EXPERIMENTAL-STUDY OF LAMINAR-FLOW FORCED-CONVECTION HEAT-TRANSFER INAIR FLOWING THROUGH OFFSET PLATES HEATED BY RADIATION HEAT-FLUX

An experimental study of the steady state laminar flow forced-convecti on heat transfer of air flowing through offset plates located between two parallel plates and heated by radiation heat flux was carried out. The ranges of parameters tested were incident radiation heat fluxes o f 500, 700, and 1000 W/m(2). With Re ranging from 650 to 2560, the inl et air bulk temperatures changed from 18.2 to 70 degrees C and the til ting angel of the unit with the horizontal ranged from 0 to 90 degrees respectively. The results show that the rate of the increase in the l ocal Nusselt number was observed to be proportional with Re up to 1900 , while it became less sensitive over Re range of 1900-2500. Also, in this range of Re, with the inlet air temperature of 20 degrees C, the angel of inclination of the unit has no effect on the local Nusselt nu mber. Increasing the incident radiation heat flux in the case of highe r values of Re leads to a slight decrease in the value of the local Nu sselt number. The effect of the inlet air bulk temperature on the forc ed-convection heat transfer coefficient shows. in the case of the hori zontal position. an increase in the inlet air bulk temperature leads t o slight decreases in the value of the average Nusselt number, while i t leads to a significant decreases in the value of the average Nusselt number as the tilting angle increases up to the vertical position. Th is effect is clearer in the case of Re = 650 rather than Re = 2550. (C ) 1998 Elsevier Science Ltd.