• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.2 no.2
• /
• pp.1-8
• /
• 2006

The objective of the present study is to investigate the load delivery characteristics of a hybrid-renewable energy system with geothermal and solar heat sources for hot water, heating and cooling of a residential house in Korea. The hybrid energy system consists of ground source heat pump of 2 RT for cooling with a 150 m vertical U-bend ground heat exchanger, solar collectors of 4.8 m2 and gas fired backup boiler. The averaged coefficient of performance of geothermal module during cooling and heating seasons are evaluated as about 4.5 and 3.8, respectively.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.6 no.1
• /
• pp.17-22
• /
• 2010

A sliding accident on the road have a high percentage by road freezing, especially, it is often appeared at bridges and tunnel of freezing areas. Thus, the stability of road operations is enhanced by preventing a partial freezing phenomenon. According to the geothermal snow melting system analysis, a pattern of thermal conductivity is found out about pavement materials of concrete and asphalt when it is buried. For the feasibility study on geothermal snow melting system, analysis of the ground melting point when operating system, life evaluation of pavements and safety evaluation of pipes are performed.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.7 no.2
• /
• pp.1-9
• /
• 2011

Geothermal heat pumps are known as the most efficient and environment-friendly heating and cooling system, and are also gaining acceptance in buildings. Building energy simulation program, EnergyPlus is used to calculate the energy consumption of residential buildings. This simulated energy consumption is essential for accurate economic analysis. Residential buildings with geothermal heat pumps have complex energy price structure. Electricity rates for residential buildings increase rapidly as the monthly use increases. This complex energy price structure makes the economic analysis complicated. The purpose of this study is to conduct economic comparison of residential geothermal heat pumps and provide a feasible approach in finding their economically feasible capacity.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.8 no.3
• /
• pp.1-11
• /
• 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.

• Economic and Environmental Geology
• /
• v.40 no.3 s.184
• /
• pp.307-318
• /
• 2007

The occurrence of geothermal water has high correlates highly with fossil geothermal system. A fuzzy logic based data integration is applied for geothermal potential mapping in the Southern Gyeongsang Basin which is distributed in the regional fossil geothermal system. Several data sets are related with the origin and distribution of fossil geothermal system, such as the geological map, the density of lineaments, the aerial survey map of magnetic intensity, the map of hydrothermal alteration, the distribution density of hydrothermal mines, which were collected as thematic maps for the integration. Fuzzy membership functions for all thematic maps were compared to the locations of the spa hot springs, which were used as ground-truth control points. After integrating all thematic maps, the results of gamma operator (${\gamma}=0.1$) was showed the highest success rate, and new geothermal potential zone is prospected in some area.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.688-692
• /
• 2005

Importance of substitute energy has been increasing due to environmental issues and lack of fossil fuels. In addition, heating cost that occupies from 30 to $40\%$ of the total production cost in Korean protected cultivation needs to be reduced for profitability and global competition. But, studying on substitute energy to solve these problems has not been activated for Korean protected cultivation. Therefore, this study was conducted to develop a geothermal heat pump system for cool ing and heat ing of greenhouses at a lower cost than conventional hot air heater and air conditioner. Fundamental test of heat transfer characteristics in soil was conducted by computer simulation and controlled tests for its verification. Based on the results of the theoretical and empirical investigations, an optimum heat pump system was developed and the performance was evaluated for practical use in a greenhouse at the Pusan Horticultural Experiment Station. The system was compared with a conventional hot air heating system through a cucumber growing test and economic feasibility analysis. Results of the application test of the geothermal heat pump showed that with an initial setting of $15^{\circ}C$ the inside temperature of the greenhouse could be maintained between 15 and $17^{\circ}C$. Results of the cucumber growing test showed that there were no significant differences in average height, leaf length, leaf width, number of nods, leaf area, dry weight and yield between the plots wi th the geothermal heat pump system and a conventional hot air heater. Economic feasibility analysis indicated that the variable cost of the hot air heater could be saved $81.2\%$ using the geothermal heat pump system. It was concluded that the geothermal heat pump system might be a pertinent heating and cooling system for greenhouses because of the low operating cost and the use of environment-friendly geothermal energy.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.13 no.1
• /
• pp.14-20
• /
• 2017

Groundwater heat pump (GWHP) system can achieve higher performance of the system by utilizing heat source of the annual constant groundwater temperature. The performance of GWHP system depends on the ground thermal environment such as groundwater temperature, groundwater flow rate and hydraulic conductivity. In this study, the geothermal environment was analyzed by using numerical simulation for develop the two-well geothermal system. As the result, this paper shows the change of the groundwater level and underground temperature around wells according to the conditions of flow rate and hydraulic conductivity.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.782-787
• /
• 2008

The Kalina cycle simulation study was carried out for a preliminary design of a geothermal power generation system. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The simulation results show that the power generation efficiency over 10% is expected when a heat source and sink inlet temperatures are $100^{\circ}C$ and $10^{\circ}C$ respectively.

• Journal of Korean Institute of Industrial Engineers
• /
• v.23 no.1
• /
• pp.115-127
• /
• 1997

A GDHS(Geothermal District Heating System) is a heating system supplying a group of districts with heat extracted from geothermal sources. The advantages of GDHS include saving fuel consumption as well as reducing air pollution. This paper presents a case study for the economic feasibility model and analysis of a GDHS with which central/individual heating systems are replaced. Configuring to a simplified GDHS which consisits of subsurface systems, surface systems, and transmission/distribution systems, we find out the properties of the system and the model parameters affecting the initial investment/operating costs in order to develop a classical economic feasibility model given geothermal temperature. Based on our model parameter space, we analyzed the geothermal development project of the Jejoo Island probabilistically given prior information such as the expected geothermal power, the demand size and the length of transmission/distribution pipes.

• The Journal of Engineering Geology
• /
• v.22 no.2
• /
• pp.233-241
• /
• 2012

The objectives of this study were to test geothermal conductivity (k), water velocity, water quantity, and pipe pressure from a ground heat exchanger in the field, and then to analyze these data in relation to the effectiveness and economical efficiency for application of geothermal energy. After installation of the apparatus required for field tests, geothermal conductivity values were obtained from three different cases (second, third, and fourth). The k values of the second case (506 m depth) and third case (151 m depth) are approximately 2.9 and 2.8, respectively. The k value of the fourth case (506 m depth, double pipe) is 2.5, which is similar to the second and third cases. This result indicates that hole depth is a critical factor for geothermal applications. Analysis of the field data (k, water velocity, water quantity, and pipe pressure) reveals that a single geothermal system at 506 m depth is more economically efficient than three geothermal systems at depths intervals of 151 m. Although it is more expensive to install a geothermal system at 506 m depth than at 151 m depth, test results showed that the geothermal system of the fourth case (506 m, double pipe) is more economically efficient than the system at 151 m depth. Considering the optional cost of maintenance, which is a non-operational expense, the geothermal system of the fourth case is economically efficient. Large cities and areas with high land prices should make greater use of geothermal energy.