Research On Efficient Household Fresh Air System Based On Foam Metal

After recent decades of development,the function of household fresh air system gradually tends to perfect,it has basically met the needs of air filtration,heat exchange,and it has the advantages of stable operation,low noise,long service life,low power consumption,etc.,but at the same time there are still a variety of disadvantages,such as the blockage of the heat exchanger paper core will seriously affect the air flow and the heat transfer performance;the narrow flow channel of the total heat exchanger will lose a lot of energy in the case of fresh air only;the heat exchange system has low heat transfer efficiency due to poor thermal conductivity of heat transfer materials;some temperature control methods have low control accuracy and take too long to reach stability.Therefore,this paper optimizes the household fresh air system,designs the household foam metal fresh air system with higher heat transfer efficiency and more intelligent control,and studies its flow,heat transfer and temperature control system to lay the foundation for the future development of more efficient and energy-saving household fresh air system.Firstly,the existing household fresh air system in the market is studied and a new threedimensional structure model of the household fresh air system is designed,then the internal heat exchanger is analyzed and the foam metal heat exchanger is designed,and finally the household foam metal fresh air system is designed.The heat exchanger is studied,the simulation model is made by simplifying the threedimensional structure,and the simulation analyses are carried out for the common heat exchanger and the foam metal heat exchanger respectively to study the heat transfer flow,the force of the spacer and the plate fin,and to verify the feasibility of the foam metal structure design.On the basis of the heat exchanger research,the fresh air system is studied,and the simulation models of common fresh air system and foam metal fresh air system are designed.The heat transfer efficiency of the fresh air system is simulated and calculated under different wind speeds and temperatures,and the air flow is analyzed by the pressure drop calculation.And it is concluded that the foam metal fresh air system has slightly higher flow resistance but higher heat transfer efficiency than the common fresh air system.The mathematical modeling of the temperature control system of the fresh air system is conducted,and the traditional temperature control algorithm is improved based on the unstable characteristics of the fresh air system.By combining Smith predictive compensation with fuzzy control,a new temperature control strategy is designed.Three control methods such as,conventional PID control,fuzzy PID control,and Smith fuzzy PID control,are simulated and analyzed respectively.The results show that the Smith fuzzy PID control method has the advantages of strong anti-interference ability,no overshoot,and fewer oscillations.Finally,a two-room experimental platform for the fresh air system is established,and temperatures at each air outlet of the common fresh air system and the foam metal fresh air system are measured under different wind speeds and temperatures.Relevant experimental data are analyzed to verify the influence of wind speeds and temperatures on the heat exchange efficiency of the fresh air system.The experimental results show that the foam metal fresh air system exhibits higher heat exchange efficiency than the common fresh air system.To sum up,this paper designs a household foam metal fresh air system,and verifies that the foam metal fresh air system has higher heat exchange performance than the common fresh air system through simulation analyses and experiments.At the same time,a new control strategy is proposed to optimize the temperature control algorithm to improve the intelligence of temperature control.