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全部资讯   / 烘燥的基本原理

烘燥的基本原理

2013-07-24 10:36:50

<section class="_135editor" data-role="paragraph" style="max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  在织物烘燥的全过程中,必须具备以下两个条件,才能满足烘燥过程的进行。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  (1)蒸发织物中水分所必需的热量。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  (2)为带走蒸发水分所必需的水蒸气分压力梯度。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  当以上两个条件协调一致时,可达到最理想的烘燥效果。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  图5-1是织物在烘燥过程中温度、水分及烘燥速度与烘燥时间的关系曲线。由图可知,织物进入烘燥机时,其温度为T1 ,含水分d1 。经过一段时间t1 的烘燥后,织物的温度上升至T2 ,水分降为d2 。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  在t1 这段时间中,烘燥机提供给织物的热能大部分用于织物升温,为烘燥消耗的热能很少,织物中水分d2 ≈d1 。因此,称时间间隔t1 为升速烘燥区。当织物温度达到T 2 后,烘燥正式开始。在t 2 这段时间内,给予织物的热量几乎全部用于蒸发织物中的水分,使它从d2降到d3 ,而织物的温度T3 ≈T2 ,时间间隔t2 称为恒速烘燥区。织物的烘燥过程大部分是在这个区域里完成的。随着烘燥过程的继续进行当织物中的水分达到d 3后,接近其临界值,烘燥速度随之降低,织物温度继续上升至T4 ,织物含水率达到其临界值d4 时,烘燥过程中止。时间间隔t3 称为降速烘燥区。因此,烘燥的速度曲线具有梯形特征。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  织物在烘燥过程中的升温是依靠热传导、热对流和热辐射三种基本热交换形式来实现的。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  当高温物体与低温物体直接接触时,热量由高温物体传递到低温物体,或在同一物体中,其中一部分温度较高,另一部分温度较低,热量由高温部分向低温部分传递的物理过程,称为传导传热或热传导。烘筒烘燥机就是利用加热的金属表面与织物表面相接触而传递热量给织物,汽化织物中的水分,从而使之烘干。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  当流体一部分受热时,因其密度的变化而发生流动,从而引起热量的传递,称为对流传热或热对流。由于流体本身各部分密度不同而引起的流动称为“自然对流”。若流体的流动是由于风机等作用而引起的,称为“强制对流”。热风烘燥机、焙烘机及热定形机就是应用加热的空气吹向织物表面而传递热量,从织物中汽化出来的水分,仍由这些热空气带走。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">  以电磁波形式通过空间进行热量传递的过程,称为辐射传热或热辐射。在烘燥机中,一般采用红外线或远红外线等辐射传热。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p></section><section class="_135editor" data-role="paragraph" id="autoparagraph" style="max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; font-family: 微软雅黑, &quot;Microsoft YaHei&quot;, sans-serif; font-size: 17px; caret-color: rgb(255, 0, 0); overflow-wrap: break-word !important; outline: none 0px !important;"></p></section>

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