• 제목/요약/키워드: Thermal Emission

검색결과 1,367건 처리시간 0.026초

Numerical Calculation Study on the Generalized Electron Emission Phenomenon

  • Kim, Hee-Tae;Yu, Soon-Jae
    • Journal of Information Display
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    • 제10권4호
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    • pp.158-163
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    • 2009
  • There are two kinds of well-known electron emissions from metal: field and thermionic emission. For thermionic emission, electrons come out of a metal due to the thermal energy, whereas for field emission, electrons tunnel out of a metal through the strong electric field. In this study, the most general electron emission caused by the temperature and electric field with a free electron gas model was considered. The total current density of electron emission comes from the field emission effect, where the electron energy is lower than vacuum, and from the thermionic-emission effect, where the electron energy is higher than vacuum. The total current density of electron emission is shown as a function of the temperature for a constant electric field, and as a function of the electric field for a constant temperature.

합성가스 스파크점화 과급 엔진에서 희박 연소를 통한 열효율 및 배기 개선 (Improvement of Thermal Efficiency and Emission by Lean Combustion in a Boosted Spark-Ignition Engine Fueled with Syngas)

  • 박현욱;이준순;나랑후 잠스랑;오승묵;김창업;이용규;강건용
    • 한국분무공학회지
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    • 제26권1호
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    • pp.40-48
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    • 2021
  • Lean combustion was applied to improve the thermal efficiency and emission in a single-cylinder, spark-ignition engine fueled with syngas. Under naturally aspirated conditions, the lean combustion significantly improved the thermal efficiency compared to the stoichiometric combustion, mainly due to the reduction in heat transfer loss. Intake air boost was applied to compensate the low power output of the lean combustion. The gross indicated power of 24.8 kW was achieved by increasing the intake pressure up to 1.6 bar at excess air ratio of 2.2. The nitrogen oxides showed near zero level, but the carbon monoxide emission was significant.

가스터빈 날개용 경사기능재료의 열충격 특성 (Thermal shock characteristics of FGM for gas turbine blade)

  • 임재규;송준희;김연직
    • 대한기계학회논문집A
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    • 제22권1호
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    • pp.73-79
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    • 1998
  • The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.

성능시험 결과를 이용한 D발전소의 $CO_2$ 대기배출량 계산 ($CO_2$ Emission Calculation of D Thermal Power Plant using Performance Test Results)

  • 문홍규;이상중
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2007년도 추계학술대회 논문집
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    • pp.341-344
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    • 2007
  • 교토의정서(Kyoto Protocol)는 1997년 일본 교토에서 채택되어 2005년 2월에 공식 발효되었다. 우리나라는 현재 온실가스 감축의무 부담이 없지만 2013년부터 감축의무가 거의 확실시되고 있는 상황이다 국내 온실가스 배출량의 25%를 차지하는 발전산업은 화석연료를 사용하고 있어 전력생산에 따른 $CO_2$ 배출량의 계산은 매우 중요한 일이 되었다. 본 논문은 - D발전소의 성능시험에 대하여 기술하고, - 성능시험 결과 얻어진 D발전소 성능시험 Data a, b, c 특성계수를 이용, LNG와 중유 연소시 각각 연료소모량에 대한 $CO_2$ 대기 배출량을 계산 비교하였으며, - 화학적인 방법에 의한 $CO_2$ 대기 배출량 산정방법을 간략히 언급하였다.

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IS THE ANOMALOUS MICROWAVE EMISSION DUE TO THE ROTATION OF INTERSTELLAR PAHS? PLANCK RESULTS: PLANCK - AKARI PROJECT

  • Planck Collaboration, Planck Collaboration;Giard, M.;Berne, O.;Doi, Y.;Ishihara, D.;Joblin, Ch.;Kaneda, I.;Marshall, D.;Nakagawa, T.;Ohsawa, R.;Onaka, T.;Sakon, I.;Shibai, H.;Ysard, N.
    • 천문학논총
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    • 제27권4호
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    • pp.195-200
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    • 2012
  • We show how the rotation emission from isolated interstellar Polycyclic Aromatic Hydrocarbons (PAHs) can explain the so-called anomalous microwave emission (AME). AME has been discovered in the last decade as microwave interstellar emission (10 to 70 GHz) that is in excess compared to the classical emission processes: thermal dust, free-free and synchrotron. The PAHs are the interstellar planar nano-carbons responsible for the near infrared emission bands in the 3 to 15 micron range. Theoretical studies show that under the physical conditions of the interstellar medium (radiation and density) the PAHs adopt supra-thermal rotation velocities, and consequently they are responsible for emission in the microwave range. The first results from the PLANCK mission unexpectedly showed that the AME is not only emitted by specific galactic interstellar clouds, but it is present throughout the galactic plane, and is particularly strong in the cold molecular gas. The comparison of theory and observations shows that the measured emission is fully consistent with rotation emission from interstellar PAHs. We draw the main lines of our PLANCK-AKARI collaborative program which intends to progress on this question by direct comparison of the near infrared (AKARI) and microwave (PLANCK) emissions of the galactic plane.

주요 흙 건축재료 현황 및 건축환경 관련 물성 평가에 관한 연구 (The State of the Art and Architectural Environmental Property Evaluation of Earth Construction Material)

  • 송설영;구보경;송승영
    • 한국태양에너지학회 논문집
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    • 제26권4호
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    • pp.83-91
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    • 2006
  • As a demand for sustainable development rises, the preference for earth house (earth construction) increases gradually. However, there are few data for predicting and evaluating the thermal environment and indoor air quality of earth house. Thus, this study aims to measure thermal properties(thermal conductivity, density and specific heat) and pollutants emission intensities(formaldehyde and volatile organic compounds) of current main earth construction materials and make a comparison between earth and cement construction materials. As results, quantitative thermal properties and pollutants emission intensities of current main earth construction materials are shown.

Si(111) 기판 위에 증착된 ZnO 박막의 열처리 분위기에 따른 구조적, 광학적 특성 연구 (Effect of Ambient Gases on Thermal Annealed ZnO films deposited on Si(111) Substrates)

  • 이주영;김홍승;정은수;장낙원
    • 한국전기전자재료학회논문지
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    • 제18권8호
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    • pp.734-739
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    • 2005
  • Zinc oxide films were deposited on Si (111) substrates by radio-frequency (rf)sputtering at a room temperature and post annealed in Na, air, and $H_2O$ ambient at temperatures between $800{\circ}C$ for 2 hrs. The properties were investigated by atomic force microscope (AFM), X-ray diffraction (XRD), Auger electron spectroscopy (AES) and photoluminescence (PL). Our experiments demonstrated that ZnO films have the better crystal quality for post thermal annealing and especially in $H_2O$ ambient. Even though thermal annealing reduced deep level emission somewhat, for further getting rid off deep level emission, oxygen contents should be adjusted. In our results, $H_2O$ ambient gave the best structural and optical properties.

Regularity and coupling correlation between acoustic emission and electromagnetic radiation during rock heating process

  • Kong, Biao;Wang, Enyuan;Li, Zenghua
    • Geomechanics and Engineering
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    • 제15권5호
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    • pp.1125-1133
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    • 2018
  • Real-time characterization of the rock thermal deformation and fracture process provides guidance for detecting and evaluating thermal stability of rocks. In this paper, time -frequency characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals were studied by conducting experiments during rock continuous heating. The coupling correlation between AE and EMR during rock thermal deformation and failure was analyzed, and the microcosmic mechanism of AE and EMR was theoretically analyzed. During rock continuous heating process, rocks simultaneously produce significant AE and EMR signals. These AE and EMR signals are, however, not completely synchronized, with the AE signals showing obvious fluctuation and the EMR signals increasing gradually. The sliding friction between the cracks is the main mechanism of EMR during the rock thermal deformation and fracture, and the AE is produced while the thermal cracks expanding. Both the EMR and AE monitoring methods can be applied to evaluate the thermal stability of rock in underground mines, although the mechanisms by which these signals generated are different.

용사법에 의해 제작된 금속/세라믹 경사기능 재료의 기계적 특성 (Mechanical Properties of Metal/Ceramic FGM made by Thermal Spraying Method)

  • 김영식;남기우;김현수;오명석;김귀식
    • 동력기계공학회지
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    • 제2권3호
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    • pp.41-48
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    • 1998
  • This study was aimed at development of fabrication process of functionally graded materials(FGM), consisting of metal and ceramic by thermal spraying method. NiCrAIY/$Al_2O_3$ FGM were made by using plasma spraying onto the SS400 carbon steel substrate. And mechanical properties such as microhardness, thermal shock resistance and adhesive strength of the coating layer were investigated. Adhesive strength was evaluated by acoustic emission method. It was resulted that NiCrAIY/$Al_2O_3$ FGM made by thermal spraying method showed excellent thermal shock resistance and adhesive strength compared to the other lamellar structures of sprayed coatings and that AE is useful tool to evaluate the defect of thermal sprayed coating layer.

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Thermal catalytic de-NOX 공정에서 첨가제가 촉매의 활성에 미치는 영향에 관한 연구 (Effect of Additives on Catalytic Activity in Thermal Catalytic De-NOx Process)

  • 이진구;김태원;최재순;김정호;이재수;장경욱;박해경
    • 한국대기환경학회지
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    • 제15권3호
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    • pp.249-255
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    • 1999
  • We sdudied effect of additives on catalytic activity in thermal catalytic de-NOx process which was composed of thermal reduction, catalytic reduction and catalytic oxidation stage. Pd-Pt/${\gamma}$-$Al_2O_3$ catalysts with the addition of transition metals(Co, Cu, Fe, Ni, W, Zn, Zr) and rare earth metals(Ce, Sr) were prepared by the conventional washcoating method. Those catalysts were characterized by CO pulse chemisorption, ICP, $N_2$ adsorption, SEM and XRD. The effect of catalyst additives on NOx removal for diesel emission was studied in thermal catalytic de-NOx process at reduction temperature(350~50$0^{\circ}C$), space velocity(5,000~20,000 $hr^{-1}$) and the engine load(0~120kW). The concentraton of CO, $CO_2$, NO and $NO_2$ in the exhaust gas increased with the engine load. On the other hand the concentration of $O_2$ decreased. The de-NOx activityof all prepared catalysts increased with respect to high CO and low $O_2$ level in the thermal reduction stage of the process. Insertion of Ce to Pt-Pd/${\gamma}$-$Al_2O_3$ catalyst showed the best activity of all the catalysts under these experimental conditions. De-NOx catalysts are effective to remove CO in addition to NOx in the catalytic reduction stage.

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