Browsing by Author "Ding, Yulong"
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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.Item Round robin test on the measurement of the specific heat of solar salt(American Institute of Physics Inc., 2017-06-27) Muñoz-Sánchez, Belén; Nieto-Maestre, Javier; González-Aguilar, José; Julia, José Enrique; Navarrete, Nuria; Faik, Abdessamad; Bauer, Thomas; Bonk, Alexander; Navarro, María Elena; Ding, Yulong; Uranga, Nerea; Veca, Elisabetta; Sau, Salvatore; Giménez, Pau; García, Pierre; Burgaleta, Juan Ignacio; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOSSolar salt (SS), a well-known non-eutectic mixture of sodium nitrate (60% w/w) and potassium nitrate (40% w/w), is commonly used either as Thermal Energy Storage (TES) material (double tank technology) or Heat Transfer Fluid (HTF) (solar tower) in modern CSP plants worldwide. The specific heat (cp, kJ kg-1 °C-1) of SS is a very important property in order to support the design of new CSP Plants or develop novel materials based on SS. A high scientific effort has been dedicated to perform a suitable thermophysical characterization of this material. However, there is still a great discrepancy among the cp values reported by different authors1. These differences may be due to either experimental errors (random or systematic) or divergences in the starting material (grade of purity, presence of impurities and/or water). In order to avoid the second source of uncertainty (the starting material), a Round Robin Test (RRT) was proposed starting from a common material. In this way, the different methods from each laboratory could be compared. The study should lay the foundations for the establishment of a systematic procedure for the measurement of the specific heat of this kind of materials. Nine institutions, research centers and companies, accepted the proposal and are contributing with their results. The initiative was organized within the Workshop SolarPACES Task III - Material activity.