• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.4
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• pp.31-38
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• 2017

The heating and cooling air conditioning field has been increasing the problems of energy consumption and global warming in the world. A geothermal heat pump has been known as one of the highest efficient heating and cooling system. In this study, the analysis about the test standards of the geothermal heat pump of the Republic of Korea was executed. From the research, the following results were given. It is needed to address the domestic test standard for direct heat exchange geothermal heat pump. Water to air multi geothermal heat pump test standard was only developed in Korea. The test standard to calculate a seasonal energy efficiency ratio for cooling period and heat seasonal performance factor for heating period should be newly developed to estimate actual annual energy consumption and $CO_2$ emission.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.3
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• pp.1-6
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• 2022

Ground source heat pump (GSHP) system is highly efficient and environment-friendly and supplies heating, cooling and hot water to buildings. For an optimal design of the GSHP system, the ground thermal properties should be determined to estimate the heat exchange rate between ground and borehole heat exchangers (BHE) and the system performance during long-term operating periods. However, the process increases the initial cost and construction period, which causes the system to be hindered in distribution. On the other hand, much research has been applied to the artificial neural network (ANN) to solve problems based on data efficiently and stably. This research proposes the predictive performance model utilizing ANN considering local characteristics and weather data for the predictive performance model. The ANN model predicts the entering water temperature (EWT) from the GHEs to the heat pump for the modular GHEs, which were developed to reduce the cost and spatial disadvantages of the vertical-type GHEs. As a result, the temperature error between the data and predicted results was 3.52%. The proposed approach was validated to predict the system performance and EWT of the GSHP system.

• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.33-38
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• 2011

Medicated water electrolysis apparatus, which electrolyzes water into acidic water and alkaline water, was in the spotlight as becoming known the effect of alkaline water. It is known as good for health as removing active oxygen in the human's body and promoting digestion. But, the customers could not get that desired water temperature because these apparatuses are directly connected with a water pipe. So, the cooling system was developed for controlling the temperature of the alkaline water. One of the typical way is to store water in water tank and control the temperature. But, in this way, storing water can be polluted impurities coming from outside. For protecting this pollution, the cooling system based on indirect heat exchange method through phase change between water and ice was developed. In this study, we have calculated efficiency of the cooling system with phase change by experiment and commercial CFD(Computational Fluid Dynamics) code, ANSYS CFX. To consider the effect of latent heat that is generated by melting ice, we have simulated two phase numerical analyses used enthalpy method and found the temperature, velocity, and ice mass distribution for calculating the efficiency of cooling. From the results of numerical analysis, we have obtained the relationship between the cooling efficiency and each design factor.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.409-424
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• 1987

Simulation on the hot water ONDOL heating system was made in order to investigate the variation of room temperature and specific fuel consumption of boiler. Heat balance equation was derived by response factors and solved implicitly. Variation of room temperature and specific fuel consumption of boiler were calculated with respect to the thickness of room floor, the absorptivity of wall for solar radiation, on-off temperature range of boiler and air exchange. The results show that specific fuel consumption of boiler is independent of the thickness of room floor and decreases with increasing the absorptivity of wall and on-off temperature range of boiler. However, it increases with increasing the air exchange. They also show that, when the absorptivity and on-off temperature range of boiler are increased, the amplitudes of room temperature variation increase.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.3
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• pp.282-288
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• 2019

When liquefied natural gas (LNG) is vaporized to form natural gas for industrial and household consumption, a tremendous amount of cold energy is transferred from LNG to seawater as a part of the phase-change process. This heat exchange loop is not only a waste of cold energy, but causes thermal pollution to coastal fishery areas by dumping the cold energy into the sea. This project describes an innovative new design for reclaiming cold energy for use by cold storage warehouses (operating in the 35 to $62^{\circ}C$ range). Conventionally, warehouse cooling is done by mechanical refrigeration systems that consume large amounts of electricity for the maintenance of low temperatures. Here, a closed loop LNG heat exchange system was designed (by simulator) to replace mechanical or vapor-compression refrigeration systems. The software PRO II with PROVISION V9.4 was used to simulate LNG cold energy, gas re-liquefaction, and the vaporized process under various conditions. The effects on sensible and latent heats from changes to the array type of heat exchangers have been investigated, as well as an examination of the optimum.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4047-4051
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• 2014

Modern apartment houses are constructed to be relatively airtight with a high heat insulation system to increase the energy efficiency. Such a system has a range of deleterious effects due to the insufficient ventilation. In this study, the ondol system, which is used as a heat source typical of winter in Korea, was set as the default system to evaluate the indoor heat environment according to the ventilation method, the factors of energy reduction by the ventilation system was analyzed. The experimental apparatus was used to simulate the ambient conditions for a certain constant temperature and humidity chamber. The experimental results showed that the supply water temperature higher air volume decreases with increasing supply air temperature in the following order: floor supply/exhaust > total heat exchange supply/exhaust > forced supply/exhaust. Through this study, the applicability of various ventilations could be examined.

• Journal of Bio-Environment Control
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• v.15 no.3
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• pp.211-216
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• 2006

This study was carried out to investigate the effect of greenhouse cooling by a geothermal heat pump system on greenhouse temperature and growth of vegetable transplants in summer season. Greenhouse air temperature in day time was $3-4^{\circ}C$ lower in fog plus shading system than in shading, while in night time that was $5-7^{\circ}C$ lower in geothermal heat pump (GHP) plus shading system compared to shading or fogplus shading. system. Plant height of cucumber, tomato and hot pepper transplants was shortened in GHP plus shading compared to shading or fog plus shading system. And Leaf area and dry weight were slightly decreased in GHP plus shading compared to the other systems. Therefore, healthy transplant index on cucumber, tomato and hot pepper was higher in GHP plusshading than in shading or fogplusshading system.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.769-775
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• 2008

The objective of this report is to determine the difference of thermal response that grouted two different materials, and compare the simulation result of the length of total ground heat exchanger length that using the ground thermal conductivity. And also to know heat exchange variation of ground heat exchanger temperature that measured with various test depth. The result shows that the test hole grouted with water permeable material got better thermal response than grouted with water impermeable material. However, with consideration of ingnore for the initial 12 hour data, the test hole grouted with impermeable material has larger thermal conductivity than the other. By former thermal conductivity, simulated data by engineering program shows only 3.4% difference or less. This result shows that ground thermal conductivity is not the main variables for the design program of ground heat exchanger. At the cooling or heating mode, base on the depth of -150m, the ground heat exchanger has best temperature at $-90{\sim}-60m$ and than getting worse because of entering water heat exchanged with leaving water in the same hole.

• Journal of Mechanical Science and Technology
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• v.15 no.3
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• pp.357-365
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• 2001

The aim of this paper is to perform the experiment and the numerical simulation for investigating the heat transfer in a regenerator system with ceramic honeycomb and to suggest a useful correlation for optimization of the regenerator system. For achieving this, the effects of some parameters were investigated, e. g., switching time, cell size and length of honeycomb on the mean temperature efficiency. The measured temperatures by R-type thermocouples were compared with the predictions by means of the commercial package, STAR-CD. A useful correlation for thermal efficiency was newly proposed as a function of the normalized switching time, defined in terms of switching time, cell size and length of honeycomb. The results showed that the thermal efficiency is above 90% and the normalized heat exchange rate is higher than 80% when the normalized switching time is less than 1000.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.434-439
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• 2008

Dome stadiums give thermal unpleasant feeling to occupants because of the radiant heat and the indoor and outdoor haet exchange from roogs or lightweight building envelopes of sidewalls. This study analyzed the indoor temperature and velocity distribution according to various air supply and return sustems in dome stadiums in summer.