IMPLEMENTATION AND EXPERIMENTAL ANALYSIS OF CONVENTIONAL PID CONTROLLERS FOR EFFICIENT HEAT TREATMENT OF FRUIT JUICES IN PLATE HEAT EXCHANGER

Abstract

Steady-state and dynamic analysis of plate heat exchangers has always remained the major concern for process control in food industry. Dairy products like milk and fruit juices are treated in plate heat exchanger for pasteurization but the introduction of many inherent and uneven disturbances by the process yields both product and energy losses. The current work is aimed on the development and implementation of conventional Proportional-Integral-Derivative (PID) control algorithm in order to control the temperature of a fruit juice at the exit of a plate heat exchanger. Plate heat exchanger is used to raise the temperature of the once-through continuous flow of a fruit juice or process cold fluid up to a fixed temperature with the recycled hot water. Various types of fruit juices were processed for that purpose. The controller was tuned using the recommendations of Ziegler and Nichols (Z-N) and Cohen and Coon (C-C). The plant was logged through PID virtual controller software. The influence of load variables and set point tracking was evaluated under the Z-N and C-C controller settings and was experimentally tested for various dairy fluids. It is shown that better throughput up to 77 % recovery of product has been achieved with Z-N controller settings but at the expense of more energy consumption as compared to C-C controller settings.