| In recent years,radiant floor heating system is more and more favored by heating users with its advantages of comfort,high efficiency and energy saving,in addition,radiant floor heating system can also make use of low-grade heat sources and effectively utilize renewable energy sources such as geothermal energy and solar energy to promote the carbon neutral goal in the field of building air conditioning in China as soon as possible.Radiant floor heating system is becoming more and more prominent in the intermittent heating operation of residential buildings in southern regions due to its large thermal inertia and strong dynamic delay.To solve the problems of slow thermal response and high energy consumption of radiant floor heating system,the state space thermal model of radiant floor heating system is established,the accuracy of the model is verified by the experimental platform of radiant floor heating system,and the simulation platform for optimal control of radiant floor heating system of air-source heat pump is established based on the simplified processing of the state space thermal model of radiant floor by applying the model reduction technique.The optimization research is carried out for the model prediction control method of the radiant floor heating system of residential buildings in the southern region.The main research contents and innovation points of the paper are as follows.(1)A 3-dimensional radiant floor state space thermal model with built-in heat sources was developed using the state space method.Unlike the existing energy consumption simulation software such as Energy Plus or TRNSYS,which use the transfer function method to model the radiant floor room state space thermal model,this study uses the state space method suitable for multi-input and multi-output coupled systems to establish the radiant floor room state space thermal model.Most of the existing models of radiant floor heating systems assume uniform and constant water temperature in the radiant tubes in the room,without considering the non-uniform variation of water temperature during the operation of the radiant floor system.In this study,the convection and thermal conductivity processes of the core temperature layer and other structural layers within the radiant floor are analyzed from the state space method,and a 3-dimensional radiant floor state space thermal model with the heat source built into the envelope is established.(2)The state space model of the established radiant floor heating system is analyzed by using RC heat transfer model analysis method,and the multi-region radiant floor state space thermal model and its coefficient matrix are obtained.The coupled heat transfer processes such as radiative heat transfer process between radiant floor and other enclosure structures,convective heat transfer between enclosure structures and indoor air nodes are analyzed,and the state space thermal models of radiant floor,wall and indoor air nodes are jointly established,and the state space thermal model of multi-region radiant floor room and its heat transfer matrix are obtained,which lays the theoretical model foundation for the control optimization of the system.Meanwhile,the accuracy of the state space model established in this study is effectively verified by building an experimental platform for capillary radiant floor heating system.(3)The balanced truncation method was used to downscale the state space model of the multi-region radiant floor room.The state space thermal model of the radiant floor room was analyzed for controllable observability,and the Hankel singularity matrix of the model was obtained on the basis of the equilibrium controllable observable Gram matrix,and the Hankel singularity value is an important basis for judging the accuracy of the reduced-order model.On the basis of maintaining the dynamic performance of the full-order model,the reduced-order model of radiant floor heating room is obtained,and the computational efficiency is greatly improved,which provides technical feasibility for the application of the model to heat source control.(4)The core algorithm of MPC controller for radiant floor heating system with air-source heat pump is designed.Based on the establishment of a simulation platform for the air-source heat pump radiant floor heating system,start-stop control,PID control,MPC control and duty heating + MPC control are designed,and the operational performance of the air-source heat pump radiant floor heating system under these four control methods is compared and analyzed.The steady-state error of indoor air temperature,overshoot,thermal response time,peak system load,energy consumption and energy efficiency ratio COP of the air-source heat pump are compared and analyzed.Using the advantages of rolling optimization of model predictive control to improve the adaptability of MPC control to the heat load of radiant floor system,the water temperature of the air-source heat pump can be adjusted in real time according to the size of the building heat load to improve the system energy consumption with good energy saving effect.In addition,the duty heating + MPC control method can reduce the steady-state error and overshoot of the system,greatly reduce the system thermal response time and peak load,improve the system energy efficiency,and achieve significant energy savings. |
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