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Refrigeration system evaporator superheat control loop of the MATLAB simulation

1.1kW supermarket refrigerated cabinets, the use of EDM electronic expansion valve, the 7kW four-phase stepper motor driver. Ptl000 with two platinum resistance in the evaporator, respectively, import and export of attached wall to feel the evaporator inlet and outlet temperature. Evaporator for the three rows of staggered pipes, pipe length of 1410mm, when the ambient temperature of 28C pilot test device shown in Figure 4. Boot time, stability of the system, step change in the electronic expansion valve opening, its population expansion valve 250 plus electric pulse, the valve opening big 10s sampling period to capture the dynamic import and export the evaporator temperature, to obtain evaporator superheat test data signal. 4PID self-optimizing algorithm developed in MATLAB simplex method in the optimization process to achieve the controlled object PID controller parameters optimization. Select the error type of objective function, namely the time by absolute error integral. PID self-optimizing the results of K-844886, K. A 1.5701, K a 72.2222. 0 ? Mino Figure 5 PID self-optimizing the use of MATLAB simulation of Figure 5 for the use of self-optimizing PID MAT-LAB simulation results, in the evaporator exit superheat occurs when the unit step , Can electronic expansion valve in order to control the output pulse changes the effect of superheat. Figure 6 indiscriminately output pulse electronic expansion curve for the electronic expansion valve 6, the output pulse curve can be seen from the above simulation curves, in the off-line identification method used to establish the evaporator superheat and electronic expansion valve input pulse after the transfer function between using PID Optimization Algorithm for the steam in the cooling system 58 August 1999 Fluid Machinery hair superheat control loop can achieve good control quality. 5 Conclusion This paper compared the MATLAB simulation of the refrigeration system evaporator superheat control loop off-line system identification of several commonly used method for the design of refrigeration system controller provides a new idea. Off-line identification and control of the object from the mathematical model of the PID controller parameters are self-optimizing design,[link widoczny dla zalogowanych], and simulation of the refrigeration system evaporator superheat loop in the transition process under step input. Simulation and experimental results show that; in the off-line identification of control objects,[link widoczny dla zalogowanych], the use of MATLAB System Identification Toolbox can come both accurate and simple mathematical model of the object. The establishment of the evaporator superheat and electronic expansion valve input pulse transfer function of the question, the use of PID Optimization Algorithm for the simulation of refrigeration system evaporator superheat loop control, can achieve good control quality reference 1Hew [ttNJetalComparisonofExpansionvalvePerformance. InternationalJournalofEnergyRese & rch, 1995 {(19), UK2 Sun dry brick of new control system of a number of issues. PhD thesis, Shanghai Jiaotong University, 19 983 white Zi Wan. And tie down the development of electronic expansion evaporator superheat in the application of adaptive control of a master's degree thesis,[link widoczny dla zalogowanych], Shanghai Jiaotong University, 1995,[link widoczny dla zalogowanych], 200030, Shanghai Jiaotong University Ho Yu Ling and system engineering of a low-temperature refrigeration system 61 in the non-design conditions and operating characteristics Analysis. Tianjin University, Tianjin fell Keio ink factory Zhang Rongling Abstract fourth semiconductor device cooling system runs through the analysis of the situation, pointing out that non-design conditions in the refrigeration system operating characteristics to buildings prone to problems, these problems should be clarified measures. Keywords Health Mexican Zhu 1 summarizes operating characteristics of non-design conditions and design of the refrigeration system is designed to meet certain working conditions and load the design, but the systems and equipment design conditions are often not in operation, the load is also frequent changes . In fact,[link widoczny dla zalogowanych], every moment of the day, different seasons each year, the refrigeration system load should change. This will undoubtedly be the performance of systems and equipment impact, and even in damage to each. According to blame investigation statistics, the word Beijing Hotel architectural space to run more than 98% of the running in part load], the supermarket refrigeration equipment, medium and large cold storage facilities often operate at part load conditions. - Received: 19990325 In addition, the change will affect the cooling load of the refrigerant in the refrigeration system the flow of Freon cooling system, will directly affect the oil return path back to the trachea, threatening the safety of the compressor; also on with evaporator dispensers role of the sub liquid adverse effects, deterioration of the evaporator heat transfer performance of the system's operation. Therefore, the systematic analysis of refrigeration system operation conditions in the non-design features of the system and equipment operation to identify the root causes of the technical measures to solve problems, will refrigeration equipment, refrigeration equipment and refrigeration system design guide .

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