| In public buildings,the electricity consumption of air conditioning systems accounts for 40-50% of the total building electricity consumption,which will have a serious impact on China’s energy saving and emission reduction targets,and it has become an urgent task to carry out energy saving and emission reduction in buildings.In addition,the application of multi-connector systems in office building air conditioning systems is becoming more and more common,and load prediction is applied to the optimal control of multi-connector systems,and a reasonable combination of optimization algorithms and traditional control strategies,so that it can have a strong adaptability to complex environments,so that the system can have a better control effect and can effectively save energy consumption.Most of the current load prediction models are difficult to function in practical applications,mainly because it is difficult to collect all relevant parameters needed for load prediction dynamically in real time;the indoor units of the new multi-connector system can be installed with infrared temperature sensors and measure the temperature of the inner surface of the external envelope（external walls,external windows,etc.）;the building envelope serves as an intermediate medium between the outdoor and indoor environments,and both indoor factors and outdoor Both indoor and outdoor factors affect the heat transfer process of the envelope,thus affecting the building cooling load.Therefore,it is necessary to study the dynamic change law of the inner surface temperature of the external envelope of office buildings,establish the inner surface temperature prediction model,and reserve the key theoretical basis for the final establishment of the load prediction model.In this study,the influence of many factors on the inner surface of the envelope is obtained through experimental and simulation methods.In the experimental study,the temperature of the inner surface of each envelope is tested in a specific room,and the temperature change process of the outer envelope under the room type is analyzed by outdoor temperature and solar radiation intensity,and the basic law of the inner surface temperature on solar radiation and outdoor air temperature change is derived.For the research which is more difficult to be carried out in the laboratory,we adopted the numerical simulation method.In the numerical simulation,we carried out the research for the office building in Tianjin area,and by setting different simulation conditions,we derived the influence law of many factors on the inner surface of the envelope,and established the prediction model of the inner surface temperature of the outer envelope.The main research contents and conclusions are as follows.（1）By establishing the heat balance equation of the inner surface of the exterior envelope structure and studying the existing literature and theoretical basis,we derived that the larger factors affecting the temperature of the inner surface of the envelope structure are:outdoor air temperature,solar radiation intensity,wall type,window type,room window-to-wall ratio,and indoor heat dissipation.（2）In the experimental study of a specific room in the laboratory,the airtightness of the experimental room was tested to ensure the accuracy of the experiment,and the airtightness class of the room was measured as Class 1.During the experiment,the average temperature of the inner surface of the walls and windows increased with the increase of outdoor air temperature and solar radiation intensity.The temperature change of the inner surface of the windows was more drastic compared with the walls,and the temperature change of the windows was more obvious.In addition,the air conditioning energy consumption also increases,and the effect of indoor heat dissipation on air conditioning energy consumption is also more obvious.（3）in the study of simulation extension,change of outdoor temperature,wall body and form differ from that of the inner surface temperature changes,the window of the inner surface temperature compared to the outer wall inner surface temperature,the change is more obvious,temperature swings,within the external wall surface temperature of inside surface temperature and the form is in with the outdoor temperature rises;With the increase of the intensity of solar radiation within the external wall surface temperature within and outside the window after gradually achieve the stability of the average surface temperature inside surface temperature is rising gradually,inside surface temperature at outside the window is still volatile,when the solar radiation intensity is enhanced,the window inside the average surface temperature rise obviously,when the sun radiation intensity increased from 0 to 450 w/m2,The average temperature of the inner surface of the outer window increased 4.5℃,while the average temperature of the inner surface of the outer wall increased only about 1℃.（4）When the heat transfer coefficient of external wall increases from 0.4W/m2·K to0.6W/m2·K,the difference of internal surface temperature of external wall exceeds 1℃.The temperature change of the inner surface of the outer window is more than 2℃,while the change of the surface temperature of the other inner envelope structure has no obvious influence.When the window heat transfer coefficient reaches 3W/m2·K,the internal surface temperature of the window reaches 34.45℃,and the temperature rise is obvious and the temperature fluctuation is more severe,while the internal surface temperature of the exterior wall basically maintains at about 25.6℃,and other internal surface temperatures also remain basically unchanged.With the increase of room area,the temperature fluctuation of the inner surface of the outer wall and the outer window decreases obviously,and the temperature variation tends to be gentle,while the surface temperature of the inner envelope also has no obvious fluctuation.When the window-wall ratio increased from 0.3to 0.7,the average inner surface temperature of exterior walls decreased by 1.5℃,while the inner surface temperature of exterior Windows first decreased and then increased.When the indoor heat release increased to 2670 W,the internal surface temperature of the external wall increased by about 3℃,while the internal surface temperature of the external window increased by about 2.5℃.The indoor heat source had a significant effect on the internal surface temperature of the external wall.（5）Through linear regression analysis,the standardized coefficient of each influencing factor is obtained,and the contribution rate analysis is conducted.The results show that the internal surface temperature of exterior wall is inversely proportional to the ratio of window to wall,and the contribution rate of each influencing factor to the change of internal surface temperature of exterior wall is in descending order: Indoor heat dissipation,outdoor temperature,window-wall ratio,solar radiation intensity,room area,window heat transfer coefficient and wall heat transfer coefficient.The inner surface temperature of the outer window is positively proportional to the outdoor temperature,solar radiation intensity,room area and indoor heat dissipation,and inversely proportional to the heat transfer coefficient of the outer wall and window and the window-wall ratio.The contribution rate of each factor to the change of external window inner surface temperature is as follows:solar radiation intensity,outdoor air temperature,wall heat transfer coefficient,window heat transfer coefficient,indoor heat dissipation,room area,window-wall ratio.This subject adopts the experimental study and numerical simulation,the method of combining the analysis of the impact factor of external wall and the influence law of the inner surface temperature outside a window,and got the outer wall is established by using the method of mathematical statistics and outside the window the average surface temperature prediction model,and the validation of the model,in addition,also according to the standardized coefficient of the linear regression analyzed impact factor contribution rate,It provides a theoretical basis for the subsequent research on cooling load prediction. |
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