scholarly journals Small-Scale Experimental Model of a Helical Steel Pile as the Heat Exchanger in Ground Source Heat Pumps

2020 ◽  
Author(s):  
Leya Kober ◽  
Sarah Nicholson ◽  
Sylvie Antoun ◽  
Seth Dworkin
Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5471
Author(s):  
Peng Li ◽  
Peng Guan ◽  
Jun Zheng ◽  
Bin Dou ◽  
Hong Tian ◽  
...  

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.


Author(s):  
Hakan Demir ◽  
Ş. Özgür Atayılmaz ◽  
Özden Agra ◽  
Ahmet Selim Dalkılıç

The earth is an energy resource which has more suitable and stable temperatures than air. Ground Source Heat Pumps (GSHPs) were developed to use ground energy for residential heating. The most important part of a GSHP is the Ground Heat Exchanger (GHE) that consists of pipes buried in the soil and is used for transferring heat between the soil and the heat exchanger of the GSHP. Soil composition, density, moisture and burial depth of pipes affect the size of a GHE. Design of GSHP systems in different regions of US and Europe is performed using data from an experimental model. However, there are many more techniques including some complex calculations for sizing GHEs. An experimental study was carried out to investigate heat transfer in soil. A three-layer network is used for predicting heat transfer from a buried pipe. Measured fluid inlet temperatures were used in the artificial neural network model and the fluid outlet temperatures were obtained. The number of the neurons in the hidden layer was determined by a trial and error process together with cross-validation of the experimental data taken from literature evaluating the performance of the network and standard sensitivity analysis. Also, the results of the trained network were compared with the numerical study.


Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4527
Author(s):  
Hao Liu ◽  
Hongyi Zhang ◽  
Saqib Javed

Recent data suggest that heat pumps, despite having the potential to cover over 90% of the global space and water heating demands, only provide less than 5% of global heating. Heat pumps, in general, and ground source heat pumps, specifically, offer significant potential for energy savings and carbon emissions reduction in buildings. The realization of these potential benefits, however, requires proper design, installation, and operation of the entire heat pump system. This paper presents the performance analysis of a Swedish ground source heat pump system providing space heating and hot water to a sports clubhouse. The installation has been carefully instrumented to enable full characterization of the whole system including auxiliary components such as circulation pumps and supplementary heating. Seasonal performance factors, calculated for monthly and annual periods using high-quality, high-resolution measurement data collected over three years of system operation, have been reported based on the SEPEMO (SEasonal PErformance factor and MOnitoring for heat pump systems) and Annex 52 boundary schemes for evaluating and benchmarking the performance of the ground source heat pump system. The auxiliary system components were shown to have a large impact on the overall performance of the system. In particular, the legionella protection system was found to affect performance considerably. Recommendations as to how to improve the performance of the system under study and other similar systems are made from the design, installation, and operation perspectives.


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