Experimental design of a fluidized bed solar receiver with direct absorption of concentrated solar radiation

2008 ◽  
Author(s):  
Arezki Bounaceur ◽  
Jean Jacques Bezian ◽  
Alain de Ryck ◽  
Jean Claude Poussin ◽  
Gabriel Olalde
Keyword(s):  
Experimental Design ◽  
Solar Radiation ◽  
Fluidized Bed ◽  
Direct Absorption ◽  
Concentrated Solar Radiation ◽  
Solar Receiver

Heat Transfer Model of a 50 kW Solar Receiver–Reactor for Thermochemical Redox Cycling Using Cerium Dioxide

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
S. Zoller ◽  
E. Koepf ◽  
P. Roos ◽  
A. Steinfeld
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Solar Radiation ◽  
Cerium Dioxide ◽  
Input Power ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Solar Reactor ◽  
Concentrated Solar Radiation ◽  
Solar Receiver

This work reports on the development of a transient heat transfer model of a solar receiver–reactor designed for thermochemical redox cycling by temperature and pressure swing of pure cerium dioxide in the form of a reticulated porous ceramic (RPC). In the first, endothermal step, the cerium dioxide RPC is directly heated with concentrated solar radiation to 1500 °C while under vacuum pressure of less than 10 mbar, thereby releasing oxygen from its crystal lattice. In the subsequent, exothermic step, the reactor is repressurized with carbon dioxide as it cools, and at temperatures below 1000 °C, the partially reduced cerium dioxide is re-oxidized with a flow of carbon dioxide. To analyze the performance of the solar reactor and to gain insight into improved design and operational conditions, a transient heat transfer model of the solar reactor for a solar radiative input power of 50 kW during the reduction step was developed and implemented in ANSYS cfx. The numerical model couples the incoming concentrated solar radiation using Monte Carlo ray tracing, incorporates the reduction chemistry by assuming thermodynamic equilibrium, and accounts for internal radiation heat transfer inside the porous ceria by applying effective heat transfer properties. The model was experimentally validated using data acquired in a high-flux solar simulator (HFSS), where temperature evolution and oxygen production results from model and experiment agreed well. The numerical results indicate the prominent influence of solar radiative input power, where increasing it substantially reduces reduction time of the cerium dioxide structure. Consequently, the model predicts a solar-to-fuel energy conversion efficiency of >6% at a solar radiative power input of 50 kW; efficiency >10% can be obtained provided the RPC macroporosity is substantially increased, and better volumetric absorption and uniform heating is achieved. Managing the ceria surface temperature during reduction to avoid sublimation is a critical design consideration for direct absorption solar receiver–reactors.

Numerical Investigation on Optimal Design of Solid Particle Solar Receiver

2007 ◽  
Author(s):  
Huajun Chen ◽  
Yitung Chen ◽  
Hsuan-Tsung Hsieh ◽  
Greg Kolb ◽  
Nathan Siegel
Keyword(s):  
Solar Radiation ◽  
Solid Particle ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Load Model ◽  
Concentrated Solar Radiation ◽  
Tracing Algorithm ◽  
Solar Receiver ◽  
And Storage

Solar thermo-chemical processes often require high temperatures that can be achieved by direct absorption of solar energy. The solid particle solar receiver can be used to heat ceramic particles that may serve as a heat transfer and storage medium or as a substrate on which chemical reaction may be performed directly. Using solid particles enclosed in a cavity to absorb concentrated solar radiation can provide efficient absorption of concentrated sunlight. In this work, different solid particle solar receiver designs have been investigated by using computation fluid dynamics (CFD) technique. The gas particle flow with the solid particle solar receiver was simulated by using two-way coupled Euler-Lagrange method. The direct illumination energy source that results from incident solar radiation was predicted by a solar load model using a solar ray tracing algorithm. The detailed information to guide the experiment, such as the particle and gas velocity, temperature, particle solid volume fraction, and cavity efficiency under different designs has been analyzed.

Experimental and Numerical Analyses of a Pressurized Air Receiver for Solar-Driven Gas Turbines

2010 ◽  
Author(s):  
Illias Hischier ◽  
Pascal Leumann ◽  
Aldo Steinfeld
Keyword(s):  
Power Generation ◽  
Monte Carlo ◽  
Steady State ◽  
Gas Turbines ◽  
Porous Ceramic ◽  
Operating Pressure ◽  
Radiative Fluxes ◽  
Monte Carlo Techniques ◽  
Concentrated Solar Radiation ◽  
Solar Receiver

A high-temperature pressurized air-based receiver for power generation via solar-driven gas turbines is experimentally and theoretically examined. It consists of an annular reticulate porous ceramic (RPC) foam concentric with an inner cylindrical cavity-receiver exposed to concentrated solar radiation. Absorbed heat is transferred by combined conduction, radiation, and convection to the pressurized air flowing across the RPC. The governing steady-state mass, momentum and energy conservation equations are formulated and solved numerically by coupled Finite Volume and Monte Carlo techniques. Validation is accomplished with experimental results using a 1 kW solar receiver prototype subjected to average solar radiative fluxes in the range 1870–4360 kW m−2. Experimentation was carried out with air and helium as working fluids, heated from ambient temperature up to 1335 K at an absolute operating pressure of 5 bars.

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