International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS

Long-term thermal conductivity of cyclopentane–water blown rigid polyurethane foams reinforced with different types of fillers

Producción CientíficaAn understanding of the long-term thermal conductivity of rigid polyurethane (RPU) foams presents great interest in the building field considering the conservation of energy efficiency. In this study, the effect of different types of particles (talc, diatomaceous earth and non-porous silica) on the thermal conductivity of RPU foams blown with cyclopentane and water as blowing agents was investigated during 3 years of aging. The characterization of the cellular structure shows how the addition of particles causes a cell size reduction of the foams, and consequently an enhancement of the thermal properties just after production. However, this initial reduction is not maintained, because each foam shows a different thermal conductivity evolution with time. We have found, for the first time, a relationship between the slope of the thermal conductivity versus time at the first measurements and the internal temperature reached during the foaming process. The evolution of the RPU foams in which higher internal temperatures were reached is more pronounced than in those RPU foams where lower foaming temperatures were observed. This effect is related to the kinetics of the diffusion of the gas occluded inside the cells and imposes a new criterion for the selection of particles to reduce the thermal conductivity of RPU foams; these additives should ideally decrease the temperature reached during the foaming process. Moreover, the effect of aging on the thermal conductivity is explained by using theoretical models.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (projects MAT2015-69234-R and RTC-2016-5285-5)Junta de Castilla y León (project VA275P18

Gas-flow distribution in bubbling fluidized beds: CFD-based analysis and impact of operating conditions

© 2017 Elsevier B.V. Gas-flow distribution plays a critical role in the performance of fluidized beds because it directly affects gas residence-time and solids mixing. However, measuring it accurately in the harsh conditions of larger reactors is not possible. Therefore, this study is focused on the development of a rigorous computational framework for quantifying gas-flow distribution during fluidization. To this end, fine-grid simulations are conducted for the bubbling fluidization of two distinct Geldart B particles - 1.15 mm LLDPE and 0.50 mm glass particles, at superficial gas velocities U/Umf = 2 and 3 in a 50 cm diameter bed. The two-fluid model (TFM) is employed to describe the solids motion efficiently and in-house developed tool MS3DATA (Multiphase-flow Statistics using 3D Detection and Tracking Algorithm) to compute detailed bubble statistics. The overall gas flow is divided into three phases: (a) dense flow in areas relatively rich is solids concentration (b) “visible” bubble flow associated with rising bubbles and (c) throughflow accounting for the gas flow which mostly bypasses through bubbles. It is found that conditions within the dense-phase depend largely on the particle properties while bubbling dynamics are significantly affected by superficial gas velocity. Calculations show that the throughflow increases in areas frequented by bubbles because the voidage distribution around bubbles increases the local dense-phase permeability. Throughflow may account for up to 40% of the overall gas flow, especially in the fluidization of large particles. This is not desirable because its residence-time is almost 2 × shorter (as compared to the dense flow) and contributes minimally to solids mixing. Finally, it is shown that in comparison to lab-scales, larger beds exhibit more homogeneous gas mixing. Insights from this study and the methodology developed will be useful in investigating gas flow distribution in complex fuel conversion systems