Bubble dynamics and oxygen transfer in a speece cone

1998 ◽  
Vol 37 (2) ◽  
pp. 285-292 ◽  
Author(s):  
Daniel F. McGinnis ◽  
John C. Little
Keyword(s):  
Gas Phase ◽  
Oxygen Transfer ◽  
Process Model ◽  
Bubble Dynamics ◽  
Cost Model ◽  
Bubble Diameter ◽  
Water Flow Rate ◽  
Preliminary Design ◽  
Economic Optimization ◽  
Using Data

A model is developed that predicts bubble dynamics and oxygen transfer in a Speece Cone. The model is based on differential mass balances for both gas and water and requires a knowledge of cone dimensions, water flow rate, depth to the cone, and initial bubble diameter produced by the oxygen diffuser. The model calculates the oxygen transfer, nitrogen stripping, and gas-phase holdup within the cone. Experimental data for a Speece Cone have not been published; however, a modified version of the model is tested using data obtained from a hydrodynamically similar full-lift hypolimnetic aerator with good results. This process model, when coupled with a suitable cost model, should prove useful in the preliminary design and economic optimization of Speece Cone oxygenators.

Bubble dynamics and oxygen transfer in a hypolimnetic aerator

1998 ◽  
Vol 37 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Vickie L. Burris ◽  
John C. Little
Keyword(s):  
Gas Phase ◽  
Bubble Size ◽  
Oxygen Transfer ◽  
Bubble Dynamics ◽  
Water Flow Rate ◽  
Flow Rates ◽  
Wide Range ◽  
The City ◽  
Close Fit ◽  
Water Supply Reservoirs

A hypolimnetic aerator operating in one of the City of Norfolk's water supply reservoirs was tested. Dissolved oxygen (DO) profiles, water flow rate, and gas-phase holdup were measured over a wide range of applied air flow rates. A model that was developed to predict oxygen transfer in a Speece Cone was modified to conform to the conditions of the hypolimnetic aerator. By varying a single parameter (the initial bubble size) the model was found to provide a close fit to the experimental DO profiles as well as the observed gas-phase holdup. The model was used to show that a doubling in oxygen transfer may be achieved if initial bubble size is reduced from 5 mm to 2.5 mm. Knowing the initial bubble size, it should be possible to predict water velocity by incorporating the effect of momentum. Further work is now underway to test this approach and to examine the possibility of extending this generalized model to cover the range of hypolimnetic aeration and oxygenation devices.

Numerical modeling of the influence of bubbles on flow and heat transfer in the descending gas-liquid flow in a pipe

2012 ◽  
Vol 9 (1) ◽  
pp. 131-135
Author(s):  
M.A. Pakhomov
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Liquid Flow ◽  
Bubble Diameter ◽  
Gas Content ◽  
Two Phase ◽  
Eulerian Description ◽  
Flow And Heat Transfer ◽  
Gas Liquid Flow ◽  
The Mathematical Model

The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.

scholarly journals Perceptions of Caregiving: Racial Examinations of Resiliency and Stress

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 352-352
Author(s):  
Athena Koumoutzis ◽  
Kelly Cichy
Keyword(s):  
Racial Differences ◽  
Daily Living ◽  
Process Model ◽  
Well Being ◽  
Stress Process Model ◽  
Parental Caregiving ◽  
The Family ◽  
Using Data ◽  
Midlife Adults ◽  
Emotional Strain

Abstract Adult children are at risk of emotional strain when parental caregiving needs emerge. Pearlin’s Stress Process Model (1990) and caregiver studies suggest minority caregivers report lower subjective caregiving burden, however, few studies simultaneously consider both the stresses and rewards of caregiving. Using data from Wave II of the Family Exchange Study (N = 243), we examine racial differences in midlife adults’ perceptions (i.e., stress and rewards) of assisting their parents with activities of daily living (ADLs) and the associations between perceptions of ADL assistance and emotional well-being among adults who help their parents with ADLs. Compared to non-minority caregivers (M = 4.18, SD = 0.91), minority caregivers (M = 4.45, SD = 0.84) found it more rewarding to help their mother (t(314) = -2.54, p < .05), whereas non-minority caregivers (M = 2.25, SD = .1.27) found it more stressful to help their father than did minority caregivers (M = 1.64, SD = 0.99), t(162) = 3.01, p < .01). After controlling for demographics and ADL needs, linear regression analyses revealed that the stress of helping parents predicted depression (F(6, 189) = 5.30, p < .001) and race moderated the association (p < .01); the association was only significant for minority caregivers (p < .05). Implications will be discussed.

Hospital efficiency and patient satisfaction

2003 ◽  
Vol 16 (1) ◽  
pp. 24-38 ◽  
Author(s):  
G. H. Pink ◽  
M. A. Murray ◽  
I. McKillop
Keyword(s):  
Patient Satisfaction ◽  
Religious Affiliation ◽  
Cost Model ◽  
Hospital Efficiency ◽  
Small Hospital ◽  
Hospital Size ◽  
Patient Dissatisfaction ◽  
Teaching Status ◽  
Underlying Causes ◽  
Using Data

The objective of this study was to investigate the relationship between efficiency and patient satisfaction for a sample of general, acute care hospitals in Ontario, Canada. A measure of patient satisfaction at the hospital level was constructed using data from a province-wide survey of patients in mid-1999. A measure of efficiency was constructed using data from a cost model used by the Ontario Ministry of Health, the primary funder of hospitals in Ontario. In accordance with previous studies, the model also included measures of hospital size, teaching status and rural location. Based on the results of this study, at a 95% confidence level, there does appear to be evidence to suggest that an inverse relationship between hospital efficiency and patient satisfaction exists. However, the magnitude of the effect appears to be small. Hospital size and teaching status also appear to affect satisfaction, with lower satisfaction scores reported among non-teaching and larger hospitals. This study did not find any evidence to suggest that hospital location (rural versus urban) or religious affiliation contributed to reports of patient satisfaction in any way not explained by the other measures included in the study. The findings imply that low patient satisfaction cannot be explained by excessive management concentration on efficiency. Managers should analyse some of the underlying causes of patient dissatisfaction before reconfiguring resources. It may be beneficial in larger hospitals to study the aspects of care that patients have reported they prefer in small hospitals.

Power Transmission Analysis in Wireless Sensor Networks Using Data Aggregation Techniques

2018 ◽  
Vol 9 (4) ◽  
pp. 37-53
Author(s):  
Hradesh Kumar ◽  
Pradeep Kumar Singh
Keyword(s):  
Business Process ◽  
Process Model ◽  
Process Management ◽  
Power Transmission ◽  
Process Models ◽  
Model Matching ◽  
Matching Process ◽  
Effective Manner ◽  
Aggregation Techniques ◽  
Using Data

The process model matching is a critical step in many business process management activities. Process model matching consists of finding correspondences between activities of process models. This article presents a method for matching process model. The proposed method matches (i.e., aligns) two process models in three sequential steps. First, activities in the two process models are extracted. Second, the extracted activities are expanded using synonyms, hypernyms, and hyponyms of its composing words. These synonyms, hypernyms, and hyponyms are extracted from the WordNet thesaurus. Third, the expanded activities are compared using the Monge-Elkan similarity metric to detect matches. An empirical study was conducted on three well known datasets to evaluate the proposed method. The results of the experiment showed that the proposed method has the potential to match business process models in an effective manner when step two of the method is based on synonyms and hypernyms.

Droplet and Bubble Dynamics in Saturated FC-72 Spray Cooling

2005 ◽  
Author(s):  
Ruey-Hung Chen ◽  
David S. Tan ◽  
Kuo-Chi Lin ◽  
Louis C. Chow ◽  
Alison R. Griffin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Spray Cooling ◽  
Transfer Enhancement ◽  
Secondary Nucleation ◽  
Bubble Density ◽  
Experimental Findings ◽  
Small Bubbles ◽  
Nucleation Bubble

Droplet and bubble dynamics and nucleate heat transfer in saturated FC-72 spray cooling were studied using a simulation model. Using the experimentally observed bubble growth rate, submodels were assumed based on physical reasoning for the number of secondary nuclei entrained by the impinging droplets, bubble puncturing by the impinging droplets, bubble merging and the spatial distribution of secondary nuclei. The predicted nucleate heat transfer was in agreement with experimental findings. Dynamic aspects of the droplets and bubbles, which had been difficult to observe experimentally, and their ability in enhancing nucleate heat transfer were then discussed based on the results of the simulation. These aspects include bubble merging, bubble puncturing by impinging droplets, secondary nucleation, bubble size distribution and bubble diameter at puncture. Simply increasing the number of secondary nuclei is not as effective in enhancing nucleate heat transfer as when it is also combined with increased bubble puncturing frequency by the impinging droplets. For heat transfer enhancement, it is desirable to have as many small bubbles and as high a bubble density as possible.

Copper-mediated intra-ligand oxygen transfer in gas-phase complexes with 3-nitrotyrosine

2005 ◽  
Vol 40 (5) ◽  
pp. 608-614 ◽  
Author(s):  
Tomáš Vaisar ◽  
Jay W. Heinecke ◽  
Jennifer L. Seymour ◽  
František Tureček
Keyword(s):  
Gas Phase ◽  
Oxygen Transfer

Numerical and Experimental Investigation of Bubble Dynamics via Electrowetting-on-Dielectric (EWOD)

2016 ◽  
Author(s):  
Sheng Wang ◽  
Junxiang Shi ◽  
Hsiu-Hung Chen ◽  
Tiancheng Xu ◽  
Chung-Lung (C. L.) Chen
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Experimental System ◽  
Hydrophobic Surface ◽  
Numerical Results ◽  
The Body ◽  
Two Phase ◽  
Electrowetting On Dielectric

With the inspiration from electrowetting-controlled droplets, the potential advantages of electrowetting for bubble dynamics are investigated experimentally and numerically. In our experimental system, a 100 nanometer thin film gold metal was used as an electrode, and a 6.5 micrometer polydimethylsiloxane (PDMS) was spin-coated on the electrode acting both as an dielectric layer and hydrophobic surface. A two-phase model coupled with a electrostatics was used in our simulation work, where the body force due to the electric field acts as an external force. Our numerical results demonstrated that electrowetting can help the detachment of a small bubble by changing the apparent contact angle. Similar results were observed in our experiments that with electrowetting on dielectric, the contact angle of bubble on a hydrophobic surface will obviously decrease when a certain electrical field is applied either with a small size bubble (diameter around 1mm) or a relatively larger size bubble (diameter around 3 mm). When the applied voltage becomes high enough, both the experimental and numerical results demonstrate the characteristics of bubble detachment within a thin film liquid layer.

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