Assessment of a parabolic trough solar thermal concentrator under two-phase flow conditions

Abstract

In the present work, a mathematical model is developed to describe the heat, mass, and momentum transfer of a biphasic flow during its trajectory in the absorber tube of a parabolic trough solar concentrator (PTSC) for thermal processes in a transitory simulation, showing the evolution of the parameters in a dynamic system. The working fluid is water. The numerical solution of the model is implemented in C++ code. The model is validated with the results obtained from the DISS Project experiment. The results of the numerical solution have a maximum variation in the fluid temperature profile of 6.45 % and a maximum difference of 2.02 % in the outlet pressure of the fluid with respect to the experimental results. The case study consists of the analysis of a PTSC under different radiation conditions from two different cities in Mexico, Piedras Negras and Mexico City, on an average spring day. The results obtained allow us to analyze the behavior of the fluid temperature, the quality of the steam, and pressure drop through the absorber tube and time; under the conditions studied, the concentrator reached an efficiency of 52 %. It is observed that the model is sensitive to changes in climate.

Keywords

• Parabolic trough solar thermal concentrator
• Dynamic mathematical model
• Biphasic flow
• Heat transfer
• Thermal-solar