Browsing by Keyword "CSP"
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Item A precise method to measure the specific heat of solar salt-based nanofluids(2017-08-01) Muñoz-Sánchez, Belén; Nieto-Maestre, Javier; Imbuluzqueta, Gorka; Marañón, Izaskun; Iparraguirre-Torres, Iñigo; García-Romero, Ana; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; SISTEMAS FOTOVOLTAICOS; Alimentación SostenibleA novel material has been developed for thermal energy storage at high temperatures (>300 °C) with enhanced thermal transport and storage properties. It is considered more efficient than the current molten salts used in the concentrated solar power plants. It is composed of an inorganic salt doped with a small percentage of nanoparticles (NPs), which are claimed to increase the specific heat compared with that of the raw salt. Thus, a precise determination of this thermal property is essential to perceive this enhancement. The specific heat of solar salt (SS) and a mixture of SS with 1 mass% of alumina NPs have been measured by the differential scanning calorimetry (DSC) technique. An isothermal procedure based on modulated DSC has been established to perform the measurements. The influence of the type of crucible, the amount of sample inside the crucible and the presence of moisture on the scattering of the data has been studied. Reliable results with a low uncertainty (<10%) were achieved by the use of T-zero aluminium hermetic crucibles, the mass increment of analysed sample (30 mg) and the absence of moisture inside the crucibles.Item Rheology of Solar-Salt based nanofluids for concentrated solar power. Influence of the salt purity, nanoparticle concentration, temperature and rheometer geometry(2018-03) Muñoz-Sánchez, Belén; Nieto-Maestre, Javier; Veca, Elisabetta; Liberatore, Raffaele; Sau, Salvatore; Navarro, Helena; Ding, Yulong; Navarrete, Nuria; Juliá, J. Enrique; Fernández, Ángel G.; García-Romero, Ana; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOSSolar Salt-based nanofluids have attracted significant scientific interest in recent years due to their improved thermal properties, making them strong candidates as thermal energy storage materials and/or heat transfer fluids in CSP plants. There have been reports on increased specific heat due to the addition of nanoparticles, however, there is a lack of comprehensive information on other essential properties affecting the heat transfer, such as the viscosity. This article concerns the rheological behaviour of nanofluids made of Solar Salt (mass percentage at 60% NaNO3 – 40% KNO3) as the base fluid and silica or alumina nanoparticles as additives. The evolution of these nanofluids viscosity as a function of the shear rate (1–1000 s−1) at a temperature range of 250–400 °C was measured and analysed. The impact of the salt purity (refined or industrial grade), the nanoparticle concentration (0.5–1.5 wt%) and the rheometer measuring configuration (coaxial cylinder or parallel plate) are examined. The results showed in general a Newtonian behaviour of the nanofluids with independency of the rheometer configuration. The relationship between the viscosity and the temperature follows an Arrhenius model. The influence of the nanoparticle concentration on the viscosity of the refined grade Solar Salt is analysed according to the Maron-Pierce and Kriegher-Dougherty models for the nanofluids containing alumina and silica nanoparticles respectively, due to their different shape.