# How to determine the torque and rpm of a Stirling engine?

I am actually working on making of a Stirling engine. I did some research work but most of the content on the internet is qualitative. So I am trying to build a small scale Stirling engine and trying to gather knowledge through trial and error way.

But since this is not my field of expertise so I thought to raise the question to the community first.

Suppose there is a Stirling engine whose Tcold is 0-degree Celsius and Thot is 200-degree Celsius. The piston is 35mm in diameter and the stroke is 24mm. The engine is made to run using air at a pressure of 2 bar.

Can anyone help me to determine the torque and rpm of this engine?

• Perhaps because other tags are more than relevant. Dec 20, 2020 at 15:03

It will be determined by the system load and internal friction factors.

Here's some initial thoughts on how to determien this:

Your power, $$P$$, is equal to the product of the torque, $$\tau$$ and your angular velocity, $$\omega$$,

$$P = \tau \omega.$$

Assuming a completely adiabatic system, $$\dot Q = P,$$ where $$\dot Q$$ is your heat in.

Therefore, you'd be able to write,

$$\tau = \frac{\dot Q}{\omega}.$$

Now, what you need to know from your system is, $$\omega = f(\tau)$$. how much torque is required to produce a certain angular velocity. Once you know this, the intersection of the two curves give you your operating point.

• one of the curve is w=f(torque) but what is the other curve?
– Tank
Dec 22, 2020 at 6:12
• It's the curve of the system. How much torque is required to produce a certain rotational velocity. This can be measured or derived through system modeling. It should be noted, this would only be for steady state analysis. Transient analysis is another matter. Dec 22, 2020 at 20:22