| The atrium of the office building can be used as a transportation area and also has both rest and leisure functions.However,its shape and large size produce two special phenomena,the chimney effect and the greenhouse effect.In order to solve the thermal environment problems caused by these two phenomena,high energy consumption methods such as air conditioning are often used,however,it neglects the use of natural ventilation as a clean energy.In this paper,the method of combining numerical simulation and experiment is used to study the driving force and influencing factors of natural ventilation in the atrium of office buildings in the severely cold Class C area in all seasons and periods,which is of great significance for improving the thermal environment of the atrium space and reducing the energy consumption of air conditioning.First of all,the research and analysis of the office building atrium buildings in Hohhot,a typical city in the severely cold C region,select representative office building atrium buildings for numerical simulation and related experiments with different boundary conditions in four seasons.The simulation results agree well with the experimental results.In spring,the average wind speed is 2.5m/s and the atrium wind pressure ventilation accounts for 78% of the whole season.With the increase of outdoor wind speed,the indoor wind speed and the amount of ventilation increases.When the outdoor temperature is higher than 18.0? between 12:00-18:00,increase the opening for natural ventilation,which is helpful for indoor air circulation.The indoor wind speed is below 1.5m/s and the temperature in the atrium indoor can be increased by 1.2? in spring,the indoor relative humidity is between 32% and 46%,which is relatively comfortable.In summer,the average outdoor wind speed is 1.8m/s and the thermal stratification in the atrium is obvious.Increasing the indoor and outdoor temperature difference and the width of the air outlet can strongly increase the heat and pressure ventilation and effectively reduce the indoor temperature.Through experiments,it was found that the temperature difference between indoor and outdoor during the summer is small,and the hot pressure ventilation is not obvious,the wind pressure ventilation still accounts for 65% of the entire season.When the temperature difference between indoor and outdoor is small,and the outdoor temperature is too high,the opening should be closed;take shading measures,the air temperature above 6m can be reduced by more than 3.5?;the indoor and outdoor temperature difference at night is large,Hot-pressed ventilation can be used,and the temperature drops by 0.8?,indoor relative humidity is between 46% and 53%,comfortable.In autumn,the average outdoor wind speed is 1.7m/s,however,the dominant wind direction is different,and its angle to the windward side of the building is greater than 45 °,which helps to enhance the wind pressure ventilation.Most of the time,the indoor wind speed is between 0.4m/s and 0.6m/s,The maximum wind speed value is 0.6m/s,and the mixed ventilation of wind pressure and heat pressure from 14:00-15:00 can also increase the disturbance of the indoor wind environment,reduce the average temperature of the atrium space,and reduce indoor thermal stratification,the indoor humidity is between 35% and 43%,which is relatively comfortable.In winter,when the opening is in the main wind upward,the wind direction is at an angle of 90 ° to the windward surface of the building.When the wind speed reaches the maximum,a large amount of cold air will enter,causing the temperature of the atrium space to drop rapidly,which is not conducive to the comfort of the indoor thermal environment.And the temperature difference between indoor and outdoor is the largest in winter,the atrium is dominated by hot-pressed ventilation.In order to meet the required ventilation volume of the atrium,the effective area of the opening should be increased for natural ventilation when the outdoor wind speed is less than 1.5m/s,and the time should be less than 1 hour,the relative humidity in daytime is less than 30%,the air is dry,the relative humidity at night is between 30% and 44%,and the humidity is suitable.Through numerical simulation and experimental results,it can be seen that the natural ventilation of the atrium is affected by many factors such as the outdoor wind speed,the angle between the outdoor wind and the windward surface of the building,the width of the opening,the height of the opening,and other factors.Using orthogonal analysis,the opening width is the main influencing factor of natural ventilation,followed by the opening height and opening angle.In the design and renovation of the atrium of the office building in the future,these three factors can be changed to improve the indoor thermal environment of the atrium and improve comfort. |
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