Sizing a reciprocating compressor

[mdossaji]

I am working on developing a 2-stage horizontally opposed reciprocating compressor operating at 1800 RPM at 2.1 in stroke. The standard rule is to produce equal compression ratio between the two cycles but I know that is not possible especially when adding suction/discharge pressure loss and clearance volumes. Does anyone have a set of calculations or formulaes that would help me size the Low pressure and high pressure cylinders by entering the required SCFM, suction pressure (should pressure loss from inlet filter and valve opening be included?), suction temperature, and discharge pressure (10 bar).
And what is the ideal way to calculate the power needed to run such a compressor. Does work done by compression a good way to calculate the HP or should I use torque?

 

[bcs5274]

hard to size anything without parameters and compressor oem's have sizing programs on their websites

 

[Montemayor]

You obviously are not an experienced compressor designer/manufacturer. You should already have successfully completed several thermodynamic university courses in mechanical engineering to fully understand what is confronting you. If you did, this would help you understand how and why there is an attempt to have equal compression ratios in each stage of a multistage machine. You would also understand how/why there are limitations.

There are no “set of calculations or formulaes that would help” you size the machine. There is only basic thermodynamics and engineering. Existing manufacturers have already gone through this preliminary learning phase and have developed empirical know-how information and relations that enable them to build their machines. I’m afraid you would have to go through the same learning curves.

Unless you have a lot of time and money on your hands, I would not dedicate an effort in this endeavor since there are existing manufacturers who do this. There are also others who have given up the ghost and closed up their shops after many years. The profit incentives are not really there.

This advice is not meant to throw cold water on your aspirations, but rather to let you know that you are working on an effort that is not that simple to conquer competitively. It is far easier to buy the machine or the technology.

 

[Vegaskid]

You can get a copy of the Aerial sizing program but I don't think it will help you much if you've never sized anything.

If this is for your work, ask an experience Rotating Eng or just fill out a data sheet and send it in for a quote.

 

[ARenko]

I agree with Montemayor. That said, Ariel publishes their calculation methods...

http://www.arielcorp.com/application_manual/arieldb.htm

 

[gurmeet2003]

Sound engineering advice. I am an ex-Ariel engineer who spent a life time on these and other compressor issues.

Gurmeet

Gurmeet
Time is an illusion. Now is the only thing there is.

 

[koba78]

allowing 10 psi pressure drop between stages with equal compression ration
per stage, there is formula obtained as flows

Pd1/Ps1 = Pd2/(Pd1 - 10)

where
Pd1 = first stage discharge pressure (psia)
Ps1 = first stage suction pressure
Pd2 = second stage discharge pressure

Thanks.

 

[dcasto]

wow, torque or HP, are you serious? Hire a professional and learn from him.

sorry for being blunt.