Experimental And Theoretical Study On Enhanced Seawater Evaporation By Solar Chimney

Solar chimney and sea water solar desalination has been research hotspots foryears. But it is not feasible at technology or economical efficiency. The combinedsystem utilizing seawater by solar chimney was put forward basing on these twotechnologies, which enhances seawater evaporation by solar chimney, forms highspeed airflow at the base of chimney, gains fresh water by condensation. The waterand remaining heat by condensation is used to generate electricity. It is an economicfeasible system that can bring fresh water and produce electricity by water or wind.The process of enhanced sea water evaporation using solar chimney was studiedby experiment and theory in this paper. Firstly the effect on enhanced evaporation bytemperature,velocity of airflow and porous materials was studied independently. Twomini-type experimental equipments were founded, the temperature rise,moisturecontent and other conditions were studied. For the shortage of heat storage capacity,the mini-type system cannot work during night and cloudy day. The mid-typeexperimental equipment was set up, temperature rise,moisture content of the airflowand the water of heat storage was studied in sun and cloudy day. In order to go deepinto the heat transfer mechanism in system, we have researched on the heat network insystem. For the sake of learning the law of micro heat transfer and mass transfer, tofind the theoretical basis on system of scale-up, numerical simulation was carried outby Fluent.In enhanced sea water evaporation experiment, the temperature is the main factoraffecting water evaporation, high temperature rise can get high speed evaporation, itwas helpful for evaporation when the velocity of airflow was control in certain scope,at last evaporation also affected by the property,number of the porous materials andthe placed position. The mini-type experimental equipment of solar enhanced seawater evaporation system show that the moisture content of the airflow was little, theairflow was saturation when porous materials was put in. The mid-type experimentalequipment indicated that there were more vapor in airflow and the water have a highheat storage capacity by which the system can work in night and cloudy day, there arealso temperature difference in water at horizontal and elevation direction. The analysisof the system heat network shows that the heat loss by evaporation is more than theheat of airflow temperature rise, the radiation between collector and sky and theconvection between collector and ambient is the main loss of heat in system. At lastthe numerical simulation show that there are higher temperature rise and moisturecontent than experiment for some hypothesis of the model, the circular systemforecasted has a better capability than mid-type experiment.