Air is heated in a duct as it flows over resistance wires. consider a 20 kw electric heating system. air enters the heating section at 100 kpa and 15°c with a volumetric flow rate of 140 m/min. if heat is lost from air in the duct to the surroundings at a rate of 150 w, determine (a) the exit temperature (72) of air and (b) the energetic efficiency (ou). use the pg model for air and neglect the power consumed by the fan. (c) draw an energy flow diagram for the system.

A2-m rigid tank initially contains saturated water vapor at 100 kpa. the tank is connected to a supply line through a valve. steam is flowing in the supply line at 600 kpa and 300 c. the valve is opened, and steam is allowed to enter the tank until the pressure in the tank reaches the line pressure, at which point the valve is closed. a thermometer placed in the tank indicates that the temperature at the final state is 200°c. determine (a) the mass of steam that has entered the tank (b) the amount of heat transfer.