VSD fans at part load

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Dear eQuest users,

I am trying to model Variable Speed Drive Fans. The EIR (Electric Input
Ratio) as a function of PLR (Part Load Ratio) can be defined as a
quadratic performance curve with the help of Row Data Points given by
the manufacturer.

The fans are designed to work at part-load of 0.75 or less because this
way they are more energy efficient, i.e. the supply electrical power
intensity kW/cfm is lower.

What would the Design kW/cfm be in this case? I am thinking of using the
power intensity that is given at 0.75 Load Ratio as in the actual system
this will be my pick conditions. But I am not feeling very confident
with that.

Should the Design cfm of the supply flow be defined or calculated by the
program? In the case of it being defined what would be the input value:
the air flow of the 0.75 part load (at pick conditions) or the 1.00 full
load ratio that is never applied.

Any help will be appreciated. Thanks in advance,

Christina Galyfianaki

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Joined: 2011-09-30
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