الفهرس 
Heat transfer fluids in the solar heating systemsOnly 14 pages are availabe for public view
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Abstract
There are many fluids that are used in the solar heating systems like air, water, glycol/water mixtures, hydrocarbon oils, thermal oils, molten salts, and others. But most of these fluids have problems.
Proceeding from this, many researches are directed to find suitable heat transfer fluid in order to meet all requirements and to overcome these problems. Ionic liquids are considered a promising solution for most of these problems due to its tuneablity and its excellent thermophysical properties as: High thermal stability, high heat capacity, high ionic conductivity due to its ionic nature, low melting temperature (room temperature), low vapor pressure, and large liquid range. These good properties make the ionic liquids suitable to be used as heat transfer fluids in different applications.
The present work is an experimental investigation of the thermodynamic properties )p,ρ,T( of different ionic liquids at temperature from 283.15 K to 393.15 K and pressure from the atmospheric pressure and up to 100 MPa using a recently developed high pressure – high temperatu¬re vibrating tube densimeter DMA HPM (Anton-Paar, Austria). These ionic liquids are:
-1-Ethyl-3-methylimidazolium Bis (trifluoromethylsulfonyl)imide, [EMIM][NTf2];
-1-Butyl-3-methylpyridinium tetrafluoroborate, [C4mpyr][BF4]; and
-1-Butyl -4- methylpyridinium tetrafluoroborate, [b4mpy][BF4].
In this investigation also a treatment of the obtained experimental results is performed to correlate these results in a form of equation of state. These correlated equations of state are used to calculate the thermal coefficients such as: isothermal compressibility, isobaric thermal expansibility, thermal pressure coefficient, heat capacities difference, and the internal pressure of the fluid.
The error analysis of the measured and calculated properties showed that the uncertainties of the measured density were ± 0.03-0.08 % and the deviation of the calculated densities, from the fitted equation of state, not more than ± 0.01% from the measured values.
The obtained (p,ρ,T) experimental results are included to the Dortmund Data Bank of DDBST GmbH, Germany to be used during the design of industrial products and new technical process.