• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.8-17
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• 2016

While greenhouses have been utilized as a sustainable alternative to traditional soil farming, they are often powered by diesel boilers that necessitate vast amounts of non-renewable energy and emit toxic fumes. Thus, geothermal heat pumps have been proposed as a more energy-efficient substitution for diesel boilers. Currently, most horticultural facilities in the United States use shallow geothermal systems, and are often equipped with horizontal underground heat exchangers as well as heat pump equipment. These shallow geothermal systems require a large drilling site and heat pump to function, which results in high maintenance costs. The heat pump itself consumes a large amount of power, which degrades system performance. Conversely, high temperatures can be attained within a single borehole in deep geothermal vertical closing systems without using a heat pump. This setup can dramatically reduce the power consumption and improve system performance. In this study, we have modeled a circulation simulator after the circulation systems in deep geothermal facilities to analyze a 2000-meter borehole in Naju-Sanpo-myeon. The simulator is operated by manipulating various putative parameters affecting system performance to analyze the system's coefficient of performance.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.4
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• pp.53-60
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• 2018

This study was conducted for analysis of a heat pump system using waste heat in an enclosed space such as a green house. The model was developed with mathematical equations in literature and Engineering Equation Solver (EES) was used to get the solution of the developed equations. The simulation results have 5% of reliability comparing the results with actual test data of heat pump system's dynamic operation. The operating performance of the system was calculated with variation of working fluid temperature in the thermal storage tank such as $25^{\circ}C$, $35^{\circ}C$, $45^{\circ}C$ and $55^{\circ}C$. As a result, the system's the highest total heating capacity shows 280 kWh and the storage tank's operating time decreased as the starting storage tank's temperature was high.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.172.1-172.1
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• 2010

In Jeju, underground air is used for heating greenhouse and fertilizing natural $CO_2$ gas by suppling directly into greenhouse. But greenhouse heating method by direct supply of underground air has several problems as like low temperature below $20^{\circ}C$ or high relative humidity over 90%. The underground air is inadequate in heating of crops such as mangos, oranges with the growing temperature over $20^{\circ}C$. Also if the relative humidity of greenhouse is kept with over 90%, diseases can strike almost of the crops. And also the ventilation loss becomes larger because the air pressure of inside greenhouse by direct supply of underground air is higher. In this study the heat pump system using underground air as heat source was developed and heating performance of the system was analyzed. Heating COP of the system was 2.5~5.0 and rejecting heat into greenhouse and extracting heat from underground air in this heat pump system were 46.5~31.4 kW, 34.9~20.9 kW respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.422-425
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• 2009

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.39-46
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• 2005

The present study concerns an experimental study of a R-22 heat pump system consisted of liquid and liquid heat exchangers. The test was performed for various systems of a single-, tandem-, and two stage-cycle at the same environmental conditions of temperature. Various experiments of the heat pump system were peformed to compare the heating capacity and COP, when the outdoor temperature is near $-15^{\circ}C$ and the indoor temperature is $20^{\circ}C.$ As the results of the present study, the system of Tandem(parallel) cycle showed the best heating performance, while the discharge temperature of refrigerant was too high. In case of the system of two stage cycle, the performance characteristics were significantly improved by employing the inter cooler.

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.79-104
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• 2018

A detailed literature review is presented for the applications of the heat pump technologies on the electric vehicles Heating, Ventilation and Air Conditioning (HVAC) system. Due to legal regulations, automotive manufacturers have to produce more efficient and low carbon emission vehicles. Electric vehicles can be provided these requirements but the battery technologies and energy managements systems are still developing considering battery life and vehicle range. On the other hand, energy consumption for HVAC units has an important role on the energy management of these vehicles. Moreover, the energy requirement of HVAC processes for different environmental conditions are significantly affect the total energy consumption of these vehicles. For the heating process, the coolant of internal combustion (IC) engine can be utilized but in electric vehicles, we have not got any adequate waste heat source for this process. The heat pump technology is one of the alternative choices for the industry due to having high coefficient of performance (COP), but these systems have some disadvantages which can be improved with the other technologies. In this study, a literature review is performed considering alternative refrigerants, performance characteristics of different heat pump systems for electric vehicles and thermal management systems of electric vehicles.

• Journal of the Korean Solar Energy Society
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• v.39 no.1
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• pp.67-76
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• 2019

A ground source heat pump (GSHP) system can stable system operation by using underground heat source and has high reliability for energy production. However, wide-spread of the GSHP system is delayed to high initial investment costs. In previous studies, horizontal and unit-type ground heat exchanger (GHX) have developed to overcome disadvantages such as high initial cost. However, these performances of GHXs are greatly influenced by climate and weather conditions. It is necessary to analyze the performance of GHX according to the ground temperature change in the installation site. In this study, the ground temperature of each installation site confirmed and performance of unit-type GHX quantitatively analyzed by numerical analysis. As the result, the performance of the unit type GHX was 33.9 W/m in Seoul, 34.2 W/m in Daejeon, and 37.2 W/m in Busan.The result showed the difference performance of GHX according to local climate was maximum of 9.7%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6053-6059
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• 2013

Heat pumps have attracted considerable attention as a green energy system because they use renewable energy, such as geothermal, solar energy and waste heat, and can have a low electricity consumption rate compared to other conventional electric heating system. Many studies of high efficient heat pump system design was performed previously,but it is not easy to find any an analytical model that consists of components (e.g. compressor, heat exchangers, and expansion valve), not only having an interrelation and interconnection each other but also being flexible to any change in geometry and operating parameters. In this study, a computational model was developed for a heat pump with warm air as a heat source using the one-dimensional modeling software, AMESim. In combination with an independently-developed analytical model for a scroll compressor, the heat pump model can simulate the physical characteristics and actual behavior of the heat pump precisely. In addition, the reliability of the model was improved by verifying the simulation results using experimental data. The simulation data fell into the 10% error range compared with the experimental data. The heat pump model can be used for system optimization studies of product development and applied to other applications in a range of industrial field.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.814-820
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• 2014

Due to the development of human civilization, industrialization and urbanization, the human race demanded the food, clothing and shelter as well as a comfortable living environment. For the purpose of this, the refrigeration and air conditioning part was carried out research and development. However, high oil prices and environmental pollution having problems in the 21st century cannot be overlooked. As an alternative, thermal system was designed using the heat pump to applied sea water heat source. In this paper, outside and sea temperatures are analysed in 2010 and carried out the performance analysis simulation at All water and All Air heat pump system by HYSYS program for domestic use. As a result, total average COP of the system is 3.37 from All Water system and All Air is 3.48. It showed that high performance confirmed in both system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.4
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• pp.31-38
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• 2020

The investment in the technology of using a combined heat source is insufficient, which utilizes the advantages of various heat sources to maximize the potential energy and at the same time increases the performance of the heat pump. In this study, as basic data for the development of a high-efficiency hybrid heat pump system that actively connects and uses various heat sources, simulations were conducted for the heat pumps in two cases where geothermal and hydrothermal heat were applied respectively. In May, COP increased by about 27.3% compared to geothermal heat. In February, the COP percentage decrease of hydrothermal heat compared to geothermal heat is -6.9%. In May, total energy consumption can be reduced by 21.1% when hydrothermal is applied compared to geothermal heat. In February, the total energy consumption increases by 3.4%.