Combustion Instability of Swirl Premixed Flame with Dielectric Barrier Discharge Plasma

The effects of plasma on the combustion instability of a methane swirling premixed flame under acoustic excitation were investigated. The flame image of OH planar laser-induced fluorescence and the fluctuation of flame transfer function showed the mechanism of plasma in combustion instability. The results show that when the acoustic frequency is less than 100 Hz, the gain in flame transfer function gradually increases with the frequency; when the acoustic frequency is 100~220 Hz, the flame transfer function shows a trend of first decreasing and then increasing with acoustic frequency. When the acoustic frequency is greater than 220 Hz, the flame transfer function gradually decreases with acoustic frequency. When the voltage exceeds the critical discharge value of 5.3 kV, the premixed gas is ionized and the heat release rate increases significantly, thereby reducing the gain in flame transfer function and enhancing flame stability. Plasma causes changes in the internal recirculation zone, compression, and curling degree of the flame, and thereby accelerates the rate of chemical reaction and leads to an increase in flame heat release rate. Eventually, the concentration of OH radicals changes, and the heat release rate changes accordingly, which ultimately changes the combustion instability of the swirling flame

Experimental and Numerical Study on Hydraulic Performance of Chevron Brazed Plate Heat Exchanger at Low Reynolds Number

Few experiments have been performed to investigate the hydraulic performance in a chevron brazed plate heat exchanger (BPHE) with the narrow channel at lower Reynolds number. The hydraulic characteristics of seven types of chevron BPHEs were investigated experimentally and numerical simulation revealed the effects of structural parameters on hydraulic performances. The correlations between friction factor f and Re were fitted out based on more than 500 sets of pressure drop data. The research results show that there is a power-law between f and Re; which has a similar trend but a different amplitude for different plates, and the exponent of the power-law could be approximate to a constant. Numerical results show that the pressure drop Δp is positively correlated with the corrugated angle and spacing, however, negatively correlated with the corrugated height. Research on the hydraulic performance is significant for the optimal design of BPHE

Empagliflozin in Patients with Chronic Kidney Disease

Background The effects of empagliflozin in patients with chronic kidney disease who are at risk for disease progression are not well understood. The EMPA-KIDNEY trial was designed to assess the effects of treatment with empagliflozin in a broad range of such patients. Methods We enrolled patients with chronic kidney disease who had an estimated glomerular filtration rate (eGFR) of at least 20 but less than 45 ml per minute per 1.73 m(2) of body-surface area, or who had an eGFR of at least 45 but less than 90 ml per minute per 1.73 m(2) with a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of at least 200. Patients were randomly assigned to receive empagliflozin (10 mg once daily) or matching placebo. The primary outcome was a composite of progression of kidney disease (defined as end-stage kidney disease, a sustained decrease in eGFR to < 10 ml per minute per 1.73 m(2), a sustained decrease in eGFR of & GE;40% from baseline, or death from renal causes) or death from cardiovascular causes. Results A total of 6609 patients underwent randomization. During a median of 2.0 years of follow-up, progression of kidney disease or death from cardiovascular causes occurred in 432 of 3304 patients (13.1%) in the empagliflozin group and in 558 of 3305 patients (16.9%) in the placebo group (hazard ratio, 0.72; 95% confidence interval [CI], 0.64 to 0.82; P < 0.001). Results were consistent among patients with or without diabetes and across subgroups defined according to eGFR ranges. The rate of hospitalization from any cause was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.86; 95% CI, 0.78 to 0.95; P=0.003), but there were no significant between-group differences with respect to the composite outcome of hospitalization for heart failure or death from cardiovascular causes (which occurred in 4.0% in the empagliflozin group and 4.6% in the placebo group) or death from any cause (in 4.5% and 5.1%, respectively). The rates of serious adverse events were similar in the two groups. Conclusions Among a wide range of patients with chronic kidney disease who were at risk for disease progression, empagliflozin therapy led to a lower risk of progression of kidney disease or death from cardiovascular causes than placebo