scholarly journals DETERMINING NATURAL CONVECTION HEAT TRANSFER COEFFICIENT OF HUMAN BODY

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Ahmad Najjaran Kheirabadi ◽  
Abdolkarim Najjaran Kheirabadi ◽  
Ali Fotoohabadi ◽  
Alireza Shiri Shorije
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Transfer Coefficient ◽  
Human Body ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

scholarly journals Experimental and Theoretical Investigation of the Natural Convection Heat Transfer Coefficient in Phase Change Material (PCM) Based Fin-and-Tube Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 716
Author(s):  
Saulius Pakalka ◽  
Kęstutis Valančius ◽  
Giedrė Streckienė
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Energy Storage ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

Latent heat thermal energy storage systems allow storing large amounts of energy in relatively small volumes. Phase change materials (PCMs) are used as a latent heat storage medium. However, low thermal conductivity of most PCMs results in long melting (charging) and solidification (discharging) processes. This study focuses on the PCM melting process in a fin-and-tube type copper heat exchanger. The aim of this study is to define analytically natural convection heat transfer coefficient and compare the results with experimental data. The study shows how the local heat transfer coefficient changes in different areas of the heat exchanger and how it is affected by the choice of characteristic length and boundary conditions. It has been determined that applying the calculation method of the natural convection occurring in the channel leads to results that are closer to the experiment. Using this method, the average values of the heat transfer coefficient (have) during the entire charging process was obtained 68 W/m2K, compared to the experimental result have = 61 W/m2K. This is beneficial in the predesign stage of PCM-based thermal energy storage units.

Improved Correlation for Natural Convection Heat Transfer From Inclined Cylinders Having Different Emissivities

1999 ◽  
Author(s):  
Jeffrey C. Stewart ◽  
William S. Janna
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
The Heat Transfer Coefficient

Abstract The purpose of this study was to develop an improved correlation for natural convection heat transfer from inclined cylinders having different emissivities. The angle of cylinder inclination varied from horizontal to vertical in 15° increments. The heat transfer coefficient was obtained experimentally with the cylinder in a state of constant heat flux. Three surface finishes were used in the experiment, which consisted of polished copper, black paint, and aluminum paint. The heat transfer coefficients in all cases varied from 1.21 to 1.65 BTU/(hr·ft2·R) [6.87 to 9.37 W/(m2·K)]. Rayeigh numbers for all experiments varied from 1.31 × 103 to 2.23 × 103. The heat transfer coefficient decreased for each cylinder with an increasing angle of inclination (from horizontal to vertical). The goal of this study was to produce Nusselt-Rayleigh number correlations for each cylinder, and then ultimately produce a single equation that can be applied for all emissivities. The Rayleigh number included a geometry term to account for the inclination of the cylinder. The form of the equation that best represented the data was a power law equation.

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