Simulation Of Indoor Thermal And Humid Environment And Analysis On Energy Consumpyion Of Stratified Air Conditioning System In Large Spaces

With the expansion of the scale of transportation hub buildings such as railway stations and terminal buildings,their waiting halls,which are mostly large spaces,often have large-area light-transmitting envelopes,large numbers of indoor personnel and huge light loads.The energy consumption of the air-conditioning system in the waiting hall is too high.Therefore,it is suitable to apply stratified air-conditioning with significant energy-saving effects to the large spaces.The air-conditioning area is controlled at the height of personnel activity to reduce the load,thereby achieving energy-saving purposes.This paper takes the waiting hall of Nanjing South Railway Station as the research object.For the all-air system(referred as to AAs)and the floor radiation and wall radiation combined with air supply system(referred as to FR/WR/ASs),software is used to simulate the indoor hot and humid environment of the waiting hall in the winter and summer,and the corresponding energy consumptions of the AAs and FR/WR/ASs are calculated respectivey.First,the thesis studies the indoor thermal and humid environment of the all-air system in the summer waiting hall through practical tests and numerical simulations.According to the measured data,the boundary conditions are set,and the measured data are compared with the simulation results to verify the correctness of the model.Then,the air supply temperature,air supply speed and air supply angle are adjusted respectively to study the air distribution of the AAs.As the temperature difference of the supply air decreases,the average temperature of each section gradually rises,the temperature of the working area in each working condition is basically between 25℃ and 28℃,while the average temperature at the height of 0.4m is higher than 28 ℃.In summer,the air distribution of the AAs is more reasonable.Except for the higher temperature near the ground area,it can basically meet the indoor temperature and humidity requirements,so only the thermal environment near the ground area needs to be optimized.In order to compare with the AAs,the temperature and humidity distribution of the FR/WR/ASs in summer was simulated under the same condition.By adjusting the size of the air supply port,the air supply speed of the air column in each working condition is consistent with the AAs.According to the different proportions of the radiation system bearing the load of the envelope structure,the temperature and humidity distribution of the FR/WR/ASs was studied.When the radiation system bears the 80% load of the envelope structures,the average temperature is the lowest.The indoor temperature rises as the surface temperature of the radiant panel rises.The higher the vertical height of the area below 2m is,the higher the temperature and the lower the relative humidity are.The temperature near the ground is about25 ℃,and the relative humidity is 55%.The vertical temperature gradient is small,and the temperature difference is less than 1.5 ℃ in the FR/WR/ASs.As the emissivity of the radiant panel surface increases,the cooling capacity of the composite system increases,and when the emissivity is greater than 0.7,the increase in cooling capacity is more obvious.Therefore,the air distribution of the FR/WR/ASs is more uniform,and the heat and humidity environment near the ground area is significantly improved.The stratified air-conditioning system of waiting hall in winter basically meets the requirements under two different terminal forms.In the AAs,as the supply air temperature increases,the indoor temperature gradually rises;the relative humidity gradually decreases;and there are-0.8 <PMV <-0.6 and 14% <PPD <21% under each working condition.Other parameters remain unchanged,and the air supply angle is adjusted.The study found that indoor temperature and relative humidity are greatly affected by the air supply angle.When the air supply angle is 30° downward,the thermal comfort is the best.In the FR/WR/ASs,there are-0.5 <PMV <-0.2 and 8% <PPD <12% under each working condition.The indoor vertical temperature difference in the working area is small,and the temperature difference between the Z = 2m section and the Z = 0.4 section is less than 0.5 ℃.The FR/WR/ASs increases the near-ground temperature of the AAs,and the phenomenon of "hot head and feet cool" is improved,which makes people feel more comfortable.By comparing the indoor hot and humid environment between the AAs and FR/WR/ASs in the waiting hall in winter and summer,the FR/WR/ASs has obvious advantages in winter,because the indoor vertical temperature difference is small,and the environment is comfortable.The radiation energy consumption of the FR/WR/ASs is 18.03% less than that of the AAs in summer,and 66.67% in winter,and 28.96% in energy consumption of the air-conditioning system throughout the year.The results of this paper can provide ideas for the application research of the floor radiation and wall radiation combined with air supply system in the large space buildings.