Numerical Simulation of Radiation Heat Transfer of the Human Body for Determining Its Radiation Coefficient

2011 ◽  
Author(s):  
Ahmad Najjaran ◽  
Ali R. Tahavvor ◽  
Abdolkarim Najjaran ◽  
Mohammad A. Ahmadfard
Keyword(s):  
Heat Transfer ◽  
Human Body ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
The Body ◽  
Heat Radiation ◽  
Radiation Heat ◽  
Radiation Heat Flux ◽  
Radiation Coefficient ◽  
Hands And Feet

Radiation heat transfer coefficient of the human body is one of the most important factors in the field of human skin health. In this paper, the radiation coefficient of the body is calculated by considering external heat radiation of body with the infinite surrounding. At first a human body is designed, and then analysis is done on it. Two segments are assumed for human body (standing and supine). In these segments hands and feet are supposed to be totally open and stretched. In standing segment, soles and in supine segment, the entire back of the body are in contact with the ground and so don’t have heat transfer. The calculation of the results is done by weighted area average method. Radiation coefficient and radiation heat flux are calculated in various emissivity. Because of existence of air around the body in reality, the convection heat transfer is also assumed for human body. Finally two formulas are reported for these segments.

scholarly journals Experimental and Computational Investigations of Phase Change Thermal Energy Storage Canisters

2000 ◽  
Vol 122 (4) ◽  
pp. 176-182 ◽  
Author(s):  
Mounir Ibrahim ◽  
Pavel Sokolov ◽  
Thomas Kerslake ◽  
Carol Tolbert
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Melting Time ◽  
Radiation Heat ◽  
Space Experiments

Two sets of experimental data for cylindrical canisters with thermal energy storage applications were examined in this paper: 1) Ground Experiments and 2) Space Experiments. A 2-D computational model was developed for unsteady heat transfer (conduction and radiation) with phase-change. The radiation heat transfer employed a finite volume method. The following was found in this study: 1) Ground Experiments, the convection heat transfer is equally important to that of the radiation heat transfer; Radiation heat transfer in the liquid is found to be more significant than that in the void; Including the radiation heat transfer in the liquid resulted in lower temperatures (about 15 K) and increased the melting time (about 10 min.); Generally, most of the heat flow takes place in the radial direction. 2) Space Experiments, Radiation heat transfer in the void is found to be more significant than that in the liquid (exactly the opposite to the Ground Experiments); Accordingly, the location and size of the void affects the performance considerably; Including the radiation heat transfer in the void resulted in lower temperatures (about 40 K). [S0199-6231(00)00304-X]

Radiation and Convection Heat Transfer in a Porous Bed

1968 ◽  
Vol 90 (1) ◽  
pp. 51-54 ◽  
Author(s):  
W. A. Beckman
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Collection Efficiency ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Fluid Temperature ◽  
Radiation Heat ◽  
Radiation Heat Flux ◽  
Flowing Fluid ◽  
Porous Bed

The one-dimensional steady-state temperature distribution within an isotropic porous bed subjected to a collimated and/or diffuse radiation heat flux and a transparent flowing fluid has been determined by numerical methods. The porous bed was assumed to be nonscattering and to have a constant absorption coefficient. Part of the radiation absorbed by the porous bed is reradiated and the remainder is transferred to the fluid by convection. Due to the assumed finite volumetric heat transfer coefficient, the bed and fluid have different temperatures. A bed with an optical depth of six and with a normal incident collimated radiation heat flux was investigated in detail. The radiation incident on the bed at the fluid exit was assumed to originate from a black surface at the fluid exit temperature. The investigation covered the range of incident diffuse and collimated radiation heat fluxes expected in a nonconcentrating solar energy collector. The results are presented in terms of a bed collection efficiency from which the fluid temperature rise can be calculated.

scholarly journals Evaluation of radiation heat transfer in porous medial: Application for a pebble bed modular reactor cooled by CO2 gas

2013 ◽  
Vol 28 (2) ◽  
pp. 118-127
Author(s):  
Kamel Sidi-Ali ◽  
Khaled Oukil ◽  
Tinhinane Hassani ◽  
Yasmina Amri ◽  
Abdelmoumane Alem
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Free Convection ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Emergency Situation ◽  
System Of Equations ◽  
Radiation Heat ◽  
Pebble Bed ◽  
Free Convection Heat

This work analyses the contribution of radiation heat transfer in the cooling of a pebble bed modular reactor. The mathematical model, developed for a porous medium, is based on a set of equations applied to an annular geometry. Previous major works dealing with the subject have considered the forced convection mode and often did not take into account the radiation heat transfer. In this work, only free convection and radiation heat transfer are considered. This can occur during the removal of residual heat after shutdown or during an emergency situation. In order to derive the governing equations of radiation heat transfer, a steady-state in an isotropic and emissive porous medium (CO2) is considered. The obtained system of equations is written in a dimensionless form and then solved. In order to evaluate the effect of radiation heat transfer on the total heat removed, an analytical method for solving the system of equations is used. The results allow quantifying both radiation and free convection heat transfer. For the studied situation, they show that, in a pebble bed modular reactor, more than 70% of heat is removed by radiation heat transfer when CO2 is used as the coolant gas.

scholarly journals Radiation heat transfer between human and cryocabin walls

2021 ◽  
Vol 2119 (1) ◽  
pp. 012146
Author(s):  
I A Burkov ◽  
S I Khutsieva ◽  
V A Voronov
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Human Body ◽  
Transfer Problem ◽  
Radiation Heat Transfer ◽  
Vertical Wall ◽  
Heat Transfer Problem ◽  
Radiation Heat ◽  
The Impact

Abstract The paper considers the particular case of intensive radiation heat transfer in the system consisting of a human body and cryocabin walls of cryosauna. Calculations for three models have been made, namely, human-vertical wall, which is arranged parallel to a human, human-vertical wall, which is positioned at a certain angle, and a human-cryosauna. Analytical calculations are compared with Ansys-bassed numerical calculations. The impact of radiation heat transfer in this radiation-convective heat transfer problem is estimated. Conclusions are drawn about taking into account the radiation heat transfer and a rational method for calculating this heat transfer problem.

Numerical Investigation of a Symmetrical Combustion Burner and External Convection Heat Transfer Characteristics

2010 ◽  
Author(s):  
Xing Li ◽  
Li Jia ◽  
Hui Yang
Keyword(s):  
Heat Transfer ◽  
Water Flow ◽  
Heat Transfer Characteristic ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Transfer Characteristic ◽  
External Heat ◽  
Water Tank ◽  
Heat Transfer Characteristics ◽  
Radiation Heat

Combustion characteristic of natural gas (NG) in a symmetrical combustion chamber and external convection heat transfer characteristic of water flow has been investigated numerically. The burner using a combination of swirling premixed and jet diffusion flames to achieve high flame stability. The combined eddy dissipation model/finite rate chemistry (EDM/FRC) combustion models coupled with RNG k-ε turbulence model were applied to model turbulence combustion. The discrete transfer method (DTM) coupled with weighted sum of gray gas model (WSGGM) were applied to solve the radiation heat transfer. Accurate calculation results were obtained by coupling calculation of combustion in the combustion chamber and external water flow and heat transfer. The temperature fields, heat transfer characteristic in the combustor and water tank were obtained by numerical simulation. The effects of water inlet mass flow rate on combustion and external heat transfer characteristics were discussed. The results indicated that water flow has significant effect on external heat transfer. The temperature distribution is quite uniform in the water tank. Radiation heat transfer plays a dominant role of heat transfer in the combustor.

A CFD Assessment of Engine Core Zone Casing Heat Transfer

2019 ◽  
Author(s):  
Zixiang Sun ◽  
Nicholas J. Hills ◽  
Richard Scott
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Steady Flows ◽  
Radiation Heat ◽  
Core Zone ◽  
The Public ◽  
The Core

Abstract A systematic CFD investigation was conducted to assess the core zone (CZ) casing heat transfer of a large civil aircraft engine. Three key engine operating conditions, maximum takeoff (MTO), cruise (CRZ) and ground idle (GI) were analyzed. Steady flows were assumed. Turbulence was simulated using the realizable k-epsilon model in conjunction with the scalable wall function. Buoyancy effect was taken into account. Radiation was calculated using the discrete ordinate (DO) model. It was shown that the forced convection heat transfer dominates in most of the casing surface in the core zone, and radiation is of second importance in general. However, in some areas where both convection and radiation heat transfer are weak but the latter is relatively greater in magnitude than the former, radiation heat transfer could thus become dominant. In addition, the overall impact of radiation on casing heat transfer increases from MTO to CRZ and GI conditions, as the strength of engine load decreases. The overall effect of buoyancy on casing heat transfer is small, but could be noticeable in some local areas where flow velocity is low. The insight into heat transfer features on the engine core zone casing supported by quantified CFD evidences is the first in the public domain, as far as authors are aware.

Development of Numerical Simulation Method to Evaluate Heat Transfer Performance of Air Around Fuel Debris: Part 2 — Validation of JUPITER for Free Convection Heat Transfer

2017 ◽  
Author(s):  
Shinichiro Uesawa ◽  
Susumu Yamashita ◽  
Mitsuhiko Shibata ◽  
Hiroyuki Yoshida
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Calculation Result ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Air Cooling ◽  
Convection Heat ◽  
Radiation Heat ◽  
Cooling Performance ◽  
Free Convection Heat

A dry method is one of fuel debris retrieval methods for decommissioning of TEPCO’s Fukushima Daiichi nuclear power station. If stopping the water leakage from a damaged primary containment vessel (PCV) is impossible, the dry method may be adopted. Besides, the dry method may be also adopted to retrieve the fuel debris in a pedestal under a reactor pressure vessel (RPV) because accessing and retrieval of the fuel debris from the lateral sides of PCV may be adopted for retrieval of the fuel debris in the pedestal. However, the decay heat must be removed from the fuel debris without water because fuel debris is exposed to the air in the dry method. Thus, we must evaluate the air cooling performance for the fuel debris in the dry method. Japan Atomic Energy Agency (JAEA) has started the research project to develop an evaluation method by the JUPITER to understand the air cooling performance for fuel debris in the dry method. In the project, free convection heat transfer and the radiation heat transfer experiments for air are also conducted for validation of the JUPITER. In this paper, the free convection heat transfer, the radiation heat transfer, the conduction heat transfer and the Rayleigh number for the free convection in the simplified model were estimated to decide experimental conditions. We confirmed the free convection and the radiation heat transfer were important to estimate heat transfer of the debris exposed to the air in the RPV pedestal. Considering the estimations, the experiment for heat transfer and flow visualization of free convection adjacent to upward-facing horizontal surface was conducted to validate the calculation of the turbulent free convection by the JUPITER. From comparing between the calculation result and the experimental result, we confirmed that the calculation result of the JUPITER was qualitatively reasonable.

Methods for Monitoring the Temperature of GIS Bus Conductor

2014 ◽  
Vol 687-691 ◽  
pp. 770-773
Author(s):  
Gang Wu ◽  
Long Teng Li ◽  
Yun Feng Peng ◽  
Cheng Wen Zhu ◽  
Yong Liang Zhang
Keyword(s):  
Heat Transfer ◽  
Partial Discharge ◽  
Radiation Heat Transfer ◽  
Conservation Equation ◽  
Heat Radiation ◽  
Radiation Heat ◽  
Energy Conservation Equation ◽  
Heat Transfer Theory ◽  
Calculation Results ◽  
Long Time

The performance of GIS bus is directly linked with its heat radiation and temperature rise, and its long-time overheating may cause partial discharge and bus burn-up, posing a threat to the reliability of power system. This paper, based on heat transfer theory and taking into account convection and radiation heat transfer, builds the energy conservation equation and iteratively calculates the temperatures of the bus conductor and shell. The comparison of the calculation results with experimental data has confirmed the correctness of the calculation.

scholarly journals PENGARUH TIPE KACA PENUTUP 1 SISI DAN 2 SISI DENGAN ABSORBER TEMBAGA PADA SOLAR DISTILLATION TERHADAP PRODUKTIVITAS KONDENSAT AIR LAUT

JTAM ROTARY ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 13
Author(s):  
Agung Wibowo ◽  
Mastiadi Tamjidillah
Keyword(s):  
Heat Transfer ◽  
Water Productivity ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Radiation Energy ◽  
Radiation Heat ◽  
Glass Cover ◽  
Solar Distillation ◽  
Quality Of Water

Distilasi matahari merupakan suatu alat yang memanfaatkan energi radiasi matahari sebagai sumber panasnya. Penelitian ini membandingkan destilasi surya tipe penutup kaca 1 sisi dan 2 sisi dengan penyerap tembaga. Tujuan dari penelitian ini adalah untuk mengetahui perpindahan kalor yang terjadi, produktivitas air yang dihasilkan dan kualitas air yang dihasilkan. Penelitian dilakukan selama 4 hari. Hasil penelitian menunjukkan bahwa distilasi surya dengan penutup kaca 1 sisi lebih baik dibandingkan dengan penutup kaca 2 sisi. Ini terlihat dari produktivitas air yang dihasilkan. Distilasi surya dengan penutup kaca 1 sisi memiliki produktivitas air 468 ml, sedangkan destilasi surya dengan penutup kaca 2 sisi hanya 450 ml. Perpindahan panas konduksi tertinggi terjadi pada distilasi surya dengan penutup kaca 1 sisi sebesar 4064,6 Watt. Untuk konveksi perpindahan panas tertinggi terjadi pada destilasi surya dengan penutup kaca 1 sisi yaitu 0,16 Watt. Perpindahan panas radiasi tertinggi terjadi pada destilasi surya dengan penutup kaca 1 sisi sebesar 34,7 Watt. Hasil penelitian kualitas air yang dihasilkan oleh kedua distilasi surya tersebut adalah air tersebut dapat dikategorikan sebagai air bersih. Solar distillation is a device that utilizes solar radiation energy as a source of heat. This research compares solar distillation with 1 sided and 2 sided glass cover type with copper absorber. The purpose of this research is to determine the heat transfer that occurs, the productivity of the water produced and the quality of water produced. Research is doing for 4 days. The results of this research that solar distillation with 1 sided glass cover is better to 2 sided glass cover. This is seen from the productivity of the water produced. Solar distillation with 1 sided glass cover has a water productivity of 468 ml, while solar distillation with 2 sided glass cover is only 450 ml. The highest conduction heat transfer is in solar distillation with 1 sided glass cover is 4064.6 Watts. For the highest convection heat transfer is in solar distillation with 1 sided glass cover is 0.16 Watt. The highest radiation heat transfer is in solar distillation with 1 sided glass cover is 34.7 Watts. The results of research the quality of water produced by both solar distillation is that the water can be categorized as clean water.

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