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:
“It is easy to see that what is best written or done by genius in the world, was no man’s work but came by wide social labor, when a thousand wrought like one, sharing the same impulse.”
—Ralph Waldo Emerson (1803–1882)
“There never has been a time in our history when work was so abundant or when wages were as high, whether measured by the currency in which they are paid or by their power to supply the necessaries and comforts of life.”
—Benjamin Harrison (1833–1901)
“Hard work. Well, that’s all right for people who don’t know how to do anything else. It’s all right for people who aren’t lucky. But once you’re lucky, you don’t have to work for other people. You make them work for you.”
—Dan Totheroh (1895–1976)