(230e) Enhanced Heat Transfer in Vertical Thermosiphon Reboiler

Vertical thermosiphon reboilers play the important role in heat exchange processes and are widely used in various processes. Hydrostatic pressure on the fluid at entrance to tubes causes forming of subcooled zone in vertical thermosiphon reboiler tubes. Since heat transfer coefficients in subcooled zone comparing to boiling heat transfer coefficients are significantly low, the presence of subcooled zone causes the overall heat transfer coefficient in reboiler tubes to be reduced. Appling enhanced heat transfer increase overall heat transfer coefficient inside the tubes of vertical thermosiphon reboilers and significantly eliminates performance problems. In fact heat transfer enhancement decrease the subcooled zone length and surface temperature of tubes which reduce fouling formation in this zone.

In our previous works, we have studied on the effect of using several types of tube inserts in a subcooled zone of a thermosiphon reboiler and in this paper we study on applying some different tube inserts in subcooled zone of a vertical thermosiphon reboiler. Having prepared a simulated model, we studied on the effect of using wire matrix insert, helically coiled Inserts and twisted tape inserts in this model. Finally, effect of these tube inserts on overall heat transfer coefficient, subcooled zone overall heat transfer coefficient, average heat flux rate, maximum temperature of reboiler tube, subcooled zone length and heat transfer surface area in a vertical thermosiphon reboiler have been discussed.