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In thermodynamics, an isochoric process, also called a constant-volume process, an isovolumetric process, or an isometric process, is a thermodynamic process during which the volume of the closed system undergoing such a process remains constant. An isochoric process is exemplified by the heating or the cooling of the contents of a sealed ...
An isochoric process however operates at a constant-volume, thus no work can be produced. Many other thermodynamic processes will result in a change in volume. A polytropic process , in particular, causes changes to the system so that the quantity p V n {\displaystyle pV^{n}} is constant (where p {\displaystyle p} is pressure, V {\displaystyle ...
According to the first section above, an heating for a solid can not be a isochoric, so the pressure change in a non-isochoric heating process is not exactly the thermal pressure. When a solid is loaded with a pressure gauge, and heated/compressed together at high P - T , the thermal pressure of the solid does not equal that of its gauge.
The work done in a process is the area beneath the process path on a P-V diagram. Figure 2 If the process is isobaric, then the work done on the piston is easily calculated. For example, if the gas expands slowly against the piston, the work done by the gas to raise the piston is the force F times the distance d.
As defined earlier, an incompressible (isochoric) flow is the one in which = This is equivalent to saying that = + = i.e. the material derivative of the density is zero. Thus if one follows a material element, its mass density remains constant.
In some cases, when analyzing a thermodynamic process, one can assume that each intermediate state in the process is at equilibrium. Such a process is called quasistatic. [4] For a process to be reversible, each step in the process must be reversible. For a step in a process to be reversible, the system must be in equilibrium throughout the step.
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".
Thermodynamic cycles may be used to model real devices and systems, typically by making a series of assumptions to reduce the problem to a more manageable form. [2] For example, as shown in the figure, devices such a gas turbine or jet engine can be modeled as a Brayton cycle. The actual device is made up of a series of stages, each of which is ...