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:
“Obvious enough that generalities work to protect the mind from the great outdoors; is it possible that this was in fact their first purpose?”
—Howard Nemerov (1920–1991)
“All in all, the creative act is not performed by the artist alone; the spectator brings the work in contact with the external world by deciphering and interpreting its inner qualifications and thus adds his contribution to the creative act. This becomes even more obvious when posterity gives its final verdict and sometimes rehabilitates forgotten artists.”
—Marcel Duchamp (1887–1968)
“But he had gone his way, the grass all mown,
And I must be, as he had been,—alone,
‘As all must be,’ I said within my heart,
‘Whether they work together or apart.’”
—Robert Frost (1874–1963)