Study On Preparation And Properties Of Sodium Thiosulfate Petahydrate Phase Change Heat Storage Materials

The building field is a high energy consuming field, which accounts to one third of the totalsocial energy consumption, and the heating, air conditioning energy consumption and totalventilation account for more than60%of the total energy consumption of buildings. A kind ofcomfortable、clear and security heating way is needed in life and work. Regenerative floorwith phase change material is the best one heating way. Phase change thermal storage canease the energy shortage situation in time and space. The phase change material which isfilled in building materials is made into floors, ceilings, walls, etc., and then used for heatingbuildings. The low power or solar energy can be used as the heat source, and they can notonly improve energy efficiency, achieving green energy, but also regulate the indoortemperature of buildings, then to provide a comfortable environment for study and work.Sodium thiosulfate pentahydrate (Na2S2O35H2O) has a high phase enthalpy, its phasetransition temperature is48oC, due to that it is suitable for a radiant floor heating heat storagematerial. In order to solve its problems of supercooling and phase separation, according toEdison rule, this paper chooses a variety of additives on modified sodium thiosulfatepentahydrate to prepare for a radiant floor heating phase change thermal storage material, andthe material properties of the PCMs were tested and analyzed..Na2S2O35H2O was modified by the four nucleating agents, MnCl2,Na2H2P2O7,CaSO42H2O, naphthol, and the three thickening agents, carboxymethyl cellulose (CMC),activated clay, solvable paraffin with different composition and ratios. The results indicatethat (1)5.0%MnCl2and2.0%activated clay,0.083%Na2H2P2O7and3.0%activatedclay,0.083%Na2H2P2O7and solvable paraffin（the ratios of solvable paraffin are0.5%to5.0%），5.0%CaSO42H2O and activated clay(the ratios of activated clay are0.5%to5.0%）0.5%naphthol and0.5%NaCl, all produce good effects in the modification of Na2S2O35H2O.(2) All the modified sodium thiosulfate pentahydrate could begin to crystallizeand releasethermal energy at above30oC. The highest exothermic temperature varied from43to48oCand with an exothermic duration ranging from40to80min, and some even more than80min.The phase change enthalpy of modified Na2S2O35H2O varies from176to210J/g, while nophase separation occurs in the thermal storage/release process.(3) With the experimental device, the best heat storage temperature of modified sodium thiosulfate pentahydrate phasechange thermal storage material is70oC, and the optimum heat storage time is1h.