Mechanical Engineering Thermodynamics - Lec 16, pt 6 of 6: Stirling Engine Operation

[@ken-cf7tf]

at 10:18, the piston on the cold side should be LOWER than the TDC. That is, the volume at state 4 should be lower than the volume at state 3, because the fluid is compressed at constant temperature(T_L). You can easily see this on the Pv graph.

[@abdallahalkateeb9537]

hope you are my doctor, keep doing these tutorial and thank you so much it is really helpful.

[@joevignolor4u949]

The Swedish have a submarine that uses a Sterling engine. It burns kerosene along with liquid oxygen. The HSMS Gotland can stay submerged for up to two weeks and it's very quiet.

[@00PedroM]

Great video, but there are some things I don´t quite understand well - Do the cylinders have always a temperatura gradient? I mean, is one of them always the "cold" one and the other the "hot" one? From my intuition, when the gas passes through the regenerator, if the regenerator is storing thermal energy, the gas would heat up independent of the side of it´s flow. It´s difficult for me to understand why it heats up only (in this case) when going from left to right, and cools when going from right to left, assuming the regenerator is always hot. Anyway, thanks!

[@steveforbin911]

I am confused point 4 to 1 is where the heat goes in pressure goes up as heat goes in . and 1 to 2 is the power out as this gas is expanding. 2 to 3 is atmospheric push back so that is what is doing the work power from atmosphere.

[@jimtwisted1984]

Watching a fan with some road noise in the background is a real learning experience.

[@owaisaqtash]

HI there, do you have a video explaining the mathematical model of the stirling engine? if not could you pleas lead me to one because i really need it thank you

[@seditiousmonkeyart]

Hi, Great explanation of the thermodynamic processes but your explanation and diagrams have an error from a mechanical perspective. Stirling engine displacer (hot) and power (cold) pistons are phased 90 degrees apart, not 180 degrees. This means the the displacer piston and the power piston can never be at their TDC and BDC simultaneously. When one is at its TDC or BDC the other piston will be half way through its stroke (either up or down). This is an aspect of the thermodynamics of the stirling has challenged me, especially the Carnot cycle as it seems to be out of sync with the true mechanical workings of the engine. If you are compensating for the fact that the expansion and contraction processes are progressive through the rotation of the crank and the 90 degree phasing please forgive me.

[@steveforbin911]

Great point ...

[@nyx211]

This is an example of an *ideal* Stirling engine, which is only theoretical. This engine has two power pistons and no displacer piston, but the displacement of gas from one cylinder to the other occurs during the constant volume processes (2->3 and 4->1). Similarly, a Carnot engine is a "perfect" heat engine and only exists on paper. A real Stirling engine doesn't have constant volume processes in its cycle nor does it keep one piston fixed while the other one moves. This means that a real Stirling engine has a PV diagram that looks more like an oval.

[@Jouni2]

Normally there is one displacer and one power piston. Two power pistons arrangement has a problem. Gas pressure is getting lower already, when the gas is flowing to the gold piston. Then 1-2 goes too fast down (pressure dropping). The gas is heatening when flowing to the hot piston and the pressure is rising too early and the pressure is risening too fast (3-4). The energy out per one cycle is positive work 1-2 minus negative work 3-4 = the area 1-2-3-4-1 = PxV. 1 N/m2 x 1 m3 = 1 Nm = 1 J = 1 Ws. Now the area becomes too small. The normal stirling has Qin:4-1 (pressure rising) and Qout:2-3 (pressure down). In an ideal case Q happens when the gas flow has stopped.

[@mungewell]

Replying to 6year old comment. Remember that TDC and BDC are from sinusoidal motion, and are practically spread out in time. Pistons are not 180, and therefore one can be (effectively) stationary as the other is moving.

[@j120772]

Great video, thank you sir for explaining the "pro-cesses," reminds me of my good friends dialect from northern Maine lol. I am uncertain of the design/ workings of the expansion mechanism. I am thinking some type of reed valves would be needed for this to work, my plan is to research that more thoroughly. Thank you again for your knowledge and sharing that information.

[@anavillalobos3476]

Reed significado en español

[@VshalBM]

Process 3- 4 piston in hot side fixed at BDC and piston from cold side starts at TDC doing compression. Then how it's possible in process 4-1 that the piston in a cold side will start from TDC , as in process 3-4 compression takes place in cold side.

[@user-qj3rv2mo1b]

Could u also use the first, second law and of thermodynamics (TS & PV) and solve few problems to make it more exciting? Thank u,

[@abolbeil-9980]

thank you

[@moustafashafik9221]

At the 4th process (4 to 1) the cold piston should be at the BDC since the process happens at the lower volume and after compression happened

[@ken-cf7tf]

No, it should not be all the way down at BDC. It should be at the same level as in the left piston at state 1, since V1 = V4.

[@user-qj3rv2mo1b]

How is air transferred to the second cylinder? How the regenerator stored heat is used? Could u explain the regenerator works? Thank u

[@ladieman050893]

thanks prof

[@user-qj3rv2mo1b]

Could u also do a video of sterling cycle and refrigeration or heat pump? Thank u

[@user-qj3rv2mo1b]

In the constant volume processes 2-3 & 4-1, the sum of the volumes in the two cylinders remain constant after simultaneous volume increase & decrease & temperature decrease & increase in the two cylinders respectively? In the constant volume processes, temperature decreases in the first cylinder only because the heat goes into a regenerator? And the temp of the second cylinder ends up becoming higher than the first cylinder? Is there any transfer of heat between the generator and the second cylinder? Thank u

[@boscovich11]

U can spin it from the flywheel directly not from the airfoils.

[@2112dim]

What a helpful and efficient analysis, thank you so much. The constant volume during processes 2-3 and 4-1 refers to the volume of both pistons? Thank you in advance

[@yigitcanbaysal824]

yes it does ,I guess

[@igorp6831]

The pistons of the working Stirling engine that drives fan in the first part of the video are phased at ~90 degrees while the professor claims in his lecture that they are phased at 180 degrees. Apparently the engine with 180 degrees phasing will not work at all.

[@user-qj3rv2mo1b]

Is heat regenerator another name for heat exchanger? How does a regenerator work?

[@bbbswart]

Oke, but what does the regulator consist of?f What is it? A valve or something?

[@annazriarnanda2354]

hi i am from a student from indonesia i am working on a thesis about the gamma type stirling engine i have a question about you whether the diameter of the displacement piston has a diameter difference with the displaser cylinder

[@larsandersen8800]

😁👍

[@GiovaniMoreiraG]

0:05 sounds like Donkey Kong

[@danrayson]

At no point is there a constant volume. When the air is passing through the regenerator it's changing its volume because its transferring heat from/to the air. It may have been for diagramming purposes, but it's wrong so. So many variations on these explanations of carnot cycle engines, I can't help but think nobody actually understands them.

[@pekertimulia125]

Ini mah turbo jet

[@pekertimulia125]

Ibarat pepatah orang kata terbang ko kagak pakai mesin..!

[@walterwise935]

"Cooling at a constant temperature" I admire your desire to teach, but some of this is NOT how a Stirling engine works. Plus, your piston function is not really even correct, since the volumetric notions are not similar to a stirling engine. The heated cylinder piston just moves the air from hot end to cold end, it creates no pressure on its own, and does not contribute to the pressure of the system by and large. that is piston 2. Plus it all has to be 90 degrees off, or 270 as the case may be, and this makes no mention of why that is. Please regroup and I'd love to see the new version? you game for that? Let us know!