• Title/Summary/Keyword: Air source heat pump(ASHP)

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A Study on Development of a Ground-Source Heat Pump System Utilizing Cast-in-place Concrete Pile Foundation of a Building (현장타설형 건물 기초를 이용한 지중열 공조시스템의 성능평가에 관한 연구)

  • Hwang, Suck-Ho;Nam, Yu-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.9
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    • pp.641-647
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    • 2010
  • Ground-source(Geothermal) heat pump(GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump(ASHP) systems. However, GSHP systems are not widespread because of their expensive installation costs. The authors have developed a GSHP system that employs the cast-in-place concrete pile foundations of a building as heat exchangers in order to reduce the initial cost. In this system, eight U-tubes are arranged around the surface of a cast-in-place concrete pile foundation. The heat exchange capability of this system, subterranean temperature changes and heat pump performance were investigated in a full-scale experiment. As a result, the average values for heat rejection were 186~201 W/m(per pile, 25 W/m per pair of tubes) while cooling. The average COP of this system was 4.6 while cooling; rendering this system more effective in energy saving terms than the typical ASHP systems.

A Study on Development of a Ground-Source Heat Pump System Utilizing Pile Foundation of a Building (건물 기초를 이용한 지중열 공조시스템의 개발에 관한 연구 (1))

  • Ryozo, Ooka;Nam, Yu-Jin;Kentaro, Sekine;Mutsumi, Yokoi;Yoshiro, Shiba;Hwang, Suck-Ho
    • Proceedings of the SAREK Conference
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    • 2005.11a
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    • pp.148-154
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    • 2005
  • Ground-source (Geothermal) heat pump (GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump (ASHP) systems. However, GSHP systems are not widespread in Japan because of their expensive boring costs. The authors have developed a GSHP system that employs the cast-in-place concrete pile foundations of a building as heat exchangers in order to reduce the initial boring cost. In this system, eight U-tubes are arranged around the surface of a cast-in-place concrete pile foundation. The heat exchange capability of this system, subterranean temperature changes and heat pump performance were investigated in a foil-scale experiment. As a result, the average values for heat rejection were 186${\sim}$201 W/m (for pile, 25 W/m per Pair of tubes) while cooling. The average COP of this system was 4.6 while cooling; rendering this system more effective in energy saving terms than the typical ASHP systems. The initial cost of construction per unit for heat extraction and rejection is ${\yen}$72/W for this system, whereas it is f300/W for existing standard borehole systems.

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Cooling Performance of a Ground Source Heat Pump System (지열히트펌프시스템의 냉방운전에 따른 성능연구)

  • Lee, Jae-Keun;Jeong, Young-Man;Koo, Kyoung-Min;Hwang, Yu-Jin;Jang, Se-Yong;Kim, In-Kyu;Jin, Sim-Won;Lee, Dong-Hyuk
    • Proceedings of the SAREK Conference
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    • 2007.11a
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    • pp.441-446
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    • 2007
  • This present study is to evaluate the cooling performance of a water-to-refrigerant ground source heat pump system(GSHP) under actually operating condition. 1 unit is selected among 10 units of the GSHP in the building to analyze the performance. The average cooling COP of the GSHP at the part load of 64% is 8.2, overall system COP is 6.19. In the GSHP system, the cooling temperature of the condenser is lower compared to the air source heat pump system. Conclusively, the cooling performance of the GSHP is higher than the air source heat pump system by 80%.

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Study on Optimization of Design and Operation for Groundwater Heat Pump System Considering Ground and Groundwater Condition (지반.지하수 조건을 고려한 최적의 지하수 이용 공조 시스템 선정에 관한 연구)

  • Nam, Yu-Jin;Ryozo, Ooka;Hwang, Suck-Ho
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.731-736
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    • 2006
  • Groundwater heat pump (GWHP) system has been expected to achieve the higher coefficient of performance (COP) and more energy-saving than the conventional air-source heat pump (ASHP) system. Its performance significantly depends on the characteristics of groundwater and the underground thermal properties. Furthermore, there is a large difference of COP in utilizing groundwater between as a heat resource and as a thermal storage medium. For properties of groundwater there is suitable utilizing system. However, many of GWHP systems have not been considered sufficiently such properties. This research describes optimization of GWHP system according to the properties of groundwater based on 3D numerical heat and water transport simulation.

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Toward residential building energy conservation through the Trombe wall and ammonia ground source heat pump retrofit options, applying eQuest model

  • Ataei, Abtin;Dehghani, Mohammad Javad
    • Advances in Energy Research
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    • v.4 no.2
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    • pp.107-120
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    • 2016
  • The aim of this research is to apply the eQuest model to investigate the energy conservation in a multifamily building located in Dayton, Ohio by using a Trombe wall and an ammonia ground source heat pump (R-717 GSHP). Integration of the Trombe wall into the building is the first retrofitting measure in this study. Trombe wall as a passive solar system, has a simple structure which may reduce the heating demand of buildings significantly. Utilization of ground source heat pump is an effective approach where conventional air source heat pump doesn't have an efficient performance, especially in cold climates. Furthermore, the type of refrigerant in the heat pumps has a substantial effect on energy efficiency. Natural refrigerant, ammonia (R-717), which has a high performance and no negative impacts on the environment, could be the best choice for using in heat pumps. After implementing the eQUEST model in the said multifamily building, the total annual energy consumption with a conventional R-717 air-source-heat-pump (ASHP) system was estimated as the baseline model. The baseline model results were compared to those of the following scenarios: using R-717 GSHP, R410a GSHP and integration of the Trombe wall into the building. The Results specified that, compared to the baseline model, applying the R-717 GSHP and Trombe wall, led to 20% and 9% of energy conservation in the building, respectively. In addition, it was noticed that by using R-410a instead of R-717 in the GSHP, the energy demand increased by 14%.

Heating Performance of a Ground Source Heat Pump System through Actual Operation (지열원 히트펌프시스템의 실사용을 통한 난방성능연구)

  • Koo, Kyoung-Min;Jeong, Young-Man;Hwang, Yu-Jin;Lee, Jae-Keun;Jang, Se-Yong;Kim, In-Kyu;Jin, Sim-Won;Lee, Dong-Hyuk
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.1341-1346
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    • 2008
  • This paper presents the heating performance of a water-to-refrigerant type ground source heat pump system (GSHP) installed in a school building. The evaluation of the heating performance has been conducted under the actual operating conditions of GSHP system in the winter. Ten units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. For analyzing the heating performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the heating capacity and the input power were evaluated for determining the heating performance of the GSHP system. The average heating coefficient of performance (COP) of the heat pump was found to be 5.1 at partial load of 46.9%, while the overall system COP was found to be 4.2.

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Heating Performance of a Ground Source Heat Pump System through Actual Operation (지열원 히트펌프시스템의 실사용을 통한 난방성능연구)

  • Koo, Kyoung-Min;Jeong, Young-Man;Hwang, Yu-Jin;Lee, Jae-Keun;Jang, Se-Yong;Kim, In-Kyu;Jin, Sim-Won;Lee, Dong-Hyuk
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.788-793
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    • 2008
  • This paper presents the heating performance of a water-to-refrigerant type ground source heat pump system (GSHP) installed in a school building. The evaluation of the heating performance has been conducted under the actual operating conditions of GSHP system in the winter. Ten units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. For analyzing the heating performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the heating capacity and the input power were evaluated for determining the heating performance of the GSHP system. The average heating coefficient of performance (COP) of the heat pump was found to be 5.1 at partial load of 46.9%, while the overall system COP was found to be 4.2.

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