• Title/Summary/Keyword: Energy loss reduction

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Thermal Behaviors of (Cu0.5Mn0.5)Fe2O4 for H2 production by thermochemical cycles (열화학싸이클 수소를 제조를 위한 (Cu0.5Mn0.5)Fe2O4의 열적 거동)

  • Kim, J.W.;Choi, S.C.;Joo, O.S.;Jung, K.D.
    • Journal of Hydrogen and New Energy
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    • v.15 no.1
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    • pp.32-38
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    • 2004
  • Thermal behaviors of $(Cu_{0.5}Mn_{0.5})Fe_2O_4$, prepared by a solid method, were investigated for $H_2$ production by a thermochemical cycle. The thermal reduction of $(Cu_{0.5}Mn_{0.5})Fe_2O_4$ started from $300^\circ{C}$ and the weight loss was 1.3 wt% up to 1200. XRD shows the prepared ferrite has the spinel structure with a lattice constant of $8.414{\AA}$ and changed to the oxygen deficient structure by thermal reduction. Oxygen and hydrogen can be separately produced by the cycles of thermal reduction and water oxidation of the oxygen deficient ferrite.

The Evaluation of the Application of Modified Wood Powder Spacers to Liner Board Mill Trials (개질처리된 목질계 스페이서의 산업용지 생산현장 적용평가)

  • Seo, Yung Bum;Yoon, Doh-Hyun;Sung, Yong Joo;Gwon, Wan-Oh;Kim, Jin-doo
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.47 no.5
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    • pp.98-103
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    • 2015
  • The reduction of the energy consumption in papermaking process become more important issue because of the regulation of green house gas (GHG) emission. Since more than half of energy for papermaking process is consumed during drying process, the increase of the drying efficiency would be very important solution for saving energy and reduction of GHG emission. The improvement of drying efficiency could be very difficult for the liner board mill because the liner board are usually made of recycled paper, OCC (old corrugated container). The short fiber and fines originated the OCC lead to compact sheet structure and delay the water flow out during wet pressing process and drying process. The application of lignocellulose spacer could provide more loose wet sheet structure and result in the higher drainage rate and the improved drying efficiency. In this study, the effects of the application of lignocellulose spacer to the liner board mill were evaluated based on the mill trial. In order to overcome the common disadvantage of the spacer, the loss of strength properties, the spacer was pretreated with amphoteric polyelectrolyte during mill trial. The results showed the application of pretreated spacer improved the drying efficiency by reducing steam consumption. And the loss in the strength properties by the spacer could be supplemented by the pretreatment.

Effect of Change of Reactor Coolant Injection Method on Risk at Loss of Coolant Accident due to Beam Tube Rupture (빔튜브파단 냉각재상실사고시 원자로냉각수 보충방법 변경이 리스크에 미치는 영향)

  • Lee, Yoon-Hwan;Lee, Byeonghee;Jang, Seung-Cheol
    • Journal of the Korean Society of Safety
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    • v.37 no.4
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    • pp.129-138
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    • 2022
  • A new method for injecting cooling water into the Korean research reactor (KRR) in the event of beam tube rupture is proposed in this paper. Moreover, the research evaluates the risk to the reactor core in terms of core damage frequency (CDF). The proposed method maintains the cooling water in the chimney at a certain level in the tank to prevent nuclear fuel damage solely by gravitational coolant feeding from the emergency water supply system (EWSS). This technique does not require sump recirculation operations described in the current procedure for resolving beam tube accidents. The reduction in the risk to the core in the event of beam tube rupture that can be achieved by the proposed change in the cooling water injection design is quantified as follows. 1) The total CDF of the KRR for the proposed design change is approximately 4.17E-06/yr, which is 8.4% lower than the CDF of the current design (4.55E-06/yr). 2) The CDF for beam tube rupture is 7.10E-08/yr, which represents an 84.1% decrease compared with that of the current design (4.49E-07/yr). In addition to this quantitative reduction in risk, the modified cooling water injection design maintains a supply of pure coolant to the EWSS tank. This means that the reactor does not require decontamination after an accident. Thermal hydraulic analysis proves that the water level in the reactor pool does not cause damage to the nuclear fuel cladding after beam tube rupture. This is because the amount of water in the chimney can be regulated by the EWSS function. The EWSS supplies emergency water to the reactor core to compensate for the evaporation of coolant in the core, thus allowing water to cover the fuel assemblies in the reactor core over a sufficient amount of time.

Loss of a Main Feedwater Pump Test Simulation Using KISPAC Computer Code

  • Jeong, Won-Sang;Sohn, Suk-Whun;Seo, Ho-Taek;Seo, Jong-Tae
    • Nuclear Engineering and Technology
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    • v.28 no.3
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    • pp.265-273
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    • 1996
  • Among those tests performed during the Yonggwang Nuclear Power Plant Units 3 and 4 (YGN 3&4) Power Ascension Test period, the Loss of a Main Feedwater Pump test at l00% power is one of the major test which characterize the capability of YGN 3&4. In this event, one of the two normally operating main feedwater pumps is tripped resulting in a 50% reduction in the feedwater flow. Unless the NSSS and Turbine/Generator control systems actuate properly, the reactor will be tripped on low SG water level or high pressurizer pressure. The test performed at Unit 3 was successful by meeting all acceptance criteria, and the plant was stabilized at a reduced power level without reactor trip. The measured test data for the major plant parameters are compared with the predictions made by the KISPAC computer code, an updated best-estimate plant performance analysis code, to verify and validate its applicability. The comparison results showed good agreement in the magnitude as well as the trends of the major plant parameters. Therefore, the KISPAC code can be utilized for the best-estimate nuclear power plant design and simulation tool after a further verification using other plant test data.

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Solar Cell Design for Large Area Multi Busbar Module Power Loss Reduction (대면적 Multi busbar 모듈 전력 손실 저감을 위한 태양전지 설계)

  • Juhwi Kim;Jaehyeong Lee
    • Current Photovoltaic Research
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    • v.11 no.1
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    • pp.34-37
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    • 2023
  • Solar energy had become the main energy industry of renewable energy along with hydroelectric power generation. One of the technologies that contributed to the popularization of photovoltaic power and the decrease in the unit price of photovoltaic modules was the large-area solar cell. However, as the area increased, the light receiving area increased and the current value increased accordingly. Since power loss occurs when the current value was large, the number of busbar was increased to increase the current collection rate, and a technology to lower the current value through half-cutting was developed. The bus bar of the solar cell served as a passage through which the generated current was transmitted. This was because when the number of busbar decreases, the moving distance of electrons increased, so the amount of power generation decreases and when it increases, shadows occured. An important aspect of the electrode design was the optimal balance of these busbars and number of fingers. Therefore, in this study, the characteristics of the solar cell according to the number of front bus bars of the large-area solar cell were simulated using Griddler 2,5 pro. After selecting the number of busbar with the best characteristics, the difference was compared by varying the number of fingers and a better direction for the number of cutting was presented.

Wear Reduction of Tappet Surface by Undulated Surface (미세요철표면을 이용한 태핏 표면의 마모 저감에 관한 연구)

  • 여창동;김대은
    • Tribology and Lubricants
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    • v.14 no.2
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    • pp.63-74
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    • 1998
  • The damage of cam/tappet surface is one of the major reasons for energy loss in an I.C. engine. High friction causes the accelerated wear of the cam/tappet surfaces which in turn changes the valve opening/closing timing. During the accelerated test evidence of both rolling fatigue and sliding abrasive wear could be found. Based on the results of the accelerated test, a scheme was devised to decrease tappet wear. Wear reduction of the tappet was achieved by using undulated surface topography in the tappet center region. The wear reduction is achieved by trapping of the wear particles in the undulations as well as by increasing the supply of lubricant to the sliding interface.

Combustion Characteristics and Activation Energy From Thermogravimetric Analysis of Bituminous and Anthracite Coal (TGA에 의한 유.무연탄의 연소특성과 활성화에너지 비교)

  • 김성철;최병선;이현동;홍성선
    • Journal of Energy Engineering
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    • v.5 no.2
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    • pp.170-175
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    • 1996
  • This study is to determined the activation energy from TGA experimental data for the bituminous and anthracite coals of three kinds which are being used in the domestic coal-fired power plants. TGA experimental data indicate that the weight loss temperature of bituminous coal is 200$^{\circ}C$ higher than that of anthracite coal. Activation energy of bituminous coal is in the range of 14∼20 Kcal/mole compared with 37∼55 Kcal/mole of anthracite coal. A reduction of particle size of coals results in the decrease of activation energy and activation energy has a good correlation with the weight loss percent of coal in the TGA experiment. Addition of CaCO$_3$ on anthracite coal caused to decrease the activation energy of 1∼23 Kcal/mole while activation energy of bituminous coal do not change significantly.

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Analysis of Performance of Building Integrated PV System into Cold Facade (건물일체형 Cold Facade PV 시스템의 성능 분석)

  • Kim, Hyun-Il;Kang, Gi-Hwan;Park, Kyung-Eun;Yu, Gwon-Jong;Suh, Seung-Jik
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1104-1105
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    • 2008
  • This paper presents the assesment of experimented data and estimated data for electrical and thermal performance evaluation of building integrated photovoltaic(BIPV) system of cold facade type. BIPV module is used to estimate the dependence of module temperature on irradiance, ambient temperature and indoor temperature. The module temperature of no free ventilated facade PV system is higher than cold facade PV system about 13.4$^{\circ}C$. By the results on simulation, the reduction of electrical power loss is 9.57% into cold facade according to free ventilation. The annual averaged PR of BIPV system into cold facade is about 73.1%.

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New Energy Recovery Concept for AC PDP Sustaining Driver Using Current Injection Method (CIM)

  • Lee, Jun-Young;Kim, Jin-Sung;So, Myeong-Seop;Cho, Bo-Hyung
    • Journal of Power Electronics
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    • v.2 no.3
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    • pp.189-198
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    • 2002
  • New concept of energy recovery for plasma display panel (PDP) Is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel Polarity together with energy Previously charged in Panel capacitance. This operation Provides zero -voltage-switching of switches and reduction of EMI by rejecting the surge current when the sustain switches are turned on. The build-up current helps to reduce transition time of panel polarity and may produce more stable light waveforms. This method shows a desirable characteristic that the circuit loss is similar to that of series resonant type energy recovery circuit which is very effective method.

Properties of lightweight matrix for inorganic insulation by cement types (시멘트 종류별 무기단열재용 경량 경화체의 특성)

  • Lim, Jeong-Jun;Pyeon, Su-Jeong;Lee, Sang-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2018.05a
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    • pp.222-223
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    • 2018
  • Recent government policies are increasing interest in zero-energy housing, a building that minimizes energy consumption (90% reduction). As the importance of building passive performance is emphasized, the role of insulation is increasing as a way to reduce indoor heat loss in order to minimize the use of cooling and heating energy. There are two main types of insulation. Organic insulation is widely used for various construction structures such as construction and industrial due to some merits such as the convenience of construction and construction cost. However, it has been pointed out as a main cause every time a fire accident occurs, Jecheon Sports Center', the fire damage of buildings caused by the use of organic insulation materials is expanding to social problems, so it is urgent to research on nonflammable inorganic insulation materials.

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