Effects of mist fractions on heat transfer characteristics in a rotating roughened cooling passage

This paper investigates the effects of the mist fractions on heat transfer characteristics applied on a rotating U-channel with inclined ribs at an angle of 45°. This study has been conducted on five different mist percentages from 1 to 5 with a 1% increment at each step, and all of the cases have been investigated for Reynolds number values of 5000, 10000, 25000 and 40000. The numerical results obtained from the application of RNG k-ε turbulence model with enhanced-wall function were in good agreement with the experimental data of the smooth and ribbed channels both with and without mist addition. Results also demonstrated a 300% increase in the flow temperature difference and a noticeable increase in Nusselt number at each bend region and at the downstream of the leading edge around 25% and 110% respectively, at high mist fraction (5%); when compared with the case where only air was used. With %5 mist addition, the convective efficiency also reaches approximately 69%

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

Numerical investigation on heat transfer performance and flow characteristics in a roughened vortex chamber

In this study, an investigation of a vortex chamber was carried out to gain a full understanding of the nature of the vortex flow and the cooling capability inside the chamber. The paper discusses the effects on flow and heat transfer rates when the inside surface of the vortex chamber was roughened by adding flow turbulators to its wall. The turbulators took the shape of a rib with a square cross-section, the dimension of which varied between 0.25 mm and 2.00 mm. The paper also presents the results of a comparative investigation of jet impingement and vortex cooling on a concave wall using different parameters, such as the total pressure loss coefficient, Nusselt number and thermal performance factor, to evaluate the cooling effectiveness and flow dynamics. Furthermore, the entropy generation in swirl flow with the roughened wall was assessed over a wide range of Reynolds numbers. In this study, an investigation of a vortex chamber was carried out to gain a full understanding of the nature of the vortex flow and the cooling capability inside the chamber. The paper discusses the effects on flow and heat transfer rates when the inside surface of the vortex chamber was roughened by adding flow turbulators to its wall. The turbulators took the shape of a rib with a square cross-section, the dimension of which varied between 0.25 mm and 2.00 mm. The paper also presents the results of a comparative investigation of jet impingement and vortex cooling on a concave wall using different parameters, such as the total pressure loss coefficient, Nusselt number and thermal performance factor, to evaluate the cooling effectiveness and flow dynamics. Furthermore, the entropy generation in swirl flow with the roughened wall was assessed over a wide range of Reynolds numbers. The results show that surface roughness considerably influences the velocity distribution, heat transfer patterns and pressure drop in the vortex chamber. The highest thermal performance factor takes place at rib heights of 0.25 mm and 0.50 mm with a low Re number. Further increase in rib height has an adverse impact on thermal performance. At a Reynolds number lower than 50,000, it is highly recommended to use roughened vortex cooling to obtain the best thermal performance

Childhood meningitis in Kuwait in the era of post pneumococcal conjugate vaccination: A multicenter study

This is a retrospective study to evaluate epidemiology and etiologies of childhood meningitis in Kuwait after the routine introduction of the pneumococcal conjugate vaccine. The data was collected from 196 patients in the period of 2010–2014. Aseptic meningitis accounted for 51% of the cases, bacterial meningitis accounted for 29% cases and partially treated meningitis were 20%. Organisms causing bacterial meningitis were: Streptococcus pneumoniae 40.4%, Neisseria meningitidis 17.6%, Haemophilus spp. 12.2%, other gram positive or negative 19.3%, and Group B Streptococcus 8.8%. The hospitalization was complicated by admission to the ICU in 16.3% patients. Sequelae on discharge were seen in 4%, and 2.5% died of complications of meningitis. In children with pneumococcal meningitis, 48% were admitted to the ICU, 35% were discharged with sequelae and 13% died. In the era of post pneumococcal conjugate vaccination, S. pneumoniae remains the leading cause of bacterial meningitis with the greatest morbidity and mortality. Keywords: Meningitis, Children, Pediatric, Pneumococcal conjugate vaccine, Vaccine, Kuwai

Relationship between obesity and immunological parameters among students at the PSAU University-Alkharj, KSA

Obesity represents a major worldwide health problem, all aspects of which have not fully defined, nor fully understood.  In the current study, we investigated a population of university students in terms of the relationship between incidence of obesity in individuals (n=171),within this larger cohort (n=500), with the comorbidities that these high BMI individuals also carried. We also report important statistical differences in blood levels each of cardiac-related protein (CRP)(p=0.002), IL-6(p=0.005), &leptin(p=0.02), when we related the blood values with individual student BMIs which were used as a measure of obesity

Hematological and biochemical parameters among obese students at the PSAU, Alkharj, KSA

Management of obesity represents a global problem that challenges the provision of healthcare services in most countries. Saudi Arabia ranked number 29 on a 2007 list of countries with 6% of its population being overweight (BMI > 25).In a university setting, we studied hematological parameters (including whole blood counts, haemoglobin and platelets), the presence of basophilia, iron levels and lipid profiles in obese students, and also in non-obese student controls. We found a significant increase in whole blood count in obese compared to healthy individuals, and also found a high level of basophilia compared to healthy controls.  We also report that the obese student group suffered from low iron levels, and also a reduced total iron binding capacity, as compared to healthy controls. Levels of cholesterol and triglycerides was significantly higher in obese students compared to healthy controls. This study can be interpreted that universities across the Kingdom, and beyond, should consider targeting obesity management in their students to try to reduce the prevalence of obesity and associated disorders, and to support such healthcare programs by offering a variety of environmental, physical exercise and nutritional interventions

Hematological and Biochemical Parameters Among Obese Students at the PSAU, Alkharj, KSA

Management of obesity represents a global problem that challenges the provision of healthcare services in most countries. Saudi Arabia ranked number 29 on a 2007 list of countries with 6% of its population being overweight (BMI > 25).In a university setting, we studied hematological parameters (including whole blood counts, haemoglobin and platelets), the presence of basophilia, iron levels and lipid profiles in obese students, and also in non-obese student controls. We found a significant increase in whole blood count in obese compared to healthy individuals, and also found a high level of basophilia compared to healthy controls.  We also report that the obese student group suffered from low iron levels, and also a reduced total iron binding capacity, as compared to healthy controls. Levels of cholesterol and triglycerides was significantly higher in obese students compared to healthy controls. This study can be interpreted that universities across the Kingdom, and beyond, should consider targeting obesity management in their students to try to reduce the prevalence of obesity and associated disorders, and to support such healthcare programs by offering a variety of environmental, physical exercise and nutritional interventions