scholarly journals Numerical Determination of Effects of Wall Temperatures on Nusselt Number and Convective Heat Transfer Coefficient in Real-Size Rooms

2013 ◽  
Vol 5 ◽  
pp. 287963 ◽  
Author(s):  
Ozgen Acikgoz ◽  
Olcay Kincay
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Numerical Determination ◽  
Real Size

Convective Heat Transfer Coefficient and Pressure Drop of Al2O3-Water Nanofluid in a Single-Phase Microchannel for Cooling of High Heat Output Devices

2008 ◽  
Author(s):  
Guillermo E. Valencia ◽  
Miguel A. Ramos ◽  
Antono J. Bula
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Heat Output ◽  
Flux Boundary Condition

The paper describes an experimental procedure performed to obtain the convective heat transfer coefficient of Al2O3 nanofluid working as cooling fluid under turbulent regimen through arrays of aluminum microchannel heat sink having a diameter of 1.2 mm. Experimental Nusselt number correlation as a function of the volume fractions, Reynolds, Peclet and Prandtl numbers for a constant heat flux boundary condition is presented. The correlation for Nusselt number has a good agreement with experimental data and can be used to predict heat transfer coefficient for this specific nanofluid, water/Al2O3. Furthermore, the pressure drop is also analyzed considering the different nanoparticles concentration.

Determination of the Effect of Wall Heating Systems on Convective Heat Transfer Coefficient in Buildings

2014 ◽  
Vol 875-877 ◽  
pp. 1630-1636 ◽  
Author(s):  
Ozgen Acikgoz ◽  
Olcay Kincay ◽  
Zafer Utlu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Energy Consumption ◽  
Thermal Comfort ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Heated Wall ◽  
Real Size

Decreasing energy consumption and advancing thermal comfort are the most important aims of building engineering. Previously reported studies by many researchers have found that different usages of convective heat transfer coefficient (CHTC) correlations in heating system simulations have considerable impacts on calculated heating load in buildings. Hence, correct utilization of CHTCs in real size room enclosures has great importance for both energy consumption and thermal comfort. In this study, a modeled room was numerically heated from one vertical wall and cooled from the opposite wall in order to create a real room simulation. While cooled wall simulate heat losses of the room, heated wall simulates the heat source of enclosure. Effects of heated and cooled wall temperatures and characteristic length on CHTC and Nusselt number in the enclosure were numerically investigated for two (2-D) and three dimensional (3-D) modeling states. CHTCs and Nusselt numbers of a real size room with the dimensions of 6.00 by 2.85 by 6.00 were found with FLUENT CFD and graphics of change were drawn. As result, difference between 2-D and 3-D solutions was found approximately 10%. This was attributed as the effect of air flow pattern effects over other surfaces in the enclosure that can not be counted at 2-D solutions. The change of CHTC at different characteristic lengths was illustrated as well.

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