Study On The Characteristics Of Interfacial Photothermal Evaporation And Thermoelectric Generation Via Porous Polyvinylalcohol Hydrogel

Solar-driven interfacial water evaporation can efficiently produce freshwater resources and reduce the use of fossil fuels,providing an effective way to achieve the goal of"emission peak and carbon neutrality".At present,unstable operation and insufficient energy utilization in high concentration brine hinder its development and application.In this paper,carbon-based Polyvinyl alcohol（PVA）hydrogel photothermal material is taken as the research object.Based on pore structure regulation,evaporation rate and stability of evaporator are improved.To solve the problem of insufficient energy utilization,thermoelectric generation synchronously produces clean water steam and electric energy to improve the utilization rate of solar energy.Will have good biological compatibility,excellent hydrophilicity and mechanical properties of PVA hydrogel and has full-spectrum absorption properties of carbon nanotubes,the combination of fermentation by yeast,the freeze-thaw cycle of the aperture of adjustable carbon-based prepared PVA hydrogel,characterization analysis for carbon-based PVA hydrogel solar-driven interfacial water evaporation related physical parameters.A preparation method of carbon-based PVA hydrogel with good optical absorption rate（95.6%）,capillary water transport performance and adjustable pore size in the range of 0.53–1.47 mm was obtained.A solar-driven interfacial water evaporation device was constructed.The evaporation rate was taken as the evaluation index,and the water supply and demand balance relationship of the evaporation front of the optical solar absorber was realized.The water evaporation rate of 1.64kg·m^-2·h^-1was achieved at 1 sun.The local thermal effect was verified by numerical simulation,and the energy transfer problem in the interface photothermal evaporation process was analyzed.Combined with the temperature image,the heat loss of the solar absorber during operation is calculated,which provides the basis for the subsequent optimization research.In the near-saturated saline with 25%Na Cl concentration,its salt tolerance and long-term stability were verified by 6 h continuous experiment,which provided a new idea of salt resistance balance for the development of solar-driven interfacial water evaporation technology.Considering the reuse of the surface energy of the solar absorber,a thermoelectric generation device was introduced into the solar-driven interface water evaporation system,and the heat transfer from the evaporation front to the hot end of the thermoelectric generation device was enhanced through structural optimization.The optical concentration,brine concentration and cooling water temperature as the influencing factors,the interfacial water evaporation and thermoelectric generation performance composed of the two-dimensional solar absorber are discussed.The results show that the evaporation rate reaches 4.51 kg·m^-2·h^-1and the output power density reaches 1.2 W·m^-2at 4 sun,realizing the reuse of surplus energy in the solar-driven interfacial water evaporation.