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E.g. throttling from 200 bar and 300 K (point a in fig. 2) follows the isenthalpic (line of constant specific enthalpy) of 430 kJ/kg. At 1 bar it results in point b which has a temperature of 270 K. So throttling from 200 bar to 1 bar gives a cooling from room temperature to below the freezing point of water.
The throttling process is a good example of an isoenthalpic process in which significant changes in pressure and temperature can occur to the fluid, and yet the net sum the associated terms in the energy balance is null, thus rendering the transformation isoenthalpic. The lifting of a relief (or safety) valve on a pressure vessel is an example ...
The path or series of states through which a system passes from an initial equilibrium state to a final equilibrium state [1] and can be viewed graphically on a pressure-volume (P-V), pressure-temperature (P-T), and temperature-entropy (T-s) diagrams. [2] There are an infinite number of possible paths from an initial point to an end point in a ...
[1] Working fluids are often categorized on the basis of the shape of their T–s diagram. An isentropic process is depicted as a vertical line on a T–s diagram, whereas an isothermal process is a horizontal line. [2] Example T–s diagram for a thermodynamic cycle taking place between a hot reservoir (T H) and a cold reservoir (T C).
An example of a cycle of idealized thermodynamic processes which make up the Stirling cycle. A quasi-static thermodynamic process can be visualized by graphically plotting the path of idealized changes to the system's state variables. In the example, a cycle consisting of four quasi-static processes is shown.
As an example, consider the conjugate pair. The pressure acts as a generalized force – pressure differences force a change in volume, and their product is the energy lost by the system due to mechanical work. Pressure is the driving force, volume is the associated displacement, and the two form a pair of conjugate variables.
The flash evaporation of a single-component liquid is an isenthalpic process and is often referred to as an adiabatic flash. The following equation, derived from a simple heat balance around the throttling valve or device, is used to predict how much of a single-component liquid is vaporized.
The difference between an idealized cycle and actual performance may be significant. [2] For example, the following images illustrate the differences in work output predicted by an ideal Stirling cycle and the actual performance of a Stirling engine: