지하수류가 밀폐형 천공 지중열교환기 성능에 미치는 영향(1)

한정상,한찬,윤운상,김영식,Hahn, Jeong Sang,Hahn, Chan,Yoon, Yun Sang,Kiem, Young Seek 한국지하수토양환경학회 2016 지하수토양환경 Vol.21 No.3

To analyze the influence of various groundwater flow rates (specific discharge) on BHE system with balanced and unbalanced energy loads under assuming same initial temperature (15℃) of ground and groundwater, numerical modeling using FEFLOW was used for this study. When groundwater flow is increased from 1 × 10⁻⁷ to 4 × 10⁻⁷m/s under balanced energy load, the performance of BHE system is improved about 26.7% in summer and 22.7% at winter time in a single BHE case as well as about 12.0~18.6% in summer and 7.6~8.7% in winter time depending on the number of boreholes in the grid, their array type, and bore hole separation in multiple BHE system case. In other words, the performance of BHE system is improved due to lower avT in summer and higher avT in winter time when groundwater flow becomes larger. On the contrary it is decreased owing to higher avT in summer and lower avT in winter time when the numbers of BHEs in an array are increased, Geothermal plume created at down-gradient area by groundwater flow is relatively small in balanced load condition while quite large in unbalanced load condition. Groundwater flow enhances in general the thermal efficiency by transferring heat away from the BHEs. Therefore it is highly required to obtain and to use adequate informations on hydrogeologic characterristics (K, S, hydraulic gradient, seasonal variation of groundwater temperature and water level) along with integrating groundwater flow and also hydrogeothermal properties (thermal conductivity, seasonal variation of ground temperatures etc.) of the relevant area for achieving the optimal design of BHE system.

강변여과수와 천부 지하수를 이용하는 지하수 열펌프시스템의 적정유량

한정상,한혁상,한찬,전재수,김형수,Hahn, Jeong-Sang,Han, Hyuk-Sang,Hahn, Chan,Jeon, Jae-Soo,Kim, Hyong-Soo 대한자원환경지질학회 2007 자원환경지질 Vol.40 No.6

지하수열펌프시스템(GWHP)은 지원열펌프시스템(GSHP)가운데 성능이 가장 우수하며 저온의 천부지하수열을 이용하는 시스템이다. GWHP시스템은 지중연결 열펌프시스템(GCHP)에 비해 최대 블록부하와 전 시스템 성능에 부합되는 지하수유량을 기준으로 하여 설계를 하며 최적 지하수유량은 해당지역의 지하수온도, 판형열교환기의 규격과 전체펌프와 배관류의 전 양정고에 따라 결정한다. 대체적으로 전형적인 빌딩루프순환수의 필요유량은 1RT당 $9.5{\sim}11.4lpm$ 정도인데 비해 GWHP시스템이 필요로 하는 최적 지하수유량은 이보다 꿜씬 적은 $3.8{\sim}9.5lpm$정도이다. The groundwater heat pump system(GWHP) is one of the most efficient ground source heat pump system(GSHP) which uses low grade and shallow geothermal energy for cooling and heating purpose. The GWHP system shall be designed properly based on peak block load performance and optimum pumping rate of groundwater comparable to ground coupled heat pump system(GCHP). The optimum pumping rate depends on groundwater temperature at a specific site, size of plate heat exchanger, and total head loss occurred by whole system comprising pumps and pipings. The required optimum flow rates of the system per RT are ranged from 3.8 to 9.8lpm being less than the typical building loop flow of 9.5 to 11.4lpm.

수주지열정(SCW)을 이용한 천부지열 냉난방시스템 설계지침

한정상,한혁상,한찬,김형수,전재수,Hahn, Jeong-Sang,Han, Hyuk-Sang,Hahn, Chan,Kim, Hyong-Soo,Jeon, Jae-Soo 대한자원환경지질학회 2006 자원환경지질 Vol.39 No.5

For the reasonable use of low grade-shallow geothermal energy by Standing Column Well(SCW) system, the basic requirements are depth-wise increase of earth temperature like $2^{\circ}C$ per every 100m depth, sufficient amount of groundwater production being about 10 to 30% of the design flow rate of GSHP with good water quality and moderate temperature, and non-collapsing of borehole wall during reinjection of circulating water into the SCW. A closed loop type-vertical ground heat exchanger(GHEX) with $100{\sim}150m$ deep can supply geothermal energy of 2 to 3 RT but a SCW with $400{\sim}500m$ deep can provide $30{\sim}40RT$ being equivalent to 10 to 15 numbers of GHEX as well requires smaller space. Being considered as an alternative of vertical GHEX, many numbers of SCW have been widely constructed in whole country without any account for site specific hydrogeologic and geothermal characteristics. When those are designed and constructed under the base of insufficient knowledges of hydrgeothermal properties of the relevant specific site as our current situations, a bad reputation will be created and it will hamper a rational utilization of geothermal energy using SCW in the near future. This paper is prepared for providing a guideline of SCW design comportable to our hydrogeothermal system. 내 수문지열계 가운데 수주지열정(SCW)시스템을 합리적으로 설치이용할 수 있는 조건들은 심도별 지온증가율이 명확하고($2^{\circ}C/100m$심도), 기존의 지하수 열펌프가 필요로 하는 순환수의 유량에 비해 최소 $10{\sim}30%$의 중온의 심부지하수가 산출될 수 있어야 하며, 순환수를 공내로 재주입시 공내붕괴가 일어나지 않는 견고한 암석들이 존재 하여야 한다. 수주지열정의 1개공당 굴착심도는 평균 $400{\sim}500m$이며, 이로 부터 개발가능한 지열에너지는 공당 약 $30{\sim}40RT$ 규모인데 비해 1개 수직지중열교환기가 공급가능한 지열에너지는 $2{\sim}3RT$ 정도이다. 즉 수주지열정 1개공은 $10{\sim}15$개의 수직지중열교환기 역할을 한다. 따라서 이 방식은 수직루프 설치장소의 공간 문제를 해소할 수 있는 유일한 대안으로 인식되어, 현재 전국 각지에서 많은 수의 SCW들이 무분별 하게 비과학적으로 설치되고 있다. 이와 같이 해당지역 수문지열계의 수리 지질학적인 특성과 열적인 특성을 명확히 파악하지 않은 상태에서 수주지열정을 설계 시공하는 경우에 나타날 문제점들은 추후 합리적인 천부지열 개발 이용에 지대한 장애요인이 될 것이다. 따라서 본고는 국내 수문지열계에 적합한 수주지열정을 설계 하는데 있어 필요한 일종의 지침서를 제시하기 위해 작성되었다.

제주도 지하수자원의 최적 개발가능량

한정상,한규상,김창길,김남종,한찬,Hahn, Jeong-Sang,Hahn, Kyu-Sang,Kim, Chang-Kil,Kim, Nam-Jong,Hahn, Chan 한국지하수토양환경학회 1994 지하수환경 Vol.1 No.1

제주도 지하수자원의 산출특성을 규명키 위하여 총 455개 기존관정의 자료를 전산처리하여 지역별 대수성 수리특성을 규명하였다. 제주도는 주로 현무암내에 협재된 화산쇄설층, crinker층과 현무암의 1 및 2차 유효공극이 주 대수대의 역할을 하며 이들은 기저, 준기저 및 상위대수층으로 구성되어 있다. 본도 대수층의 평균 투수량계수는 29,300 $m^2$/일이며 평 균 저유계수는 0.12로써 자유면 대수층을 이루고 있다. 종합적인 물수지 분석을 실시한 바 본도에 부존된 지하수 부존량은 약 440억 ㎥이고, 년평균 강수량은 33.9억 ㎥으로써 이 중 하천유출량은 6.38억㎥/년이며, 증발산량은 12.56억 ㎥/년(37%)이고 지하수함양량은 년평균 강수량의 44.1%에 해당하는 14.94억㎥이다. 본도에 부존된 지하수의 최적 개발가능량(sustainable yield) 을 각 지역별로 정량적으로 계산한 결과 그 양은 함양량의 41%에 해당하는 6.2억㎥/년(1,689,000 ㎥/일) 정도였으며 잔여 8.74억㎥/년(2,404,000㎥/일)은 해안이나 해저용천의 형태로 유출된다. 특히 최근에 실시한 심부 시추조사 자료에 의하면 EL-120$\pm$68m 부근에 저투수성 해성 퇴적층(일명 세화리층)이 분포되어 있는 것으로 판명되었으며 과거 서귀포층군으로 알려진 저투수성 퇴적층이 북서부와 서부 일원에서 EL-70m 부근에 널리 분포되어 있어 서귀포층군과 세화리층의 명확한 구분이 필요하다. 만일 이러한 저투수성 퇴적층이 제주도의 기저층을 이루는 경우 제주도 내에 부존된 지하수는 주로 준기저 지하수일 것이며 이는 제주도 지하수의 산출특성에 결정적인 영향을 미칠 것이다. The Hydrogeologic data of 455 water wells comprising geologic log and aquifer test were analyzed to determine hydrogeologic characteristics of the Cheju island. The groundwater. of the Cheju island is occurred in unconsolidated pyroclastic deposits and crinker interbedded in highly jointed basaltic and andesic rocks as high level, basal and parabasal types under unconfined condition. The average transmissivity and specific yield of the aquifer are at about 29,300㎡/day and 0.12 respectively, The total storage of groundwater is estimated about 44 billion cubic meters. Average annual precipitation is about 3,390 million ㎥ among which average recharge is estimated for 1,494 million ㎥ being equivalent 44.1% of total annual precipitation with 638 million ㎥ of runoff and 1,256 million ㎥ of evapotranspiration. Based on groundwater budget analysis, the sustainable yield is about 620 million ㎥(41% of annual recharge)and rest is discharging into the sea. The geologic logs of recently drilled thermal water wells indicate that very low-permeable marine sediments(Sehwa-ri formation) composed of loosely cemented sandy silt derived from mainly volcanic ashes at the 1st stage volcanic activity of the area is situated at the 120${\pm}$68m below sea level. Another low-permeable sedimentary rock called Seogipo-formation which is deemed younger than the former marine sediment is occured at the area covering north-west and western part of the Cheju island at the ${\pm}$70m below sea level. If these impermeable beds art distributed as a basal formation of fresh water zone of the Cheju island, the most of groundwater in the Cheju island will be para-basal type. These formations will be one of the most important hydrogeologic boundary and groundwater occurences in the area.

A Study on the Hydrogeologic Characteristics and Hydraulic Anisotropy of the Fractured Crystalline Rocks located in the Hilly Area

한정상(Jeong Sang Hahn),한규상(Kyusang Hahn) 대한지질학회 1992 지질학회지 Vol.28 No.1

미국 지하수자원의 최적관리기법과 보호전략에 관한 연구

한정상 ( Jeong Sang Hahn ) 대한지질공학회 1994 지질공학 Vol.4 No.1

Studies on Isotope Hydrology in South Korea

Jeong Sang Hahn(韓楨相),Jong Sung Ahn(安鍾成),Chang Kun Lee(李昌根) 대한지질학회 1984 지질학회지 Vol.20 No.1

Quantitative Hydrodispersion Study on Prediction of Groundwater Contamination, Ulsan Area, Korea

Jeong Sang Hahn(한정상),Ho Wan Chang(장호완),Kyu Sang Hahn(한규상),Kyung Seok Ko(고경석),Yong Dong Lee(이영동),Dae Ho Yoo(유대호) 대한지질학회 1991 지질학회지 Vol.27 No.1

현장 열응답시험과 현장 대수성시험결과를 동시 분석 가능한 통합전산 Program에 관한 연구

한정상(Jeong-Sang Hahn),한혁상(Hyuk-Sang Han),윤운상(Yun-Sang Yonn) 한국지열·수열에너지학회 2008 한국지열에너지학회논문집 Vol.4 No.1

Groundwater flow in confined aquifer and heat transport in underground geologic media are using same governing equation(line source) like well fuction. Therefore the conventional slope method using only later data obtained from in-situ thermal response test to determine the thermal conductivity of vertical geothermal heat exchanger(GHEX) is basically identical with one of Theis straight line method of aquifer test under artesian condition. In case that the pumping rate(Q, ㎥/d) and drawdown(s,m) which are used for input data of existing hydrogeologic computer programs for aquifer test are replaced and converted to supplying heat energy per unit length of bore hole(Q/L,w/m or Kcal/h.m) and temperatures (T,℃)measured at in and out-let of GHEX as in put data respectively, thermal conductivity around geothermal heat exchanger can be easily estimated without any special modification of the existing hydrogeologic computer program. Two numbers of time series temperature variation data obtained from in situ geothermal response test are analized using Theis methods(standard curve and straight line method) by using existing aquifer test program and conventional Slope method proposed by ASHRAE. The results show that thermal conductivity values estimated by two straight methods are identical and the difference of estimated values between standard curve methods and Slope method are also within acceptable ranges. In general,the thermal conductivity estimated from Theis straight line method gives more accurate value than the one of Slope method due to that Slope method uses only visual matching otherwise Theis method uses automatic curve matching estimation with reducing RSS.

Determination of Optimal Yield and Water Budget Analysis on Keumchon Well Field

한정상(Jeong Sang Hahn),한규상(Kyu Sang Hahn),이영동(Yong Dong Lee) 대한지질학회 1988 지질학회지 Vol.24 No.2