Heat and mass transfer investigation of rotating hydrocarbons droplet which behaves as a hard sphere

AbstractThe steady state boundary layer equations around rotating pure hydrocarbon droplet are solved numerically. The droplet is simulated to behave as a hard sphere. The transfer equations are discretized using an implicit finite difference method where Thomas algorithm solves the system of algebraic equations. Moreover, dimensionless parameters of heat and mass transfer phenomena around a rotating hexane droplet concluded. The thickness of the boundary layer is unknown for this model and therefore, it is determined. Further, this work proposes correlations of Nusselt and Sherwood numbers for monocomponent hydrocarbon droplets in evaporation. These correlations consider the rotation phenomena and further, the variation of the thermophysical and transport properties in the vapour phase

Novel design of delta winglet pair vortex generator for heat transfer enhancement

Heat transfer is a naturally occurring phenomenon that can be greatly enhanced with the aid of vortex generators (VG). Three-dimensional numerical simulations of longitudinal vortex generators are performed to analyze heat transfer enhancement in parallel plate-fin heat exchanger. The shear-stress transport (SST) κ-ω model is adopted to model the flow turbulence. Empirical correlations from the open literature are used to validate empty channel simulations. First, numerical simulations are conducted for the classical delta winglet pair (DWP) which is introduced as the reference case in this study. Then, an innovative VG configuration, named inclined projected winglet pair (IPWP), is examined and it shows superior performance relative to the DWP. The IPWP exhibits similar heat transfer rates than that of the DWP but with lower pressure drop penalty due to its special aerodynamic design. The local performance is analyzed based on the streamwise distribution of Nusselt number and friction coefficient criteria in addition to vorticity. This study highlights the different mechanisms involved in the convective heat transfer intensification by generating more vortices using more aerodynamic VG shape while decreasing the pressure drop penalty

Heat transfer enhancement of inclined projected winglet pair vortex generators with protrusions

Heat transfer enhancement in parallel plate-fin heat exchanger is examined by performing three-dimensional numerical simulations of longitudinal vortex generators (VG) with protrusions. The turbulence is modeled using the shear-stress transport (SST) κ-ω model and validated with correlations and experimental data at Reynolds number equal to 4600. Hemi-spherical protrusions are inserted downstream two VG configurations: delta winglet type (DWP) and a new VG configuration named inclined projected winglet pair (IPWP), in various locations, leading to the definition of six different configurations. Based on the streamwise distribution of Nusselt number and friction coefficient criteria in addition to vorticity, the local performance is analyzed. Some VGs with protrusions are examined and show better performance relative to VGs standing alone. The present study highlights the different mechanisms involved in the convective heat transfer intensification by generating multiple interacting vortices while adding protrusions with low pressure drop penalty. Finally, it is found that the IPWP with protrusions, set downstream in the middle, bestows the best global performance with about 7.1% heat transfer enhancement compared to DWP configuration

Optimizing Hepatitis C Virus (HCV) Treatment in a US Colocated HCV/Opioid Agonist Therapy Program

Background A minority of patients with opioid use disorder are treated for hepatitis C virus infection (HCV). While colocated HCV and opioid agonist therapy (OAT) along with harm reduction can facilitate prevention and cascade to cure, there are few real-world examples of such embedded care models in the United States in the direct-acting antiviral (DAA) era. Methods We conducted a retrospective chart review to determine sustained virologic response (SVR) and reinfection rates during the first 5-year period of DAA availability among individuals tested and treated on-site at Rhode Island’s only nonprofit methadone maintenance program. Results Of 275 who initiated DAAs, the mean age (range) was 43 (22–71) years, 34.5% were female, 57.5% had genotype 1a, 23.3% had cirrhosis, and 92% were Medicaid recipients. SVR was 85.0% (232/273), while modified intent-to-treat SVR was 93.2% (232/249); 17 patients did not achieve SVR, 2 awaited SVR 12 weeks post-end-of-treatment, and 24 were lost to follow-up. Thirty reinfections were identified over 375.5 person-years of follow-up (rate, 7.99/100 person-years). The median time to first reinfection (interquartile range) was 128 (85.25–202.5) days. Before July 1, 2018, 72 patients accessed DAAs over 3.7 years; after Medicaid DAA restrictions were lifted, 109 patients accessed DAAs over 1.3 years. The Prior Authorization (PA) process requires many steps, differing across 11 RI insurers, taking 45–120 minutes per patient. Conclusions DAA treatment was effective among a marginalized population in an urban colocated OAT/HCV program. Removing DAA restrictions facilitates treatment initiation. The PA process remains a modifiable barrier to expanding capacity in the United States

Two human metabolites rescue a C. elegans model of Alzheimer's disease via a cytosolic unfolded protein response.

Age-related changes in cellular metabolism can affect brain homeostasis, creating conditions that are permissive to the onset and progression of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Although the roles of metabolites have been extensively studied with regard to cellular signaling pathways, their effects on protein aggregation remain relatively unexplored. By computationally analysing the Human Metabolome Database, we identified two endogenous metabolites, carnosine and kynurenic acid, that inhibit the aggregation of the amyloid beta peptide (Aβ) and rescue a C. elegans model of Alzheimer's disease. We found that these metabolites act by triggering a cytosolic unfolded protein response through the transcription factor HSF-1 and downstream chaperones HSP40/J-proteins DNJ-12 and DNJ-19. These results help rationalise previous observations regarding the possible anti-ageing benefits of these metabolites by providing a mechanism for their action. Taken together, our findings provide a link between metabolite homeostasis and protein homeostasis, which could inspire preventative interventions against neurodegenerative disorders

Novel design of triangular delta winglet pair for heat transfer enhancement

International audienc

The temperature distribution in Dean flow: an analytical approach

Most experimental techniques for measuring the temperature distribution in internal flows are intrusive and disturb the flow and heat transfer process. Numerical simulations of the flow field and heat transfer require the conjugate solution of the Navier-Stokes and energy equations, a highly compute-intensive process. Here an analytical approach is proposed to solve the energy equation in curved pipes that can provide the temperature field in this flow. Since it requires the flow velocity field, the wall temperature, and the temperature at only one point of the flow cross-section, this approach obtains the entire temperature field in the curved-pipe cross section using only one temperature probe in the flow. This technique can be applied to measurement of the temperature field, thus reducing the number of temperature probes necessary to one and minimizing the flow disturbance. For comparison with existing experimental data, here we apply this technique to the diameter of a curved-pipe cross section

Microvascular vasodilator properties of the angiotensin II type 2 receptor in a mouse model of type 1 diabetes

Diabetes Mellitus is associated with severe cardiovascular disorders involving the renin-angiotensin system, mainly through activation of the angiotensin II type 1 receptor (AT1R). Although the type 2 receptor (AT2R) opposes the effects of AT1R, with vasodilator and anti-trophic properties, its role in diabetes is debatable. Thus we investigated AT2R-mediated dilatation in a model of type 1 diabetes induced by streptozotocin in 5-month-old male mice lacking AT2R (AT2R). Glucose tolerance was reduced and markers of inflammation and oxidative stress (cyclooxygenase-2, gp91phox p22phox and p67phox) were increased in AT2R mice compared to wild-type (WT) animals. Streptozotocin-induced hyperglycaemia was higher in AT2R than in WT mice. Arterial gp91phox and MnSOD expression levels in addition to blood 8-isoprostane and creatinine were further increased in diabetic AT2R mice compared to diabetic WT mice. AT2R-dependent dilatation in both isolated mesenteric resistance arteries and perfused kidneys was greater in diabetic mice than in non-diabetic animals. Thus, in type 1 diabetes, AT2R may reduce glycaemia and display anti-oxidant and/or anti-inflammatory properties in association with greater vasodilatation in mesenteric arteries and in the renal vasculature, a major target of diabetes. Therefore AT2R might represent a new therapeutic target in diabetes