Research On The Application Of The Earth-to-air Heat Exchanger

The Earth-to-Air Heat Exchanger (EAHE) system can cool or heat the outdoor airby using cold and heat accumulated in the earth of the shallow surface of theground.The EAHE system can cool and heat buildings and reduce the cooling load ofthe fresh air in the HVAC system in summer and the heating load of the fresh air inwinter. This system is simple and can reduce operating consumption. Therefore, theEAHE system is an application technology of renewable sources of energy and can bewidely used.The research object in this paper is the buried pipes system of the EAHE system.The research purpose is to complete the design of the system in the Zhi Gate of theHan Chang’an City Site in Xi’an of Shan’xi province. The paper sums up thecalculating method of collapsible loess’ thermophysical properties and the formula ofsoil temperature.This paper also discusses the attenuation and delay of soil temperaturewave.Through the analysis of the heat transfer process between the air in the buriedpipes and the soil, the paper establishes the formula for computing the parameters’change while air flows in the buried pipes of the EAHE system. Based on thecomputation model of the EAHE system, this paper studies the impact of the differentparameters on the heat exchange process of the EAHE system. The varying parametersinclude physical parameters of the soil, the time of the ventilation and the runningmode, pipe length, depth of the buried pipes, velocity of the air in the system, pipe radius, and the temperature of the inlet air. In addition, this paper analyzes thefeasibility of applying the EAHE systems in China. The results of all my researchesprovide references for real projects that apply the EAHE system.Based on the theoretical study, the weather condition of Xi’an and the temperaturedistribution characteristics of the soil, the EAHE system for Zhi Gate of the HanChang’an City Site in Xi’an of Shanxi province is designed. Then, the design methodsof the EAHE system application in the buildings are given from the perspective of thedesign conditions, the system plan and the design calculation. In the end, this paperdiscusses the economy of the EAHE system from the perspective of initial investment,operating cost by using the design data and quota of budget of the Zhi Gate.