Numerical and experimental investigation of a vertical LiBr falling film absorber considering wave regimes and in presence of mist flow

The absorber represents the most critical component in absorption systems and one of the key issues. In this component complex heat and mass transfer phenomena during the absorption process takes place simultaneously. For this reason the development of mathematical models validated against experimental data always constitutes useful tools for the design and improvement of falling film absorbers. A testing device has been designed and built to reproduce absorption phenomena in vertical LiBr-H2O falling film absorbers with the primary objective to obtain experimental data. On the other hand, a mathematical model of falling film absorption of H2O vapour in LiBr aqueous solutions has been implemented. Wave regime is considered by including and solving the Free Surface Deflection Equation. The numerical results are validated using the experimental data. During the development of this work, the authors have paid careful attention to the verification of experimental data. Such verification consists of performing energy and mass balances in the fluid film side. Important discrepancies were found in our experimental data. Therefore, an extensive study was carried out in order to find the source of such errors. The conclusion is that there is a drag of LiBr solution in the water vapour which increases with the Re number. This mist flow cannot be measured experimentally, but can be evaluated in an indirect way. The mathematical models have been adapted in order to consider the influence of mist flow. On the other hand, in the literature there are not many experimental works related to falling film absorbers which expose enough information to verify the reliability of their experimental data.Peer ReviewedPostprint (author's final draft

Control strategy approach based on the operational results of a small capacity direct air -cooled LiBr -Water absorption chiller

The scope of this paper is to give a short overview of the state of the art regarding control strategies, identify the role of different operating conditions, and provide useful suggestions for the design and operation of a solar assisted absorption cooling system, in line to the European regulation as well as its directly related directives. The operation of a solar absorption cooling system under real conditions is subjected to various limitations regarding its ability to satisfy the required cooling demand, as well as to avoid certain internal conditions which would lead to problematic situations and jeopardize the smooth operation of the system - such as solution crystallization and water freezing. Thus, it is very important to define and refine new control operating strategies, from an internal and external perspective. Several control strategies are discussed, altogether with a new fuzzy logic approach, which shall be experimentally validated as future actions, due to its highly promising capability.Peer ReviewedPostprint (published version

Numerical and experimental study of absorption of H2O vapor in wavy falling film of LiBr aqueous solution in vertical tubes and in presence of non-absorbables

One of the main reasons for the discrepancies between theoretical predictions of absorption phenomena made by mathematical models when they are compared against experimental results under real conditions, are the presence of non-absorbable gases. It is well known that these non-absorbable gases inside the shell of the absorption chiller are produced mainly for two reasons: (i) air leakages (Oxygen-Nitrogen); (ii) gases produced by corrosion (Hydrogen). In order to evaluate the influence of the presence of non-absorbable gases, an experimental set-up which reproduces vapor absorption in a vertical falling film has been designed and built with a mass spectrometer analyzer. Parallelly, a mathematical model of falling film absorption of H2O by LiBr aqueous solution that considers the influence of non-absorbable gases has been implemented. The model is semi-empirical, based on Navier–Stokes equations together with energy and mass species simplified under the boundary layer hypotheses. Several experimental tests have been performed to determine the influence of the air concentration in the absorption performance. Moreover, a comparison of numerical results against experimental data has been performed under different working conditions with reasonable agreement.Peer ReviewedPostprint (author's final draft

Experimental evaluation of a pre-industrial air-cooled LiBr-H2O small capacity absorption machine

The paper studies thermal design and describes the experimental set-up of a domestic-scale prototype experimental cooling system based on a 7kW of nominal capacity single-stage small LiBr-H2O air-cooled absorption machine. The paper illustrates the characteristics based on a methodical procedure for the design and sizing of the small capacity air-cooled absorption machine.Peer ReviewedPreprin

Five-year results of accelerated partial breast irradiation: a single institution retrospective review of 289 cases

Purpose: the purpose of the study was to describe our institutional experience with accelerated partial breast irradiation (APBI) using multicatheter brachytherapy with high-dose-rate. We report 5-year survival outcomes, cosmesis, and treatment-related toxicity. Methods and materials: this included a retrospective review of patients who underwent breast-conserving surgery followed by APBI at our institution from 2004 to 2017. Results: a total of 289 patients were evaluated. Median followup was 72 months. Median age was 70 years. APBI was the only primary treatment in 86.2% of cases with early-stage breast cancer and a second conservative treatment in 13.8%. The implant was performed postoperatively in 213 patients (73.7%) and intraoperatively in 76 (26.3%). The most common radiation schemes were 10 fractions of 3.4 Gy and eight fractions of 4 Gy. Elderly or frail patients (10%) received a single 16 Gy dose. Of the 289 patients, 215 met Groupe Europ een de Curieth erapie-European Society for Radiotherapy and Oncology criteria for APBI; in this group, late side effects included Grade 2 (G2) fibrosis (14.8%), skin discoloration at the catheter points (8.8%), and telangiectasia (0.5%). The cosmetic result was considered excellent or good in 88.3% of cases. Five-year local control, disease-free, cancer-specific, and overall survival rates were 98.9%, 96.7%, 99.1%, and 95.6%, respectively. Conclusions: local control and survival outcomes at 5 years of followup in this group of well-selected patients were excellent, with low rates of treatment-related toxicity. These findings confirm the safety and effectiveness of APBI, even in elderly and frail patients. These results provide further support for the clinical use of APBI in suitable patients. 2021 Published by Elsevier Inc. on behalf of American Brachytherapy Society

The EU Center of Excellence for Exascale in Solid Earth (ChEESE): Implementation, results, and roadmap for the second phase

publishedVersio

Dimonis i dracs de la Ribera d'Ebre (II): El Ball de Diables d'Ascó

L'objectiu d'aquesta breu exposició és la de fer una mica més coneguda, si pot ser, la tradició de les colles de diables o dimonis i altres bèsties de foc en el panorama riberenc, a fi qur la seva coneixença i, l'aprofundiment en les seves arrels ens facin adonar de la rellevància d'aquest fet cultural singular de la tradició catalana que es remunta al s. XI

Dimonis i dracs de la Ribera d'Ebre (III): la Colla de Diables Sheron de Móra d'Ebre

La sèrie d'articles dedicats als diables i elements de foc de la comarca arriba a la tercera part amb la Colla de Diables Sheron de Móra d'Ebre, una colla que reprodueix a la dècada de 1990 la reviscolança de les tradicions populars catalanes durant la transició