18 Due 11/30

Open-ended design question:

How could you, based on your knowledge of efficiencies and thermo, improve the performance of the lab Stirling engine with primarily thermodynamic (as opposed to mechanical) improvements? Discuss in detail. Explain the thermodynamics background behind your proposals clearly.

While your proposed improvement(s) must be thermodynamic in nature to qualify for credit in a thermo class, you must also discuss how to actually make the improvement in the lab engine. Include a design drawing.

Your proposal should be neat and formulated in a logical order: abstract, background, theoretical justification, proposed implementation, with design drawing, and references.

An abstract is not an introduction. It must summarize what your final proposal is, and how it is to be implemented.

All sources used must be referenced and fairly credited for their contributions. You are still responsible for understanding and verifying the claims you find in literature and on the web.

Note that normally performance should be taken to be efficiency. If you take performance to be produced power, the obvious (and correct) answer is: make the engine bigger. That trivial answer gets no credit. What we really want to see is nontrivial, creative (if at all possible), effective, fully explained and researched, improvements. There is some flexibility in what you define as efficiency, but you better argue your case solidly!

Come to think of it, it is your responsibility to convincingly argue, to any reasonably fair grader, that your modifications will work, to a nontrivial extent. It is not up to the grader to prove your idea(s) wrong. It is up to you to prove it/them right. Your evidence must be able to convince even the most sceptical, but scientifically fair, judge.

To do so, please remember two facts from physics: (a) Under the same $P$, $V$, and $T$, different gasses have the same number of molecules (as in $PV=n\bar{R}_uT$). The masses will be different depending on what the molecular mass is. (b) Noble gasses will all have the same kinetic internal energy $\frac{3}{2}k_{\rm {B}}T$ per molecule, (not per unit mass), while diatomic ideal gasses normally have about $\frac{5}{2}k_{\rm {B}}T$ at room temperature. A more complex molecule like water has about $\frac{6}{2}k_{\rm {B}}T$. A flappy (i.e big and flexible) molecule may have much more still.