scholarly journals Multi-Criteria Modeling of Processes in a Vaporjet Condensation Turbine Ejector Mixing Chamber and Its Design

2020 ◽  
Vol 20 (3) ◽  
pp. 5-16
Keyword(s):  
Flow Rate ◽  
Optimality Criteria ◽  
Steam Consumption ◽  
Flow Area ◽  
Cross Sectional ◽  
Flow Parameters ◽  
Repair Costs ◽  
Mixing Chamber ◽  
Optimization Parameters ◽  
Turbine Equipment

The paper presents recommendations on designing an efficient mixing chamber and regulating air and steam flows in the elements of a steam-jet apparatus based on the results of multi-criteria modeling of gas-dynamic pro-cesses. The paper also reveals the possibilities to provide a greater reduction in losses, air suction into the turbine and equipment repair costs compared to the cases when individual criteria for increasing the steam turbine equipment efficiency are used. The selected calculation methods, i.e. innovative (multi-criteria) and standard (standard), have been analyzed comparatively. As a result of the methods evaluation, the authors se-lected the following indicators: increased energy efficiency of the turbine due to the prevention of air suction in the turbine seals; increased efficiency of condensing turbines; reduced repair and maintenance costs for the turbine and ejector due to the ejector mixing chamber cross-sectional area optimization. Based on the comparison, the best results were shown with the multi-criteria modeling according to the indicated parameters, the coefficients of the flow rate, working steam consumption, size reduction and increase in service life from 20 to 40 years. The innovative method requires a larger number of optimality criteria and the regulation of process pa-rameters and design geometry based on direct and feedback multi-criteria models. Using multi-criteria modeling, the authors determined the necessary composition of optimization parameters, i.e. the flow area of the designed mixing chamber, steam flow rate and thermodynamic flow parameters, as well as suction pressure.

Parametric Study of a Thermosyphon Loop Pressure Drop Model

2004 ◽  
Author(s):  
Jinsong Zhang ◽  
Jason Hugenroth ◽  
Issam Mudawar ◽  
Timothy S. Fisher
Keyword(s):  
Heat Flux ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Boiling ◽  
Current System ◽  
Experimental Studies ◽  
Two Phase ◽  
Flow Area ◽  
Cross Sectional

A closed loop two-phase thermosyphon has been modeled based on earlier experimental and numerical studies by Mukherjee and Mudawar [1, 2]. Unlike conventional thermosyphons in which the heat dissipating device is submerged in a pool of liquid coolant, the current system uses a flow boiling arrangement. The advantage is that for a given boiling surface area, the critical heat flux (CHF) can be increased. Parametric studies with respect to adiabatic section flow areas, boiler section flow area, and system height were performed. The maximum practical heat flux that is attainable is predicted, as well as other flow parameters such as mass flow rate, flow velocities and fluid quality existing the boiler. Performance enhancements relative to the original system, may be possible by introducing a divergent cross sectional area in the boiler section that increases the system mass flow rate. It can also, however, reduce the flow velocity in certain sections of the boiler, tending to reduce the boiler CHF. Experimental studies are recommended to determine if an actual improvement can be realized.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

scholarly journals Salivary flow rate and the risk of cognitive impairment among Korean elders: a cross-sectional study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Minh-Tung Do ◽  
Huong Vu ◽  
Jong-Koo Lee ◽  
Sang-Min Park ◽  
Joung-Sik Son ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Flow Rate ◽  
Salivary Flow ◽  
Cross Sectional Study ◽  
Community Dwelling ◽  
Salivary Flow Rate ◽  
Multivariable Logistic Regression Analysis ◽  
Sectional Study ◽  
Cross Sectional ◽  
Denture Status

Abstract Background Salivary function has been suggested to be associated with cognitive impairment. However, the effect of salivary flow rate (SFR) on cognitive impairment remains unclear. This study aimed to investigate whether SFR is associated with cognitive impairment among Korean elders. Methods This cross-sectional study included 649 elders aged 65 and older in the Korean community-dwelling population. Cognitive impairment was assessed using the Mini-Mental Status Examination. Unstimulated SFR was measured and dichotomized. Denture status, age, sex, education level, smoking, drinking, diabetes, hypertension, and obesity were considered confounders. Multivariable logistic regression analysis was applied to assess the adjusted association. Stratified analysis by sex and denture status was performed to clarify the effect modification. Results Participants without cognitive impairment showed a higher SFR level than those with cognitive impairment (0.81 mL/min for non-cognitive impairment versus 0.52 mL/min for cognitive impairment, p < 0.001). After controlling for confounders, participants with low SFR (< 0.3 mL/min) were more likely to have cognitive impairment by 1.5 times than participants with normal SFR (odds ratio [OR] = 1.5, confidence interval [CI] = 1.05–2.10). The association of low SFR with cognitive impairment was higher in women and dentate participants: about 10% higher in women (OR = 1.63, CI = 1.07–2.50) and about 22% higher in dentate participants (OR = 1.82, CI = 1.41–2.90). Conclusions Salivary flow rate is independently associated with cognitive impairment among Korean elders. The association was modified in females and dentate elders. Physicians and dentists should consider low SFR and cognitive impairment as a risk factor between them in clinics.

Optimization of chemical mechanical polishing parameters on surface roughness of steel substrate with aluminum nanoparticles via Taguchi approach

2014 ◽  
Vol 66 (6) ◽  
pp. 685-690 ◽  
Author(s):  
De-Xing Peng
Keyword(s):  
Flow Rate ◽  
Chemical Mechanical Polishing ◽  
Steel Substrate ◽  
Value Added ◽  
Mechanical Polishing ◽  
Slurry Flow ◽  
Average Roughness ◽  
Content Type ◽  
Optimization Parameters ◽  
Slurry Flow Rate

Purpose – The purpose of this paper is to investigate the effects of abrasive contents, oxidizer contents, slurry flow rate and polishing time in achieving a mirror-like finish on polished surfaces. Chemical mechanical polishing (CMP) is now widely used in the aerospace industry for global planarization of large, high value-added components. Design/methodology/approach – Optimal parameters are applied in experimental trials performed to investigate the effects of abrasive contents, oxidizer contents, slurry flow rate and polishing time in achieving a mirror-like finish on polished surfaces. Taguchi design experiments are performed to optimize the parameters of CMP performed in steel specimens. Findings – Their optimization parameters were found out; the surface scratch, polishing fog and remaining particles were reduced; and the flatness of the steel substrate was guaranteed. The average roughness (Ra) of the surface was reduced to 6.7 nm under the following process parameters: abrasive content of 2 weight per cent, oxidizer content of 2 weight per cent, slurry flow rate of 100 ml/min and polishing time of 20 min. Originality/value – To meet the final process requirements, the CMP process must provide a good planarity, precise selectivity and a defect-free surface. Surface planarization of components used to fabricate aerospace devices is achieved by CMP process, which enables global planarization by combining chemical and mechanical interactions.

scholarly journals IMPACT OF OBESITY ON PULMONARY FUNCTIONS AMONG YOUNG NON-SMOKER HEALTHY FEMALE OF SHAH ALAM, MALAYSIA

2018 ◽  
Vol 11 (10) ◽  
pp. 465
Author(s):  
Aniruddha Bhattacharjee ◽  
Ariitharan A/l Thygoo ◽  
Subramanian Rammohan
Keyword(s):  
Pulmonary Function ◽  
Flow Rate ◽  
Inverse Correlation ◽  
Forced Expiratory Volume ◽  
Female Students ◽  
Control Group ◽  
Contributing Factors ◽  
Cross Sectional ◽  
Pulmonary Functions ◽  
Healthy Female

Objectives: The sedentary lifestyle, physical inactivity, and unhealthy diet of Malaysian female have become important contributing factors to the rise of obesity. Studies on pulmonary function in relation to obesity are very few in Malaysia. Therefore, the study was aimed to evaluate the effect of obesity on pulmonary functions among young adult healthy female students of Shah Alam, Malaysia.Methods: A cross-sectional comparative study was conducted in a total of 100 (50 obese and 50 non-obese) adult non-smoker healthy female students aged 18–25 years. Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), FEV1 as a percentage of FVC (FEV1/FVC%), maximum midexpiratory flow rate (FEF 25–75%), and peak expiratory flow rate (PEFR) were measured using a computerized spirometer. Body weight, height, waist circumference (WC), and hip circumference (HC) were measured.Results: The mean FVC (L), FEV1 (L), FEV1/FVC ratio, FEF 25–75% (L/s), and PEFR (L/s) of obese group were marginally lower than non-obese control group, but the differences were not statistically significant. WC and waist–hip ratio exhibited significant (p<0.05) inverse correlation with all pulmonary function measurements except FEV1/FVC%. However, body mass index had no significant correlation with any spirometric variables in studied obese females.Conclusion: There was no significant effect of obesity on pulmonary functions in the studied Malaysian females. However, abdominal obesity had more impact on the impairment of pulmonary functions than overall relative obesity.

scholarly journals PERUBAHAN KECEPATAN ALIRAN AKIBAT VARIASI VOLUME VEGETASI DI BELOKAN SALURAN IRIGASI

2019 ◽  
Vol 2 (2) ◽  
pp. 114-122
Author(s):  
Muhammad Nasir ◽  
Eldina Fatimah ◽  
Masimin Masimin
Keyword(s):  
Energy Loss ◽  
Flow Rate ◽  
Water Depth ◽  
Local Community ◽  
Secondary Channel ◽  
Flow Area ◽  
Turn Angle ◽  
Irrigation Network ◽  
Speed Distribution ◽  
North Sumatra

D. I Timbang Deli is 520 Ha of flow area and 5000 meters of secondary channel is located in Deli Serdang Regency, North Sumatra Province. The turn of the irrigation network in overgrown vegetation on the cliffs and bottom of the channel, is expected to reduce the flow rate. The purpose of the study was to see the distribution of velocity, resistance and energy loss in the secondary channel due to vegetation. The method used is conducting surveys in the field by measuring water depth, vegetation volume and flow velocity. Trapezoidal channel with 36 m length, 1.45 lower width, 3.15 m upper width and 33,510 turn angle. The velocity measured in the middle and downstream regions across the channel is divided from points X1 to X5 with Q1 = 0.62m3/ sec and Q2 = 0.83 m3/sec. The results obtained in the speed distribution in Q1 Vmax mean X1 = 0.296 m/s and X5 = 0.199 m/s, the speed decreases due to the turn of 48.82%. On VV3 Vmaks the average is X4 = 0.216 m/sec and (X1 and X2) = 0,000 m/sec, the volocity decreases due to the presence of vegetation between X1, X2 and X5 at Q1 = 100%. In Q2 the average VV0 Vmax condition of the flow X1 = 0.477 m/s and X5 = 0.323 m/s between X1 and X5 the volocity decreases due to turn 28.45%. VV3 Vmax conditions on average X5 = 0.312 m / s and X1 = 0.000 m / s, between X1 and X5 the speed decreases due to the presence of 100% vegetation. In connection with the above results, with this research the local community and local government can carry out cleaning on the channel on a scale basis.

Effect of N2 Flow Rate on Structure and Morphology of (Ti,Cr)N Thin Films Deposited by Unbalanced Magnetron Co-Sputtering

2012 ◽  
Vol 488-489 ◽  
pp. 432-436
Author(s):  
Chutima Paksunchai ◽  
Somyod Denchitcharoen ◽  
Surasing Chaiyakun ◽  
Pichet Limsuwan
Keyword(s):  
Thin Films ◽  
Flow Rate ◽  
Columnar Structure ◽  
Root Mean Square Roughness ◽  
Cross Sectional ◽  
X Ray ◽  
Force Microscopy ◽  
Unbalanced Magnetron ◽  
Crystallite Sizes ◽  
Scherrer Formula

The (Ti,Cr)N thin films were deposited with various N2 flow rates on silicon wafers by reactive unbalanced magnetron co-sputtering without heating and biasing substrates. The effects of N2 flow rate on the structure and morphologies of the films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDS). The results revealed that the (Ti,Cr)N thin films formed solid solutions with the fcc structure. The crystallite sizes calculated from Scherrer formula are about 13 nm. The root-mean-square roughness (Rrms) and the thickness (Tth) of the films were slightly decreased with the increase in N2 flow rate. The cross-sectional morphology showed columnar structure corresponding to zone 2. In addition, the N atomic concentration was also increased with the increase in N2 flow rate.

scholarly journals Measurement of Permeability in Horizontal Direction of Open-Graded Friction Course with Rutting

2020 ◽  
Vol 12 (16) ◽  
pp. 6428
Author(s):  
Jaewon Yoo ◽  
Tan Hung Nguyen ◽  
Eungu Lee ◽  
Yunje Lee ◽  
Jaehun Ahn
Keyword(s):  
Hydraulic Gradient ◽  
Testing Equipment ◽  
Horizontal Direction ◽  
Flow Area ◽  
Cross Sectional ◽  
Traffic Loading ◽  
Test Methodology ◽  
Discharge Velocity ◽  
Open Graded Friction Course ◽  
Horizontal Permeability

Although the permeability of open-graded friction course (OGFC) materials in the transverse direction and the reduction in permeability associated with long-term traffic loading are important issues, they have remained under researched thus far. In this study, testing equipment and procedure were developed to evaluate the permeability of an OGFC specimen along the horizontal direction and its reduction due to rutting. Horizontal permeability tests were conducted by varying the hydraulic gradient of specimens with porosities of 19.6%, 15.6%, and 10.3%. The reduction in cross-section due to traffic loading was simulated via a wheel tracking test, and the permeability was subsequently evaluated. The reliability of test methodology was successfully verified; the tendency of the relationship between discharge velocity and hydraulic gradient was in good agreement with existing research results. The reduction in cross-sectional flow area due to rutting decreased and the horizontal permeability. The test results using developed testing equipment will enable efficient OGFC design.

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