地质参数对中深层地热井长期取热特性影响分析

EFFECTS OF GEOLOGICAL PARAMETERS ON LONG-TERM THERMAL EXTRACTION CHARACTERISTICS OF MEDIUM-DEEP GEOTHERMAL WELL

基于中深层地热井换热原理,数值分析不同地质参数下中深层地热井在长期运行过程中单井取热量、能效系数、热泵机组COP以及岩土温度的变化情况。研究结果表明:岩土导热系数对长期运行期间的单井取热量、能效系数的下降比例影响较大,且岩土导热系数越小其下降比例越大。岩土导热系数为2.0 W/(m·K)时,第30年的单井取热量、能效系数与第1年相比均下降13.7%。地温梯度对长期运行期间的热泵机组COP的下降程度有较大影响,其下降比例随地温梯度的增大而增大。此外,不同地质参数下岩土温度影响半径随运行年份增加的比例一致。

Based on the heat transfer mechanism of medium-deep geothermal well,numerical analysis is carried out to investigate the effects of different geological parameters on the single-well heat extraction load(HEL),energy efficiency coefficient,heat pump unit COP,and rock-soil temperature during the long-term operation. The results indicate that rock-soil thermal conductivity(RTC)has a significant effect on the decline ratios of single-well HEL and energy efficiency coefficient with operating year. The lower RTC,the larger decline ratios. At 2.0 W/(m·K)of RTC,both single-well HEL and energy efficiency coefficient in the 30 th year decline by13.7% compared to those in the first year. Geothermal temperature gradient largely affects the decline degree of heat pump unit COP with operating year. The decline ratio increases with an increasing geothermal temperature gradient. Additionally,under different geological parameters,the influence radius of rock and soil temperature increases proportionally with operating years.