Experimental Investigation On Heat Dissipation Of Inclined Rectangular Enclosure With Glass Cover Under No-wind Condition

Heat dissipation in partitioned and non-partitioned rectangular enclosures formed by quartz glass cover and base plate made of composite stone was experimentally investigated.Under no-wind condition,the enclosure was heated electrically from bottom,which changes in a linear way.Internal and external combined heat transfer coefficients h_in and h_ex of enclosure,total thermal resistance R_tot of heat dissipation and correlations of average radiative and convective heat loss Nusselt numbers outside the glass cover were obtained and discussed with different gradient parameter k,magnitude of heat flux and tilt angle.Also,the experimental phenomena were compared between partitioned and non-partitioned conditions.Relevant results are written as followed:For non-partitioned condition,h_ex for k=0 is higher than k=0.2,while the effect of k on h_in is not regular.For different tilt angles,h_in is higher than h_ex under smaller tilt angle??<60°?,but h_ex may exceed h_in for bigger tilt angle.Average convective heat loss Nusselt number Nu_cm increases with the augment of tilt angle under the same condition.For partitioned condition,both h_in and h_ex for k=0 are higher than those for k=0.2,meanwhile,h_in is always higher than h_ex for any tilt angles,the variation of h_in and h_exx under different angles is not obviouse.Nu_cm for?=60°shows a relative irregularity when k=0 and k=0.1,while Nu_cm increases with the augment of tilt angle for k=0.15 and k=0.2.Local temperature differences?t_l-t_a?on the base plate and glass cover change in the same regularity for both non-partitioned and partitioned conditions,while the impacts of partitions on mean temperature on glass cover is greater than that on base plate.Compared with non-partitioned condition,R_in is decreased,R_ex is increased and R_tot is higher when tilt angle?<60°for partitioned condition,which means that heat transfer in the enclosure can be effectively suppressed by attaching fins on the internal glass cover.For both non-partitioned and partitioned conditions,R_tot for non-uniform heat flux boundary condition is higher than that for uniform heat flux boundary condition.Besides,for partitioned condition,Nu_cm on the glass cover is smaller,on the contrary,Nu_rm is bigger when compared with non-partitioned condition.Under different gradient parameter k,heat flux and tilt angle,empirical correlations for partitioned and non-partitioned conditions are developed to quantitatively characterize heat transfer outside the glass cover.The fitting correlations have a good agreement with experimental result,which can be useful in engineering applications.From the four correlations,it should be noted that Nu_cm is comprehensively influenced by parameters such as k,?and Ra^*,while the effect of?for Nu_rm is less pronounced when compared with k and Ra^*.