scholarly journals Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1270 ◽  
Author(s):  
Cristina Sáez Blázquez ◽  
Laura Piedelobo ◽  
Jesús Fernández-Hernández ◽  
Ignacio Martín Nieto ◽  
Arturo Farfán Martín ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Borehole Heat Exchanger ◽  
Physical Processes ◽  
Geothermal Resources ◽  
Thermal Exchange ◽  
Heating And Cooling ◽  
Ground Source ◽  
Grouting Material ◽  
Polyethylene Container

Ground source heat pump (GSHP) systems are becoming popular in space heating and cooling applications. Despite this fact, in most countries, the role of this energy is not as important as it should be nowadays according to its capabilities for energy generation without CO2 emissions, mainly due to the lack of technical knowledge about GSHP performance. The analysis of the physical processes that take part in the geothermal exchanges is necessary to allow the optimal exploitation of the geothermal resources. For all the above, an experimental geothermal device was built in the laboratory to control the phenomena that take place in a borehole heat exchanger (BHE). A 1-m high single-U heat exchanger was inserted in the center of a polyethylene container which also included granular material (surrounding ground) and the grouting material. Temperature sensors were situated in different positions of the experimental setup. Physical processes are evaluated to finally validate the model. Numerous applications can be developed from the experimental BHE. In this research, the determination of the thermal conductivity of the material used as medium was carried out. Results of this parameter were also compared with the ones obtained from the use of the KD2 Pro device.

scholarly journals A Novel Analytical-ANN Hybrid Model for Borehole Heat Exchanger

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6213
Author(s):  
Anjan Rao Puttige ◽  
Staffan Andersson ◽  
Ronny Östin ◽  
Thomas Olofsson
Keyword(s):  
Neural Network ◽  
Heat Exchanger ◽  
Analytical Model ◽  
Hybrid Model ◽  
Time Resolution ◽  
Network Models ◽  
Borehole Heat Exchanger ◽  
Neural Network Models ◽  
Ground Source

Optimizing the operation of ground source heat pumps requires simulation of both short-term and long-term response of the borehole heat exchanger. However, the current physical and neural network based models are not suited to handle the large range of time scales, especially for large borehole fields. In this study, we present a hybrid model for long-term simulation of BHE with high resolution in time. The model uses an analytical model with low time resolution to guide an artificial neural network model with high time resolution. We trained, tuned, and tested the hybrid model using measured data from a ground source heat pump in real operation. The performance of the hybrid model is compared with an analytical model, a calibrated analytical model, and three different types of neural network models. The hybrid model has a relative RMSE of 6% for the testing period compared to 22%, 14%, and 12% respectively for the analytical model, the calibrated analytical model, and the best of the three investigated neural network models. The hybrid model also has a reasonable computational time and was also found to be robust with regard to the model parameters used by the analytical model.

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.

Research of Combined Heating and Cooling by Solar Ground-Source Heat Pump and PCM Thermal Storage

Solar Energy ◽  
2005 ◽  
Author(s):  
Li-Xia Wu ◽  
Mao-Yu Zheng
Keyword(s):  
Heat Exchanger ◽  
Solar Energy ◽  
Cooling System ◽  
Storage System ◽  
Thermal Storage ◽  
Cold Climate ◽  
Coefficient Of Performance ◽  
Tube Heat Exchanger ◽  
Heating And Cooling ◽  
Ground Source

In severely cold climate, significant amount of energy is used to heat buildings. Both the theoretical computation and experiments show that it is difficult and uneconomical to use solar energy collected merely in winter. A new method has been developed to store solar energy during summer, fall, and spring for winter heating. This paper presents in details the combined heating and cooling system by solar ground-source heat pump (GSHP) and short-term phase change material (PCM) thermal storage. The hybrid system and season-shift mode can make the sustainable use of solar energy possible. As for the above system, the solar energy collected is stored into soil through the U-tube heat exchanger. In winter, the thermal energy is taken out for heating using the GSHP. At the end of the heat supply season, the underground soil temperature may drop below 0°C. Then some heat exchangers begin to store the heat into soil while others stop. In summer, the U-tube heat exchanger is used to produce low temperature water without compressor to cool the room. The project was supported by the Energy Conservation Laboratory at Harbin Institute of Technology (HIT). The whole systems, which have run for over two years, consist of a flat plate solar hot water system installed on the roof, a soil thermal storage system, a GSHP system, a PCM thermal storage system and heating-cooling system. The measured results show an average heating coefficient of performance (COP) of 3.2 in winter and the cooling coefficient of performance (COP) of 18.0 in summer. The PCM thermal storage system has been investigated by numerical simulation and experiments in the cold climate. In most time of winter, the PCM thermal storage system was used to supply heat, while solar GSHP was also used during continuous cloudy days and severely cold days. The result shows that above method is feasible. The most advantage of this system is that it does not need the usual energy equipment. The numerical analysis has been used to investigate the thermal energy balance of the underground soil. The variation of the soil temperature field around the U-tube heat exchanger has also been studied, not only for the single exchanger but also for multiple exchangers. The underground soil makes the yearly thermal balance possible because the solar energy supplies the heat that is extracted from the soil for heating in winter. Then this system can operate for a long period.

scholarly journals Numerical Investigation of the Physical Properties Effect on the Thermal Performance of a Vertical Geothermal Heat Exchanger

2018 ◽  
Vol 8 (2) ◽  
pp. 2715-2723
Author(s):  
M. Benyoub ◽  
B. Aour ◽  
B. Bouhacina ◽  
K. Sadek
Keyword(s):  
Heat Exchanger ◽  
Construction Materials ◽  
Green Energy ◽  
Filling Material ◽  
Geothermal Heat ◽  
Thermal Exchange ◽  
Heating And Cooling ◽  
Knowing That ◽  
Shaped Tube ◽  
Geothermal Heat Exchanger

Low-temperature geothermal energy is a promising technique for heating and cooling residential and commercial premises, especially since it is one of the green energy solutions that respect the environment. The principle of this technique is based on thermal exchange between the heat pump and the basement using a vertically buried heat exchanger. This is usually made of a U-shaped tube inserted vertically in a borehole made in the ground and filled with a filler material. The purpose of the present study is to vary the different construction materials of the U-tube, the filling material and the soil, in order to obtain the most energy-efficient parameters. The evolution of temperature and heat flux as a function of time has been highlighted for different combinations. Knowing that an experimental study requires a considerable monetary fund, the present model has been validated using previously literature results. Recommendations on the choice of different materials of the geothermal heat exchanger are proclaimed at the end of this work.

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