Condensers heat reject capacity regulation

[Sandro Baptista]

Hi Guys,

I'd like to hear from you guys how do you manage the heat reject capacity when you have several parallel compressors working on the same plant.

I think the best is whenever is possible all of them remaining working with the ventilation at same speed with a frequency converter (from reduced rpm until the 100% rpm) as the mechanical power consumption depends on N^3 (rpm^3).
The same reasoning applies to the Dahlander motors insteaad of the inverters.

Thanks

[Sandro Baptista]

Any comments?

[Sandro Baptista]

sTILL Any comments?

[chemi-cool]

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[Segei]

I missed this post. Did you mentioned about air condensers or evaporative condensers? This is right for air condensers.

[Sandro Baptista]

Hi Guys,

I'd like to hear from you guys how do you manage the heat reject capacity when you have several parallel compressors working on the same plant.

I think the best is whenever is possible all of them remaining working with the ventilation at same speed with a frequency converter (from reduced rpm until the 100% rpm) as the mechanical power consumption depends on N^3 (rpm^3).
The same reasoning applies to the Dahlander motors insteaad of the inverters.

Thanks

Sorry, I meant ...several condensers working in parallel.

I was thinking about evaporative condenser but I think the same principle (ventilation operating scheme) can be applied to air condensers.

[Sandro Baptista]

to my opinion, this is the best solution.
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Sorry Chemi, I can't see the relevance with my first post.

[Segei]

Reducing fan speed from 100% to 90% saves 27% of fan energy. From 50% to 40%, he same 10% speed reduction, save just 6% of fan energy. Sometimes it is more efficient to switch off water pumps.

[Sandro Baptista]

I think is better from efficient point of view switch off the fans. Also turning on and off the water pumps could lead for the formation of scale on the coil.

[Segei]

It is up to you. However, to run pumps without fans is almost useless. In North America, during cold weather many refrigeration plants cycle water pumps, because they don't have a choice. During summer operation they run pumps first. Majority of them don't have issue with the scale. To get scale you need thousands cycles of wet and dry. I know one plant that cycle pumps all year around. Yes, they have scale.