Isentropic expansion method

The isentropic expansion method assumes that the gas expands isentropically from its initial to final state. The following equation represents this case ... 

Wiedermatm (1986b) presents an alternative method for calculating work done by a fluid. The method uses the lambda model to describe isentropic expansion, and permits work to be expressed as a function of initial conditions and only one fluid parameter, lambda. Unfortunately, this parameter is known for very few fluids. 

Four methods are used to estimate the energy of explosion for a pressurized gas Brode s equation, isentropic expansion, isothermal expansion, and thermodynamic availability. Brode s method21 is perhaps the simplest approach. It determines the energy required to raise the pressure of the gas at constant volume from atmospheric pressure to the final gas pressure in the vessel. The resulting expression is... 

Next, we examine another method to calculate the isentropic expansion of the ideal gas. Recall that the entropy of an ideal gas is... 

Although the cylinder test appears to be a simple method, the treatment of the data provides a lot of important information regarding the tested explosive. It gives us the Gurney energy (from cylinder wall velocity) and the equation of the detonation products isentropic expansion. 

It is not uncommon to combine the isentropic and isenthalpic expansions to allow the formation of liquid in the refrigerator. This is done because of the technical difficulties associated with forming liquid in the engine. The Claude cycle is an example of a combination of these methods and is shown in Fig. 5a along with the corresponding temperature-entropy diagram (Fig. 5b). 

The expansion isentrope for hexogen/trinitrotoluene composition (50/50) obtained by the above method is shown in Figure 4.58. 

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