NUMERICAL STUDY OF HEAT TRANSFER IN THE RECEIVER CHANNEL OF A PARABOLIC-TROUGH SOLAR SYSTEM WITH NANOFLUID AS HEAT TRANSFER FLUID
DOI:
https://doi.org/10.32782/mathematical-modelling/2026-9-1-1Keywords:
solar thermodynamic system, tubular receiver channel, nanofluid, mathematical model, numerical algorithm, finite volume methodAbstract
The paper presents an analysis of heat transfer processes in the heat-receiving system of a parabolic-trough solar thermodynamic plant in which a nanofluid based on Syltherm800 silicone oil with Al2O3 nanoparticles is considered as the heat transfer fluid. The study is motivated by the fact that intensifying convective heat transfer in the receiver tube without significant design modifications can improve both the thermal and the overall energy efficiency of the plant. Physical and mathematical models of energy transport are developed for a fluid flow in a cylindrical channel with due regard for the temperature- and concentration-dependent thermophysical properties of the nanofluid. By approximating experimental data, analytical correlations are obtained for the density, specific heat capacity, and thermal conductivity of the base fluid and the nanofluid as functions of temperature and nanoparticle volume fraction. For the numerical solution, an algorithm based on the finite volume method with an implicit scheme is developed and implemented in an in-house Python code. The calculations account for laminar flow, a quadratic velocity profile, and iterative correction of coefficients at each axial step. A series of numerical experiments is carried out for pure Syltherm800 and for the Syltherm800/Al2O3 nanofluid with nanoparticle volume fractions of 3 %, 5 %, and 8 %. Temperature fields along the channel length and radius, as well as the mass-averaged fluid temperature, are determined. The mathematical model and numerical algorithm are verified by comparison with a test problem admitting an analytical solution, and complete agreement is obtained. It is shown that the addition of Al2O3 nanoparticles to the conventional heat transfer fluid increases the effective thermal conductivity and promotes a higher mass-averaged temperature in the channel, which may intensify convective heat transfer. It is substantiated that, with a rational choice of geometric and thermodynamic parameters, the proposed nanofluid can be regarded as a promising option for improving the efficiency of solar energy conversion systems in commercial solar power plants.
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