Preparation,Characterization And Heat Storage Study Of Sulfate Based Inorganic Hydrous Salt And Composite Materials

An environmental friendly and sustainable energy supply is one of the major challenges of the recent century.In this context,it is dedicated to contribute to the development of materials for thermochemical energy storage of sulfate base inorganic hydrous salt and composite materials,which is to improve the efficiency of energy production and utilization.The overall goal of this dissertation is to provide insights into the interrelations of the underlying mechanisms of thermochemical charging and discharging in to the bulk scale performance of sulfate base inorganic hydrous salt and composite materials.Following work has been done:?1?The dynamic properties of three salts,i.e.,zinc sulfate,magnesium and iron salts,were investigated based on their hydration and dehydration characteristics.Four sets of temperatures were used to investigate the effect of regeneration temperatures on the physiochemical properties of the materials.At 100 ?,zinc sulfate showed a significant loss of water as compared to magnesium and iron salts,while in the hydration process at lower temperatures,zinc sulfate showed the highest sorption enthalpy and energy density.The results together indicated that zinc sulfate is more energy efficient than the other sulfates totally.?2?MgSO₄/ZnSO₄?MZx?composite is prepared to improve the hydration enthalpy and water uptaking ability of heat storage material further.The result shows that 9:1 of MgSO₄ and ZnSO₄?MZx?showed better hydration behavior and MZx composite was 34 and 48% improved than its counterparts respectively.The effect of humidity and temperature on adsorbed mass was studied under constant temperature and humidity.The result showed that the MZx composite adsorbed its maximum?0.21 g/g?water mass at 75% humidity under 45 ?.?3?Composite ZnSO₄?7H2O-zeolite is prepared to improve hydration performance by impregnation method with zeolite matrices?13X-zeolite and LTA-zeolite?.The composite of ZnSO₄/13X-zeolite showed highest water sorption?0.26 g/g?at 75% relative humidity under 45 oC air temperature,which is double than pure ZnSO₄?7H2O due to larger surface area?491 m2 g-1?and pore volume?0.31 cm3?.Furthermore,both hydration rate and adsorption mass dependence on relative humidity and hydration temperature are studied.When the air temperature and the relative humidity are higher than 45 oC and 75% RH,the hydration ability of the composite material is significantly reduced.Besides,X?ray measurements of composite?ZnSO₄/13X?revealed that sorption/desorption process,crystallinity and phase of partially hydrated ZnSO₄ remain the same,which enhance the adsorption mass and enthalpy during the hydration process.?4?A novel composite of two dimension layered MXene and salt hydrate is used to form magnesium sulfate heptahydrate/2D carbide?MgSO₄/MXene?composite to improve the thermochemical heat storage performance of magnesium sulfate heptahydrate.A novel 2D MXene-based composite improves the performance in hydration?2167 J/g?/ dehydration enthalpy?2278 J/g?,better heat conductivity,good cyclicability,maximum water sorption performance and larger thermal energy conversion under sunlight.The composite result showed better radiation absorber and 45% long-time back up than pristine MgSO₄ salt.The water sorption performance of composite showed highest water sorption than MgSO₄,which was attributed to the wider interlayer spaces in MXene nanosheets.All the result concluded that the resultant MgSO₄/MXene has excellent long-term thermal energy storage,photo-tothermal conversion and larger water sorption performance,which demonstrates that the asprepared composite is a promising candidate for thermochemical heat storage applications.The findings in this dissertation provide an important contribution to the understanding of the mutual interrelations and to research in this field as well as to the increase of the overall level of technological readiness of materials for thermochemical energy storage.