# Is there a way by which one could determine the required temperature difference for stirling engine?

I am trying to make a stirling engine. I did some research work and also reviewed some books but the problem is that a great deal of information on this engine is qualitative, rather than quantitative.

I am just curious to know how can we determine the temperature difference(Tmax and T min) on which the stirling engine should be operated to achieve force (F).

Please suggest some resource for stirling engine if any for beginers.

• Check out Carnot efficiency. – Solar Mike Nov 17 '20 at 10:42
• Abs max efficiency = Carnot Efficiency = (Thot-Tcold)/Thot in degrees Kelvin = degrees C + 273.||. A very well built and designed engine with high temperature differentials, high pressure and using Hydrogen (not at all recommended) or Helium working gas might achieve 10% - 50%+ of Carnot efficiency. Less than 10% is easy. More than say 20% is getting hard. || Proper Regenerator design and construction IUTTERLY CRUCIAL for good efficiency. || MUSH needs to be understood to get a good design . Toys are easy . Real power and efficiency is hard. – Russell McMahon Nov 17 '20 at 11:56
• The web has most of what you need. All you need really. || It is vital to know what your targets are and what your manufacturing limits are. How much wattage, what expected size, what application, what tolerable efficiency, fuels, gases pressures temperatures. REAL high power high efficiency designs would usually use Helium at 2000 psi+ and. say 400-600 degrees C (!). Others use air in some real world applications and maybe 100-200 psi. || You are welcome to email me (see my profile) and I can give you some guidelines. – Russell McMahon Nov 17 '20 at 11:56

$$\text{Absolute maximum efficiency} = \text{Carnot Efficiency} = \frac{T_{hot}-T_{cold}}{T_{hot}}$$

where all temperatures are expressed in degrees Kelvin (= degrees C + 273).

A very well built and designed engine with high temperature differentials, high pressure and using Hydrogen (not at all recommended) or Helium working gas might achieve 10% - 50%+ of Carnot efficiency. Less than 10% is easy. More than say 20% is getting hard.

Proper Regenerator design and construction is UTTERLY CRUCIAL for good efficiency. MUCH needs to be understood to get a good design . Toys are easy.
Real power and efficiency is hard.

The web has most of what you need. All you need really.
It is vital to know what your targets are and what your manufacturing limits are, how much wattage, what expected size, what application, what tolerable efficiency, fuels, gases pressures temperatures. If you can give as much detail as possible a far better answer can be given.

REAL high power high efficiency designs would usually use Helium at 2000 psi+ and say 400-600 degrees C (!) (or more). Others, at lower efficiency, use air in some real world applications and maybe 100-200 psi. You are welcome to email me (see my profile) and I can give you some guidelines, but providing substantially more details here will help.

• I researched more about the power of the sterling engine and came across an article which says "In order to transfer heat fast, you must have a large temperature difference. If you have a large temperature difference, you lose the thermal advantage of the Sterling engine. The design is doomed to failure from the start because you can't have the high efficiency AND high specific power at the same time." Can you please explain me this statement. @Russell McMahon – Tank Nov 18 '20 at 9:14
• You can see the article in this link: researchgate.net/post/… – Tank Nov 18 '20 at 9:25
• The comment is rubbish for sensible ranges powers and temperatures. Stirling ( two I's) engines have enough implementation problems compared to other thermodynamic based cycles that they tend to be used only in specialist applications. But when their advantages are more important than the challenges faced they are often the premium solution. The Swedish Gotland class submarines use a 75 kW Stirling engine ton charge their batteries to allow ultra quiet operation. NASA deep space probes use radioisotope powered Stirling engine generators. Philips long ago built Stirling bus engines but the ... – Russell McMahon Nov 18 '20 at 9:30
• ... mechanical challenges were excessive and it corresponded with a period of major diversification by Philips. It very very much friends on why you want to use a Stirling engine. Answer the queries in my answer to get a much better answer. – Russell McMahon Nov 18 '20 at 9:33
• Some useful links via that link. The person who posted that comment has no practical knowledge of the subject. The engine he described was presumably a demonstration example for students. The best machines if the size he described would be far less powerful than an IC engine of the same size but would easily 'tear his arms off" if he tried to stop them in that manner. – Russell McMahon Nov 18 '20 at 9:39