1. A closed rigid tank (constant volume) initially contains 10 kg of saturated water vapor at 40 bar (state 1). The pressure of water drops to 20 bar (state 2) as a result of heat transfer from the water tank to ambient air. Please find the following parameters:

(a) The temperature at state 1;

(b) The volume of the tank at state 1, in m^3;

(c) The volume of the tank and specific volume of water at state 2;

(d) The phase of water at state 2;

(e) The specific internal energy u (kJ/kg) of water at state 2;

(f) The total internal energy of water at state 2;

2. In USA, 53% of total electric power is currently generated by coal-fired power plants. Typically, generation of 1 kWh of electricity by a coal-fired power plant produces 966 g of carbon dioxide (CO2). The world’s total wind energy capacity is 39,294 MW. Instead wind turbines generate negligible CO2. Determine the amount of CO2 emission per year that is saved by the use of the wind turbines for replacement of coal-fired power plants.