Dynamic Simulation Of Spinning Air Conditioning System And Research On Automatic Control Strategy Of Temperature And Humidity

The textile industry is an important part of industrial development and livelihood security,and an important supporting industry for national economic development.At present,there are problems in the spinning workshop,such as large energy consumption of air conditioning system,unstable temperature and humidity control,and imperfect automatic control strategy.Therefore,in order to improve the stability of temperature and humidity automatic control in spinning workshop and realize energy saving and emission reduction of spinning air conditioning system,the mathematical model of spinning air conditioning system was established.Meanwhile,the dynamic simulation platform of spinning air conditioning system was established by using programming language,so as to study the dynamic change law of temperature and humidity in spinning workshop and provide operation platform for automatic control strategy of air conditioning system.The specific research contents are as follows:The white-box model was used to decompose the complex mathematical model of air conditioning system into several interconnected sub-models.Based on heat balance,moisture balance and air volume balance,the heat and moisture exchange mathematical model of spray chamber and the mathematical model of air conditioning system in spinning workshop are established respectively.The differential equations of heat and moisture balance of the spinning air conditioning system with temperature and humidity response were solved analytically.The business logic programming was realized by Python,and the graphical user interface was developed by PyQt5.Based on the structural parameters,process and air conditioning equipment parameters of a spinning workshop,the dynamic simulation platform of spinning air conditioning system was developed.The variation of temperature and humidity in the workshop was simulated and calculated after changing the control parameters of air conditioning equipment.The variation trend and law of the dew point of the spray chamber machine and the temperature and humidity in the workshop were analyzed.The results show that the dew point temperature of the spray chamber machine and the moisture content of the supply air change with fresh air volume which affecting the temperature and humidity of the workshop.The increase of the opening of the secondary return air valve which increasing the secondary return air volume can increase the temperature of the workshop and reduce the relative humidity.The increase of fan frequency leads to the increase of the supply air volume which reducing the temperature of the workshop and increasing the relative humidity.The increase of pump frequency enhances the heat and moisture treatment.The moisture content and relative humidity in the workshop increase with the increase of pump frequency.When the temperature and humidity of the workshop deviate from the set value,the control parameters of the air conditioning equipment can be adjusted by the simulation platform.The system of air conditioning can adjust quickly the temperature and humidity of the workshop to the set range.The dynamic simulation platform of spinning air conditioning system can calculate the dynamic changes of machine dew point,temperature and humidity of the workshop and the response time when the temperature and humidity are stable.On this basis,the relevant research on the control strategy of air conditioning system can be carried out.Based on the dynamic simulation platform of spinning air conditioning system,the change law of steady-state response of temperature and humidity in workshop was studied after the parameters of air conditioning equipment and the setting values of temperature and humidity were modified.The temperature and humidity control was decomposed into two relatively independent loops.The control strategies of variable air volume and variable dew point fresh air were formulated.The automatic temperature adjustment of workshop was realized by the opening control of fresh air valve on the basis of enthalpy difference.Following the energy-saving principle of“increasing the small and decreasing the large”,the relative humidity of the workshop was automatically adjusted by regulating the power equipment(secondary return valve,the pump and fan)according to the relative humidity deviation sequence.According to the temperature and relative humidity control strategy of the air conditioning system in the uncooled season,the Python/PyQt5 object-oriented method was used to develop the automatic controlled dynamic simulation program of the spinning air conditioning system combined with the incremental PID control algorithm,.In order to improve the control precision,the variable parameter PID control algorithm was adopted to optimize the simulation program.The change trend of temperature and humidity was predicted on the basis of BP neural network algorithm.The results show that the automatic control system of spinning air conditioning with incremental PID control algorithm can control the actuator according to the established automatic control strategy and make the temperature and humidity of the workshop stable near the threshold.After the optimization of variable parameter PID control algorithm,the control accuracy is stable in the range of threshold [-0.3,0.3].The response time of stable temperature and humidity is shorter than that of incremental PID control algorithm.The BP neural network can accurately predict the variation of temperature and humidity,and then adjust the actuator in advance according to the control strategy.It can alleviate the time lag problem of temperature and humidity in the workshop.The dynamic simulation program can realize the virtual operating environment of spinning air conditioning system.It can also provide technical support for the optimization of control strategy,the setting of automatic control PID parameters and the advance control of actuator.