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A process during which the entropy remains constant is called an isentropic process, written = or =. [12] Some examples of theoretically isentropic thermodynamic devices are pumps, gas compressors, turbines, nozzles, and diffusers.
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).
In an isenthalpic process, the enthalpy is constant. [2] A horizontal line in the diagram represents an isenthalpic process. A vertical line in the h–s chart represents an isentropic process. The process 3–4 in a Rankine cycle is isentropic when the steam turbine is said to be an ideal one. So the expansion process in a turbine can be ...
During an isentropic expansion process the working fluid always ends in the two-phase (also called wet) zone, if it is a wet-type fluid. If the fluid is of dry-type, the isentropic expansion necessarily ends in the superheated (also called dry) steam zone. If the working fluid is of isentropic-type, after an isentropic expansion process the ...
In this particular example, processes 1 and 3 are isothermal, whereas processes 2 and 4 are isochoric. 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.
The reason that T = 0 cannot be reached according to the third law is explained as follows: Suppose that the temperature of a substance can be reduced in an isentropic process by changing the parameter X from X 2 to X 1. One can think of a multistage nuclear demagnetization setup where a magnetic field is switched on and off in a controlled way ...
The isentropic stagnation state is the state a flowing fluid would attain if it underwent a reversible adiabatic deceleration to zero velocity. There are both actual and the isentropic stagnation states for a typical gas or vapor. Sometimes it is advantageous to make a distinction between the actual and the isentropic stagnation states.
Example of a real system modelled by an idealized process: PV and TS diagrams of a Brayton cycle mapped to actual processes of a gas turbine engine 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 ]