Series counterflow chiller arrangement benefits

Configuring water-cooled chiller plants in a series counterflow (SCF) arrangement splits the lift between two machines to enhance the operating efficiency of the plant.

By Cory Duggin, PE, LEED AP BD+C, BEMP; TLC Engineering for Architecture, Brentwood, Tenn. October 8, 2020

Water-cooled chiller plants are traditionally designed with the evaporators and condensers piped in parallel, which makes the compressor in each machine have to do the entire cooling delta T and lift. Lift is the difference between leaving evaporator pressure and leaving condenser pressure.  This is often approximated by the leaving temperatures.

Figure 2: Annual chiller efficiency map of a single parallel chiller. Courtesy: TLC Engineering for Architecture[/caption]

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Author Bio: Cory Duggin is the energy modeling wizard at TLC Engineering for Architecture, providing building-performance simulation efforts and high-performance design solutions. He is a member of the Consulting-Specifying Engineer editorial advisory board.