Heat Transfer and Thermal Insulation

Bai, Yong; Bai, Qiang

doi:10.1016/b978-1-85617-689-7.10014-7

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…• Heat transfer fluid piping. Solar thermal power plants are very large due to the low intensity of the original solar radiation and this make it necessary to have very long pipes to connect all the systems [13]. The pressure drop across the circuits can reach very high values, which leads to very high pumping power values (which can eventually be higher than the electrical power of the plant; a curious nonsense).…”

Section: Structure Of a Solar Thermal Power Plantmentioning

confidence: 99%

Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies

Nogueras¹

2020

EPE

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Radiation is a form of energy where the angular variable of the direction of its photons has a primary importance, particularly for radiation concentration processes, which are essential tools to reach high temperatures from radiation beams (as the solar ones) with moderate intensities. Solar radiation cannot be used directly to feed thermodynamic cycles, and optical concentration must be applied to that goal. In general, reflection from mirrors is preferred to refraction by lenses in this case, because they have less optical aberrations. Concentration conveys very high temperatures in the receiver. However, the higher the temperature, the lower the efficiency of the solar thermal apparatus. Besides that, economy also suffers quite a lot when going to very high concentration factors, which is one of the main burdens in the development of Solar Thermal Energy. A new configuration of solar radiation concentrator is presented. It includes a salient innovation in the way the mirrors are given the right curvature by mechanical forces. Those mirrors are originally flat and do not need any special thermal treatment for this purpose. The whole device concept has been guided by the principle of thermo-economic coherence, which requires similar efforts in all degrees of freedom that have strong influence in the performance and cost of the system. The paper shows the decision tree that has oriented the project, following the principle of equilibrium in efforts, which leads to a design window of moderate values in the main variables. The prototype of this new configuration has already been built, and the first stage of research is considered to be finished, because the prototype has shown excellent conditions to include selected (fitting) technologies at a very low cost.

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Section: Structure Of a Solar Thermal Power Plantmentioning

confidence: 99%

Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies

Nogueras¹

2020

EPE

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

2021

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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.

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Heat Transfer and Thermal Insulation

Cited by 2 publications

References 2 publications

Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies

Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies

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

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