Estimating monthly/yearly energy costs

[Dacosta]

Anyone know how to estimate typical duty cycles for a typical refrigeration system to estimate the energy costs?

I’m trying to evaluate the energy savings of placing a VFD on a screw compressor. The VFD salesmen is asking what is the typical duty cycle for evaluation purposes.

Is there a simple way to estimate or long way to calculate how much time a typical screw compressors runs at

100%, 90%, 80%..... ect?

Thanks

Dan Acosta

[Segei]

Anyone know how to estimate typical duty cycles for a typical refrigeration system to estimate the energy costs?

I’m trying to evaluate the energy savings of placing a VFD on a screw compressor. The VFD salesmen is asking what is the typical duty cycle for evaluation purposes.

Is there a simple way to estimate or long way to calculate how much time a typical screw compressors runs at

100%, 90%, 80%..... ect?

Thanks

Dan Acosta

It is not easy to estimate real energy savings from VFD. First you need real operating conditions. Many salesmen will give you estimation for 180 psig head pressure. Do they suggest to run a plant at 180 psig all year around? Rough estimation can be done by choosing average load and average head pressure. For example. Minimum load setting for the compressor is 40%. Average load will be (100+40)/2= 70%.