A New Thermal-Solar Field Configuration: The Rotatory Fresnel Collector or Sundial

Abstract

A new type of Fresnel array has been devised and constructed as an answer to the need to reduce the investment costs of solar thermal collectors, without jeopardizing their efficiency in capturing solar radiation at high temperatures. The array of mirror bands is fixed onto a horizontal platform, which rotates around a virtual vertical axis, so that the sun is in the extrapolated vertical plane of symmetry of the array. The receptor central line is also placed in said plane, and it is physically made of at least one tube at each side of the plane. The geometrical relation between the mirrors and the receptor is therefore fixed. The platform rotates with the same speed as that of the sunlight’s azimuthal component. On the contrary, the angle of incidence of the sunlight on the mirrors changes as the sun rises and declines in its daily apparent motion, but this effect does not disturb the radiation concentration kinematics, although it induces a shift along the receptor. This is a new configuration based on the use of simple and cheap flat mirrors to obtain circular cylindrical mirrors. These mirrors are made of originally flat mirrors that are bent by applying an inexpensive and simple bending technique patented by our research group. The radius of curvature of each mirror is tuned to the distance from the mirror to the receiver central line. The integration of different scientific domains (such as structural analysis) and elementary technologies (such as 3D printing) in this innovative solar radiation concentrator and receiver can lead to a large reduction in costs. Nevertheless, the first experimental campaign has shown additional problems in the receiver configuration, which should be addressed in a next stage of research. This paper explains the methodology used and procedures in the development of the first prototype of the Sundial.

Scale-Up Considerations of the Sundial Rotating Fresnel Solar Collector

“…The objetive of the concept is to provide heat and cooling for industrial processes. Previous papers have provided detailed information concerning the design of the pilot collector [3], [4], its optical design and optimization [5], receiver performance [6], [7] and the performance of the collector when integrated with the ASTEP concept. The steady state modelling and results of the whole system were presented in [8], [9] and the dynamic behavior of the Sundial in was presented in [10], focusing on the effects of the thermal inertia of the system in [11].…”

The development of Fresnel lens concentrators for solar water heaters: a case study in tropical climates

“…The concept of light concentration consists of two methods, namely refraction and reflection. Method of concentration of solar thermal to produce hightemperature vapour (superheated) in solar power generation systems [7].…”

Integración de desarrollos en un prototipo termosolar, diseño de los sistemas de control, montaje general y detallado del prototipo, verificación y puesta en marcha = Integration of developments in a solar thermal prototype, control systems design, general assembly, verification and start-up procedure

“…Energies, [76]. También dentro del campo de conocimiento en el que se encuadra esta tesis se ha contribuido en el desarrollo obtención de varias patentes y modelos de utilidad:…”