지열 열펌프 시스템-SCW형 지중 열교환기 표준화에 대한 연구

김민준(Kim Min Jun),최충현(Choi Choong Hyun),전종욱(Jeon Jong UG) 표준인증안전학회 2013 표준인증안전학회지 Vol.3 No.1

This study is for development of the KS(Korea Standard) on the open loop GSHP, which uses the SCW(standing column well) as ground heat-exchanger. SCW ground heat-exchanger has higher heat-exchanging capacity than closed loop ground heat-exchanger because the SCW heat-exchanger can take ground heat source from ground water directly. The SCW ground heat-exchanger widely spread in various construction fields, due to the higher heat-exchanging rate. However almost all construction sites those use SCW ground heat-exchangers have installed by different design and installation procedure. Furthermore, engineers apply different measuring method for system performance according to the field specifications. This paper considered the standard of shape of SCW ground heat-exchanger, construction process, and measuring performance process for the GSHP system. The GSHP system’ reliability, which uses SCW ground heat-exchanger, can be guaranteed by using the recommended standard in this research.

Energy saving potentials from the application of heat pipes on geothermal heat pump system

Lim, Hyunjeong,Kim, Chanjoong,Cho, Yeonjoo,Kim, Minsung Elsevier 2017 Applied thermal engineering Vol.126 No.-

<P><B>Abstract</B></P> <P>A ground-loop heat exchanger is one of the key components to collect low grade ground heat for a ground source heat pump system. A typical ground source heat pump consists of a refrigerant loop operated by a compressor and a geothermal brine loop operated by a circulation pump. Although ground source heat pumps are known as one of the most efficient HVAC devices, their performance still need to be improved since the energy consumption by the peripherals like the circulation pump are considerable and estimated more than 10% of the total electricity input. In order to reduce the ground circulation energy, a variety of researches such as direct expansion geothermal heat pumps are studied, but no apparent performance improvement was found due to other negative effects like the increase of pressure drop in the ground loop. Geothermal heat pipe can be a good alternative to replace ground-loop heat exchanger for heating purpose. The energy saving potential using heat pipe as ground heat exchanger was investigated by comparing the energy consumption and COP of three types ground source heat pump. As a result, energy consumption for heating in Seoul by 10.3% than direct expansion ground source heat pump and 21.1% than secondary loop ground source heat pump. Therefore, ground source heat pump with geothermal heat pipe can be a suitable choice to save energy in a cold region.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The characteristics of vertical closed-loop ground source heat pumps were compared in a typical type, direct expansion type, and heat pipe type, respectively. </LI> <LI> The model to estimate ground temperature along the depth was improved reflecting the influence of local and seasonal climate. </LI> <LI> Annual performances of the three different types of ground source heat pumps were evaluated for Anchorage, Ottawa and Seoul. </LI> <LI> Circulation pumps for ground-loop heat exchanger are a main reason for poor performance at part-load operation. </LI> </UL> </P>

히트파이프 지중열교환기를 이용한 기후별 난방성능 해석

임현정(HyunJeong Lim),김찬중(Chan Joong Kim),오혜란(Hyeran Oh),김민성(Minsung Kim) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.11

A ground-loop heat exchanger is one of the key components to collect low grade ground heat for a ground source heat pump system. A typical ground source heat pump consists of a refrigerant loop operated by a compressor and a geothermal brine loop operated by a circulation pump. Although ground source heat pumps are known as one of the most efficient HVAC devices, their performance still need to be upgraded since the energy consumption by the peripherals like the circulation pump are considerable and estimated more than 10% of the total electricity input. In order to reduce the ground circulation energy, a variety of researches such as direct expansion geothermal heat pumps are studied, but no apparent performance improvement was found due to other negative effects like the increase of pressure drop in the ground loop. Geothermal heat pipe can be a good alternative to replace ground-loop heat exchanger for heating purpose. The energy saving potential using heat pipe as ground heat exchanger was investigated. In a cold region, ground source heat pump with geothermal heat pipe can be a great choice to save energy.

Numerical study on heat transfer characteristics in branch tube type ground heat exchanger

Choi, Hoon Ki,Yoo, Geun Jong,Pak, Jae Hun,Lee, Chang Hee Elsevier 2018 Renewable energy Vol.115 No.-

<P><B>Abstract</B></P> <P>A ground heat exchanger is an essential component of ground source heat pumps, which saves cooling and heating energy effectively. In this study, a branch tube type heat exchanger is suggested for a ground heat exchanger instead of commonly using the U-tube type for increasing heat transfer efficiency. The branch tube type heat exchanger has conjugate heat transfer including convective heat transfer between the walls of primary- and branch-tubes and internally circulating fluid, and conduction in the tube walls and grout. This conjugate heat transfer phenomenon is analyzed by steady 3-D numerical analysis using the finite volume method. In the analysis, temperature distribution, rate of heat transfer and pressure drop are compared for the branch tube type ground heat exchanger with 2, 4, 6, and 8 branch tubes together with a single U-tube type ground heat exchanger. Generally, the branch tube type shows better heat transfer performance compared to the U-tube type and the higher number of branch tubes give better heat transfer performance. Also, the branch tube type yields higher pressure drop than the U-tube type for the same mass flow rate of circulating fluid in the heat exchanger.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Branch tube type ground heat exchanger is proposed for enhanced heat transfer. </LI> <LI> Branch tube type ground heat exchanger has increased heat transfer area. </LI> <LI> The increased heat transfer rate is found in the out-flow region. </LI> <LI> Heat transfer rate is affected by number of branch tubes more than inlet velocity. </LI> </UL> </P>

건물의 침기율 모델링에 따른 지중 열교환기 용량 산정의 불확실성

백승효 한국건축친환경설비학회 2022 한국건축친환경설비학회 논문집 Vol.16 No.1

The length of ground heat exchangers is a key factor in the stable operation of ground-source heat pump systems. Different design variables or parameters such as the thermal properties of the ground and heat pump efficiency are considered in sizing ground heat exchangers. Among these, building heating and cooling loads are one of the most significant. However, a variety of uncertain parameters in the building simulation process makes it difficult to reliably estimate building heating and cooling loads. This study investigated the effects of uncertainty in estimating building heating and cooling loads on the sizing of ground heat exchangers, by considering the impact of changes in infiltration rate on these load and consequently on the size of the heat exchanger. EnergyPlus 9.4 was used to estimate the heating and cooling loads of a mid-rise residential building and GLHEpro 5.0 was used to determine the total length of ground heat exchangers. The results show that an increase in the infiltration rate caused an increase in peak building heating and cooling loads. Consequently, the required length of ground heat exchangers calculated by each zone and model differ. Additionally, sensitivity of the size of ground heat exchangers to changes in infiltration rate varied with different patterns of peak and yearly building loads. Therefore, sensitivity analysis of the major parameters used for estimating building heating and cooling loads is needed to ensure that the sizing of ground heat exchangers is robust.

지중 복원력을 고려한 지중 열교환기 등가 열해석 모델

백승효(Baek, Seung Hyo) 한국건축친환경설비학회 2020 건축환경설비 Vol.14 No.2

Ground temperature recovery has a considerable impact on the performance of ground heat exchangers and ground-coupled heat pump systems. Some studies have found that consideration of ground temperature recovery in the design of ground heat exchangers allows for a reduction in the size thereof. Based on this finding, this study first investigates whether previous design methods and thermal analysis models for ground heat exchangers are appropriate for the design considering ground temperature recovery. We find that assumptions regarding heat extraction made in previous design methods make it difficult to consider ground temperature recovery. Simplified thermal analysis models for ground heat exchangers are also required to support the design. For these purposes, this study proposes an equivalent thermal analysis model for ground heat exchangers. This model is validated against measurement data of a sand-box test, and validation results demonstrate good agreement. We expect that the proposed model contributes to proposing design methods considering ground temperature recovery.

하이브리드 지중열교환기 적용 지열 히트펌프 시스템의 난방 성능 분석

손병후(Byonghu Sohn) 한국지열·수열에너지학회 2020 한국지열에너지학회논문집 Vol.16 No.3

This paper presents the heating performance analysis results of a ground-source heat pump (GSHP) system using hybrid ground heat exchanger (HGHE). In this paper, the HGHE refers to the ground heat exchanger (GHE) using both a surface water heat exchanger (SWHE) and a vertical GHE. In order to evaluate the system performance, we installed monitoring sensors for measuring temperatures and power consumption, and then measured operation data with 4 different load burdened ratios of the HGHE. During the entire measurement period, the average heating capacity of the heat pump was 37.3 ㎾. In addition, the compressor of the heat pump consumed 9.4 ㎾ of power, while the circulating pump of the HGHE used 6.7 ㎾ of power. Therefore, the average heating coefficient of performance (COP) for the heat pump unit was 4.0, while the system including the circulating pump was 2.7. Finally, the parallel use of SWHE and VGHE was beneficial to the system performance; however, further researches are needed to optimize the design data for various load ratios of the HGHE.

건물일체형 지열히트펌프시스템의 난방 성능 분석

Jin Shangzhen,이진욱(Lee Jin-Uk),김태연(Kim Taeyeon),이승복(Leigh Seung-Bok) 한국태양에너지학회 2012 한국태양에너지학회 학술대회논문집 Vol.2012 No.3

Ground source heat pump is a central heating and cooling system that pumps heat to or from the ground. Building Integrated Geothermal system used in this experiment is one of the Ground Source Heat Pump Systems which utilize energy pile. The purpose of this study is to evaluate heating performance of the system. The building is a low-energy experiment apartment in Yonsei University Songdo Campus and the subject is one of the energy reduced houses in this apartment. In the experiment, indoor temperature, outdoor temperature and the inlet and outlet temperature of ground heat exchanger and subject model, were measured. Then the heat pump ' Coefficient of performance(COP) of the heat pump was calculated . As a result, the COP of heat pump is 4-5. Although the depth of the ground heat exchanger in this experment is shallower than usual heat exchanger, the result of heating performance of this system was good as well.

저심도 대구경 지중열교환기의 설치 및 성능 연구

유규상(Gyu Sang Yoo),박일문(Il Mun Park),신현준(Hyun-Joon Shin),민경천(Kyong Chon Min),최재호(Jae Ho Choi) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6

A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. We were carried out some tests to investigate the effects of some parameters such as borehole length and grouting materials of the Large borehole ground-loop heat exchanger. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. Ground effective thermal conductivity shows that cement grouting is 10% higher than soil grouting.

저심도 대구경 지중열교환기의 설치조건에 따른 성능 연구

유규상(Gyu Sang Yoo),박일문(Il Mun Park),최재호(Jae Ho Choi),신현준(Hyun-Joon Shin) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-

A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. Nowadays, precast concrete piles using steel reinforced precast concrete piles - energy piles - are used to reduce the installing cost of the ground-loop heat exchanger. We were carried out some tests to investigate the effects of some parameters such as borehole length, grouting materials and U-tube configuration of the energy piles. 4 concrete piles, each measuring 250㎜~400㎜ in diameter and approx. 10m in length, and rigged with single spiral and 3 U-tube loop of 16㎜ X 2.3㎜ PB piping. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. During the heating period, the energy piles absorb the heat of 0.89㎾ to 1.37㎾.