Water is to be heated from its pipeline temperature of 20°C to 90°C using superheated steam at 450^◦C and 2.5 MPa in a steady-state process to produce 10 kg/s of heated water. In each of the processes below, assume there is no heat loss.

a. The heating is to be done in a mixing tank by direct injection of the steam, all of which condenses. Determine the two inlet mass flows needed to meet the desired hot water flow rate. 

b. Instead of direct mixing, a heat exchanger will be used in which the water to be heated will flow inside copper tubes and the steam will partially condense on the outside of the tubes. In this case heat will flow from the steam to the water, but the two streams are not mixed. Calculate the steam flow rate if the steam leaves the heat exchanger at 50 percent quality at 100°C.