• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.588-591
• /
• 2009

Ground source heat pump system; GSHPs is close to most practical use for early stage investment cost and energy efficiency in new renewable energies, and currently considered utilizing to the heat and cooling system of a building. Particularly, the case to utilize 'Standing Column well heat source gathering method' in the open standards process to have the excellent capability of gathering geothermal source is increased. But the research for the optimal design technology and the assessment of a pollution level of the ground to utilize a single well for gathering geothermal is insignificant and the design is insufficient. The heating and cooling system and the equipment to utilize a large size residential development to have over 1000 households have not developed yet. Therefore, our company developed 'geothermal hybrid system' which can construct the heat and cooling system using geothermal energy for a large size residential development of over 1000 households and conducted the evaluation of economic feasibility. Moreover we developed automatic equipment for gathering geothermal source and PLC (Programmable logic controller) to have optimal efficiency and FCU (fan coil unit) considering the floors of large size apartments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.1
• /
• pp.71-81
• /
• 2005

The main objective of the present study is to investigate the performance characteristics of a ground-source heat pump(GSHP) system with a 130 m vertical and 62 mm nominal diameter U-tube ground heat exchanger. In order to evaluate the performance analysis, the ground-source heat pump connected to a test room with $90\;m^2$ floor area in the Korea Institute of Construction $Technology(37^{\circ}39'N,\;126^{\circ}48'E)$ was designed and constructed. This ground-source heat pump system mainly consisted of ground heat exchanger, indoor heat pumps and measuring devices. The cooling and heating loads of the test room were 5.5 and 7.2 kW at design conditions, respectively. The experimental results were obtained from July 2, 2003 to July 1, 2004. The cooling and heating performance coefficients of the system were determined from the measured data. The average cooling and heating COPs for the system were obtained to be 4.90 and 3.96, respectively. The temperature variations in ground and the ground heat exchanger pipe surface at different depths were also measured.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.143.2-143.2
• /
• 2011

Energy foundations and other thermo-active ground structure, energy wells, energy slab, and pavement heating and cooling represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimized maintenance. This paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Pipes, energy slabs, filled with a heat carrier fluid are installed under conventional structural elements, forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and heat sink in summer season. The system represented very high heating and cooling performance due to the stability of EWT from energy slab. Maximum heat pump unit COP and system COP were 4.9 and 4.3.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.14 no.4
• /
• pp.43-52
• /
• 2018

This paper presents the cooling performance analysis results of a ground-source heat pump (GSHP) system using hybrid ground heat exchanger (HGHE). In this paper, the HGHE refers to the ground heat exchanger (GHE) using both a vertical GHE and a surface water heat exchanger (SWHE). In order to evaluate the system performance, we installed monitoring sensors for measuring temperatures and power consumption, and then measured operation data with 4 different load burdened ratios of the hybrid GHE, Mode 1~Mode 4. The measurement results show that the system with HGHE mainly operates in Mode 1 and Mode 2 over the entire measurement period. The average cooling coefficient of performance (COP) for heat pump unit was 5.18, while the system was 2.79. In steady state, the heat pump COP was slightly decreased with an increase of entering source temperature. In addition, the parallel use of SWHE and VGHE was beneficial to the system performance; however, further research are needed to optimize the design data for various load ratios of the HGHE.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.2117-2122
• /
• 2004

The main objective of the present study is to investigate the performance characteristics of a ground source heat pump (GSHP) system with a 130 m vertical 60.5 mm nominal diameter U-bend ground heat exchanger. In order to evaluate the performance analysis, the GSHP system connected to a test room with 90 $m^2$ floor area in the Korea Institute of Construction Technology ($37^{\circ}39'$ N, $126^{\circ}48'$ E) was designed and constructed. This GSHP system mainly consisted of ground heat exchanger, indoor heat pump and measuring devices. The cooling and heating loads of the test room were 5.5 and 7.2 kW at design conditions, respectively. The experimental results were obtained from July to January in cooling and heating season of $2003{\sim}2004$. The cooling and heating performance coefficients of the system were determined from the experimental results. The average cooling and heating COPs for the system were obtained to be 4.82 and 3.02, respectively. The temperature variations in ground and the ground heat exchanger surface at different depths were also measured.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.6
• /
• pp.60-67
• /
• 2012

Government Geothermal Cooling-Heating Projects has made efforts to reduce GHG(Greenhouse Gas) emissions and to manage cost of greenhouse farm households. This study evaluated the economic benefits of heating load rate of change by comparing Geothermal Cooling-Heating System with the existing system(greenhouse diesel heating) in the Government Geothermal Cooling-Heating Projects. Economic analysis results shows that, 1) When installing the Cooling-Heating system according to the ratio of 70% heating load in policy standards, the geothermal cooling-heating system has economic efficiency with greenhouse type or scale independent because the investment cost is recovered within 7 years. And It was more economic efficiency the ratio of 50% heating load than70% heating load. 2) When installing the Cooling-Heating system according to the glass greenhouse of the ratio of 90% heating load, pay period of investment cost is recovered within 5 years. Therefore it is necessary to apply flexible heating sharing according to greenhouse type or scale.

• Journal of the Korean Society of Visualization
• /
• v.16 no.3
• /
• pp.52-58
• /
• 2018

In this study, an experimental facility has been built to measure the cooling performance of a piezoelectric fan. The facility is composed of a heat source made of $50{\mu}m$ Ni-Cr foil, a piezoelectric fan and a rotary fan for cooling the heat source. For two cases where the foil is vertical or horizontal, the surface temperature on the foil has been measured by an IR camera with and without cooling and the cooling performance of both fans has been analyzed. With cooling by both fans, the rotary fan lowers the surface temperature of the foil as a whole, while the piezoelectric fan lowers the surface temperature at the center of the foil locally. It is also found that the cooling effectiveness of the piezoelectric fan is higher on the horizontal foil than on the vertical foil because the natural convection interferes with the jet from the piezoelectric fan.

• The KSFM Journal of Fluid Machinery
• /
• v.15 no.3
• /
• pp.57-63
• /
• 2012

Effects of coolant pre-cooling and fuel pre-heating on the performance of a combined cycle using a F-class gas turbine were investigated. Coolant pre-cooling results in an increase of power output but a decrease in efficiency. Performance variation due to the fuel pre-heating depends on the location of the heat source for the pre-heating in the bottoming cycle (heat recovery steam generator). It was demonstrated that a careful selection of the heat source location would enhance efficiency with a minimal power penalty. The effect of combining the coolant pre-cooling and fuel pre-heating was also investigated. It was found that a favorable combination would yield power augmentation, while efficiency remains close to the reference value.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.390-395
• /
• 2001

Cooling characteristics using convection and conduction heat transfer in a parallel channel with extruding heat sources are studied numerically. A two-dimensional model has been developed for numerical prediction of transient, compressible, viscous, laminar flow, and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve this problem. The considered assembly consists of two channels formed by two covers and one PCB which has three uniform heat source blocks. Five different cooling methods are considered to find efficient cooling method in a given geometry and heat source. The velocity and temperature fields, local temperature distribution along surface of blocks, and the maximum temperature in each block are obtained.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.26 no.5
• /
• pp.212-217
• /
• 2014

Recently, the use of renewable energy has been increased due to growing concern on the energy-saving at buildings and the reduction of $CO_2$ emission. In the field of architecture, to reduce the energy consumption of heating, cooling and hot water supply, heat pump systems with renewable energy has been developed and used in various applications. However, there have been many of researches on the large-scale commercial heat pump systems, but the research and the field application of a compact heat pump system is rare. Therefore, in order to develop the compact heat pump for the small-scale residential building, this study conducted the performance test and feasibility study for a hybrid heat pump using the heat source of air, solar and ground. In the results of experiments through a trial product, the average COP of cooling mode with ground heat source was 4.75, and it of heating mode was 4.03. Furthermore, the average COP of cooling mode with air heat source was 2.60, and it of heating mode was 2.92. Finally, payback period of the system was calculated as 9.2 years.