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为什么二氧化碳在蓄冷器(或切换式换热器)中的析出温度要比大气压力下二氧化碳的凝固温度低得多?

   2021-01-10 中国天然气网佚名383
核心提示：为什么二氧化碳在蓄冷器(或切换式换热器)中的析出温度要比大气压力下二氧化碳的凝固温度低得多? 答：二氧化碳的
 
为什么二氧化碳在蓄冷器(或切换式换热器)中的析出温度要比大气压力下二氧化碳的凝固温度低得多?
 
    答：二氧化碳的凝结(或凝固)温度和其他气体一样，也是随着压力的降低而降低，如表22、表23所示。
normal style="TEXT-INDENT: 18pt; LINE-HEIGHT: 150%">表22二氧化碳凝固温度与压力的关系
normal style="TEXT-INDENT: 18pt; LINE-HEIGHT: 150%"> 

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>压力/Pa

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>1×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>2×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>3×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>4×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>5×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>凝固温度/℃

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-78.2

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-70.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-64.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-61

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-58

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-layout-grid-align: none" align=left> 
表23二氧化碳液化(凝结)温度与压力的关系
 

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>压力/Pa

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>5.28×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>8×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>15×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>20×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>30×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>40×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>50×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>60×105

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>液化温度/℃

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-56.6

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-46.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-29

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-20

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>-5.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>5.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>14.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center" align=center>21.5

normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-layout-grid-align: none" align=left> 
    二氧化碳三相点压力为0.528MPa、温度为-56.6℃。二氧化碳压力低于0.528MPa时，温度降至凝固温度、由气相直接变为固相；而压力高于0.528MPa时，温度降至液化温度，二氧化碳凝结为液体。
    由表可见，纯二氧化碳的压力为0.1MPa时，其凝固温度为-78.2℃。空气通过切换式换热器时，虽然其压力在0.6MPa左右，但空气的压力并不是二氧化碳的压力。空气中二氧化碳的分压力与其在空气中的含量成正比。空气中二氧化碳的体积含量一般为300～400× 10-6(体积分数为0.03%～0.04%)，空气压力为0.6MPa时，二氧化碳的分压力只不过是180℃400Pa，相应的凝固温度为-132～-135℃。
normal style="TEXT-INDENT: 18pt; LINE-HEIGHT: 150%; tab-stops: 99.75pt">由于二氧化碳的分压力大大低于0.1MPa，所以其凝固温度要比-78.2℃低得多。在切换式换热器中，随着二氧化碳的被冻结，空气中二氧化碳的分压力在降低，其凝固温度也随着降低，如表24所示。二氧化碳的实际凝结温度比表中所列温度还要低一些。
normal style="TEXT-INDENT: 18pt; LINE-HEIGHT: 150%; tab-stops: 99.75pt"> 
normal style="LINE-HEIGHT: 150%; tab-stops: 99.75pt">表24二氧化碳凝固温度与空气压力及其中所含二氧化碳量的关系
normal style="LINE-HEIGHT: 150%; tab-stops: 99.75pt"> 
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>凝固温度/℃
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>二氧化碳含量
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>400
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>300
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>100
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>50
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>20
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>10
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>2
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>1
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>压力
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>0.1
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>MPa
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-142×
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-143.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>  ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-149.2
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center> ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-152.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center> ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-156
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center> ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-159.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-162×
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-165.6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center> ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-168×
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>0.6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>MPa
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-132×
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-133.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center> ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-140.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-143.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-148.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-151.7
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-154.7
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-158.5
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center> ×10-6
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>-161.2
normal style="LINE-HEIGHT: 150%; TEXT-ALIGN: center; tab-stops: 99.75pt" align=center>×10-6
 
 
为什么二氧化碳在蓄冷器(或切换式换热器)中的析出温度要比大气压力下二氧化碳的凝固温度低得多?
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