Forced-convection condensation heat-transfer on horizontal integral-fin tubes including effects of liquid retention

PhDAccurate and repeatable heat-transfer data are reported for forced-convection filmwise condensation of steam and ethylene glycol flowing vertically downward over two single, horizontal instrumented integral-fin tubes and one plain tube. Vapour-side, heat-transfer coefficients were obtained by direct measurement of the tube wall temperature using specially manufactured, instrumented tubes with thermocouples embedded in the tube walls. Both tubes had fin height of 1.6 mm and fin root diameter of 12.7 mm, with fin thickness and spacing of 0.3 mm and 0.6 mm, respectively for the first tube and 0.5 mm and 1.0 mm respectively for the second. Tests were performed at atmospheric pressure for steam with nominal vapour velocities from 2.4 m/s to 10.5 m/s and at three pressures below atmospheric with nominal vapour velocities from 8.4 m/s to 57 m/s for steam and 13 m/s to 82 m/s for ethylene glycol. The data show that both the finned tubes provide an increase in heat flux at the same vapour-side temperature difference with increasing vapour velocity. Visual observations were made and photographs obtained of the condensate retention angle at each combination of vapour velocity and pressure. It was observed that the curvature of the meniscus was distorted by the increase in vapour velocity and in many cases, the extent of condensate flooding changed compared to its value in the quiescent vapour case. In parallel, experiments involving simulated condensation on finned tubes were conducted using horizontal finned tubes in a vertical wind tunnel. Condensate was simulated by liquid (water, ethylene glycol and R-113) supplied to the tube via small holes between the fins along the top of the tube. Downward air velocities up to 24 m/s were used and retention angles were determined from still photograph. Eight tubes with a diameter at the fin root of 12.7 mm were tested. Five tubes of which had fin height of 0.8 mm and spacing between fins of 0.5 mm, 0.75 mm, 1.0 mm, 1.25 mm and 1.5 mm and three tubes had fin height 1.6 mm with fin spacings 0.6 mm, 1.0 mm and 1.5 mm. The results were repeatable on different days and suggested, for all tubes and fluids, that the retention angle asymptotically approached a value around 80o to 85o (from either lower or higher values at zero vapour velocity) with increase in air velocity. Good agreement was found with observations taken during the condensation experiments

Science for gifted children in grade four.

Thesis (Ed.M.)--Boston Universit

The home helper : home service I

At head of title: University of Missouri College of Agriculture, Agricultural Extension Service Columbia, Missouri."January, 1947.""University of Missouri College of Agriculture and the United States Department of Agriculture Cooperating"--Page [32].Title from cover

Small articles for the girl's home : home furnishings I

Prepared by Madonna Fitzgerald and Louise Woodruff, Home Management Specialists, in collaboration with Jane Hinote, State Club Agent.At head of title: University of Missouri College of Agriculture, Agricultural Extension Service."June, 1946.""University of Missouri College of Agriculture and the United States Department of Agriculture Cooperating"--Page 17.Title from cover.Pillow cases -- Protector for comfort or blanket -- Covers for the dresser -- Cushion covers -- Washable chair seats and backs -- Luncheon cloth or set -- The luncheon sets -- Finishes for table linens -- The damask hem -- The fringed edge -- Decorative stitches -- Pictures for the girl's room -- Stools -- Wastebasket -- Orderly dresser drawers -- Score card for pillow cases -- Score card for dresser scarf

Perceptions and experiences of community-based healthcare professionals in the state of Qatar having do not attempt resuscitation discussions during the COVID-19 pandemic : Corrigendum

© 2024 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/In the published article, there was an error in the Ethics statement. The correct Ethics statement appears below. The studies involving human participants were reviewed and approved by the Medical Research Committee, Hamad Medical Corporation (MRC-01-20-433). Documentation of informed consent was waived by the HMC-IRB as per institutional and local requirements. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.Peer reviewe

Perceptions and experiences of community-based healthcare professionals in the state of Qatar having do not attempt resuscitation discussions during the COVID-19 pandemic

© 2023 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Introduction: The values and attitudes of healthcare professionals influence their handling of “do-not-attempt-resuscitation” (DNAR) orders, as does that of the families they interact with. The aim of this study was to describe attitudes, perceptions, and practices among community-based medical practitioners towards discussing cardiopulmonary resuscitation and DNAR orders with patients and their relatives, and to investigate if the COVID-19 pandemic affected their practice in having these discussions. Methods: This is a researcher-developed online survey-based study which aimed to recruit a convenience sample of respondents from a total population of 106 healthcare professionals working for the Mobile Healthcare Service (MHS), Hamad Medical Corporation Ambulance Service in the State of Qatar. Results: 33 family physicians, 38 nurses, and 20 paramedics (n = 91) responded to the questionnaire, of who around 40, 8, and 50%, respectively, had engaged in Do Not Attempt Resuscitation discussions during their work with MHS. 15% of physicians who had experience with Do Not Attempt Resuscitation discussions in Qatar felt that the family or patient were not open to having such discussions. 90% of paramedics thought that Do Not Attempt Resuscitation was a taboo topic for their patients in Qatar, and this view was shared by 75% of physicians and 50% of nurses. Per the responses, the COVID-19 pandemic had not affected the likelihood of most of the physicians or nurses (and 50% of the paramedics) identifying patients with whom having a Do Not Attempt Resuscitation discussion would be clinically appropriate. Discussion: Overall, for all three groups, the COVID-19 pandemic did not affect the likelihood of identifying patients with whom a Do Not Attempt Resuscitation discussion would be clinically appropriate. We found that the greatest barriers in having Do Not Attempt Resuscitation discussions were perceived to be the religious or cultural beliefs of the patient and/or their family, along with the factor of feeling the staff member did not know the patient or their family well enough. All three groups said they would be more likely to have a conversation about Do Not Attempt Resuscitation if barriers were addressed.Peer reviewe

Destabilisation of Sustainable Energy Transformations: Analysing Natural Gas Lock-in in the case of Germany

In recent years, natural gas has seen increased support in the context of climate change mitigation. Described as a ‘bridge fuel’ it is seen as aiding in the low-carbon energy transformation process. This is puzzling, given the high global warming potential of natural gas, which is composed almost entirely of the greenhouse gas methane. In this paper, we seek to explain the factors underpinning the political processes surrounding natural gas support, despite its unsuitability for climate mitigation. Drawing guidance from the pathways approach, and drawing on the broader institutional and regime literature, we analyse the role of actors and their networks, interests and politics as well as discourses and narratives. Our central claim is that support for natural gas is a result of institutional and incumbency lock-in, and has resulted from strategies that incumbent fossil fuel actors have deployed to secure their interests in the context of decarbonisation. We focus on liquefied natural gas (LNG) infrastructure in Germany, a representative case study for understanding the dynamics of natural gas support. The paper concludes by highlighting further avenues of research. In particular, we note specific misperceptions that need to be more openly contested in the discourse surrounding natural gas, in order to address the issue of natural gas lock-in

Implementing localised curriculum drawing on a funds of knowledge perspective: Teacher perceptions and challenges

In recent years in New Zealand, there has been a policy shift towards schools ‘localising’ the national curriculum to align with the context, aspirations, and knowledge of the local community and student population. In relation to mathematics education, this requires educators to understand and value the mathematical connections between diverse students’ funds of knowledge and use these to develop mathematical tasks. This article draws on interview responses from a case study of eight teachers from one low socio-economic, culturally diverse school to investigate their initial perceptions and actions to develop an appropriate localised mathematics curriculum drawing on diverse students’ funds of knowledge. The findings indicate that teachers viewed it as important to use real and relevant contexts in mathematics teaching. Interview responses indicated that both students and their families were seen as important sources of information. However, there were challenges for teachers to recognise students’ funds of knowledge related to mathematics beyond schooling or generic experiences

Comparison of Three Dimensional Velocity Models for Flanged Rectangular Hoods

The purpose of a local exhaust hood is to capture an airborne contaminant as close to the point of generation as possible and prevent it from entering the worker's breathing zone. Presently, local exhaust hood designs are based on capture velocity and practical experience. This process involves several defiencies, the most significant being the inability to determine the contaminant concentration in the worker's breathing zone as well as the inability to incorporate crossdrafts and source momentum characteristics. Three-dimensional velocity field models which predict the magnitude and direction of the velocity vector at any point in the field of flanged, rectangular exhaust hoods have been developed recently. This is a first step in determining the contaminant concentration in the worker's breathing zone and can, by vector addition, predict how crossdrafts and source momentum will effect contaminant capture. The purpose is to determine which of the available velocity field equations is the most accurate predictor of the velocity vector. This should help to determine optimal hood size, position and flow, resulting in more efficient and economical exhaust designs for industry. The theoretical basis for models in potential theory is presented and the limitations for industrial settings are discussed. The accuracy of the models was evaluated by measuring two-dimensional velocity vectors in the x-z and y-z planes of local exhaust hoods having aspect ratios of 1, 2, and 5. Measurements were made from 5% to 80% of the maximum hoodface velocity with an anemometer modified to permit rotation about its axis. The X, Y, and Z velocity components of each point were statistically compared to calcualted data. The ability to implement the models in computer programs is also discussed. Much work remains. The analysis can be expanded over a larger range of hood aspect ratios, and known crossdraft and source momentum vectors can be included.Master of Science in Public Healt