A semi-analytical heat transfer model for deep borehole heat exchanger considering groundwater seepage

2022 ◽  
Vol 175 ◽  
pp. 107465
Changlong Wang ◽  
Xin Wang ◽  
Jinli Lu ◽  
Yuehong Lu ◽  
Yanhong Sun ◽  
2020 ◽  
Vol 12 (18) ◽  
pp. 7345
Linlin Zhang ◽  
Zhonghua Shi ◽  
Tianhao Yuan

In this paper, a dynamic heat transfer model for the vertical double U-tube borehole heat exchanger (BHE) was developed to comprehensively address the coupled heat transfer between the in-tube fluid and the soil with groundwater advection. A new concept of the heat transfer effectiveness was also proposed to evaluate the BHE heat exchange performance together with the index of the heat transfer rate. The moving finite line heat source model was selected for heat transfer outside the borehole and the steady-state model for inside the borehole. The data obtained in an on-site thermal response test were used to validate the physical model of the BHE. Then, the effects of soil type, groundwater advection velocity, inlet water flow rate, and temperature on the outlet water temperature of BHE were explored. Results show that ignoring the effects of groundwater advection in sand gravel may lead to deviation in the heat transfer rate of up to 38.9% of the ground loop design. The groundwater advection fosters the heat transfer of BHE. An increase in advection velocity may also help to shorten the time which takes the surrounding soil to reach a stable temperature. The mass flow rate of the inlet water to the BHE should be more than 0.5 kg·s−1 but should not exceed a certain upper limit under the practical engineering applications with common scale BHE. The efficiency of the heat transfer of the double U-tube BHE was determined jointly by factors such as the soil’s physical properties and the groundwater advection velocity.

2013 ◽  
Vol 65 ◽  
pp. 231-241 ◽  
Pingfang Hu ◽  
Zhongyi Yu ◽  
Na Zhu ◽  
Fei Lei ◽  
Xudong Yuan

2006 ◽  
Vol 27 (8) ◽  
pp. 31-38 ◽  
Alberto Cavallini ◽  
Davide Del Col ◽  
Luca Doretti ◽  
Marko Matkovic ◽  
Luisa Rossetto ◽  

Jiuchen Ma ◽  
Qiuli Zhang ◽  
Feiyu Yi ◽  
Qian Jiang ◽  
Yacheng Xie ◽  

Abstract Based on abundant hydrothermal geothermal resources at the depth of 1000-2000m formation in the basin of the BoHai Bay, the deep borehole heat exchanger (DBHE) combined with the geothermal wells is proposed. According to the modified thermal resistance and capacity model (MTRCM), the heat transfer models inside and outside borehole are established. The transient analytical solutions are obtained by applying Laplace transform method to calculate the vertical temperature profiles in the inlet (outlet) pipe and the grout of the DBHE. The mathematical model and the analytical solutions are validated by the experimental data and existing studied data. This paper utilizes respectively the Matlab2012 and the Feflow7.1 to solve the heat transfer models inside and outside the DBHE. The sensitivity analysis is performed to examine the influence of typical parameters on the DBHE heat transfer characteristics. Under the well distance of 50m, the DBHE heat transfer capacity increases by 29.5% and 42.5% when the quantity of geothermal water exploitation increases from 0m3/h to 75m3/h and 150m3/h respectively. The results show that the heat transfer mechanism is changed in the thermal reservoir, and the heat transfer progress of the DBHE is intensified through orderly regulating the quantity of geothermal water exploitation and the well distance. However, with the change of the quantity of geothermal water exploitation, the growth rate of the DBHE heat transfer capacity reduces and the sensitivity of the change of the typical parameters on the DBHE heat transfer performance reduces.

2016 ◽  
R. E. Mironov ◽  
Yu. I. Shtern ◽  
M. Yu. Shtern ◽  
M. S. Rogachev

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