scholarly journals Influence of Initial Moisture Content on Heat and Moisture Transfer in Firefighters’ Protective Clothing

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Dongmei Huang ◽  
Song He
Keyword(s):  
Moisture Content ◽  
Protective Clothing ◽  
Moisture Transfer ◽  
Burn Injury ◽  
Initial Moisture Content ◽  
Water Evaporation ◽  
Vapor Density ◽  
Degree Burn ◽  
Heat And Moisture ◽  
Second Degree

This paper presents a model for heat and moisture transfer through firefighters’ protective clothing (FPC) during radiation exposure. The model, which accounts for air gaps in the FPC as well as heat transfer through human skin, investigates the effect of different initial moisture contents on the thermal insulation performance of FPC. Temperature, water vapor density, and the volume fraction of liquid water profiles were monitored during the simulation, and the heat quantity absorbed by water evaporation was calculated. Then the maximum durations of heat before the wearer acquires first- and second-degree burns were calculated based on the bioheat transfer equation and the Henriques equation. The results show that both the moisture weight in each layer and the total moisture weight increase linearly within a given environmental humidity level. The initial moisture content in FPC samples significantly influenced the maximum water vapor density. The first- and second-degree burn injury time increase 16 sec and 18 sec when the RH increases from 0% to 90%. The total quantity of heat accounted for by water evaporation was about 10% when the relative humidity (RH) is 80%. Finally, a linear relationship was identified between initial moisture content and the human skin burn injury time before suffering first- and second-degree burn injuries.

Effects of Moisture on Temperature During Drying of Consolidated Porous Materials

1993 ◽  
Vol 115 (3) ◽  
pp. 724-733 ◽  
Author(s):  
F. Kallel ◽  
N. Galanis ◽  
B. Perrin ◽  
R. Javelas
Keyword(s):  
Moisture Content ◽  
Porous Materials ◽  
Moisture Transfer ◽  
Initial Moisture Content ◽  
Transfer Coefficients ◽  
One Dimensional ◽  
Excess Water ◽  
Brick And Mortar ◽  
Heat And Moisture ◽  
Simultaneous Heat

A one-dimensional model for simultaneous heat and moisture transfer in consolidated porous materials is solved for homogeneous brick and mortar slabs. It is validated by comparing numerically predicted moisture content and temperature evolutions with corresponding measured values. It correctly predicts that initially saturated slabs at 20°C which are suddenly placed in contact with air at 20°C and a relative humidity of 50 percent undergo a rapid transient reduction of their temperature down to 13°C due to the evaporation of excess water content. The model is used to study the effets of the initial moisture content and convection transfer coefficients on the minimum temperature of the slabs and on the duration of the transient.

The Influence of Heat and Moisture Transfer in Soil on the Performance of the Ground Heat Exchanger

2012 ◽  
Vol 594-597 ◽  
pp. 2120-2127
Author(s):  
Guo Min Shen ◽  
Chun Fang Lu ◽  
Yi Wang
Keyword(s):  
Thermal Properties ◽  
Heat Exchanger ◽  
Moisture Content ◽  
Moisture Transfer ◽  
Initial Moisture Content ◽  
Borehole Wall ◽  
Ground Heat Exchanger ◽  
Heat And Moisture Transfer ◽  
Soil Thermal Properties ◽  
Heat And Moisture

In this paper, a numerical heat and moisture transfer model (HMTM) and a pure conduction model (PCM) were established separately for unsaturated soil around the ground heat exchanger (GHE) and were numerically solved by finite volume method. The simulation results indicate that rejecting heat into soil can reduce moisture content in the vicinity of the borehole wall. When the initial moisture content is high, moister transfer has little effect on soil thermal properties. In this case, the results of the HMTM and the PCM are basically identical. On the contrary, when the initial moisture content is low, the thermal effect has significant influence on moisture transfer around the borehole wall, and the soil thermal properties will change correspondingly. In this case, there is a large difference between the results of these two models.

Experimental study of heat and moisture transfer in vertical air gap under protective clothing against dry and wet heat exposures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yun Su ◽  
Miao Tian ◽  
Yunyi Wang ◽  
Xianghui Zhang ◽  
Jun Li
Keyword(s):  
Natural Convection ◽  
Protective Clothing ◽  
Moisture Transfer ◽  
Heat Exposure ◽  
Air Gap ◽  
Gap Size ◽  
Heat And Moisture Transfer ◽  
Content Type ◽  
Wet Heat ◽  
Heat And Moisture

PurposeThe purpose of this paper is to study heat and steam transfer in a vertical air gap and improve thermal protective performance of protective clothing under thermal radiation and hot steam.Design/methodology/approachAn experiment-based model was introduced to analyze heat and moisture transfer in the vertical air gap between the protective clothing and human body. A developed test apparatus was used to simulate different air gap sizes (3, 6, 9, 12, 15, 18, 21 and 24 mm). The protective clothing with different air gap sizes was subjected to dry and wet heat exposures.FindingsThe increase of the air gap size reduced the heat and moisture transfer from the protective clothing to the skin surface under both heat exposures. The minimum air gap size for the initiation of natural convection in the dry heat exposure was between 6 and 9 mm, while the air gap size for the occurrence of natural convection was increased in the wet heat exposure. In addition, the steam mass flux presented a sharp decrease with the rising of the air gap size, followed by a stable state, mainly depending on the molecular diffusion and the convection mass transfer.Originality/valueThis research provides a better understanding of the optimum air gap under the protective clothing, which contributes to the design of optimum air gap size that provided higher thermal protection against dry and wet heat exposures.

scholarly journals Identification of heat and mass transfer processes in bread during baking

2005 ◽  
Vol 9 (2) ◽  
pp. 73-86 ◽  
Author(s):  
Ivanka Zheleva ◽  
Vesselka Kambourova
Keyword(s):  
Partial Differential Equations ◽  
Moisture Content ◽  
Differential Equations ◽  
Moisture Transfer ◽  
Partial Differential ◽  
Linear Partial Differential Equations ◽  
Mass Transfer Processes ◽  
Model Equations ◽  
Heat And Moisture ◽  
Simultaneous Heat

A mathematical model representing temperature and moisture content in bread during baking is developed. The model employs the coupled partial differential equations proposed by Luikov. Dependences of mass and thermal properties of dough on temperature and moisture content are included in the model. Resulting system of non-linear partial differential equations in time and one space dimension is reduced to algebraic system by applying a finite difference numerical method. A numerical solution of the model equations is obtained and simultaneous heat and moisture transfer in dough during baking is predicted. The changes of temperature and moisture content during the time of the process are graphically presented and commented.

Research on Condensation in Porous Wall Exposed to Hot Humid Climate

2012 ◽  
Vol 174-177 ◽  
pp. 2006-2011
Author(s):  
Zhen Hua Zhuo ◽  
Xing Guo Guo
Keyword(s):  
Moisture Content ◽  
Moisture Transfer ◽  
Strong Dependence ◽  
Porous Wall ◽  
Water Source ◽  
Vapor Condensation ◽  
Condensation Rate ◽  
Humid Climate ◽  
Heat And Moisture ◽  
Wet Zone

According to the work of Motakef and EI-Masri, the wall is divided into dry-wet-dry zones. Based on the heat and moisture transfer through porous media, considered the vapor condensation as a vapor sink, water source and heat source, coupled heat and moisture equations for wet zone were established. Closed-form analytical expressions for the condensation rate, moisture content and the time at which critical moisture content value is reached are obtained. The analysis has indicated that the condensation rate exhibits a strong dependence on the ratio of temperature drops across the wet zone to the square of that zone width and the maximum condensation rate value is reached at the boundary of wet zone close to lower temperature.

scholarly journals Spinal cord motor neuron plasticity accompanies second‐degree burn injury and chronic pain

2019 ◽  
Vol 7 (23) ◽  
Author(s):  
Siraj Patwa ◽  
Curtis A. Benson ◽  
Lauren Dyer ◽  
Kai‐Lan Olson ◽  
Lakshmi Bangalore ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Motor Neuron ◽  
Burn Injury ◽  
Degree Burn ◽  
Spinal Cord Motor Neuron ◽  
Second Degree
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