1、引言

    隨著(zhu)人(ren)類社會的進步和(he)生產(chan)(chan)需(xu)要，制冷工業迅速發展，低溫制冷技術在醫療(liao)、機(ji)械(xie)、化工、石油、電子(zi)、航天(tian)(tian)、軍(jun)工等(deng)領域的應用也日益(yi)廣泛。其(qi)中(zhong)，為(wei)了檢測和(he)分析儀器、儀表、機(ji)械(xie)、電子(zi)等(deng)樣品(pin)材料及(ji)(ji)零部件承受老化以(yi)(yi)及(ji)(ji)熱脹冷縮(suo)等(deng)性能(neng)，需(xu)要模擬(ni)出溫濕度恒(heng)定(ding)或漸變以(yi)(yi)及(ji)(ji)冷熱沖擊等(deng)不同的試驗環境，以(yi)(yi)便篩選(xuan)出產(chan)(chan)品(pin)設(she)計和(he)工藝上的缺陷，為(wei)設(she)計定(ding)型和(he)批產(chan)(chan)驗收決(jue)策提供依據。因(yin)此，溫濕度環境試驗設(she)備得到了航天(tian)(tian)航空(kong)、車輛工程(cheng)以(yi)(yi)及(ji)(ji)電工電子(zi)等(deng)行業越來越多(duo)的關注(zhu)。
    為了搭建高低溫沖擊試驗箱實驗平臺，首先需要設計出能夠模擬-40℃~ - 70℃低溫環境的制冷系統。復疊制冷是此溫度范圍的重要制冷方式，其由高溫制冷循環和低溫制冷循環構成，高溫制冷循環產生的冷量用來在蒸發冷凝器中冷凝低溫制冷循環的制冷劑，冷凝后的低溫級制冷劑經過節流閥進人蒸發器蒸發從而降低環境溫度。復疊制冷在-40~-120℃范圍內有著良好的制冷效果。本文采用復疊式制冷和電加熱控制技術，搭建了高低溫環境冷熱沖擊試驗箱，對高低溫沖擊試驗箱的性能進行了實驗研究。

    2、制冷(leng)工質(zhi)的選擇

    復(fu)疊(die)式制冷(leng)(leng)系統需要(yao)選擇兩種(zhong)類(lei)型(xing)的制冷(leng)(leng)劑(ji)，即中(zhong)溫制冷(leng)(leng)劑(ji)和(he)低(di)溫制冷(leng)(leng)劑(ji)。由(you)于國際社會對環境安全的日益(yi)重視，此前廣泛(fan)使用的R13、R22等CFC、HCFC類(lei)型(xing)的制冷(leng)(leng)劑(ji)已逐(zhu)步被代替(ti)。鑒于R23和(he)R404A的ODP為零(ling)，安全性(xing)(xing)好(hao)(hao)，是環境友好(hao)(hao)型(xing)制冷(leng)(leng)劑(ji)，因此在綜合考慮制冷(leng)(leng)劑(ji)的制冷(leng)(leng)性(xing)(xing)能(neng)、壓縮(suo)機(ji)工(gong)作(zuo)的可靠(kao)性(xing)(xing)和(he)環境友好(hao)(hao)性(xing)(xing)后，選擇R404A/R23作(zuo)為復(fu)疊(die)式制冷(leng)(leng)系統的制冷(leng)(leng)劑(ji)， R404A 和(he)R23的性(xing)(xing)能(neng)參數(shu)(shu)見表1。其中(zhong)，R404A由(you)R125( 標(biao)準(zhun)沸點(dian)- 49℃)、R143a(標(biao)準(zhun)沸點(dian)-47.2℃)和(he)R134a(標(biao)準(zhun)沸點(dian)-26.1℃)按質(zhi)量分(fen)數(shu)(shu)44:52:4混合而(er)成，具有與(yu)R22(標(biao)準(zhun)沸點(dian)-40.8℃ )較為相近的熱(re)物理(li)性(xing)(xing)質(zhi)。

    3、實(shi)驗裝置與實(shi)驗

    圖(tu)1為(wei)(wei)高低(di)(di)溫(wen)(wen)(wen)(wen)沖擊(ji)試(shi)(shi)驗(yan)箱(xiang)(xiang)(xiang)實驗(yan)裝(zhuang)置(zhi)系(xi)統(tong)圖(tu)。試(shi)(shi)驗(yan)箱(xiang)(xiang)(xiang)本體主要(yao)包括高溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)和(he)(he)(he)低(di)(di)溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)。低(di)(di)溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)內(nei)的復疊制冷(leng)(leng)(leng)系(xi)統(tong)由(you)高溫(wen)(wen)(wen)(wen)制冷(leng)(leng)(leng)循(xun)環(huan)(huan)和(he)(he)(he)低(di)(di)溫(wen)(wen)(wen)(wen)制冷(leng)(leng)(leng)循(xun)環(huan)(huan)組成，設備主要(yao)有(you)壓(ya)縮(suo)(suo)機(ji)、冷(leng)(leng)(leng)凝器(qi)(qi)(qi)、膨脹閥(或毛細(xi)管(guan))、蒸(zheng)發冷(leng)(leng)(leng)凝器(qi)(qi)(qi)、蒸(zheng)發器(qi)(qi)(qi)、油分離器(qi)(qi)(qi)，干燥過濾器(qi)(qi)(qi)等，兩(liang)(liang)個(ge)(ge)制冷(leng)(leng)(leng)循(xun)環(huan)(huan)通(tong)過蒸(zheng)發冷(leng)(leng)(leng)凝器(qi)(qi)(qi)相結合。高、低(di)(di)溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)內(nei)部(bu)結構相似:幾(ji)何尺寸均(jun)為(wei)(wei)650mmx650mmx600mm，每個(ge)(ge)箱(xiang)(xiang)(xiang)體.上部(bu)都有(you)兩(liang)(liang)個(ge)(ge)百葉進(jin)風(feng)口(kou)，下部(bu)有(you)兩(liang)(liang)個(ge)(ge)百葉出風(feng)口(kou)，風(feng)口(kou)裝(zhuang)有(you)兩(liang)(liang)個(ge)(ge)循(xun)環(huan)(huan)風(feng)機(ji)，且裝(zhuang)有(you)電(dian)(dian)加熱盤管(guan)調節溫(wen)(wen)(wen)(wen)度(du)(du)。當風(feng)機(ji)工作(zuo)時(shi)，受迫循(xun)環(huan)(huan)空氣經(jing)過熱盤管(guan)、蒸(zheng)發器(qi)(qi)(qi)調節高低(di)(di)溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)內(nei)的溫(wen)(wen)(wen)(wen)度(du)(du)到達目標值(zhi)。測(ce)試(shi)(shi)箱(xiang)(xiang)(xiang)內(nei)部(bu)尺寸為(wei)(wei)500mm x 500mm x 500mm ，容(rong)積為(wei)(wei)125L，通(tong)過氣缸的運動快速拉(la)動測(ce)試(shi)(shi)箱(xiang)(xiang)(xiang)，分別在(zai)高、低(di)(di)溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)中進(jin)行(xing)冷(leng)(leng)(leng)熱沖擊(ji)試(shi)(shi)驗(yan)，氣缸由(you)空壓(ya)機(ji)的壓(ya)縮(suo)(suo)空氣提供動力。為(wei)(wei)了研究測(ce)試(shi)(shi)箱(xiang)(xiang)(xiang)內(nei)的溫(wen)(wen)(wen)(wen)度(du)(du)均(jun)勻度(du)(du)，在(zai)測(ce)試(shi)(shi)箱(xiang)(xiang)(xiang)內(nei)布(bu)置(zhi)了9個(ge)(ge)T型熱電(dian)(dian)偶(ou)作(zuo)為(wei)(wei)溫(wen)(wen)(wen)(wen)度(du)(du)測(ce)試(shi)(shi)點。在(zai)高、低(di)(di)溫(wen)(wen)(wen)(wen)循(xun)環(huan)(huan)壓(ya)縮(suo)(suo)機(ji)的進(jin)、出口(kou)布(bu)置(zhi)壓(ya)力測(ce)試(shi)(shi)點，研究壓(ya)縮(suo)(suo)機(ji)的工作(zuo)狀況。高、低(di)(di)溫(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)內(nei)都裝(zhuang)有(you)三線制PT100溫(wen)(wen)(wen)(wen)度(du)(du)傳感器(qi)(qi)(qi)，精(jing)度(du)(du)為(wei)(wei)±0. 1℃，數(shu)據(ju)同步輸(shu)人(ren)UMC1000控制器(qi)(qi)(qi)中，控制制冷(leng)(leng)(leng)系(xi)統(tong)和(he)(he)(he)加熱系(xi)統(tong)工作(zuo)狀況。

    4、實驗研究(jiu)

    實(shi)驗(yan)(yan)選取兩(liang)組沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)進(jin)(jin)行測(ce)(ce)試(shi)，分別(bie)(bie)用實(shi)驗(yan)(yan)1和(he)(he)(he)實(shi)驗(yan)(yan)2表示。實(shi)驗(yan)(yan)1:沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)為- 55℃和(he)(he)(he)200℃ ;實(shi)驗(yan)(yan)2:沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)為-45℃和(he)(he)(he)150℃。測(ce)(ce)試(shi)箱(xiang)(xiang)(xiang)(xiang)由高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)到(dao)低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)時，高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)的(de)(de)預熱(re)(re)(re)、預冷(leng)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)分別(bie)(bie)為200℃、- 70 ℃(實(shi)驗(yan)(yan)1)和(he)(he)(he)150℃、-60℃(實(shi)驗(yan)(yan)2);測(ce)(ce)試(shi)箱(xiang)(xiang)(xiang)(xiang)由低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)到(dao)高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)時，高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)的(de)(de)預熱(re)(re)(re)、預冷(leng)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)分別(bie)(bie)為210℃、-55℃(實(shi)驗(yan)(yan)1)和(he)(he)(he)160℃、-45℃(實(shi)驗(yan)(yan)2)。實(shi)驗(yan)(yan)前使(shi)用真空泵(beng)將高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)制(zhi)冷(leng)循(xun)環(huan)系統(tong)抽真空后(hou)，再將選擇的(de)(de)制(zhi)冷(leng)劑R404A和(he)(he)(he)R23分別(bie)(bie)充人到(dao)高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)制(zhi)冷(leng)循(xun)環(huan)系統(tong)內(nei)，并(bing)用電(dian)子稱測(ce)(ce)出制(zhi)冷(leng)劑的(de)(de)充人量。經過調試(shi)，制(zhi)冷(leng)系統(tong)工(gong)作(zuo)正(zheng)常。電(dian)源接(jie)通(tong)后(hou)，高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)區(qu)內(nei)的(de)(de)電(dian)加熱(re)(re)(re)管立即工(gong)作(zuo)，通(tong)過PID調節(jie)將高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)環(huan)境預熱(re)(re)(re)到(dao)目(mu)標溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)。為確保壓縮機安全工(gong)作(zuo)，防止(zhi)誤操作(zuo)，電(dian)源接(jie)通(tong)后(hou)30s，高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)級(ji)(ji)壓縮機啟動(dong)，當高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)級(ji)(ji)蒸(zheng)發溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)達到(dao)低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)級(ji)(ji)冷(leng)凝溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)時，低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)級(ji)(ji)壓縮機再啟動(dong)。低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)級(ji)(ji)制(zhi)冷(leng)劑進(jin)(jin)人蒸(zheng)發器將低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)環(huan)境預冷(leng)到(dao)目(mu)標溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)，同時低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)內(nei)電(dian)加熱(re)(re)(re)盤管在PID調節(jie)下(xia)(xia)工(gong)作(zuo)，使(shi)低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)內(nei)穩(wen)定(ding)后(hou)的(de)(de)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)波動(dong)范圍控(kong)制(zhi)在±0.5℃。當高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)達到(dao)預熱(re)(re)(re)、預冷(leng)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)并(bing)穩(wen)定(ding)后(hou)，測(ce)(ce)試(shi)箱(xiang)(xiang)(xiang)(xiang)在氣(qi)(qi)缸的(de)(de)拉動(dong)下(xia)(xia)瞬間(jian)(jian)從高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)到(dao)低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)(或低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)到(dao)高(gao)(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)) ， 測(ce)(ce)試(shi)箱(xiang)(xiang)(xiang)(xiang)內(nei)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)迅速變化，終穩(wen)定(ding)在沖(chong)(chong)(chong)(chong)擊(ji)(ji)(ji)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)設定(ding)值(zhi)(zhi)。在這期(qi)間(jian)(jian)，記錄(lu)下(xia)(xia)壓縮機進(jin)(jin)、排氣(qi)(qi)口壓力和(he)(he)(he)高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)(xiang)(xiang)(xiang)內(nei)的(de)(de)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)(du)隨時間(jian)(jian)變化的(de)(de)值(zhi)(zhi)。

    5、結(jie)果與(yu)討論

    圖2與圖3分別為(wei)(wei)(wei)實(shi)驗1復疊式制冷(leng)系(xi)統運行過(guo)程中高(gao)(gao)、低(di)(di)(di)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)進、排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)隨時(shi)間(jian)(jian)變(bian)(bian)化曲線(xian)。圖2和(he)圖3表明，低(di)(di)(di)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)在(zai)高(gao)(gao)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)運行60s后(hou)(hou)開始工作，兩級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)隨時(shi)間(jian)(jian)變(bian)(bian)化趨勢相(xiang)似。在(zai)整(zheng)個沖擊循環過(guo)程中，高(gao)(gao)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)的進氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)谷值(zhi)和(he)排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)峰值(zhi)出(chu)現的時(shi)間(jian)(jian)均早于(yu)低(di)(di)(di)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)，且壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)值(zhi)先達到穩(wen)(wen)(wen)定(ding)(ding)(ding)。從圖2中可(ke)看出(chu)，高(gao)(gao)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)穩(wen)(wen)(wen)定(ding)(ding)(ding)后(hou)(hou)的排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)約(yue)為(wei)(wei)(wei)1. 1MPa，進氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)約(yue)為(wei)(wei)(wei)0. 2MPa，壓(ya)(ya)(ya)(ya)(ya)(ya)比約(yue)為(wei)(wei)(wei)5.5。從圖3中可(ke)以看出(chu)，在(zai)預冷(leng)階(jie)段(duan)(duan)(O31A31和(he)O32A32段(duan)(duan)) ，低(di)(di)(di)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)的排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)上(shang)升后(hou)(hou)緩慢(man)下降(jiang)到穩(wen)(wen)(wen)定(ding)(ding)(ding)值(zhi)，約(yue)為(wei)(wei)(wei)0. 9MPa;進氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)下降(jiang)后(hou)(hou)上(shang)升到穩(wen)(wen)(wen)定(ding)(ding)(ding)值(zhi)，約(yue)為(wei)(wei)(wei)0.1MPa，穩(wen)(wen)(wen)定(ding)(ding)(ding)后(hou)(hou)的壓(ya)(ya)(ya)(ya)(ya)(ya)比約(yue)為(wei)(wei)(wei)9。在(zai)- 55℃沖擊階(jie)段(duan)(duan)( A31B31段(duan)(duan))，由于(yu)低(di)(di)(di)溫(wen)(wen)箱(xiang)內(nei)的溫(wen)(wen)度(du)從- 70℃.上(shang)升到-55℃，與蒸(zheng)發溫(wen)(wen)度(du)相(xiang)對應(ying)，低(di)(di)(di)溫(wen)(wen)級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)也從0.9MPa上(shang)升到穩(wen)(wen)(wen)定(ding)(ding)(ding)值(zhi)，約(yue)為(wei)(wei)(wei)1MPa。在(zai)200心沖擊階(jie)段(duan)(duan)(B31C31段(duan)(duan)) ，低(di)(di)(di)溫(wen)(wen)箱(xiang)內(nei)溫(wen)(wen)度(du)恢(hui)復到- 70℃ ，排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)再次(ci)穩(wen)(wen)(wen)定(ding)(ding)(ding)到0. 9MPa。實(shi)驗2的兩級(ji)壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)進、排(pai)(pai)(pai)氣(qi)(qi)(qi)壓(ya)(ya)(ya)(ya)(ya)(ya)力(li)(li)隨時(shi)間(jian)(jian)變(bian)(bian)化曲線(xian)與實(shi)驗1基本相(xiang)同(tong)。實(shi)驗結果說(shuo)明在(zai)高(gao)(gao)低(di)(di)(di)溫(wen)(wen)沖擊實(shi)驗過(guo)程中壓(ya)(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)運行穩(wen)(wen)(wen)定(ding)(ding)(ding)。

    圖(tu)(tu)4和圖(tu)(tu)5分別表示在整個(ge)沖擊循環試驗過程中高、低(di)溫(wen)(wen)箱(xiang)內環境溫(wen)(wen)度(du)(du)隨時間的變化曲線(xian)。圖(tu)(tu)4表明(ming)，在實(shi)驗的預熱(re)段(O41A41或O42A42段)，高溫(wen)(wen)箱(xiang)溫(wen)(wen)度(du)(du)在電(dian)源啟動后迅(xun)速(su)上升(sheng)，隨著(zhu)溫(wen)(wen)度(du)(du)接(jie)近(jin)預熱(re)溫(wen)(wen)度(du)(du)，電(dian)加(jia)熱(re)管輸(shu)出功率(lv)減小、溫(wen)(wen)升(sheng)速(su)率(lv)降低(di)，箱(xiang)內溫(wen)(wen)度(du)(du)逐近(jin)穩定。實(shi)驗1經過770s(約12. 8min) ，高溫(wen)(wen)箱(xiang)從室溫(wen)(wen)(13.8℃)升(sheng)到200℃。

    圖5表明，在(zai)實(shi)(shi)驗(yan)的預冷段(duan)(O51A51或O52A52段(duan))，低(di)溫箱(xiang)(xiang)(xiang)溫度(du)在(zai)制冷系統啟動后迅速降低(di)，當(dang)溫度(du)接近(jin)預冷溫度(du)時，電加(jia)熱(re)(re)開始工(gong)作，箱(xiang)(xiang)(xiang)內溫度(du)逐漸穩定(ding)到設定(ding)值。實(shi)(shi)驗(yan)1經過(guo)3420s(約57min) ，低(di)溫箱(xiang)(xiang)(xiang)從室溫(13.8℃)降到- 70℃。在(zai)預冷、熱(re)(re)期間，測試箱(xiang)(xiang)(xiang)位于(yu)高溫箱(xiang)(xiang)(xiang)內，其(qi)內部熱(re)(re)環境變化與(yu)高溫箱(xiang)(xiang)(xiang)保(bao)持一致，當(dang)高溫箱(xiang)(xiang)(xiang)溫度(du)穩定(ding)在(zai)200℃ ±0. 3℃時，測試箱(xiang)(xiang)(xiang)溫度(du)為(wei)200℃±0. 5℃，表明測試箱(xiang)(xiang)(xiang)內溫度(du)均勻。為(wei)了減少沖(chong)擊實(shi)(shi)驗(yan)過(guo)程中低(di)溫箱(xiang)(xiang)(xiang)溫度(du)恢復時間，在(zai)低(di)溫箱(xiang)(xiang)(xiang)底(di)部、上(shang)部和側(ce)面增(zeng)加(jia)了鋁板來儲能。
    當(dang)高(gao)(gao)、低(di)(di)溫(wen)(wen)(wen)箱(xiang)分(fen)別(bie)達到(dao)預(yu)熱(re)、預(yu)冷溫(wen)(wen)(wen)度(du)(du)并維持到(dao)點A41(或A51)時(shi)刻，在氣缸的(de)作用下(xia)，測試(shi)箱(xiang)從高(gao)(gao)溫(wen)(wen)(wen)箱(xiang)沖擊(ji)(ji)(ji)到(dao)低(di)(di)溫(wen)(wen)(wen)箱(xiang)，轉(zhuan)換時(shi)間為(wei)(wei)(wei)5s，實驗1進(jin)入- 55℃沖擊(ji)(ji)(ji)階(jie)段(duan)。由圖(tu)4和圖(tu)5可以看出，由于測試(shi)箱(xiang)從高(gao)(gao)溫(wen)(wen)(wen)環(huan)境(jing)(200℃)沖擊(ji)(ji)(ji)到(dao)超(chao)低(di)(di)溫(wen)(wen)(wen)環(huan)境(jing)(-71℃)伴隨著熱(re)量的(de)轉(zhuan)移，低(di)(di)溫(wen)(wen)(wen)箱(xiang)溫(wen)(wen)(wen)度(du)(du)迅速上升， 經(jing)過(guo)272s(約4.5min)穩定到(dao)沖擊(ji)(ji)(ji)溫(wen)(wen)(wen)度(du)(du)-55℃ ，恢復時(shi)間約為(wei)(wei)(wei)4.5min(A51;A'51段(duan))。高(gao)(gao)溫(wen)(wen)(wen)箱(xiang)溫(wen)(wen)(wen)度(du)(du)下(xia)降(jiang)后(hou)上升，經(jing)過(guo)186s(3. 1min)穩定到(dao)210℃，恢復時(shi)間為(wei)(wei)(wei)3.1min(A41，A'41段(duan))。
    當穩定(ding)(ding)后(hou)(hou)的高、低溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(高溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang):210℃;低溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang): - 55℃)維持到(dao)點B，(或(huo)B，)時(shi)(shi)(shi)刻時(shi)(shi)(shi)，實(shi)驗1進人200℃沖(chong)擊階段(B-C)。在氣缸的作用下(xia)，測試(shi)箱(xiang)由低溫(wen)(wen)(wen)(wen)(wen)(wen)環境(-55℃)沖(chong)擊到(dao)高溫(wen)(wen)(wen)(wen)(wen)(wen)環境(210℃)，轉(zhuan)換時(shi)(shi)(shi)間(jian)為5s。由圖4和圖5可以看(kan)出，高溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)下(xia)降后(hou)(hou)_上升到(dao)200C并(bing)(bing)保持穩定(ding)(ding)，溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)恢復時(shi)(shi)(shi)間(jian)約(yue)2. 4min(B41，B'41段)。低溫(wen)(wen)(wen)(wen)(wen)(wen)箱(xiang)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)從-55℃下(xia)降并(bing)(bing)穩定(ding)(ding)到(dao)-70℃，溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)恢復時(shi)(shi)(shi)間(jian)約(yue)17min(B51，B'51段)。
    圖(tu)4和圖(tu)5中O42C42、O52C52分別為實(shi)(shi)驗(yan)2高、低溫(wen)箱溫(wen)度變化曲線，其(qi)趨勢與實(shi)(shi)驗(yan)1相同預(yu)(yu)冷、預(yu)(yu)熱(re)和沖(chong)擊過(guo)程中溫(wen)度恢復時間均(jun)少(shao)于(yu)實(shi)(shi)驗(yan)1。
    實驗(yan)結(jie)果表明，在整個沖(chong)擊(ji)循(xun)環試(shi)驗(yan)過(guo)程中，高溫箱經過(guo)約(yue)12.8min，預熱溫度(du)可(ke)達(da)到2109C，穩定偏差(cha)(cha)±0.3℃;低(di)溫箱經過(guo)約(yue)57min，預冷溫度(du)可(ke)達(da)到-71℃ ，穩定偏差(cha)(cha)±0.5℃。沖(chong)擊(ji)試(shi)驗(yan)在-55℃~+200℃時(shi)，轉換時(shi)間為5s，溫度(du)恢復時(shi)間不大于(yu)5min，溫度(du)偏差(cha)(cha)不大于(yu)±0.5℃ ，超高低(di)溫沖(chong)擊(ji)試(shi)驗(yan)箱性(xing)能(neng)達(da)到要(yao)求。

    6、結論

    選擇R404A/R23作為(wei)復疊式制冷循環的(de)制冷劑，搭(da)建了高低溫沖(chong)擊(ji)試驗(yan)(yan)箱(xiang)實驗(yan)(yan)裝置，并達(da)(da)到(dao)了在(zai)-55℃~+200℃的(de)沖(chong)擊(ji)溫度(du)范圍(wei)內的(de)技術要(yao)求。實驗(yan)(yan)結(jie)果表(biao)明，在(zai)制冷系統(tong)(tong)穩(wen)(wen)定工作后，壓縮機的(de)進、排氣口壓力穩(wen)(wen)定，且在(zai)許可(ke)(ke)范圍(wei)內，系統(tong)(tong)運行穩(wen)(wen)定可(ke)(ke)靠。實驗(yan)(yan)結(jie)果也表(biao)明，在(zai)高低溫調節(jie)過(guo)程中(zhong)，系統(tong)(tong)預(yu)熱溫度(du)達(da)(da)到(dao)210℃，預(yu)冷溫度(du)達(da)(da)到(dao)-70℃ ，預(yu)熱時(shi)(shi)間(jian)不大(da)于(yu)12. 8min，預(yu)冷時(shi)(shi)間(jian)不大(da)于(yu)57min。沖(chong)擊(ji)實驗(yan)(yan)過(guo)程中(zhong)，溫度(du)轉換時(shi)(shi)間(jian)為(wei)5s，溫度(du)恢復時(shi)(shi)間(jian)不大(da)于(yu)5min，溫度(du)偏差不大(da)于(yu)±0.5℃。