For wood the dominating mechanisms of moisture sorption are different in these two moisture ranges in the hygroscopic range water is primarily bound by hydrogen bonding in cell walls and in the over-hygroscopic range water uptake mainly occurs via capillary condensation outside cell walls in macro voids such as cell lumina and pit chambers Hygroscopic materials are those in which the equilibrium pressure of water vapor changes with moisture content and temperature such as food soil or wood etc Heat and moisture transports are coupled in heating of hygroscopic materials One of the major links between temperature and moisture changes is water evaporation

How to Stop Condensation in a Shipping Container

Moisture content of shipped goods: The hygroscopic goods in a shipping container can play a significant role in moisture levels Paper cardboard wood organic materials chilled foods and beverages and other commonly shipped products can release moisture when the temperature outside of the container drops

KEYWORDS: Wood Moisture transport Moisture gradient Monitoring Simulation 1 INTRODUCTION 123 Timber constructions are exposed to the variation of the ambient climate Wood is a hygroscopic material and reacts in a change of the moisture content mainly due to the change of the air temperature and relative humidity

Moisture content of shipped goods: The hygroscopic goods in a shipping container can play a significant role in moisture levels Paper cardboard wood organic materials chilled foods and beverages and other commonly shipped products can release moisture when the temperature outside of the container drops

Wood is a natural material that "lives" long after the tree has been felled If the air is too dry during storage and processing moisture is removed from the wood Unless additional air humidification is provided deformation distortion unevenness and surface cracks occur

If the behavior of hygroscopic capillary active materials is to be simulated correctly the moisture storage function shown in Fig 3 and the moisture-dependent liquid transport coefficients shown in Fig 5 are also needed For these coefficients the process-specific differentiation shown in the figure has proved advantageous

Theoretical analysis of moisture transport in wood as an

Jan 01 2011Moisture transport in an open porous hygroscopic material such as wood is a complex system of coupled processes For seasoned wood in natural climate three fully coupled processes active in the moisture transport are readily identified: (1) diffusion of vapor in pores (2) phase change from one state to another also called moisture sorption and (3) diffusion of bound water in wood tissue

The amount of water absorbed by a porous material (hygroscopic wetness or W hyg) increases as the moisture content of the air increases reaching a maximum when the relative humidity of the air is 100 percent For wood the maximum W hyg is about 30 percent (in terms of weight) whereas for wheat it is about 35 percent It is important to know

Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment which is usually at normal or room temperature If water molecules become suspended among the substance's molecules adsorbing substances can become physically changed e g changing in volume boiling point viscosity or some other physical

Oct 14 2012In the hygroscopic moisture range characteristic for all seasoned wood material in natural climate without direct contact to liquid water vapour alone is present in the porous system of wood For this most common case moisture transport is governed by three processes (Stamm 1960 ): diffusion of vapour in the porous system sorption and

The developed moisture pump with multilayer wood-like cellular networks and interconnected open channels is composed of a desiccant layer and a photothermal layer The desiccant layer exhibits an unprecedented moisture absorption capacity of 3 01 g gSUP-1/SUP at 90% relative humidity (RH) fast moisture absorption and transport rates

Jan 01 2011Moisture transport in an open porous hygroscopic material such as wood is a complex system of coupled processes For seasoned wood in natural climate three fully coupled processes active in the moisture transport are readily identified: (1) diffusion of vapor in pores (2) phase change from one state to another also called moisture sorption and (3) diffusion of bound water in wood tissue

Wood is a natural material that "lives" long after the tree has been felled If the air is too dry during storage and processing moisture is removed from the wood Unless additional air humidification is provided deformation distortion unevenness and surface cracks occur

Issues with wood as fuel: Low LHV high moisture low energy density non-homogeneous hygroscopic poor grindability Torrefaction addresses most of these issues delivering a fuel comparable to coal Torrefaction: thermochemical treatment process at 200-300•C to separate water VOCs hemicellulose in woody biomass Torrefied biomass:

Dynamic nonisothermal transport in hygroscopic porous

Dynamic nonisothermal transport in hygroscopic porous media: Moisture diffusion in wood Dynamic nonisothermal transport in hygroscopic porous media: Moisture diffusion in wood Avramidis Stavros Englezos Peter Papathanasiou Thanasis 1992-08-01 00:00:00 A model that predicts heat and moisture transfer in the hygroscopic range of a complex porous material such as wood was

This article presents experimental research on the moisture diffusivity in wood within the range of hygroscopic moisture This research was carried out on samples of three types of trees: Scots pine small-leaved linden and pedunculate oak

applications the over-hygroscopic moisture range is mainly relevant within wood-drying technology and for outdoor structures In wood-drying technology research on wood–water interactions mainly focused on moisture sorption and transport at high moisture levels for the purpose of developing

As a packaging material wood is hygroscopic i e it can absorb moisture and release it depending on the ambient humidity level of the air During transport and storage it is possible for boxes to be exposed to the outdoor climate and hence to be exposed to higher relative humidity or to direct precipitation

Dec 26 2016Knowledge on moisture transport in wood is important for understanding its utilization durability and product quality Moisture transport processes in wood can be studied by Nuclear Magnetic Resonance (NMR) imaging By combining NMR imaging with relaxometry the state of water within wood can be identified i e water bound to the cell wall and free water in the cell lumen/vessel

4 DTU Civil Engineering Technical University of Denmark Moisture transport Hygroscopic behavior of wood cell wall •Every cell wall layer adjacent to lumen rays etc is the dividing entity (surface) between the solid wood material and vapor phase •Water and cell wall material interacting with hydrogen bonds