scholarly journals Equilibrium moisture content of wood at different temperature/moisture conditions in the cladding of wooden constructions and in the relation to their reliability and service life

2010 ◽  
Vol 58 (2) ◽  
pp. 119-132
Author(s):  
Zdeňka Havířová ◽  
Pavel Kubů
Keyword(s):  
Service Life ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Vapor Condensation ◽  
Time Behavior ◽  
Wooden Frame ◽  
Water Vapor Condensation ◽  
Functional Reliability ◽  
Technical Assessment ◽  
Moisture Conditions

One of the natural properties of wood and wood-based materials is their soaking capacity (hy­gro­sco­pi­ci­ty). The moisture content of wood and building constructions of wood and wood based materials significantly influences the service life and reliability of these constructions and buildings. The equilibrium weight moisture content of built-in wood corresponding to temperature/moisture conditions inside the cladding has therefore a decisive influence on the basic requirements placed on building constructions. The wood in wooden frame cladding changes its moisture content depending on temperature and moisture conditions of the environment it is built into. The water vapor condensation doesn’t necessarily have to occur right in the wooden framework of the cladding for the equilibrium moisture content to rise over the level permissible for the reliable function of a given construction. In spite of the fact that the common heat-technical assessment cannot be considered fully capable of detecting the effects of these factors on the functional reliability of wood-based constructions and buildings, an extension has been proposed of the present method of design an assessment of building constructions according to the ČSN 73 0540 standard regarding the interpretation of equilibrium moisture content in relation to the temperature/moisture conditions and their time behavior inside a construction.

scholarly journals Reliability and service life of wood structures and buildings

2005 ◽  
Vol 53 (5) ◽  
pp. 39-52 ◽  
Author(s):  
Zdeňka Havířová ◽  
Pavel Kubů
Keyword(s):  
Service Life ◽  
Moisture Content ◽  
Energy Savings ◽  
Thermal Protection ◽  
Mechanical Resistance ◽  
Environment Protection ◽  
Wood Structures ◽  
Functional Reliability ◽  
Technical Evaluation ◽  
Moisture Conditions

Service life of constructions and buildings of wood is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC) of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability (ER1), energy savings and thermal protection (ER6) and hygiene, health and environment protection (ER3). To ensure the reliability of constructions and buildings for the period of their supposed service life a more profound analysis of constructions is necessary from the aspect of a global thermal/technical evaluation.

Influence of Moisture Sorption on Swelling of Mahogany (Swietenia macrophylla King) Wood

Holzforschung ◽  
2001 ◽  
Vol 55 (6) ◽  
pp. 590-594 ◽  
Author(s):  
R. Arévalo ◽  
R.E. Hernández
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Radial Direction ◽  
Moisture Sorption ◽  
Tangential Direction ◽  
Order Effects ◽  
Swelling Ratio ◽  
Swietenia Macrophylla ◽  
Dimensional Changes ◽  
Moisture Conditions

Summary Samples of mahogany wood (Swietenia macrophylla King) from Peru were used for moisture sorption tests associated with swelling tests at 25°C. Seven adsorption and five desorption moisture conditions were investigated to study the differences in swelling between adsorption and desorption curves at a given equilibrium moisture content. The results demonstrated that dimensional changes in the tangential direction and in volume were greater for desorption than for adsorption. The presence of these second order effects of moisture sorption in mahogany wood were not detected in the radial direction. Finally, the tangential/radial swelling ratio of this wood was lower in both states of sorption, and was lower in adsorption than in the desorption state.

scholarly journals A new aspects for project of subsequent thermal resistance extension at old-timer timbering constructions of wood

2006 ◽  
Vol 54 (2) ◽  
pp. 41-52
Author(s):  
Zdeňka Havířová
Keyword(s):  
Service Life ◽  
Thermal Resistance ◽  
Energy Savings ◽  
Thermal Protection ◽  
Mechanical Resistance ◽  
Environment Protection ◽  
Functional Reliability ◽  
Technical Evaluation ◽  
Moisture Conditions ◽  
Stability Energy

To ensure the reliability of subsequent thermal resistance extension at old-timer timbering constructions of wood for the period of their supposed service life a more profound analysis of construction is necessary from the aspect of a global thermal/technical evaluation. Service life of these buildings is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC) of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability, energy savings and thermal protection and hygiene, health and environment protection.

Analysis of the moisture content of maize kernels in over-ripe plants

2006 ◽  
Vol 54 (4) ◽  
pp. 425-430
Author(s):  
T. Árendás ◽  
L. C. Marton ◽  
P. Bónis ◽  
Z. Berzsenyi
Keyword(s):  
Linear Regression ◽  
Moisture Content ◽  
Grain Yield ◽  
Equilibrium Moisture Content ◽  
Weather Conditions ◽  
Positive Correlation ◽  
Maize Grain Yield ◽  
Maize Grain ◽  
Maize Kernels

The effect of varying weather conditions on the moisture content of the maize grain yield was investigated in Martonvásár, Hungary from late August to late September, and from the 3rd third of September to the 1st third of Novemberbetween 1999 and 2002. In every year a close positive correlation (P=0.1%) could be observed between the moisture content in late September and the rate of drying down in October. Linear regression was used each year to determine the equilibrium moisture content, to which the moisture content of kernels returned if they contained less than this quantity of water in late September and harvesting was delayed. In the experimental years this value ranged from 15.24-19.01%.

scholarly journals An Experimental Investigation of Water Vapor Condensation from Biofuel Flue Gas in a Model of Condenser, (1) Base Case: Local Heat Transfer without Water Injection

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 844
Author(s):  
Robertas Poškas ◽  
Arūnas Sirvydas ◽  
Vladislavas Kulkovas ◽  
Povilas Poškas
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Flue Gas ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Water Injection ◽  
Vapor Condensation ◽  
Base Case ◽  
Water Vapor Condensation ◽  
Condensing Heat Exchanger

Waste heat recovery from flue gas based on water vapor condensation is an important issue as the waste heat recovery significantly increases the efficiency of the thermal power units. General principles for designing of this type of heat exchangers are known rather well; however, investigations of the local characteristics necessary for the optimization of those heat exchangers are very limited. Investigations of water vapor condensation from biofuel flue gas in the model of a vertical condensing heat exchanger were performed without and with water injection into a calorimetric tube. During the base-case investigations, no water was injected into the calorimetric tube. The results showed that the humidity and the temperature of inlet flue gas have a significant effect on the local and average heat transfer. For some regimes, the initial part of the condensing heat exchanger was not effective in terms of heat transfer because there the flue gas was cooled by convection until its temperature reached the dew point temperature. The results also showed that, at higher Reynolds numbers, there was an increase in the length of the convection prevailing region. After that region, a sudden increase was observed in heat transfer due to water vapor condensation.

Equilibrium moisture content of dead fine fuels of selected central European tree species

2013 ◽  
Vol 22 (6) ◽  
pp. 797 ◽  
Author(s):  
Christian Schunk ◽  
Clemens Leutner ◽  
Michael Leuchner ◽  
Clemens Wastl ◽  
Annette Menzel
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Input Parameter ◽  
Fire Danger ◽  
Pedunculate Oak ◽  
Salt Solutions ◽  
Test Procedures ◽  
Climate Chamber ◽  
Central European ◽  
Fine Fuels

Fine fuel moisture content is a key parameter in fire danger and behaviour applications. For modelling purposes, equilibrium moisture content (EMC) curves are an important input parameter. This paper provides EMC data for central European fuels and adds methodological considerations that can be used to improve existing test procedures. Litter samples of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) were subjected to three different experiments using conditioning in a climate chamber and above saturated salt solutions. Climate chamber conditioning yielded the best results and can generally be recommended, however saturated salt solutions are able to produce lower relative humidities, which are relevant to forest fire applications as they represent the highest fire danger. Results were within the range of published sorption isotherms for forest fine fuels. A fairly clear gradation was present with higher EMC values in leaf litters than in needle litters. These differences are in accord with values from the literature and suggest general differences in the sorption properties of leaves and needles, which may be caused by differing chemical and physical properties. The influence of temperature on EMC described in the literature could be confirmed.

Water vapor condensation on binary mixed substrates: A molecular dynamics study

2021 ◽  
pp. 122281
Author(s):  
Zi-Jie Wang ◽  
Shao-Yu Wang ◽  
Dan-Qi Wang ◽  
Yan-Ru Yang ◽  
Xiao-Dong Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Water Vapor ◽  
Vapor Condensation ◽  
Mixed Substrates ◽  
Water Vapor Condensation
Sign in / Sign up

Export Citation Format

Share Document