Investigation of energy storage properties of borax

In this thesis, energy storage and pumping facilities of borax decahydratewere investigated. Samples were obtained from Eti Mine Works. Latent energystorage properties and sensible energy storage capacity of borax have been foundby using classical thermal heating, microwave heating and calorimetric methods.Variation of reaction in which borax dehydrate reacted with water, versusactivation temperature were investigated. Energy stored samples reacts with liquidwater to give back energy. Under normal conditions water vapor not react withactivated borax decahydrate, whereas the hydration reaction given in vacuum atlow pressure for the cooling process should be run was deduced.As a result of dehydration and hydration of borax samples were comparedwith borax pentahydrate and borax decahydrate respectively. For this purpose,TGA, DTA, DSC thermal, imaging techniques such as XRD crystallographicanalysis and SEM were used. As a result of these analysis, the borax-waterreaction occurred as a reversible and borax can be used for renewable energystorage materials.Thermokinetic analysis of the solid-gas reaction by using boraxdecahydrate TGA data with Coats-Redfern and Arrhenius models wasinvestigated and the activation energy, frequency factor, reaction rate weredetermined. Volumetric energy storage capacity of borax were calculated andcompared with common several energy storage materials.Finally thermochemical properties of borax-water heat pump system,evaporation enthalpy of the system, running temperature and pressure range havebeen determined from plotted lnP-1/T graph. To test energy storage and pumpingproperties, experimental apparatus was established according to determinedconditions and the borax-water system cooled from room temperature to 2 oC wasachieved.