• 제목/요약/키워드: Low Temperature Heat Source

검색결과 280건 처리시간 0.024초

세상에서 가장 얇은 그래핀 발광 소자 (The World's Thinnest Graphene Light Source)

  • 김영덕
    • 진공이야기
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    • 제4권3호
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    • pp.16-20
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    • 2017
  • Graphene has emerged as a promising material for optoelectronic applications including as ultrafast and broadband photodetector, optical modulator, and nonlinear photonic devices. Graphene based devices have shown the feasibility of ultrafast signal processing for required for photonic integrated circuits. However, on-chip monolithic nanoscale light source has remained challenges. Graphene's high current density, thermal stability, low heat capacity and non-equilibrium of electron and lattice temperature properties suggest that graphene as promising thermal light source. Early efforts showed infrared thermal radiation from substrate supported graphene device, with temperature limited due to significant cooling to substrate. The recent demonstration of bright visible light emission from suspended graphene achieve temperature up to ~3000 K and increase efficiency by reducing the heat dissipation and electron scattering. The world's thinnest graphene light source provides a promising path for on-chip light source for optical communication and next-generation display module.

저온 지열발전의 출력 극대화를 위한 흡수식 동력 사이클의 시뮬레이션 (Simulation of an Absorption Power Cycle for Maximizing the Power Output of Low-Temperature Geothermal Power Generation)

  • 백영진;김민성;장기창;이영수;윤형기
    • 대한기계학회논문집B
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    • 제34권2호
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    • pp.145-151
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    • 2010
  • 본 연구에서는 지열발전 등과 같은 저온 열원을 에너지원으로 하는 발전에 응용될 수 있는 흡수식 동력 사이클의 출력 최적화를 수행하였다. 이를 위해 정상상태 사이클 시뮬레이션을 수행하여 사이클의 성능을 고찰하였다. 시뮬레이션은 열원과 열침의 입구온도 및 유량을 고정한 상태에서 수행하였으며, 일반적인 발전소의 열원-열침 유량비를 고려하였다. 사이클의 성능은 두 개의 독립변수를 이용하여 나타내었는데, 이는 분리기 입구 암모니아 농도와 터빈 입구 압력이다. 시뮬레이션 결과, $100^{\circ}C$의 지열수와 $20^{\circ}C$의 냉각수(지열수 유량의 5배) 조건에서, 흡수식 동력 사이클을 이용하면 지열수 유량 1 kg/s 당 최대 약 14 kW의 출력을 얻을 수 있음을 보였다.

에너지 수요처의 사용특성에 따른 태양열 급탕시스템의 효율분석 (Analysis of Efficiency of Solar Hot Water System based on Energy Demand)

  • 전용준;박경순
    • 한국태양에너지학회 논문집
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    • 제37권5호
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    • pp.39-47
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    • 2017
  • In a hot water system using solar energy, solar heat is not simply collected by the heat collecting plate, but by heat exchange between the solar collector (flat or vacuum type) and the hot water storage tank. Therefore, the amount of collected solar energy depends on the hot water usage patterns that determine the temperature of the thermal storage tank. Also, if the temperature of the hot water stored in the storage tank exceeds the dangerous temperature during the summer, the heat must be released for safety. If the temperature of the hot water in the storage tank is low, it is necessary to heat by the auxiliary heat source. In this study, three buildings are defined as hotel, swimming pool, and school facilities. And we calculated the released heat energy, auxiliary heat source, and pure storage heat energy based on different hot water usage patterns and installation angle of the solar collectors.

저온 열원과 LNG 냉열을 이용하는 암모니아-물 동력 사이클의 열역학적 성능 해석 (Thermodynamic Performance Analysis of Ammonia-Water Power Generation System Using Low-temperature Heat Source and Liquefied Natural Gas Cold Energy)

  • 김경훈;김경천
    • 대한기계학회논문집B
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    • 제38권6호
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    • pp.483-491
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    • 2014
  • 본 연구에서는 현열 형태의 저온 열원과 LNG의 냉열을 이용하는 복합 동력 생산시스템에 대한 열역학적 성능 해석을 수행하였다. 시스템의 작동유체로서 암모니아-물의 비공비 혼합물을 고려하였으며 재생기가 없는 기본 사이클과 있는 재생 사이클의 경우를 비교 해석하였다. 작동유체의 암모니아 농도나 응축 온도에 따라 시스템의 순생산일, 엑서지 파괴, 열효율이나 엑서지 효율 등에 미치는 다양한 영향에 대해 분석하고 논의하였다. 해석 결과는 시스템의 성능 특성이 작동유체의 암모니아 농도나 응축 온도에 따라 민감하게 변화하며, 열원유체 단위질량당 순생산일은 기본 사이클이 유리하나 열효율이나 엑서지 효율은 재생 사이클이 유리하다는 사실을 보여준다.

저온 열원으로부터 최대 동력을 생산하기 위한 유기랭킨사이클(ORC)에 관한 연구 (Study on Organic Rankine Cycle (ORC) for Maximum Power Extraction from Low-Temperature Energy Source)

  • 김경훈;한철호;김기만
    • 한국태양에너지학회 논문집
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    • 제31권3호
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    • pp.73-79
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    • 2011
  • ORC(organic Rankine cycle) has potential of reducing consumption of fossil fuels and has many favorable characteristics to exploit low-temperature heat sources. This work analyzes performance of ORC with superheating using low-temperature energy sources in the form of sensible energy. Maximum mass flow rate of a working fluid relative to that of a source fluid is considerd to extract maximum power from the sources. Working fluids of R134a, $iC_4H_{10}$ and $C_6C_6$, and source temperatures of $120^{\circ}C$, $200^{\circ}C$ and $300^{\circ}C$ are considered in this work. Results show that for a fixed source temperature thermal efficiency increases with evaporating temperaure, however net work per unit mass of source fluid has a maximum with respect to the evaporating temperature in the range of low source temperature. Results also show that the maximum power extraction is possible with R134a for the source temperature of $120^{\circ}C$, with $iC_4H_{10}$ for $200^{\circ}C$, and with $C_6C_6$ for $300^{\circ}C$.

저공해 중소형 디젤차량 히트펌프 제어 (Control of Heat Pump for Low Emission Diesel Engine)

  • 박병덕;이원석;원종필;권순익
    • 한국산업융합학회 논문집
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    • 제5권4호
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    • pp.379-384
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    • 2002
  • As automotive diesel engines adopt the direct injection method for a lower level of the exhaust emission and a higher fuel efficiency, the maximum temperature of engine coolant decreases. Consequently, the total available heat source from the engine coolant decreases over 35%. However, the heating source of air-conditioning system in automobiles depends on the hot engine coolant completely, so that it is nearly impossible to control air conditioning in heating season. Therefore, the present study has been carried out to develop the air conditioning system for the high efficient heat pump type using the HFC-134a. Especially, the air conditioning system of heating has been developed at a beginning stage, when it has low heat source from small and medium sized diesel recreation vehicles. To develop a control logic system for air conditioning system which is a heat pump type with a heat recovery exchanger, its cycle characteristics has been investigated according to the opening of LEV at a bench system.

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히트펌프 시스템의 시설원예 적용에 관한 실험적 연구 (An Experimental Study on Applying Heat Pump System to Facility Horticulture House)

  • 김재돌
    • 동력기계공학회지
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    • 제17권6호
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    • pp.88-94
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    • 2013
  • As the results of analysis that are applying a heat pump using underground water as heat source of facility horticulture house, temperature change in house, growth of cultivated plants and the crop characteristic, the conclusion can be acquired as follows. It was possible to maintain the chamber temperature through operating heat pump with setting goal temperature at $16^{\circ}C$ and temperature variation at ${\pm}3^{\circ}C$. And cooling and heating coefficient of performance in heat pump system are different from setting room temperature and operation condition of equipment, totally in case that the setting temperature in house is low, the coefficient of performance and the in case that temperature departure is low. In case that the house does not heated, the result of the growth characteristic of cucumber planted last 50days is that cucumber grown in house equipped with heat pump is the most favorable growth characteristic due to maintaining a constant room temperature. After 90 days, the quantity and weight cucumber harvested in each house are averagely 9.8%, 13.1% increase and more heavy weight respectively. So it is researched that crop characteristic is superior.

히트펌프식 냉난방장치의 철도차량 적용에 관한 연구 (A study on the application Heat Pump to Rolling Stock Air conditioner)

  • 권태균;송영정;정광무
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2008년도 추계학술대회 논문집
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    • pp.1689-1696
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    • 2008
  • Heat pumps transfer heat by circulating a substance called a refrigerant through a cycle of evaporation and condensation. But Heat pumps system by only using heat-source is not efficient. Because the mean temperature of North Korean winter season is low, economy of air heat-source heat pump descend. This paper is practiced the simulation on evaluation criteria for Heat pump heating and cooling systems to Rolling Stock. Efficiency of the heat pump in order improving from certainly the development of the technique will be able to prevent a freezing actual condition must proceed. As a result, Below $-10^{\circ}C$ used heating and cooling systems of heat pump format even in cold winter season and is serviceable confirmed with heat source supply circle of the Rolling Stock.

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저온수열원이용 열펌프시스템의 전처리 및 성능분석 (Performance Analysis and Prior-Treatment of Heat Pump System with Low-Temperature Water Heat Source)

  • 박성룡;장기창;이상남;라호상;박준택
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.258-263
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    • 2000
  • River water is higher in temperature than the surrounding environment during the winter. It is highly suitable a heat source for heat pump system. Despite its suitability, however, it is not widely used, due to its fouling and corrosive nature in heat exchanger tubes of evaporator. It is designed prior-treatment system which come into direct contact with the river water, such as auto-seamer, ozone generator for bactericidal test and auto-cleaning system. And it is analyzed treatment effects for its operation. It is designed two-stage compression heat pump system using R-134a with heating load 35.16kW, ad analyzed its performance. As a result it is obtained 3.08 COP when mid-point pressure is 1,200kPa, and bypass ratio of flowing refreigerant to high-stage compressor is 25.1%

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숙박업소 건물의 히트펌프 냉난방 시스템 적용을 위한 시뮬레이션 연구 (Study on the Simulation of Heat Pump Heating and Cooling Systems to Resident Building)

  • 최영돈;한성호;조성환;김주성;엄철준
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2006년도 하계학술발표대회 논문집
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    • pp.915-920
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    • 2006
  • Recently available heat pump system by using air heat-source is not efficient. Because the mean temperature of korean winter season is low, economy of air heat-source heat pump descend, and COP is below 3.0. This paper was practiced the simulation on evaluation criteria for heat pump heating and cooling systems to resident building. As a result, heating and cooling composition heat pump system apply to the building needed to be provided heat source for 24 hours.

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