Solar Air Compressor intake problem

[RKD89]

Hi Guys
I m thinking of making a Solar air compressor
ie
heating air in a closed vessel ( constant volume heat addition) using parabolic reflectors etc till reaches an optimum pressure
At this point a check value opens, and the the pressurised air is made to pass through a heat exchanger ( the air cools down but pressure remains the same (neglecting losses)
connecting a series of such arrangements can give decent compressed air


However my main problem is how the suction of air into the first/initial vessel itself

When the pressure in the first vessel reaches an optimum level, the check valve will open releasing the 'pressured hot" air into the heat exchanger,
THE link that I followed says that a partial vacuum will be created inside the vessel which will be enough to suck fresh atmospheric air( via a non return valve) into the vessel

Is it really going to work??......will the partial vacuum be enough or do I need an external source for intake?
Will I need a any specific 'Delayed' check valve to create the vacuum?

Also does the overall idea seem to work??

 

[Jobrag]

Sorry this can't work, what you are doing is putting energy into the air by heating it and then taking it out again in the heat exchanger, result the pressure will fall again, You don't say what you want to use the air for, or the type of volumes you need, but solar cells and an electric compressor are a better option.

 

[Topher925]

Sorry this can't work, what you are doing is putting energy into the air by heating it and then taking it out again in the heat exchanger, result the pressure will fall again, You don't say what you want to use the air for, or the type of volumes you need, but solar cells and an electric compressor are a better option.

Yes, most definitely.

Although it will be more efficient to have a solar concentrator drive a Stirling engine that is directly connected to your compressor rather than using solar panels and an electric motor. What pressure and flow rates are you trying to achieve?

 

[Q_Goest]

I disagree with the above. Here's what I'd suggest as the apparatus we'll use to explain whether or not this would work.
- A compression chamber with a check valve flowing into the chamber and a check valve flowing out.
- A heat source capable of heating the compression chamber to above ambient.
- A cooling source capable of reducing compression chamber temperature to ambient.
- A storage volume on the outlet of the compression chamber which also acts as a heat exchanger to reduce air temperature to ambient.

That's all we need, but we could also add additional compression chambers. To simplify the device, let's just ask the question of whether or not this device can compress air into the storage chamber.

Let's assume the following steps:
1. Air at ambient temperature in compression chamber and storage volume.
2. Air in compression chamber is heated, forcing air to discharge into storage volume.
3. Air in storage volume is cooled to ambient but since additional mass has been added, pressure must have risen when temperature = ambient. Note that the cooling of the air can't commence until the air has left the compression chamber and entered the storage volume.
4. Air in compression chamber is cooled, reducing pressure and admitting air into chamber.

As this cycles, pressure in the storage chamber gradually rises until it matches the pressure of the air in the compression chamber at the end of step 2, at which point, air can't be forced out through the check valve and into the storage volume.

I don't see a fundamental problem with the basic concept. It should work, and one should be able to add additional stages to this device.

This system reminds me a bit of a device called the Trifecta by Chart Industries that pressurizes liquid nitrogen by heating it, then refilling the container from a separate source and cycling between these two very low (cryogenic) temperatures. I wouldn't be surprised if a similar device at ambient temperature was already designed and patented.

 

[Topher925]

Woops, I didn't quite understand the apparatus, I stand corrected this will work.

This is basically just a spin off of the well known Stirling compressor but without water and using solar power as a heat source.

http://renewableenergy.wikia.com/wiki/Hydrostatic_Stirling_cycle_air_compressor

 

[Jobrag]

Yes O Goest that would work but it's not what was described originally,