• Title, Summary, Keyword: radiation heat flux

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Experimental Study of Radiation Heat Flux for the Pool and Spill Fire in Petroleum Storage Tanks (석유류 저장 탱크에서의 액면 및 유츌화재에 대한 복사열의 실험적 연구)

  • Kim, Hong;Park, Hyung-Ju
    • Journal of the Korean Society of Safety
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    • v.19 no.1
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    • pp.88-93
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    • 2004
  • This experimental study was carried out to evaluate effect of the radiation heat flux for the pool and spill fire in petroleum storage tanks, which were made form steel. Each of them had the capacity of 250, 2500 and 25000 liter, respectively. The effects of the radiation heat flux are as follows; 1) The intensity of radiation heat flux from a flame decreased exponentially with increasing distance from outside wall of tanks, and increased significantly with surface area of tank and dyke. 2) In the case of 25000L tank, the radiation heat flux was about max. 98.9kW/$m^2$ in 1m from wall of tank. 3) The distance, that was able to ignite wood or plastics by radiation heat flux of approximately 12.5kW/$m^2$, was about 3.14m from wall of 25000L tank.

Performance Comparison of an Urban Canopy Model under Different Meteorological Conditions (기상 조건에 따른 도시 캐노피 모형의 성능 비교)

  • Ryu, Young-Hee;Baik, Jong-Jin;Lee, Sang-Hyun
    • Atmosphere
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    • v.22 no.4
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    • pp.429-436
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    • 2012
  • The performances of the Seoul National University Urban Canopy Model (SNUUCM) under different meteorological conditions (clear, cloudy, and rainy conditions) in summertime are compared using observation dataset obtained at an urban site. The daily-averaged net radiation, sensible heat flux, and storage heat flux are largest in clear days and smallest in rainy days, but the daily-averaged latent heat flux is similar among clear, cloudy, and rainy days. That is, the ratio of latent heat flux to net radiation increases in order of clear, cloudy, and rainy conditions. In general, the performance of the SNUUCM is better in clear days than in cloudy or rainy days. However, the performance in simulating sensible heat flux in clear days is as poor as that in rainy days. For all the meteorological conditions, the performance in simulating latent heat flux is worst among the performances in simulating net radiation, sensible heat flux, and latent heat flux. The normalized mean error for latent heat flux is largest in rainy days in which the relative importance of latent heat flux in the surface energy balance becomes greatest among the three conditions. This study suggests that improvements to the parameterization of processes that are related to latent heat flux are particularly needed.

Analysis of Variations in Soil Heat Flux and Air Temperature by Net Radiation at a Mud Flat in Hampyeong Bay (함평만 갯벌에서 순복사에 의한 토양열 플럭스와 기온의 변동 분석)

  • Park, Ho-seon;Kwon, Byung Hyuk;Kim, Il-Kyu;So, Yoon Hwan;Oh, Se Bong;Kang, Dong-hwan
    • Journal of Environmental Science International
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    • v.26 no.9
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    • pp.1101-1110
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    • 2017
  • In this study, we analyze changes in soil heat flux and air temperature in August (summer) and January (winter) according to net radiation, at a mud flat in Hampyeong Bay. Net radiation was observed as $-84.2{\sim}696.2W/m^2$ in August and $-79.4{\sim}352.5W/m^2$ in January. Soil heat flux was observed as $-80.7{\sim}139.5Wm^{-2}$ in August and $-49.09{\sim}137W/m^2$ in January. Air temperature was observed as $24.2{\sim}32.9^{\circ}C$ in August and $-1.5{\sim}11.1^{\circ}C$ in January. The rate of soil heat flux for net radiation ($H_G/R_N$) was 0.17 in August and 0.34 in January. Because the seasonal fluctuation in net radiation was bigger than the soil heat flux, net radiation in August was bigger than in January. We estimated a linear regression function to analyze variations in soil heat flux and air temperature by net radiation. The linear regression function and coefficient of determination for the soil heat flux by net radiation was y=0.19x-7.94, 0.51 in August, and y=0.39x-11.69, 0.81 in January. The time lag of the soil heat flux by net radiation was estimated to be within ten minutes in August 2012 and January 2013. The time lag of air temperature by net radiation was estimated at 160 minutes in August, and 190 minutes in January.

Heat Fluxes in the Marine Atmospheric Surface Layer around the Korean Peninsula based on Satellite Data (위성자료를 이용한 한반도 주변 해상 대기표층의 열속)

  • HONG, Gi-Man;KWON, Byung-Hyuk;KIM, Young-Seup
    • Journal of Fisheries and Marine Sciences Education
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    • v.17 no.2
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    • pp.209-217
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    • 2005
  • The energy balance of the surface layer of the water (the Yellow Sea, the East China Sea and the East Sea) was examined using satellite data. Variations of the net heat flux were similar to those of the latent heat flux which was more intensive than the sensible heat flux. The sensible heat flux was affected the difference between the sea surface temperature and the air temperature and was less important over the Yellow Sea. The maximum of the latent heat flux occurred in autumn when the air is drier and the wind is stronger. The shortwave radiation flux decreased with the latitude and depended on the cloudiness as the longwave radiation flux does. Annual variations of heat fluxes show that the latent heat flux was more intensive over the East China Sea than the East Sea and the Yellow Sea, while the spatial differences of the other heat fluxes were weak.

Introduction of Japanese Ocean Flux data sets with Use of Remote sensing Observations (J-OFURO)

  • Kubota, Masahisa
    • Proceedings of the KSRS Conference
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    • pp.231-236
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    • 1999
  • Accurate ocean surface fluxes with high resolution are critical for understanding a mechanism of global climate. However, it is difficult to derive those fluxes by using ocean observation data because the number of ocean observation data is extremely small and the distribution is inhomogeneous. On the other hand. satellite data are characterized by the high density, the high resolution and the homogeneity. Therefore, it can be considered that we obtain accurate ocean surface by using satellite data. Recently we constructed ocean surface data sets mainly using satellite data. The data set is named by Japanese Ocean Flux data sets with Use of Remote sensing Observations (J-OFURO). Here, we introduce J-OFURO. The data set includes shortwave radiation, longwave radiation, latent heat flux, sensible heat flux, and momentum flux etc. Moreover, sea surface dynamic topography data are included in the data set. Radiation data sets covers western Pacific and eastern Indian Ocean because we use a Japanese geostationally satellite (GMS) to estimate radiation fluxes. On the other hand, turbulent heat fluxes are globally estimated. The constructed data sets are used and shows the effectiveness for many scientific studies.

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A Calculation Method on Heat Flux from Ondol Floor Surface (온돌면(溫突面)의 방열량(放熱量) 산정방법(算定方法)에 관한 연구(硏究))

  • Sohn, Jang Yeul;Ahn, Byung Wook;Pang, Seung Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.1 no.2
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    • pp.173-181
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    • 1989
  • Until recently there was a lack of reliable performance data for the design and operation of Ondol heating systems. This paper presents a calculation method on heat flux from Ondol floor surface. Total heat flux from floor consists of radiation and convection component. In order to analyse the characteristics of both radiation and convection heat flux, each surface temperature is measured and several temperatures near each wall are measured vertically and horizontally in a practical Ondol heating space. Radiation heat flux is calculated and analysed by Gebhart's Absorption Factor Method with the consideration of instantaneous radiant exchanges. Convection heat output is derived from the vertical temperature profiles near floor. The vertical temperature profiles could be expressed by nonlinear regression equation models and convection coefficients could be estimated by the equations. As a result, radiation, convection and total heat flux are suggested by the expression of difference between floor surface and room air temperature.

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Estimating the urban radiation heat flux distribution and the reduction effect of building and tree shade (건물과 수목의 그림자에 의한 도시의 열 분포 산정 및 저감효과 연구)

  • Park, Chae-Yeon;Lee, Dong-Kun;Yoon, June-Ha
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.21 no.6
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    • pp.1-13
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    • 2018
  • Mapping radiation heat flux of urban area is essential for urban design and landscape planning. Because controlling urban geometry and generating green space are important urban design strategies for reducing urban heat, urban planner and designer need to recognize the micro urban heat distribution for adequate urban planning. This study suggests a new methodology for mapping urban radiation heat flux in a micro scale considering buildings and trees' shade. For doing that, firstly, we calculate net radiation for each urban surfaces (building, road (not shaded, building shaded, tree shaded), ground (not shaded, building shaded, tree shaded), tree (not shaded, building shaded)). Then, by multiplying the area ratio of surfaces to the net radiation, we can obtain the radiation heat flux in micro-scale. The estimated net radiation results were found to be robust with a $R^2$ of 90%, which indicates a strong explanatory power of the model. The radiation heat flux map for 12h $17^{th}$ August explains that areas under the building and tree have lower net radiation heat flux, indicating that shading is a good strategy for reducing incident radiation. This method can be used for developing thermal friendly urban plan.

Surface Heat Budget of the Northern Sea of Cheju Island for June-August 1993 and 1994 (제주도 북부해역의 표면 열수지 해석 -1993년과 1994년 하계의 경우-)

  • 김해동;양성기
    • Journal of Environmental Science International
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    • v.4 no.3
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    • pp.197-206
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    • 1995
  • Surface heat balance of the northern sea of Cheju Island for summer in 1993 and 1994 is analyzed using the observation data obtained by Marine Research Institute, Cheju National University. Each flux elements at the sea surface is derived from the marine meteorological reports with application of an aerodynamical bulk method for the turbulent heat fluxes, and empirical formulae for the long-wave radiation heat fluxes. The flux divergence of oceanic heat transport and the rate of heat storage in the ocean are estimated as residual. The features of the surface heat balance are mainly decided by the solar radiation flux and the latent heat flux for 199B. But the Bowen Ratios were large for 1993. This means that the sensible heat fluxes were nearly equal to the latent heat fluxes for 1993. In this period, mean flux divergence of oceanic heat transport is about 130 W/$m^2$.

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Estimation Method of Evapotranspiration over Goheung bay Wetland (고흥만 습지에서 증발산량의 산출 방법)

  • KWON, Byung Hyuk;KIM, Dong Su;KIM, Geun Hoi;KANG, Dong Hwan
    • Journal of Wetlands Research
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    • v.10 no.1
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    • pp.21-30
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    • 2008
  • Evapotranspiration is an important factor in the energy interaction process between the surface and the air. Over a vegetable canopy, evapotranspiration was investigated by measuring the sensible heat flux, the soil heat flux and the net radiation flux. Evapotranspiration based on routine AWS data is in good agreement with that estimated from the energy balance equation except for weak wind shear less than $1s^{-1}$ and a cloudy period. Soil heat flux can be approximately to 10% of net radiation flux at the lower layer. When the slope of the saturation vapor pressure versus temperature curve ($de_s/dT$) is approximated to 1.5, the evapotranspiration can be described in function of the net radiation energy flux over Goheung bay wetland covered with the vegetable canopy, reeds.

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