Heat and Mass Transfer in a Permeable Fabric System Under Hot Air Jet Impingement

2010 ◽  
Author(s):  
Sangsoo Lee ◽  
Chanwoo Park ◽  
Devdatta Kulkarni ◽  
Sanjida Tamanna ◽  
Ted Knox
Keyword(s):  
Mass Transfer ◽  
Physical Properties ◽  
Personal Protective Equipment ◽  
Thermal Response ◽  
Jet Impingement ◽  
Protective Equipment ◽  
Jet Engine ◽  
Hot Air ◽  
Air Jet ◽  
Fabric System

Heat and mass transfer in a permeable fabric system used for Personal Protective Equipment (PPE) was investigated using hot air jet impingement conditions to mimic the jet exhaust of Short Take-Off and Vertical Landing (STOVL) aircraft. The STOVL aircraft uses a thrust-vectoring nozzle of the jet engine and a lift fan in order to vertically land and take off a short runaway. The jet engine exhaust is a new kind of thermal hazard for military personnel operating within an affected zone of the jet exhaust. An experimental approach was used to measure the thermal response of a fabric system consisting of permeable fabric samples and air pocket using a high-speed jet impingement. The jet impingement conditions consisted of two different temperatures: one of 100°C and another of 200°C at a jet impingement velocity of 32 m/s. Air was used as the working fluid. In this study, two permeable fabrics, (NOMEX IIIA and Cotton) commonly used for the Personal Protective Equipment (PPE) were investigated. The physical properties (porosity, permeability, Ergun coefficient, and density) and the thermo-physical properties (thermal diffusivity, thermal conductivity, and specific heat) of the fabrics were measured. A one-dimensional, two-medium formulation assuming thermal non-equilibrium between solid (fabric) and gas (air) phases in the fabric layer was used for the numerical analysis. The measurement results from the fabric experiment were used to define boundary conditions and adjust various heat transfer correlations and input data used in the numerical model. The experimental and numerical results of the temperatures of the fabric system were compared. The effects of the air temperature of the jet impingement on the thermal response of the fabric system were discussed.

FLOW FIELD IN A HOT AIR JET IMPINGEMENT OVEN ? PART 11: MULTIPLE IMPINGEMENT JETS

1999 ◽  
Vol 23 (3) ◽  
pp. 235-248 ◽  
Author(s):  
HEATHER E. MARCROFT ◽  
MURALI CHANDRASEKARAN ◽  
MUKUND V. KARWE
Keyword(s):  
Flow Field ◽  
Jet Impingement ◽  
Hot Air ◽  
Air Jet

Evaporation at a Liquid Surface Due to Jet Impingement

1986 ◽  
Vol 108 (2) ◽  
pp. 411-417 ◽  
Author(s):  
E. M. Sparrow ◽  
S. W. Celere ◽  
L. F. A. Azevedo
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Water Surface ◽  
Liquid Surface ◽  
Jet Impingement ◽  
Separation Distance ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Air Jet

Experiments were performed to determine mass transfer coefficients for evaporation from a water surface on which an air jet impinged. During the course of the experiments, parametric variations were made of the jet velocity and diameter, the separation distance between the jet origin and the water surface, the diameter of the water surface, and the degree of insulation of the water containment pan. It was found that for all of the investigated operating conditions, the dimensionless mass transfer coefficient varied with the 0.8 power of the jet Reynolds number. Furthermore, the transfer coefficient decreased linearly as the separation distance between the jet origin and the water surface increased, with the most significant decreases occurring at relatively small values of the surface-to-jet diameter ratio. At larger diameter ratios, the transfer coefficient was relatively insensitive to the separation. In general, the larger the diameter of the water surface, the lower the transfer coefficient. Comparisons with the literature showed that the dimensionless mass transfer coefficients for impingement on a liquid surface are lower than those for impingement on a solid surface.

Air jet impingement and hot air-assisted radio frequency hybrid drying of apple slices

LWT ◽  
2019 ◽  
Vol 116 ◽  
pp. 108517 ◽  
Author(s):  
Jing Peng ◽  
Xu Yin ◽  
Shunshan Jiao ◽  
Kangli Wei ◽  
Kang Tu ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Jet Impingement ◽  
Hot Air ◽  
Air Jet ◽  
Apple Slices

scholarly journals Study of Thermal Response of a Skin Stimulant Material with a Protective Fabric under a Hot Air Jet

2013 ◽  
Vol 56 ◽  
pp. 112-117
Author(s):  
A.A. Rezwan ◽  
S. Hossain ◽  
M.A. Islam
Keyword(s):  
Thermal Response ◽  
Hot Air ◽  
Air Jet

Impact of COVID-19 on Nuclear Medicine in Germany, Austria and Switzerland: An International Survey in April 2020

2020 ◽  
Vol 59 (04) ◽  
pp. 294-299 ◽  
Author(s):  
Lutz S. Freudenberg ◽  
Ulf Dittmer ◽  
Ken Herrmann
Keyword(s):  
Nuclear Medicine ◽  
Health Systems ◽  
Personal Protective Equipment ◽  
Large Scale ◽  
Diagnostic Procedures ◽  
Protective Equipment ◽  
Current Crisis ◽  
Web Based ◽  
Public Versus Private ◽  
The Impact

Abstract Introduction Preparations of health systems to accommodate large number of severely ill COVID-19 patients in March/April 2020 has a significant impact on nuclear medicine departments. Materials and Methods A web-based questionnaire was designed to differentiate the impact of the pandemic on inpatient and outpatient nuclear medicine operations and on public versus private health systems, respectively. Questions were addressing the following issues: impact on nuclear medicine diagnostics and therapy, use of recommendations, personal protective equipment, and organizational adaptations. The survey was available for 6 days and closed on April 20, 2020. Results 113 complete responses were recorded. Nearly all participants (97 %) report a decline of nuclear medicine diagnostic procedures. The mean reduction in the last three weeks for PET/CT, scintigraphies of bone, myocardium, lung thyroid, sentinel lymph-node are –14.4 %, –47.2 %, –47.5 %, –40.7 %, –58.4 %, and –25.2 % respectively. Furthermore, 76 % of the participants report a reduction in therapies especially for benign thyroid disease (-41.8 %) and radiosynoviorthesis (–53.8 %) while tumor therapies remained mainly stable. 48 % of the participants report a shortage of personal protective equipment. Conclusions Nuclear medicine services are notably reduced 3 weeks after the SARS-CoV-2 pandemic reached Germany, Austria and Switzerland on a large scale. We must be aware that the current crisis will also have a significant economic impact on the healthcare system. As the survey cannot adapt to daily dynamic changes in priorities, it serves as a first snapshot requiring follow-up studies and comparisons with other countries and regions.

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