With a substantial amount of today's water-cooled chillers lacking the energy efficiency of some newer systems, retrofitting can help meet existing efficiency levels as well as comply with today’s refrigerant requirements. 

In an interview with MEP Middle East, Dan Mizesko, managing partner, US Chillers, said: "Retrofitting allows people to modernise their chillers without any loss of capacity and it helps make the existing chillers much more energy efficient while allowing them to move away from currently phased out refrigerants."

Mizesko said that multiple oil-less magnetic bearing compressor can replace the single or dual centrifugal compressors.

He added: "No centrifugal chiller offered today, even with a variable frequency drive (VFD) installed on the compressor, can operate as efficiently as an oil-less magnetic bearing centrifugal chiller. Magnetic bearings offer superior reliability and performance for chiller operation. 

"A retrofit of an existing large tonnage single compressor chiller to multiple oil-less magnetic bearing compressors will operate even more efficiently than the current single oil-less magnetic chillers offered today. I’m recommending installing multiple smaller compressors which allow substantial savings due to part load staging of the compressors as well as larger heat exchanger on the condenser when operating under lighter loads.

"This offers large opportunities for additional savings beyond the efficiencies of a single compressor oil-less magnetic chiller. Chillers using the variable speed oil-free multiple centrifugal compressors with magnetic bearings offer a rated efficiency in the range of 0.33 to 0.37 kW/tonne integrated part load value (IPLV)."

To read Mizesko's entire views, check out #1303 of MEP Middle East, which will be out on the first week of March.