A 80-L hot-water tank has a working pressure of 0.5 MPa. Due to some malfunction the pressure in the tank rises to 2 MPa, at which point the tank explodes the process of which is considered isentropic. Calculate the total explosion energy of the tank in terms of TNT equivalence. The explosion energy of TNT is 3,250 kJ/kg. Assume that the atmospheric pressure is 100 kPa, and the liquid in the tank to be saturated at the time of explosion. (Ans: 1.971 kg)