• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.17-22
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• 2002

A conventional silica gel/water adsorption chiller has been analyzed numerically. A novel non-dimensional mathematical model has been presented to analyze the design effect of different components of an adsorption chiller. The design parameters of this system are characterized by the number of transfer unit, NTU, of different components and the inert material alpha number, ${\alpha}$of different components of the systems. Results show that condenser NTU$\sub$a/ has the most influential effect on the system performance, which is fellowed by absorber NTU$\sub$e/. It is also seen that coefficient of performance (COP) and non-dimensional specific cooling capacity increases with the increase of NTU$\sub$a/ and NTU$\sub$e/, but decreases with the increase of inert material alpha number. A thermo-economic data of the adsorption chiller and some other heat pump systems those are in practical operation are also presented.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.102-108
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• 2007

Heat pump systems are recognized to be heating and cooing systems. In this study, to check the practical application possibility of heat pump systems as low temperature storage systems and get basic data, apples of a long term storage items were stored and performance of low temperature storage and quality changes of apples were evaluated. Cooling coefficient of performance of the system was from 1.1 to 1.3. Although ambient air temperature varied widely from $-13^{\circ}C$ to $29.6^{\circ}C$ during low temperature storage period from January to June, the average temperature of low temperature storage chamber was $1.1^{\circ}C$ at setting temperature of $1.5^{\circ}C$. Sucrose of apples stored by the heat pump decreased from initial sucrose of 15.4% (Brix number) to final sucrose of 14.3%. Weight loss ratio of apples was 9.7% and internal and external view of apples after low temperature storage were very satisfactory with the naked eye.

• Journal of Biosystems Engineering
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• v.32 no.1 s.120
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• pp.20-29
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• 2007

Korean farmers have purchased agricultural dryer and low temperature storage system apart. In this study, the system was designed and constructed to investigate the practical application possibility of the air to air heat pump as drying and low temperature storage system for agricultural products with providing basic data. The performance and drying characteristics of the system evaluated by drying red pepper. The value of coefficient of performance of the system for heating was from 1.8 to 2.2 when ambient air temperature varied from 13$^{\circ}C$ to 23$^{\circ}C$. For operating the heat pump as dryer for drying red pepper by setting three drying air temperature of 50, 55 and 60$^{\circ}C$, specific moisture extraction rates meaning amount of energy consumption for removing moisture of 1kg from red pepper were 1.095, 1.017 and 1.094 kg$_{water}$/kWh, respectively. The drying period up to moisture ratio of 0.02 were 31, 26 and 21 hour, respectively. The lightness, redness, yellowness and chroma differences of red pepper dried by the heat pump dryer were lowered than those of red pepper dried by conventional heated air dryer except for yellowness difference at drying air temperature of 60$^{\circ}C$.

• KIEAE Journal
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• v.15 no.3
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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.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.11-19
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• 2021

In this study, combined heat source heat pump system was implemented with 4 single heat source heat pumps each applied with a geothermal source and a water source. Five cases (Case1~Case5) were configured to conduct a performance comparison and analysis of the combined heat source heat pump system. First of all, as a result of analyzing the heat source, the case when 4 ground heat sources were applied (Case1) showed a uniform EST(Entering Source Temperature) distribution throughout the year since it is less affected by outside air compared to the case when 4 water heat sources were applied (Case5). In both winter and summer, the ground heat source maintained higher EST than the water heat source. Therefore, the system with high ratio of geothermal sources is advantageous for heating, and with high ratio of water heat sources is advantageous for cooling.

• New & Renewable Energy
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• v.19 no.4
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• pp.72-83
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• 2023

Only ground source heat pump units certified according to the regulations in Korea can be adopted in ground source heat pump systems. In this study, domestic and international standards and regulations for ground source heat pump units were investigated. Unlike ISO 13256-1~2, which is the international standard, KS B 8292~8294 for ground source heat pump unit only included rated test conditions. Therefore, it is necessary to supplement various test conditions to the KS B series, because its performance data, which is required to calculate the system's design capacity, is dependent on the change in entering water temperature. The difference between the coefficient of performance of the certified ground source heat pump units and the certified criteria changed significantly according to the operating mode, heat source, and load type, because the criteria increased by about 5% for all. Thus, it is highly suggested that the certification standards be revised while considering the product performance level and various conditions.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.2
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• pp.39-51
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• 2007

Unconsolidated and permeable alluvial deposit composed of sand and gravel is distributed along the fluvial plain at the Iryong study area. Previous studies on the area show that a single alluvial well can produce at least 1,650m3d-1 of bank infilterated shallow groundwater(BIGW) from the deposit. This study is aimed to evaluate and simulate the influence that seasonal variation of water levels and temperatures of the river have an effect on those of BIGW under the pumping condition and also to compare seasonal variation of COPs when indirectly pumped BIGW or directly pumped surface water are used for a water to water heat pump system as an heat source and sink using 3 D flow and heat transport model of Feflow. The result shows that the magnitude influenced to water level of BIGW by fluctuation of river water level in summer and winter is about 48% and 75% of Nakdong river water level separately. Seasonal change of river water temperature is about $23.7^{\circ}C$, on other hand that of BIGW is only $3.8^{\circ}C$. The seasonal temperatures of BIGW are ranged from minimum $14.5^{\circ}C$ in cold winter(January) and maximum $18.3^{\circ}C$ in hot summer(July). It stands for that BIGW is a good source of heat energy for heating and cooling system owing to maintaining quite similar temperature($16^{\circ}C$) of background shallow groundwater. Average COPh in winter time and COPc in summer time of BIGW and surface water are estimated about 3.95, 3.5, and about 6.16 and 4.81 respectively. It clearly indicates that coefficient of performance of heat pump system using BIGW are higher than 12.9% in winter time and 28.1% in summer time in comparision with those of surface water.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.487-499
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• 2014

While the vertical open type of heat exchanger is more effective in areas of abundant groundwater, and is becoming more widely used, the heat exchanger most commonly used in geothermal heating and cooling systems in Korea is the vertical closed loop type. In this study, we performed numerical simulations of the optimal utilization of geothermal energy based on the hydrogeological and thermal properties to evaluate the efficiency of the vertical open type in areas of abundant groundwater supply. The first simulation indicated that the vertical open type using groundwater directly is more efficient than the vertical closed loop type in areas of abundant groundwater. Furthermore, a doublet system with separated injection and extraction wells was more efficient because the temperature difference (${\Delta}$) between the injection and extraction water generated by heat exchange with the ground is large. In the second simulation, we performed additional numerical simulations of the optimal utilization of geothermal energy that incorporated heat transfer, distance, flow rate, and groundwater hydraulic gradient targeting a single well, SCW (standing column well), and doublet. We present a flow diagram that can be used to select the optimal type of heat exchanger based on these simulation results. The results of this study indicate that it is necessary to examine the adequacy of the geothermal energy utilization system based on the hydrogeological and thermal properties of the area concerned, and also on a review of the COP (coefficient of performance) of the geothermal heating and cooling system.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.324-331
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• 2013

All evacuated tube collector is being constantly studied since it can reduce the conductive heat loss in absorber by using vacuum technology and has advantage of heat transport capacity and quick thermal response in comparatively small temperature difference. This study investigated the dynamic thermal performance of the solar collector with the control condition of solar irradiance and fluid temperature by using performance experimental apparatus which is combined with solar collector and refrigerator, examined the thermal characteristics in definite temperature range of fluid in constant temperature tank by simultaneously measuring refrigerating performance. As a result of it, I deducted the related equation of collector efficiency and found that mean collector efficiency has increased through quick heat transfer characteristics according to increase of outdoor temperature and irradiance in case of outlet temperature of constant temperature tank $22^{\circ}C$ when set outlet temperature of solar collector $25^{\circ}C$ with outlet temperature of constant temperature tank $18^{\circ}C$ & $22^{\circ}C$. Also COP of refrigerator was acquired value of 6.2~7.1 at outlet temperature of constant temperature tank $18^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.3
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• pp.258-266
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• 2000

Experimental investigation and cycle simulation of a capacity modulation of a heat pump system using a hydrofluorocarbon (HFC) refrigerant mixture, R32/134a as an alternative to R22, have been done. In the cycle simulation, the refrigeration system was operated by assigning the temperatures of the external heat transfer fluids with the heat exchangers generalized by an average effective temperature difference. Heating capacity, cooling capacity, and coefficient of performance (COP) of the system were investigated at several operating conditions. Experimental apparatus which had a refrigeration part and a composition changing part was built, and the performance of the heat pump system filled with R32/134a mixture was investigated. A gas-liquid separator was used in the experiment to change the composition by collecting the vapor and the liquid Phase separately, The mass fraction of the charged refrigerant in the heat pump system was 40/60 and 70/30 by weight percentage. The composition of the refrigerant with initial composition of 40/60 varied from 29/71 to 41/59 in the refrigeration cycle. For the refrigerant with initial composition of 70/30, the composition varied from 65/35 to 75/25.