A Wind Engineering Analysis of Parabolic Trough Concentrating Solar Power

This thesis aims at improving the understanding of the effects of the wind on parabolic trough Concentrating Solar Power technology. Parabolic trough power plants are often located in areas that are subjected to high wind speeds, as an open terrain without any obstructions is beneficial for the plant performance. The wind impacts both the structural requirements and the performance of the plant. The aerodynamic loads from the wind impose strong requirements on the support structure of the reflectors, and they also impact the tracking accuracy. On a thermal level the airflow around the glass envelope of the receiver tube cools its outer surface through forced convection, thereby contributing to the total heat loss of the system. The influence of the shape and design of the trough is studied with the aim to minimise wind loads and thermal losses and, thus, contribute to making parabolic trough technology more efficient and hence reduce the cost of the generated electricity. Starting with an investigation on the level of a single row of collectors, the influence of different trough depths on the wind effects — the aerodynamic loads, as well as the thermal effects — is analysed via numerical simulations that are validated against experimental data from wind tunnel tests. While a deeper trough geometry leads to higher forces than a shallow one, it also significantly reduces the wind speed around the receiver and hence the thermal loss on its outer surface. Based on these results alterations to the standard trough design of a continuous parabolic shape are undertaken, analysed in numerical simulations, and validated in wind tunnel experiments. A staggered reflector layout with different focal lengths in different sections of the trough is found to be able to reduce the wind loads by up to 24%,while some designs also retain the sheltering effect on the receiver. Various numerical simulation approaches for an adequate representation of the wind effects on individual rows of collectors, as well as in a solar field are investigated and compared. For the simulation of a solar field, time-averaged simulations of a large domain with several collector rows are compared with a transient simulation with stream-wise periodic boundary conditions. At the level of an individual collector row, the performance and results of a transient scale resolving simulation are compared with those of a simulation using synthetic turbulence generation at the inlet boundary