1. Derive the Tlm equation for a cocurrent (a.k.a. parallel flow) heat exchanger and comment on how your result compares to that for a countercurrent (a.k.a. counterflow) heat exchanger?

2.Oil (p = 2.1 kJ/kgK) is used to heat water in a tube-and-shell heat exchanger with a single shell pass and two tube passes. The overall heat transfer coefficient is 525 W/m2 K. The mass flow rates are 7 kg/s for the oil and 10 kg/s for the water. The oil and water enter the heat exchanger at 240 C and 20 C, respectively. The heat exchanger is to be designed so that the water leaves the heat exchanger with a minimum temperature of 80 C. Calculate the heat transfer surface area required to achieve this temperature.*

3. You are using a shell-and-tube heat exchanger (single-pass on both sides) to cool a 100 kg/min process stream from 80 C to 50 C. This process is to be performed using 100 kg/min of chilled water supplied at 5 C, and the process fluid has water-like thermal properties. If the overall heat transfer coefficient for this process (U) is 700 W/m2 K, please determine the required heat transfer area if the heat exchanger is being operated:

(a) Countercurrently.

(b) Cocurrently