Energy Simulation And Load Analysis For A Large-scale Building Based On EnergyPlus

With the rapid development of global economy and technology,human's demands for energy is increasing,and the imbalance between global energy supply and demand becomes increasingly serious.Due to its complicated physical structures and operational performances,the large-scale buildings,such as large public buildings,have always been the "major energy consuming objects",in which air conditioning systems costs a lot in the total building energy consumption.Therefore,research and exploration of energy consumption of the air conditioning systems for these kinds of buildings has attracted wide concern of the scholars all over the world.As a fully functional energy consumption simulation software,EnergyPlus uses three modules of load,system and equipment to integrate and synchronize the solutions,which makes the results more accurate.It also contains cell modules which can deal with thermal stratification,and has certain advantages in the simulation of energy consumption in large-scale buildings.So,this paper will take the large-scale engineering training center in USST as a prototype and the CNC machine tool experimentation area will be chosen as the research object.The research purpose will be served by establishing the simulation model using EnergyPlus and verifying this model in comparison with experimental results.In this paper,a three-dimensional geometric model of the target building is established by using SketchUp.The combined and independent operation of the ground source heat pump and air source heat pump under the experimental conditions is realized with the basic module of EnergyPlus.Two modeling methods of single-zone model and double-zone model are used to consider the large space as a whole or partition.The vertical temperature distribution in the large space is described by using the expression of the dimensionless height temperature mode(Room Air: Temperature Pattern: Nondimensional height)in the Room Air module to realize the establishment of the simulation model for energy consumption of the large-scale building with consideration of its temperature gradient.Through the field measurement under typical working conditions of the target building in winter and summer,the relevant data collected in the experimental process are integrated and used as the input basis for the boundary conditions of the energy simulation model and the reference basis for the later comparison and verification.The Verification between simulation results and experimental data,shows that the maximum error between the simulated and experimental values of the hourly indoor air temperature under 4 typical working conditions in winter and summer is within 1 centigrade.The average errors between the simulated and the experimental load of the single zone model and the double zone model under 4 typical conditions are within 15%,which also gets the same tendency in the running time.It can be considered that the two modeling methods can both well satisfy the verification requirements.However,there exists some differences between the simulated and experimental results in system's Coefficient of Performance(COP)under heating or cooling conditions.It may be caused by the mismatch of performance in the simulation,which follows the principle of software synchronous integration,and the experiment which shows the imbalance of supplies and demands in the air side of the system and the water side of the plant probably caused by the heat loss and air leakage in the air supply and cold transport process.At this point,the cooling and heating capacities are corrected based on this phenomenon.Therefore,the comparison between the simulation and experiment proves that the accuracy of the energy simulation model is basically explained.Based on the validation of the model,the effect of room air thermal stratification acting on the load validation under typical operation conditions in winter and summer is discussed.It is concluded that the simulation model of energy consumption of Room Air used in the simulation of summer working conditions is relatively small.The error between the simulated value of cold load and the experimental value is close to the two cases.The output heat load of the energy simulation model using Room Air in the winter working condition simulation is slightly higher than that of the unused condition and the experimental value of the heat load.The error of the interval is slightly less than that of the unused case.Therefore,considering the influence of vertical temperature distribution is conducive to the simulation and prediction of the two quarter load in winter and summer.In addition,the EnergyPlus ideal load system model are used in this paper,and combined with double-zone model and triple-zone model,the ratio of the non-airconditioned zone loads which is converted into the total loads of the central air conditioning system under the typical working conditions is studied,referring to the traditional load calculation method of large-scale buildings with stratified air conditioning system.On the basis of these models,the paper lately discusses the influence of the roof heat transfer coefficient on the non-air-conditioned load.It is found that in double-zone model there is a proportional relationship between the nonair-conditioned load and the roof heat transfer coefficient when the design parameters of the indoor thermal environment are constant.It also indicates that he outdoor weather conditions have a significant influence on the load of the non-air conditioned area.In the triple-zone model,the change of roof heat transfer coefficient mainly affects the thermal load in the top area,and its regulation is similar to that of the double-zone model.In addition,the reasonable value of air flow and mixing between the airconditioned area and non air-conditioned region(triple-zone model as the middle convective area)is discussed by using the double-zone and triple-zone model in the typical summer conditions.The reasonable value of Zone Mixing module which describing the air flow and mixing between the non-air-conditioned zone and airconditioned zone is also discussed in the last chapter.