Simulation Of Dynamic Characteristics Of Evaporators

The thesis does some research on D045-35/15G finned-pipe evaporator, which is produced by Dalian Bingshan Corporation. The thesis focuses on the development of the dynamic simulation model of evaporators, the accomplishment of the stable and dynamic simulation of the parameters of cryogen-side, air-side and how to carry out dynamic simulation on the refrigerating effect of evaporators under different evaporating temperature and the realization of the analyses and calculations of the main parameters, such as, the wind speed of air-side and specific humidity etc, which affect the function of evaporators. According to the simulation of refrigeration system, the thesis applies the dynamic concentrative parameter model and dynamic distribution parameter model to the process of starting, stopping and normal running and validates the correctness, reliability and sensitivity of simulation model by comparing results of simulation calculation with experimental results. What's more, the writer programs the dynamic simulation software for this evaporator. The thesis can be divided into five parts as follows:First, the structural characteristics of finned-pipe evaporator are analyzed. After selecting suitable microelement controller, the heat-transfer and mass-transfer processes are analyzed for every microelement under the conditions of dryness, wetness and frostiness. Based on previous equations, some parameters of frostiness are confirmed and the frost-growing model is set up under frost condition. Some hypotheses are postulated and with the help of the equation of mass-conservation, energy-conservation and momentum-conservation, the evaporation model which fits in the dynamic simulation is built, which set a solid foundation for system simulation.Second, the starting and stopping behaviors under disturbed condition are analyzed and calculated by using the dynamic concentrative parameter model, which gives some advice to better prescribe refrigeration system and set theoretic foundation for carrying out automatic control of refrigeration system.Third, the normal running process is analyzed and calculated by means of rational matching theory, which gives some advice on how to better understand the parameter change under steady state and the affection of inlet-parameter on evaporator.Fourth, the simulation software with dynamic characteristic is designed, which can be applied to calculate thernio-parameter of cryogen, air humidity and frost thickness under different initial and boundary conditions, and to carry out dynamic simulation under conditions of dryness, wetness and frostiness, at the same time, to achieve detection and simulation at any stage from starting to stopping.Fifth, with the comparison between results of simulation calculated and experimental results, the dynamic mathematical model in this thesis is proved to be reliable, correct and sensitive to some parameters. The results can be applied to system simulation.