• 신재생에너지
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• 제3권4호
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• pp.22-30
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• 2007

An expansion device plays an important role in optimizing the heat pumps by controlling refrigerant flow and balancing the system pressures. Conventional expansion devices are being gradually replaced with electronic expansion valves due to increasing focus on comfort, energy conservation, and application of a variable speed compressor. In addition, the amount of refrigerant charge in a heat pump is another primary parameter influencing system performance. In this study, the flow characteristics of the expansion devices are analyzed, and the effects of refrigerant charge amount on the performance of the heat pump and the variation of compressor speed are investigated at various operating conditions. Mass flow rate through capillary tube, short tube orifice, and EEV was strongly dependent on the upstream pressure and subcooling. The heat pump system is very sensitive with a variation of refrigerant charge amount. The performance of it can be optimized by adjusting the flow rate through expansion device to maintain a constant superheat at all test conditions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.592-595
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• 2009

In recent years, geothermal heat pump (GHP) systems have become increasingly popular for heating and cooling in buildings. The Standing Column Well (SCW) method is one of the most efficient GHP system. Because it use groundwater for heat transfer material. In SCW systems, water is re-circulated between the well and the building (heat pump). It is only a short time since this method has been applied in domestic. So we have to refer to the developed countries' guides and manuals of SCW. In this paper, several design and construction points of SCW method are filed. We used real operation data of SCW system at Chong-Ju Univ. site for economical efficiency analysis. As a result, the payback period of Chong-Ju Univ. site is calculated at 7.23 years.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.470-473
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• 2007

Geothermal heat exchanger(GHEX) is a major component of Geothermal heat pump system(GSHPs). In Common, We use the vertical type GHEX in Korea. But vertical type GHEX needs a high cost for installation, because of drilling the hole which has 200m depth at max. So, We suggest the use of horizontal type GHEX. When we construct buildins, We excavate the ground and we can install the horizontal type GHEX at the excavated underground. It's very cheap and convenient method compare to vertical type GHEX installation. This study is peformed to estimate the peformance of horizontal type GHEX and to analyze effects of heat exchanger types and undergroundwater. As the result, slinky type GHEX has a 66% efficiency compare to vertical type GHEX and mat type has a 201% efficiency at the undergroundwater zone.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.36-39
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• 2006

To evaluate the effect of groundwater flow on the outlet temperature of a geothermal heat pump, 3 dimensional numerical simulations are performed considering both groundwater flow and pipe flow in the U-tube using TOUGHS, The present study involved the following 4 simulation cases (1) no groundwater flow, (2) slow groundwater flow (hydraulic conductivity: $1.0{\times}10^{-9}m/s)$, (3) fast groundwater flow (hydraulic conductivity, $1.0{\times}10^{-7}m/s$), and (4) groundwater flow varying with the depth (hydraulic conductivity: $1.0{\times}10^{-7}-1.0{\times}10^{-10}m/s$). The effect of groundwater flow on the outlet temperature is significant where hydraulic conductivity of aquifer is $1.0{\times}10^{-7}m/s$. Where hydraulic conductivity of aquifer is $1.0{\times}10^{-10}m/s$, however, that effect is negligible.

• 한국유체기계학회 논문집
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• 제6권2호
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• pp.29-33
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• 2003

The periphery pump (or regenerative pump) has been generally applied in the automotive fuel pump due to their low specific speed (high heads and small flow rate) with stable performance curves. In this study, the performance prediction of side channel type periphery pumps has been developed. The prediction of the circulatory flow rate is based on the consideration of the centrifugal force field in the side-channel and in the impeller vane grooves. For the determination of performance curve (head-flow rate), momentum exchange theory is used. The effects of various geometric parameters and loss coefficients used in the performance prediction method on the head and efficiency are discussed, and the results were compared with experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.581-584
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• 2002

The periphery pump(or regenerative pump) has been generally applied in the automotive fuel pump due to their low specific speed(high heads and small flow rate) with stable performance curves. In this study, the performance prediction of side channel type periphery pumps has been developed. The prediction of the circulatory flow rate is based on the consideration of the centrifugal force field in the side-channel and in the impeller vane grooves. For the determination of performance curve(head-flow rate), momentum exchange theory is used. The effects of various geometric parameters and loss coefficients used in the performance prediction method on the head and efficiency are discussed and the results were compared with experimental data.

• 대한기계학회논문집B
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• 제30권1호
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• pp.16-23
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• 2006

The present study aims at establishing the design procedure of regenerative pumps. It is based on the new momentum exchange theory proposed in Yoo, Park and Chung. Salient feature of the present design procedure is that it does not require input of any kinds of empirical design data. Using the design procedure, a prototype regenerative pump has been designed and manufactured to confirm its validity. Comparison between the predicted performance and the experimental measurement reveals that the prototype pump has its maximum efficiency at the design flow rate and that the proposed performance analysis method satisfactorily predicts the machine performance.

• 설비공학논문집
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• 제9권3호
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• pp.333-342
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• 1997

An experimental study has been carried out to investigate the effects of the combination of the different wire mesh number in a regenerator and the tube number in a cooler on the cooling performance of a Vuilleumier cycle heat pump. Effects of operating conditions, such as charging pressure, operating speed, and heat input, on the cooling performance are also studied. The experimental results obtained indicate that the cooling performance could be improved with the proper combination of different wire meshes in a regenerator. More tubes in a cooler are desirable for better cooling performance. It is also found that the cooling capacity is enhanced, whereas COP is reduced with an increase in the heater tube temperature and the revolution speed. Both the cooling capacity and COP are incereased with a higher charging pressure.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.217-220
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• 2007

The purpose of study is a development of the high reliance electric driven water-pump that fuction is forcing the movement of water using basic design, proto sample and test at the cooling system. It was important to supply a coolant quickly and accurately for the requirement of flow rate at the system when we carried out the designs for BLDC Motor, Controller and water pump(Impeller, Volute Casing, Sealing Device) First, we attained ours purpose that the target efficiency for water pump was over 40% and then we are doing the optimum design for Brushless Motor and Controller that its target is over 55% of efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.519-524
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• 2007

In this study, NR GT 101 (water-to-water Ground source heat pump unit) and NR GT 102 (water-to-air Ground source heat pump unit) related with ISO and ARI guideline were introduced and researched. GSHPs testing was performed by NR GT 101, 102 and analyzed performance factors. Test result, Energy Efficiency Ratio and Coefficient of performance factor of GSHPs were relatively low at an average value rather than Certification.