Commissioning an Existing Heat Recovery Chiller System at a Large District Plant
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© 2018 ASHRAE A heat recovery chiller provides heating hot water to buildings by using recoveredheat from the chiller, whichis efficient and cost-effective. However, not every central plant is an appropriate application for heat recovery chillers because coincident heating hot-water and chilled-water loads are required. Most previous studies on applications of heat recovery chillers have focused on techniques for optimal design of a utility plant with heat recovery chillers. There are very few guidelines for operators on how to run a heat recovery chiller system efficiently at different operating conditions. Factors include electricity demand charges and rate structure, heating hot-water supply temperature, heating hot-water loop delta-T degeneration, chilled-water loop delta-T degeneration, and the performance of other variable-speed drive chillers in the plant, which all affect operational efficiency. This paper presents several commissioning measures for a heat recovery chiller application at a large district plant in central Texas. The on-site measured data from the building automation system (BAS) is used to develop a regression model to evaluate the savings potential for each measure. The current operating strategy saves $270,375/year compared to a baseline chiller without heat recovery, but the proposed control strategies would improve the savings to $389,182/year at current utility prices, or 43.9% more savings than the current control strategy. Although these savings are based on a case-study project, the methodology and control strategies can be applied to optimize other heat recovery chiller applications.
author list (cited authors)
Wang, L., Sakurai, Y., Bowman, S. J., Claridge, D. E., & ASHRAE, ..