Improved film evaporator for mechanistic understanding of microwave-induced separation process

Microwave-induced film evaporation separation process has been reported recently to separate the polar/nonpolar mixture.However,the efficiency of the separation is still too low for practical applications,which requires further enhancement via different strategies such as optimization design of evaporator structure.In addition the depth understanding of the separation mechanisms is great importance for better utilization of the microwaveinduced separation process.To carry out these investigations,a novel microwave-induced falling film evaporation instrument was developed in this paper.The improvement of the enhancement effect of microwave-induced separation was observed based on the improved film evaporator.The systematic experiments on microwave-induced separation with different binary azeotropic mixtures(ethanol-ethyl acetate system and dimethyl carbonate(DMC)-H20 system)were conducted based on the new evaporator.For the ethanol-ethyl acetate system,microwave irradiation shifted the direction of evaporation separation at higher ethanol content in the starting liquid mixture.Moreover,for DMC-H20 system microwaveinduced separation process broke through the limitations of the traditional distillation process.The results clearly demonstrated the microwave-induced evaporation separation process could be commendably applied to the separation of binary azeotrope with different dielectric properties.Effects of operating parameters are also investigated to trigger further mechanism understanding on the microwave-induced separation process.

Dynamic simulation and experimental validation of a two-phase closed thermosyphon for geothermal application

The heat transfer perfonmance of a vertical two-phase closed thermosyphon(TPCT)used in a geothermal heat pump was experimentally investigated.The TPCT is a verticalplain steel pipe with inner diameter of 114 mm and bored 368 m deep underground.Carbon dioxide(CO_(2))is used as working fluid.In the TPCT there is no condensation section.CO_(2)is condensed by the evaporator pf the heat pump,flows into the head of the TPCT and nuns down as a falling film along the inner wall of the pipe.For the heat transfer simulation in the TPCT,a quasi-dynamic model in which the mass transfer between the liquid and vapor phases as well as the conduction heat transfer from the surrounding soil towards the pipe is treated dynamically.However the film flow modeling is based on the Nusselt theory of frilm condenssation.The compauison of the experimental data with the numerical simulation is presented and discussed.