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Correction for ‘Mesoporous thin film WO3 photoanode for photoelectrochemical water splitting: a sol–gel dip coating approach’ by Samantha Hilliard et al., Sustainable Energy Fuels, 2017, 1, 145–153.

Today, oil and gas fields gradually become mature with a high amount of water being produced (water cut (WC)), favoring conditions for gas hydrate formation up to the blockage of pipelines. The pressure drop is an important parameter which is closely related to the multiphase flow characteristics, risk of plugging and security of flowlines. This study developed a model based on flowloop experiments to predict the relative pressure drop in pipelines once hydrate is formed in high water cutsystems in the absence and presence of AA-LDHI and/or salt. In this model, the relative pressure drop during flow is a function of hydrate volume and hydrate agglomerate structure, represented by the volume fraction factor (Kv). This parameter is adjusted for each experiment between 1.00 and 2.74. The structure of the hydrate agglomerates can be predicted from the measured relative pressure drop as well as their impact on the flow, especially in case of a homogeneous suspension of hydrates in the flow.

Abstract The quenching process has become an important thermal management study to intensify the safety margin for the integrity of the reactor vessel under the core meltdown condition. The boiling heat transfer mechanism in the channel is one aspect that needs further examination. The present study aimed to investigate the effect of the differences in channel gap size to counter-current flow limitation (CCFL) and critical heat flux (CHF) during transient cooling in atmospheric pressure and quenching using two vertical plates with 1 mm, 2 mm, and 3 mm gap sizes and heated length of 1100 mm. The initial temperature of the plate was set at 600 °C. Cooling water mass flow rate and sib-cooled temperature were set at about 0.089 kg/s and 90 °C, respectively. Calculations were performed to obtain the CHF value through the boiling curve using transient temperature data. Non-dimensional correlations from other research study was used in this research. The influence of gap sizes on CCFL and CHF resulted in an increased value of CHF relative to gap size; additionally, the CHF for gap sizes of 2 mm and 3 mm increased about 34.4% and 140.5%, respectively, compared to the CHF for the 1 mm gap size. In this research, a curve map of the relationship between non-dimensional CHF and non-dimensional mass flux of water flowing downward shows that the correlation of this experimental study has a gradient number of about 0.22 similar to Mishima and Nishihara correlation. The results confirmed the existence of CCFL in the vertical narrow rectangular channels due to changes in gap sizes that contribute to changes in CHF. Rewetting time also became longer with increasing gap sizes.

Biomethane is produced by removing undesirable components such as water vapor, carbon dioxide and other pollutants in a biogas upgrading process. Frosting the water vapor contained in the biogas is one of the dehydration processes used in a biogas upgrading process. In order to simulate a frost layer on a cold plate, many models have been developed. These models are valid for a limited temperature range. In this study, heat and mass transfer equations were used in a numerical approach to model the frost growth and its densification on the external side of a fin-and-tube heat exchanger. The model used in this study is valid for low temperatures from 0[Formula: see text]C to [Formula: see text]C and lower. The evaporation process of temperature glide refrigerants is also modeled from [Formula: see text]C to [Formula: see text]C. The results show a decreased heat transfer rate during frost mass growth on fins and rows. During its growth, frost layer thermal conductivity is relatively low leading to decrease the heat exchanger performance. On the other hand, frost layer thickness increases the external surface blockage, leading to higher pressure drop on the external side. This model has been validated by comparing numerical and experimental results for the biogas outlet temperature.

AbstractRecent breakthroughs in Cu(In,Ga)Se2 (CIGS) thin film solar cell energy conversion efficiency are related to the application of a potassium fluoride post‐deposition treatment (KF‐PDT) to the completed absorber. Using X‐ray photoelectron spectroscopy and Raman scattering, we compare CIGS layers prior and after the KF‐PDT in the case of a deterioration and an improvement of the solar cells photovoltaic performance. The purpose is to study and model the modification of the surface in both cases and address some of the required characteristics of the absorber, grown on soda lime glass by 3‐stage process, in order to take advantage of the treatment. We show that, in both cases, KF‐PDT induces the formation of GaF3, which is removed during the subsequent chemical bath deposition of CdS, explaining the Ga depleted absorber surface, already reported in literature. However, the presence or not of an ordered defect compound (ODC), correlated with the third stage duration during the CIGS growth, is shown to be crucial in the modifications of the surface induced by the treatment. When an ODC is present prior the treatment, KF‐PDT leads to the formation of a surface layer of In2Se3 containing K, and the photovoltaic performance of completed solar cells are improved. When no ODC is present prior KF‐PDT, no trace of K is found at the absorber surface after the treatment, copper (Cu) segregates into detrimental CuxSe phases, high amount of elemental Se is formed, and the photovoltaic performance are lowered. The role of the ODC during the KF‐PDT is finally discussed.

Abstract The drying of sewage sludge is a current environmental problem, not sufficiently described in the literature. Hence, the aim of this work is a numerical study of heat and mass transfers during solar drying of residual sludge. This sludge is assimilated to a porous medium and exposed to a forced convection laminar flow within a horizontal channel. The transfers in the channel and the porous medium are respectively described by the classic equations of forced convection and the Darcy-Brinkman-Forchheimer model. The implicit finite difference method is used to discretize the governing differential equation system. The algebraic systems obtained are solved using the Gauss, Thomas and Gauss-Seidel algorithms. To determine the drying rate, we associate a drying kinetics model. We particularly studied the effects of solar radiation intensity on the space-time evolution of temperature, velocity and mass fraction at the porous medium-fluid interface. Moreover, the evolutions of the Nusselt numbers are represented to characterize the transfers at the sludge surface. This work is completed by a drying kinetics study. Indeed, we represent the effect of solar radiation on the space-time evolution of the drying rate.

Abstract The waste management of radioactive evaporator concentrates (EC) in deep geological repositories requires safe immobilization in a solid matrix, such as cement composites. Radiolysis occurs inside the hydrated cement paste due to irradiation of either free or bonded water. As a result, the generation of hydrogen and the consequent pressure build-up within the material may pose safety risks within the geological repository. Three kinds of cement pastes sealed in steel containers were irradiated by gamma source 60Co to achieve absorbed dose of 1.75 MGy simulating the conditions inside a repository. Specific binder matrix suitable for cement composites immobilizing EC marked as “NP” was studied, as well as the actual simulated immobilized waste (model concentrate) in the binder marked as “NP_C” and a reference paste “PC”. Results showed an increase in pressure of generated gas from the irradiated samples up to 100 kPa. After 120 days of irradiation the reference paste reached steady state, while NP and NP_C continued in the rising trend. However, the absolute values of NP_C were lower than the values of the reference paste, probably due to the presence of dissolved salts in the model concentrates, especially nitrates. The maximum value reached does not present safety risks within the repository, moreover the presence of certain salts in the concentrate has a positive effect on the decrease of the rate and the final values of the pressure build-up.