol solution. The ethylene glycol solution flows at 4.4 L/s to a 1/1-U counterflow PFHX. The ethylene glycol solution enters the heat exchanger at 32°C where it transfers heat to the distilled water. The water enters the heat exchanger at 4.1 L/s with a temperature of 15°C. The plates are made from titanium and have a 30° chevron pattern.

The plates have a height of 1.5 m and a width of 0.5 m. Each plate has a thickness of 0.8 mm and the plates are spaced 4 mm apart. There are 18 active plates in the heat exchanger. The fouling factor for the ethylene glycol solution can be taken as 5 × 10−7 m2 K/W. Determine the following:

a. Outlet temperatures of both fluids (°C)

b. Pressure drop of each fluid because of plate friction as it passes through the heat exchanger (kPa).