Research On ANSYS Simulation And Control System Of Solar Water Heater Mixing Valve

When the pressure difference between the cold and hot water from the solar water heater is large,the water outlet temperature of the mixing valve will fluctuate greatly.In order to solve the problem of the difficulty of adjusting the outlet temperature of the mixing valve,the new structure of the mixing valve and its control system is studied.(1)Improved the structure of the thermostatic mixing valve of the solar water heater.Build on the research of the traditional water mixing valve structure,a water mixing valve chamber structure with a water pressure balance unit is proposed.Aiming at the problem of damage or sudden power failure of the automatic temperature adjustment device during use,the structure of the automatic and manual temperature adjustment mixing valve is studied,and the thermostatic mixing valve that combines automatic temperature adjustment and manual temperature adjustment is studied.This is by design.(2)Simulated the internal flow field of the mixing valve.Based on the ANSYS Fluent simulation platform,the actual force of the bellows valve in the mixing valve was simulated,and the thickness of the bellows membrane was established by analyzing the simulation results.Based on the ANSYS Fluent simulation platform,the internal flow field of the traditional mixing valve and the improved mixing valve was numerically simulated,and the static pressure cloud diagram,and the velocity vector diagram.The simulation results show that the improved water mixing valve can effectively balance the pressure of cold and hot water,and address the problem that the outlet temperature of the water mixing valve changes with the change of external water pressure.(3)Researched the thermostatic mixing valve control system model and temperature control algorithm.According to the equations of fluid mechanics and the law of conservation of physics,the thermostatic mixing valve control system model is constructed,and the thermostatic mixing valve control system model is fitted to the second-order inertia link with pure lag using the two-point method.The model is solved based on MATLAB software,and the result is the Approximate transfer function of the controlled object.The thermostatic mixing valve temperature control algorithm is studied,the Smith fuzzy PID temperature control algorithm with the variable universe is designed,and the mixing valve temperature control algorithm is simulated based on the Simulink simulation platform.The simulation results show that the Smith fuzzy PID temperature control algorithm with the variable universe has More ideal steady-state quality: faster adjustment speed,stronger anti-interference ability,and smaller oscillation amplitude.(4)Designed the thermostatic water mixing valve control system of the solar water heater.The thermostatic mixing valve control system uses STM32 as the main controller chip.The system has functions such as automatic temperature adjustment,heat collection tube protection,and heating cable protection.Based on the proteus 8.9 simulation platform,a thermostatic mixing valve control system for simulation is constructed.Test the control performance of the thermostatic mixing valve by changing the temperature value,observing the adjustment of the water outlet temperature of the mixing valve,and the angle adjustment of the stepping motor.The results show that in the process of large temperature difference adjustment,the mixing valve has a fast response speed and can be adjusted in time.The outlet water temperature of the mixing valve quickly stabilizes near the set temperature.The stepper motor angle can be adapted in time,and it can quickly return to a stable working state.