D) You have been hired to design a heating system for a swimming pool that is 2 m deep, 25 m long, and 25 m wide. Your client desires that the heating system must satisfy two criteria. A) It must supply sufficient heat to raise the water temperature from 20 to 30C in 2 hours. The rate of heat loss from the water to the air at the outdoor design conditions is determined to be 960 W/m. B) The heater must also be able to maintain the pool at 30C at those conditions. Heat losses to the ground are expected to be small and can be disregarded. The efficiency of the heater is 80 percent. What heater size (in kW input) would you recommend to your client? A building with an internal volume of 400 m is to be heated by a 35-kW electric resistance heater placed in the duct inside the building. Initially, the air in the building is at 14C, and the local atmospheric pressure is 95 kPa. The building is losing heat to the surroundings at a steady rate of 450 kJ/min. Air is forced to flow through the duct and the heater steadily by a 250-W fan, and it experiences a temperature rise of 5C each time it passes through the duct, which may be assumed to be adiabatic. A. How long will it take for the air inside the building to reach an average temperature of 24C? B. Determine the average mass flow rate of air through the duct.