Numerical determination of the heat transfer coefficient for volumetric air receivers with wire meshes

• Published in: Solar energy 2018-03, Vol.162, p.317-329
• Main Authors: Avila-Marin, Antonio L., Caliot, Cyril, Flamant, Gilles, Alvarez de Lara, Monica, Fernandez-Reche, Jesús
• Format: Article
• Language: English
• Subjects: Air flow; Boundary conditions; Chemical and Process Engineering; Computer simulation; Convective heat transfer; Convective heat transfer coefficient; Correlation analysis; Detail simulation; Engineering Sciences; Finite element method; Heat transfer; Heat transfer coefficients; Mathematical models; Porosity; Receivers; Screens; Simulation; Solar energy; Temperature profiles; Volumetric absorbers; Wall temperature; Wire cloth; Wire mesh
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2018.01.034

•The convective heat transfer behavior is driving by the specific surface area.•Meshes with different porosities and similar surface area have similar heat transfer.•Meshes with similar porosities and different surface area have different heat transfer.•The heat transfer coefficient increases with the specific surface area. Volumetric receivers made of metallic plain-weave wire meshes are a promising technology that could lead to many different designs and configurations. This work deals with the numerical determination of the convective heat transfer coefficient between an air flow and stagger stacked plain-weave wire mesh screens that constitute the volumetric receivers. For that purpose, six geometries are studied with different geometrical characteristics, but with the constraint of finding pairs with similar porosities. The commercial code STAR-CCM+ was used for the detailed geometries for solving the microscopic equations. The numerical methodology, boundary conditions and main assumptions are presented. Based on a parametrical study over the velocity and wall temperature for each analyzed mesh, a correlation of the local volumetric convective heat transfer was found and depends on the Reynolds and Prandtl numbers. The different correlations were compared among them and with literature data showing similar trends and order of magnitudes. One of the correlations obtained was validated by using it in a homogeneous equivalent model assuming a local thermal non-equilibrium between the solid and fluid phases. The results were compared to the temperature profiles computed by a detailed simulation and show a very good agreement.