Study On Heat Transfer Calculation Of Ground Heat Exchanger And Its System Design And Operation Method

In recent years, energy conservation and environmental protection has become the theme of social development because of the haze brought great impact to the people's production, life and health. Building energy consumption has accounted for nearly one-third of the construction industry in China's energy consumption industry, so energy saving is imminent, which air conditioning, heating energy are primary, therefore,how to reduce air conditioning and heating energy is HVAC research personnel has been studying the subject. As an efficient, energy efficient,environmentally friendly air conditioning system, ground source heat pump system has been rapid development and application in china, which research that focused on buried tube ground source heat pump system underground heat transfer model and system simulation research has been more than 30 years, however, in the project so far there are some problems have not been solved.In this paper, we base on the heat transfer model of the existing buried heat exchanger to simply the calculation model of the thermal resistance in the borehole, and according to the finite length of the heat source model,we obtain the average temperature and the fluid outlet temperature of the buried heat exchanger; the PDEtool provided by MATLAB is used to simulate the underground heat transfer of the underground heat exchanger,which is compared with the results that is calculated by the finite length of the heat exchanger, we find that the simulation results are in good agreement with the calculated results; we use the engineering design parameters and operating parameters of the ground source heat pump system of the office building to verify the results of the simplified heat transfer model, and find that the results are in good agreement with each other, which can meet the requirements of engineering applicationBased on the simplified heat transfer model, this paper study the influence factors of the ground source heat pump system. The main contents are as follows:(1) This paper study the influence of drilling distance, drilling depth and internal combustion flow on the heat transfer of ground heat exchanger,which provides a theoretical reference for the selection of buried pipe design parameters.(2) We study the changes of the pipe heat exchanger fluid average temperature by calculated the results under the continuous operation condition and the different starting and stopping ratio 2: 1,1 : 1,1: 2 three kinds of intermittent operating conditions;(3) It is proposed to design and partition the ground heat exchanger according to the characteristics of the building load. By comparing the actual operation result and the partitioned operation result of an office building in Taian, it is concluded that the partition design and operation are more favorable efficient operation of the system.