HEAT-TRANSFER ENHANCEMENT IN A VERTICAL CHANNEL WITH ASYMMETRIC ISOTHERMAL WALLS BY LOCAL BLOWING OR SUCTION

In this article, local heat transfer enhancement in a vertical paralle l channel with asymmetric isothermal walls is numerically investigated . A porous wall segment is embedded in the hot wall to achieve this en hancement. By assuming the reference pressure and temperature on the o ther side of the hot wall, the heat transfer is enhanced as hot fluid is sucked from the channel. The heat transfer improvement is a local e ffect that becomes more effective with the increase of porosity and th e distance measured from the entrance to the position of porous wall s egment, it is shown that the local cooling enhancement is effective in low Reynolds number cases (Re less than or equal to 100) but is less impressive when the Reynolds number is higher. The numerical results a lso show the possibility of embedding multiple porous segments in a si ngle channel, provided that the mass fraction sucked out of the channe l is limited.