The Research Methods And Theory Of Improvement Of Heat Exchanger Network Optimization And Optimal Control

Heat exchanger network is an important system for energy recovery, sensitivity analysis and flexibility analysis plays a vital role in the design, improved optimization and optimal control of heat exchanger network. The sensitivity analysis and flexibility analysis of heat exchanger network were of in-depth study in this paper. In order to resolve the problem of the heat exchanger network at a minimum or the minimum investment for transformation, and the optimization problems on the optimal control performance of heat exchanger network, the theoretical methods and mathematical models of the sensitivity analysis and flexibility analysis were established.The mathematical models of sensitivity coefficient, sensitivity analysis and flexibility analysis were established, which based on the definition of sensitivity coefficients, sensitivity and flexibility index. The models could determine the decision variables, state variables and parameters, automatically, and the solution method could be given. Through the combination of the established model with heat exchanger networks process simulation, the heat exchanger network could be optimized. The raw data was preliminary calculation by the mathematical model, and then process simulation was performed. If you do not meet the design requirements, you can return iterative calculation, after then process simulation, repeat the process until satisfied. This method can avoid the difficulty in calculating the complexity of nonlinear programming problems, which can greatly reduce the amount of calculation and improve the accuracy.The Inter Visual Fortran language was used to prepare the computer program for the established mathematical model and methods, the changes in the network could be seen from the program’s output, and the method of optimizing the network could be known in the meantime. This could be assessed with engineering example and the results obtained in this work were compared with the sensitivity analysis and the classical flexibility analysis. It indicates that the annual integrated cost is $30479, which is lower than $34376 come from other literature. In addition, the method used in this study was characterized by simple inputting, saving calculation time and reducing computational error, which confirmed it was correctness and unique.The programming was embedded in the software of "the heat exchanger network optimization and energy saving systems", constituting sensitivity analysis and flexibility analysis module, which can improve the software features and easy to use, make the software more powerful.