• Journal of Environmental Science International
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• v.12 no.6
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• pp.583-591
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• 2003

The research on potential energy was conducted to conserve the high-exergy energy like primary energy and utilize waste heat from sewage. From the Point of view in using the waste heat, the energy Potential of waste water from the model house was simulated. From the results, when the heated water was supplied to the model house side in order to put unused energy to Practice use, heated water had higher energy Potential than unheated water, which was due to the discharge of most of unused energy. The possessing heat capacity of sewage from heated water was increased to 40-70 percents in comparison with that from the unheated water. Therefore, it can be used as energy source for improving coefficient of performance of heat pumps. By adopting the multiple heat pump into a model house, It showed that the possessing heat capacity of sewage was reduced. It was also found that the heat was recovered as energy source fur multiple heat pump in a model house.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.215-220
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• 2006

Along with socioeconomic development and improving standard of living, the heat demand for heating and cooling in residential and commercial sectors is expected to expand rapidly, reaching over 43 million TOE by 2010 in Korea(about 80% increase compared with that in 1995). Since most of this heat demand is loop temperature below $60^{\circ}C$, the utilization of 'unused energy' is surely one of very effective measures to both environmental preservation and energy conservation. 'Unused energy' in this paper is implicated as 'temperature differential energy' available from treated sewage water, useful and abundant heat source for heat pump(cooler in summer and warmer in winter than outside air). An analysis was carried out to estimate the energy potential of treated sewage water for heat pump heat source. Some analysis were taken to study the characteristics of a heat pump system using the treated sewage water as heat source.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.171-178
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• 2006

In advanced countries, state-of-the-art temperature monitoring technique is widely used for effective use of geothermal resources. But these kind of modern tools such as Thermal Line Sensor has not been applied to find geothermal characteristics of alluvium and riverbed in domestic area. In this research, state-of-the-art thermal line temperature sensor monitoring was introduced. And long term field test using this type of sensor was performed to find geothermal characteristics of alluvium and riverbed and evaluate the availability for heat energy source. As a result, temperature monitoring technique through thermal line sensor was very effective to obtain basic geothermal information of alluvium deposit and riverbed. Also, it was found that the groundwater temperature phase showed its potential of utilization as a energy source of heat pump. It is estimated that further study shows a specific corelation between temperature monitoring data and its availability as a energy source.

• Journal of Hydrogen and New Energy
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• v.24 no.6
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• pp.510-517
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• 2013

The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.56-61
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• 2009

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.1
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• pp.23-31
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• 2011

The objectives of this study are to analyze the performance of a heat pump system with the various heat source and to carry out economic assessment for the heat pump system. The COP of the river water and ground source heat pump system was 20% higher than that of the air source heat pump system because river water and geothermal provide stable operating temperature compared with air temperature throughout the year. In addition, the economic assessment of a heat pump system using air, river water, and geothermal as a heat source was carried out. The ratio of the life cycle operating cost to the life cycle cost increased with the increase of building capacity. The payback period was found to be less than 3.3 and 4.5 years, respectively when the capacity of the river water and ground source heat pump was larger than 10 RT.

• Journal of the Korean Solar Energy Society
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• v.34 no.2
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• pp.53-59
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• 2014

Ice Rink is energy intensive building type. Concern of energy saving from buildings is one of very important issues nowadays. New and renewable energy sources for buildings are especially important when we concern about energy supply for buildings. Among new and renewable energy sources, use of seawater for heating and cooling is an emerging issue for energy conscious building design. The options of energy use from sea water heat sources are using deep sea water for direct cooling with heat exchange facilities, and using surface layer water with heat pump systems. In this study, energy consumptions for an Ice Rink building are analyzed according to the heat sources of air-conditioning systems; existing system and sea water heat source system, in a coastal city, Kangnung. The location of the city Kangnung is good for using both deep sea water which is constant temperature throughout the year less than $2^{\circ}C$, and surface layer water which should be accompanied with heat pump systems. The result shows that using sea water from 200m and 30m under sea lever can save annual energy consumption about 33% of original system and about 10% of that using seawater from 0m depth. Annual energy consumption is similar between the systems with seawater from 200m and 30m. Although the amount of energy saving in summer of the system with 200m depth is higher than that with 30m depth, the requirement of energy in winter of the system with 200m depth is bigger than that with 30m depth.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.434-440
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• 2007

The Effluent ground water overflows in deep and broad ground space building. Temperature of effluent ground water is in 12$\sim$18$^{\circ}C$ annually and the quality of that water is as good as living water. Therefore if the flow rate of effluent ground water is sufficient as source of heat pump, that is good heat source and heat sink of heat pump. Effuent ground water contain the thermal energy of surrounding ground. So this is a new application of ground source heat pump. In this study open type and close type heat pump system using effluent ground water was installed and tested for a church building with large and deep ground space. The effluent flow rate of this building is 800$\sim$1000 ton/day. The heat pump capacity is 5RT each. The heat pump system heating COP was 3.0$\sim$3.3 for the open type and 3.3$\sim$3.8 for the close type system. The heat pump system cooling COP is 3.2$\sim$4.5 for the open type and 3.8$\sim$4.2 for close type system. This performance is up to that of BHE type ground source heat pump.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.8
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• pp.605-611
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• 2012

The objective of this study is to investigate the influence of the cooling performance for a water-to-water 10 RT ground source heat pump by using the water switching and refrigerant switching method. The test of water-to-water ground source heat pump was measured by varying the compressor speed, load side inlet temperature, and ground heat source side temperature. The cooling capacity and refrigerant mass flow rate of the heat pump increased with increasing ground heat source temperature. But COP of the heat pump decreased with increasing ground heat source temperature. As a result, the water switching method with counter flow, compared to a refrigerant switching method, improves the cooling capacity and COP by approximately 6~9% in average, respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.35-40
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• 2006

Heat-pump system has a special feature that provides heating operation in winter season and cooling operation in summer season with a single system. It also has a merit that absorbs and makes use of wastewater heat, terrestrial heat, and heat energy from the air. Because heat-pump system uses midnight electric power, it decreases power peak load and is very economical as a result. By using the property that energy source is converted to low temperature when losing the heat, high temperature energy source is used to provide heating water and low temperature energy source is used to provide cooling water simultaneously in summer season. This study made up a heat-pump system with 4 air heat sources and a water heat source and implemented the optimal operation algorithm that works with numbers of heat pumps to operate them efficiently. With the heat-pump system, we applied it to cooling and heating operation in summer season operation mode in a real building.