Where i have applied VFD is on one compressor, centraliced DX systems. On such systems the VFD gives the posibility of significant energy savings. On a system for frozen cases i found i could run at an evaporator temperature of -31,5 oC instead of the suplier specified -35 oC. That was wery simple to adjust seamlessly with a VFD. As Iceman says, it all has to do with capacity regulation. It is there the possible energy savings is.
On large systems with a compressor rack, with maybe different sizes of comps and/or comps with capacity steps on themselves, you normaly have the posibility to a near seamless capacity regulation without VFD. And therefor there is not anything to save.
The same applies to one comp-one evaporator systems, at least if the evaporator have a large capacity compared to the compressor. more on http://www.gozuk.com/variable-frequency-drives.html
On large systems with a compressor rack, with maybe different sizes of comps and/or comps with capacity steps on themselves, you normaly have the posibility to a near seamless capacity regulation without VFD. And therefor there is not anything to save.
The same applies to one comp-one evaporator systems, at least if the evaporator have a large capacity compared to the compressor. more on http://www.gozuk.com/variable-frequency-drives.html
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