Automatic Control System for Shell and Coil Heat Exchanger with Variable Heat Exchange Surface Area

Abstract

The work is devoted to the temperature control system at the outlet of a shell and coil heat exchanger with a variable heat exchange area, subjected to a change in the surface area by changing the level of the heated coolant in the heat exchanger. The aim of the study is to develop a model for the process of changing the heat exchange surface area and a temperature control system at the outlet of such a heat exchanger when the level of the liquid changes. The set goal is achieved by solving the following problems: development of discretization schemes for a system of differential equations describing the dynamics of the heat exchanger, development of an automatic control system for the temperature at the heat exchanger outlet by changing the heat exchange surface area of the heat exchanger and assessing the possibility of compensating disturbances. The most significant results are: discretization schemes for equations of dynamics of a heat exchanger with a variable heat exchange surface area, the use of which makes it possible to improve the accuracy of modeling and in the substantiation of the structure and choice of parameters of the controller. The paper presents two discretization schemes for differential equations of the dynamics of heat exchanger: a scheme using the method of lines and the method of running counting. It has been established that when using a scheme using two pumps to level control, the dynamics of the object depends on the sign of the derivative of the control signal.

Keywords

• heat exchanger
• variable heat transfer surface
• control system
• mathematic model
• heat pump.