Research On Over And Under Heating Mode Of Nearly Zero Energy Residential Buildings In Severe Cold Regions

In recent years,the scale of wind power generation in China has been increasing.Due to the weak regulation ability of power grids in the northern region,and the problem of combined heat and power to fix power by heat,the phenomenon of wind power abandonment in northern China is serious.At the same time,recently,nearly zero energy buildings(NZEB)have been developed vigorously in the north of China.The building structure of NZEB has good thermal storage characteristics.If the unstable wind power is stored in the building body in the form of thermal energy and the released for heating,it can not only realize the wind power consumption and clean heating,reduce the phenomenon of wind power abandonment,but also can reduce the consumption of fossil energy for heating in the north.Based on this,aiming at neatly zero energy residential buildings in severe cold regions,this thesis studies the effects of short-term over and under-heating on indoor thermal environment and energy consumption in the case of typical rooms with different modes in Harbin,and explores the operating mode of the heating system.And the theoretical support for the operation of active elastic heating system is provided for NZEBs in severe cold regions.Firstly,this thesis analyses the characteristics of NZEBs in severe cold regions.The numerical simulation model of typical rooms of nearly zero energy residential buildings is establised,and the model is simplified.Considering the heat storage characteristics of the room,appropriate boundary conditions are selected.At the same time,independent validation of grid and time step is carried out to ensure the accuracy of the model.Then based on the numerical simulation model,in radiator heating room and floor radiant heating room,the change rules of indoor temperature,heat transfer capacity and heat storage and discharge capacity of exterior wall are simulated in the case of over/under-heating.The indoor temperature change rule and heating operation time in different heating conditions are studied,and the effects of different insulation forms of exterior walls and different heating terminals are analyzed.It is found that the greater the heat supply,the shorter the heating operation time of the room.In the same heat supply condition,the heating operation time of the external thermal insulation room is longer than the internal thermal insulation room.And the heating operation time of the floor radiant heating room is longer than the radiatior heating room.Finally,the characteristics of over/under-heating room are analyzed from three aspects: heating time ratio,room heat storage capacity and room energy consumption.It is found that the larger the heat supply,the smaller the heating time ratio is,and the more the heat storage capacity is.The lager the heat supply,during the heating and shutdown period the smaller the average energy consumption of the room is,and the energy consumption of the over/under-heating mode is less than the continuous heating mode.Through the study of different types of typical rooms,the influence of external wall insulation form on heat storage and energy consumption of rooms is analyzed.It is found that the external thermal insulation wall is more conducive to building energy conservation.