ASHRAE HVAC APPLICATIONS IP CH 21-2015 TEXTILE PROCESSING PLANTS.pdf
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1、21.1CHAPTER 21TEXTILE PROCESSING PLANTSTerminology 21.1Fiber Making. 21.1Yarn Making 21.2Fabric Making. 21.3Air-Conditioning Design. 21.4Energy Conservation. 21.7HIS chapter covers (1) basic processes for making syntheticTfibers, (2) fabricating synthetic fibers into yarn and fabric, (3)relevant typ
2、es of HVAC and refrigerating equipment, (4) healthconsiderations, and (5) energy conservation procedures.Most textile manufacturing processes may be placed into one ofthree general classifications: synthetic fiber making, yarn making, orfabric making. Synthetic fiber manufacturing is divided into st
3、apleprocessing, tow-to-top conversion, and continuous fiber processing;yarn making is divided into spinning and twisting; and fabric makingis divided into weaving and knitting. Although these processes vary,their descriptions reveal the principles on which air-conditioningdesign for these facilities
4、 is based.1. TERMINOLOGYThe following is only a partial glossary of terms used in the textileindustry. For more complete terminology, consult the sources in theBibliography or the Internet search engine of your choice.Air permeability. Porosity, or ease with which air passes throughmaterial. Air per
5、meability affects factors such as the wind resistanceof sailcloth, air resistance of parachute cloth, and efficiency of vari-ous types of air filtration media. It is also a measure of a fabricswarmness or coolness.Bidirectional fabric. A fabric with reinforcing fibers in twodirections: in the warp (
6、machine) direction and filling (cross-machine) direction.Calender. A machine used in finishing to impart various surfaceeffects to fabrics. It essentially consists of two or more heavy rollers,sometimes heated, through which the fabric is passed under heavypressure.Denier. The weight, in grams, of 9
7、000 m (29,528 ft) of yarn.Denier is a direct numbering system in which lower numbers repre-sent finer sizes and higher numbers the coarser sizes. Outside theUnited States, the Tex system is used instead.Heddle. A cord, round steel wire, or thin flat steel strip with aloop or eye near the center, thr
8、ough which one or more warp threadspass on the loom, so that thread movement may be controlled inweaving. Heddles are held at both ends by the harness frame. Theycontrol the weave pattern and shed as the harnesses are raised andlowered during weaving. Lubricant. An oil or emulsion finish applied to
9、fibers to preventdamage during textile processing, or to knitting yarns to make themmore pliable.Machine direction. The long direction within the plane of thefabric (i.e., the direction in which the fabric is being produced by themachine).Pick. A single filling thread carried by one trip of the weft
10、 inser-tion device across the loom. Picks interface with the warp ends toform a woven fabric.Reed. A comblike device on a loom that separates the warp yarnsand also beats each succeeding filling thread against those alreadywoven. The space between two adjacent wires of the reed is called adent. The
11、fineness of the reed is calculated by the number of dentsper inch: the more dents, the finer the reed.Selvage. The narrow edge of woven fabric that runs parallel to thewarp. It is made with stronger yarns in a tighter construction than thebody of the fabric, to prevent raveling. A fast selvage enclo
12、ses all orpart of the picks; a selvage is not fast when the filling threads are cutat the fabric edge after each pick.Shuttle. A boat-shaped device usually made of wood with ametal tip that carries filling yarns through the shed in the weavingprocess.Tex. The mass, in grams, of 1000 m (3281 ft) of f
13、abric. Used pri-marily outside the United States. See also Denier.Warp. The set of yarn in all woven fabrics, running lengthwiseand parallel to the selvage, interwoven with the filling.2. FIBER MAKINGProcesses preceding fiber extrusion have diverse ventilating andair-conditioning requirements based
14、on principles similar to thosethat apply to chemical plants.Synthetic fibers are extruded from metallic spinnerets and solid-ified as continuous parallel filaments. This process, called continu-ous spinning, differs from the mechanical spinning of fibers or towinto yarn, which is generally referred
15、to as spinning.Synthetic fibers may be formed by melt-spinning, dry-spinning, orwet-spinning. Melt-spun fibers are solidified by cooling the moltenpolymer; dry-spun fibers by evaporating a solvent, leaving the poly-mer in fiber form; and wet-spun fibers by hardening the extruded fil-aments in a liqu
16、id bath. The selection of a spinning method is affectedby economic and chemical considerations. Generally, nylons, polyes-ters, and glass fibers are melt-spun; acetates dry-spun; rayons andaramids wet-spun; and acrylics dry- or wet-spun.For melt- and dry-spun fibers, the filaments of each spinneret
17、areusually drawn through a long vertical tube called a chimney orquench stack, within which solidification occurs. For wet-spunfibers, the spinneret is suspended in a chemical bath where coagula-tion of the fibers takes place. Wet-spinning is followed by washing,applying a finish, and drying.Synthet
18、ic continuous fibers are extruded as a heavy denier tow forcutting into short lengths called staple or somewhat longer lengthsfor tow-to-top conversion, or they are extruded as light denier fila-ments for processing as continuous fibers. Oil is then applied tolubricate, give antistatic properties, a
19、nd control fiber cohesion. Theextruded filaments are usually drawn (stretched) both to align themolecules along the axis of the fiber and to improve the crystallineThe preparation of this chapter is assigned to TC 9.2, Industrial AirConditioning.21.2 2015 ASHRAE HandbookHVAC Applicationsstructure of
20、 the molecules, thereby increasing the fibers strengthand resistance to stretching.Heat applied to the fiber when drawing heavy denier or high-strength synthetics releases a troublesome oil mist. In addition, themechanical work of drawing generates a high localized heat load. Ifthe draw is accompani
21、ed by twist, it is called draw-twist; if not, itis called draw-wind. After draw-twisting, continuous fibers may begiven additional twist or may be sent directly to warping.When tow is cut to make staple, the short fibers are allowed toassume random orientation. The staple, alone or in a blend, is th
22、enusually processed as described in the Cotton System section. How-ever, tow-to-top conversion, a more efficient process, has becomemore popular. The longer tow is broken or cut to maintain parallel ori-entation. Most of the steps of the cotton system are bypassed; the par-allel fibers are ready for
23、 blending and mechanical spinning into yarn.In the manufacture of glass fiber yarn, light denier multifilamentsare formed by attenuating molten glass through platinum bushingsat high temperatures and speeds. The filaments are then drawntogether while being cooled with a water spray, and a chemical s
24、izeis applied to protect the fiber. This is all accomplished in a singleprocess prior to winding the fiber for further processing.3. YARN MAKINGThe fiber length determines whether spinning or twisting must beused. Spun yarns are produced by loosely gathering synthetic staple,natural fibers, or blend
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