Numerical study on the effect of U-shaped deep-buried pipe type on heat transfer performance

Abstract

In combination with a U-shaped deep-buried drilling project for heating buildings in Xi’an, three-dimensional (3D) full-size numerical calculation models with a depth of 1000 m were established for coupling the internal and external heat transfer of U-shaped and W-shaped pipes. This is based on the measured well temperature data of a drilling project and lithology of rock and soil obtained from the tests. Furthermore, by calculating and comparing the total heat transfer quantity and heat transfer per linear meter between two types of buried pipes during the simulation, the heat transfer effect of W-shaped buried pipe versus U-shaped buried pipe was analyzed. The simulation results show that under the same flow rate and inlet water temperature of buried pipe, there is no significant difference in heat transfer per linear meter between W-shaped and U-shaped buried pipes. Considering the outlet pipe diameter of W-shaped buried pipe, the flow rate of its inlet pipe and the spacing between buried pipes can be enhanced or enlarged in practical projects. It can be concluded that W-shaped buried pipe has a better heat transfer effect than U-shaped buried pipe under certain conditions. Therefore, similar solutions can be considered to increase the heat transfer capacity of deep-buried pipes in limited space sites for practical projects, and then the building heating area can also be expanded.