Real Efficiencies of Central Plants - Actual wire-to-water efficiencies of six common central-plant types

摘要

Far too often, claims of central-plant performance are based on projections, with very little actual "pre-" or "post-" documentation. The result tends to be that actual efficiency is considerably less than what designers and operators believe it to be. This article will discuss ongoing studies of chilled-water plants in Southern California. The wire-to-water efficiency (kilowatts per ton) of six common central-plant types - air-cooled chiller, thermal-energy storage, large campus, hybrid, variable speed with screw chillers, and ultraefficient all variable speed with oil-less compressors - was measured on typical operating days throughout the year, taking into account all chillers, chilled-water distribution pumps, condenser pumps, and tower/condenser fans. The data support an obvious, but very bold, statement: If captured, the energy being wasted by our existing-building stock could meet expected near-term electrical growth in many service areas.