Thermodynamics: gas for stirling engine + liquid with high density

In summary, the Crazy Noob is trying to build a model stirling engine using balloons and empty catfood cans. She would like advice on what gases and liquids would work best.
  • #1
The Crazy Noob
3
0
Hi,

***
for the ones that don't like to read much (:smile:): the basic point is that I need a gas that gives as much pressure as possible with a temperature increase and a constant volume and that is easy to get my hands on; and a liquid with a high density (like mercury or something) that has a high boiling pont (preferably higher than 100°C), doesn't damage latex and isn't poisenous/dangerous.
***

I plan on building a model stirling engine (an engine that runs on heat) I've searched the web and found a nice, easy, little engine called the RotaColaSola engine, it should work on solar heat. (link: the original one (RotaColaSola) and the improved one (SexBalloon engine).
I would like to build the SexBalloon-type of engine (using balloons, no condoms :tongue: ) and I've started saving tin cans (empty catfood cans) because they are bigger and I have a bigger supply of them :smile:.

Now the actual question-part: While I'm waiting until I've got enough tin cans, I thought of a few improvements:
- If I would use a gas that, given a constant volume, produces more pressure with an equal temperature increase than plain air. (if it's explained badly I'll give an example: if the temperature increases with 10degC, the pressure of gas X increases with 10% while the pressure of regular air only increases with 5% -> twice as much power?) This will cause the liquid in the balloon to be pressed up more which should create more power. (my physics-teacher said something about hydrogen or helium?...)
- If I replace the water with a liquid that has higher density, the difference in weight will be greater when a same amount of liquid is pushed into the other reservoir and thus increasing the power. (example: if 1cc of water is moved, the weight that is moved is 1gram; if 1cc of liquid X is moved, the weight that is moved is equal to 2grams -> twice the power?) *note*: the boiling temperature would need to be as high as possible (the liquid must stay a liquid when heated with sun or with candle/flame/...)


I know that this forum is packed with physics-geniouses :wink: so if someone could please confirm the above or give other advice...
And does anyone know gasses and liquids that meet the above requirements, are easy to get and aren't dangerous?



Thanks,

The Crazy Noob
 
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  • #2
Just make a very concentrated solution of NaCl will be very dense and has pretty much infinite solubility so you can make it as dense as you like. Don't really know anything about gases off hand though.
 
  • #3
omagdon7 said:
Just make a very concentrated solution of NaCl will be very dense and has pretty much infinite solubility so you can make it as dense as you like. Don't really know anything about gases off hand though.
lol, that just sounds so logical, can't believe i didn't think of that :blushing: :smile: (btw: the density of NaCl is 2.17 g/cm3, but i could use annything that is soluble in water...)

Thanks for the tip, now i just need a gas :smile:
 
  • #4
** bump **
 

1. What is the role of gas in a Stirling engine?

The gas in a Stirling engine serves as the working fluid that undergoes a thermodynamic cycle, converting heat energy into mechanical work. It expands and contracts inside the engine, pushing the pistons and driving the engine's motion.

2. How does the gas used affect the efficiency of a Stirling engine?

The type of gas used in a Stirling engine can greatly impact its efficiency. Ideal gases with a high heat capacity, such as helium or hydrogen, are commonly used because they can undergo large temperature changes without reaching extreme pressures. This allows for a more efficient thermodynamic cycle.

3. Why is a liquid with high density preferred for Stirling engine applications?

In Stirling engines, the liquid is used to transfer heat from the hot to the cold side of the engine. A liquid with high density, such as water or oil, can carry a larger amount of heat per unit volume, making it more effective in transferring heat and improving the engine's efficiency.

4. Can any type of gas and liquid be used in a Stirling engine?

There are many factors to consider when choosing the gas and liquid for a Stirling engine, such as temperature range, heat capacity, and availability. While some gases and liquids may work in theory, they may not be practical or cost-effective for real-world applications.

5. How does thermodynamics play a role in the function of a Stirling engine?

Thermodynamics is the branch of science that deals with the conversion of heat energy into mechanical work. In a Stirling engine, it governs the principles of heat transfer, gas behavior, and energy conversion that allow the engine to function and produce useful work.

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