설계변수가 수직밀폐형 지중열교환기 설계길이에 미치는 영향

민경천(Kyong Chon Min),최재호(Jae Ho Choi) 한국지열·수열에너지학회 2011 한국지열에너지학회논문집 Vol.7 No.2

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 length and performance of the heat exchanger is dependent on the ground thermal conductivity, the operation hours, the ground loop diameter, the grout, the ground loop arrangement, the pipe placement and the design temperature. The result of this simulation shows that higher thermal conductivity of grouting materials leads to the decrease length of geothermal heat exchanger from 100.0 to 84.4%

지표수 열교환기의 용량과 적용 효과에 대한 설계 인자의 영향

손병후,민경천,Sohn, Byonghu,Min, Kyong-Chon 대한기계학회 2016 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.4 No.1

본 연구에서는 설계 인자가 지표수 열교환기 길이에 미치는 영향을 분석하였다. 또한 수직 밀폐형 지중열교환기와 지표수 열교환기를 같이 이용한다고 가정한 후, 지중 순환수의 온도 변화를 분석하였다. 지표수 열교환기 출구 온도와 연못 온도의 차이를 크게 하면, 열교환기 파이프 길이는 줄어들었다. 아울러 연못 온도가 높을수록 파이프 길이는 감소하지만, 파이프 바깥지름의 영향은 상대적으로 적었다. 또한 파이프 두께가 얇을수록 전도 열전달에서 열저항의 영향이 감소하기 때문에 파이프 길이는 감소하였다. 수직 밀폐형 시스템에 지표수 열교환기를 추가 적용하면, 지중열교환기 순환수 온도는 시간이 지날수록 감소하였다. Commercial buildings are generally cooling-dominated and therefore reject more heat to a vertical ground heat exchanger(GHE) than they extract over the annual cycle. Shallow ponds can provide a cost-effective means to balance the thermal loads to the ground and to reduce the length of GHE. The objective of this work has been to develop a design tool for surface water heat exchanger(SWHE) submerged in shallow pond. This paper presents the analysis results of the impact of design parameters on the length of SWHE and its application effect on geothermal heat pump(GHP) system using vertical GHE. In order to analysis, We applied ${\epsilon}-NTU$ method on designing the length of SWHE. Analysis results show that the required pipe length of SWHE was decreased with the increase of approach temperature difference and with the decrease of pipe wall thickness. In addition, when the SWHE was applied to the GHP system, the temperature of vertical GHE was more stable than that of standalone GHE system.

제어 방식에 따른 지열 히트펌프 시스템의 성능 시뮬레이션

이두영,최재호,민경천,손병후,Lee, Doo-Young,Choi, Jae-Ho,Min, Kyong-Chon,Sohn, Byonghu 대한기계학회 2016 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.4 No.1

지열 히트펌프 시스템에서 히트펌프 등 시스템 구성 요소의 에너지 소비량을 효율적으로 관리하면, 냉난방 성능을 더 높일 수 있다. 본 논문은 외기온도 제어 방식이 지열 시스템의 성능에 미치는 영향을 분석하였다. 또한 분석 결과를 현재 국내에서 주로 적용하는 제어 방식(Control-A)과 비교하였다. 이를 위해 상용 소프트웨어(TRNSYS 17)를 이용하여 가상 지열 시스템의 모델을 구축한 후, 시뮬레이션을 수행하였다. 외기 온도 제어 방식(Control-B)은 버퍼 탱크의 온도를 외기 온도에 따라 제어하기 때문에, 간절기 때 효과적이었다. 기존 제어 방식과 비교했을 때, 외기 온도 제어 방식은 히트펌프 전력 소비량을 7.7%(147 kWh 절감) 그리고 순환펌프 전력 소비량을 7.5%(28.1 kWh 절감) 줄일 수 있었다. Geothermal heat pump (GHP) systems have been proved to be one of the most efficient systems for heating and cooling in buildings. However, an optimal energy performance depends on a good control of the system components, including heat pumps and circulation pumps, which affect to the total energy consumption of system. This paper presents the simulation results of the heat pump performance for two different control schemes, i.e. constant setting temperature (Control-A) and variable setting temperatures (Control-B) in buffer tank. A dynamic simulation tool, TRNSYS 17, was used to model the entire system and to assess the performance of the system. Simulation results show that the Control-B, which controls the temperature in buffer tank with outdoor air temperature, is a effective way to reduce the energy consumptions in heat pump (7.7%) and circulation pump (7.5%).

지중열과 수열로 구성된 혼합열원 히트펌프 시스템의 난방성능분석

최홍식(Hong Sik Choi),민경천(Kyong Chon Min),손병후(Byonghu Sohn),임효재(Hyo Jae Lim) 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6

The purpose of this study is to examine the initial cost down effects of geothermal and hydrothermal mixed source heat pump. Generally, construction cost of ground heat exchanger is higher than that of hydrothermal, especially surface water heat exchanger. Thus the natural or artificial pond nearby can be used as good heat source and sink. The residence building was selected for experiment and systematical data acquisition was conducted for analysis. From three cases of test, geothermal, hydrothermal and mixed(geothermal+hydrothermal), we could get following results. Heat pump COP in heating is 3.3 for mixed case and 2.8 for ground only. Also, system COP in heating is 2.5 for mixed case and 2.9 for ground only. Because of the over estimated circulation pump, COP shows a little low. Thus additional study needs for cooling performance and for raising of COP.

냉각탑 병용 하이브리드 지열 히트펌프 시스템의 성능 분석

손병후,이두영,최재호,민경천,Sohn, Byonghu,Lee, Doo-Young,Choi, Jae-Ho,Min, Kyong-Chon 대한기계학회 2016 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.4 No.1

하이브리드 지열 히트펌프 시스템은 열원을 안정적으로 유지하기 위해 보조 히트싱크나 보조 열원을 활용한다. 본 연구에서는 병원 건물에 설치한 지열-냉각탑 하이브리드 시스템의 냉난방 성능을 분석하였다. 시스템에 각종 센서와 계측 장비를 설치하였으며, 2014년 2월부터 2015년 2월까지 측정한 데이터를 이용하여 성능을 분석하였다. 냉방 기간 중, 냉수 공급 온도는 평균 $11.7^{\circ}C$이었으며, 설계 온도인 $12^{\circ}C$를 넘지 않았다. 또한 난방 기간 중에는 일평균 $39^{\circ}C{\sim}40^{\circ}C$의 온수를 공급하였다. 지열 히트펌프만의 월 평균 성능지수는 3.8에서 8.4의 범위에서 변하였다. 반면 냉각탑을 포함한 하이브리드 지열시스템의 월 평균 성능지수는 2.6에서 6.6 사이에서 변하였다. This paper presents the measurement and analysis results for the performance of HGCHP system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from February 1, 2014 to February 28, 2015. Leaving load temperatures to building showed an average value of $11.7^{\circ}C$ for cooling and $39.5^{\circ}C$ for heating, respectively. From the analysis, the daily PF of hybrid GCHP system varied from 2.6 to 6.6 over the measurement period.

양방향 설정온도 제어에 따른 지중연계 히트펌프 시스템의 에너지 절감량 평가 연구

강은철(Eun-Chul Kang),이의준(Euy-Joon Lee),민경천(Kyong-Chon Min) 한국지열·수열에너지학회 2014 한국지열에너지학회논문집 Vol.10 No.2

Government has recently restricted heating and cooling set temperatures for the commercial and public buildings due to increasing national energy consumption. The goal of this paper is to visualize a future two way indoor set temperature control impact on building energy consumption by using TRNSYS simulation modeling. The building was modelled based on the twin test cell with the same dimension. Air source ground coupled heat pump performance data has been used for modeling by TRNSYS 17. Daejeon weather data has been used from Korea Solar Energy Society. The heating set temperature in the reference room is 24℃ as well as the target room set temperature are 23℃, 22℃ and 20℃. The cooling set temperature of the reference room is also 24℃ as well as the target room set temperature of 25℃, 26℃, 27℃ and 28℃. For the air source heat pump system, heating season energy consumption is 35.52 kWh/m²y in the reference room. But the heating energy consumption in the target room is reduced to 7.5% whenever the set temperature decreased every 1℃. The cooling energy consumption in the reference room is 4.57kWh/m²y. On the other hand, the energy consumption in the target room is reduced to 22% whenever the set temperature increased every 1℃ by two way controller. For the geothermal heat pump system, heating energy consumption in the reference room is reduced to 20.7%. The target room heating energy consu7mption is reduced to 32.6% when the set temperature is 22℃. The energy consumption in the target room is reduced to 59.5% when the set temperature is 26℃.

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.