Compressing CO2 - Can Air Compressor Work?

[MSOE1]

Hi,

I am doing a design project designing a LCO2 laundering system to operate on the moon. I was looking to get some insight into how you compress CO2. Can a standard air compressor with a storage vessel that can contain sufficient pressure work to compress CO2?

Thanks

 

[Drakkith]

Remember that CO2 won't turn into a liquid until a certain pressure/temperature is reached, so make sure your system will work with CO2.

 

[MSOE1]

Correct, that is part of the design. We allow the CO2 to move in the system as a gas, then compress it enough to have a half full, horizontal axis washing machine.

The system is being designed for the moon so the equivalent system mass (ESM) has to be as low as possible. Meaning that the energy use, overall mass, volume, weight, crew member time, etc have to be minimized. So by design the CO2 would be moved by a pressure differential.

The only problem that i am having is that I don't believe a standard air compressor will work. I need to reach right around 1000 psi. I know that there are scuba diving compressors that easily can compress air to 5000 psi, but I am not sure whether or not I can use the same compressor for CO2.

 

[Q_Goest]

I design recip compression equipment that works in the range between liquid and gas. The fluid properties can vary significantly depending on whether or not the fluid is liquid, gas or supercritical, the main properties you will be concerned with are compressibility which goes into determining the volumetric displacement of each stage of compression. To design such a machine you need to have a good computerized fluids properties database that you can link to a program for determining flows and pressures. NIST has a program I would recommend called REFPROP. You can purchase it online here:
http://www.nist.gov/srd/nist23.cfm

Once you're familiar with how to use it, you'll want to create programs that calculate flow rates and pressures, power usage, valve pressure drops and valve dynamics, etc... That way you can change cylinder diameters, strokes, RPM, compression ratio, interstage cooler capacity, etc... which will give you a rough idea of what you need to do to make the machine feasible. It won't however, give you any information about materials, seal design, valve design, etc... that is critical to making a machine reliable and able to perform as well as those theromodynamic models indicate.

A better way to get the design created and a pump manufactured is to create an engineering specification for what you need and send it out for quote to a handful of manufacturers that specialize in that kind of equipment. You can do the feasibility study on your own, determining what pressures and flows you want and how large the machine might be. But once you get into the details, you'll need to find an engineering team with some experience designing the pump/compressor.

 

[pmacias]

for reaching out. This is a great question and one that has been explored by scientists and engineers for many years. The short answer is yes, a standard air compressor can technically be used to compress CO2. However, there are some important considerations to keep in mind when using an air compressor for this purpose.

Firstly, CO2 is a gas at standard temperature and pressure (STP), meaning it is in its gaseous state at room temperature and atmospheric pressure. In order to compress it, you will need to increase the pressure and/or decrease the temperature. This can be achieved by using an air compressor, but it may not be the most efficient method.

One of the main challenges with compressing CO2 is that it is a highly dense gas, meaning it takes up less space than other gases at the same pressure and temperature. This can make it difficult to compress using a standard air compressor, which is designed for less dense gases like air. Additionally, CO2 has a low boiling point, which means it can change from a gas to a liquid at relatively low pressures and temperatures. This can pose safety concerns when using an air compressor, as the liquid CO2 can cause damage to the compressor and potentially lead to leaks or explosions.

Another important consideration is the storage vessel. CO2 expands significantly when compressed, so you will need a storage vessel that can contain the increased pressure. It is important to ensure that the vessel is designed and rated for the specific pressure and temperature of the compressed CO2.

In summary, while a standard air compressor can technically be used to compress CO2, it may not be the most efficient or practical method. I would recommend consulting with a specialized engineer or scientist who has experience in handling and compressing CO2 for your specific project needs. They can provide more detailed insights and recommendations for your LCO2 laundering system. Best of luck with your project!