Dynamic modeling of a solar receiver/thermal energy storage system based on a compartmented dense gas fluidized bed

Fluidized beds may be considered a promising option to collection and storage of thermal energy of solar radiation in Concentrated Solar Power (CSP) systems thanks to their excellent thermal properties in terms of bed-to-wall heat transfer coefficient and thermal diffusivity and to the possibility to operate at much higher temperature. A novel concept of solar receiver for combined heat and power (CHP) generation consisting of a compartmented dense gas fluidized bed has been proposed to effectively accomplish three complementary tasks: collection of incident solar radiation, heat transfer to the working fluid of the thermodynamic cycle and thermal energy storage. A dynamical model of the system laid the basis for optimizing collection of incident radiative power, heat transfer to the steam cycle, storage of energy as sensible heat of bed solids providing the ground for the basic design of a 700kW th demonstration CSP plant

Fluidized Bed Combustion of Liquid Bio-Fuels: Application of Integrated Diagnostics for Micro-Explosions Characterization

A novel integrated diagnostic technique has been developed for the analysis of the “regime with microexplosions” that may be established during the low-temperature (T < 800 °C) fluidized bed combustion of liquid fuels. It consists of the comparison among three analogue data series: (i) pressure signals measured in the freeboard and high-pass filtered, (ii) oxygen molar fractions measured by zirconia-based probes at two elevations in the bed and in the splash region, and (iii) video frames of the bed surface recorded and purposely worked out. The integrated technique has been applied to the combustion of biodiesel at minimum fluidization and has proven to be a valid tool to provide the fingerprints of the mechanism of the low-temperature fluidized combustion of liquid fuels. The time series generated from the measured data sets have been analyzed with the aid of the Hurst’s rescaled range analysis, the V-statistic, and the Lyapunov exponents’ evaluation. The issue of localizing micro-explosions throughout bed, bubbles, and splash zone has been tackled by the V-statistic analysis, which has proven that the location of micro-explosions is just at the bed surface when T = 650 °C and moves deeper and deeper into the bed when its temperature increased to about 800 °C. The values found for the largest Lyapunov exponent in the time series demonstrate that the investigated system is not only dynamic but also chaotic in its nature

Hydrodynamic Characterization of GULF STREAM Circulation in a Pilot Scale Fluidized Bed Combustor

The present study addresses the hydrodynamics of a pilot-scale fluidized bed combustor with a focus on the establishment of "Gulf Stream" circulation patterns as a solids mixing promoter. Time-resolved pressure signals measured at different locations in the bed and in the plenum were analyzed in the time, frequency and phase-space domains. Results were matched against qualitative characterization of fluidization patterns by visual observation of the bed surface

Development of a Novel Concept of Solar Receiver/Thermal Energy Storage System Based on Compartmented Dense Gas Fluidized Beds

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Metric entropy in linear inverse scattering

The role of multiple views and/or multiple frequencies on the achievable performance in linear inverse scattering problems is addressed. To this end, the impact of views and frequencies on the Kolmogorov entropy measure is studied. This way the metric information that can be conveyed back from data to the unknown can be estimated. For the sake of simplicity, the study deals with strip scatterers and the cases of discrete angles of incidence and/or frequencies.&nbsp

Adjuvant benefit of a peptide-rich marine biology formula (LD-1227) in rheumatoid arthritis: a randomized, double-blind, controlled study

Introduction. There is a growing interest on non-chemical therapies among patients suffering from rheumatoid arthritis (RA), although safety, efficacy and properly designed studies are often lacking. Objective. The aim of the present investigation was to explore the clinical effectiveness of a marine nutraceutical, LD-1227, endowed by fine molecular biology studies, in the management of RA. Methods. The study design was a 12-week, randomized, double-blind study involving forty patients with stable longstanding RA who were randomized to receive either LD-1227 (n = 20) or Omega-3 (n = 20) on top of their established maintenance therapy. Results. At study recruitment and after 12 weeks of treatment, their Health Assessment Questionnaire (HAQ), erythrocyte sedimentation rate (ESR), visual analogue scale (VAS), and Disease Activity Score (DAS) 28, anxiety and depression analysis, C-reactive protein (CRP) levels, CXCL1, several pro-inflammatory interleukins levels and related gene expression, were compared between the two groups. Primary end point was the proportion of patients with response at weeks 12 as from the 20 % to 50% improvement criteria of the American College of Rheumatology (ACR20). At 12 weeks, ACR20 beneficial response was 81.0 % in LD-1227 group and 44 % in omega-3 group, (p&lt; 0.01). The superiority of LD-1227 appeared also when considering the ACR50 response at 12 weeks (62% in LD-1227 group as compared to 31 % in omega-3 group, p&lt; 0.01). The LD-1227-treated group displayed a significant improvement of VAS scale, HAQ score, morning stiffness and tender points (p &lt; 0.01 vs control and p &lt; 0.05 vs omega-3, respectively). From the biochemical viewpoint, patients in the LD-1227 group showed a lower level of CRP, IL-6, TNF-α, IL-1β, CXCL1, IFNγ, IL-15 and IP-10 and significant downregulation of related gene expressions. Unlike what observed in LD-1227 group, in the omega-3 group, CRP and DAS28 did not reach statistical difference. A substantial reduction of extra pain killer use was noted under LD-1227 treatment. Conclusion. One can conclude that LD-1227 may play a significant role on the management of RA and with a specrum and mechanisms of actions distinct from the canonical omega-3 while being devoid of any side effect or tolerability issues

A randomized, controlled trial on the effectiveness of a proprietary marine lipo-peptide formula vs omega-3 on cytokines profile, anxiety, and pain symptoms in patients with fibromyalgia

Objective: The aim of the present study in an RCT manner (physicians and patients) a novel lipo-peptide marine compound, LD-1227, on physical-, emotional- and functional-related symptomatic complaints in fibromyalgia patients as well as inflammatory cytokines profile and gene expression while using omega-3 as a control group. Methods: The following questionnaire-based or clinical evaluation-based parameters were evaluated: widespread pain index [WPI] patient global impression of change, total tender points [TTP], fibromyalgia impact questionnaire, Beck depression inventory, fatigue severity ratings, cognitive symptom severity, symptom severity score [SSS] and weekly pain intensity ratings. Additional biochemical and gene expression analysis of cytokines (IL6, TNF-α, IL-1β, MCP-1, IL-8, IL-13, IL-1α, and GM-CSF) was performed as well. Data were analyzed with either a paired t-test or the Wilcoxon signed rank test depending on the parametric or non-parametric distribution. Results: Comparing the data from before and after treatment for Group B indicated a statistically significant reduction (p=0.05) in TTP, WPI score, and SSS score. These data suggest a positive effect of a 3-month treatment with the LD-1227 but not omega-3 treatment on Fibromyalgia pain and related anxiety/depressive symptoms. Inspections of HRV and Cytokines found a statistically significant improvement after LD1227 treatment. Unlike the group supplemented with omega-3, the treatment with LD-1227 brought about a decrease in WPI and weekly pain intensity symptoms for the majority of participants. The pre-and post-treatment data for Group B indicated a statistically significant reduction (p=0.05) in TPC, WPI, and SSS scores. No adverse events were reported. Conclusion: These results provide the first indications that the LD-1227 treatment has a statistically significant effect on the recognized fibromyalgia diagnosis metrics of WPI, TTP, and SSS as well on inflammatory markers and parasympathetic balance

Numerical simulations of lateral solid mixing in gas-fluidized beds

We investigated the influence of design parameters and operational conditions on lateral solid mixing in fluidized beds adopting the Eulerian-Eulerian modeling approach. To quantify the rate at which solids mix laterally, we used a lateral dispersion coefficient (DsrDsr). Following the usual approach employed in the literature, we defined DsrDsr by means of an equation analogous to Fick׳s law of diffusion. To estimate DsrDsr, we fitted the void-free solid volume fraction radial profiles obtained numerically with those obtained analytically by solving Fick׳s law. The profiles match very well. Our results show that DsrDsr increases as superficial gas velocity and bed height increase; furthermore, it initially increases with bed width, but then remains approximately constant. The values of DsrDsr obtained numerically are larger than the experimental ones, within the same order of magnitude. The overestimation has a twofold explanation. On one side, it reflects the different dimensionality of simulations (2D) as compared with real fluidized beds (3D), which affects the degrees of freedom of particle lateral motion. On the other, it is related to the way frictional solid stress was modeled: we employed the kinetic theory of granular flow model for the frictional solid pressure and the model of Schaeffer (1987) for the frictional solid viscosity. To investigate how sensitive the numerical results are on the constitutive model adopted for the frictional stress, we ran the simulations again using different frictional models and changing the solid volume fraction at which the bed is assumed to enter the frictional flow regime (ϕmin)ϕmin). We observed that DsrDsr is quite sensitive to the latter. This is because this threshold value influences the size and behavior of the bubbles in the bed. We obtained the best predictions for ϕmin=0.50ϕmin=0.50. The results show that accurate prediction of lateral solid dispersion depends on adequate understanding of the frictional flow regime, and accurate modeling of the frictional stress which characterizes it

Studies on the potential antioxidant properties of Senecio stabianus Lacaita (Asteraceae) and its inhibitory activity against carbohydrate-hydrolysing enzymes

This study showed for the first time the antioxidant and hypoglycaemic properties of the methanol, n-hexane and ethyl acetate extracts from Senecio stabianus Lacaita, a plant that belongs to the Asteraceae family. The antioxidant activities were carried out using two different in vitro assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and 2,2\u2032-azinobis(3- ethylbenzthiazoline-6-sulphonate) (ABTS) test. The ethyl acetate extract showed the highest activity with inhibitory concentration 50% (IC 50) values of 35.5 and 32.7 \u3bcg mL -1 on DPPH test and ABTS test, respectively. This activity may be related to a good total phenol and flavonoid content. All extracts were also tested for their potential inhibitory activity of \u3b1-amylase and \u3b1-glucosidase digestive enzymes. The n-hexane extract exhibited the highest \u3b1-amylase inhibition with an IC 50 value of 0.21 mg mL -1. Through bioassay-guided fractionation processes seven fractions (A-G) were obtained and tested. Based on the phytochemical analysis, the activity of n-hexane extract may be related to the presence of monoterpenes and sesquiterpenes