Enthalpy of fusion prediction for the economic optimisation of salt based latent heat thermal energy stores

dc.contributor.authorBadenhorst, Heinrich
dc.contributor.authorBöhmer, Thomas
dc.date.accessioned2018-11-26T06:18:35Z
dc.date.issued2018-12
dc.description.abstractThermal energy storage represents a cost-effective means of integrating variable, renewable resources into the energy mix. The utilisation of latent heat in addition to sensible can reduce capital costs. To accurately screen the numerous possible ionic salts, accurate enthalpy of fusion predictions are essential. Three possible modelling approaches were considered: enthalpic, regular solution entropic and rigorous entropic. These approaches were combined with different techniques to represent the enthalpy of mixing and the temperature-composition dependence. Ultimately it was found that disregarding the entropy of mixing and assuming an ideal liquid phase, combined with an immiscible solid phase resulted in adequate predictions of the experimental data. The approach can be used to rapidly screen a wide range of components using only pure component properties. It can be further generalised to require only melting temperatures through the use of a modified “Richard’s Rule”. The method was used to economically compare binary and ternary combinations over the range of 290–565 °C. The analysis indicated that ternary eutectic mixtures can achieve storage costs using fine chemicals of around 0.18 ± 0.045 $/kJ, with bulk materials conservatively estimated to cost more than 100 times less at ∼1.8 $/MJ. This assumes that storage is achieved through a combination of latent and sensible heat. A set of eight suitable salt candidates were identified that require detailed thermal studies. Lastly it was demonstrated that the use of non-eutectic mixtures, using for example LiNO3 and KCl, may hold the key to bulk storage costs as low as 0.045 $/MJ, if the issues facing practical implementation can be mitigated.en_ZA
dc.description.departmentChemical Engineeringen_ZA
dc.description.embargo2019-12-01
dc.description.librarianhj2018en_ZA
dc.description.urihttps://www.elsevier.com/locate/esten_ZA
dc.identifier.citationBadenhorst, H. & Böhmer, T. 2018, 'Enthalpy of fusion prediction for the economic optimisation of salt based latent heat thermal energy stores', Journal of Energy Storage, vol. 20, pp. 459-472.en_ZA
dc.identifier.issn2352-152X (online)
dc.identifier.other10.1016/j.est.2018.10.020
dc.identifier.urihttp://hdl.handle.net/2263/67312
dc.language.isoenen_ZA
dc.publisherElsevieren_ZA
dc.rights© 2018 Elsevier Ltd. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Journal of Energy Storage. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in Journal of Energy Storage, vol. 20, no. 459-472, pp. 459-472, 2018, doi : 10.1016/j.est.2018.10.020.en_ZA
dc.subjectEnthalpy of fusionen_ZA
dc.subjectThermodynamic modelen_ZA
dc.subjectThermal energy storage (TES)en_ZA
dc.subjectChlorine compoundsen_ZA
dc.subjectCost effectivenessen_ZA
dc.subjectDigital storageen_ZA
dc.subjectEutecticsen_ZA
dc.subjectForecastingen_ZA
dc.subjectHeat storageen_ZA
dc.subjectLatent heaten_ZA
dc.subjectLithium compoundsen_ZA
dc.subjectMixingen_ZA
dc.subjectMixturesen_ZA
dc.subjectNitrogen compoundsen_ZA
dc.subjectPotassium compoundsen_ZA
dc.subjectStorage (materials)en_ZA
dc.subjectEconomic optimisationen_ZA
dc.subjectEnthalpy of mixingen_ZA
dc.subjectPure-component propertiesen_ZA
dc.subjectRenewable resourceen_ZA
dc.subjectTemperature compositionen_ZA
dc.subjectCost benefit analysisen_ZA
dc.titleEnthalpy of fusion prediction for the economic optimisation of salt based latent heat thermal energy storesen_ZA
dc.typePostprint Articleen_ZA

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