Análisis térmico y comparativa de una planta conceptual de generación directa de vapor empleando canal parabólico y reflectores Fresnel optimizados

Abstract

Concentrating solar power systems provide a promising option for generating energy from the Sun using thermodynamic cycles. The most commonly used solar power systems are parabolic trough collectors, which use thermal oils as the working fluid. However, the direct steam generation concept provides an alternative approach that generates superheated steam directly in the solar field without using thermal oil. Additionally, one can implement linear Fresnel reflectors instead of parabolic trough collectors. While some analyses of direct steam generation in both concentration geometries exist, there need to be more impartial comparisons of the operating conditions, specifically in Mexico. Therefore, we carried out an unbiased evaluation of several solar fields operating under identical conditions to determine the best option. The analysis considers two 10 MW power blocks employing a Rankine cycle with two and three steam extractions. Sixteen solar fields capable of delivering superheated steam at 400◦C and 100 bar, with the mass flow restrictions in the absorbers taken into account, are analyzed. The comparison accounts for the effective concentration area, the nominal pressure at the inlet of each loop, the energy and exergy efficiency, and the hypothetical thermal storage size. Our findings suggest using parabolic trough collector solar fields with ten loops for superior overall performance in both power blocks. However, if pressure reduction is the primary concern, we can use three linear Fresnel reflector loops. For compact solar fields, we recommend using 2-loop of linear Fresnel reflector fields to minimize land use. Furthermore, we suggest using ten parabolic trough collectors loops to prioritize thermal energy storage and enable yearround solar plant operation, even though eight parabolic trough collectors loops would maximize thermal energy storage if that is the sole consideration. The analysis indicates that, under specific criteria, using Fresnel reflectors is advantageous compared to parabolic troughs, thereby providing an opportunity for further studies in this area and a foundation for studies of these technologies for Mexican operating conditions.