In a tube in tube type parallel flow heat exchanger, the hot water at 80°C is cooled to 65°C by cold water entering the heat exchanger at 20°C and leaving at 35°C. What would be the exit temperatures...

In a tube in tube type parallel flow heat exchanger, the hot water at 80°C is cooled to 65°C by cold water entering the heat exchanger at 20°C and leaving at 35°C. What would be the exit temperatures if the flow rates of water are doubled ?

Discuss laminar sublayer, buffer layer and turbulent layer in a boundary layer.