The piping distribution system consisted of a primary loop to a series of AHUs. The West Wing addition included a separate chiller plant with two (2) double effect 250-ton absorption chillers with a similar primary loop piping distribution system throughout and two (2) outdoor counter-flow cooling towers. As part of the design, the two (2) plants were interconnected through cross-over piping between their primary CHWS and CHWR mains, with underground piping run between the two (2) wings. Though not anticipated, when cross connected, the systems were not able to satisfy peak load conditions at the Medical Center.
As a result, during the expansion and renovation project, K&L Group was selected to perform a feasibility study and system design to improve the efficiency and redundancy of the chiller plant and CHW distribution system. Consideration was given to the upsizing of various chillers, the design of a primary-secondary pumping system, replacement of pumps, controls and piping, cooling towers and the elimination of CFC refrigerants. A life cycle analysis was performed using all available input including operating, maintenance, and energy costs, installed costs and life expectancies for different equipment. The analysis gave consideration to a forthcoming East Wing building addition along with various phasing issues for construction and start-up. The study and design resulted in the determination that the two (2) 235-ton CFC chillers should be replaced with new 375-ton electric centrifugal chillers, running R-134A (HFC) refrigerant. A new primary-secondary piping loop was also constructed in order to achieve the full benefit of diversity and load sharing amongst the Medical Center’s two (2) wings, as well as to support the forthcoming East Wing building addition. The system consisted of new pumps, controls, chiller plant piping, cooling towers (4 cells with variable speed drives) and underground secondary loop piping.
Project completed by K&L Group, A Division of MG Engineering