Comparative Study of Temperature Control in a Heat Exchanger Process

Abstract

In the present work the dynamic behavior of a plate heat exchanger (PHE)(single pass counter current consists of 24 plates) studied experimentally andtheoretically to control the system. Different control strategies; conventionalfeedback control, classical fuzzy logic control, artificial neural network (NARMAL2)control and PID fuzzy logic control were implemented to control the outletcold water temperature. A step change was carried in the hot water flow rate whichwas considered as a manipulated variable. The experimental heat transfermeasurements of the PHE showed that the overall heat transfer coefficient (U) isrelated to the hot water flow rate (mh) by a correlation having the form:U mh0.7158 =11045In this work the PHE model was found theoretically as a first order lead andsecond order overdamped lag while the experimental PHE represented dynamically(by PRC method) as a first order with negligible dead time value. A comparisonbetween the experimental and the theoretical model is carried out and goodagreement is obtained. The performance criteria used for different control modesare the integral square error (ISE) and integral time-weighted absolute error (ITAE)where the ITAE gave better performance. As well as the parameters of the stepperformance of the system such as overshoot value, settling time and rise time areused to evaluate the performance of different control strategies. The PID fuzzycontroller gave better control results of temperature rather than PI, PID andartificial neural network controller since PID fuzzy controller combines theadvantages of a fuzzy logic controller and a PID controller. MATLAB programversion 7.10 was used as a tool of simulation for all the studies mentioned in thiswork.