Heat Transfer and Energy Diffusion Analysis of Cannula Ground Heat Exchanger

A heat transfer model about fluid flow and heat conduct in cannula ground heat exchanger were given in this article. The heat transfer characteristics were analyzed by means of numerical method of finite element. Affect of difference size of buried tubes and the velocity of flow in the tube, on fluid outlet temperature and unit heat transfer of burned pipe were discussed. Startup time is about 8 hours of for cannula ground heat exchanger. Small size of burned pipes need a few longer startup time than big size. But big size cannula heat exchanger can save energy in the ground better.