Science Buddies: "Ask an Expert"

In order to simulate increasing ambient pressure of a fueled Stirling engine, I am increasing the pressure of both ends of the engine by an equal amount, keeping the temperature differential constant.

However, the temperature reading from my thermometer when I measure the hot and cold ends keeps fluctuating.
Is there any way to prevent this?

Or is it a flaw in the thermometer? I had a similar problem before with multimeters, but it worked when I attached an alligator clip.

Hi stufffandthings,

To answer your question, I'm going to need some additional information. For example, what kind of thermometer are you using (bulb, infrared, thermocouple, etc.)? What is the thermometer in contact with on the two ends of the engine? How large are the fluctuations (e.g., +/0 0.1 degrees, 1 degree, 10 degrees, etc.)? Is it possible that the temperature actually is fluctuating? What is the timescale of the fluctuations (e.g., seconds, minutes, hours, etc.)? The answers to these questions will help us help you. The more detail you can provide, the better we will be able to help you.

I was able to soon fix the problem. I don't know why, but it simply stopped fluctuating.

Hi stuffandthings,

I'm glad your problem resolved itself!