Simulation and optimization of screw feeder in a bubbling fluidized bed gasification reactor

A fluidized bed biomass gasification reactor is used to produce syngas from biomass and municipal wastes. Gasification is a flexible technology where many different types of feedstocks can be used. The University of South-Eastern Norway has a 20kW gasification reactor which is used to investigate the quality and quantity of the syngas produced using different types of feedstocks. At the present, the reactor has the challenge to supply feedstock to the reactor via transport screws. The main challenge consists of achieving continuous feeding and reduction in the feed rate. Therefore, this work is focused on the optimization of the screw feeder in the gasification reactor to obtain a reduced feed rate while maintaining a continuous feeding rate. The aim is to reduce the feed rate from approximately 8 kg/h to 3-4 kg/h without missing continuity of the feeding. A model of the screw feeder is developed using CAD software SolidWorks and the model is simulated using open-source simulation software LIGGGHTS to investigate feed rate and continuity using different combinations of transport screw parameters. The simulation results are processed using Excel and viewed graphically with the open-source visualization software ParaView. The simulation results are compared to the experimental measurements in the gasification reactor. The validated model is further used to investigate the feed rate with different combinations of transport screw parameters and the results are compared and discussed.publishedVersio

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Nanoparticle-induced pulmonary toxicity

10.1258/ebm.2010.010021Experimental Biology and Medicine23591025-1033EBMM

Symptoms and characteristics of individuals with profound hyponatremia: a prospective multicenter observational study

OBJECTIVES: To assess symptoms and characteristics of hyponatremia, the most common electrolyte disturbance in hospitalized individuals and a condition that is associated with substantial morbidity and mortality. DESIGN: Prospective observational multicenter study. SETTING: Two Swiss academic centers. PARTICIPANTS: Individuals with profound hypoosmolar hyponatremia (sodium>125 mmol/L) (N=298). MEASUREMENTS: All symptoms and complete medical history including current medications, therapy management, and in-hospital outcomes were recorded. RESULTS: The median age of all participants was 71 (interquartile range (IQR) 60-80), 195 (65%) were female, and mean serum sodium value on admission was 120 mmol/L (IQR 116-123 mmol/L). Frequent clinical symptoms were nausea (n=130, 44%), acute vomiting (n=91, 30%), generalized weakness (n=205, 69%), fatigue (n=175, 59%), gait disturbance (n=92, 31%), recurrent falls (n=47, 16%), and acute falls (n=60, 20%). Fractures were reported in 11 participants (4%). More-severe symptoms such as acute epileptic seizures and focal neurological deficits were identified in 16 (5%) and 17 (5%) participants, respectively. The most common comorbidities were hypertension (n=199, 67%), congestive heart failure (n=44, 15%), chronic renal failure (n=64, 21%), pulmonary disease (82, 28%), and central nervous system disease (n=114, 38%). During hospitalization, 12 (4%) participants died, and 103 (35%) needed treatment in the intensive care unit. CONCLUSION: A wide spectrum of symptoms accompanies profound hyponatremia. Most participants had moderate symptoms mirroring chronic hyponatremia with brain cell adaptation. Participants with profound hyponatremia had several comorbidities

Analysis Of Convective Heat Transfer Enhancement By Nanofluids: Single-Phase And Two-Phase Treatments

Nanofluids have been investigated regarding their advantages and potentialities for the purpose of increasing convective heat transfer rates inside thermal systems where they are used as working fluids. Researchers in thermophysics have investigated these fluids experimentally and numerically. This review provides extensive theoretical information concerning nanofluids in the single-phase and two-phase treatments. Important published works on nanofluid properties and correlations are summarized and reviewed in detail. Heat transfer enhancement by nanofluids is a challenging problem due to the difficulties inherent in the model of the physical mechanism of interaction between the paricles. Here the interaction between the phases is modeled by several two-phase models, and the results are given in graphical and tabular forms. Despite the advantages of the mixture model, such as imlementation of physical properties and less computational power requirements, some studies showed that the results of the single-phase and two-phase models are very similar. The main difference consists in the effect of the drift velocities of the phases relative to each other