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
Read more about this topic: Working Fluid
Famous quotes containing the word work:
“... possibly there is no needful occupation which is wholly unbeautiful. The beauty of work depends upon the way we meet it—whether we arm ourselves each morning to attack it as an enemy that must be vanquished before night comes, or whether we open our eyes with the sunrise to welcome it as an approaching friend who will keep us delightful company all day, and who will make us feel, at evening, that the day was well worth its fatigues.”
—Lucy Larcom (1824–1893)
“Memory is a wonderfully useful tool, and without it judgement does its work with difficulty; it is entirely lacking in me.... Now, the more I distrust my memory, the more confused it becomes. It serves me better by chance encounter; I have to solicit it nonchalantly. For if I press it, it is stunned; and once it has begun to totter, the more I probe it, the more it gets mixed up and embarrassed. It serves me at its own time, not at mine.”
—Michel de Montaigne (1533–1592)
“Come, heart, where hill is heaped upon hill:
For there the mystical brotherhood
Of sun and moon and hollow and wood
And river and stream work out their will....”
—William Butler Yeats (1865–1939)