• 제목/요약/키워드: Surface heat exchange

검색결과 133건 처리시간 0.095초

대류-복사 복합 열전달을 고려한 대류 핀효율의 향상에 관한 수치적 연구 (Numerical Investigations of Enhancement of a Convective Fin Efficiency by Convection-Radiation Gonjugate Heat Transfer)

  • 이동렬;김호용;이재곤;박용국;김기대
    • Journal of Advanced Marine Engineering and Technology
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    • 제25권1호
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    • pp.146-154
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    • 2001
  • In almost all real situations, there will be a radiant interchange between adjacent fins with the base surface as well as with the external environment. In the problem of this study, a rectangular fin is attached to a based. Our concern is whether the convective fin efficiency can be increased by the radiation heat exchanged between the fin and the base surface and how much. If the fin temperature toward the tip increased by the effect of radiation, the convective heat transfer increase due to the temperature difference between the ambient temperature and the surface temperature of the fin. If this true, the efficiency of the fin due to the radiation will increase. Attention is directed toward several parameters which have major roles on getting values of the fin efficiencies in several different values of parameters. Many different cases are, therefore, to be examined to have maximum fin efficiency by varying the values of each parameter.

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Pd 촉매 담지핀을 이용한 촉매 열 교환기의 특성분석 실험 (The Catalytic heat Exchanger of Catalytic Fins Deposited With PD Catalyst)

  • 유상필;서용석;정남조;유인수;조성준
    • 한국에너지공학회:학술대회논문집
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    • 한국에너지공학회 2000년도 춘계 학술발표회 논문집
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    • pp.209-214
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    • 2000
  • The catalytic heat exchanger, which integrates two functions of heat generation and heat exchange into one equipment, was designed and its characteristics were investigated by experiments. The surface of the fin tube was deposited with Pd catalyst. The conversion of the mixture in the catalytic heat exchanger was more significantly affected by the inlet velocity of the mixture than by the inlet temperature and equivalence ratio of the mixture. It was found that the catalytic surface area of the fin tubes should be sufficiently increased to make the combustion intensity of the catalytic heat exchanger as high as possible. Results showed that the fin tubes, placed in the triangularly staggered form, should be adjusted so that the mixture flows uniformly over all the catalytic fin surfaces.

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포화상태에 놓인 C-Type 액체수소 탱크의 슬로싱이 열 유속과 BOG에 미치는 변화의 수치적 분석 (Numerical Study of Heat Flux and BOG in C-Type Liquefied Hydrogen Tank under Sloshing Excitation at the Saturated State)

  • 이진호;황세윤;이성제;이장현
    • 한국전산구조공학회논문집
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    • 제35권5호
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    • pp.299-308
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    • 2022
  • 본 논문은 슬로싱 상태에 놓인 포화 상태 액체수소탱크에서 열 유속 및 BOG(Boil-off gas)의 경향을 다루고 있다. 특히, 액체-기체간의 침투 및 혼합에 의한 열 교환에 관심을 두었다. 먼저, VOF(Volume of fluid)와 Eulerian 기반의 다상 유동모델로 모형 슬로싱 실험을 모사하여 압력을 예측하고 계측된 값과 비교하였다. 자유 수면 및 충격 압력 실험 결과와 해석 결과를 비교하였으며, 유체의 속도 예측에서 정확할 수 있음을 간접적으로 증명하였다. 그리고 2차원의 Type-C 원통형 수소탱크를 대상으로 다상열유동해석을 수행하였다. 이때 포화상태에 놓인 액체 및 기체수소를 가정하고, 해석을 통해 각 상간의 혼합에 의한 열 교환의 수준을 확인하고자 하였다. 단, 상간의 열 교환만을 관심으로 두고 있었으므로 질량전달 및 기화모델은 해석에서 제외하였다. 최종적으로 상의 혼합으로 인해 액체수소로 유입되는 열 유속의 기여도에 대하여 정리하였다. 또한 액체수소로 유입되는 열 유속과 집중 질량 기반의 간이식을 통해 BOG 발생량 및 경향을 예측하고 분석하였다.

Co/Cu/Co/FeMn 스핀밸브의 자기저항 특성 향상 연구 (Study on the Improvement of Exchange Bias and Magnetoresistance in Co/Cu/Co/FeMn Spin Valve by Heat Treatment)

  • 김홍진;배준수;노은선;이택동;이혁모
    • 한국자기학회지
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    • 제12권1호
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    • pp.24-29
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    • 2002
  • 반강자성 FeMn과 강자성 Co를 이용한 기판/Co/Cu/Co/FeMn 구조의 스핀밸브를 제조하여 자기저항 특성을 조사하였다. Cu를 하지층으로 하여 FeMn 반강자성층을 형성시킨 결과 ${\gamma}$y-FeMn과 고착층 Co와의 교환이방성 결합이 향상되었다. FeMn증착시 Ar 압력과 power를 달리해가며 최적의 FeMn 증착조건을 고찰하였다. 이로부터 FeMn과 Co간의 계면이 평탄해질수록 교환결합의 세기가 증가함을 알 수 있었다. AES 분석으로부터 열처리에 의해 Co와 Cu간 계면고용층이 소멸됨을 확인하였다. 기판/Co/Cu/Co/FeMn 스핀밸브를 열처리함으로써 교환이방성 결합과 자기저항비를 각각 3배와 1.4배 이상 향상시켰다.

요철형상의 CFD 해석을 통한 대용량 로타형 폐열회수열교환기 성능에 관한 연구 (Research on Performance of Large Rotor-type Heat Recovery Exchanger using CFD Analysis on Surface Corrugation)

  • 김동규;하병용;김근오;금종수;정석권
    • 설비공학논문집
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    • 제24권12호
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    • pp.875-880
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    • 2012
  • The field of the large volume heat exchanger for wasted heat recovery ventilation system is being expanded enormously seeing as the fact that the quantity of reducing energies are huge due to the large volume heat exchanger for wasted heat recovery system at large buildings and factories, which consume large amount of energies while it has been arising huge amount of losses in Korea because of the lack of technology. To develop large volume waste heat recovery heat exchanger, rotor type heat exchanger was simulated for the surface corrugation. Based on the simulation results produced $30,000m^3/h$ grade waste heat recovery, heat exchanger was performed for the actual experiment. In addition, performance tests exceed the capacity of a large waste heat recovery heat exchanger performance test methods proposed.

On The Variation Of The Mixed Layer Depth And The Heat Flux In The Sea Of Japan

  • Shim, Taebo;Kim, Kuh
    • 한국해양학회지
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    • 제16권2호
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    • pp.49-56
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    • 1981
  • Annual variation of the surface mixed layer depth (MLD) in the southern part of the Sea of Japan is investigated based upon the oceanographic and meteorological data taken during 1971∼1975 by the Fisheries Research and Development Agency and the Central Meteorological Office of Korea. It is found that the variation of the MLD is strongly correlated with the heat exchange between the atmosphere and sea. The MLD and heat flux vary within ranges comparable to those in the Kuroshio region found by Bathen(1972) and Wyrtki(1965)

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건축외부공간에 있어서 인체의 일사열부하(日射熱負荷) 및 열적(熱的) 쾌적성(快適性)에 관한 실험적 연구 (Human Solar Heat Load and Thermal Comfort in an Outdoor Environment)

  • 정창원;윤인
    • 한국산업융합학회 논문집
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    • 제1권2호
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    • pp.65-74
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    • 1998
  • The purpose of this paper is to investigate the mount of relief of human solar heat load and thermal comfort in outdoor environment in summer, Six different types of sites, T garden and its neighboring area in Japan, were selected as the experiment sites. The experiments were conducted from 22 to 29 August, 1994 to find the relationship between climatic conditions and human responses, Climatic conditions, subjects's thermal sensation and skin temperature were measured. Radiant heat exchange on the human body was estimated on the basis of the measured air and surface temperature and solar radiation. Thermal index Operative Temperature and New Effective Temperature was modified with the effect of the radiant heat exchange. Human thermal comfort and skin temperature is affected by the solar radiation and the sky factor in an outdoor environment. The effect of tree shade was verified on thermal comfort, The mount of relief of human solar heat load is relation to the existence of shade a solar radiation and the sky factor. The urban garden is one of the effective design element in an urban environmental planning.

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영동대설 사례와 관련된 동해상의 현열속과 잠열속 분포 특성 (Characteristics of Sensible Heat and Latent Heat Fluxes over the East Sea Related with Yeongdong Heavy Snowfall Events)

  • 김지언;권태영;이방용
    • Ocean and Polar Research
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    • 제27권3호
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    • pp.237-250
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    • 2005
  • To investigate the air mass modification related with Yeongdong Heavy snowfall events, we examined sensible and latent heat fluxes on the East Sea, the energy exchange between atmosphere and ocean in this study. Sensible and latent heats were calculated by a bulk aerodynamic method, in which NCEP/NCAR reanalysis data and NOAA/AVHRR weekly SST data with high resolution were used. Among winter precipitation events in the Yeongdong region, 19 heavy precipitation events $(1995{\sim}2001)$ were selected and classified into three types (mountain, cold-coastal, and warm types). Mountain-type precipitation shows highly positive anomalies of sensible and latent heats over the southwestern part of the East Set When separating them into the two components due to variability of wind and temperature/ specific Humidity, it is shown that the wind components are dominant. Cold-coastal-type precipitation also shows strong positive anomalies of sensible and latent heats over the northern part and over the central-northern part of the East Sea, respectively. It is shown that the sensible heat anomalies are caused mostly by the decrease of surface air temperature. So it can be explained that cold-coastal-type precipitation is closely related with the air mass modification due to cold air advection over warm ocean surface. But in warm-type precipitation, negative anomalies are found in the sensible and latent heat distributions. From this result, it may be postulated that warm-type precipitation is affected by the internal process of the atmosphere rather than the atmosphere-ocean interaction.

산화알루미늄의 치환에 따른 붕규산 유리의 분상 미 이온교환성에 관한 연구 (Ion Exchange Capacity and Phase Separation of Alkali Borosilicate Glass by Substituting $Al_2O_3$)

  • 김병호;유영문
    • 한국세라믹학회지
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    • 제21권1호
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    • pp.41-50
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    • 1984
  • The ion-exchange porous glasses were prepared by heat treating and subsequently acid treating the (95-y) $SiO_2$.$yB_2O_3$.$5Na_2O+xAl_2O_3$ glasses with y=55, 45, 35, 25. mole% and x=0, 2, 5, 9 mole% It was then investigated how the cation exchange capacity was affected by the phase separation in these glasses. For that matter such quantities as alkali extraction amount pore volume and specific surface area of the glasses were measured. The phase separation in these glasses was in general suppressed by the addition of $Al_2O_3$ maximally around the composition of 5 mole% $Al_2O_3$ This may be because the micro-phase separation prevailed in the glass of that composition over the macro-phase separation increasing thereby the specific surface area as well as the residual amount Al of after acid-treatment and accordingly the cation exchange capacity. The maximum values of the cation exchange capacity was observed to be about 150meq/100g for the glasses of (40-50) $SiO_2$ (55~45)$yB_2O_3$. $5Na_2O+5Al_2O_3$.

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핀이 부착된 MF증발관의 열전달 특성에 대한 해석적 연구 (An Analytical Study on the Heat Transfer Characteristics of MF Evaporation Tubes Attached with a Fin)

  • 박용석;성홍석;서정세
    • 한국기계가공학회지
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    • 제20권1호
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    • pp.48-56
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    • 2021
  • In this study, the heat transfer process around the finned channel tubes is numerically examined. Serially arranged tubes of an evaporator were used for heat exchange. The numerical analysis results confirmed that the vortex generated at the rear of the channel pipe was caused by the fin. Furthermore, it was also confirmed that the temperature difference was large between the inlet and outlet ends of the fin. The temperature of the location where the fin was attached to the channel pipe was found to be close to the surface temperature of the channel wall. However, the temperature rose rapidly closer to the ambient air temperature of 350 K towards the fin end, located at a distance of 0.035 m; it was found to have a significant influence on the heat transfer around the fin-attached channel tube. The wider the vertical flow path, the lower the total heat transfer coefficient. However, the overall heat transfer coefficient increased as the horizontal flow path narrowed. The increment is attributed to an increase in the heat transfer amount due to increased heat transfer surface.