CFD Simulation Of Air Distribution Of Lanzhou Jiaotong University Convention And Exhibition Center Lecture Hall

In recent years, with the convening of large-scale academic reports and academic lectures, lecture halls play an more and more important role in universities, the indoor temperature and humidity and cleanliness has also been widely valued. Airflow as an important part of air-conditioning, it has a decisive influence for thermal comfort and indoor air quality, directly related to the indoor temperature, humidity, cleanliness, air velocity and air conditioning energy consumption, etc. Because of some problems, the central air conditioning system of Lanzhou jiaotong university international convention centre lecture hall has not played its role, it uses five cabinet air conditioners take the place of central air conditioning in recent years. However, for such a large volume and so crowded public space, using cabinet air conditioners clearly does not meet the requirements of comfort, and energy consumption is also very serious. In order to find the crucial reason of the undesirable air conditioning system, this paper use FLUENT software, do three-dimensional simulation of the temperature, velocity and CO2 concentration under different forms, and deal with the final results after the calculation process.In this paper, six airflow schemes were selected, the outsize is 240 mm × 240 mm, and the airflow form is upper supply and upper return, the outsize is 300 mm × 300 mm, and the airflow form is upper supply and upper return, the outsize is 360 mm × 360 mm, and the airflow form is upper supply and upper return, the outsize is 240 mm × 240 mm, and the airflow form is upper supply and lower return, the outsize is 300 mm × 300 mm, and the airflow form is upper supply and lower return, the outsize is 360 mm × 360 mm, and the airflow form is upper supply and lower return. All the air supply outlet are square diffuser. Return air mouth is single-layer grating type inlet, the position of return air mouth in the upper supply and upper return airflow form is in the 1 m under the roof, the size is 900 mm * 600 mm; and in the 1 m under the roof in the upper supply and lower return airflow form, the size is 1200 mm * 600 mm. Selected three typical sections of the model, compared the changes under three sections of speed, temperature and CO2 concentration in the six programs respectively, analyzed final results, and then evaluated the airflow by technical indicators and economic indicators. We can get the following conclusions:(1) Due to the lecture hall is a large space, when the airflow form is upper supply and upper return, and the air velocity is small, indoor air and fresh air is too late to have an adequately heat exchange, the fresh air will be exhausted to the outside, lead both temperature and CO2 concentrations too high, can’t meet the design requirements; and a high speed air easily make people a sense of blowing, does not meet the comfort requirements.(2) In the form of upper supply and lower return, air circulation can be sufficient exchange with the indoor air, so the CO2 emission is very favorable. When the air speed is high, people will have a blowing feeling; when the air velocity is small, thermal comfort and indoor air quality can be reached.(3) The best scheme of upper supply and upper return form is program two, and the best scheme of upper supply and lower return is program six. Compared program two with program six, it were found that despite the air velocity of program six is less than programs second, but because of the different forms of airflow, the air quality of program six still better than program two. It can be obtained that the airflow form is the most crucial factor in determining the air quality.(4) Evaluated the six airflow programs, it is concluded that the temperature and velocity uniformity coefficient of program one and program six were lower than the other four programs. But the measuring points conform to the proportion of a given condition of program one is less than program six, and energy efficiency is much lower than the scheme six. Although the Energy efficiency of programs three is high, but other parameters of program three do not meet the requirements. The comfort and economy of other several schemes are poor. therefore, program six is the most suitable for the lecture hall.