Adiabatic Compression and Expansion

The air spring effect results from adiabatic expansion and compression of the air in the actuator casing, Niirnericallv, the small perturbation value for air spring stiffness in Newtons/rneter is given bv Eq, (8-107),... 

The adiabatic expansion and compression serve only to change the temperature of tire gas widrout heat being absorbed or evolved, i.e. iso-entropic changes. The heat changes are therefore only related to the work which is done during the isothermal stages, which is given by... 

Fig. 3 In C0NFL03, the inlet pressure was changed at time = 300 s from 150 to 200 kN/m2. Seen here are the temperature and pressure effects of the adiabatic expansion and compression.

In Fig. 8, step I is an isothermal expansion, step II is an adiabatic expansion, step III is an isothermal compression, and step IV is an adiabatic compression. Note that zero heat is transferred in the adiabatic expansion and compression (steps II and IV) that we have added to complete the cycle, and that the work terms in these two steps exactly cancel, being equal to TC Cv dT in the expansion and Th Cv dT in the compression. (The work in an adiabatic... 

For gases, this derivative is positive. It applies to reversible adiabatic expansions and compressions in turbines and compressors. 

The graphs for enthalpy also contain lines of constant entropy to permit engineering usage for 2nd law problems such as adiabatic expansion and compression of fluids. 

Figure 3.19 on the next page shows indicator diagrams for adiabatic expansion and compression with internal friction. The solid curves are for irreversible processes at finite rates, and the dashed curves are for reversible processes with the same initial states as the irreversible processes. The areas under the curves confirm that the work for expansion is less... 

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