制冷劑

制(zhi)(zhi)(zhi)(zhi)冷(leng)機(ji)(ji)中完成熱(re)力(li)循環的(de)(de)工(gong)質(zhi)。它在(zai)(zai)(zai)低(di)(di)溫(wen)(wen)下吸(xi)取被冷(leng)卻物(wu)(wu)體的(de)(de)熱(re)量(liang)，然后(hou)在(zai)(zai)(zai)較高溫(wen)(wen)度下轉移給(gei)冷(leng)卻水(shui)或(huo)空氣(qi)(qi)。在(zai)(zai)(zai)蒸(zheng)(zheng)氣(qi)(qi)壓(ya)縮(suo)式(shi)(shi)制(zhi)(zhi)(zhi)(zhi)冷(leng)機(ji)(ji)中，使(shi)用(yong)(yong)(yong)在(zai)(zai)(zai)常溫(wen)(wen)或(huo)較低(di)(di)溫(wen)(wen)度下能(neng)液化(hua)的(de)(de)工(gong)質(zhi)為(wei)制(zhi)(zhi)(zhi)(zhi)冷(leng)劑(ji)，如(ru)氟利昂(ang)（飽和碳氫化(hua)合(he)物(wu)(wu)的(de)(de)氟、氯、溴衍生物(wu)(wu)），共沸混(hun)合(he)工(gong)質(zhi)（由兩種(zhong)氟利昂(ang)按(an)一定(ding)比例混(hun)合(he)而(er)成的(de)(de)共沸溶液）、碳氫化(hua)合(he)物(wu)(wu)（丙烷(wan)、乙烯(xi)等(deng)(deng)）、氨等(deng)(deng)；在(zai)(zai)(zai)氣(qi)(qi)體壓(ya)縮(suo)式(shi)(shi)制(zhi)(zhi)(zhi)(zhi)冷(leng)機(ji)(ji)中，使(shi)用(yong)(yong)(yong)氣(qi)(qi)體制(zhi)(zhi)(zhi)(zhi)冷(leng)劑(ji)，如(ru)空氣(qi)(qi)、氫氣(qi)(qi)、氦氣(qi)(qi)等(deng)(deng)，這些(xie)氣(qi)(qi)體在(zai)(zai)(zai)制(zhi)(zhi)(zhi)(zhi)冷(leng)循環中始終為(wei)氣(qi)(qi)態；在(zai)(zai)(zai)吸(xi)收(shou)式(shi)(shi)制(zhi)(zhi)(zhi)(zhi)冷(leng)機(ji)(ji)中，使(shi)用(yong)(yong)(yong)由吸(xi)收(shou)劑(ji)和制(zhi)(zhi)(zhi)(zhi)冷(leng)劑(ji)組成的(de)(de)二元溶液作為(wei)工(gong)質(zhi)，如(ru)氨和水(shui)、溴化(hua)鋰 （分子式(shi)(shi)：LiBr。白色立(li)方晶系結晶或(huo)粒狀粉末，易溶于(yu)水(shui)）和水(shui)等(deng)(deng)；蒸(zheng)(zheng)汽噴(pen)射式(shi)(shi)制(zhi)(zhi)(zhi)(zhi)冷(leng)機(ji)(ji)用(yong)(yong)(yong)水(shui)作為(wei)制(zhi)(zhi)(zhi)(zhi)冷(leng)劑(ji)。制(zhi)(zhi)(zhi)(zhi)冷(leng)劑(ji)的(de)(de)主要技術(shu)指標有飽和蒸(zheng)(zheng)氣(qi)(qi)壓(ya)強、比熱(re)、粘度、導熱(re)系數、表面(mian)張力(li)等(deng)(deng)。1960年(nian)以后(hou)，人們對(dui)非(fei)共沸混(hun)合(he)工(gong)質(zhi)的(de)(de)應用(yong)(yong)(yong)進行了大量(liang)的(de)(de)試驗研究，并已將(jiang)其用(yong)(yong)(yong)于(yu)天然氣(qi)(qi)的(de)(de)液化(hua)和分離等(deng)(deng)方面(mian)。應用(yong)(yong)(yong)非(fei)共沸混(hun)合(he)工(gong)質(zhi)單級壓(ya)縮(suo)可得到很低(di)(di)的(de)(de)蒸(zheng)(zheng)發溫(wen)(wen)度，且可增加(jia)制(zhi)(zhi)(zhi)(zhi)冷(leng)量(liang)，減少功耗。 它的(de)(de)性質(zhi)直接(jie)關系到制(zhi)(zhi)(zhi)(zhi)冷(leng)裝置的(de)(de)制(zhi)(zhi)(zhi)(zhi)冷(leng)效果(guo)、經(jing)濟性及運行管理，因而(er)對(dui)制(zhi)(zhi)(zhi)(zhi)冷(leng)劑(ji)性質(zhi)要求(qiu)的(de)(de)了解是不容忽視的(de)(de)。