The Investigation of Methodologies for Optimal Control of Chillers and Cooling Towers System
Date Issued
2007
Date
2007
Author(s)
Chang, Chun-Chuan
DOI
zh-TW
Abstract
This thesis presents two methodologies for determining the optimal control settings of condenser water system of chiller water plant. One is applied to the system operated with single chiller and cooling tower, and the other is utilized to the system with multiple chillers and cooling towers. By using these methodologies, the power consumption of the system can be minimized.
In this research, a mathematical model was developed to predict the power requirement of a chiller under the cooling capacity varied through time, and the water temperature at the time entering condenser and leaving evaporator. Another mathematical model was developed to predict the power requirement of a cooling tower with various ambient conditions, tower air flow rates, tower inlet and outlet water temperatures. By integrating those models, this thesis develop an algorithm for investigating optimal control settings of the system consisted of single chiller and cooling tower, those settings changes through time in respond to uncontrolled variables such as the ambient conditions and the system cooling loads.
In a multiple-chiller system, an optimization methodology was developed by integrating the Penalty Function Method (PFM) into the algorithm developed before, where PFM was applied to optimize chiller load distribution. Besides, a strategy was added to save energy. The strategy was utilized to shut down the chillers which operate inefficiently in order to let the rest of the on-line chillers to operate more efficiently and to reduce the energy consumption as well.
Results of this optimization methodology are compared with the methodology integrated with Equal Load Distribution Method (ELDM). The results show that the PFM can save 1.7~8.8% total power compared with ELDM while the system load is 60~70%. When the system cooling load is 30%, PFM saved 27.86% total power consumption of multiple chillers and cooling towers in the system.
Subjects
冰水主機
冷卻水塔
最佳化
懲罰函數法
Chiller
Cooling tower
Optimal
Penalty function method
SDGs
Type
thesis
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