Pressure-volume energy

Prompt instrumentation is usually intended to measure quantities while uniaxial strain conditions still prevail, i.e., before the arrival of any lateral edge effects. The quantities of interest are nearly always the shock velocity or stress wave velocity, the material (particle) velocity behind the shock or throughout the wave, and the pressure behind the shock or throughout the wave. Knowledge of any two of these quantities allows one to calculate the pressure-volume-energy path followed by the specimen material during the experimental event, i.e., it provides basic information about the material s equation of state (EOS). Time-resolved temperature measurements can further define the equation-of-state characteristics. 

Examine all process parameters. Parameters (e.g., pressure, temperature, flow rate, level, pH) that are controlled or measured in a process are good indicators of possible process hazards. Process parameters should be examined for all modes of operation, independent of process chemicals, because some hazards exist that do not involve the chemicals. For example, if a process uses high-pressure steam, then both thermal energy and pressure-volume energy hazards exist even though steam is non-toxic, non-flammable, and non-reactive with most materials. 

PRESSURE- VOLUME ENERGY Volume of compressible fluid held at elevated pressure Tank or enclosure rupture High-velocity leak or spray... 

PVE Pressure-Volume-Energy of an explosive s detonation products... 

The Jones-Wilkins-Lee equation of state has been used to describe accurately the pressure-volume-energy behavior of the detonation products of expls in applications of metal acceleration. The parameters for TNT are available in comparison with other common expls (Ref 141)... 

Pressure-Volume Energy Produces Mechanical Work (MW) (Lowering Pressure Through the Transition Zone Drives Contraction)... 

There will be an increase in volume due to stretching of the interface as dV = A8n. The increase in volume will also lead to decrease in pressure volume energy as... 

Thennal equilibrium means free transfer (exchange) of energy in the fonn of heat, mechanical (liydrostatic) equilibrium means free transfer of energy in the fonn of pressure-volume work, and material equilibrium means free transfer... 

If there is no volume change (dV= 0), then obviously there is no pressure-volume work done (du = 0) irrespective of the pressure, and it follows from equation (A2.1.10) that the change in energy is due entirely to the heat absorbed, which can be designated as qy. 

Note that in this special case, the heat absorbed directly measures a state fiinction. One still has to consider how this constant-volume heat is measured, perhaps by an electric heater , but then is this not really work Conventionally, however, if work is restricted to pressure-volume work, any remaining contribution to the energy transfers can be called heat . 

If there are other kinds of work, similar expressions apply. For example, with electromagnetic work (equation (A2.1.8)1 instead of pressure-volume work, one can write for the Helmholtz free energy... 

In the broadest sense, thermodynamics is concerned with mathematical relationships that describe equiUbrium conditions as well as transformations of energy from one form to another. Many chemical properties and parameters of engineering significance have origins in the mathematical expressions of the first and second laws and accompanying definitions. Particularly important are those fundamental equations which connect thermodynamic state functions to real-world, measurable properties such as pressure, volume, temperature, and heat capacity (1 3) (see also Thermodynamic properties). 

Methods have been given for the calculation of the pressure drop for the flow of an incompressible fluid and for a compressible fluid which behaves as an ideal gas. If the fluid is compressible and deviations from the ideal gas law are appreciable, one of the approximate equations of state, such as van der Waals equation, may be used in place of the law PV = nRT to give the relation between temperature, pressure, and volume. Alternatively, if the enthalpy of the gas is known over a range of temperature and pressure, the energy balance, equation 2.56, which involves a term representing the change in the enthalpy, may be employed ... 

These relationships interrelate the parameters pressure, volume and temperature with the Gibbs free energy of a system. It may be pointed out that the results embodied in these equations are applicable to closed systems only. 

The preceding calculations can also be performed for finite cavity sizes. For this case, there are some additional sources of small amounts of energy associated with cavity formation arising from surface tension, pressure-volume work, and electrostriction. Because of the Franck-Condon principle these do not affect the transition energy, but they have some influence on the heat of solvation. Jortner s (1964) results are summarized as follows ... 

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