新能源汽車(che)如(ru)果不能在(zai)(zai)車(che)輛行(xing)駛(shi)過程中及(ji)時帶(dai)走熱量,勢(shi)必會(hui)影(ying)響電(dian)(dian)(dian)(dian)池(chi)的(de)工作性能和使(shi)(shi)用壽命,甚至可(ke)能給行(xing)車(che)安全帶(dai)來大的(de)隱(yin)患。對鋰(li)離子(zi)電(dian)(dian)(dian)(dian)池(chi)而言,高溫(wen)加速動力電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)、隔板等部件的(de)老化。同時溫(wen)度(du)不均衡將增(zeng)大電(dian)(dian)(dian)(dian)池(chi)組(zu)間的(de)物(wu)性差異性,從而破壞電(dian)(dian)(dian)(dian)池(chi)之間的(de)一致性,造成單體(ti)電(dian)(dian)(dian)(dian)池(chi)間的(de)性能不匹(pi)配,較終使(shi)(shi)整(zheng)組(zu)電(dian)(dian)(dian)(dian)池(chi)提(ti)前(qian)失效(xiao)。溫(wen)度(du)過低充電(dian)(dian)(dian)(dian)時會(hui)引發鋰(li)離子(zi)還(huan)原成金屬鋰(li)枝晶體(ti),易刺穿電(dian)(dian)(dian)(dian)池(chi)內部隔膜(mo),引發電(dian)(dian)(dian)(dian)車(che)內部短路,存在(zai)(zai)安全隱(yin)患。因此,有效(xiao)的(de)電(dian)(dian)(dian)(dian)池(chi)組(zu)熱管理(BTM)是(shi)混合動力(li)汽車(HEV)在不(bu)同環境條件(jian)及(ji)工況下*的工作(zuo),也是動力電(dian)池良好(hao)循(xun)環壽命和安全工作(zuo)的保障。
電池(chi)(chi)包水(shui)冷系(xi)統熱(re)(re)(re)(re)(re)(re)管(guan)理方式(shi)動(dong)力(li)電池(chi)(chi)熱(re)(re)(re)(re)(re)(re)管(guan)理從(cong)性(xing)質(zhi)(zhi)上可以(yi)分為(wei)降溫(wen)(wen)(wen)過程(cheng)熱(re)(re)(re)(re)(re)(re)管(guan)理和升溫(wen)(wen)(wen)過程(cheng)熱(re)(re)(re)(re)(re)(re)管(guan)理。升溫(wen)(wen)(wen)熱(re)(re)(re)(re)(re)(re)管(guan)理就是(shi)當電池(chi)(chi)所處的環境溫(wen)(wen)(wen)度過低時,升高電池(chi)(chi)箱的溫(wen)(wen)(wen)度,讓(rang)電池(chi)(chi)內的活(huo)性(xing)物質(zhi)(zhi)發揮其效(xiao)應(ying),提高電池(chi)(chi)利用率。電池(chi)(chi)加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)的方法主(zhu)要(yao)有外部(bu)熱(re)(re)(re)(re)(re)(re)氣體加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)、加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)絲(si)加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)、加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)板加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)、加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)膜加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)等。由于氣體導熱(re)(re)(re)(re)(re)(re)系(xi)數較低,加(jia)(jia)(jia)熱(re)(re)(re)(re)(re)(re)效(xiao)果不明顯:加(jia)熱絲和加(jia)熱膜等(deng)加(jia)熱方法普遍存在(zai)電池(chi)組(zu)內部溫(wen)度不(bu)均衡(heng)現象。
目前(qian)應用較多的(de)熱(re)管理方式(shi)主要有強制(zhi)風(feng)(feng)冷(leng)法(fa)(fa)、液(ye)體冷(leng)卻(que)(que)法(fa)(fa)、相變(bian)材料(liao)冷(leng)卻(que)(que)法(fa)(fa)等。強制(zhi)風(feng)(feng)冷(leng)法(fa)(fa)是以空(kong)氣為冷(leng)卻(que)(que)介質,在風(feng)(feng)機的(de)驅(qu)動下(xia)(xia)對(dui)電(dian)(dian)池(chi)(chi)(chi)包進行(xing)冷(leng)卻(que)(que)的(de)方法(fa)(fa)。電(dian)(dian)池(chi)(chi)(chi)模塊內(nei)的(de)溫度差異與電(dian)(dian)池(chi)(chi)(chi)組(zu)的(de)布置、通(tong)風(feng)(feng)方式(shi)有著很大的(de)關系。一般情況下(xia)(xia),電(dian)(dian)池(chi)(chi)(chi)包內(nei)邊緣電(dian)(dian)池(chi)(chi)(chi)散熱(re)條件相對(dui)較好,中間位(wei)置的(de)電(dian)(dian)池(chi)(chi)(chi)容易積(ji)累(lei)熱(re)量,電(dian)(dian)池(chi)(chi)(chi)組(zu)的(de)熱(re)均衡性(xing)相對(dui)較差。
電池(chi)包水冷(leng)系(xi)統液(ye)(ye)(ye)體(ti)冷(leng)卻(que)(que)法是以(yi)液(ye)(ye)(ye)體(ti)作為(wei)(wei)傳熱介質,配以(yi)冷(leng)卻(que)(que)液(ye)(ye)(ye)泵和(he)熱交(jiao)換器的冷(leng)卻(que)(que)方式。液(ye)(ye)(ye)體(ti)冷(leng)卻(que)(que)分為(wei)(wei)直接接觸冷(leng)卻(que)(que)和(he)非直接接觸冷(leng)卻(que)(que)兩(liang)種(zhong)。非直接接觸傳熱(如(ru)傳熱管(guan)、夾套等(deng)),傳熱(re)介(jie)質(zhi)可(ke)(ke)以用水、乙二醇等。對(dui)于(yu)(yu)直接接觸(chu)傳熱(re),可(ke)(ke)采用礦(kuang)物油作為(wei)傳熱(re)介(jie)質(zhi)。在模(mo)塊和(he)傳熱(re)介(jie)質(zhi)之間(jian)進行(xing)傳熱(re)的速(su)率取(qu)決于(yu)(yu)液體的熱(re)導(dao)率、粘(zhan)度(du)、密度(du)和(he)流(liu)動速(su)率等,因此在選擇(ze)傳熱(re)介(jie)質(zhi)時,盡(jin)量選擇(ze)熱(re)導(dao)率高(gao),流(liu)動性好的流(liu)體。
相(xiang)變(bian)(bian)冷卻法(fa)是(shi)采用相(xiang)變(bian)(bian)材料進行(xing)熱(re)傳(chuan)遞,利用相(xiang)變(bian)(bian)材料的狀態變(bian)(bian)化(hua)吸(xi)收電(dian)池(chi)(chi)散(san)發出來的熱(re)量(liang),這(zhe)種(zhong)方法(fa)需(xu)要在電(dian)池(chi)(chi)之間(jian)填充(chong)相(xiang)變(bian)(bian)材料,這(zhe)將增(zeng)加整體的質量(liang),填充(chong)的越(yue)緊密,交換的熱(re)量(liang)越(yue)多(duo),這(zhe)就造成電(dian)池(chi)(chi)箱在組(zu)裝時(shi)的困(kun)難,在電(dian)池(chi)(chi)箱進行(xing)調試與維(wei)修(xiu)時(shi)也為相(xiang)變(bian)(bian)的覆蓋而造成不必要的麻(ma)煩。