鋁管鋁套冷風機傳熱性能分析
發布時(shi)間：2022-7-8
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近年來有不(bu)少生產廠家在生產鋁(lv)管鋁(lv)套片冷風(feng)機，生產這種(zhong)冷風(feng)機究竟有什么好(hao)處?本文(wen)主要想從傳熱效果的角度(du)來分析探討。
一、鋁管鋁套冷風(feng)機傳熱(re)效果理論(lun)分(fen)析
不能(neng)簡單的(de)(de)認為由于冷(leng)風機(ji)鋁(lv)合(he)金材料的(de)(de)導(dao)熱(re)系(xi)數(shu)(shu)較(jiao)(jiao)(jiao)(jiao)鋼材料大(da)(da)(da)(da)，使金屬壁(bi)熱(re)阻力(li)(li)項減小(xiao)而使傳(chuan)熱(re)系(xi)數(shu)(shu)增大(da)(da)(da)(da)。其實這個因素(su)是(shi)微不足(zu)道的(de)(de)。更重要的(de)(de)原因之(zhi)一(yi)(yi)是(shi)鋁(lv)合(he)金大(da)(da)(da)(da)的(de)(de)導(dao)熱(re)系(xi)數(shu)(shu)大(da)(da)(da)(da)大(da)(da)(da)(da)了翅(chi)片(pian)(pian)效率(lv)，減小(xiao)了空(kong)氣側熱(re)交換的(de)(de)阻力(li)(li)，因此了傳(chuan)熱(re)效率(lv)使傳(chuan)熱(re)系(xi)數(shu)(shu)增大(da)(da)(da)(da)。冷(leng)風機(ji)翅(chi)片(pian)(pian)效率(lv)η＝th(mL)/(mL)［1］，如(ru)果(mL)值(zhi)大(da)(da)(da)(da)時(shi)，當熱(re)量(liang)由翅(chi)片(pian)(pian)基部向端(duan)部傳(chuan)遞時(shi)，翅(chi)片(pian)(pian)端(duan)部過余溫度(du)(du)較(jiao)(jiao)(jiao)(jiao)小(xiao)，這表明翅(chi)片(pian)(pian)表面(mian)平均溫度(du)(du)較(jiao)(jiao)(jiao)(jiao)低(di)，翅(chi)片(pian)(pian)的(de)(de)效率(lv)也效低(di)。反之(zhi)，如(ru)果(mL)值(zhi)較(jiao)(jiao)(jiao)(jiao)小(xiao)時(shi)，翅(chi)片(pian)(pian)效率(lv)較(jiao)(jiao)(jiao)(jiao)高(gao)。因此，在一(yi)(yi)定翅(chi)片(pian)(pian)高(gao)度(du)(du)(L)條件下，m值(zhi)較(jiao)(jiao)(jiao)(jiao)小(xiao)是(shi)有(you)(you)利的(de)(de)。選用(yong)導(dao)熱(re)系(xi)數(shu)(shu)大(da)(da)(da)(da)的(de)(de)材料，正好(hao)能(neng)使m值(zhi)減小(xiao)。所以選用(yong)鋁(lv)管鋁(lv)片(pian)(pian)較(jiao)(jiao)(jiao)(jiao)之(zhi)鋼管鋼片(pian)(pian)更有(you)(you)利于冷(leng)風機(ji)傳(chuan)熱(re)效果使傳(chuan)熱(re)系(xi)數(shu)(shu)增大(da)(da)(da)(da)。
例如(ru)有下列翅(chi)(chi)片(pian)(pian)(pian)(pian)盤管(guan)(guan)(guan)(guan)(guan)結構(gou)的(de)(de)(de)冷風(feng)機：管(guan)(guan)(guan)(guan)(guan)子Φ20×1.0，等邊(bian)三角形(xing)叉排，管(guan)(guan)(guan)(guan)(guan)子間距60mm，管(guan)(guan)(guan)(guan)(guan)子排距52mm，采用整(zheng)體式平翅(chi)(chi)片(pian)(pian)(pian)(pian)，翅(chi)(chi)片(pian)(pian)(pian)(pian)厚0.23mm，翅(chi)(chi)片(pian)(pian)(pian)(pian)間距12mm。如(ru)果翅(chi)(chi)片(pian)(pian)(pian)(pian)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)材料采用鋼管(guan)(guan)(guan)(guan)(guan)鋼片(pian)(pian)(pian)(pian)或(huo)鋁管(guan)(guan)(guan)(guan)(guan)鋁片(pian)(pian)(pian)(pian)，我們(men)根據(ju)文獻［2］提供的(de)(de)(de)方(fang)法作計(ji)算比較(jiao)。假設："冷風(feng)機在無(wu)霜工況下運行；蒸發溫度為-20℃；據(ju)某次實(shi)際測定(ding)，迎面風(feng)速為2.8m/s、進風(feng)溫度-6℃、進風(feng)相對濕度63%；計(ji)算可得制冷劑側放熱系數為500W/(m２•K)［2］"。計(ji)算結果如(ru)下，翅(chi)(chi)片(pian)(pian)(pian)(pian)效率：鋼管(guan)(guan)(guan)(guan)(guan)鋼片(pian)(pian)(pian)(pian)為0.35；鋁管(guan)(guan)(guan)(guan)(guan)鋁片(pian)(pian)(pian)(pian)為0.58。翅(chi)(chi)片(pian)(pian)(pian)(pian)管(guan)(guan)(guan)(guan)(guan)總效率：鋼管(guan)(guan)(guan)(guan)(guan)鋼片(pian)(pian)(pian)(pian)為0.43；鋁管(guan)(guan)(guan)(guan)(guan)鋁片(pian)(pian)(pian)(pian)0.63。對傳熱系數的(de)(de)(de)影響(xiang)；在上(shang)述相同(tong)條件下，鋁管(guan)(guan)(guan)(guan)(guan)鋁片(pian)(pian)(pian)(pian)冷風(feng)機的(de)(de)(de)傳熱系數比鋼管(guan)(guan)(guan)(guan)(guan)鋼片(pian)(pian)(pian)(pian)的(de)(de)(de)高(gao)出27.8%。
二、冷(leng)風機(ji)傳熱性(xing)能(neng)結(jie)果
我們可(ke)以從冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)傳(chuan)(chuan)熱(re)系(xi)數k與單位面積冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)熱(re)負荷Q來進(jin)行分析，比(bi)較(jiao)(jiao)的條件(jian)是，冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)基(ji)本上是在(zai)無(wu)霜條件(jian)下運行。以某生產廠家生產的結(jie)(jie)構相同，冷(leng)(leng)卻面積、配風(feng)(feng)(feng)量相似(si)的冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)作比(bi)較(jiao)(jiao)，通過低溫(wen)試(shi)驗室實際測試(shi)的結(jie)(jie)果(guo)，冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)的傳(chuan)(chuan)熱(re)系(xi)數。蒸(zheng)發(fa)溫(wen)度(du)-10℃時，鋁(lv)管(guan)鋁(lv)片冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)的傳(chuan)(chuan)熱(re)系(xi)數比(bi)鋼(gang)管(guan)鋼(gang)片冷(leng)(leng)風(feng)(feng)(feng)機(ji)(ji)高出約(yue)20～35%，顯示(shi)了鋁(lv)管(guan)鋁(lv)片的優(you)勢。但隨著蒸(zheng)發(fa)溫(wen)度(du)，這(zhe)種優(you)勢趨小(xiao)。在(zai)實際中還(huan)發(fa)現，當翅片管(guan)結(jie)(jie)霜后，并未顯示(shi)這(zhe)種優(you)勢。
但是(shi)，由于生產工藝、制造水平(ping)及冷(leng)(leng)風機結構(gou)的差(cha)異，不(bu)同廠生產的冷(leng)(leng)風機，其傳熱系(xi)數的差(cha)別也(ye)較大。
另一(yi)(yi)方(fang)面(mian)，從單位面(mian)積熱負(fu)荷來看，對同一(yi)(yi)廠(chang)(chang)生(sheng)(sheng)產(chan)的(de)(de)結(jie)構(gou)類同、冷卻(que)面(mian)積、配(pei)風量(liang)相似的(de)(de)冷風機(ji)(ji)，通過(guo)低(di)溫試(shi)驗室(shi)進行性能測定的(de)(de)實際結(jie)果表(biao)明："鋁(lv)管鋁(lv)片(pian)(pian)冷風機(ji)(ji)的(de)(de)Q值比(bi)(bi)鋼(gang)管鋼(gang)片(pian)(pian)冷風機(ji)(ji)的(de)(de)Q值高(gao)(gao)出(chu)(chu)約40%左右"。但是，產(chan)品(pin)生(sheng)(sheng)產(chan)質量(liang)水平(ping)較低(di)廠(chang)(chang)家(jia)生(sheng)(sheng)產(chan)的(de)(de)鋁(lv)管鋁(lv)片(pian)(pian)冷風機(ji)(ji)Q值僅(jin)比(bi)(bi)鋼(gang)管鋼(gang)片(pian)(pian)冷風機(ji)(ji)Q值高(gao)(gao)出(chu)(chu)大(da)約為14～27%。我們(men)從某生(sheng)(sheng)產(chan)水平(ping)比(bi)(bi)較高(gao)(gao)的(de)(de)廠(chang)(chang)提供的(de)(de)產(chan)品(pin)樣本數(shu)據，對結(jie)構(gou)類同、冷卻(que)面(mian)積、配(pei)風量(liang)相似的(de)(de)冷風機(ji)(ji)產(chan)品(pin)作比(bi)(bi)較可以(yi)得(de)到(dao)："每平(ping)方(fang)米冷卻(que)面(mian)積的(de)(de)熱負(fu)荷Q(kW/m2)，鋁(lv)管鋁(lv)片(pian)(pian)比(bi)(bi)鋼(gang)管鋼(gang)片(pian)(pian)的(de)(de)值高(gao)(gao)出(chu)(chu)約18～43%"。這(zhe)一(yi)(yi)數(shu)值與低(di)溫試(shi)驗室(shi)實際測定結(jie)果相當吻合。
結論(lun)：從(cong)傳(chuan)(chuan)熱效(xiao)果(guo)分析(xi)可見(jian)，用(yong)導熱系數大的材(cai)料制作冷風機的翅片(pian)盤管(guan)，在相同(tong)結構參數條件(jian)下可以得(de)到較好(hao)的傳(chuan)(chuan)熱效(xiao)果(guo)。
