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:
“‘Men work together,’ I told him from the heart,
‘Whether they work together or apart.’”
—Robert Frost (1874–1963)
“The press is no substitute for institutions. It is like the beam of a searchlight that moves restlessly about, bringing one episode and then another out of darkness into vision. Men cannot do the work of the world by this light alone. They cannot govern society by episodes, incidents, and eruptions. It is only when they work by a steady light of their own, that the press, when it is turned upon them, reveals a situation intelligible enough for a popular decision.”
—Walter Lippmann (1889–1974)
“The slightest living thing answers a deeper need than all the works of man because it is transitory. It has an evanescence of life, or growth, or change: it passes, as we do, from one stage to the another, from darkness to darkness, into a distance where we, too, vanish out of sight. A work of art is static; and its value and its weakness lie in being so: but the tuft of grass and the clouds above it belong to our own travelling brotherhood.”
—Freya Stark (b. 1893–1993)