Intensification of fluiddynamic and thermal performance of thermosiphon reboilers

The potential benefit of hiTRAN® tube inserts for fluiddynamic as well as heat transfer intensification of thermosiphon reboilers was investigated experimentally. Circulating flow expressed as single phase tube inlet velocity is regarded as primary criterion for fluiddynamic behaviour while product side heat transfer coefficient represents heat transfer performance. Pure water and a 29 mol% glycerol/water mixture were used as test fluids. Fluiddynamic as well as thermal performance of the bare tube vs. five inserts with different loop volume fractions were determined in a single tube lab-scale thermosiphon reboiler. It was found that most beneficial use appears for the glycerol/water system at low driving temperature difference between service and product side employing inserts with a loop volume fraction around 3%. In best cases a more than 50% increase of the product side heat transfer coefficient was obtained.