sufficient efficiency, cavity-type receivers made up of ceramic materials have been used, whereby the absorption of
the receiver is increased by focusing concentrated solar radiation through a small aperture e.g. [4].
In the past few decades, significant progress has been achieved in the development of optical systems for large
scale solar concentration and capable to reach more than 2000 K, which are required for the efficient two step
thermochemical cycles [5]. The first step is the dissociation of metal oxide to metal or lower valance metal oxide by
endothermic reaction using solar energy. The second step is the hydrolysis of metal to produce hydrogen and the
corresponding metal oxide by non-solar exothermic reaction. One of the most favorable metal oxide pairs for two
step thermochemical cycle is apparently ZnO/Zn. Thermal dissociation of this redox pair has been extensively
studied e.g. [6] . A three-step thermochemical cycles have also been investigated for hydrogen production such as
Mn2O3/MnO redox pairs e.g. [7]. Recently, thermal reduction of non-volatile metal oxides by directly exposing the
reactant to high radiation fluxes have been investigated by our group using lab-scale thermochemical reactor [8, 9],
and the instantaneous oxygen concentration at the outlet is measured using ZrO2-cell oxygen analyzer. The main
objective of this investigation is to develop a transient 3D numerical model to study the thermal performance of the
reactor since the chemical reactions involved in the thermochemical cycles as described in aforementioned processes
depend on the heat transfer process involved in the reactant and its atmosphere.
sufficient efficiency, cavity-type receivers made up of ceramic materials have been used, whereby the absorption of
the receiver is increased by focusing concentrated solar radiation through a small aperture e.g. [4].
In the past few decades, significant progress has been achieved in the development of optical systems for large
scale solar concentration and capable to reach more than 2000 K, which are required for the efficient two step
thermochemical cycles [5]. The first step is the dissociation of metal oxide to metal or lower valance metal oxide by
endothermic reaction using solar energy. The second step is the hydrolysis of metal to produce hydrogen and the
corresponding metal oxide by non-solar exothermic reaction. One of the most favorable metal oxide pairs for two
step thermochemical cycle is apparently ZnO/Zn. Thermal dissociation of this redox pair has been extensively
studied e.g. [6] . A three-step thermochemical cycles have also been investigated for hydrogen production such as
Mn2O3/MnO redox pairs e.g. [7]. Recently, thermal reduction of non-volatile metal oxides by directly exposing the
reactant to high radiation fluxes have been investigated by our group using lab-scale thermochemical reactor [8, 9],
and the instantaneous oxygen concentration at the outlet is measured using ZrO2-cell oxygen analyzer. The main
objective of this investigation is to develop a transient 3D numerical model to study the thermal performance of the
reactor since the chemical reactions involved in the thermochemical cycles as described in aforementioned processes
depend on the heat transfer process involved in the reactant and its atmosphere.
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