Experimental Investigation On Combined Heat Loss Characteristics Of Flat Plate Under Environmental Wind

The investigation on heat loss characteristics of flat palte is widely used in estimation for heat loss of solar utilization device,such as flat-plate solar collector and photovoltaic cell panel,etc.By establishing wind tunnel and employing electrical heating method,this article explored the heat loss of flat plate under wind condition.Both the uniform and no-uniform heat flux boundary conditions were adopted,and under these conditions,the temperature and heat loss of plate surface were compared first.Then the impacts of tilt angle ?,wind incidence angle ?,wind speed V and heat flux qwm on heat loss were explored.The results show that,when ? is small,there are two maximum values of convection heat transfer coefficients h_cx under nonuniform boundary condition.As for average radiation Nusselt number Nurm and average convection Nusselt number Nu_cm,differences between the two boundary conditions seem indistinctive.At windward orientation,average radiation Nusselt number Nurm and average convection Nusselt number Nu_cm are not sensitive to ?.While for leeward orientation,the average radiation Nusselt number Nurm is increasing with the increasing ?,however,the average convection Nusselt number Nu_cm is decreasing with the increasing ?.At large wind speed,the radiation heat loss and the convection heat loss are dominant in the total heat loss.While for low wind speed,the convection heat loss plays a domiant role in the total heat loss,at this time,the higher qwm is not conductive to convection heat loss,which will cause a even higher operating temperature.Both the radiation heat loss and the convection heat loss are effected by tilt angle ?,wind incidence angle ?,wind speed V and heat flux qwm,but the variations of average radiation Nusselt number Nurm and average convection Nusselt number Nu_cm are opposite with various parameters.In addition,the uncertainty analysises of experimental data and analysis results were investigated to ensure the creditability in this article.By regression analysis,new correlations of average radiation Nusselt number Nurm and average convection Nusselt number Nu_cm have been developed.