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Notes:
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Nowadays, industrial processes use large quantities of fuel and electricity that produce heat, but much of
which is wasted either to the atmosphere or to water. Many types of equipment have been developed to
re-use some of this waste heat. Waste heat usefulness is determined by its temperature and its exergy;
the higher the temperature the higher the quality or value. There are mainly three reversible methods to
store it: sensible, latent and chemical. In this case, a solid by-product from the potash industry is tested in
two different shapes to be used for industrial sensible heat recovery in high temperature, in a range of
100–200 ºC. This heat recovery could be used for cogeneration, energy efficiency measures, passive heat
recovery, solar cooling, etc. Within all the properties that define the suitability of a material to store sensible
heat, waste materials stand out especially for their low costs and availability. This heat recovery
could be used for cogeneration, energy efficiency measures, passive heat recovery, solar cooling, etc.
For that, a complete analysis of thermophysical properties was done both, at laboratory and a pilot plant
scale. At the laboratory, the material composition was found to be NaCl as major phase. With differential
scanning calorimetry (DSC) the specific heat capacity was determined as 0.738 kJ/kgºC. The thermal stability
was checked from ambient temperature to 800 ºC and the density and the conductivity at room
temperature were also calculated. Also, a corrosion test was performed using samples of stainless steel
at three degradation times, these results were compared with those obtained with Solar salt, a commercial
and extended option for thermal energy storage (TES) applications at high temperature. At pilot plant
scale, using 59 kg of storage material, thermal cycles were performed with the storage material heating
and cooling it from 100 to 200 ºC varying parameters as the heat transfer fluid (HTF) flow rate and the
duration of the cycles.
The work was partially funded by the Spanish Government
(Project ENE2011-22722 and ULLE10-4E-1305). The authors would
like to thank the Catalan Government for the quality accreditation
given to their research group GREA (2009 SGR 534) and research
group DIOPMA (2009 SGR 645), and to Iberpotash. Antoni Gil
would like to thank the Col legi d’Enginyers Industrials de Catalunya
for his research appointment. Laia would like to thank the
Spanish Government for her research fellowship (BES-2012-
051861). |
