An Analysis of Combined Free and Forced Convection Heat Transfer From a Horizontal Circular Cylinder to a Transverse Flow

1971 ◽  
Vol 93 (4) ◽  
pp. 441-448 ◽  
Author(s):  
N. D. Joshi ◽  
S. P. Sukhatme
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Circular Cylinder ◽  
Differential Equations ◽  
Surface Temperature ◽  
Convection Heat Transfer ◽  
Transverse Flow ◽  
Convection Heat ◽  
Free And Forced Convection ◽  
Horizontal Circular Cylinder

Combined free and forced convection heat transfer from a horizontal circular cylinder to a transverse flow is analysed for the case when the forced flow is either in the direction of the free convection flow (parallel flow) or in the direction opposite to it (counter flow). The problem is solved for two cases: (1) a specified surface temperature variation and (2) a specified wall heat flux variation along the circumference. A coordinate perturbation method is used to transform the governing set of partial differential equations into a system of ordinary differential equations, which are solved by numerical methods. The numerical work is done for the boundary conditions of constant surface temperature and constant wall heat flux. The variation of local heat transfer coefficient and wall shear stress along the circumference up to the point of separation and velocity and temperature profiles in the boundary layer are obtained for varying values of the governing parameters Gr/Re2 in the constant temperature case (or Gr/Re2 in the constant heat flux case) and Pr.

Design of a Mobile Probe to Predict Convection Heat Transfer on Building Integrated Photovoltaic (BIPV) at University of Technology Sydney (UTS)

2015 ◽  
Author(s):  
Jafar Madadnia
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Simple Technique ◽  
Convection Heat Transfer ◽  
Thermal Design ◽  
Uniform Heat Flux ◽  
Convection Heat ◽  
Empirical Correlations ◽  
Building Integrated Photovoltaic

In the absence of a simple technique to predict convection heat transfer on building integrated photovoltaic (BIPV) surfaces, a mobile probe with two thermocouples was designed. Thermal boundary layers on vertical flat surfaces of a photovoltaic (PV) and a metallic plate were traversed. The plate consisted of twelve heaters where heat flux and surface temperature were controlled and measured. Uniform heat flux condition was developed on the heaters to closely simulate non-uniform temperature distribution on vertical PV modules. The two thermocouples on the probe measured local air temperature and contact temperature with the wall surface. Experimental results were presented in the forms of local Nusselt numbers versus Rayleigh numbers “Nu=a * (Ra)b”, and surface temperature versus dimensionless height [Ts -T∞= c*(z/h)d]. The constant values for “a”, “b”, “c” and “d” were determined from the best curve-fitting to the power-law relation. The convection heat transfer predictions from the empirical correlations were found to be in consistent with those predictions made by a number of correlations published in the open literature. A simple technique is then proposed to employ two experimental data from the probe to refine empirical correlations as the operational conditions change. A flexible technique to update correlations is of prime significance requirement in thermal design and operation of BIPV modules. The work is in progress to further extend the correlation to predict the combined radiation and convection on inclined PVs and channels.

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