• Journal of the Korean Institute of Gas
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• v.10 no.4 s.33
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• pp.34-40
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• 2006

This paper provides a fusion technology between a district cooling energy system and an environment conservation policy based on the energy savings and reusable cold energy resources. The district heating and cooling systems are very effective ways for an energy saving, a cost reduction and a safety control. It is necessary to equalize the energy savings and an environmental preservation policy for an improved human lift. A gasification process of a liquefied natural gas, cooling water from deep seawater and an ice water thermal storage system may produce a cold energy. A district cooling system is used to cool an apartment, office buildings and factory facilities with a cooling energy supply pipeline. LNG cooling energy will switch a conventional air-conditioning system, which is operated by on electrical energy and a Freon refrigerant. Coincident with significant clean energy and operating cost savings, LNG cold energy system owen radical reductions in an air-borne pollutant, $CO_2$ and the release of environmentally harmful refrigerants compared with that of the conventional air-conditioning system. This study provides useful information on the fusion technology of a LNG cold energy usage and energy savings, and environmental conservation.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.42-47
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• 2014

In this paper, the cycle performance analysis for the COP of supercritical heat pump using various refrigerants is presented to offer the basic design data for the operating parameters of the system. The working fluids are R134a, R22, R32, R290, R600, R600a, R1270 and R744. The operating parameters considered in this study include superheating degree of evaporator, temperature of gas cooler inlet and outlet, compressor efficiency and evaporating temperature in the supercritical heat pump system. The main results were summarized as follows : Superheating degree, temperature of gas cooler inlet and outlet, compressor efficiency and evaporating temperature of supercritical heat pump system have an effect on the COP of this system. With a thorough grasp of these effect, it is necessary to design the supercritical heat pump using R134a. And, in comparison of COP of supercritical heat pump using various refrigerants, R32 and R600 is the highest, and R744 is the lowest among other refrigerants. From these results, it is confirmed that the COP of supercritical heat pump using R744 is higher than that using freon refrigerants such as R32 and R134a.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.647-655
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• 2021

The IMO (International Maritime Organization) is discussing the improvement of energy ef iciency of ships in order to reduce greenhouse gas emissions from ships. Currently, by applying an ORC power generation system using waste heat generated from ships, high energy conversion efficiency can be expected from ships. This technology uses an organic medium based on Freon or hydrocarbons as the working fluid, which evaporates at a lower temperature range than water. Through this, it is possible to generate steam (gas) and generate power at a low and low temperature relatively. In this study, the analysis of heat flow between the refrigerant and waste heat in the ORC power generation system, which is an organic Rankine cycle, is analyzed using 3D simulation techniques to determine the temperature change, velocity change, pressure change, and mass change of the fluid flowing of the WHRU (Waste Heat Recovery Unit) inside and the outside the structure. The purpose of this study is to analyze how the mass change affects the structure, and this study analyzed the heat transfer of the heat exchanger from the refrigerant and the exhaust gas of the ship's main engine in the ORC power generation system using this technique.

• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.568-575
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• 2020

Ultrasound has been widely used in various industrial fields. One of challenging application areas is cooling microelectronics. Ultrasonic cooling systems can work with air, argon (Ar) and nitrogen (N₂) instead of conventional refrigerant such as freon gas, which can cause global warming. Furthermore, ultrasonic systems do not have moving parts, thus high durability can be obtained. So it is necessary to develop ultrasonic cooling systems due to environmental issues and durability points. In this paper, the design and fabrication processes are explained. When designing the system, a feasibility test was performed with a prototype cooler. Based on the result, finite element analysis with ANSYS software was performed. The predicted anti-resonance frequency for a piezoelectric actuator was 34.8 kHz, which was in good agreement with the experimental result of 34.6 kHz with 0.6% error. In addition, the predicted anti-resonance frequency for the ultrasonic waveguide was 39.4 kHz, which also agreed well with the experimental value of 39.8 kHz with 1.0% error. Based on these results, the developed ultrasonic waveguide might be applicable in microchip cooling.