| Summary: | 碩士 === 國立臺北科技大學 === 自動化科技研究所 === 98 === The temperature of refrigerant will increase or decrease depends on the unloading or loading of chiller. Then, the temperature of refrigerant will affect the capacity of chiller. This thesis studies the capacity control of screw type chiller which is widely used in the field of central air conditioning.
In general, the outlet or the inlet chilled water temperatures are adopted in the chiller capacity control. For the outlet temperature control, the control strategy is easily applied and the response is controlled to be fast based on the analysis of control block diagram. However, the inlet temperature control should be applied for the purpose of comfortable environment temperature and energy-saving issues.
There are three kinds of capacity control strategies, including steps capacity control system, continuous (stepless) capacity control system and the inverter control system. Firstly, the advantages and drawbacks of above capacity control systems are analyzed in detail. Then, we describe the problems of steps capacity control and continuous capacity control to further propose the improved strategies. Furthermore, the fuzzy control technology is taking into account both the temperature difference and the rate of temperature change under the condition of unknown system modeling. Finally, the experimental results of a case reveal that the controlled temperature is more stable than tradition continuous capacity control in setting temperature.
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