• 제목/요약/키워드: Thermal Efficiency

검색결과 3,002건 처리시간 0.027초

후면전극형 태양전지의 열해석에 관한 연구 (Thermal Analysis for High Efficiency of Point Contact Solar Cell)

  • 남태진;강이구
    • 한국전기전자재료학회논문지
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    • 제24권5호
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    • pp.351-354
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    • 2011
  • This paper was carried about thermal analysis for high efficiency point contact solar cell. Therefore, we carried about 2-D device and process simulator according to design and process parameters. As a result of simulations, power transfer efficiency have decreased more increasing temperature. Especially, power transfer efficiency of room temperature have been showed 25%. The other hand, power transfer efficiency of 350 K kalvin temperature have been showed 20%. Therefore, we will considered design with thermal dissipation of device.

저온열원의 특성에 따른 ORC 성능해석 최적화 연구 (Optimization Study on the Performance Analysis of Organic Rankine Cycle for Characteristics of Low Temperature Heat Sources)

  • 엄홍선;윤천석;김영민;신동길;김창기
    • 설비공학논문집
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    • 제24권1호
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    • pp.51-60
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    • 2012
  • Optimization procedures of performance analysis for ORC(Organic Rankine Cycle) system are established to the characteristics of low temperature heat sources such as open-type and closed-type. Effective heat recovery and heat extraction related to maximum power of the cycle as well as heat quality and thermal efficiency must be considered in the case of the open-type low temperature heat source. On the other hand, in the case of the closed-type low temperature heat source, only thermal efficiency is important due to constant heat input. In this study, thermal efficiency and exergy efficiency representing a level of close to Carnot cycle are studied, as useful index for the optimization of the ORC system. To validate the results of cycle analysis, those are compared with appropriate experimental data of ORC system as a thermal efficiency point of view.

지중 열교환기용 시멘트 그라우트에 관한 연구 (A study on cement-based grout for ground heat exchangers)

  • 이동주;백환조;김경만
    • 산업기술연구
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    • 제31권B호
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    • pp.27-36
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    • 2011
  • In this paper, the applicability of cement grout has been studied as an alternative to bentonite grout for backfill ground heat exchangers. To provide an optimal mixture design, the thermal conductivity of cement grout and bentonite grout with various mixture ratios were experimentally evaluated and compared. Numerical analyses using Fluent(FVM program) were applied to compare the thermal transfer efficiency of the cement grout with that of the bentonite grout used in the construction. Also the effective ground thermal conductivity was measured by In-situ thermal response test. The results showed that the thermal efficiency of the cement grout was better than the bentonite grout. Consequently, the cement grout could be an alternative with more thermal efficiency to bentonite grout for ground heat exchangers.

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온돌의 열효율에 관한 실험적 연구 (An Experimental Study on the Thermal Efficiency of the Ondol House Beating System)

  • 배순훈;강신형
    • 대한설비공학회지:설비저널
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    • 제4권3호
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    • pp.183-190
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    • 1975
  • Most Korean houses are heated by the Ondol heating system. There has been, however, no reasonable design procedure availabe yet for the system. The conventional design should be improved to have auniform floor surface. temperature distribution and to have a high thermal efficiency. Thermal efficiencies of the ondol were defined and the method of experimentation was studied. An experiment, using a life-size model which was well insulated, was performed to observe the variation in thermal efficiency as the length of fuel burning time was varied.

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suspension preheater thermal efficiency 에 대한 종합

  • 한국양회공업협회
    • 시멘트
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    • 통권48호
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    • pp.20-28
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    • 1972
  • 본 논문은 Frankenberger씨의 논문을 번역한 것이다. preheater의 열적 성능 평가를 위해선 calcining degree, thermal efficiency 및 calorific efficiency를 이용하고 있으며 1kg의 dust circulation으로 30kcal/kg$\cdot$cli의 연료 소모량을 증가시키고 있어 4단 이상으로 증가시키는 문제도 대두 연구하고 있다.

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태양 열 전기 복합생산 PVT Water and PVT Air 모듈의 실험적 성능비교 연구 (An Experimental Comparison Study of PVT Water and PVT Air Modules for Heat and Power Co-Generation)

  • 이광섭;앤드류;강은철;이의준
    • 설비공학논문집
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    • 제26권12호
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    • pp.559-564
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    • 2014
  • The development of photovoltaic-thermal (PVT) technology has been introduced in recent years specifically to increase PV efficiency. One of the characteristics of PV systems is that the electricity generation increases as the solar radiation increases whereas the efficiency decreases because of high surface temperatures. Using a photovoltaic-thermal system, the surface temperature can be decreased by capturing the excess heat and the efficiency can be increased due to these characteristics. In this paper, three cases are introduced : 1) PV_r as the reference case, 2) PVT_a, which uses air as a heat source, and 3) PVT_w, which uses water as a heat source. Experiments were performed, analyzed, and compared to examine the effect of the PVT type on the efficiency of the system. The results showed that ETC($%/^{\circ}C$) efficiency of the PVT cases was increased versus the reference case due to decreasing surface temperature. Total efficiencies, which are electrical efficiency and thermal efficiency, for each PVT are tested and found to be 12.22% for PV_r, 29.50% for PVT_a, and 68.74% for PVT_w.

가열탱크 내부 스크류 회전속도에 따른 전기보일러의 열성능에 관한 연구 (Study on Thermal Performance of the Electric Boiler according to Screw Rotation Speed in Heating Tank)

  • 금종수;김동규;박종일
    • 한국지열·수열에너지학회논문집
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    • 제11권3호
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    • pp.13-19
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    • 2015
  • This study was aimed at the heating tank with a screw-rotation device for improving the thermal efficiency of electric boiler. In the proposed system, analysis items were the heater rod surface temperature variation, reaching time for set temperature and thermal efficiency. The following conclusions are obtained from this experimental study. (1) When screw speed increases, the time reaching for set temperature tended to be shorter. (2) When the rotation speed becomes 300 rpm, the surface temperature difference between the right and left heater rod decreases by 49%, from $19.7^{\circ}C$ to $9.7^{\circ}C$ in average. (3) When the rotation speed is over 250 rpm, proposed heating tank structure appeared to be effective in terms of thermal efficiency. Thermal efficiency with the rotation speed 300 rpm is improved by 3.8% compared to the case of rotation speed 0 rpm.

반사판을 이용한 고정식 집속형 태양광.열복합패널의 성능평가 (Performance Evaluation of Fixed-concentrated Photovoltaic/Thermal Hybrid Panel using Reflector)

  • 서유진;허창수
    • 한국태양에너지학회 논문집
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    • 제25권4호
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    • pp.85-92
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    • 2005
  • One of the most effective methods for utilizing solar energy is to combine thermal solar and optical energy simultaneously using a hybrid panel. Many systems using various kinds of photovoltaic panels have already been constructed. But utilizing solar energy by means of a hybrid panel with concentrator has not been to be attempted yet. Normally if sunlight is directed on the solar cell, and there is no increase in temperature, the absorption energy of each cell will increase per unit area. In a silicon solar cell. however, cell conversion efficiency decreases according to the increasing temperature. Therefore, to maintain cell conversion efficiency under normal condition, it is necessary to keep the cell at operating temperature. we design and make new hybrid panel with cooling system to prevent increasing of temperature on cell, collect effectively thermal energy. We compared performance of new hybrid panel with PV module and thermal panel. We also evaluated conversion efficiency, electric power and thermal capacity and confirmed cooling effect from thermal absorption efficiency.

터빈 추기를 이용한 재생 유기랭킨사이클의 열역학적 성능 해석 (Thermodynamic Performance Analysis of Regenerative Organic Rankine Cycle using Turbine Bleeding)

  • 김경훈;황선;김만회
    • 한국수소및신에너지학회논문집
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    • 제26권4호
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    • pp.377-385
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    • 2015
  • This paper presents a thermodynamic performance analysis of regenerative organic Rankine cycle (ORC) using turbine bleeding to utilize low-grade finite thermal energy. Refrigerant R245fa was selected as the working fluid. Special attention is paid to the effects of the turbine bleeding pressure and the turbine bleed fraction on the thermodynamic performance of the system such as net power production and thermal efficiency. Results show that the thermal efficiency has an optimum value with respect to the turbine bleeding pressure and the net power production is lower than the basic ORC while the thermal efficiency is higher.

스크류 캡슐형 밀폐식 빙축열시스템의 성능시험에 관한 연구 (Study on the Performance Testing of the Closed Ice Thermal Energy Storage System using Screw Capsules)

  • 김경환
    • 한국태양에너지학회 논문집
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    • 제26권4호
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    • pp.39-45
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    • 2006
  • The decrease in the summer peak electric load in our country is very important. The government has arranged and implemented a lot of support policies and statutes to decrease the peak electric load. And the ice thermal energy storage system is known as one of the alternatives. The purpose of this paper is to evaluate the efficiency and thermal characteristics of the closed ice thermal energy storage system using screw capsules. The measured thermal energy storage density is about 18.4 USRT-h/m3 (=232.9 MJ/m3), which is higher than 13.0 USRT-h/m3 (=164.6 MJ/m3), a low criterion of normal performance. And The efficiency of the discharging process and the total energy utilization is 96.2% and 2028.4 kcal/kWh respectively.