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Wednesday, July 22, 2020 | History

2 edition of Principles of drying lumber at atmospheric pressure and humidity diagram found in the catalog.

Principles of drying lumber at atmospheric pressure and humidity diagram

Harry Donald Tiemann

Principles of drying lumber at atmospheric pressure and humidity diagram

by Harry Donald Tiemann

  • 322 Want to read
  • 21 Currently reading

Published by U.S. Dept. of Agriculture, Forest Service in Washington, D.C .
Written in English

    Subjects:
  • Lumber -- Drying.

  • Edition Notes

    Statementby Harry D. Tiemann.
    SeriesBulletin / U.S. Dept. of Agriculture. Forest Service -- 104, Bulletin (United States. Forest Service) -- 104.
    Classifications
    LC ClassificationsSD11 .A2 no. 104
    The Physical Object
    Pagination19 p., 1 folded leaf ;
    Number of Pages19
    ID Numbers
    Open LibraryOL22997050M
    LC Control Number12002211

    the temperature at which air with a given humidity will reach saturation when cooled without changing its pressure; the water vapor content of air. if air is slowly chilled, it will reach saturation. at that temperature, the air holds the max amount of water vapor possible. condensation will begin and dew will form! This banner text can have markup.. web; books; video; audio; software; images; Toggle navigation.

    This book discusses conventional as well as unconventional wood drying technologies. It covers fundamental thermophysical and energetic aspects and integrates two complex thermodynamic systems, conventional kilns and heat pumps, aimed at improving the energy performance of dryers and the final quality of dried lumber. save Save principle and mechanism of drying For Later. 2 2 upvotes, This is the minimum water held by the material that exerts an equilibrium vapor pressure less than the pure water at the same temperature. UNBOUND MOISTURE: This is the amount of water held by the material that exerts an equilibrium vapor pressure equal to that of pure.

    temperature and distance across the load in the high-temperature drying of Southern Pine. Twelve charges of 2 x 6 dimension lumber were dried to an average estimated moisture content of 12% using 4 different kiln schedules. The air temperature was recorded at 1-foot intervals across the load during drying. Graphs representing temperature drop. Chapter 3 Measurement of Humidity Definitions and units (1) Vapor pressure Vapor pressure is the partial pressure of water vapor in the air, expressed in hPa. (2) Saturation vapor pressure Saturation vapor pressure is the vapor pressure that is in a thermodynamic equilibrium with the surface of water or ice, expressed in hPa.


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Principles of drying lumber at atmospheric pressure and humidity diagram by Harry Donald Tiemann Download PDF EPUB FB2

Additional Physical Format: Online version: Tiemann, Harry Donald, b. Principles of drying lumber at atmospheric pressure and humidity diagram. from the Virginia Lumber Manufacturers Association.

Air Drying Air drying is the exposure of lumber to outside environmental conditions, with no artificial heating, control of velocity, or control of humidity. The lumber may be protected from the rain and sunlight with a small roof on each pile of lumber or by sheds.

Sheds greatly reduce File Size: KB. Kiln drying is accomplished in a closed chamber in which air temperature, relative humidity and airflow are controlled to dry lumber to a specified moisture content. The temperature for the drying is usually between °C depending on type, size and the later use of the lumber.

The subject of kiln drying lumber is probably one of the most hotly water equals the atmospheric pressure acting on the liquid. Standard pressure is taken to 1 atm.

(atmosphere) or mm of Hg. As we try to heat up lumber inside a dry kiln high humidity is a desirableFile Size: KB. Figure 2.—Humidity diagram. (By H. Tiemann, U. Forest Products Laboratory.) dried. The vapor, on the other hat. can, as its temperature drops, supply heat for evaporation only until the point of saturation is reached.

At the standard atmospheric pressure of pounds per square inch abso-lute, or zero pound. gage, the tempera. • Relat. ve H in Connection with Kiln" Drying; r- • "' and Conditioning of Lumber - A1thde gh the relative humidity has an importa ti: effect on the drying rate of a pile of lumber being air seasoned, this effect is less whe n lumber is kiln dried.

The rate of aar circiilation within a pile of lumber. Vacuum Drying: Basics and Application Article (PDF Available) in Chemical Engineering -New York- Mcgraw Hill Incorporated then Chemical Week Publishing Llc- (4) April w Reads.

Air- and Shed-drying Lumber J.E. Reeb and T.D. Brown EM E • Reprinted October The process of drying wood is the same for air- and kiln-drying, but in kiln-drying you have much greater control over air velocity, temperature, and humidity. Controls are much less when air-drying lumber.

Air-drying Air-drying means stacking lumber. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use.

When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method. There are two main reasons for drying wood: Woodworking When wood is used as a construction material, whether as a structural support in a building.

PROPERTIES OF WOOD AND STRUCTURAL WOOD PRODUCTS INTRODUCTION content of wood is a result of atmospheric conditions and depends on the relative humidity and temperature of the surrounding air. Under constant temperature and humidity conditions, an equilibrium moisture content.

solve the partial pressure of the water apvor p h from Eq. (20). We notice that it depends on the temperature and the partial pressure of the dry air p v= p v(T;p da): (21) We will now proof that to a very good accuracy p v= p v(T) (22) meaning that the dependency of the partial pressure of the water apvor on the partial pressure of the dry air.

industry practice for drying eastern hardwood lumber, in-cluding dimension items. Accent is on comparing methods for energy-saving management decisions, but practical guid-ance is also given to wood drying personnel.

Air drying, accelerated air drying, and kiln drying are covered. KEYWORDS: Hardwoods, drying, air drying, kiln drying. Conventional kiln drying is the dominating method in sawmilling due to low cost and wide adaptability, consequently drying more than 80% of all produced lumber in China (Li et al.

Loss of material. When you airdry lumber, it’s not unusual to lose up to 10 percent or more to drying defects.

Lumber defects occur when drying is too rapid, which leads to surface checks and end splits or when drying is too slow, which results in sticker stains and discoloration from fungal e air-drying is at the mercy of the weather, drying rates are difficult to control.

Practicalities in Air Drying Lumber Salim Hiziroglu Professor, Natural Resources and Ecology Management Kenny Hitch Extenion Forestry Specialist The drying of lumber is an important process that is re-quired for the efficient use of wood products. A freshly harvested tree will have a significant amount of moisture trapped within the wood cells.

The calculator computes many humidity attributes using ambient temperature and pressure, and relative humidity (RH). The attributes include mass of water vapor per mass of dry air mixing ratio, enthalpy, water vapor volume and mass as compared to dry and wet air in parts per million, dew point and wet-bulb temperatures, absolute humidity, water.

Microwave Drying. Microwave drying is a method gaining popularity owing to its superior advantages such as high heating rates, significant reduction in cooking time, more uniform heating, safe handling, ease of operation, and low maintenance in a small extent of sensory and nutritional changes compared with conventional thermal applications (Salazar-González et al., ; Vadivambal and Jayas.

Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or process is often used as a final production step before selling or packaging products. To be considered "dried", the final product must be solid, in the form of a continuous sheet (e.g., paper), long pieces (e.g., wood), particles (e.g., cereal grains.

through the m wide stack of lumber. Determine the properties of the air at state point 2 and compare them with those at state point 1. If the air is flowing at a rate of 2 meters per second, determine the drying rate assuming that the volume of the stack of cm-thick lumber is m3.

The stack is m wide x m long, and the boards are. Relative humidity in percent is the total water required for a volume of air divided by the amount of water that would be required to be totally saturate that volume of air. In drying, it is important to understand the role of both temperature and humidity and how they are related.

The Hydrosphere `Hydrosphere – water in the earth-atmosphere system Oceans and Salt Lakes % Ice Caps and Glaciers % (Not available for humans) % Subsurface Water (soil, groundwater) % Surface Water (rivers, freshwater lakes) % Atmosphere % `If all land were flat, the oceans would cover it to a depth of 3 km `If all atmospheric water were precipitated, it would cover.Slow drying of lumber.

Wet lumber of the type in Figure is slowly dried from an initial total moisture content of 50 wt% to a moisture content in equilibrium with atmospheric air at 25 C and 40% relative humidity. Determine: (a) unbound moisture in the wet lumber before drying in lb water/lb bone-dry lumber; (b) bound moisture in.and relative humidity.

Air is a vital component of our everyday lives. Air properties are important whether we are ventilating a livestock housing unit, drying grain, or determining relative humidity in the home.

In a livestock building, temperature, moisture, odors, and toxic or noxious gases must be controlled. Since the moisture holding ca.