The Exploration on Heat Transfer Models for Borehole Heat Exchanger in the Soil with Groundwater Advection

2013 ◽  
pp. 705-712
Author(s):  
Lei Zhao ◽  
Linlin Zhang ◽  
Songtao Hu
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Borehole Heat Exchanger ◽  
Transfer Models

scholarly journals Study on the Coupled Heat Transfer Model Based on Groundwater Advection and Axial Heat Conduction for the Double U-Tube Vertical Borehole Heat Exchanger

2020 ◽  
Vol 12 (18) ◽  
pp. 7345
Author(s):  
Linlin Zhang ◽  
Zhonghua Shi ◽  
Tianhao Yuan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Borehole Heat Exchanger ◽  
Coupled Heat Transfer ◽  
Advection Velocity

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.

Development of an efficient numerical model and analysis of heat transfer performance for borehole heat exchanger

2020 ◽  
Vol 152 ◽  
pp. 189-197 ◽  
Author(s):  
Xiaohui Yu ◽  
Hongwei Li ◽  
Sheng Yao ◽  
Vilhjalmur Nielsen ◽  
Alfred Heller
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Borehole Heat Exchanger

Thermal Performance of a Borehole Heat Exchanger Located in Guayaquil-Ecuador Using Novel Heat Transfer Fluids

2015 ◽  
Author(s):  
Guillermo Soriano ◽  
Diego Siguenza
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Three Dimensional ◽  
Borehole Heat Exchanger ◽  
Element Analysis ◽  
Heat Transfer Fluids ◽  
Ground Source ◽  
Microencapsulated Phase Change Materials

An analysis of thermal performance of a vertical Borehole Heat Exchanger (BHE) from a close loop Ground Source Heat Pump (GSHP) located in Guayaquil-Ecuador is presented. The project aims to assess the influence of using novels heat transfer fluids such as nanofluids, slurries with microencapsulated phase change materials and a mixture of both. The BHEs sensitive evaluation is performed by a mathematical model in a finite element analysis by using computational tools; where, the piping array is studied in one dimension scenario meanwhile its surroundings grout and ground volumes are presented as a three dimensional scheme. Therefore, an optimized model design can be achieved which would allow to study the feasibility of GSHP in buildings and industries in Guayaquil-Ecuador.

scholarly journals Field Test and Numerical Simulation on Heat Transfer Performance of Coaxial Borehole Heat Exchanger

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5471
Author(s):  
Peng Li ◽  
Peng Guan ◽  
Jun Zheng ◽  
Bin Dou ◽  
Hong Tian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Thermal Response ◽  
Heat Pumps ◽  
Inlet Temperature ◽  
Borehole Heat Exchanger ◽  
Ground Source Heat Pumps ◽  
Ground Source

Ground thermal properties are the design basis of ground source heat pumps (GSHP). However, effective ground thermal properties cannot be obtained through the traditional thermal response test (TRT) method when it is used in the coaxial borehole heat exchanger (CBHE). In this paper, an improved TRT (ITRT) method for CBHE is proposed, and the field ITRT, based on the actual project, is carried out. The high accuracy of the new method is verified by laboratory experiments. Based on the results of the ITRT and laboratory experiment, the 3D numerical model for CBHE is established, in which the flow directions, sensitivity analysis of heat transfer characteristics, and optimization of circulation flow rate are studied, respectively. The results show that CBHE should adopt the anulus-in direction under the cooling condition, and the center-in direction under the heating condition. The influence of inlet temperature and flow rate on heat transfer rate is more significant than that of the backfill grout material, thermal conductivity of the inner pipe, and borehole depth. The circulating flow rate of CBHE between 0.3 m/s and 0.4 m/s can lead to better performance for the system.

Research on heat transfer characteristics and typical parameters sensitivity analysis of the deep borehole heat exchanger combined with the geothermal wells

2021 ◽  
pp. 1-25
Author(s):  
Jiuchen Ma ◽  
Qiuli Zhang ◽  
Feiyu Yi ◽  
Qian Jiang ◽  
Yacheng Xie ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Sensitivity Analysis ◽  
Heat Exchanger ◽  
Geothermal Water ◽  
Deep Borehole ◽  
Borehole Heat Exchanger ◽  
Heat Transfer Characteristics ◽  
Geothermal Wells ◽  
Heat Transfer Capacity ◽  
Water Exploitation

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.

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