Flow structure and heat transfer of jet impingement on a rib-roughened flat plate

The jet impingement technique is an effective method to achieve a high heat transfer rate and is widely used in industry. Enhancing the heat transfer rate even minimally will improve the performance of many engineering systems and applications. In this numerical study, the convective heat transfer process between orthogonal air jet impingement on a smooth, horizontal surface and a roughened uniformly heated flat plate is studied. The roughness element takes the form of a circular rib of square cross-section positioned at different radii around the stagnation point. At each location, the effect of the roughness element on heat transfer rate was simulated for six different heights and the optimum rib location and rib dimension determined. The average Nusselt number has been evaluated within and beyond the stagnation region to better quantify the heat transfer advantages of ribbed surfaces over smooth surfaces. The results showed both flow and heat transfer features vary significantly with rib dimension and location on the heated surface. This variation in the streamwise direction included both augmentation and decrease in heat transfer rate when compared to the baseline no-rib case. The enhancement in normalized averaged Nusselt number obtained by placing the rib at the most optimum radial location R/D = 2 was 15.6% compared to the baseline case. It was also found that the maximum average Nusselt number for each location was achieved when the rib height was close to the corresponding boundary layer thickness of the smooth surface at the same rib position

National Healthcare-Associated Infections Report 2022 – Saudi Arabia

Background: Surveillance data are very essential for the effective use of available resources, the prioritization of infection control practices, and setting goals for intervention. The aim was to present the current rates of healthcare-associated infections (HAIs) and device utilization ratios (DUR) among the Saudi Ministry of health (MOH) hospitals. Methods: MOH analyzed the surveillance data collected from 106 MOH hospitals enrolled in the health electronic surveillance network (HESN) between January 2022 and December 2022. The surveillance methodology was similar to the methods of the US National Healthcare Safety Network (NHSN) and the Gulf Cooperation Council (GCC) center for infection control. Results: More than one million device-days of surveillance were analyzed. The rate of central line associated bloodstream infection (CLABSI) was 2.57 per 1000 central lines days. The rate of catheter-associated urinary tract infection (CAUTI) was 1.08 per 1000 urinary catheter days. The rate of ventilator-associated events (VAE) was 4.21 per 1000 ventilator days. The average rate of pediatric/neonatal ventilator-associated pneumonia (VAP) was 1.53 per 1000 ventilator days. The average DURs were 0.33 for central line, 0.61 for urinary catheter, 0.44 for ventilator in adult patients, and 0.26 in ventilator in pediatric/neonatal patients. In 238632 months of surveillance, the rate of dialysis events (DE) was 0.97 per 100 patient-months. In 86324 surgeries monitored, the rate of surgical site infection (SSI) was 0.87 per 100 surgeries surveyed. Conclusions: The current report can serve as a national benchmark for MOH hospitals and a regional benchmark for similar hospitals in the region