HEAT TRANSFER ENHANCEMENT AND AIR POLLUTION REDUCTION OF EXHAUST GAS STREAM THROUGH SWIRLING RECUPERATOR JOINED WITH A CYCLONE-SCRUBBER

Abstract

In the present work, the heat transfer enhancement and air pollution reduction of exhaust gas stream through swirling recuperator fitted with a cyclone-scrubber are investigated respectively. The scrubbing works via the contact of target compounds or particulate matter with the scrubbing solution. Solutions were the water and the liquid solution (sodium carbonize + lemon salt) respectively. The results are compared with the same one with plain tubes recuperator. The twisted – tapes is optimized at twist ratios Y = 0.59 for the outer tube and Y = 0.74 for the inner tube. The rod of twisted tape is fixed on bearings to reduce pressure drop by the rotation. The experiments were carried out at Reynolds number from 8000 to 35000 of cold air enters the heat exchanger at 20oC while the hot gases enter at 700 oC. The experimental results indicated that the increase in heat transfer rate of the swirling flow is greater than its respective value of plain flow . The maximum mean Nusselt number increased by 181% than that of plain tube recuperator. The effects of the twisted tape on the heat transfer enhancement efficiency are also investigated. In the other side, the pollution of exhaust gases is greatly reduced by passing exhaust gases into cyclone-scrubber . The results indicated that the concentration of the poisonous gases flow out the cyclone-scrubber decreases by increasing the air velocity. A comparison results between the use of cyclone scrubber by water spray and chemical solution are investigated.