• 한국환경복원기술학회지
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• 제20권5호
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• pp.67-81
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• 2017

Because of lack of accurate understanding of the mechanism of urban heat island (UHI) phenomenon and lack of scientific discussion, it is hard to come up with effective measures to mitigate UHI phenomenon. This study systematically described the UHI and suggested the solutions using green-infrastructure (green-infra). The factors that control UHI are very diverse: radiant heat flux, latent heat flux, storage heat flux, and artificial heat flux, and the air temperature is formed by the combination effect of radiation, conduction and convection. Green-infra strategies can improve thermal environment by reducing radiant heat flux (the albedo effect, the shade effect), increasing latent heat flux (the evapotranspiration effect), and creating a wind path (cooling air flow). As a result of measurement, green-infra could reduce radiant heat flux as $270W/m^2$ due to shadow effect and produce $170W/m^2$ latent heat flux due to evaporation. Finally, green-infra can be applied differently on the macro(urban) scale and micro scale, therefore, we should plan and design green-infra after the target objects of structures are set.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.3-6
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• 2012

Analysis method for the radiation heat transfer from the duct burner flame to the heat exchanger in a Heat Recovery Steam Generator (HRSG) was presented to supplement the existing thermal design process. Flame on a burner and a heat exchanger were postulated as imaginary planes and flame temperature, surface and emissivity was simplified in a aspect of engineering approach. The calculated local flame radiative heat flux on the heating surface was compared with the heat flux of 3-atomic gas radiation and convection.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.13-18
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• 2006

Radiant burners are applicable to drying, preheating and curing in materials manufacturing processes. High radiation efficiency is one of the most important performance criteria for these burners. The wide variation in reported radiation efficiencies are partly due to the differences in the measurement techniques. In the present work, water cooled radiant heat flux meter was used to measure radiant heat flux from a metal fiber mat burner. Non-contact type thermometer was also utilized to measure the surface temperature of the burner. Combustion gas was measured by gas analyzers. According to the thermal loads and stoichiometric ratios, radiant heat transfer ratio and combustion performance were discussed here in.

• 한국연소학회지
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• 제11권1호
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• pp.27-33
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• 2006

Radiant burners are applicable to drying, preheating and curing in materials manufacturing processes. Radiation efficiency is one of the important performance criteria for these burners. The wide variation in reported radiation efficiencies are partly due to the differences in the measurement techniques. In the present work, water cooled radiant heat flux meter was used to measure radiant heat flux from a metal fiber mat burner. Non-contact type thermometer was also utilized to measure the surface temperature of the burner. Combustion gas was measured by gas analyzers. According to the thermal loads and stoichiometric ratios, radiant heat transfer ratio and combustion performance were discussed here in.

• 한국화재소방학회논문지
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• 제21권3호
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• pp.78-83
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• 2007

석유류 중에서도 차량, 선박, 보일러 등에 많이 사용되고 있는 디젤유는 휘발유나 등유보다도 연소시에 발열량이 높기 때문에, 화재 발생시에 큰 피해를 초래한다. 따라서 본 연구는 시중에 판매중인 디젤유을 이용하여 액면화재 실험을 하였으며, 연소시에 화염의 내부온도와 화염으로부터 발생되는 복사열에 대해서 측정하였다. 디젤유의 순간 최대화염온도는 $900^{\circ}C$ 이상되는 것으로 나타났으며, 평균 최대화염온도는 $800^{\circ}C$ 이상으로 나타났다. 또한 최대화염온도는 가연성 액체의 표면으로부터 5 H/D에서 나타났으며, 이 거리 보다 멀어질 수로 화염의 온도는 낮아졌다. 복사열의 경우 저장용기의 크기와 시료의 량에 따라서 크게 달라지는 것을 알 수 있었으며, 실험 용기의 크기가 0.5 m이고, 시료량이 13 mm와 20 mm에서는 각각 92.29 kW와 117.43 kW로 나타났으며, 크기가 1.0 m의 용기에서는 각각 364.35 kW와 405.88 kW로 나타났다.

• 대한기계학회논문집B
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• 제30권10호
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• pp.950-956
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• 2006

A mathematical heat transfer model for the prediction of heat flux on the slab surface and temperature distribution in the slab has been developed by considering the thermal radiation in the furnace and transient conduction governing equations in the slab, respectively. The furnace is modeled as radiating medium with spatially varying temperature and constant absorption coefficient. The slab is moved with constant speed through non-firing, charging, preheating, heating, and soaking zones in the furnace. Radiative heat flux which is calculated from the radiative heat exchange within the furnace modeled using the FVM by considering the effect of furnace wall, slab, and combustion gases is applied as the boundary condition of the transient conduction equation of the slab. Heat transfer characteristics and temperature behavior of the slab is investigated by changing such parameters as absorption coefficient and emissivity of the slab. Comparison with the experimental work shows that the present heat transfer model works well for the prediction of thermal behavior of the slab in the reheating furnace.

• 한국지구과학회지
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• 제39권1호
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• pp.1-22
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• 2018

Eight different data sets are examined in order to gain insight into the surface heat flux traits of the East Asian marginal seas. In the case of solar radiation of the East Sea (Japan Sea), Coordinated Ocean-ice Reference Experiments ver. 2 (CORE2) and the Objectively Analyzed Air-Sea Fluxes (OAFlux) are similar to the observed data at meteorological stations. A combination is sought by averaging these as well as the Climate Forecast System Reanalysis (CFSR) and the National Centers for Environmental Prediction (NCEP)-1 data to acquire more accurate surface heat flux for the East Asian marginal seas. According to the Combination Data, the annual averages of net heat flux of the East Sea, Yellow Sea, and East China Sea are -61.84, -22.42, and $-97.54Wm^{-2}$, respectively. The Kuroshio area to the south of Japan and the southern East Sea were found to have the largest upward annual mean net heat flux during winter, at -460- -300 and at $-370--300Wm^{-2}$, respectively. The long-term fluctuation (1984-2004) of the net heat flux shows a trend of increasing transport of heat from the ocean into the atmosphere throughout the study area.

• 대한기계학회논문집
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• 제14권2호
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• pp.453-462
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• 1990

The interaction of forced convection-conduction with thermal radiation in laminar boundary layer over a plate fin is studied numerically. The analysis is based on complete solution whereby the heat conduction equation for the fin is solved simultaneously with the conservation equations for mass, momentum and energy in the fluid boundary layer adjacent to the fin. The fluid is a gray medium and diffusion(Rosseland) approximation is used to describe the radiative heat flux in the energy equation. The resulting boundary value problem are convection-conduction parameter N$_{c}$ and radiation-conduction parameter m, Prandtl number Pr. Numerical results are presented for gases with the Prandtl numbers of 0.7 & 5 with values of N$_{c}$ and M ranging from 0 to 10 respectively. The object of this study is to provide the first results on forced convection-radiation interaction in boundary layer flow over a semi-infinite flay plate which can be used for comparisons with future studies that will consider a more accurate expression for the radiative heat flux. The agreement of the results from the complete solution presented by E. M. Sparrow and those from this paper for the special case of M=0 is good. The overall rate of heat transfer from the fin considering radiative effect is higher than that from the fin neglecting radiative effect. The local heat transfer coefficient with radiative effect is higher than that without radiative effect. In the direction from tip to base, those coefficients decrease at first, attain minimum, and then increase. The larger values of N$_{c}$ M, Pr give rise to larger fin temperature variations and the fin temperature without radiative effect is always higher than that with radiative effect.

• 한국안전학회지
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• 제32권2호
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• pp.14-20
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• 2017

A numerical study was conducted to identify the predictive performance for the bare-bead thermocouple (TC) using FDS (Fire Dynamics Simulator) in simulated thermal environments of fire. A relative prediction bias of TC temperature calculated from reverse-radiation correction by FDS was evaluated with the comparison of previous experimental data. As a result, it was identified that the TC temperatures predicted by FDS were lower than the temperatures measured by bare-bead TC for the ranges of heat flux and gas temperature considered. The relative prediction bias of TC temperature by FDS was gradually increased with the increase in radiative heat flux and also significantly increased with the decrease in the gas temperature. Quantitatively, at the gas temperature of $20^{\circ}C$, the TC temperature predicted by FDS had the relative bias of approximately -20% with the radiative heat flux of $20kW/m^2$ corresponding to thermal radiation level of the flashover. It is predicted from the present study that more accurate validation of fire modeling will be possible with the quantitative prediction bias occurred in the process of reverse-radiation correction of temperature predicted by FDS.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권3호
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• pp.117-128
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• 2002

This paper describes the smoke filling process of a fire field model based on a self-deve-loped SMEP (Smoke Movement Estimating Program) code to the simulation of fire induced flows in the two types of atrium space containing a ceiling heat flux. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k-$\varepsilon$ turbulence model with buoyancy production term. Also it solves the radiation equation using the discrete ordinates method. Compressibility is assumed and the perfect gas law is used. Comparison of the calculated upper-layer average tempera-ture and smoke layer clear height with the zone models has shown reasonable agreement. The zone models used are the CFAST and the NBTC one-room. For atrium fires with ceiling glass the ceiling heat flux by solar heat causes a high smoke temperature near the ceiling. However, it has no effect on the smoke movement such as the smoke layer clear heights that are important in fire safety. In conclusion, the smoke layer clear heights that are important in evacuation activity except the early of a fire were not as sensitive as the smoke layer tem-perature to the nature of ceiling heat flux condition. Thus, a fire sensor in atrium with ceiling glass has to consider these phenomena.