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| 高低溫試驗箱復疊式冷凍機技術知識介紹 |
| 來源：諾冰制冷 發布時間：2016-8-15 |
高低(di)溫(wen)(wen)(wen)(wen)試驗箱(xiang)復疊式冷(leng)凍機(ji)通常由兩個部(bu)(bu)(bu)分(fen)(也可由三(san)個部(bu)(bu)(bu)分(fen)) 組成，分(fen)別稱為高溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)及低(di)溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)。高溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)使(shi)用(yong)中溫(wen)(wen)(wen)(wen)制冷(leng)劑(ji)，低(di)溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)使(shi)用(yong)低(di)溫(wen)(wen)(wen)(wen)制冷(leng)劑(ji)，而每一(yi)部(bu)(bu)(bu)分(fen)都是(shi)一(yi)個完整的單級(ji)或雙級(ji)壓縮制冷(leng)系(xi)(xi)統(tong)。高溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)系(xi)(xi)統(tong)中制冷(leng)劑(ji)的蒸發(fa)是(shi)用(yong)來(lai)使(shi)低(di)溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)系(xi)(xi)統(tong)中制冷(leng)劑(ji)冷(leng)凝(ning)(ning)，而只有(you)低(di)溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)系(xi)(xi)統(tong)的制冷(leng)劑(ji)在蒸發(fa)時才制取(qu)冷(leng)量。高溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)和低(di)溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)用(yong)一(yi)個冷(leng)凝(ning)(ning)蒸發(fa)器(qi)聯系(xi)(xi)起來(lai),它既(ji)是(shi)高溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)的蒸發(fa)器(qi),又(you)是(shi)低(di)溫(wen)(wen)(wen)(wen)部(bu)(bu)(bu)分(fen)的冷(leng)凝(ning)(ning)器(qi)。高低(di)溫(wen)(wen)(wen)(wen)試驗箱(xiang)復疊制冷(leng)機(ji)組大都以R22/ R404為制冷(leng)劑(ji)。
高低(di)溫試驗箱復疊式(shi)冷凍機有兩個比較(jiao)重要的知識點：
一、中間(jian)溫度(du)的確(que)定(ding)
復疊式制冷循環中(zhong)中(zhong)間溫(wen)度的確定(ding)應根據制冷系數最大或各個壓縮機壓力(li)(li)比大致(zhi)相等的原則(ze)。前者(zhe)對能量(liang)利用最經濟,后者(zhe)對壓縮機氣(qi)缸(gang)工作容積的利用率較(jiao)高(gao)(即輸氣(qi)系數較(jiao)大) 。由于(yu)中(zhong)間溫(wen)度在(zai)一定(ding)范圍內(nei)變動時對制泠系數影響(xiang)并不大,故按各級(ji)壓力(li)(li)比大致(zhi)相等的原則(ze)來確定(ding)中(zhong)間溫(wen)度似乎(hu)更為合理。
二、膨脹容器
高低溫試驗箱復疊式冷凍機停止運轉時,由于系統內的溫度升高到了環境溫度，低溫制冷劑全部氣化成過熱蒸汽，并且將高于規定的最大工作壓力，這種情況是不允許的。因此要在系統中接入一個膨脹容器，以便在停機后大部分的制冷劑蒸汽進入膨脹容器中，膨脹容器可以接到吸氣管上，也可以接到排氣管上，接到吸氣管上時，膨脹容器所需要的容積較小，因而比較合理 。
膨脹容器的容積(ji)可按如下方法計(ji)算:
V p = ( Gd*vp - V d)*vd/(vd – vp)
式(shi)中: V d 為(wei)不計(ji)膨(peng)脹(zhang)容(rong)(rong)(rong)器容(rong)(rong)(rong)積(ji)(ji)時，低溫部分(fen)的制(zhi)冷(leng)系(xi)統(tong)總容(rong)(rong)(rong)積(ji)(ji)(m3) ; vp 為(wei)設(she)計(ji)溫度、設(she)計(ji)壓(ya)力(li)下低溫系(xi)統(tong)制(zhi)冷(leng)劑過熱(re)(re)氣體(ti)(ti)比容(rong)(rong)(rong)(m3/ kg) ; v d 為(wei)設(she)計(ji)溫度、吸氣壓(ya)力(li)下低溫系(xi)統(tong)制(zhi)冷(leng)劑過熱(re)(re)氣體(ti)(ti)比容(rong)(rong)(rong)(m3/ kg) ; Gd 為(wei)不計(ji)膨(peng)脹(zhang)容(rong)(rong)(rong)器容(rong)(rong)(rong)積(ji)(ji)時,低溫系(xi)統(tong)制(zhi)冷(leng)劑充注(zhu)量(kg) 。(end) |
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