Some Alternative Technologies for Solar Thermal Power Generation

Abstract

Two advanced optical systems and a highly efficient thermal cycle suitable for beam-down power tower with thermal storage are presented. (1) To increase field efficiency, the “cross beam” heliostat array concept is proposed. Using continuum optical model, the characteristics of the cross beam concept and its economy were investigated. (2) To protect the central reflector (CR) against wind force, a “multi-ring CR” concept is proposed. The concentration performance of multi-ring CRs is calculated using the ray-tracing method. It shows no worse results than the case with a single hyperboloid mirror. (3) The potential of a closed gas turbine cycle with supercritical carbon dioxide as a working fluid was investigated. An optimal cycle configuration involves a regenerative cycle with pre-cooling and inter-cooling cycles, in which theoretically achievable cycle thermal efficiency is 47% at the turbine inlet temperature of 800 K and turbine inlet pressure of 20 MPa. Detailed thermal design of a critical component, regenerative heat exchanger (RHX) is carried out using a newly developed printed heat exchanger (PCHE). It proved to be a feasible design.

Supercritical CO2 Brayton cycles for solar-thermal energy

“…Echogen has considered sCO 2 cycles for waste heat recovery, utilizing smaller power systems [34] and views sCO 2 as a valid competitor to steam technology [35]. While some work has been done pertaining specifically to solar applications, the literature for sCO 2 is introductory by comparison [11,36]. The Southwest Research Institute is also active in enabling sCO 2 for solar energy and is pursuing turbo--expander and heat exchanger development for this purpose [37].…”

Thermochemical Cycles for High-Temperature Solar Hydrogen Production

“…The reflection and concentration of direct insolation can be achieved by sun-tracking mirrors called collectors or heliostats. Some modern solar-concentrating systems have maximum concentration factors in the 1500−5000 range and can provide high-temperature solar thermal heat (up to a few hundred kilowatts, and even tens of megawatts in the sunbelt regions). − The concentrated solar radiation is focused upon a solar receiver, where maximum temperatures can exceed 1500 °C, depending upon the configuration of the solar concentrating system. The receiver efficiency depends on a concentration factor.…”

“…The first step of this process is the reflection and concentration of direct insolation using collectors/heliostats. Large-scale solar concentrating systems have been developed for about three decades. − Primarily four types of solar concentrating systems have been developedparabolic trough, power tower, dish, and double-concentration systemswhich are continually increasing in their capability to convert high-temperature heat from concentrated solar radiation into electricity, process heat, and chemical fuels. These four systems are shown schematically in Figure .…”

Gas Turbine Power Augmentation: Parametric Study Relating to Fog Droplet Size and Its Influence on Evaporative Efficiency

“…Recent theoretical and experimental work on wet compression and interstage injection may be found in Refs. [18][19][20][21][22][23][24]. Brun et al have covered several practical considerations and important evaluations that should be considered prior to the use of wet compression [25].…”