Cold water (Cp = 4.18 kJ/kg.°C) leading to a shower enters a well-insulated, thin-walled, double-pipe, counter- flow heat exchanger at 15°C at a rate of 0.25 kg/s and is heated to 45°C by hot water (cp = 4.19 kJ/kg.ºC) that enters at 100°C at a rate of 3 kg/s. Determine (a) the rate of heat transfer and (b) the rate of exergy destruction in the heat exchanger. Take To = 25°C. Additional requirement for above problem: Calculate the second law efficiency of the process.