Modeling and analysis of a relocatable solar power tower for pressurized water heating and storage providing low to medium temperature industrial process heat

Abstract

Solar power tower systems have been extensively investigated for mega-scale electricity generation, but very little is seen in applications that provide industrial process heat. The use of solar power tower systems for low to medium-temperature industrial process heat (less than 400˚C) is particularly not well addressed. In this study, an algorithm is developed to model, evaluate, and optimize the performance of a novel relocatable solar power tower system that can provide low to medium-temperature process heat for use in applications such as in oil fracking, district heating, and the mining industry. A 1.3 MWth solar power tower based industrial process heat plant is considered to supply heat at a reference location, in Tucson, Arizona. The study mainly focuses on modeling and optimizing a biomimetic heliostat field of small-size removable heliostats (4 m2) and a 40 m-high steel truss tower, based on an optimized light-weight external receiver that utilizes pressurized hot water as the heat transfer fluid for steam production in a temperature range of 120 – 220˚C, which is the dominant temperature requirement in process heating. The developed model simultaneously couples and optimizes the heat transfer and optical performance of the receiver and heliostat field at design conditions, while the annual transient thermal and optical losses are evaluated as well. The geometry of the external receiver, the biomimetic heliostat field shape factors, and the tower height were evaluated parametrically and optimized to maximize the energy yield (i.e., highest receiver’s efficiency and lowest land use). The approach of modeling and optimization was validated through the analysis of two reference solar thermal power plants with molten salt (i.e., SOLARTWO and GEMASOLAR plants), showing a very satisfactory agreement with the design parameters in the literature. A comparison with a radial staggered heliostat field modeled using SolarPILOT software was also conducted.