I need 2 gases with diff. pressures to enter into a chamber, combine and come out with a required pressure (that required pressure will be set by me). The input pressures may not be always greater than the required output pressure.
If the input pressure is lower than the input pressure you will have to consider having an compressor in your system in order to compress the gas. I don't even know if this would be 100 % possible.
What are the pressures that are admited to the chamber? very high or very low?
If the input pressure is lower than the input pressure you will have to consider having an compressor in your system in order to compress the gas. I don't even know if this would be 100 % possible.
What are the pressures that are admited to the chamber? very high or very low?
Your question is very abstract and devoid of important details. Pressure ranges are not given and type of the gas is also not given. Moreover it appears to be a special process requirement and if it is not application or process specific, a single mechanical device may not be available readily in the market.
One way to achieve this is to use a differential pressure regulator to reduce the higher of the two input pressures to equal to the lower input pressures. Mix these two gasses in the required ratio using two flow regulators or a mixer depending on the quality of the mixture desired. If the required output pressure is about two to three times higher than the mixture, you may use a booster. Otherwise you may need to use a compressor (provided it is safe enough to compress the mixture without igniting it). Use a Pressure regulator at the output to regulate the mixture to the required output pressure.
You should also provide some info on the temperature and the nature of gases. For instance if you are mixing two inert gases you have more options than the case of an explosive mixture.
Assuming you have the two gases from high pressure bottles (let's say 200 atm) you can use pressure regulators for both (consult gas providers like LINDE, Air liquide, Praxair, etc.). These will provide "low pressure" and you will be able to adjust them and therefore to change proportions in the mixture. The output pressure for the mixture will be a result of these two input ones, the output pressure being always lower than the input ones. By this method you can obtain stable pressures from 0 to aprox. 20 bar. (this is what a gas welder essentially does)
But consider that once you regulate the reducers, if temperature changes the output pressure will also change.
Please look into some diving regulators, two of these combined can provide output equal to the surrounding pressure and can take two different high-pressure inputs. scubapro.com or cressi.com?
You have to solve first the thermodynamic problem of mixing two real gases and find out the characteristics of the resulting mixture, which will be your output.
It will be of interest to you if you read the concept of mixing chamber contained in the following reference
Steady- and Cryptosteady-flow underwater thrust augmentatio, by J.V.foa and Th. Costopoulos, TR-UTA-762, George Washington University, School of Engineering and Applied Science, 1976
Sujith, problem you have formulated splits into several mechanical solutions depending on the conteplated flow rates, the supply pressures, the difference between the supply pressures, the required accuracy and control, and overall cost of the projected device. First issue is of course the requirement that the pressure of the gas mixture exceeds the pressure aft the exit nozzle, as was already suggested to you, above. My take on the problem is that you start solving this design problem by employing a 'rocking horse', or a ballancing (oscilating) regulator and set it the way that bouncing between the two gas supply channels automatically sets the portionning of gases supplied via ducts in the bottom, or a horseshoe stem of the 'horse'. Downflow the 'rocking horse' you have a mixing chamber ('the packing chamber' to be technically correct), where the vortices, oscillations and/or turbulence would gladly take care of the gas mixing for you. It may very well not be the target solution you are after, I suspect, but would let you organize the control of the 'left' and 'right' reach of the ballancer, say, by putting limiting screws and get all the physics and timing right. Once this is done you would probably have to jump to using fast response solenoid valves, working on pulsation to get the precision portioning tip top, and some electronic sensors to get it even more precise. Electronic solution is ultimately a bit cheaper, but yoy would have to get the precie feeling for the design problem before you jump to builiding all the circuitry.
Gas mixers being able to handle gasses in the way you described it are commercially available. You might have a look at the following website: http://www.wittgas.com/EN/gas_mixers.html
Best regards
Susanne
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