Study On Dynamic Characteristics Of Tubular Heat Exchanger

Tubular heat exchanger is commonly used in industrial waste heat recovery, the conditions of the heat exchanger are variable and unstable while it is in practical operation. In order to make the heat exchanger work under high efficiency, the dynamic characteristics of tubular heat exchanger need to be discussed. This will be three common tubular heat exchanger as the main object, a modular modeling approach to study the lumped parameter modeling and design of MATLAB/Simulink common procedures. Around this objective, the paper carried out the following work:1) To single cross-flow heat exchange based modules, a dynamic control equation is established. For the typical working conditions, put forward a single dynamic modeling of heat exchange tubes to be piecewise. Not more than one meter length of each section. Heating medium temperature within each section can be considered by the linear distribution, heat uniformity.2) Fluent, a common CFD software, is used to obtain the heat exchange’s static operating point, combining with theoretical calculation proved results reliable. Using MATLAB/Simulink software to build a model of dynamic control equation, the perturbation results reliability verified by Fluent software.3) To the MATLAB/Simulink solving model of single cross-flow heat tubes based modules, to the way of the equivalent heat exchange tube, through the different serial and parallel way, set up dynamic simulation models of groups of two-stroke against the cross-flow heat exchanger、one group of four-stroke against the cross-flow heat exchanger、single four-stroke cross-flow heat exchangers of commonly used in industries. Using Fluent software to obtain the static operating point and verify the results. Through perturbation experiments, the dynamic parameters and the transfer function were obtained.4) Comparison of dynamic characteristics parameters of three types of heat exchanger, to analyze the merits of its dynamic characteristics. To increase the air outlet temperature from the value of the disturbance degree subject, on the design of heat exchangers made the following recommendations:①To increase the degree of flow disturbance from the value required to increase the flow, that is, to increase the number of each tube for air, to increase the number of restraint windward for flue gas;②To increase the impact of its inlet temperature disturbance, need to increase the flow, that is, increase of tube length or increase the number of strokes.