Research On The Effect Of The Air Cooling From Underground Tunnels' Shape And Ventilation Time

In recent years,because the buildings containing heating and cooling systems have been developing rapidly in our country,the heating and cooling energy consumption of buildings is rising fast. What we need to do right now is to save energy,improve energy efficiency and reduce pollution. Since the system of air through tunnel is simple, to save energy and investment, just responding to the energy development strategy of China,the prospect of air through tunnel is vast. In the past, the research of air through tunnel mainly were focused on natural or artificial tunnel and it is inevitable to ignore some factors on the effect of the air cooling in the system of air through tunnel. In orde to take full advantage of cooling in the surrounding soil of the new tunnel and get a good cooling effect, this paper attempts to explore the method which optimizes the new tunnel on the effect of the air cooling from the shape of underground tunnels and ventilation time.On the basis of analyzing the research status about the technology of air cooling in underground tunnels at home and abroad, on the basis of analyzing comprehensive impact on soil temperature, different thermo-physical parameters of different kinds of soil are listed. Then, the mathematic model of soil temperature is established, according to the known conditions. Based on the mathematic model,we can get the formula of soil temperature .According to this formula,the characteristics which is the attenuation and delay action of soil temperature are discussed. Secondly the cooling procedure that outdoor air flow through underground tunnelis analyzed. The mathe–matic model of soil temperature is established and boundary conditions, the model calculation are given .The major mission of this paper is following: mathematical model about heat transfer between air and soil is founded.And then program to simulate heat—transfer process under some certain boundary conditions. Numerical simulmion about the coupled heat transfer between airflow andtunnel is carried out with FLUENT software,and the cooling effect of underground tunnel is analyzed.In the simulation calculation, this paper give the analys is about effect of the air cooling from the shape of underground tunnels and ventilation time at two sides.and calculate air temperature under different conditions after heat exchange with soil.Finally we can draw conclusions after analyze it.Firstly, the effect of the air cooling of the same cross-sectional area of the square tube tunnels and tube tunnels is more or less the same,so we regularly use readily available pipe. The double-tube tunnel is better than single tube with the same cross-sectional area on the effect of the air cooling,which can provide about 40% cooling capacity excessively. Secondly, intermittent ventilation is better than continuous ventilation on the effect of the air cooling obviously,it is necessary to minimize ventilation time in the case of meeting the requirements of indoor temperature and humidityuse of users.In this paper, we can draw conclusions after analyzing the effect of the air cooling from the shape of underground tunnels and ventilation time,and we get the optimize design method for rural residence in North Hunan and the similar regions.For the situation that there is no specific standard to applied to guide the construction of air through tunnel,the research results in this paper can be applied to instruct the practice of the air through tunnel in the residential building for rural residence in North Hunan and the similar regions.