The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation
New small-scale experiments are carried out to study the effect of groundwater flow on the thermal performance of water ground heat exchangers for ground source heat pump systems. Four heat exchanger configurations are investigated; single U-tube with circular cross-section (SUC), single U-tube with...
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MDPI AG
2020-03-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/13/6/1418 |
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| author | Ahmed A. Serageldin Ali Radwan Yoshitaka Sakata Takao Katsura Katsunori Nagano |
| author_facet | Ahmed A. Serageldin Ali Radwan Yoshitaka Sakata Takao Katsura Katsunori Nagano |
| author_sort | Ahmed A. Serageldin |
| collection | DOAJ |
| description | New small-scale experiments are carried out to study the effect of groundwater flow on the thermal performance of water ground heat exchangers for ground source heat pump systems. Four heat exchanger configurations are investigated; single U-tube with circular cross-section (SUC), single U-tube with an oval cross-section (SUO), single U-tube with circular cross-section and single spacer with circular cross-section (SUC + SSC) and single U-tube with an oval cross-section and single spacer with circular cross-section (SUO + SSC). The soil temperature distributions along the horizontal and vertical axis are measured and recorded simultaneously with measuring the electrical energy injected into the fluid, and the borehole wall temperature is measured as well; consequently, the borehole thermal resistance (<i>R<sub>b</sub></i>) is calculated. Moreover, two dimensional and steady-state CFD simulations are validated against the experimental measurements at the groundwater velocity of 1000 m/year with an average error of 3%. Under saturated conditions without groundwater flow effect; using a spacer with SUC decreases the <i>R<sub>b</sub></i> by 13% from 0.15 m·K/W to 0.13 m·K/W, also using a spacer with the SUO decreases the <i>R<sub>b</sub></i> by 9% from 0.11 m·K/W to 0.1 m·K/W. In addition, the oval cross-section with spacer SUO + SSC decreases the <i>R<sub>b</sub></i> by 33% compared with SUC. Under the effect of groundwater flow of 1000 m/year; <i>R<sub>b</sub></i> of the SUC, SUO, SUC + SSC and SUO + SSC cases decrease by 15.5%, 12.3%, 6.1% and 4%, respectively, compared with the saturated condition. |
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| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-13T00:32:25Z |
| publishDate | 2020-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-69ffa76d4e864c4e8f58af5a4dff50482022-12-22T03:10:27ZengMDPI AGEnergies1996-10732020-03-01136141810.3390/en13061418en13061418The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical SimulationAhmed A. Serageldin0Ali Radwan1Yoshitaka Sakata2Takao Katsura3Katsunori Nagano4Environmental System Research Laboratory, Division of Human Environmental Systems, Hokkaido University, Sapporo 060-8628, JapanEnvironmental System Research Laboratory, Division of Human Environmental Systems, Hokkaido University, Sapporo 060-8628, JapanEnvironmental System Research Laboratory, Division of Human Environmental Systems, Hokkaido University, Sapporo 060-8628, JapanEnvironmental System Research Laboratory, Division of Human Environmental Systems, Hokkaido University, Sapporo 060-8628, JapanEnvironmental System Research Laboratory, Division of Human Environmental Systems, Hokkaido University, Sapporo 060-8628, JapanNew small-scale experiments are carried out to study the effect of groundwater flow on the thermal performance of water ground heat exchangers for ground source heat pump systems. Four heat exchanger configurations are investigated; single U-tube with circular cross-section (SUC), single U-tube with an oval cross-section (SUO), single U-tube with circular cross-section and single spacer with circular cross-section (SUC + SSC) and single U-tube with an oval cross-section and single spacer with circular cross-section (SUO + SSC). The soil temperature distributions along the horizontal and vertical axis are measured and recorded simultaneously with measuring the electrical energy injected into the fluid, and the borehole wall temperature is measured as well; consequently, the borehole thermal resistance (<i>R<sub>b</sub></i>) is calculated. Moreover, two dimensional and steady-state CFD simulations are validated against the experimental measurements at the groundwater velocity of 1000 m/year with an average error of 3%. Under saturated conditions without groundwater flow effect; using a spacer with SUC decreases the <i>R<sub>b</sub></i> by 13% from 0.15 m·K/W to 0.13 m·K/W, also using a spacer with the SUO decreases the <i>R<sub>b</sub></i> by 9% from 0.11 m·K/W to 0.1 m·K/W. In addition, the oval cross-section with spacer SUO + SSC decreases the <i>R<sub>b</sub></i> by 33% compared with SUC. Under the effect of groundwater flow of 1000 m/year; <i>R<sub>b</sub></i> of the SUC, SUO, SUC + SSC and SUO + SSC cases decrease by 15.5%, 12.3%, 6.1% and 4%, respectively, compared with the saturated condition.https://www.mdpi.com/1996-1073/13/6/1418ground source heat pumpoval cross-sectiongroundwaterborehole heat exchangercfdsandtank |
| spellingShingle | Ahmed A. Serageldin Ali Radwan Yoshitaka Sakata Takao Katsura Katsunori Nagano The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation Energies ground source heat pump oval cross-section groundwater borehole heat exchanger cfd sandtank |
| title | The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation |
| title_full | The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation |
| title_fullStr | The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation |
| title_full_unstemmed | The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation |
| title_short | The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation |
| title_sort | effect of groundwater flow on the thermal performance of a novel borehole heat exchanger for ground source heat pump systems small scale experiments and numerical simulation |
| topic | ground source heat pump oval cross-section groundwater borehole heat exchanger cfd sandtank |
| url | https://www.mdpi.com/1996-1073/13/6/1418 |
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