In-situ implementation and evaluation of an online robust pump speed control strategy for avoiding low delta-T syndrome in complex chilled water systems of high-rise buildings

Dian-ce Gao, Shengwei Wang and Kui Shan

Applied Energy, 2016, vol. 171, issue C, 554 pages

Abstract: The low delta-T syndrome is one of the major faults that affect the operation and energy performance of the chilled water systems in practice, particularly for the complex chilled water systems. Low delta-T syndrome refers to the situation where the measured mean temperature difference of the overall terminal air-handling units is much lower than the expected normal value. The conventional pump speed control strategies lack the ability to handle the low delta-T syndrome. This paper presents an online robust control strategy for practical applications to avoid the low delta-T syndrome for chilled water systems including complex systems. On top of the conventional control strategies, a temperature set-point reset scheme is developed aiming at providing the reliable temperature set-point for enhancing the operation reliability of chilled water pumps. In addition, a flow-limiting control scheme is employed to perform the function of actively eliminating the deficit flow in the bypass line by a feedback mechanism. This robust pump speed control strategy has been implemented and evaluated on a real complex chilled water system in a high-rise building. The site test results show that the temperature set-point given by the proposed strategy is reliable and the system temperature difference is significantly raised by eliminating the deficit flow problem. When compared to the conventional control strategies, 78% of the total chilled water pump energy was saved in the test period. The actual pump energy saving percentage could be 39% in a year after implementing the robust control strategy in the studied system.

Keywords: Low delta-T syndrome; Chilled water system; Pump speed control; Building energy (search for similar items in EconPapers)
Date: 2016
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Citations: View citations in EconPapers (8)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:171:y:2016:i:c:p:541-554

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DOI: 10.1016/j.apenergy.2016.03.077

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