• Title/Summary/Keyword: geothermal study

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Analysis of HFC-245fa organic Rankine cycle for geothermal power generation (지열 발전을 위한 HFC-245fa 유기 랭킨 사이클의 성능해석)

  • Baik, Young-Jin;Kim, Min-Sung;Chang, Ki-Chang;Yoon, Hyung-Kee;Lee, Young-Soo;Ra, Ho-Sang
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.5 no.1
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    • pp.1-6
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    • 2009
  • In this study, an ORC (Organic Rankine Cycle) is investigated for a low-temperature geothermal power generation by a simulation method. A steady-state simulation model is developed to analyze cycle's performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump are modelled by an isentropic efficiency. Simulations were carried out for the given heat source and sink inlet temperatures, and given flow rate that is based on the typical power plant thermal-capacitance-rate ratio. HFC-245fa is considered as a working fluid of the cycle. Simulation results, at the given secondary working fluids conditions, show that even though the power can be presented by both the evaporating temperature and the turbine inlet superheat, it depends on the evaporating temperature primarily.

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A Performance Measurement and Evaluation of a 400RT Vertical type Geothermal System installed in a Complex Building Before Occupancy (복합용도 건물에 적용된 400RT급 수직형 지열시스템의 입주전 성능평가)

  • Hwang, Kwang-Il;Shin, Dong-Keol;Kim, Joong-Hun;Shin, Seung-Ho;Jung, Myoung-Kwan
    • Journal of the Korean Solar Energy Society
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    • v.28 no.3
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    • pp.7-14
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    • 2008
  • 400RT geothermal system which is the biggest capacity among on-operations at present in Korea is measured and evaluated on 23rd${\sim}$26th Jan. 2008 during those days building is not allowed owners and/or tenants to move in. The geothermal system is consist with vertical-typed 112 geothermal heat exchangers which are installed circle-like 1 row with 4m interval, and has 16 units of 25USRT geothermal-source heat pump(GSHP)s. And each 5 units of circulation pump are running for geothermal heat exchangers and hot water supplies. The followings are the results. The temperatures at G.L. -70m of 2 boreholes are varied quite similarly. The average temperature difference between inlet and outlet of geothermal pipes is $4.1^{\circ}C$, and that of hot water supply is $3.2^{\circ}C$, of Zone 3's each 4 GSHPs when being operated. Despite temperature fluctuations by heating loads, the average temperature difference between main pipes of inlet and outlet of geothermal heat exchangers is measured as $4.1^{\circ}C$. This study propose "Geothermal System COP" which includes not only consumed electric power by compressor but also circulation pumps and auxiliary utilities. By comparing the geothermal system COP with GSHP's performance specification, it is clear that the performances of GHSPs of this site are satisfied with the specification.

A Study on Deep Geothermal Energy and Potential of Geothermal Power Generation in Mongolia (몽골의 심부 지열에너지 자원과 지열발전에 관한 연구)

  • Hahn, Jeong-Sang;Yoon, Yun-Sang;Kiem, Young-Seek;Hahn, Chan;Park, Yu-Chul;Mok, Jong-Gu
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.8 no.3
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    • pp.1-11
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    • 2012
  • Mongolia has three(3) geothermal zones and eight(8) hydrogeothermal systems/regions that are, fold-fault platform/uplift zone, concave-largest subsidence zone, and mixed intermediate-transitional zone. Average temperature, heat flow, and geothermal gradient of hot springs in Arhangai located to fold-fault platform/uplift zone are $55.8^{\circ}C$, 60~110 mW/m2 and $35{\sim}50^{\circ}C/km$ respectively and those of Khentii situated in same zone are $80.5^{\circ}C$, 40~50 mW/m2, and $35{\sim}50^{\circ}C/km$ separately. Temperature of hydrothermal water at depth of 3,000 m is expected to be about $173{\sim}213^{\circ}C$ based on average geothermal gradient of $35{\sim}50^{\circ}C/km$. Among eight systems, Arhangai and Khentii located in A type hydrothermal system, Khovsgol in B type, Mongol Altai plateau in C type, and Over Arhangai in D type are the most feasible areas to develop geothermal power generation by Enhanced Geothermal System (EGS). Potential electric power generation by EGS is estimated about 2,760 kW at Tsenher, 1,752 kW at Tsagaan Sum, 2,928 kW at Khujir, 2,190 kW at Baga Shargaljuut, and 7,125 kW at Shargaljuut.

Performance Analysis for Open-loop Geothermal System with Spill-way technology by Real-scale Experiment (관정간 도수통로를 설치한 개방형 지열 시스템의 냉방성능 실험)

  • Kim, Hong kyo;Bae, Sangmu;Nam, Yujin;Jeoun, Oun;Oh, Jong Hyun;Lee, Byong Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.30 no.4
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    • pp.186-194
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    • 2018
  • A ground-source heat pump system (GSHP) is more energy efficient than other heat-source systems because it uses annual constant underground and water temperatures. Especially, two-well geothermal systems using groundwater as the heat source can achieve higher performance than closed-loop geothermal systems. However, performance of two-well geothermal systems is decreased by occurring overflow according to scale during long-term operations. Therefore, this study presents a two-well pairing geothermal system that controls the groundwater level of a diffusion well. In addition, a two-well pairing geothermal system and an SCW geothermal system were installed, and a comparative analysis of cooling performance depending on system operation under the same load conditions was conducted. The result was that the average heat pump coefficient of performance (COP) of the two-well pairing system was 6.5, and the entire system COP was 4.3.

A Study of the Influence of Groundwater Level on the System Performance of Open Loop Geothermal System (지하수 수위가 개방형 지열시스템 성능에 미치는 영향에 관한 연구)

  • Kim, Jinsang;Nam, Yujin
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.9 no.3
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    • pp.1-10
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    • 2013
  • Open loop geothermal heat pumps have great potential where the groundwater resources are sufficient. Performance of open loop geothermal heat pump systems is considered higher than that of ground source heat pumps. Head and power calculation of submersible pumps, heat pump units, and piping are numerically based on regression data. Results shows that the system performance drops as the water level drops, and the lowest flow rates generally achieve the highest system COPs. The highest achievable cooling system COPs become 6.34, 6.12, and 5.95 as the groundwater levels are 5m, 15m, and 25m. The highest heating system COPs also become 4.59, 4.37, and 4.20. Groundwater level and submersible pump selection greatly influence the system performance of open loop geothermal heat pumps. It needs to be analysed during the design process of open loop geothermal heat pump system, possibly with analysis tools that include wide range of pump product data.

Analysis on the Performance Evaluation Trends of Heat Pumps and the Test Standards of a Geothermal Heat Pump in Korea (히트펌프 성능 평가 동향과 국내 지열원 히트펌프 성능 평가 규격 및 제도 분석)

  • Kang, Shin-Hyung;Choi, Jong Min
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.13 no.4
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    • pp.31-38
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    • 2017
  • The heating and cooling air conditioning field has been increasing the problems of energy consumption and global warming in the world. A geothermal heat pump has been known as one of the highest efficient heating and cooling system. In this study, the analysis about the test standards of the geothermal heat pump of the Republic of Korea was executed. From the research, the following results were given. It is needed to address the domestic test standard for direct heat exchange geothermal heat pump. Water to air multi geothermal heat pump test standard was only developed in Korea. The test standard to calculate a seasonal energy efficiency ratio for cooling period and heat seasonal performance factor for heating period should be newly developed to estimate actual annual energy consumption and $CO_2$ emission.

Application and Revitalization Method of Domestic Geothermal Heat Pump System (국내의 지열에너지 열펌프 시스템 활용현황과 활성화 방안)

  • Park, Hye-Ri;Ko, Young-Ho;Kim, Min-Tae;Park, Jong-Li
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.922-927
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    • 2009
  • Due to the law of use of sustainable alternative energy recently legislated, many public institutions are ordered to use renewable energy. So it gets people's eyes on Geothermal energy system among other suggested renewable energy. Since there is hardly existence of a volcanic region, Geothermal heat pump system is generally used most in Korea. However, the important technology and materials are not localized and further, with only our technical skills it is arduous to popularize and develop Geothermal energy because of lack of revitalization related to the law and the regime for locally suitable Data-base. Moreover, an access of renewable energy is too much hard because of people's low interests about Geothermal energy. But fortunately, the well-studied about Geothermal heat system started to be adopted in many other provinces. Therefore, we study this with intend to popularize and develop Geothermal energy.

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A Feasibility Study on Geothermal Power Plant in Korea (한국형 지열발전 타당성 연구)

  • Lim, Hyo-Jae;Kwon, Jung-Tae;Kim, Geum-Soo;Chang, Ki-Chang
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.39-44
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    • 2009
  • Geothermal energy is the heat contained in the earth and its internal fluids. Geothermal energy is stored as sensible or latent heat. Supplied by both internal and external sources, it represents a vast supply which is only started to be tapped for generation of electric power. In general, this is natural dry or wet medium to high enthalpy steam at temperatures above $150^{\circ}C$. For some time, binary systems employing substances with a lower boiling point than water in a secondary circuit have been used to generate vapor for driving turbines at a lower temperature level. The utilization of binary plants and the possibility of production from enhanced geothermal systems can expand its availability on a worldwide basis. The geothermal electricity installed capacity is approaching the 10,000GW threshold. Geothermal energy is not present everywhere, but its baseload capability is a very important factor for its success.

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Development of Project Management System for Geothermal Well Construction (지열발전 시추공 구축 프로젝트관리시스템 개발)

  • Kim, Kwang-Yeom;Lee, Seung-Soo
    • New & Renewable Energy
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    • v.8 no.3
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    • pp.38-46
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    • 2012
  • Enhanced Geothermal System (EGS) among geothermal system types enables to produce sustainable energy even in non-volcanic region while conventional geothermal energy has been restricted to obtain only from hot and permeable formation such as in volcanic regions. Successful EGS project in terms of economy, however, can be expected only when the project is managed effectively considering most of influencing factors (e.g., tangible and intangible resources, cost, time, risks, etc.). In particular, well construction is of the utmost importance in geothermal project as it dominantly influences on time and cost in the whole project. Therefore, when it comes to viable geothermal project without abundant experience, managing drilling economically and efficiently is inevitable. In this study, a project management system for well construction in geothermal project based on project control system including work breakdown structure and cost account was developed to predict and assess the performance of drilling and to visualize the progress.

Cooling Performance of Geothermal Heat Pump using Alluvium Aquifer (충적대수층을 이용한 지열히트펌프시스템의 냉방성능)

  • Kang, Byung-Chan;Park, Jun-Un;Lee, Chol-Woo;Song, Yoon-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.561-566
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    • 2009
  • Alluvium is sedimentary stratum and composed of gravel, sand, silt, clay. Permeability of alluvium is the higher. If alluvium have lots of aquifer, will be of great use heat source and heat sink of heat pump. Alluvium aquifer contain the thermal energy of surrounding ground. Also geothermal heat pump using alluvium aquifer reduce expenses than general geothermal heat pump, because geothermal heat pump using alluvium aquifer make use of single well. In this study geothermal heat pump using alluvium aquifer was installed and tested for a building. The heat pump capacity is 30USRT. Temperature of ground water is in $12{\sim}17^{\circ}C$ annually and the quality of the water is as good as living water. The heat pump cooling COP is 4.4 ~ 4.7. The system cooling COP is 3.25 ~ 3.6. This performance is as good as BHE type ground source heat pump.

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