IOSR Journal of Engineering (IOSRJEN) e-ISSN: 2250-3021, p-ISSN: 2278-8719 Vol. 3, Issue 7 (July. 2013), ||V1 || PP 09-15 www.iosrjen.org 9 | P a g e Control Of Heat Exchanger Using Internal Model Controller K.Rajalakshmi $1 , Ms.V.Mangaiyarkarasi #2 $ PG student, Department of C&I, Valliammai Engineering College, Kancheepuram District, Tamilnadu, India # Asst.Professor,Department of EIE, Valliammai Engineering College, Kancheepuram District, Tamilnadu, India Abstract: - Heat exchanger is a device that exchange the heat between two fluids of different temperatures that are separated by a solid wall. The temperature gradient or the differences in temperature facilitate this transfer of heat. In General, temperature control system has the characteristics of non-linearity, large inertia and time variability. It is difficult to overcome the effects of these factors and get the satisfactory results by using the normal PID controller. Therefore, the PI, FOPID, FUZZY and IMC are the controllers implemented in this paper to control the output temperature of the heat exchanger system. The PI, FOPID, FUZZY and IMC are the controllers are compared, based on their overshoot and settling time the conclusions are given using simulation results. As a future work FOPID controller tuned using genetic algorithm will be implemented in this paper later for better effective temperature control over other controllers. Keywords: - Internal model based controller, PID controller, Fuzzy controller and Shell and tube heat exchanger system. I. INTRODUCTION In practice, all chemical processes involve production or absorption of energy in the form of heat. Heat exchanger is commonly used in chemical processes to transfer heat from a hot fluid through a solid wall to a cooler fluid. There are different types of heat exchanger used in the industry but most of the industry use shell and tube type heat exchanger system. Shell and tube heat exchangers are probably the most common type of heat exchangers applicable for a wide range of operating temperatures and pressures. They have larger ratios of heat transfer surface to volume than double pipe heat exchangers and they are easy to manufacture in a large variety of sizes and configurations. A shell and tube heat exchanger is an extension of the double-pipe configuration. In shell and tube heat exchanger one fluid flows through the tubes and a second fluid flows within the space between the tubes and the shell [8]. This paper reports a work that considers a shell and tube heat exchanger. The outlet temperature of the shell and tube heat exchanger system has to be kept at a desired set point according to the process requirement. Firstly a classical PI controller is implemented in a feedback control loop so as to achieve the con trol objectives. PI controller exhibits high overshoots which is undesirable. To minimize the overshoot Fuzzy logic controller and internal model based controller is implemented. Fuzzy logic controller reduces the overshoot but it leads to the steady state error in the process. The internal model based controller design has gained widespread acceptance because it has only a single tuning parameter namely the closed loop time constant Ȝ. The internal model controller reduces the overshoot and settling time. In this paper three types of controllers are designed to achieve the control objective and a comparative study between the controllers are evaluated. II. SHELL AND TUBE HEAT EXCHANGER SYSTEM A typical interacting chemical process for heating consists of a chemical reactor and a shell and tube heat exchanger system. The super-heated steam comes from the boiler and flows through the tubes. Whereas, the process fluid flows through the shells of the shell and tube heat exchanger system. Different assumptions have been considered in this paper. The first assumption is that the inflow and the outflow rate of fluid are same. The second assumption is the heat storage capacity of the insulating wall is negligible. A thermocouple is used as the sensing element which is implemented in the feedback path of the control architecture. The temperature of the outgoing fluid is measured by the thermocouple and the output of the thermocouple is sent to the transmitter unit, which eventually converts the thermocouple output to a standardized signal in the range of 4-20 mA. This output of the transmitter unit is given to the controller unit. The controller implements the control algorithm, compares the output with the set point and then gives necessary command to the final control element via the actuator unit. The actuator unit is a current to pressure converter and the final control unit is an air to open valve. The actuator unit takes the