Solve Problem 11.2 for a two pass/two pass arrangement.
Problem 11.2
A gasketed-plate heat exchanger will be used for heating city water (Rfc = 0.00006 m2 · K/W) using the waste water available at 90°C. The vertical distance between the ports of the plate is 1.60 m and the width of the plate is 0.50 m with a gap between the plates of 6 mm. The enlargement factor is given by the manufacturer as 1.17 and the chevron angle is 50°. The plates are made of titanium (k = 20 W/m · K) with a thickness of 0.0006 m. The port diameter is 0.15 m. The cold water enters the plate heat exchanger at 15°C and leaves at 45°C at a rate of 6 kg/s and it will be heated by the hot water available at 90°C, flowing at a rate of 12 kg/s. Considering single-pass arrangements for both streams, calculate:
a. The effective surface area and the number of plates of this heat exchanger
b. The pressure drop for both streams.