Research Of Tunnel Wind Heat Exchange Performance Effect Factors

Building energy consumption is energy consumption of building use,including heating,air conditioning,hot water supply,cooking,household appliances and so on.Among them,mostly are building heating and air-conditioning energy consumption.With the improvement of people's quality of life,heating and air conditioning building increased rapidly,led to a sharp increase in our energy consumption of heating and air conditioning.Therefore,to improve the energy efficiency,energy-saving and emission-reduction has become the today's topic.Wind tunnel technology is a new building energy-saving technology,which is air flowing through the tunnel and heat exchange with soil around the tunnel to achieve cooling and heating purposes.Because its simple system,low running costs,saving energy and investment and responds to the country's energy development strategy,it has a great potential for future application.The paper expatiates thermophysical properties parameters of soil and the calculation formula of the soil temperature distribution,and analyzes the characteristics of the soil temperature change which are temperature wave attenuation and time delay of soil temperature field.Using psychrometric chart to explain heat transfer principles of air and soil in wind tunnel system,this paper establishes two three-dimensional mathematical models for continuous operation and intermittent operation to simulate air movement inside the tunnel and heat exchange of air and soil.The paper uses the modeling software ICEM to establish physical model and mesh,the numerical simulation software FLUENT to caculate,and illustrates the model boundary conditions and other related Settings.In addition,the paper analyzes the outdoor climatic conditions in Chongqing.Summer hot,winter cold and wet.In summer,Outdoor air dew point temperature mostly lower than that of soil temperature,soil is a good natural cold source.In winter,Outdoor air temperature also mostly lower than the soil original temperature.This shows that wind tunnel technology is an ideal fresh air handling modes whether in winter or summer in Chongqing.The main contents of this paper is the influence of various factors to the wind tunnel heat transfer systems.These factors include buried pipe length,pipe diameter,depth of buried pipe,wind velocity,inlet air temperature,operation mode and buried tube spacing.Finally,the paper analyzes cooling process of the hottest summer day and heating process of most cold winter.We can conclude that the heat transfer effect of intermittent operation is better than continuous operation,and if the intermittent operation time is shorter,then the soil recovery time is longer,and better heat transfer effect.Therefore,as far as possible to reduce ventilation time in the case of meet indoor temperature requirements.Wind tunnel system for extreme weather conditions which include hottest summer day and the most cold winter have a relatively remarkable cooling and warming effect.Due to the lack of concrete tunnel ventilation system design specifications,This paper analyzes influence of operation mode and varies factors.The conclusion could provide some reference for desigining tunnel ventilation system in practical engineering.