Control of a cooling tower: implementation using fuzzy logic controller

• Main Author: Tonic, Jesus Dante B.
• Format: text
• Language: English
• Published: Animo Repository 1997
• Subjects: Electric controllers; Cooling towers; Water heaters; Fuzzy sets; Temperature control; Fuzzy systems; Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/1879
• Institution: De La Salle University

Modern control systems offer the advantages of ease of operation, accurate results, remote control, and high performance. The never ending quest for solutions to control problems has prompted scientists to come up with more advanced techniques. With the advent of fuzzy logic, appliance manufacturers have shifted their approach on controllers. This thesis employs fuzzy logic controller in heating the liquid (water) entering a cooling tower. A water supply is tapped from the faucet with nominal temperature of 28 to 30 degrees Celsius and is pumped by an ordinary water pump. The output of the pump branches in two ways one for the bypass that has a manual gate valve and the other, for the cooling tower. Before the pumped water reaches the cooling tower, it passes through another gate valve, the flow rate is sensed by a flow sensor and the water goes to the heater system. The water temperature entering the cooling tower may be varied according to the user's needs. A control knob can be found on the control board used to select the desired water temperature range. The three input variables used in this study are the following: 1) THi - for high temperature cut-off, 2) TSet - for the desired temperature setting, and 3) TOut - for the water outlet temperature. On the other hand, five types of membership functions and 11 rules are used in this study (Refer to Section 5.10 for the complete rule set).The experimental results are very promising. No overshoots and oscillations occurred in all of the experiments. The water temperature entering the cooling tower becomes stable after 75 to 120 seconds when changed from one setting to another. This study is concentrated on the control of the water temperature entering the cooling tower, implemented using a fuzzy logic water heater controller. Several parameters are monitored and stored using data acquisition system. Parameters include the water flowrate, and the entering and leaving water temperatures.