Preparation And Performance Of Magnesium Sulfate-potassium Sulfate Composite Phase Change Heat Storage Material

In the 21 st century,energy crisis has become a hot issue for all mankind.It is the main content of China's energy transformation to develop new energy instead of traditional energy.Solar energy is the largest green renewable energy source in the natural world and has great potential for development.The phase change materials used in construction field can make full use of the solar wind and other renewable energy to realize the purpose of energy-saving heating.Salt hydrate phase change materials with its cheap,has advantages of high energy storage density in the aspect of building energy efficiency has been widely used,but it is itself there is a problem such as phase separation,supercooling and agglomerate.In this paper,according to the requirements of building energy storage materials using temperature range,the salt hydrate KAL?SO₄?₂·12H₂O and Mg SO₄·7H₂O according to mass ratio 6:4 mixing,after nucleation agent anticaking agent modification effect,were lower super-cooling degree,not agglomeration,good thermal performance and stable cycle performance of new building heating heat storage phase change heat storage material system.Here's the main study:1.According to the application requirements of solar energy building energy storage phase change materials,the analysis and comparison of Na2S2O3·5H₂O and KAl?SO₄?₂·12H₂OMg SO₄·7H₂O salt hydrate?6:4?were conducted.Finally,KAl?SO₄?₂·12H₂O-Mg SO₄·7H₂O salt?6:4?was selected as the research object.2.In order to solve the super-cooling problem of KAl?SO₄?₂·12H₂O-MgSO₄·7H₂O salt hydrate?6:4?,the nucleating agents of sodium tetrabate,Ni SO₄·6H₂O and Mg Cl2·6H₂O were used to improve the treatment.Results showed that 3% Mg Cl2·6H₂O to KAl?SO₄?₂·12H₂OMg SO₄·7H₂O salt hydrate modification effect is best,the optimized salt hydrate super-cooling degree is 1.2 ?,phase transition temperature in 51? or so,phase change materials after 50 times melt-solidification stable cycle performance.3.To solve the problem of the agglomeration of KAl?SO₄?₂·12H₂O-Mg SO₄·7H₂O salt hydrate?6:4?,the anticaking agent such as inert powder calcium carbonate,alumina,calcium oxide and surfactant sodium dodecyl benzene sulfonate,polyacrylamide and hexadecyl trimethyl ammonium bromide were used to improve the hydration salts of KAl?SO₄?₂·12H₂O-Mg SO₄·7H₂O?6:4?,and compared the effects of inert powder and surfactant on the modification of hydration salts.Studies have shown that the use of a 0.3% of 16 alkyl ammonium bromide and a 0.8% of sodium diphenyl sulfonate is used to make the best anti-clotting effect of hydration salt.After optimization of the sample by 200 melt-solidification cycle does not appear agglomerate,phase transition temperature range from46.8 ? to 49.2 ?,super-cooling degree ranges from 1.3 ? to 2.5 ?,heat loss rate was8.45%,the stability is good,suitable for use as building energy saving heat storage material.