Work
The working fluid can be used to output useful work if used in a turbine. Also, in thermodynamic cycles energy may be input to the working fluid by means of a compressor. The mathematical formulation for this may be quite simple if we consider a cylinder in which a working fluid resides. A piston is used to input useful work to the fluid. From mechanics, the work done from state 1 to state 2 of the process is given by
Where ds is the incremental distance from one state to the next and F is the force applied. The negative sign is introduced since in this case a decrease in volume is being considered. The situation is shown in the figure which follows.
The force is given by the product of the pressure in the cylinder and its cross sectional area such that
Where A.ds = dV is the elemental change of cylinder volume. If from state 1 to 2 the volume increases then the working fluid actually does work on its surroundings and this is commonly denoted by a negative work. If the volume decreases the work is positive. By the definition given with the above integral the work done is represented by the area under a pressure - volume diagram. If we consider the case where we have a constant pressure process then the work is simply given by
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Famous quotes containing the word work:
“How dare I read Washington’s campaigns, when I have not answered the letters of my own correspondents? Is not that a just objection to much of our reading? It is a pusillanimous desertion of our work to gaze after our neighbours. It is peeping.”
—Ralph Waldo Emerson (1803–1882)
“We work to eat to get the strength to work to eat to get the strength to work to eat to get the strength to work to eat to get the strength to work.”
—John Dos Passos (1896–1970)
“If therefore my work is negative, irreligious, atheistic, let it be remembered that atheism—at least in the sense of this work—is the secret of religion itself; that religion itself, not indeed on the surface, but fundamentally, not in intention or according to its own supposition, but in its heart, in its essence, believes in nothing else than the truth and divinity of human nature.”
—Ludwig Feuerbach (1804–1872)