Coupling Dynamic Simulation Of Nonuniform Indoor Thermal Environment And Energy Consumption In Large Spaces

With acceleration of urbanization,large spaces have become one of the most significant architectural forms in modern civilian buildings,especially in public buildings.However,large spaces feature high ceilings and large volumes.Usually,their internal airflow process is complicated and the thermal environment is nonuniform and dynamics.Because of insufficient study data and immature research methods,it is difficult to decide how to take good advantage of climatic and local conditions.Especially,there is a challenge facing us of higher requirements about thermal comfort and building energy conservation.As a transitional method between the macroscopic nodal model and microscopic computational fluid dynamics(CFD),the zonal model is able to effectively balance computational efficiency and accuracy.However,its simulation performance is still inadequate,and thus it is necessary to explore its application potential for large spaces,especially the coupling analysis of airflow and energy consumption.Therefore,this thesis focuses on civilian large space buildings.Field measurements,model experiments and zonal simulations were combined,thereby improving the theory about indoor thermal environment in large spaces and developing the auxiliary analysis tool of building microclimate and energy consumption.Firstly,on-site measurements of the indoor environment were conducted in a typical atrium in the severe cold region,in order to obtain the spatial-temporal characteristics and influential factors of large spaces.During winter and summer respectively,a large number of temperature-measuring points were arranged in the three-dimensional space of the atrium.The dynamic heat balance method was mainly utilized to analyze the hourly air infiltration with the complex airtightness and building layout.The results indicated that even in the severe cold region,solar radiation through the skylight in summer exerted influence,so that the indoor environment showed thermal nonuniformity and the upper space was overheated.In winter,the under-floor heating system was adopted,and thus the indoor environment was more uniform and stable.The total air infiltration of the isolated atrium in this climate zone was less significant than that of common buildings,nevertheless the corresponding heat loss cannot be ignored.Secondly,reduced-scale model experiments were resorted to analyze the ventilation in the thermally stratified environment of large spaces.The building prototype and environmental parameters in the measurement were referred to.The crucial factors such as solar radiation,internal heat sources and heat transfer through building envelopes were comprehensively considered.The overall thermal stratification of large spaces was replicated based on similarity theory.The measurements were conducted by combining the distributed measurement with representative measuring points and the global visualization technique with particle image velocimetry(PIV).It was found that the thermal plumes of multiple heat sources and the ventilation jet interfered mutually,resulting in airflow deformation and energy redistribution.There was a thin buoyant air layer with a high temperature nearby the roof,which played an important role in the developments of thermal stratification and natural ventilation in large spaces.Thirdly,when balancing computational accuracy and efficiency,the framework of the dynamic zonal model for large spaces was established.The airflow zonal network was constructed inside the large space and the simplified momentum equation was established.The length of airflow path,characteristic velocity,apparent viscosity and heat flux coefficient were introduced.In this way,the zonal model can solve the inhomogeneous distribution of air parameters and the complex airflow phenomena regarding the conservation,conversion and dissipation of kinetic energy along the way.Through the theoretical analysis of the previous measurements and experiments,the calculation model expanded the modules of natural ventilation,air infiltration,mechanical ventilation,and temperature-feedback coupling analysis in large spaces,thereby improving its reliability and applicability.On this basis,a coupling algorithm for the new generation of the zonal model was proposed to solve the velocity-pressure coupling problem.The ill-conditioned problem was regularized by the linearization and energy functional method,so as to ensure computational efficiency and robustness.Furthermore,based on the field measurements,reduced-scale model experiments with PIV and CFD simulations,the dynamic zonal model about the indoor thermal environment in large spaces was analyzed in terms of computational accuracy and efficiency.Four cases were studied,including natural convection,air infiltration,natural ventilation and mechanical ventilation under complex thermal boundary conditions.In the light of stratified flow and energy migration,this thesis then discussed the apparent viscosity,heat flux coefficient,thermally stratified boundary conditions and adaptive zoning strategy in the zonal simulation of large spaces.The evaluation methods and results had a good reference for the future zonal simulation of large spaces.Especially,the PIV airflow dataset enabled the analysis of the characteristics of the zonal model.Finally,the dynamic zonal model of large spaces and the building energy consumption model of De ST software were coupled to realize the long-term dynamic simulation of large space buildings with double-scale air flow and heat transfer.The former calculated the detailed thermal condition of the large space,while the latter focused on the surrounding common rooms and provided the requisite building model and boundary information for the former.The coupling scheme adopted the master-slave mode.A plenty of data was exchanged through the FMI/FMU interface.The chronological coupling and iterative mechanism was complied to.Subsequently,the coupling model was applied to the office atrium in the cold region and the large underground public transport hub in the hot-summer and warm-winter region,thereby simulating the dynamic and inhomogeneous building energy consumption and optimizing the design schemes of stratified air-conditioning systems.In conclusion,this thesis focuses on civilian large space buildings.The field measurements of the actual building and reduced-scale model experiments with PIV were combined to analyze the dynamic,nonuniform indoor thermal environment and their corresponding influencing factors.In the premise of computational accuracy and efficiency,the framework of the dynamic zonal model for large spaces was established and coupled with the annual building energy simulation model.As a result,this study can provide theoretical guidance and technical support for hospitable indoor environment,improved life quality,and sustainable social development.