Evolution mechanism of temperature field of the frozen wall of the vertical shaft under cold energy extraction.

To verify the feasibility of extracting the excess cold energy of the frozen wall and clarify the variation mechanism of the frozen wall temperature field during the cold energy extraction process, this study carried out the field extraction experiment of the excess cold energy of the frozen wall in the central air shaft of Linhuan Coal Mine. The results showed that the maximum temperature difference of salt liquid before and after cold extraction was 19.9°C. The extraction effect of the frozen wall cold energy was very significant. Through numerical simulation, this study reproduced the whole process of cold energy extraction of the frozen wall, and find that on the 30th day of cold energy extraction, the average temperature increase of the frozen wall under the scheme of main row hole plus auxiliary hole cold energy extraction is 2.2 times that of only main row hole cold energy extraction. The main surface temperature of the frozen wall shows a "wavy" distribution, and the lowest point is in the central area of the frozen wall. The main surface temperature rises with the increase of cold energy extraction time. And on the 30th day of cold energy extraction, the temperature in the east, south, west, and north of the frozen wall increased by 5.8°C, 12.5°C, 8.5°C, 11.1°C, respectively. Meanwhile, it is found that the higher the salt temperature, the higher the thermal conductivity of the frozen wall, and the faster the average temperature increases. [ABSTRACT FROM AUTHOR]