In a laundry, a heat exchanger is used to effect heat recovery from the waste water leaving the washing machines. The waste water is discharged at a temperature of 90°C and at a flow rate of 10,000 kg/h and is used to raise the temperature of fresh water from 10 to 50°C. The flow rate of fresh water is 12,000 kg/h. What is the duty of the heat exchanger and the outlet temperature of the waste water stream? Assume the properties of the waste and fresh water are the same as pure water. NB the specific heat of a general fluid vary by a significant amount between th inlet and outlet temperatures. Use value at average temperature of fluid.