Open Systems

[LibreEnergia]

While I greatly prefer to work in SI units, scaling is just nuisance arithmetic.  In 142 he seemed to be saying he thinks it is necessary to integrate to find total force.  That would make sense if one were trying to find stress on a joint.

I'm not entirely sure what he meant. In an ideal gas at a single point the forces are exerted equally in all directions so it is sufficient to use force divided by area. I've never come across having to use the integral in most engineering analysis.

Perhaps atmospheric processes where the pressure varies with altitude would be an example where you would.

[MarkE]

I'm not entirely sure what he meant. In an ideal gas at a single point the forces are exerted equally in all directions so it is sufficient to use force divided by area. I've never come across having to use the integral in most engineering analysis.

Perhaps atmospheric processes where the pressure varies with altitude would be an example where you would.

He might be thinking of the case of a vessel filled with dense fluid and not a low density gas.

[tinman]

I'm sure there are much better refrigerants than 'HH0', which doesn't actually exist in that form anyway. The gas is H2 and O2 and it combines back to H20.  Since that process is at most 70% efficient for a round trip then you'd be far better off using something else as the working fluid.

Like ammonia etc.

Libre
You really need to go back to the start a d read the thread, and the accounted for energy during the electrolysis process. The system is designed to produce heat, and it dose that at 100% efficiancy-all systems are 100% efficient when all output energies are accounted for.
We do work with units of force, but to simplify we use the psi units-either is correct.

[LibreEnergia]

Libre
You really need to go back to the start a d read the thread, and the accounted for energy during the electrolysis process. The system is designed to produce heat, and it dose that at 100% efficiancy-all systems are 100% efficient when all output energies are accounted for.
We do work with units of force, but to simplify we use the psi units-either is correct.

I just don't see the point in using electrolysis when another substance undergoing a phase change would be more efficient. It is just unnecessary complication.  If it designed to produce heat as you say then the co-efficient of performance would be higher using something else.

[tinman]

Tinman:

I have been doing this stuff in my head mostly, trying to rely on my wits.  I have looked at formulas from time to time but it's mostly from thinking through the problem.

Going back to the transparent cylinder with the piston, I said that if you let the heat escape from the compressed gas first, and then let the piston return by itself, it would not return all the way back in one stroke. It would slowly creep back last 1/4 of the way.  We are assuming the plunger is frictionless, but otherwise it's a real bench setup.

Do you agree with that?  If yes, when the piston stops after moving 3/4 of the way back to the start position, what is the temperature of the gas?

MileHigh
MH
I ask once again that you read the thread from the star and study the system setup. The system is in an insulated room, and when opperating temperatures are reached there is no temperature difference between the gas inside the cylinder and the external enviromental temperature-the heat simply cannot dissipate-Elvis simply can not leave the building-the door is locked-the system is an enclosed system, and the energy remains within that system. It comes down to this-do you want to look at what is really taking place within my system, or do you want to play with a cylinder that is open to the enviroment where its internal energy can be transfered to. Remember MH, energy can be transfered or transformed-not just up and disappear.