A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several operating conditions on the productivity and thermal efficiency of the column were investigated. The results show that both the productivity and thermal efficiency of the column enhance with the elevation of the inlet water temperature. The flow rates of water and carrier gas both have optimal operating ranges, which are 10-30 kg·h^-1 and 4-7kg·h^-1 for the present column, respectively. Meanwhile, the increase of external steam flow rate will promote the productivity of the column but reduce its thermal efficiency.
The modelling and experimental investigation of a thermally coupled humidification-dehumidification desalination process using a carbon-filled-polypropylene shell-tube column are presented.A heat/mass transfer model is established to study the correlation among productivity,thermal efficiency,physicochemical parameters (gas/liquid phase temperature,heat/mass transfer coefficient,Reynolds number etc.),and operating conditions(the temperature of feed water,the flow rates of external steam,feed water,and carrier air);at the same time,the effects of operating conditions on the productivity and thermal eficiency of the column are investigated both theoretically and experimentally,which indicate that the optimum flow rates of external steam,feed water,and carrier gas are 0.18,60,and 10kg.h- 1,respectively,and the higher the feed water temperature(≤95℃)is,the greater the productivity and the thermal efficiency will be.Furthermore,performance comparison with the previous study shows that the condensate productivity of this carbon-filled-plastic column is not lower than that of the copper column,which demonstrates the practicability and feasibility of applying such a plastic column to the humidification-dehumidification desalination process.
Based on the synthesis of DDS in fluidization bed,a new method that can remarkably enhance reactivity and selectivity of the copper-silicon contact mass is investigated experimentally. DDS is produced from silicon and methyl chloride at about 300?℃in the direct synthesis process. The catalyst used in this reaction system is active cuprous chloride powder,which usually forms conglomeration of powder. The conglomerate of catalyst is known to be harmful to the synthesis reaction. Treated by ultrasonic energy,conglomeration of active cuprous chloride catalyst is destroyed,so as to achieve better proportioned dispersion of silicon and catalyst powder. By this means, CuCl catalyst is distributed evenly on the surface of silicon powder, thereby reaction activity and selectivity are increased in the synthesis process of DDS. Using ultrasonic dispersion achieves the same reaction activity with smaller catalyst dosage than the normal dispersion method.
