Using thermodynamic availability to determine the energy of explosion

Current methods to determine the thermodynamic energy of explosion are based on the Helmholtz free energy. The Helmholtz free energy represents the maximum work available from a system during a constant temperature process. For many real explosions, the material is initially at a temperature or pressure higher than the ambient environment. Thus, the Helmholtz free energy does not account for all of the energy sources. The thermodynamic availability provides a general approach to determine the maximum work available from any process. Furthermore, the availability provides a much more formal and structured method for performing the calculations. This paper provides the formal basis, demonstrates the application of availabilty using a number of examples, and provides a table of availability data.