An adiabatic condenser (a heat exchanger in a steam power plant) accepts steam at 25 kPa and quality of 95%, and at a mass flow rate of 10 kg/s. The steam is entirely converted to saturated liquid at the same pressure. The steam is cooled in the condenser by using water from a nearby river with a temperature of 15 °C and volumetric flow rate of 30 m3/s. The mass flow rate of the river water through the condenser is maintained at the minimum possible value to condense the steam (hint: you may assume that river water leaving the condenser is isothermal with the saturated liquid, but not all of the river water is diverted to the condenser). Determine, a) the minimum mass flow rate of water that must be diverted from the river and through the condenser (kg/s), b) the temperature of the river downstream (Tdown) of the power plant assuming complete mixing of the return water and un-diverted river flow (°C).