TEST METHOD RESEARCH OF SOIL THERMAL CONDUCTIVITY OF GROUND SOURCE HEAT PUMP BASED ON THREE-DIMENSIONAL DISTRIBUTED THERMAL RESPONSE TEST HEAT TRANSFER MODEL

Deng Zhenpeng; Nian Yongle; Cheng Wenlong

doi:10.19912/j.0254-0096.tynxb.2021-1471

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Acta Energiae Solaris Sinica ›› 2023, Vol. 44 ›› Issue (4) : 259-265. DOI: 10.19912/j.0254-0096.tynxb.2021-1471

TEST METHOD RESEARCH OF SOIL THERMAL CONDUCTIVITY OF GROUND SOURCE HEAT PUMP BASED ON THREE-DIMENSIONAL DISTRIBUTED THERMAL RESPONSE TEST HEAT TRANSFER MODEL

Deng Zhenpeng, Nian Yongle, Cheng Wenlong

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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.

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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Deng Zhenpeng, Nian Yongle, Cheng Wenlong. TEST METHOD RESEARCH OF SOIL THERMAL CONDUCTIVITY OF GROUND SOURCE HEAT PUMP BASED ON THREE-DIMENSIONAL DISTRIBUTED THERMAL RESPONSE TEST HEAT TRANSFER MODEL[J]. Acta Energiae Solaris Sinica. 2023, 44(4): 259-265 https://doi.org/10.19912/j.0254-0096.tynxb.2021-1471

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