Numerical Simulation and Design of Multi-Tower Concentrated Solar Power Fields

Abstract

In power tower systems, the heliostat field is one of the essential subsystems in the plant due to its significant contribution to the plant's overall power losses and total plant investment cost. The design and optimization of the heliostat field is hence an active area of research, with new field improvement processes and configurations being actively investigated. In this paper, a different configuration of a multi-tower field is explored. This involves adding an auxiliary tower to the field of a conventional power tower Concentrated Solar Power (CSP) system. The choice of the position of the auxiliary tower was based on the region in the field which has the least effective reflecting heliostats. The multi-tower configuration was initially applied to a 50 MWth conventional field in the case study region of Nigeria. The results from an optimized field show a marked increase in the annual thermal energy output and mean annual efficiency of the field. The biggest improvement in the optical efficiency loss factors be seen from the cosine, which records an improvement of 6.63%. Due to the size of the field, a minimal increment of 3020 MWht in the Levelized Cost of Heat (LCOH) was, however, recorded. In much larger fields, though, a higher number of weaker heliostats were witnessed in the field. The auxiliary tower in the field provides an alternate aim point for the weaker heliostat, thereby considerably cutting down on some optical losses, which in turn gives rise to higher energy output. At 400 MWth, the multi-tower field configuration provides a lower LCOH than the single conventional power tower field.

An optimisation study of a solar tower receiver: the influence of geometry and material, heat flux, and heat transfer fluid on thermal and mechanical performance

“…The radiation generated by the heliostat does not hit the receiver completely since the environment consumes a measure of energy. The collection failure, or spillage, is expressed in reflected energy from the mirrors aiming the receiver, which does not land on the absorption region [1]; reducing the receiver size significantly impacts the spillage loss.…”

“…The radiation generated by the heliostat does not hit the receiver completely since the environment consumes a measure of energy. The collection failure, or spillage, is expressed in reflected energy from the mirrors aiming the receiver, which does not land on the absorption region [ 1 ]; reducing the receiver size significantly impacts the spillage loss. However, the advantages of small receiver sizes are highly valued, due to their better performance with a smaller heliostat and higher peak flux limit, reduced receiver costs, and improved thermal efficiency by reducing thermal losses such as convection and radiation [ 2 ].…”

Optimum Height and Tilt Angle of the Solar Receiver for a 30 kWe Solar Tower Power Plant for the Electricity Production in the Sahelian Zone

“…The solar field represents the key subsystem of the STPP because it contributes around 50% [9] of the total cost of the plant and causes 40% [10] of the overall energy losses. So the performance of a solar STPP depends strongly on the solar field efficiency [11].…”

Design optimization of a solar tower power plant heliostat field by considering different heliostat shapes

“…12 Alternative optimizations were based on the use of Multitower heliostat field with different receivers during the day. [13][14][15][16] Different parameters can lead to an increased optical field efficiency such as the choice of the appropriate position of the auxiliary tower which plays an alternate focused point to overcome the losses due to the weaker heliostat. This can be achieved based on group decision-making approach, that allows the orientation of each heliostat according to the best receiver that provides the highest possible instantaneous field efficiency.…”

“…Other studies focused on the optimization of the receiver size and fluid flow layout 12 . Alternative optimizations were based on the use of Multi‐tower heliostat field with different receivers during the day 13‐16 . Different parameters can lead to an increased optical field efficiency such as the choice of the appropriate position of the auxiliary tower which plays an alternate focused point to overcome the losses due to the weaker heliostat.…”