Molten salts (sodium and potassium nitrides) are going to be used in many different plants as heat transferring fluids, e.g.
concentration solar plants, nuclear power plants, etc. In fact they present may important advantages: their absolute safety
and non toxicity, availability and low cost. But their use, e.g. in the energy receiving pipe in the focus of the parabolic
mirror concentrator of the solar thermodynamic plant, requires the accurate knowledge of the thermophysical properties,
above all thermal conductivity, viscosity, specific heat and thermal linear expansion, in the temperature range
200°C÷600°C. In the new laboratory by ENEA Casaccia, SolTerm Department all these properties are going to be
measured.
Thermal conductivity is measured with the standard probe method (linear heat source inserted into the material)
manufacturing a special probe suited to the foreseen temperature range (190-550°C). The probe is made of a ceramic
quadrifilar pipe containing in different holes the heater (Ni wire) and the thermometer (type J thermocouple).
The thermal linear expansion will be measured by a special system designed and built to this end, measuring the sample
dilatation by the reflection of a laser beam by the bottom of the meniscus in the liquid solid interface.
The viscosity will be evaluated detecting the start of the natural convection in the same experiment as to measure thermal
conductivity.
In the paper the construction of the devices, the results of preliminary tests and an evaluation of the obtainable accuracy
are reported.
The method for contemporary measuring thermal conductivity, thermal diffusivity and thermal contact resistance up to
1500°C has been assessed. First the heat propagation model has been developed to be used in least square procedure to
process temperature data and give the best estimate on the unknown parameters. Second special devices to be used in the
experimental procedure have been designed and built or are going to be built. In the meanwhile ambient temperature
tests on bricks have been carried out to establish the data processing procedure, and to recognize the experimental
troubles likely to be found. These tests shows that the experimental data well follow the theoretical prediction, the
thermophysical parameter can be evaluated with good accuracy, and that care must be taken to satisfying the theoretical
assumptions on the base of the model, and to accurately process data for taking into account mutual dependence of the
parameters.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.