Temperature And Humidity Control Of Clean Central Air-Conditioning System & Energy-saving Research And Implementation

At present, clean air-conditioning is widely applied in all kinds of industries, such as medicine & chemical industry, mechanical electronics and aerospace. But, the precision of temperature and humidity control of air-conditioner can not meet the system requriment. The reason is that air-conditioner is a time variant, nonlinear and time delay system, better performance is too difficult to get by using conventional control strategy. Meanwhile, compared with the civilian air-conditioning, energy waste of clean air-conditioning is obvious, because of various reasons.In this paper, firstly, using a clean air-conditioning of an electronic industries plant in Xi'an as an example, temperature and humidity control method of clean air-conditioning is described, and the result of project is showed, too. Next, the model (The first order plus delay model) between chilled water valve opening and room temperature is identificated with least-squares method, using matlab6.0. And it is used for system simulation.At the beginning of chapter 4, SMITH control principle is introduced。To enhance system stability, the control principle is improved by adding the weighted average filter in forecast error loop. Then the basic theory of fuzzy control and fuzzy adaptive PID algorithm principle are introduced. Aiming at the model between chilled water valve opening and room temperature, fuzzy adaptive PID + improved SMITH forecast control method is adopted. And good control is got in system simulation using matlab.Last, dissertation analyses one reason of energy waste of temperature and humidity control in clean central air-conditioning system. In order to overcome it, a control thought of cooling PID and heating PID interlocking, wetting PID and dehumidification PID interlocking is proposed. In addition, how should choice SP in these 4 PIDs reasonably is discussed for saving energy. Finally, fuzzy adaptive PID is used in PID interlocking thought, applied on clean air-conditioning of a Pharmaceutical company in Xi'an, and gets perfect performance.