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First. 15MPa is not 15bar. It is more like, 150bar. That was the reason I asked the question to begin with. The ONLY factor that causes efficiency losses just by moving fluid back and forth. When you talk about 'efficiency losses', you are also implying that substantial amount of work was created; b...

To my newbie eyes, it appears that the hot side conducts too much heat to the cool side and robs power.

Thermal short.

The gamma engines look very much like alpha riders.

Flow friction is not something you should ignore. We are not talking about hobby/toy models. We talk about engine with 150 bar pressure and high rpm. Density of the gas is dramatically increased and it has to travel on high velocities. Making thermodynamic model as real as possible it is easy to se...

I can't add to my previous post; but here is.......

Narrow pipes mean higher surface area and faster cooling/heating,

Actually, small pipes have very little contact area since it is limited by the ID. The best way is to force air through many very arrow gaps of heating plates.

Small tubes are fine as long as you have many and short. One of things most stirling builders don't concern about is the way heater and cooler are layout. Remember, the working fluid is only heated up/cooled down during the time when it is in the tubes. Once it is out of the tubes, it no longer gets...

@Trevor. I don't see why not. You need to do the calculation so the minimum amount of power for the fan and pump is used. You might want to keep the water temperature as high as possible to increase efficiency, and that means the temperature of the fluid in the cold cylinder is above (way above) tha...

You can ask Andy Ross if he will sell you a plan. This engine of his can go up to 300w
[youtube]https://www.youtube.com/watch?v=BlI3_QoU3Rs[/youtube]

People in general cannot wrap their heads around the idea of "Cold is Power". There is a lot of heat energy flowing around in the atmosphere if the other side is absolution 0. Cooling is a lot more difficult to do than heating. On the hot end, you can create a larger temperature gradient b...

I have been following Kirk's stirling development for years. It would be nice for him to show us more information on his engine such as the size of the slot, dead space volume, sniffing valves, and etc so we can do a compete analysis on it. Most of he stirling engines I have seen have undefined flui...

Look at the way he created the slots. It can be done with a DMLS. The slots can be much narrower and more slots can be made on the heater without increase of dead volume.
https://www.youtube.com/watch?v=lo0opKo5_TQ&t=11s

That is absolutely more important than the hot side and there is no information on the report.

Read through the Mod II report a few times. I still can't wrap around my head that it needs 15MPa to get 56kw. The only things I can think about are 1) internal heater contact area is too small and 2) combustion temperature is not high enough. Any other thoughts?

Having been absent for a while. Seen some interesting activity here. How is everyone doing? Tubular design is not that efficient. With the small diameter of the tube, the effective contact area is very small. Too increase the contact area, either bigger tubes or more tubes can be use, but that also ...

I agree with ishalkhan. Depending on compression. In general, the contact area of the cooler should be at the very least 1.5 times that of heater and long length separation between the two to lessen the effect of thermal short.

The amount of lost caused between the piston and the cylinder is the same, regardless of RPM. So shorter stroke, higher RPM. The other consideration is aerodynamic pumping lost which is generally higher if RPM is higher. As for predicting the RPM of an engine. It can get very high when there is no l...