FREE-CONVECTION HEAT-TRANSFER IN MULTIPLE VERTICAL CHANNELS

Free convection heat transfer in multiple parallel vertical channels w ith isothermal walls is considered in this paper. Systems consisting o f two, three and an infinite number of channels located side by side a nd with aspect ratios (the ratio of channel height to its width) rangi ng from 5 to 20 and for Grashof numbers, based on the channel width, u p to 10(5) were investigated numerically. Results show that the heat t ransfer in a channel is affected by its interaction with the neighbori ng channels, This interaction depends upon the number of participating channels; it increases with an increase of the Grashof number and dec reases with an increase of the distance between the channels. Compared with a single isolated channel, the Nusselt number in the case of a t wo-channel system increases by up to 5% on the channel inner wall (wal l closer to the other channel) and decreases by up to 5% on the channe l outer wall. When an infinite number of channels is present (periodic configuration), the Nusselt number increases by up to 18%. When heat transfer only in the entrance region of the channel is considered (the first 10% of the channel total length), the interaction between the c hannels increases the corresponding Nusselt number by up to 38% on the channel inner wall and decreases it by up to 33% on the channel outer wall for a two-channel system and increases it by up to 48% for the p eriodic configuration. Correlations permitting quick determination of the Nusselt numbers for both configurations are given.