为进一步提升土壤热导率测试精度和效率,基于建立的三维分布式热响应测试（DTRT）理论模型,结合粒子群算法提出一种新型土壤热导率的DTRT测试方法,并基于该方法对土壤热导率的时空变化规律进行研究。首先针对U型埋管换热器建立DTRT三维传热分析模型,然后通过建立DTRT实验平台获得流体温度数据并验证建立的传热模型,同时利用建立的模型计算分析土壤热导率、管间距和加热功率对流体温度的影响,最后基于不同时间和深度的温度数据并采用粒子群算法对土壤热导率随时间变化和空间分布规律进行研究。研究结果表明,建立的DTRT理论模型具有较高精度,流体进出口温度的平均分析误差约为0.5 ℃;利用不同深度的温度数据预测出的土壤热导率稳定性较好,最大偏差仅为1.49%;不同时间土壤热导率的预测结果收敛性也较好,在5和20 h下的测试结果偏差仅为4.67%。此外,土壤热导率预测结果与参考值吻合度较高,说明该文提出的方法可在短时间内对不同深度的土壤热导率进行有效预测。
Abstract
Soil thermal conductivity is a key parameter for ground source heat pump systems design, for improving the accuracy and efficiency of soil thermal conductivity testing, this paper proposes a new estimation method for soil thermal conductivity based on the built three-dimensional theoretical model of distributed thermal response test （DTRT） and particle swarm algorithm, and the temporal and spatial variation of soil thermal conductivity is studied by the proposed method. Firstly, a three-dimensional heat transfer model for DTRT of U-pipe borehole heat exchanger is established, and then a DTRT experimental platform is built to obtain the fluid temperature profiles and validate the established heat transfer model. At the same time, the effects of soil thermal conductivity, pipe spacing and heating power on fluid temperature are investigated by the established model. Finally, the variation of soil thermal conductivity with time and depth is estimated by using particle swarm algorithm based on DTRT data. The results show that the established DTRT theoretical model has high accuracy, and the average analysis error of fluid inlet and outlet temperature is about 0.5 ℃. And the estimated soil thermal conductivity at different depths is stable, and the maximum deviation is only 1.49%. In addition, the predicted soil thermal conductivity at different times also has good convergence, and the deviation between 5 h and 20 h is only 4.67%. Simultaneously, the predicted soil thermal conductivity is in good agreement with the reference value, indicating that the proposed method in this paper can predict soil thermal conductivity at different depths in a short time effectively.
关键词
地源热泵 /
土壤热导率 /
DTRT /
U型埋管换热器 /
三维传热模型 /
粒子群
Key words
ground source heat pump /
soil thermal conductivity /
DTRT /
U-pipe borehole heat exchanger /
three-dimensional heat transfer model /
particle swarm optimization
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基金
国家自然科学基金（52006211）; 安徽省重点研究与开发计划（202004a07020053）
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