制冷劑

制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)機(ji)(ji)(ji)中(zhong)(zhong)完成(cheng)熱力循環的(de)(de)工(gong)質(zhi)(zhi)。它在(zai)(zai)(zai)低溫下(xia)(xia)吸(xi)取被冷(leng)(leng)(leng)(leng)(leng)(leng)卻物體(ti)(ti)的(de)(de)熱量，然后在(zai)(zai)(zai)較高(gao)溫度(du)(du)(du)下(xia)(xia)轉移給冷(leng)(leng)(leng)(leng)(leng)(leng)卻水(shui)(shui)(shui)或空(kong)氣(qi)。在(zai)(zai)(zai)蒸(zheng)氣(qi)壓(ya)縮式(shi)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)機(ji)(ji)(ji)中(zhong)(zhong)，使用(yong)(yong)在(zai)(zai)(zai)常溫或較低溫度(du)(du)(du)下(xia)(xia)能液化的(de)(de)工(gong)質(zhi)(zhi)為(wei)(wei)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)劑(ji)，如氟(fu)(fu)(fu)利昂（飽和(he)(he)碳(tan)氫化合(he)物的(de)(de)氟(fu)(fu)(fu)、氯、溴衍生物），共(gong)(gong)(gong)沸(fei)混合(he)工(gong)質(zhi)(zhi)（由兩種氟(fu)(fu)(fu)利昂按一定比(bi)例(li)混合(he)而成(cheng)的(de)(de)共(gong)(gong)(gong)沸(fei)溶液）、碳(tan)氫化合(he)物（丙烷、乙烯等）、氨等；在(zai)(zai)(zai)氣(qi)體(ti)(ti)壓(ya)縮式(shi)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)機(ji)(ji)(ji)中(zhong)(zhong)，使用(yong)(yong)氣(qi)體(ti)(ti)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)劑(ji)，如空(kong)氣(qi)、氫氣(qi)、氦(hai)氣(qi)等，這些氣(qi)體(ti)(ti)在(zai)(zai)(zai)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)循環中(zhong)(zhong)始終為(wei)(wei)氣(qi)態(tai)；在(zai)(zai)(zai)吸(xi)收式(shi)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)機(ji)(ji)(ji)中(zhong)(zhong)，使用(yong)(yong)由吸(xi)收劑(ji)和(he)(he)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)劑(ji)組成(cheng)的(de)(de)二元(yuan)溶液作為(wei)(wei)工(gong)質(zhi)(zhi)，如氨和(he)(he)水(shui)(shui)(shui)、溴化鋰 （分(fen)(fen)子式(shi)：LiBr。白色立方晶系(xi)結晶或粒狀粉末，易溶于(yu)水(shui)(shui)(shui)）和(he)(he)水(shui)(shui)(shui)等；蒸(zheng)汽(qi)噴射(she)式(shi)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)機(ji)(ji)(ji)用(yong)(yong)水(shui)(shui)(shui)作為(wei)(wei)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)劑(ji)。制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)劑(ji)的(de)(de)主要技術指標有飽和(he)(he)蒸(zheng)氣(qi)壓(ya)強(qiang)、比(bi)熱、粘度(du)(du)(du)、導熱系(xi)數、表面(mian)張力等。1960年以后，人們對非(fei)共(gong)(gong)(gong)沸(fei)混合(he)工(gong)質(zhi)(zhi)的(de)(de)應用(yong)(yong)進行(xing)了大量的(de)(de)試驗研究，并已將其用(yong)(yong)于(yu)天(tian)然氣(qi)的(de)(de)液化和(he)(he)分(fen)(fen)離等方面(mian)。應用(yong)(yong)非(fei)共(gong)(gong)(gong)沸(fei)混合(he)工(gong)質(zhi)(zhi)單級壓(ya)縮可得到(dao)很低的(de)(de)蒸(zheng)發溫度(du)(du)(du)，且可增加(jia)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)量，減少功耗。 它的(de)(de)性(xing)質(zhi)(zhi)直接關(guan)系(xi)到(dao)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)裝置的(de)(de)制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)效果、經濟性(xing)及運行(xing)管理，因而對制(zhi)冷(leng)(leng)(leng)(leng)(leng)(leng)劑(ji)性(xing)質(zhi)(zhi)要求(qiu)的(de)(de)了解(jie)是不容忽視的(de)(de)。