A simulation design method for the spacing between boreholes based on the representative temperature of the borehole wall

Abstract

The invention discloses a hole wall representation temperature based simulation design method for drill hole space and belongs to the field of drill hole space design in the geothermal technology. The simulation design method is characterized in that the method comprises arbitrarily selecting four adjacent drill holes with perpendicular U-shaped buried pipes arranged inside from a drill hole group to form a four-drill-hole region, which is also called a unit drill hole group region; dividing the region into two double-drill-hole sub-regions from a horizontal direction, calculating a general formula for a transient temperature of a point M1 under a cylindrical coordinate system of the double-drill-hole sub-regions; mapping the point M1 transversely onto a vertically contacted virtual line heat source or actual line heat source to obtain the hole wall representation temperature Tb1 under the double drill holes; calculating the hole wall representation temperature Tb2 by transverse mapping of middle point M2 in the four-drill-hole region onto the virtual line heat source or the actual line heat source in the same way; setting thresholds of hole wall representation temperature change rates P1 and P2 of the double-drill-hole sub-regions and the four-drill-hole region as P1MAX and P2MAX successively; and calculating L1OPT and L2OPT in a threshold range successively through multiple times of iteration to obtain an optimal value of the drill hole space. According to the simulation design method, contradictions between the drill hole space and the heat exchanging efficiency are solved, the problem of slow calculation speed is solved under the condition that the accuracy is guaranteed, and the drill hole space and the hole wall representation temperature are balanced.

Description

technical field [0001] Ground source heat pump technology is an efficient, energy-saving and environmentally friendly energy utilization method, which can realize the transfer of heat from low-level heat sources to high-level heat sources by consuming a small amount of high-grade energy. In recent years, with the strong support of the Chinese government, the number of ground source heat pump projects has been increasing year by year, but its key technologies and related theories still need to be improved and perfected. [0002] The ground source heat exchanger is the underground heat exchange device of the ground source heat pump system. It usually consists of a set of regularly arranged boreholes and vertical U-shaped buried pipes. The heat exchange efficiency of the ground source heat exchanger directly affects the operating efficiency of the ground source heat pump system, so its size design is an essential link before building the entire system. However, in order to save ...

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Problems solved by technology

Although this modeling method can accurately solve the representative temperature of the hole wall, the calculation speed is slow, and it is impossible to directly analyze the influence of the hole spacing on the heat transfer process

Both in the solution of the hole wall temperature and the design of the ground source heat exchanger have great limitations

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