NUMERICAL SIMULATION OF GAS-SOLID FLOW IN AN INTERCONNECTED FLUIDIZED BED

The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed

parameters identification for scroll expander semi empirical model by using genetic algorithm

Abstract In this paper a small Organic Rankine Cycle (ORC) plant was tested under different operating conditions and by using refrigerants (R245fa) as working fluids. In particular, attention was posed towards the scroll expander of the power plant in order to identify experimental parameters to use in its predictive semi-empirical model. Experimental results obtained by imposing different operating conditions at the expander inlet section (i.e. temperature, pressure, mass flow rate) and different temperature at the condensation section, were used to validate the mathematical model. An in-house code (MatLab®/Scilab® based) using CoolProp® library for the accurate evaluation of fluid properties, was optimized by using a genetic algorithm implemented in modeFrontier® software. Thus, the validated model was used in predictive mode to evaluate the machine performances

Survey of trapped plasmas at the earth's magnetic equator

Analysis of data from the HPCE experiment on the AMPTEACCE satellite established probability distributions for trapped ions and electrons. Trapped 150 eV electrons occurred primarily in the dawn to noon local time sector, centered at L= 6. Trapped 50-150 eV ion distributions show strong L versus local time dependence, but are primarily found on the dayside (the dusk sector was not sampled for ions in this survey.) This local time dependence appears to reflect the L versus local time dependence of the plasmapause. The regions of peak occurrence probability for trapped ions were mutually exclusive with the high probability regions of trapped electrons. This offset in the location of trapped plasma species was seen frequently on a daily basis as well as in the statistical survey.http://archive.org/details/surveyoftrappedp00bracLieutenant, United States NavyApproved for public release; distribution is unlimited

heat exchanger design and optimization by using genetic algorithm for externally fired micro turbine

Abstract In this study, a new configuration where syngas produced by downdraft gasifier is feed directly in an externally fired air turbine is discussed. Attention was posed towards the critical component of this configuration: the heat exchanger. To achieve acceptable electrical efficiencies, high temperature of the air at the inlet turbine section was imposed. A code for heat exchanger design was built by using Matlab®, while the geometrical optimization was performed by using modeFRONTIER® by imposing a multi-objective function to maximize the overall heat transfer coefficient and minimize both costs and pressure drops across the equipment

Biofuel as Alternative Energy Carrier : Current Status, European Policies, Market and Production Level

Biofuels could be an appropriate way to reduce green house gas (GHG) emissions and to reduce the amount of fossil fuels burned. Two most common types of biofuels which are being developed and presently available on a commercial basis, are Ethanol and Biodiesel along with their derivatives. Biodiesel is the biofuel with the most rapid rate of market growth. European biodiesel industry is well established with a significant continuous increase in its production. In order to support the use of biodiesel and biofuel World-wide, especially, in developing countries where fossil energy use GHG emission will rise exponentially, there is a utmost necessity for international co-operation. The questions of biofuel industrial production, financial incentives, legislation, investment potential et. al. will be discussed in this publication.Використання біопалива може істотно знизити емісію парникових газів та скоротити кількість викопного палива, що спалюється. Найбільш поширеними та такими, що знайшли комерційне застосування, видами біопалива є біоетанол та біодизель з їх похідними. Застосування біодизеля характеризується найбільш активно зростаючим ринковим попитом, а Європейська біодизельна індустрія є стабільною з суттєвим постійним зростанням виробництва. Для забезпечення широкомасштабного, на світовому рівні, застосування біопалив, особливо в країнах, що розвиваються, де емісія парникових газів внаслідок використання викопних палив експоненційно зростає, вкрай необхідним є міжнародне співробітництво. У статті обговорюються питання промислового виробництва біопалива, фінансового стимулювання, законодавчої діяльності, інвестиційного потенціалу та ін.Использование биотоплива может существенно снизить эмиссию парниковых газов и сократить количество сжигаемых ископаемых топлив. Наиболее распространенными и нашедшими коммерческое применение видами биотоплива являются биоэтанол и биодизель наряду с их производными. Применение биодизеля характеризуется наиболее активно растущим рыночным спросом, а Европейская биодизельная индустрия является стабильной с существенным постоянным ростом производства. Для обеспечения широкомасштабного, на мировом уровне, применения биотоплив, особенно в развивающихся странах, где эмиссия парниковых газов вследствие использования ископаемых топлив экспоненциально возрастает, крайне необходимым является международное сотрудничество. В статье обсуждаются вопросы промышленного производства биотоплива, финансового стимулирования, законодательной деятельности, инвестиционного потенциала и др

Biomass Processing Research in Enea CR Trisaia (Italy) and in the Gas Institute of NAS of Ukraine

The main results of R&D activities on biofuel research area of Biomass laboratory at ENEA CR Trisaia and Combustion Processes Department of the Gas Institute of NAS of Ukraine such as synthesis gas, ethanol and produced gas production for natural gas substitution in industrial steam boilers are represented.Представлены основные результаты технологических исследований по биотопливной тематике лаборатории биомассы исследовательского центра ENEA CR Trisaia (Италия) и отдела процессов горения Института газа НАН Украины в области производства синтез-газа, этанола и генераторного газа как заменителя природного газа в промышленных паровых котлах.Представлено основні результати технологічних досліджень з біопаливної тематики лабораторії біомаси дослідного центру ENEA CR Trisaia (Італія) та відділу процесів горіння Інституту газу НАН України, а саме з виробництва синтез-газу, етанолу та генераторного газу як замінювача природного газу у промислових парових котлах

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI