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Mulistage Centrifugal Compressor Effecencies

11 replies to this topic
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#1 alaasleem2026

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Posted 24 July 2024 - 09:55 AM

Peace for you
I try to estimate performance of zh1000 centrifugal compressor atlas copco
I measured temperature defrance between each stages using infrared thermometer
I ask for types of effecencies terms of my measurements and theortical work

Edited by alaasleem2026, 27 August 2024 - 05:32 PM.

#2 PingPong

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Posted 27 July 2024 - 02:46 AM

To calculate the efficiency of each stage you need the inlet temperature and pressure and outlet temperature and pressure of each stage.

To calculate the work of each stage you also need the flowrate through each stage.

Note however that infrared temperature measurements are not very accurate as they do not actually measure the gas temperature but merely the metal surface temperature on the ambient air side, which is lower than the actual gas temperature inside. Don't measure surfaces that are subject to direct solar radiation.

Moreover you would need to know the emissivity of the surface (metal or paint) which would be a guess. Make sure you set the IR thermometer to the right emissivity. Best is to apply a black marking on the surface so that you know that the emissivity of that black spot is about 0.95 . Point the IR thermometer exactly at that black spot.

Edited by PingPong, 27 July 2024 - 03:00 AM.

#3 alaasleem2026

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Posted 30 July 2024 - 07:07 AM

I modify the temperature measureing by
Modeling internal heat transfer equations
Example tout 1st stage measured value =110 C modified value =110+(Q/As*h)=125C
The problem i face
I try to calc the enthlpy of humidity air inlet and outlet each stage that give me thousands of kj/kg
How can i get approuch or any guide lines to estimate the enthalpies and efficiencies

#4 PingPong

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Posted 31 July 2024 - 06:56 AM

As I said before:

To calculate the efficiency of each stage you need the inlet temperature and pressure and outlet temperature and pressure of each stage.

Do you have those?

#5 alaasleem2026

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Posted 01 August 2024 - 12:44 PM

As I said before:

To calculate the efficiency of each stage you need the inlet temperature and pressure and outlet temperature and pressure of each stage.

Do you have those?

Peace for you Ping

i dont have sensor to measure Preasure in each stage

i try to Predict some Presure by assuming polytropic effeciency and expansion cooeffecient  after that i can Predict overoll effeciency in some advanced stages

sorry for misunderstanding

#6 astro

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Posted 02 August 2024 - 09:53 AM

I'd suggest you query AC for the machine's performance curves because without those, you'll be limited to a relatively simple analysis.

Based on this info https://www.atlascop...essor-zh-zhplus you've got a standard package machine, so often documentation for this sort of work can be hard to come by if it's not part of the standard supply.

Typically, they're also built to a cost - think of the model T Ford mantra:

https://en.wikipedia..._Model_T#Colors

"Any customer can have a car painted any color that he wants so long as it is black."

So, taking IR temperature readings is prone to error but if you don't have in-flow thermowells, then I understand you may have no other option.

#7 alaasleem2026

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Posted 03 August 2024 - 04:14 AM

Peace for you astro
I already know that munual of atlas copco but they didn't speak about preformance until we requare special order to give us preformance curve
So i try my self generating simple model to indect if there is abnormal operating condition occur or not
So i asked for some info to give more accuracy than i have example two phase analysis dry air and water vapor in each stage it about to give me some indection about how much usful power pay for

#8 Pilesar

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Posted 03 August 2024 - 07:34 AM

There are published industry standards on assessing compressed air systems.

For the most accurate assessment, the compressor manufacturer provides audit services. Contact them to find out the details of what they offer and then determine whether it would provide more value to use their expertise and tools.

#9 breizh

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Posted 04 August 2024 - 02:09 AM

Hi,

I'm not sure I understood the initial query .Why don't you review the initial report (commissioning report) and compare with actual values available?

If something is wrong with the performance of the unit you may go back to the vendor. It may also be time for overhaul of the unit.

Good luck

Breizh

#10 alaasleem2026

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Posted 08 September 2024 - 05:42 PM

Peace for you

i am in Developing stage  About Modeling how the Zh1000 Work.. and try to get Exponsion cooffection(n) for the compressor which give me the same output in achual Operation (Preasure values outlet for all stage ) when i enter the input value (Power Consumption in achual Operation )

that image for last update in the model i work on

#11 breizh

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Posted 08 September 2024 - 10:23 PM

Hi,

Consider this document to support your work

Breizh

#12 alaasleem2026

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Posted 12 September 2024 - 01:57 PM

Hi,
Consider this document to support your work
Breizh

Peace for you breizh
Thank you for tgis information
I use some of those equation to determine the n (expansion cooffecient ) value which achieve my operating condition of zh1000 depend on temperature and pressure i try to measure n equal to 1.45 for humidity air
This model also achieve the amount of water which condensed in intercooler2 lager than its in intercooler 1
But i wounder if any guide to insure power distribution to 3 stage commpressor the overoll efficiency is so small depending on power transmitted to zh1000 980 Kw but we just use 184 kw for compression process residual power for other devices in zh1000 so i think it nit effecient version of compressors in market,isit?