Catastrophic explosions of steam boilers in the 1800s and early 1900s resulted in hundreds of deaths, which prompted the development of the ASME Boiler and Pressure Vessel Code in 1915. Considering that the pressurized fluid in a vessel eventually reaches equilibrium with its surroundings shortly after the explosion, the work that a pressurized fluid would do if allowed to expand adiabatically to the state of the surroundings can be viewed as the explosive energy of the pressurized fluid. Because of the very short time period of the explosion and the apparent stability afterward, the explosion process can be considered to be adiabatic with no changes in kinetic and potential energies. The closed-system conservation of energy relation in this case reduces to Wout = m (u1 €“ u2). Then the explosive energy Eexp becomes Eexp = m (u1 €“ u2) where the subscripts 1 and 2 refer to the state of the fluid before and after the explosion, respectively. The specific explosion energy Eexp is usually expressed per unit volume, and it is obtained by dividing the quantity above by the total V of the vessel: Eexp = u1 €“ u2/v1 where v1 is the specific volume of the fluid before the explosion. Show that the specific explosion energy of an ideal gas with constant specific heat is also; determine the total explosion energy of 20 m3 of air at 5 MPa and 100°C when the surroundings are at 20°C.

Transcribed Image Text:

部- ) expー Steam boiler Pi