How to size motor for compressor

  • Thread starter Thread starter martian212
  • Start date Start date
  • Tags Tags
    Compressor Motor
Click For Summary

Discussion Overview

The discussion centers around the design and sizing of a motor for a low flow single piston reciprocating compressor. Participants explore calculations related to torque requirements, compression capabilities, and the implications of specific design choices such as piston stroke and motor type.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks assistance in calculating the required torque for a compressor designed to operate at 20 psig with a flow rate of 4 LPM.
  • Another participant questions the feasibility of achieving significant compression with a piston stroke of only 0.100 inches, suggesting that the dimensions may need to be reconsidered.
  • Some participants propose using the energy method to estimate power requirements, indicating a relationship between power, density, flow rate, and head.
  • Concerns are raised about the compression ratio and the effectiveness of the design given the small stroke length, with suggestions to consider the use of check valves.
  • A participant mentions the intention to use a flapper check valve and seeks further guidance on calculating the required torque.
  • Another participant highlights the importance of understanding the total compressed volume and asks about the proximity of the piston to the top of the compression chamber.

Areas of Agreement / Disagreement

Participants express differing views on the adequacy of the compressor's design parameters, particularly regarding the stroke length and its impact on compression capability. There is no consensus on the feasibility of achieving the desired performance with the specified dimensions.

Contextual Notes

Participants note potential limitations in the design, including the small stroke length and its implications for compression efficiency. There are also unresolved questions regarding the specific calculations needed for torque and the overall design viability.

Who May Find This Useful

Individuals interested in compressor design, motor sizing, and those working on similar engineering projects may find this discussion relevant.

martian212
Messages
5
Reaction score
0
HI - I'm looking for some help. I'm trying to design a low flow single piston reciprocating compressor. Here is what I have:

-Piston bore diameter- 1.50 in
-stroke- 0.100"
-should be able to go up to 30 psig
average pressure will be 20psig
-I am looking for the air flow to be 4.00 lpm at a back pressure of 20 psig
-I believe the rpm of the motor should be about 2700 rpm

How do I calculate what torque will be required at a back pressure of 20 psig and obtain a flow of about 4 LPM.

I would really appreciate the help.

Thanks!
 
Engineering news on Phys.org
One more thing-I plan to use a brushless dc motor for this design
 
can't anyone please help with this? Thanks
 
You are not going to get much compression with a piston that has a stroke of only 0.100". Please check all dimensions of your compressor.
 
All the dimensions are correct. The stroke is so small because I do not need that much flow.
 
You can work that out roughly by energy method. Power = ρgQH = Tω.
 
You are asking for 30 psig. This is 15 psia to 45 psia, a 3:1 compression. I doubt that you can get this with a 0.100" stroke, when you consider the whole volume that is getting compressed. Are you planning to use 1-way check valves, or is the compressor an overhead valve machine?
 
True, I may have to up-stroke. I am planinning to use a flapper which is similar to a one way check valve. Any thoughts on what my required torque would be? Or how to calculate it?
 
Don't you have TWO flapper check valves, one on the input and the other on the output? The total compression stroke you have is 0.177 cubic inches with a 0.1" stroke. The TOTAL compressed volume between flapper chsck valves has to be about 33% (or less)of 0.177 cubic inches. How close (in mils) will the piston be to the top of the compression chamber at the top of the stroke? 10 mils? How sacred is your 1.5" piston diameter?
 

Similar threads

  • · Replies 33 ·
2
Replies
33
Views
4K
Replies
1
Views
1K
  • · Replies 20 ·
Replies
20
Views
5K
Replies
23
Views
3K
Replies
58
Views
9K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 3 ·
Replies
3
Views
8K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 11 ·
Replies
11
Views
3K