• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2165-2170
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• 2008

The cooling load in winter season is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Therefore, the development of a multi-heat pump which can cover heating and cooling simultaneously for each indoor unit is required. In this study, the characteristics and performance of a simultaneous heating and cooling heat pump in the cooling-only and cooling-main operating mode was investigated experimentally with a variation of indoor air dry bulb temperature which is from $21^{\circ}C$ to $35^{\circ}C$. EEV opening was adjusted from 20% to 24% during the tests. When the indoor air temperature varied, the performance in the cooling-only mode was more sensitive to the temperature than in the cooling-main mode. The total capacity and COP were increased by 53.8% and 48.1%, respectively, in the cooling-main, while those were increased by 19.6% and 19.3% in the cooling-only mode. The performance differences between the two operating modes became larger at lower temperatures, especially for the COP.

• 설비공학논문집
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• 제20권7호
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• pp.492-499
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• 2008

The cooling load in winter is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a multi-heat pump with 3-piping system was investigated as a function of refrigerant charge and its performance was analyzed in cooling mode, heating mode, and heat recovery mode. COP in the heating or cooling mode showed little dependence on refrigerant charge at overcharge conditions, while those were strongly dependent on refrigerant charge at undercharge conditions and outdoor inlet temperature. In the heat recovery mode, the performance of the system was very sensitive to charge amount at all conditions. Optimum charge amount in the heat recovery mode was 14% lower than that in the cooling mode at the standard condition because the refrigerant only passed the indoor units. It is required to store the excessive refrigerant charge in a storage tank to optimize the system performance at operating modes.

• 설비공학논문집
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• 제24권8호
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• pp.646-655
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• 2012

This study is intended to analyze the thermal performance and evaluate the applicability about non-duct type heat recovery ventilation system integrated with window. Eventually, economic analysis of the system is conducted according to building energy saving ratio of it. As results of the thermal performance, the U-factor of the window conducted on the basis of KS F 2278 appears to $1.8W/m^2K$, and the effective heat exchange efficiency of the ventilator conducted on the basis of KS B 6879 appears 49.95% for cooling, 66.89% for heating. In the applicability evaluated by TRNSYS 16, the caes of applying the heat recovery ventilator integrated with window is found to reduce the cooling or heating load by 2.9% or 13.5% than the non-ventilator case. The results of economic analysis taking a side of consumer is verified as the payback is 3 years, and the accumulated earning is 1,408,133 won in terms of '600,000 won/unit' for initial cost, 10 years for useful life of the system.

• 설비공학논문집
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• 제23권1호
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• pp.32-37
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• 2011

The present study has been conducted to propose an algorithm regarding real-time load estimation of a gas engine-driven heat pump. In the study, thermal load of an indoor unit is estimated in terms of air-side and refrigerant-side. The air-side estimation is based on a typical heat exchanger model and is found to be in good agreement with experimental data. When it comes to the refrigerant-side load, a pressure difference across a valve must be estimated. For the estimation, it is assumed to be proportional to a bigger pressure difference that is available either by measurement or by estimation. Relative good agreement between the air- and refrigerant-sides suggests that the assumption may be plausible for the load estimation. The summed flow rate of all of indoor units is in good agreement with the throughput of the compressor which are calculated from the manufacturer's software. Accordingly, estimated thermal loads are also in good agreement. The proposed algorithm may be further developed for improved control algorithm and fault diagnosis.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.245-250
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• 2008

This study is on the availability of solar thermal energy in Korean high-rise apartment complex depending on the installation type of solar collectors to roof or facade of building. Firstly, solar access evaluation on the roof and the facade of apartment buildings was carried out. The total thermal load of each apartment unit and building was investigated and matched with the energy which was produced by solar thermal systems on the facade. The considered layout patterns of apartment buildings were '一type', 'alternative 一type', 'ㄱtype' and 'ㅁtype' and that was analyzed in prior studies. Extensive dynamic hourly energy simulations with the solar thermal system were Performed with the TRNSYS of SEL. We assumed that the apartment complex is composed of 9 buildings and located in Daejeon. The collectors are the heat-pip evacuated tube collectors and the number of collectors are 45 tubes We assumed that the collectors are installed on the balcony of each unit and the angle of incilnation is $90^{\circ}$. As a result, the supply amount of solar thermal systems is about 4,850,086kJ/hr and the solar fraction is about 66%. The solar fraction according to each azimuth is about 66% on the south, 62% on the south-east $30^{\circ}$ and 56% on the south-east $60^{\circ}$. So, we quantitatively got a line on the optimal azimuth for installing the solar thermal systems. The solar fraction has differences from 5% to 15% of each floor, 6th, 12th and 20th and those tendencies are same in analyzed each 4 types of the apartment complexes.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.53-59
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• 2012

This study was carried out to evaluate thermal performance of the renewable hybrid heat supply system with solar thermal system and wood pellet boiler for Zero Carbon Green home of apartment houses. The hybrid heat supply system was set up at Korea Institute Energy Research in 2011. The system was comprised of the wood pellet boiler unit with heat capacity designed as 20,000kcal/hr, a $0.15m^3$ hot water storage tank for space heating, a evacuated tubular solar collector $3.74m^2$ of aperture area at the $20^{\circ}$ install angle, a $0.3m^3$ hot water storage tank. Thermal performance tests for one-house of apartment house were carried out by hot water load and heating load in winter season through the hybrid heat supply system. As a result, hot water energy supplied by the hybrid heat supply system was 11kWh in a day. Solar thermal energy portion was 2.99kWh which is 27% of the total hot water energy supply. wood pellet boiler supply portion was 8.017kWh which is 73% of the total hot water energy supply.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1996년도 사용종료 매립지의 안정화 에 관한 국제 세미나
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• pp.97-101
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• 1996

Municipal and sanitary landfills can pose environmental problems due to leachate, landfill gas md unstable geotechnical properties. Most governmental bodies delay the correction of landfill problems or landfill replacement until a crises stage is reached. The replacement of a landfill is often made difficult due to costly regulatory controls, public opposition to siting and the high cost of closure for the previous landfill unit. Solutions to extending landfill life and capacity Involve waste minimization by recycling, refuse compaction and waste-to-energy incineration. Incineration can reduce the volume of refuse by 50-95%. The largest installed bases of municipal waste Incinerators are located in Japan and the U.S. The volume of waste contained in a landfill can be estimated by load count tabulations, weight-and-volume measurements or a material balance analysis based on the trash profile of user categories. for an existing landfill, core samples may be collected and analyzed for use in a material balance analysis. Newly generated refuse contains approximately 50% of the heating value of coal. However, landfill properties vary significantly due to the waste profile of the contributors and biodegradation due to time and weathering. The volume of the Nanji-do landfill

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.76-81
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• 2007

The shopping center in underground passage increased for efficient space utilization in urban area. This study describes operation characteristics of all air type and hybrid type with local ventilation and fan coil unit fixed to ceiling. In order to compare energy saving, thermal environment and installation space, etc., integrated simulator with heat production and indoor distribution system is designed and constructed. Energy saving of the hybrid system is calculated as over 30% compared to conventional all air type. And also the results showed that humidity decreased about 6%, also indoor thermal distribution is improved as temperature variation of around $1^{\circ}C$.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.1145-1151
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• 2022

A hybrid cutting using both plasma and end mill was developed for safe and efficient dismantling of nuclear facilities. In this cutting method, a moving arc plasma heats up the workpiece before milling. Thermally softened part of the workpiece is then removed quickly and deeply with an end mill. For the cutting experiments, a three-axis numerical control (NC) milling machine was combined with a commercialized arc plasma torch and used to cut 25 mm thick stainless steel plates. Experimental results revealed that pre-heating by arc plasmas can improve the cutting volume per unit time higher than 40% by reducing the cutting load and increasing the cuttable depth when using an end mill without cutting fluids. These advantages of a hybrid cutting process are expected to contribute to quick and safe segmentations of metal structures with radioactively contaminated inner surfaces.

• KIEAE Journal
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• 제16권3호
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• pp.113-119
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• 2016

Purpose: In this study, we evaluate the annual energy performance of the detached house which was designed with the aim of zero energy. Method: The experimental house which was constructed in Gonju Chungnam in 2013, is the single family detached house of light weight wood frame with $100m^2$ of heating area. Thermal transmittance of roof (by ISO 10211) and building external walls are designed as $0.10W/m^2K$ and $0.14W/m^2$ respectively and low-e coating vacuum window glazing with PVC frame was installed. Also grid connected PV system and natural-circulation solar water heater was applied and 6kWp capacity of photovoltaic module was installed in pitched roof and $5m^2$ of solar collector in vertical wall facing the south. We analyzed the 2014 annual data of the detached house in which residents were actually living, measured though web-based remote monitoring system. Result: First, as a result, total annual energy consumption and energy production (PV generation and solar hot water) are 7,919kWh and 7,689kWh respectively and the rate of energy independence is 97.1% which is almost close to the zero energy. Second, plug load and hot water of energy consumption by category showed the highest numbers each with 33% and 31%, with following space heating 24%, electric cooker 8%, lighting 3% in order. Hot water supply is relatively higher than space heating because high insulation makes it decreased.