The Construction And Heat Management Of Interfacial Solar Water Evaporation System

Solar water evaporation can obtain freshwater resources through seawater desalination or sewage treatment without additional energy consumption,thus has a good application prospect.Interfacial solar water evaporation is a new evaporation mode proposed by researchers based on traditional solar water evaporation in recent years.Currently,most of the reported interfacial evaporator designs focus on improving the evaporation rate,while few studies have been conducted on the heat management analysis of evaporation systems.In this thesis,three-dimensional structured evaporators with different light absorption performance,thermal conductivity,and water transport performance have been constructed.The evaporation rate and the temperature in different areas of the evaporation surface were recorded under different solar irradiance intensities.The energy analysis of the evaporation system and process was carried out using the Dunkle model.The influence of the above factors on the heat loss and energy utilization efficiency of solar water evaporation was studied.The main results and conclusions are as follows.（1）The non-woven fabrics and face towels loaded with graphene and antimony doped tin oxide and the black cotton cloth have significant solar absorption properties,with an absorbance of about 95%.Under certain conditions,the increase in solar intensity significantly increases the evaporation rate.However,the temperature of each region of the evaporation surface increases,resulting in increased heat losses and a decreasing trend in energy efficiency.At the height of 5cm,the evaporator with black cloth wrapped copper sheet delivered an evaporation rate of 1.42 kg·m^-2·h^-1 and an energy efficiency of 89.06%at 1 kw·m^-2 intensity,compared to 2.08 kg·m^-2·h^-1 and65.35%at 2 kw·m^-2 intensity.（2）The thermal conductivity of the evaporator has a significant impact on the evaporation rate.Increasing the thermal conductivity helps to disperse heat to various regions of the evaporation surface,reduce heat losses including conduction,radiation and convection,and thus improve both the evaporation rate and energy efficiency.For the 5 cm high evaporator with black cloth wrapped copper sheet,the evaporation rate(1.42 kg·m^-2·h^-1)and energy efficiency（89.06%）at 1 kw·m^-2 intensity are significantly higher than the evaporation rate(1.27 kg·m^-2·h^-1)and energy efficiency（80.28%）for the evaporator with black cloth wrapped polyester sheet.（3）The higher evaporation rates can be achieved when the material’s water transport capacity matches the evaporator height and sunlight intensity.When the water transport capacity cannot meet the needs,the top temperature of the evaporator becomes too high and the heat loss increases,leading to the deterioration of evaporation performance.The non-woven fabrics in this thesis have better water transport capacity than the black cotton cloth.The evaporation rate of the evaporator with the height of 10cm and black cloth wrapped copper sheet decreases at 2 kw·m^-2intensity compared to that at 1 kw·m^-2 intensity.The evaporation rate of the evaporator with non-woven fabrics wrapped copper sheet continues to increase and reach 2.41 kg·m^-2·h^-1 at 2 kw·m^-2intensity.