A fuel cell stack is made from 40 cells of the type described and tested in the previous problem. The fuel cell stack operating point is at i=1000 mA/cm2 . The fuel cell needs 16W to operate and the fuel loss due to leakage is 2%. a. What are the current, potential and power of the fuel cell stack at this operating point? b. What is the overall electrical system efficiency based on fuel consumption?

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.