1. Next, consider a "counter" flow heat exchanger by changing one of the direction of the flows. Find the minimum number of plates (including top and bottom plates) that will result

in an amount of exchanged heat equal to or greater than that of co-current (parallel) flow heat exchanger in Question 1, without changing the heat exchanger volume. Here, the effectiveness of a counter flow heat exchanger can be calculated using Eq. (3) as: E= 1-exp[-(1-R) NTU 1-Rexp[-(1-R) NTU] (3)