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The Brayton cycle, also known as the Joule cycle, is a thermodynamic cycle that describes the operation of certain heat engines that have air or some other gas as their working fluid. It is characterized by isentropic compression and expansion, and isobaric heat addition and rejection, though practical engines have adiabatic rather than ...
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 ...
A PV diagram plots the change in pressure P with respect to volume V for some process or processes. Typically in thermodynamics, the set of processes forms a cycle, so that upon completion of the cycle there has been no net change in state of the system; i.e. the device returns to the starting pressure and volume.
PV work is often measured in units of litre-atmospheres where 1 L·atm = 101.325 J. However, the litre-atmosphere is not a recognized unit in the SI system of units, which measures P in pascals (Pa), V in m 3, and PV in joules (J), where 1 J = 1 Pa·m 3. PV work is an important topic in chemical thermodynamics.
T–s (entropy vs. temperature) diagram of an isentropic process, which is a vertical line segment. The entropy of a given mass does not change during a process that is internally reversible and adiabatic.
The PV diagram is a particularly useful visualization of a quasi-static process, because the area under the curve of a process is the amount of work done by the system during that process. Thus work is considered to be a process variable , as its exact value depends on the particular path taken between the start and end points of the process.
The basic scheme of the IBC and temperature-enthalpy diagram are presented in figures 1 and 2. [4] For external heat sources or high temperature storage systems, the closed process design of the inverted Brayton Cycle is also possible. The overall efficiency can thus be significantly increased. [5]
Figure 1: Idealized pressure–volume diagram featuring cardiac cycle components. Real-time left ventricular (LV) pressure–volume loops provide a framework for understanding cardiac mechanics in experimental animals and humans. Such loops can be generated by real-time measurement of pressure and volume within the left ventricle.