• 한국지열·수열에너지학회논문집
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• 제8권3호
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• pp.29-35
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• 2012

Geothermal heat pump system has been spotlighted as an efficient building energy system, because it has great potentials for reducing energy in building air conditioning and reducing $CO_2$ emissions. However, higher initial cost is a barrier to the promotion of its use. Energy-pile and energy-slab are known as low cost ground heat exchangers comparing with conventional ground heat exchangers, because they utilize building structures as ground heat exchangers. This paper presents the daily cooling performance of a geothermal heat pump system with energy-pile and energy-slab. The energy-piles and the energy-slabs are connected to heat pump units in parallel. The cooling capacity of the system was nearly constant due to the stability of the ground heat exchangers. The stability of the energy-pile was a little higher than that of the energy-stab as a heat sink.

• 한국지열·수열에너지학회논문집
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• 제11권3호
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• pp.7-12
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• 2015

Currently water supply system with water storage is generally applied except for small building such as single-family houses, and water supply system on replacing water storage installed system by direct connecting system has been increasing because of sanitary and energy-saving aspects. The purpose of this study is to evaluate energy-saving and environmental efficiency of direct connecting booster pump system in comparison with the water storage installed system. The architectural condition of the evaluation subject is ten-story apartment house in which sixty households live. To calculate the power consumption of the pump, the volume of water supply was determined from existing data and other data, such as head, efficiency of the pump, was the value used for general application in design office. The power consumption of the water supply pump for one day was 8.5 kWh for direct connecting booster pump system, and 22.5 kWh for water storage installed system, and the former system showed energy savings of 62% compared to the latter system. Reduced power consumption also leads to reduction of $CO_2$ emission. According to the criteria presented in the Korea Energy Management Corporation, reducing the 2,410 kg $CO_2$ emission is possible per year.

• 한국태양에너지학회 논문집
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• 제32권5호
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• pp.59-67
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• 2012

In this study,the compact type solar thermal and ground coupled heat pump hybrid system for space heating/cooling and hot water supply has been developed. This hybrid system was installed in Zero Energy Solar House(ZeSH) in KIER for the demonstration. The thermal performance and operational characteristics of this hybrid system were analysed especially. The results are as follows. (1) This hybrid system was designed in order to address the existing disadvantages of solar thermal/ground coupled heat pump system. For this design, all parts except solar collector and ground coupled heat pump were integrated into a single product in a factory. The compact type unit includes two buffer tanks, an expansion tank, pumps, valves, a controller, etc. This system has an advantage of easy installation with simple plumbing work even in narrow space. (2) The thermal charging and discharging time of the buffer tanks and its characteristics by ground coupled heat pump, and heat pump COP according to geo-source temperature and buffer storage temperature have been studied. This system was found to meet well to the heat load without any other auxiliary heating equipment. (3) The operating hours of the ground coupled heat pump as a backup device of solar thermal can be reduced significantly by using solar heat. It was also found that the minimum heating water supply setting temperature and maximum cooling water supply setting temperature make an influence on the heat pump COP. The lower heating water and the higher cooling water temperature, the higher COP. In this respect, the hybrid system's performance can be improved in ZeSH than conventional house.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.299-303
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• 2008

The treated sewage temperature is about $5^{\circ}C$ lower in summer and $5{\sim}10^{\circ}C$ higher in winter than ambient air. It can be used heat pump heat source and is good heat source on high performance of heat pump. In this study, to develop 100RT 2-stage compression heat pump use treated sewage water heat source and system applies to sewage disposal plant. Although heat pump is better performance, the large temperature difference between load and source makes the performance degradation of a heat pump. To solve this problem screw 2-stage compression is considered. The experiment was focused on the system operating performance variations over supply water and treated sewage water a temperature in the field. The results show that system of heating performance is higher then general heat pump and is enough to supply a hot water of $70^{\circ}C$.

• 한국유체기계학회 논문집
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• 제18권2호
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• pp.67-72
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• 2015

The purpose of this study is to achieve energy saving effect of inverter driving multistage centrifugal pump. For determining the operation points in the pump system, the system curves should be obtained experimentally. To get the system curves, three pumps combined in parallel and one pump operated with different rotational speeds. But for variable speed pump system, energy saving rates can not be evaluated from operation efficiencies. That is why operation efficiencies, system curves, duty cycles, and input powers of the pump system were measured by the constructed experimental apparatus. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated with two different periods. The mean duty cycles were collected from apartment and found that the system operated at 40% and at 50% or below capacity. Measured energy saving rate was 58.16%. Estimating method of energy saving rate could be more effective operation index than that of operation efficiency.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.7-12
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• 2018

Energy performance of electric heater and geothermal source heat pump type hot air dryers are compared in this study. For set temperatures of $30^{\circ}C$, $35^{\circ}C$ and $40^{\circ}C$, radish is dried from initial mass 60 kg until it gets 5 kg, where the difference equals the amount of water removed. As set temperature is increased, drying time is shortened for both electric heater and heat pump types, however energy efficiency is decreased due to increasing electricity consumption. Moisture extraction rate(MER) of electric heater is 2.58~2.84 kg/h, and for heat pump type 2.56~2.71 kg/h, showing little difference between the two types. Specific moisture extraction rate (SMER) of electric heater is 0.94~0.96 kg/kWh, and for heat pump type 1.72~2.21 kg/kWh. SMER of heat pump type is greater by 0.78~1.25 kg/kWh than the electric heater hot air dryer, which is 1.8~2.3 times better in terms of energy efficiency.

• 한국태양에너지학회 논문집
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• 제35권1호
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• pp.45-52
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• 2015

The government is fostering a renewable energy industry as an alternative to handle the energy crisis. Among the renewable energy systems available, geothermal energy is being highlighted as being highly efficient and safely operable without the effect of outdoor air. Accordingly, a study on the geothermal heat pump is in progress in various worldwide perspective. However, Geothermal energy is only in charge of part load of the building due to the high initial installation cost in korea. Moreover, its efficiency is reduced due to the use of independent existing heat sources. In this study, after selecting the building containing the actual installed geothermal heat pump, the use of excellent geothermal heat pump systems was maximized in terms of the energy efficiency. The objective of this study is to show the operation method of geothermal heat pump system to improve energy efficiency through the TRNSYS simulation. This paper proposed operation methods of geothermal heat pump control according to outdoor air temperature. The result of this study is that existing operation method had some problems and if offered improvement is applied to real condition, energy consumption would be decreased.

• KIEAE Journal
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• 제15권3호
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• pp.57-63
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• 2015

Purpose: Ground source heat pump system has been attracted in the horticulture industry for the reduction of energy costs and the increasing of farm income. Even though it has higher initial costs, if it uses in combination with heat storage, it is able to reduce the initial costs and operate efficiently. In order to have significant effect of heat storage type ground source heat pump system, it is required to design the capacity considering various conditions such as energy load pattern and operating schedule. Method: In this study, we have designed heat storage type ground source heat pump system in 5 cases by the operating schedule, and examined the system to find the most economic and having superb performance regarding the system COP(Coefficient of Performance) and energy consumption, using dynamic energy simulation, TRNSYS 17. Result: Conventional ground source heat pump system has lower energy consumption than heat storage type, but following the result of LCC(Life Cycle Cost) analysis, the heat storage type was more economic due to the initial costs. In addition, it has the most efficient performance and energy costs in the case of the smallest heat storage time.

• 설비공학논문집
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• 제30권4호
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• pp.167-174
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• 2018

The geothermal heat pump systems were installed for heating and cooling of public buildings in Jincheon Eco-friendly Energy town. The heat pump system was operated at night to save on operational costs, and the cold heat was stored in thermal energy storage (TES). In this study, the performance of geothermal heat pump systems with the TES during the summer season was analyzed, and the operational costs with and without the TES were compared. The electric chiller model was used to simulate a heat pump applied without the TES system. Electric rates of each system were measured to calculate operational costs. When the TES is used in the air conditioning system, the electric load (30.4 MWh) calculated in the daytime can move to off-peak load time, and the operational cost is reduced by 36~54%.

• 대한건축학회논문집:구조계
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• 제34권11호
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• pp.81-87
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• 2018

Among various types of geothermal heat pump systems, Vertical Closed-Loop Geothermal Heat Pump (VGSHP) has received increasing attention due to a variety of advantages such as the potential to be installed in a relatively small space and improved energy efficiency. In this research, the performance of VGSHP system coupled with heat storage tank was evaluated, by analyzing operational behavior of heat storage tank, the variations of heat pump energy performance due to the connection with heat storage tank, part load ratios characteristics of heat pump and the corresponding energy cost, compared to chiller and boiler based conventional system. The results of this study showed that the VGSHP system coupled with heat storage tank showed an energy saving effect of about 18% for cooling and about 73% for heating, and annual heating/cooling energy cost reduction of 43,000,000 KRW ($ 39,000), compared to the conventional air conditioning system. In addition, after considering both energy cost and initial investment cost including equipment, installation and auxiliary device expenses, payback period of approximately 11.8 years was required.