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Cyclic dehydrogenation-rehydrogenation (D-R) experiments are performed on thin oxide passivated contact (TOPCon) p-type poly-Si/SiOx stack to investigate the role of hydrogen atoms for crystalline silicon solar cell. The dehydrogenation steps are performed by thermal annealing at 450 °C for 1h under vacuum condition, and the rehydrogenation steps by hydrogen plasma treatment (HPT) at 300 °C for 1min. The ultrathin SiOx layer of 0.8±0.1 nm is realized by atomic layer deposition (ALD) technique allowing a precise control at atomic scale. The effective lifetime is enhanced to 1.4 ms by the HPT. The D-R method underlines the contribution of H atoms to the c-Si surface passivation that diffuses into the SiOx/c-Si interface. Besides, the lifetime recovery is well described by a stretched exponential function that indicates the dispersive nature of the p-type poly-Si/SiOx stack. [ABSTRACT FROM AUTHOR]

A transient three dimensional numerical model of the heat transfer and fluid flow of a windowed fluidized bed reactor for solar thermochemical conversions is formulated and solved using discrete element method coupled to computational fluid dynamics. Radiation transfer equation is solved by discrete ordinate radiation model and the particle collision dynamics is solved by spring-dashpot model based on soft-sphere method. The instantaneous granular flow behavior of the irradiated bed is presented along with the incident radiation and particle size distribution. The results indicate that as time progresses the average velocity of the particle increases due to high temperature and bed expansion effect. [ABSTRACT FROM AUTHOR]

The first performance test of a novel windowed solar fluidized bed reactor was carried out for a two-step water splitting cycle with ceria particles by using a 30-kWth sun-simulator. O2 and H2 were successfully produced by the reactor system. During the thermal reduction step of the two-step water splitting, a fluidized bed of ceria particles was created by passing N2 gas through the perforated bottom plate of the reactor, and about 30 kWth of high flux visible light from 19 xenon-arc lamps of the sun-simulator was directed inside the reactor through a quartz window to directly irradiate the top of the fluidized bed. The central bed temperature reached the temperature of 1400 to 1500°C in the thermal reduction step. The subsequent water decomposition or hydrolysis step was performed at the central bed temperature of 800 - 900°C. About 6 - 12 Ndm³ of hydrogen was produced by one cycle. [ABSTRACT FROM AUTHOR]

In this research, heat transfer and hydrodynamics of a solar thermochemical fluidized bed reactor filled with ceria particles have been studied numerically and experimentally for beam-down solar concentrating system. A CFDDEM model has been developed, in which the contact forces between the particles have been calculated by the springdashpot model, based on the soft-sphere method. An experimental visualization of particles circulation pattern and mixing of two-tower fluidized bed system has been presented. Simulation results have been compared with experimental data to validate the CFD-DEM model. Results indicate that the model can predict the particle-fluid flow of the two-tower fluidized bed reactor. Using this model, the key operating parameters can be optimized. [ABSTRACT FROM AUTHOR]

A window-type, solar fluidized bed receiver with quartz sand particles was tested by a 100-kWth novel beamdown solar concentrating system at Miyazaki, Japan. A compound parabolic concentrator (CPC) was placed above the quartz window of the receiver to increase the concentration of the solar fluxes from the beam-down solar concentrating system. The solar tests were performed in the middle of December, 2015. The central bed temperature of the receiver was reached around 960-1100° C. It was found that only 20 Ndm3/min of air flow rate was enough to create the uniform fluidization of the particles at the given temperature range. It was predicted that if the central bed temperature could have been higher than 1100°C if solar receiver test had conducted in other seasons than winter. The next solar campaign of the receiver test will be carried out in October, 2016. [ABSTRACT FROM AUTHOR]

This paper presents a numerical analysis of unconstrained melting of high temperature(>1000K) phase change material (PCM) inside a cylindrical container. Sodium chloride and Silicon carbide have been used as phase change material and shell of the capsule respectively. The control volume discretization approach has been used to solve the conservation equations of mass, momentum and energy. The enthalpy-porosity method has been used to track the solid-liquid interface of the PCM during melting process. Transient numerical simulations have been performed in order to study the influence of radius of the capsule and the Stefan number on the heat transfer rate. The simulation results show that the counter-clockwise Buoyancy driven convection over the top part of the solid PCM enhances the melting rate quite faster than the bottom part. [ABSTRACT FROM AUTHOR]

A novel concept of particles fluidized bed receiver/reactor with a beam-down solar concentrating optics was performed using a 30-kWth window type receiver by a big sun-simulator. A fluidized bed of quartz sand particles was created by passing air from the bottom distributor of the receiver, and about 30 kWth of high flux visible light from 19 xenon-arc lamps of the sun-simulator was directly irradiated on the top of the fluidized bed in the receiver through a quartz window. The particle bed temperature at the center position of the fluidized bed went up to a temperature range from 1050 to 1200?C by the visible light irradiation with the average heat flux of about 950 kW/m2, depending on the air flow rate. The output air temperature from the receiver reached 1000 - 1060?C. [ABSTRACT FROM AUTHOR]