Well at first we are talking about mod II stirling engine that uses 15MPa= approximately 15bar. That is where I got the number.Aviator168 wrote:
Let's settle on one thing here. We are not talking about toys models. I understand the parasitic drag induced by the connector; but that's a compromise I am willing to make, and why not. It is in direct proportion to heat exchange area. Now a couple of question. Why do you need 150 bar and what rpm and temperatures are you talking about? Have you consider the efficiency losses just moving the air back and forth (regardless of friction losses). For instances, 1 liter of air weights about 1 gram at 1 bar. At 150 bars, it will weight 150 grams. Regardless of rpm, it will take a lot of energy to move 150 grams of working fluid back and forth.
Now to the part of gas moving back and forth. What do you think causes efficiency losses for fluid moving back and forth?? It's flow friction! You can't talk about it excluding flow friction. It is basically The ONLY factor that causes efficiency losses just by moving fluid back and forth. Friction is determined by various factors: viscosity of the gas (obviously it uses helium not air), surface finish of fluid traveling path, fluid traveling speed and various other small factors (example: small radius at the entrance of each tube/passageway in order to minimize “entrance losses”).
GAS(FLUID) TRAVELING THROUGH NARROW PIPES AT HIGH VELOCITIES SUFFER FROM HIGH FRICTION TO WALLS OF THOSE PIPES.
I am very sorry if I am wrong but you don't seem to understand that gas or any fluid is affected by friction when contacting any surface.