An ideal gas, Cp = (7/2)R, is heated in a steady-flow heat exchanger from 70°C to 190°C by another stream of the same ideal gas which enters at320°C. The flow rates of the two streams are the same, and heat losses fromthe exchanger are negligible. Calculate the molar entropy changes of the two gas streams for both parallel andcountercurrent flow in the exchanger. What is ΔStotal in each case?
Temperature drop of stream ‘B’ in either case of flow is the same as the temperature rise of first stream ‘A’ = 120oC. Thus, exit temperture of stream ‘B’ = 200oC
(in both types of flow) = 
