Solar receivers

Concentrated solar power (CSP):

CSP systems use mirrors or lenses to concentrate a large area of solar radiation onto a receiver with a small area. Electrical power is produced when the concentrated solar radiation is converted to heat, which drives a heat engine (usually a steam turbine) connected to an electrical power generator

Solar Towers:

In a solar tower plant, solar radiation is reflected and concentrated by a field of mirrors into a receiver situated at the top of a tower. This energy is transferred to a working fluid which is used to drive a power cycle. The design of the receiver is critical for the performance of the solar plant. CTTC has been working in the development of advanced numerical models for solar tower receivers, that include several phenomena such as: conduction in the metals and insulation materials, solar and thermal radiation heat transfer, working fluid flow and heat transfer (one or two-phase flows), turbulent natural convection between the receiver and the surrounding air, etc.

Related Publications:

Colomer, G.; Chiva, J.; Lehmkuhl, O.; Oliva, A. "Advanced CFD&HT numerical modeling of solar tower receivers", Proceedings of SolarPACES 2013

Chiva, J.; Lehmkuhl, O.; Oliva, A. "Detailed numerical model for the receiver of a solar power tower plant", Proceedings of SolarPACES 2012, http://cms.solarpaces2012.org/proceedings/paper/61267110534

Chiva, J.; Lehmkuhl, O.; Borrell, R.; Oliva, A. "Direct numerical simulation of the turbulent natural convection flow in an open cavity of aspect ratio 4", Proceedings of the 7th International Symposium on Turbulence, Heat and Mass Transfer 2012, ISBN 978-1-56700-301-7

Chiva, J.; Lehmkuhl, O.; Soria, M.; Oliva, A. "Modelization of heat transfer and fluid dynamics in solar power towers", Proceedings of ISES Solar World Congress 2011, pp. 629-634

Chiva, J.; Soria, M.; Oliva, A.; Lehmkuhl, O. "Turbulent natural convection in an open cavity: a numerical study", Proceedings of the VI International Symposium on Turbulence, Heat and Mass Transfer 2009, pp. 567-570, ISBN 978-1-56700-262-1

Parabolic Trough Collectors (PTC)

One line of research in Concentrating Solar Power (CSP) is the development of a general model for a parabolic trough solar collector (PTC). A numerical heat transfer model based on Finite Volume Method (FVM) is carried out to determine the thermal performances of the heat collector element (HCE). An optical model for calculating the non-uniform solar flux distribution around the receiver is coupled to the thermal model. This model is based on Finite Volume Method and ray trace techniques and takes into account the finite size of the Sun. The general model is thoroughly validated with results from the literature. Numerical aerodynamic and heat transfer simulations based on Large Eddy Simulation of the flow are also being performed. By means of these detailed simulations, a quantitative assessment of velocity, pressure and temperature fields around the solar collector and its receiver is provided. Aerodynamic coefficients around the PTC for different wind speeds and pitch angles are calculated and validated with experimental measurements. Instantaneous velocity field is also studied and compared to aerodynamic coefficients for different pitch angles and wind speeds. The time-averaged flow is characterized by the formation of several recirculation regions around the solar collector and the receiver tube depending on the pitch angle and Reynolds number. Heat transfer coefficients around the heat collector element are also calculated for various pitch angle and wind speed and compared to the circular cylinder in a cross flow.

Fig. 1 -2: Validation of the drag (left) and lift (right) coefficients with wind tunnel test measurements from NREL

Fig. 3: Instantaneous velocities around the PTC for different pitch angles: θ= 0º(left). θ= 90º (middle) and θ=180º(right)  for ReW=3.6×105  (Reynolds based on the free-stream velocity and the PTC aperture)

Related Publications:

  • Hachicha, A. A., Rodríguez, I., Lehmkuhl, O., & Oliva, A. (2013). On the CFD&HT of the flow around a parabolic trough solar collector under real working conditions. SolarPACES 2013 Las Vegas (USA).
  • Hachicha, A.A., Rodríguez,I., & Oliva, A. (2012). Large-eddy simulations of fluid flow and heat transfer around a parabolic trough solar collector. Eurosun 2012 Rijeka (Croatia).
  • Hachicha, A.A., Rodríguez, I., Capdevila, R., & Oliva, A. (2011). Numerical simulation of a parabolic trough solar collector considering the concentrated energy flux distribution. 30th ISES Biennial Solar World Congress 2011, SWC 2011 Kassel (Germany), (5)3976-3987.