Experimental investigation of a liquid cooled high temperature proton exchange membrane (HT-PEM) fuel cell coupled to a sodium alanate tank

In high temperature proton exchange membrane (HT-PEM) fuel cells, waste heat at approximately 160 °C is produced, which can be used for thermal integration of solid state hydrogen storage systems. In the present study, an HT-PEM fuel cell stack (400 W) with direct liquid cooling is characterized and coupled to a separately characterized sodium alanate storage tank (300 g material). The coupled system is studied in steady state for 20 min operation and all relevant heat flows are determined. Even though heat losses at that specific power and temperature level cannot be completely avoided, it is demonstrated that the amount of heat transferred from the fuel cell stack to the cooling liquid circuit is sufficient to desorb the necessary amount of hydrogen from the storage tank. Furthermore, it is shown that the reaction rate of the sodium alanate at 160 °C and 1.7 bar is adequate to provide the hydrogen to the fuel cell stack. Based on these experimental investigations, a set of recommendations is given for the future design and layout of similar coupled systems.     

Optimization of hydrogen charging process parameters for an advanced complex hydride reactor concept

Complex hydrides are identified as promising hydrogen storage media with gravimetric capacities up to 10 wt.%. However, the high temperatures required for the initiation of their hydrogen charging process and their slow kinetics prevent their integration in many practical applications. This paper discusses the challenge of addressing these issues by combining this kind of materials with the appropriate metal hydrides. For this purpose, the complex hydride, 2LiNH₂–1.1MgH₂–0.1LiBH₄–3 wt.% ZrCoH₃ (CxH) and the metal hydride, LaNi_4.3Al_0.4Mn_0.3 (MeH) have been selected as reference materials. The studied configuration corresponds to a tubular reactor where the metal hydride and the complex hydride, separated by a gas permeable layer, are embedded respectively in the centre and the annular ring of the reactor. A 1-dimensional finite element model and a dimensionless number comparing the dominance of the kinetics and the heat transfer processes have been developed to optimize the charging process for different thicknesses and volumetric ratios of the studied materials. For the selected cases, the influence of the thermal properties of the complex hydride and the operating conditions on the charging process is assessed. A sensitivity study has shown that the thermal conductivity of the CxH is the most important parameter influencing the hydrogen storage rate if thick MeH and CxH beds are considered. In contrast, the hydrogen loading time is significantly improved by increasing the coolant temperature for small thicknesses of the two storage media. Thereafter, the gravimetric and volumetric capacities resulting from the scale up of the optimized configurations to store 1 kg of hydrogen are calculated and results are discussed taking into account the interdependence of the different studied parameters.     

Property prediction and consistency analysis by a reference series method

Data analysis and prediction of pure component properties of long‐chain substances is considered. The emphasis is on homologous series and properties for which insufficient data are available. A two‐stage procedure is recommended, whereby a linear (or nonlinear) quantitative structure–property relationship (QSPR) is fitted to a “reference” series, for which an adequate amount of precise data is available. This QSPR should represent correctly both the available data and the asymptotic behavior of the property. In the second stage a quantitative property‐property relationship (QPPR) is derived to represent the predicted property values of a “target” series in terms of the property values of the reference series. The procedure is applied for properties which are highly correlated with the number methylene groups in homologous series: and . It is shown that the method is very useful for consistency analysis of property data and enables a reliable prediction of and , and, thus, also of for long‐chain substances. © 2012 American Institute of Chemical Engineers AIChE J, 59: 420–428, 2013     

Analysis of knitted fabrics deformations non-uniformity

The article presents the tensile forces caused knitted fabrics’ deformations non-uniformity analysis. At first, the tensile behaviour was analysed by applying new method based on specific Y-shaped and stretching specimen. This shape of specimen allows to fulfil wearing conditions of apparel made of knitted fabrics. After this, the article analyses research conditions and knitted fabrics’ deformability physical characteristics and determines longitudinal, transverse and angular deformations. The deformations properties were evaluated using graphic and numerical methods. Investigations have shown that elastane fibres significantly influenced fabric deformability, dimensional changes and deformations’ non-uniformity. Experiments have also shown that Y-shaped specimen tensile test is a simple, universal and reliable method suitable to obtain quantitative information about textile materials deformability.     

Influence of solution composition on sprayed ZnO nanorods properties and formation process: Thermoanalytical study of the precursors

ZnO is an important inorganic material for numerous applications. Different physical and chemical methods have been applied to deposit ZnO. Spray pyrolysis method being simple, rapid and low-cost is amongst the many options and has been chosen for this study. Fabrication of ZnO nanorods crystals by chemical spray pyrolysis was performed using an acidic solution of ZnCl₂1 or a basic ammonia-containing solution of ZnCl₂2. All layers were studied using X-ray diffractometry and Scanning Electron Microscopy. The formation of ZnO nanorods from 2 appeared at 450?°C, whereas spraying acidic solution 1 yielded ZnO nanorods like morphology at 550?°C.Thermal decomposition of precursors for ZnO layers prepared by de-watering of acidic aqueous solution of ZnCl₂ with pH =?3 (1) and basic solution of ZnCl₂ and NH₄OH with pH =?10 (2) was monitored by simultaneous thermogravimetric and differential thermal analysis (TG/DTA) in air coupled online with evolved gas analyses by Fourier transformed infrared spectroscopy (FTIR).The precursor (1) is ZnCl₂ *nH₂O; the precursor (2) is a mixture of (NH₄)₃(ZnCl₄)Cl, Zn(NH₃)₂Cl₂, NH₄Cl(NH₃)₃ and Zn(OH)₂ phases. The thermal decomposition of (1) and (2) in the temperature range of 30–700?°C consists of two steps with total mass losses of 86.2% and 93.8%, respectively. The main evolved gases from (1) are H₂O and HCl, whereas the main evolved gases from (2) are H₂O, NO_x and NH₃. Degradation of (1) and (2) is completed by 670 and 620?°C, respectively. The final decomposition product of (1) and (2) at 700?°C is ZnO.This study shows that the use of basic solutions enables to decrease the temperature of ZnO formation and the deposition temperature of ZnO nanorods layers.     

CFH Loss in Human RPE Cells Leads to Inflammation and Complement System Dysregulation via the NF-κB Pathway

Age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, is a degenerative disease of the macula, where retinal pigment epithelium (RPE) cells are damaged in the early stages of the disease, and chronic inflammatory processes may be involved. Besides aging and lifestyle factors as drivers of AMD, a strong genetic association to AMD is found in genes of the complement system, with a single polymorphism in the complement factor H gene (CFH), accounting for the majority of AMD risk. However, the exact mechanism of CFH dysregulation confers such a great risk for AMD and its role in RPE cell homeostasis is unclear. To explore the role of endogenous CFH locally in RPE cells, we silenced CFH in human hTERT-RPE1 cells. We demonstrate that endogenously expressed CFH in RPE cells modulates inflammatory cytokine production and complement regulation, independent of external complement sources, or stressors. We show that loss of the factor H protein (FH) results in increased levels of inflammatory mediators (e.g., IL-6, IL-8, GM-CSF) and altered levels of complement proteins (e.g., C3, CFB upregulation, and C5 downregulation) that are known to play a role in AMD. Moreover, our results identify the NF-κB pathway as the major pathway involved in regulating these inflammatory and complement factors. Our findings suggest that in RPE cells, FH and the NF-κB pathway work in synergy to maintain inflammatory and complement balance, and in case either one of them is dysregulated, the RPE microenvironment changes towards a proinflammatory AMD-like phenotype.     

Distribution of thermal conductivities in the Groß Schönebeck (Germany) test site based on 3D inversion of deep borehole data

The main objective of the study was to develop and calibrate the thermal model of the Groß Schönebeck test site in Northeastern Germany, and to perform sensitivity analyses based on the availability of high-quality temperature data from deep wells. A 3D geological model of the area was constructed and then discretized into a finite element mesh that included 13 different lithologic units of variable thickness. Forward numerical calculations of the temperature field were performed based on measured and assumed data and properties. Finally, inverse modeling was used to improve parameter estimation and to obtain comprehensive statistic information. The results of the computations indicate some spatial thermal conductivity inhomogeneities in the different geologic layers and imply that the basal heat flux in the area is about 60 mW m⁻².     

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