ASTEP project creates an innovative Solar Heat to Industrial Processes concept that will be tested at two industrial sites.
The first one is a factory of ArcelorMittal Tubular Products (AMTP) located at a latitude of 47.1 N (Iasi, Romania). The second one is the dairy company Mandrekas, located at a latitude of 37.93 N (Corinth, Greece).
The objective of the preliminary design is to propose a configuration that fulfils the thermal requirements of the industry.
In the case of the AMTP factory, the requirement of the industry is a heating demand up to 230 ºC for preheating the tubes before applying a coating. This requirement at such a high latitude is one of the challenges of the ASTEP project. Other requirement to be accomplished is the production of thermal energy at daily and yearly basis (up to 135 kWh per day and 25 MWh yearly).
The SunDial for this case-study is a rotary Linear Fresnel collector with a transversal mirror field arrangement. With this arrangement, the sun is in the transversal plane to the receiver, and there are a two-axes solar tracking system: not only the platform rotates (to follow the solar azimuth) but also the mirrors (to follow the solar height).
Two types of receivers and two solar fields configuration have been considered. The types of receivers are single and multi-tube ones, while the mirrors field configurations are single-field and two semi-fields.
The system design specification implies the selection of a set of geometric parameters to define:
- the receiver,
- the primary reflectors and
- the solar field configuration.
Having in mind that the ultimate objective is to accomplish an optimal design to cover the thermal requirements, it is necessary to make use of numerical models to characterize the performance of the different elements of the Sundial.
First, the models to estimate the thermal performance of both types of receivers have been developed. Likewise, a Monte Carlo ray tracing model has been developed to analyse the optical performance of the fields. Besides, other developed models aim to analyse the effect of the mirror dimensions on its optimal shape as well as to calculate the corresponding bending moment to focus the solar irradiation onto the receiver, which is a constraint of the design.
Finally, an analytic methodology followed by a numeric computation that integrates all the beforementioned models is used to optimise the design of the mirrors field, with the aim of achieving the requirements of the case-study.
The multiple proposed configurations are analysed following these steps and then compared. The configuration finally selected includes two semi-fields of mirrors and single-tube receiver design.
Authors: R Abbas (UPM), R Barbero, MJ Montes, M Muñoz, A Rovira (UNED).