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·°C) that enters at 100°C at a rate of 3 kg/s. Determine
(a) the rate of heat transfer and
(b) the rate of entropy generation in the heat exchanger.