Search found 3299 matches
- Sat Apr 27, 2024 1:28 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
... If the cycle starts at Qcz, and DQh is added. It is then expanded doing work a maximum of Qhz Joules will be converted to work. The gas will be at T = 0 Kelvin and P=0. Now it must be compressed back to P=atmospheric an Tc=300 K. It will take 300 J to do so. That makes the machine's efficiency ...
- Sat Apr 27, 2024 12:50 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Basically, plain and simply : n=(Qh-Qc)/Qh And : Q=Cv•M•T So : n = (Qh - Qc) / Qh n = (Cv•M•Th - Cv•M•Tc) / Cv•M•Th Simplifying : n = (Cv•M(Th-Tc) / Cv•M•Th Canceling : n = (Th-Tc) / Th If the cycle starts at Qcz, and DQh is added. It is then expanded doing work a maximum of Qhz Joules will be conv...
- Fri Apr 26, 2024 10:24 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Begining of derivation: Taking the above 'noted' equation "Qhz = Qcz + DQh" and subtracting Qcz from both The term 'n' applies to the engine regardless of 'Qcz' base heat amount or reference point. I t will have the same efficiency burning the same energy at the same temperatures but with...
- Fri Apr 26, 2024 3:15 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Begining of derivation: Taking the above 'noted' equation "Qhz = Qcz + DQh" and subtracting Qcz from both The term 'n' applies to the engine regardless of 'Qcz' base heat amount or reference point. It will have the same efficiency burning the same energy at the same temperatures but with ...
- Fri Apr 26, 2024 2:37 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 54
- Views: 460
Re: Isothermal Heat Transfer
Tom, why would the balloon inflate? The gas heats up, expands, pushes the piston outward causing some inflation. The engine then runs. Any leakage by the piston would make the piston run closer to the closed end. The gas going by the piston would cool and return to it's original volume. Hence it wo...
- Fri Apr 26, 2024 11:08 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 54
- Views: 460
Re: Isothermal Heat Transfer
But maybe gas can "stretch" like a rubber band. IDK. But I can see that the piston in a Stirling engine does infact return. Without a flywheel. Without a displacer. With no apparent "sink" or viable heat outlet. I've done the experiments myself, so I can't really just dismiss wh...
- Fri Apr 26, 2024 10:14 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Begining of derivation: Taking the above 'noted' equation "Qhz = Qcz + DQh" and subtracting Qcz from both The term 'n' applies to the engine regardless of 'Qcz' base heat amount or reference point. It will have the same efficiency burning the same energy at the same temperatures but with ...
- Fri Apr 26, 2024 9:49 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
a2+b2=C2 would be pretty useless if it only worked for equilateral triangles. Pythagoras is spinning in his grave. :laugh: There is of course, no such thing as an equilateral right triangle. Which is the point. There is no such thing as a "perfect" Carnot engine either An algebraic formul...
- Fri Apr 26, 2024 9:18 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Thot = 600 Tcold = 300 Qhot = 150 joules You forgot the units, 'Kelvin', for the temperatures. You put temperatures into an energy equation, and mixed them with heat. The reason it worked in the previous example is that DQh and DT were both 100. It had a one to one relationship between energy and t...
- Fri Apr 26, 2024 7:53 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Thot = 600 Tcold = 300 Qhot = 150 joules You forgot the units, 'Kelvin', for the temperatures. You put temperatures into an energy equation, and mixed them with heat. The reason it worked in the previous example is that DQh and DT were both 100. It had a one to one relationship between energy and t...
- Fri Apr 26, 2024 4:17 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Suppose we use my original values ? Thot = Qhz = 600 (but also 450 ?) Tcold = 300 = Qcz Qhot = 150 joules = DQh DQh = Qhz - Qhz(1-n) 150 = 600 - 600(1 - .25) 150 = 600 - 600(0.75) 150 = 600 - 450 150 = 150 Hey, worked out! But elsewhere Qcz + DQh = Qhz Qcz + DQh = Qhz 300 + 600 = 900 So Qhz can equa...
- Fri Apr 26, 2024 3:48 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Can we try some other more "realistic" (in your opinion) values? How about Thot = 600 Tcold = 300 Qhot = 150 joules Anything wrong with those numbers? Equations are supposed to balance right? Isn't that what the equal sign is for? Isn't that what mathematical precision is all about? We ass...
- Fri Apr 26, 2024 2:45 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 363
- Views: 12870
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
2+x=4 What does x equal? X=5 2+5=4 7=4 The equation must be wrong. Give me a break. An equation isn't valid for any numbers you want to put in. An equation is only valid if use properly. It should at least be valid for the potential range of application, don't you think? Or are you presupposing ONL...
- Fri Apr 26, 2024 1:38 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 54
- Views: 460
Re: Isothermal Heat Transfer
But by doing work and loosing energy and getting cold, the gas contracts. By contracting, this allows outside atmospheric pressure to do the work of returning the piston to TDC. The gas by pushing to expand, by pushing, the volume increases, because it was heated to a higher temperature, using that...
- Thu Apr 25, 2024 6:54 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 54
- Views: 460
Re: Isothermal Heat Transfer
From that article I thought this was interesting. Something I haven't seen before: So for 𝑇 > 𝑇inv, an expansion at constant enthalpy increases temperature as the work done by the repulsive interactions of the gas is dominant, and so the change in kinetic energy is positive. But for 𝑇 < 𝑇inv, expans...