Intelligent control of chiller plant for energy conservation

Pao Yue-kong Library Electronic Theses Database

Intelligent control of chiller plant for energy conservation


Author: Liu, Lizheng
Title: Intelligent control of chiller plant for energy conservation
Degree: M.Eng.
Year: 2015
Subject: Air conditioning -- Control.
Air conditioning -- Energy conservation.
Air conditioning -- Energy consumption.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: ix, 95 pages : illustrations (some color)
Language: English
InnoPac Record:
Abstract: Research shows that energy consumed by hotels has increased significantly over these years and about 75% of overall energy has been consumed for lighting, cooling and ventilation. This dissertation presents an intelligent control to improve chiller plant energy efficiency and reduce energy consumption of hotel without compromising on indoor thermal comfort.This dissertation started from a comprehensive literature review to understand the characters of the chiller plant and its critical equipment and then identify the opportunities of energy conservation.This dissertation focused on the existing chiller plant system, the improvement of the control logic and control method is therefore more practical than the replacement of equipment with higher performance. An intelligent control method has been proposed in Chapter 4. This control method is based on the analysis of the equipment on-off control and the heat transfer media control. The equipment on-off control involves operating appropriate quantity of equipment to deliver pre-set media operating parameter with minimum energy consumption, the equipment including chiller, cooling tower, pump, fan and others. This equipment optimum on-off control involves :1) mapping of equipment optimum operating condition with varying system load and other operating parameters and 2) defining of criteria for effective utilization of heat transfer surface. Heat transfer media control is to maintain the optimum media operating parameter for minimum overall power consumption by controlling the operating parameter (temperature, pressure).This has substantial effect on system energy efficiency since overall heat energy temperature elevation is substantially affected by heat transfer media flow rate. However, heat transfer media operating parameter optimum set point changes along with environmental and equipment operating conditions This proposed intelligent control has been implemented for a water cooled chiller plant used in a five-star rank hotel in Hong Kong, and the case study has been elaborated in Chapter 5. After completion of system retrofit, one-year operation data has been collected and analysed to verify the amount of energy saving.The main contribution of this dissertation is the development of an intelligent control method for a chiller plant system. Case studies showed that this control method could be used for improving the chiller plant efficiency, especially for an existing system because it does not require lot of site work.

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