Abstract

VALENZUELA, Loreto; SAYNES, Jacobo  and  MOYA, Sara L.. Thermo-Hydraulic Analysis of Parabolic trough Collectors for Direct Steam Generation with Relap5. Tecnol. cienc. agua [online]. 2016, vol.7, n.3, pp.75-91. ISSN 2007-2422.

This paper presents a numerical thermo-hydraulic study of a standard row of parabolic-trough solar collector (PTC) for direct steam generation (GDV) working in the configuration oncethrough. The research was carried out with the simulator RELAP5/ MOD3. The considered PTC row has 10 units with a total length of 1000 m. The study of the row includes a performance analysis of the system under nominal conditions (70 bar and 723 K), and a sensitivity analysis to functioning variables and design parameters, such as: feed water temperature; perimeter distribution of the concentrated solar radiation in the wall of the absorber tube; and inner diameter and material of the absorber tube. It was found direct relation between the increase of the inlet temperature and the shift of the evaporation and superheating regions; this shift is 22m for the different temperature considered, remaining constant the length of the evaporation region, because neither the feed water flow nor the direct solar radiation were modified for this type of analysis. The perimeter profile of the concentrated solar radiation on the absorber tube seriously affects the convective heat transfer coefficients as well as the transition position in the preheating/evaporation and evaporation/superheating, especially for the second one with a difference of 18 m. With regard to the absorber tube inner diameter it was determined that the number of flux patterns is smaller when the inner diameter is bigger, regardless to the wall thickness or tube material. The material of the absorber tube, stainless steel 316Ti and ferritic steel A355 P22, affects mainly the flow transient behavior and the maximum differences in temperature in the transversal section of the absorber tube wall, being these differences higher when the absorber is made of stainless steel.

Keywords : Parabolic-Trough Collectors; Direct Steam Generation; Thermo-Hydraulic Model.

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