Energy conditions assessment of a two-phase annular thermosyphon used as heat supplier for a new pilot-scale falling film distillation unit

Abstract Energy-efficient chemical processes save resources and provide sustainability. Conventional distillation is notably known as an energy-intensive process, which motivated our research group to develop a new thermosyphon-assisted falling film distillation apparatus (Destubcal technology), where heat is supplied through the condenser of an annular thermosyphon coupled to the distillation tube. From this new design, two possible configurations of energy supply were studied: isothermal and temperature-profile conditions in the condenser of the annular thermosyphon. The distillation tube was fed with ethanol-water mixture, varying the feed flow rate and feed temperature, as well as the power of electrical resistances in the evaporator of the annular thermosyphon. Temperature-profile condition leads to a better heat transfer distribution, resulting in higher temperatures in the distillation tube and so higher ethanol recovery in the distilled product. In this way, temperature-profile operation proved to be more advantageous for this new thermosyphon-assisted distillation unit, corroborated by the separation factor, reaching a 10.3% increase. The analysis of operational variables showed that smaller potencies in the evaporator allow better separation, an important aspect of energy intensification. Thereby, this works contributes towards the urgent demand for novel thermal intensified proposals, indicating the best operational conditions for an advanced falling film distillation unit.