Printable View
Hi, I am monitoring a couple low and medium temp hill phoenix racks. Both have Bitzer screw compressors with two unloaders on each compressor staging capacity at 50%, 75%, and 100%. I have had great success in removing unloaders from capacity control on Carlyle screws because of their inefficiencies. I don't know much about the Bitzers yet and was wondering if anybody had any experience or data on Bitzer screw unloaders and efficiencies?
Bitzer HSN5343-25 Low temp
Bitzer HSK5343-30 Med temp
generally the unloaders open a bypass port on the screw length. Disconnect power to each solenoid coil will keep compressor fully loaded. Ramp speed up and down with a VSD would be more efficient, minimum hertz for oil flow is around 30 Hertz
Quoting Magoo. Unloaders simply creates by-pass which means you spend power in compressing and then you by-pass what you compressed ... very poor efficiency. VSD is the way.
Hi Joel404a
Do you not need capacity control for you application? It would be interesting to see the difference between running a lower SST due to less staging VS the Parasitic losses of utilizing the Unloaders.