Cv[constant volume] = 20.7 J/mol K, or at
Cp[constant pressure] = 29.0 J/mol K
| Finally we will talk about cyclic processes. For simplicity choose 4.5
moles of an ideal gas of air for which I know the specific heats when the
air is kept at Cv[constant volume] = 20.7 J/mol K, or at Cp[constant pressure] = 29.0 J/mol K |
|
Three processes may be examined, ABCDA, ABCA, and ACDA. We will begin with ABCDA.
At point A the volume is 0.50 m3 and the pressure is 150 kPa, at
point C the volume is 1.95 m3 and the pressure is 22.3 kPa.
(a) Find the temperature, pressure, and volume at each of the lettered
points. Make a neat table.
(b) Find the work, heat, and change in internal energy for each of the
processes AB, BC, etc. Make a table.
(c) Find the net work done in one cycle.
(d) You pay money for the heat source that provides Q that is positive.
The exhaust is generally free (exhaust to the air, or to cooling water.) Find
the efficiency defined as net work done divided by heat paid for.