• 제목/요약/키워드: Long-term Heat Load

검색결과 44건 처리시간 0.031초

Cooling Performance Test of the KEPCO HTS Power Cable

  • Yang, H.S.;Kim, D.L.;Sohn, S.H.;Lim, J.H.;Choi, H.O.;Choi, Y.S.;Ryoo, H.S.;Hwang, S.D.
    • 한국초전도ㆍ저온공학회논문지
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    • 제11권2호
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    • pp.41-43
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    • 2009
  • The HTS power cable system of 3-phase 100-m class has been tested at the KEPCO's Gochang power testing center in Korea during 8,000 hours or more for investigating long-term operating performance. The system is rated 22.9kV, 1250A and is cooled with sub cooled liquid nitrogen. Several cooling performance tests such as cooling capacity, heat load, AC loss, temperature stability and thermal cycle were performed at operating temperature of 66.4K and several different temperatures.

장기내구성을 고려한 EPS의 현장 적용성 (Application of EPS Considering Long-term Durability)

  • 천병식;정창희;안진현
    • 한국지반환경공학회 논문집
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    • 제8권6호
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    • pp.53-60
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    • 2007
  • EPS는 일반적으로 블록형태로 제조되어 토목공사에 이용되고 있으며, 재료특성상 초경량성 및 내압축성을 가지며 자립안정성이 우수하므로 연약지반상 성토재로 적용한 경우 침하 및 측방유동에 대한 대책공법으로 적용되고 있다. 현재 국내에서는 보온 재료로서의 시험 방법 및 품질 규정만이 KS에 규정되어 있고, 공학적 성토 재료로서 활용하기 위한 기준이 확립되어 있지 않다. 따라서 도로공사의 시험시공 및 제조사의 품질시험을 통하여 EPS 설계 기준을 마련하여 적용하고 있는데, 이것들은 주로 재료의 공장제품 즉, 새 제품에 국한되어 연구가 이루어져 왔다. 본 연구에서는 EPS 장기내구성에 주안점을 두어 교대측방유동 대책공법으로 EPS가 적용된 시공현장에서 채취한 EPS시료와 공장제품에 대해 반복재하시험, 동결융해시험, 흡수율시험 등을 통하여 공학적인 장기내구성을 비교 분석하였다. 그 결과 일축압축시험은 채취시료가 공장제품에 비해서 강도가 다소 작게 나타났으며, 삼축압축시험에서 채취시료와 공장제품 모두 일축압축 시험결과에서와 같이 구속응력은 축방향 변형량에 선형비례하는 경향을 나타내었으며, 응력-변형률 관계곡선의 양상은 구속압과 상관없이 유사함을 알 수 있었다.

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시뮬레이션을 통한 지열 히트펌프 시스템과 VRF 시스템의 에너지 성능비교 (Comparison of Energy Performance between Ground-Source Heat Pump System and Variable Refrigerant Flow(VRF) Systems using Simulation)

  • 손병후;임효재;강성재
    • 한국지열·수열에너지학회논문집
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    • 제17권3호
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    • pp.30-40
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    • 2021
  • This paper compares the annual energy performance of four different types of air-conditioning systems in a medium-sized office building. Chiller and boiler, air-cooled VRF, ground-source VRF, and ground-source heat pump systems were selected as the systems to be compared. Specifically, the energy performance of the GSHP system and the ground-source VRF system were compared with each other and also with conventional HVAC systems including the chiller and boiler system and air-cooled VRF system. In order to evaluate and compare the energy performances of four systems for the office building, EnergyPlus, a whole-building energy simulation program, was used. The EnergyPlus simulation results show that both the GSHP and the ground-source VRF systems not only save more energy than the other two systems but also significantly reduce the electric peak demand. These make the GSHP and the VRF systems more desirable energy-efficient HVAC technologies for the utility companies and their clients. It is necessary to analyze the impact of partial load performance of ground-source heat pump and ground-source VRF on the long-term (more than 20 years) performance of ground heat exchangers and entire systems.

고강도 CFT용 콘크리트의 현장적용성 평가 및 장기거동 예측 (A Evaluation on the Field Application of High Strength Concrete for CFT Column)

  • 박제영;정경수;김우재;이종인;김용민
    • 콘크리트학회논문집
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    • 제26권6호
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    • pp.707-714
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    • 2014
  • 콘크리트 충전강관(CFT)은 강관의 내부에 콘크리트로 채워진 기둥이다. CFT는 강재와 콘크리트로 구성되며, 강재는 콘크리트를 내부에서 구속시켰고, 내부 콘크리트는 기둥의 압축하중을 감당한다. 본 실험에서 73~100MPa급 고강도 콘크리트에 관해 유동성실험, 압축강도실험, 압송압력실험을 실시하였으며, CFT용 고강도 콘크리트의 물리적 성질을 알아보기 위해 슬럼프, 슬럼프 플로우, 공기량, U-box시험, O-Lot시험, L-flow시험이 진행되었다. 이러한 연구의 결과를 바탕으로 Mock-up테스트에서 콘크리트 충전성 시험, 수화열 측정 시험, 응력계측 시험을 수행하였다. 현장적용은 상암동 및 서강대 현장의 두 곳에 각각 ${\Box}-566{\times}566{\times}10$, ${\Box}-400{\times}400{\times}25$의 대상기둥을 선정하여 현장계측을 진행하였다. CFT기둥의 장기거동 예측에 관하여 설계하중에 대해 콘크리트의 탄성변형과 건조수축, 크리프 수축을 고려한 ACI 209 재료모델을 사용한 결과는 계측결과와 거의 일치하였다.

태양열 실증시스템의 진공관형 태양열 집열기 장기 열성능 (Long-term thermal performance of evacuated tubular solar collector for demonstration system)

  • 이호;주홍진;윤응상;김상진;곽희열
    • 한국태양에너지학회:학술대회논문집
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    • 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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    • pp.104-110
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    • 2008
  • This paper presents demonstration study results derived through field testing of a part load solar energized cooling system for the library of a cultural center building located in Gwangju, Korea. First operating demonstration system was set up in Gwangju in 2005. These system comprises the $200m^2$ evacuated tubular solar collector, a $6m^3$ heat storage tank. In a 2006, daily average of insolation showed about $506W/m^2$, the solar collector efficiency was 44%. In a 2007, daily average of insolation showed about$507W/m^2$, the solar collector efficiency was 42%. As a result, evacuated tubular solar collector kept the high efficiency for two years.

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태양열 온실 난방에 대한 최척 집열 면적과 경제성 평가 (Optimum Collector Area and Economic Evaluation for the Greenhouse Heating)

  • 박이동;김규인
    • 태양에너지
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    • 제2권1호
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    • pp.49-58
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    • 1982
  • Aim of this study was to obtain the heating performance and the economic evaluation on solar heating system for greenhouse which area of floor was $90m^2$. For heating performance effective solar energy for the greenhouse was compared with overall heating loads including coefficient of heat transfer and conduction. And the economic evaluation solar heating system was evaluated by comparison its initial investiment costing with oil saving cost. Initial investiment costing included collector cost, storage cost, piping cost, control system cost and miscellaneous costs which included pumps, motors etc. The contents of this study included the survey of climate conditions for solar heating, long-term collector performance and optimum collector area of solar heating system in existing greenhouse. The results are follows: 1. Average horizontal radiation during winter was $2,434Kcal/m^2$ day which was the highest value in this country, so the climate conditions of Suwon was suitable for solar heating. 2. Resulting calculation of the optimum collector area was $30m^2$ and the solar energy accounted for 30% of the overall heating load. 3. The capacity of storage tank required 60 liter per unit area ($m^2$) of solar collector.

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회전축 부하를 고려한 BLDC 모터의 열적 특성에 관한 실험 및 수치 해석적 연구 (Thermal Characteristics of 600 W Brushless DC Motor under Axial Loading Condition)

  • 권화빈;이원식;김규탁;박희성
    • 한국정밀공학회지
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    • 제33권12호
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    • pp.999-1005
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    • 2016
  • A brushless direct current (BLDC) motor electronically performs rectification without brushes. It therefore does not have the typical mechanical friction contacts between the brushes and commutators. The BLDC motor has the advantages of high speed, low noise, and electronic noise reduction in addition to high durability and reliability. Therefore, it is mainly used in electric vehicles and electric equipment. However, iron loss and copper loss due to long-term use induce temperature increases in the motor, which reduces its performance and life. The temperatures of the stator and permanent magnet are predicted to be $62.3^{\circ}C$ and $32.2^{\circ}C$, respectively. This study shows the enhanced temperature distribution in a 600 W BLDC motor using unsteady and three-dimensional (3D) numerical investigations validated with experimental data.

설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제29권6호
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제26권12호
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

다 채널 직결 온도측정 시스템의 설계 및 제작 (Development of Multichannel On-line Thermometry System)

  • 신세원;신현진;김명세;김성규
    • Journal of Yeungnam Medical Science
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    • 제16권2호
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    • pp.193-199
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    • 1999
  • 저자들은 다양한 진료 환경과 연구 수행에 폭 넓게 이용할 수 있는 새로운 온도측정 시스템을 개발하기 위하여 임상에서 필요한 기능과 연구에 요구되는 기능을 가진 간편하고 편리한 온도측정 시스템을 개발하였다. 이 측정 시스템은 일정한 지점의 온도를 정확하고 신속하게 측정하여 기록할 수 있는 장치로서 실용 가능성을 다양하게 검증해 본 결과 기존의 평면적인 열 분포도보다 진보된 등온곡선을 도출할 수 있었으며, 기존의 체온 측정장치보다 더욱 편리하게 진료의 각 분야에 효과적으로 이용할 수 있음을 확인하였다. 본 연구결과에 의한 기대효과 및 향후 활용방안으로는 1) 환자의 체온 변화를 신속하게 진단할 수 있어서 치료효과의 극대화와 부작용의 최소화에 기여할 수 있다. 2) 체온의 변화를 일으키는 다양한 질환의 진단 및 치료성과 판정에 이용할 수 있다. 3) phantom을 이용한 다양한 실험적 연구를 수행할 수 있다. 4) 장기 입원중인 환자들을 대상으로 중앙통제 방식으로 환자들의 상태를 지속적으로 감시할 수 있어서 간호인력의 노동력 절약에 많은 도움을 줄 수 있다. 5) 현재의 기능을 더욱 발전시키면 다양한 질환의 환자들에게 두루 적용할 수 있으며, 환자 감시체제를 위한 필수장비로 이용할 수도 있다.

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