Freon Engine

Refrigerant comes in a cylinder. What are you really doing? CFM is a measure of volume.

To do the same amount of work, the 80PSI cylinder/piston would need to be larger.

I don't think this answers your question.

I figured the volume of the cylinder. This figure is zero pressure. If I were to push my piston with gas I would need to raise the pressure which would take several cylinder volumes of gas. Would it take the same increase in volume at 100 psi as it would take at zero psi to do the same work? I am making a one cylinder low temperature engine running on sunshine for now. Thanks for your thoughts, Nick

Nick,

Let me put it this way. A higher pressure will require more volume of gas or higher temperature gas.

Since the volume of your cylinder is constant, you either have to push more gas in at ambient temperature or heat the existing gas to excite those molecules.

The question is not very meaningful unless it tells what is to be held constant and what may vary.

Perhaps the OP is working on something like this?

That is cool!

Thanks, Anon, that is very interesting.

I was wondering if something similar could work where you have high temp solar heater and cold underground or underwater areas nearby to act as the heat sink. In Alaska they are using geothermal heat, perhaps in the Virgin Islands, or the Mediterranean solar could heat it and the water cool?

Possibly. I'm sure you could use solar-heated water in the evaporator vessel (theirs is only at 165F), but I don't know if mediterranean water (or other source) would be cold enough for the condensor vessel (theirs is 40F). Probably not, and I don't know if you'd find a cold enough source, but then I'm no expert in this stuff, just interested.

I think you are right as it is the potential that is important. Solar collectors can get water to 100 deg c and the ground itself may be able to cool to 25 deg c especially if the pipework is in the groundwater. The article mentions a diferential of 100 deg f is required, if my math is o.k. that is 56 deg c and so it's doable.

If the 'solar collector system' can generate a high enough Q rate ... (I meant transfer not generate) ... then ... get a Fresnel lens and run a sterling to transfer solar nrg into electric nrg via a 'generator'. A lot simpler.

But the 2 temp geo-thermal will run at night so it has an advantage there.

My answer is based on the assumption you are blowing compressed gas into a single cylinder reciprocating engine.

Assuming the cylinder and piston are the same, and speed is the same, then the cfm would be the same. However, with higher pressure gas, you would get more work from the higher pressure gas.

Assuming the load on the engine is identical, the higher pressure gas would turn the load faster than the low pressure gas.

That's my best guess. Can you give more details of what you are trying to do?

Thank you all for the help and wish me luck. Nick

Which Freon gas? Before you design check its ODP Ozone depleting potential from Environmental consideration.

"Freon" is the trade name of "Dupont". There are several dozen type of refrigerants out there, and not just by "Dupont"

All refrigerants have a identifier standard such as R-12, R-22 etc. Or the chemical formulation on the container it came in.

In order to start any responses I need to know what refrigerant you are using and I pray that you are not venting the gas.

Ever heard of Boyles Law?

I am under constant pressure to explain why the difference in temperatures is more important than the absolute temperature of one or the other ... Charles.

In that case, a class in thermodynamics might help.

ξ

I think that's chemistry, not thermodynamics.

ξ

PV=nRT under constant pressure ... ideally ... Delta (T/V) = increase in temp ... increase in volume ... Otto cycle bad ... turbine good (or quasi-turbine) ... read post 15 again. I only know physics ...

The question is a bit bizarre ... Increasing cfms requires reducing the resistance downstream at a given pressure head ... why would you want to do that?

Have you considered a Stirling engine?

Yes I haveconsidered a Stirling engine but have not been able to locate one for sale. Do you know of one for sale? This piston engine will be more efficient. I was

concerned

about condensing and cooling down steream, but feel better about it now. Thanks, Nick

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The pressure in the cilinder should depend on the pressure that the gas is expanded to. Inlet pressure should be equal to the outlet pressure plus the change in pressure that is required to run you engine. Keep in mind that if the pressure is too great you wil blow a gasket or othervise damage the engine. The greater the pressure differential between inlet and outlet the more work will me generated by the same engine. Force being the pressure times the cilinder area. Again that is limited by the strength of the engine components and the drive train. If the design compression ratio is 10 you can safely have an inlet pressure of 147 psig. If it is more, then proportinally more, if less, then less in proportion. An other consideration is the cooling that takes place as the gas expands. The greater the expansion ratio the more the cooling. How do you keep the temperature from shrinking the pistons and rings to the point that much of the freon bloes by the piston?

I expect the gas to expand in the heat exchanger. When the gas leaves the heat exchanger it will be at my working temperature which will remain quite constant therefore there will be very little shrinking or expansion in the cylinder. Thanks for your help, Nick