基于TRNSYS的岩土热响应测试及影响因素分析

Soil thermal response test and analysis of influence factors based on TRNSYS

针对实际工程中影响热响应测试的诸多因素,建立了基于地埋管储热模型的瞬时模型,模拟分析了加热功率、钻孔直径、水箱容积及回填材料对岩土热物性参数测试结果的影响。通过对同一口测试井两次不同功率、测试时长的实测,验证了该模型的准确性。研究结果表明:在设定不同的加热功率下,岩土导热系数和钻孔内传热热阻的测试结果分别相差4.94%和0.32%,而每延米换热量测试结果相差24.99%,同时验证了50 h为热响应测试的最小时长;热响应测试仪的水箱容积对导热系数的影响较小,仅影响了加热流体达到稳定状态的时间;当钻孔直径为110,130,150 mm时,随着回填材料导热系数的增大,岩土导热系数的变化率逐渐减小,整体增幅均在0.09 W/(m·K)内,表明回填材料对热响应测试影响较小。

In view of many factors influencing the thermal response test in actual engineering, establishes the instantaneous model based on the duct ground heat storage model. Simulates and analyses the influences of heating power, borehole diameter, water tank volume and backfill material on the test result of .the soil thermo-physical property. The model is verified by two practical thermal response tests for the same borehole under two different heating powers and durations. The results show that the thermal conductivity and borehole thermal resistance of these two tests are difference of 4. 94% and 0.32% respectively, but the radius heat flux per borehole unit length deviation is 24.99%. And it is also verified that the duration for thermal response test is at least 50 h. The effect of the water tank volume on the thermal conductivity can be ignored, and it just affects the time of circulating water to achieve the stability. When the diameter of borehole is 110, 130,150 mm respectively, the change rate of thermal conductivity is diminishing with the increase of the thermal conductivity of backfill materials, and the overall growth is within 0.09 W/（m · K）,which indicates that the backfill materials have a small effect on thermal response test.