Timeline for At what stage in the Carnot cycle, does a Carnot engine produce work?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Aug 2 at 0:52 | vote | accept | cookiecainsy | ||
| Aug 1 at 19:30 | comment | added | hyportnex | If the flywheel is the only work reservoir to which the piston is coupled then in the compression stage the flywheel must supply the work from its own rotational energy. The difference between the total supplied work to and total absorbed work by the fly-wheel per cycle is equal to $\Delta S(T_{high}-T_{\ell ow})$ where $\Delta S$ is the entropy absorbed at $T_{high}$ and rejected at $T_{\ell low}$ by the engine. | |
| Aug 1 at 17:00 | comment | added | Chemomechanics | That’s more of a gearing/linkage question than a Carnot engine question. The piston moves in and out every cycle (with a varying force); the details of how to use this motion to run machinery, for example, is up to the user. | |
| Aug 1 at 16:08 | comment | added | cookiecainsy | @Chemomechanics Thanks, that makes sense, however I don't really understand where the work is going. Let's say for example that the piston is connected to a flywheel, if the force exerted by the gas on the piston does not change, the flywheel will not gain energy through each completed cycle | |
| Aug 1 at 0:20 | answer | added | Bob D | timeline score: 2 | |
| Jul 31 at 22:38 | comment | added | Chemomechanics | Yes. Expansion work involves some nonzero (but not necessarily constant) pressure and a nonzero change in volume. In addition, no fine-tuning of the piston movement is required except that it be slow enough to readily allow heat transfer and minimize frictional dissipation. Being exposed to a heat reservoir is enough to ensure that the system tends to that temperature automatically. | |
| Jul 31 at 22:36 | comment | added | cookiecainsy | ahh so are you saying work is done by the system, regardless of whether or not the force it exerts on the piston changes? | |
| Jul 31 at 22:33 | comment | added | Chemomechanics | A review of expansion work $\int P\,dV$ would be useful. Work is done by a system any time it expands against a retreating boundary. It doesn’t matter if the temperature is changing or fixed. The work corresponds to the area under the pressure–volume curve. Work is done by the gas in steps 1 and 2, as confirmed by the positive areas under these curves. Please clarify what is unclear. | |
| Jul 31 at 22:19 | history | asked | cookiecainsy | CC BY-SA 4.0 |