Study On Preparation And Properties Of CaCl₂-based Adsorption Heat Storage Materials

The uneven distribution of solar energy in time and space places an urgent need on heat storage technologies that can efficiently store heat in similar temperature ranges.Thermochemical adsorption heat storage uses the chemical bonds formed between substances to store heat.It has the advantages of no adiabatic protection,long storage period,and large heat storage density.It is suitable for cross-season storage of solar energy.Inorganic hydrated salt adsorption heat storage stores and releases heat through the process of inorganic salt absorption and desorption of crystalline water,but excessive adsorption will cause the dripping phenomenon of salt solution outflow,making it difficult to apply to industry.This paper aims to solve the drip phenomenon in the process of thermal storage of inorganic hydrated salt thermal chemisorption.The composite adsorbent is constructed by the method of macropore loading and the carbon material synergistically improving the thermal conductivity.Method for preparing anti-drip material of shell structure.In this paper,the macroporous melamine sponge is used as the substrate to carry calcium chloride inorganic hydrated salt to form CaCl₂@melamine sponge thermochemical adsorption heat storage composite adsorbent.Impact.Thermochemical adsorption experiments show that under the same other conditions,as the ambient temperature increases,the adsorption ratio of the composite adsorbent decreases,as the relative humidity increases,the adsorption ratio of the composite adsorbent increases,and as the impregnation concentration increases,The adsorption ratio of the composite adsorbent decreases.When the ambient temperature is 20℃,the relative humidity is 90%RH,and the impregnation concentration is 10 wt.%,the composite adsorbent achieves the best adsorption effect,and the adsorption ratio is 1.861 g·g^-1.In this paper,the three-dimensional porous carbon foam of vinylidene fluoride was prepared by sacrificial salt template method,and then loaded with calcium chloride to form a CaCl₂@PVDF composite adsorbent,synergistically enhancing the thermal conductivity of the macroporous base material.The microstructure of the composite adsorbent was characterized by scanning electron microscopy,and the effects of ambient temperature and adsorption humidity on the adsorption effect of the composite adsorbent were explored respectively.The thermal conductivity of the composite adsorbent was measured.A desorption experiment was carried out on a solar evaporation test bench.The experimental results show that the salt template method leaves a macroscopic hollow pore structure in the carbon material after the salt is washed away,which can play the role of supporting calcium chloride and containing the salt solution formed after adsorption.The adsorption effect of the composite adsorbent decreases with increasing temperature and increases with increasing relative humidity.The composite adsorbent loaded with calcium chloride has a thermal conductivity of 1.3 W·m^-1·K^-1,which can quickly extract the stored heat.At the end of this paper,we prepared a drip-proof core-shell structure by spraying method,explored the effect of shell coating on the effect of composite adsorption and adsorption,and explored the cycle performance of composite adsorbent.The following conclusions are drawn: the adsorption ratio of perlite supported CaCl₂ experimental group is 1.09 g·g^-1,and the adsorption ratio of perlite supported CaCl₂ shell coating group is 1.01 g·g^-1,that is,the coating of the shell material will adsorb the composite adsorbent The effect has a certain impact,but due to the small impact,it can be ignored.As the coating quality of the shell layer increases,the adsorption ratio of the core-shell composite adsorbent decreases.After ten cycles of adsorption,the composite adsorbent has less salt loss,and the core-shell structure can effectively prevent dripping.