Field test on energy performance of medium-depth geothermal heat pump systems (MD-GHPs)

Deng, Jiewen; Wei, Qingpeng; Liang, Muxuan; He, Suqin; Zhang, Hui

doi:10.1016/j.enbuild.2018.12.006

Cited by 80 publications

(27 citation statements)

References 28 publications

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“…During the operation, ground-side water is pumped down to the DBHE through the outer pipe, extracting heat from ground. Then it flows upward through the inner pipe, meanwhile the heat is transferred to water in the outer pipe since the thermal resistance of the inner pipe is not high enough [13].…”

Section: System Descriptionmentioning

confidence: 99%

“…In order to optimize the system design and control strategies of DBHEs, the influence factors of heat transfer performance should be analyzed and studied. As shown in Figure 12, the influence factors could be classified into 3 categories: (1) External factors for the geothermal properties, including thermal conductivity of ground and geothermal gradient;( 2) Internal factors for the DBHEs, including the thermal property and depth of DBHEs; (3) Synergic adjustment for operation during the heating season, including the adjustment of inlet water temperature and flow rate, which are field tested to be key factor influencing the heat transfer performance of DBHEs [13].…”

Section: Analysis On the Influence Factors Of Heat Transfer Performancementioning

confidence: 99%

“…Besides, this method was successfully used as heat source in a university in Germany [12]. Recently, this method was applied for space heating with heat pump systems in China and field test was conducted in previous study [13]. Results showed that the outlet water temperature from DBHEs with depth of 2500 m could reach 34.7 °C with heat extraction of 273 kW per DBHE, which provides a stable and high-temperature heat source for heat pump systems.…”

Section: Introductionmentioning

confidence: 97%

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Simulation Analysis on the Heat Performance of Deep Borehole Heat Exchangers in Medium-Depth Geothermal Heat Pump Systems

Deng

Wei

et al. 2020

Energies

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Deep borehole heat exchangers (DBHEs) extract heat from the medium-depth geothermal energy with the depth of 2-3 km and provide high-temperature heat source for the medium-depth geothermal heat pump systems (MD-GHPs). This paper focuses on the heat transfer performance of DBHEs, where field tests and simulation are conducted to analyze the heat transfer process and the influence factors. Results identify that the heat transfer performance is greatly influenced by geothermal properties of the ground, thermal properties and depth of DBHEs and operation parameters, which could be classified into external factors, internal factors and synergic adjustment. In addition, the long-term operation effects are analyzed with the simulation, results show that with inlet water temperature setting at 20 °C and flow rate setting at 6.0 kg/s, the average outlet water temperature only drops 0.99 °C and the average heat extraction drops 9.5% after 20-years operation. Therefore, it demonstrates that the medium-depth geothermal energy can serve as the hightemperature heat source for heat pump systems stably and reliably. The results from this study can be potentially used to guide the system design and optimization of DBHEs.

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Section: System Descriptionmentioning

confidence: 99%

Section: Analysis On the Influence Factors Of Heat Transfer Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Simulation Analysis on the Heat Performance of Deep Borehole Heat Exchangers in Medium-Depth Geothermal Heat Pump Systems

Deng

Wei

et al. 2020

Energies

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“…Market data shows that there is a sharp increase in the implementation and development of new heat pump technologies with higher coefficient of performances (COPs). At present, there is great interest in using heat pumps to save energy and using fuel and energy sources effectively …”

Section: Introductionmentioning

confidence: 99%

“…At present, there is great interest in using heat pumps to save energy and using fuel and energy sources effectively. [4][5][6] Currently, there are three main types of heat pumps namely water source heat pumps, ground source heat pumps and air source heat pumps. A ground watersource heat pump system with air pre-conditioning (GWHP-FAP) was proposed from the perspective of cascade utilization of low-level energy stored in the groundwater.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of defrosting and heating performance of a solar‐assisted heat pump integrated phase change energy storage

Chen

Zhang

et al. 2019

Int J Energy Res

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Summary This thesis investigates a novel solar‐assisted heat pump integrated phase change energy storage system. The defrosting performance of this system was studied experimentally and the results were compared with two traditionally used methods: reverse cycle defrosting (RCD) method and hot gas bypass defrosting (HGBD) method. The results show that the phase change energy storage system has superior performance compared with traditional defrosting methods. The indoor temperature drop recorded was relatively small and the defrosting time was 75% of the RCD system and 53% of HGBD system. The phase change energy storage system increased the condensation temperature which consequently increased the temperature difference of heat transfer resulting in higher conductivity in the defrosting progress. Compared with the method of RCD and the method of HGBD, the recovery time of the system was shortened by 90 and 160 seconds, respectively. The system works with low‐temperature heat source and circulating water, which considerably reduces energy consumption, thereby improving the performance of the defrosting system. A further experimental study was also conducted on the heating performance and the results also indicated that the value of COP can reach up to 3.6 in daytime, and the indoor temperature can be stably maintained above 18°C throughout the day. Novelty Statement A new defrosting method for energy storage defrosting is proposed, and the defrosting performance is compared with two common defrosting methods. In addition, the performances of the heating system over the day were experimentally investigated. The experimental results show the system meets the heating needs of the building. Finally, the influence of the outdoor temperature on the exergy efficiency of the system was discussed. It shows that this system can improve the operational stability, the system economy and energy saving.

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Development of distributed multiple‐source and multiple‐use heat pump system using renewable energy: Outline of test building and experimental evaluation of cooling and heating performance

Liu

Hino

Ooka

et al. 2020

Japan Architectural Review

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Field test on energy performance of medium-depth geothermal heat pump systems (MD-GHPs)

Cited by 80 publications

References 28 publications

Simulation Analysis on the Heat Performance of Deep Borehole Heat Exchangers in Medium-Depth Geothermal Heat Pump Systems

Simulation Analysis on the Heat Performance of Deep Borehole Heat Exchangers in Medium-Depth Geothermal Heat Pump Systems

Experimental analysis of defrosting and heating performance of a solar‐assisted heat pump integrated phase change energy storage

Development of distributed multiple‐source and multiple‐use heat pump system using renewable energy: Outline of test building and experimental evaluation of cooling and heating performance

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