張洪宇,盧?軍,莊春龍,黃光勤,余?杰,劉亞姣
地下防護(hù)工程空調(diào)相變儲(chǔ)熱水池儲(chǔ)熱性能實(shí)驗(yàn)研究
張洪宇1,盧?軍2,莊春龍1,黃光勤1,余?杰1,劉亞姣1
(1. 陸軍勤務(wù)學(xué)院軍事設(shè)施系,重慶 401311;2. 重慶大學(xué)城市建設(shè)與環(huán)境工程學(xué)院,重慶 400044)
針對(duì)既有地下防護(hù)工程傳統(tǒng)空調(diào)冷卻水池儲(chǔ)熱能力不足,外置冷卻塔易造成工程紅外暴露而影響工程安全的問題,提出了采用空調(diào)相變冷卻水池方案以期增強(qiáng)系統(tǒng)儲(chǔ)熱能力,延長(zhǎng)工程隔絕防護(hù)條件下空調(diào)系統(tǒng)運(yùn)行保障時(shí)間.搭建了地下防護(hù)工程空調(diào)相變儲(chǔ)熱水池實(shí)驗(yàn)臺(tái),研究了定負(fù)荷條件下相變儲(chǔ)熱單元用量、冷卻水流量對(duì)相變儲(chǔ)熱水池儲(chǔ)熱性能的影響;考慮添加相變儲(chǔ)熱單元對(duì)水池儲(chǔ)熱能力與連續(xù)保障能力的影響,提出了地下防護(hù)工程空調(diào)相變儲(chǔ)熱水池儲(chǔ)熱性能評(píng)價(jià)指標(biāo):相變儲(chǔ)熱水池單位體積儲(chǔ)熱量和基于出口溫度定義的相變儲(chǔ)熱水池保障效能系數(shù).研究表明:向地下防護(hù)工程空調(diào)儲(chǔ)熱水池中加入相變單元能夠提升空調(diào)儲(chǔ)熱水池儲(chǔ)熱能力;與未加入相變儲(chǔ)熱單元的空調(diào)儲(chǔ)熱水池相比,當(dāng)相變儲(chǔ)熱單元體積占空調(diào)儲(chǔ)熱水池有效容積的2.84%、4.26%時(shí),相變儲(chǔ)熱水池單位體積儲(chǔ)熱量分別提高了6.35%和9.03%,相變儲(chǔ)熱水池保障效能系數(shù)分別提高了7%和11%,空調(diào)系統(tǒng)運(yùn)行保障時(shí)間分別延長(zhǎng)了1.77h和2.82h;在實(shí)驗(yàn)條件下,流速?gòu)?50L/h提高至450L/h時(shí),水池單位體積儲(chǔ)熱量和保障效能系數(shù)均有所降低,大流量工況(450L/h)下,相變儲(chǔ)熱單元存在未完全融化,水池儲(chǔ)熱能力與連續(xù)保障能力明顯降低,因此在不影響熱泵機(jī)組正常運(yùn)行和水池儲(chǔ)熱性能的情況下,適當(dāng)降低冷卻水流量對(duì)空調(diào)儲(chǔ)熱水池儲(chǔ)熱系統(tǒng)是有益的.
地下防護(hù)工程;空調(diào)冷卻水池;相變材料;相變儲(chǔ)熱
地下防護(hù)工程能正常運(yùn)轉(zhuǎn),要求工程內(nèi)部空氣的溫濕度必須保持在一定范圍內(nèi),而這正是通過通風(fēng)空調(diào)系統(tǒng)實(shí)現(xiàn)的.隨著電子設(shè)備的驟然增多,地下防護(hù)工程中余熱急劇增加[1],導(dǎo)致工程處于隔絕防護(hù)狀態(tài)時(shí),原有空調(diào)冷卻水池所能維持空調(diào)系統(tǒng)的運(yùn)行時(shí)間大大降低,而擴(kuò)建空調(diào)冷卻水池施工困難,加設(shè)冷卻塔易造成工程紅外暴露.
為解決傳統(tǒng)地下防護(hù)工程空調(diào)冷凝熱處理模式不足,學(xué)者們從增強(qiáng)工程隱蔽效果、冷凝熱處理模式轉(zhuǎn)換等方面做了大量工作.周滌生等[2]和馮爽[3]采用冷卻塔入地方案,應(yīng)用于上海外灘觀光隧道工程.王晉生等[4-5]和劉文杰等[6]提出防護(hù)工程非定型冷卻塔的設(shè)計(jì)理論,將冷卻塔置于地下空調(diào)冷卻水池上方,利用水池的水蒸發(fā)和柴油電站進(jìn)排風(fēng)帶走熱量,設(shè)計(jì)方案應(yīng)用在了上海某國(guó)防工程.何葉從等[7]研發(fā)了一種旋轉(zhuǎn)噴霧間接蒸發(fā)冷卻器,可安裝于地下建筑排風(fēng)通道內(nèi).耿世彬等[8]采用地下儲(chǔ)水箱和風(fēng)冷熱泵機(jī)組聯(lián)合的方式來(lái)替代冷卻塔.上述方案有的僅減少了紅外暴露點(diǎn),有的對(duì)使用地點(diǎn)及工程內(nèi)負(fù)荷分配要求較高.相變材料作為儲(chǔ)能的良好介質(zhì),如選擇合適的相變材料應(yīng)用于地下防護(hù)工程空調(diào)冷卻水池,在不增加水池容積的基礎(chǔ)上,可增加水體熱容量,延長(zhǎng)空調(diào)系統(tǒng)運(yùn)行時(shí)間.基于此,本文提出在空調(diào)冷卻水池中加入相變儲(chǔ)熱單元構(gòu)成空調(diào)相變冷卻水池,利用相變儲(chǔ)能技術(shù)解決既有空調(diào)冷卻水池儲(chǔ)熱量不足的問題.
為分析空調(diào)相變冷卻水池運(yùn)行特性,搭建了空調(diào)相變冷卻水池儲(chǔ)熱實(shí)驗(yàn)臺(tái).系統(tǒng)示意如圖1所示,實(shí)驗(yàn)臺(tái)實(shí)物圖如圖2所示.實(shí)驗(yàn)設(shè)備及主要儀器包括:管道加熱器、相變水池、相變儲(chǔ)熱單元、循環(huán)水泵、浮子流量計(jì)、管路部件以及T型熱電偶模塊、溫度采集儀等.
圖1?空調(diào)相變冷卻水池儲(chǔ)熱實(shí)驗(yàn)系統(tǒng)示意
(a)水池外觀 ?? (b)相變單元布置
管道加熱器額定功率2kW,水池規(guī)格(長(zhǎng)×寬×高)為1.3m×1.3m×1.2m,有效容積1.86m3,進(jìn)出口分別位于水池上下中心處.循環(huán)水泵為德國(guó)威樂管道泵,額定揚(yáng)程5m,額定流量13L/min.浮子流量計(jì)量程60~600L/h,精度為±2.5%.循環(huán)管道采用DN20鍍鋅鋼管,為減少實(shí)驗(yàn)過程熱損失,循環(huán)管道及水池四面用15mm厚橡塑保溫棉做保溫處理.熱電偶精度為±0.1℃,溫度采集頻率為1次/min.1#、8#熱電偶分別監(jiān)測(cè)水池入口、出口溫度,實(shí)驗(yàn)測(cè)點(diǎn)及相變儲(chǔ)熱單元布置見實(shí)驗(yàn)方案.
傳統(tǒng)的相變儲(chǔ)熱裝置一般只采用一種相變材料,已有研究表明,儲(chǔ)熱過程中儲(chǔ)熱裝置內(nèi)會(huì)出現(xiàn)溫度分層[9-11],嚴(yán)重時(shí)會(huì)出現(xiàn)靠近入口處相變材料已經(jīng)完全相變并迅速升溫,而遠(yuǎn)離入口處相變材料還未完成相變的不利情況.本文提出一種地下防護(hù)工程多熔點(diǎn)空調(diào)相變儲(chǔ)熱水池概念,即在地下防護(hù)工程空調(diào)冷卻水池中采用具有不同熔點(diǎn)的多種相變材料代替單一相變材料,根據(jù)熔點(diǎn)高低合理安排其排放位置,最大限度地利用相變潛熱儲(chǔ)熱,提高相變潛熱有效利用率.選用2種石蠟相變材料分別填充相變單元,其主要物性參數(shù)見表1.
表1?PCM-1和PCM-2相變石蠟的主要物性參數(shù)
Tab.1?Main physical parameters of the PCM-1 and PCM-2 phase change paraffin
考慮到相變材料對(duì)封裝材料的腐蝕性[12]以及封裝材料應(yīng)具有較高的導(dǎo)熱系數(shù),選用304不銹鋼進(jìn)行封裝,封裝尺寸為1.1m×0.1m×0.03m.
通過閥門開度的調(diào)節(jié)改變進(jìn)入儲(chǔ)熱水池的流量,研究冷卻水流量對(duì)空調(diào)儲(chǔ)熱水池流場(chǎng)及儲(chǔ)熱性能的影響,流量主要包括3種情況:250L/h、350L/h、450L/h.此外,通過調(diào)整相變單元的數(shù)量,研究相變儲(chǔ)熱單元用量對(duì)儲(chǔ)熱水池儲(chǔ)熱性能的影響,相變單元用量主要包括16個(gè)和24個(gè)兩種情況.實(shí)驗(yàn)過程中,為了研究?jī)?chǔ)熱水池內(nèi)部水體溫度分布情況,沿水池豎向高度布置2?!?#共6個(gè)熱電偶,熱電偶豎向間距19cm.同時(shí),為了觀測(cè)相變材料在儲(chǔ)熱過程中的溫度變化特性,在每層中間位置相變儲(chǔ)熱單元內(nèi)部布置1?!?#共4個(gè)相變溫度測(cè)點(diǎn),測(cè)點(diǎn)分別布置在4個(gè)相變單元的中心位置.相變單元及溫度測(cè)點(diǎn)具體布置方案見圖3.
(a)24個(gè)相變單元
(b)16個(gè)相變單元
圖3?相變儲(chǔ)熱單元及測(cè)點(diǎn)布置
Fig.3 Phase change heat storage unit and measuring point layout
國(guó)內(nèi)外學(xué)者對(duì)相變儲(chǔ)熱裝置的傳熱特性進(jìn)行了大量研究[13-15],并且有一些學(xué)者提出了相應(yīng)的評(píng)價(jià)指標(biāo)[16-17].但對(duì)于應(yīng)用于地下防護(hù)工程空調(diào)冷卻水池的評(píng)價(jià)指標(biāo)較少,本文依據(jù)相變儲(chǔ)熱水池的預(yù)期目標(biāo)效益,提出兩種指標(biāo)對(duì)空調(diào)相變水池的儲(chǔ)熱性能進(jìn)行定義和研究.
相變水池所能儲(chǔ)存的熱量是評(píng)價(jià)其儲(chǔ)熱能力的一個(gè)重要指標(biāo),對(duì)水池設(shè)計(jì)容量的確定具有重要指導(dǎo)意義.當(dāng)冷卻水流速不變時(shí),其計(jì)算方法為
為了更加科學(xué)指導(dǎo)相變水池的設(shè)計(jì),定義相變儲(chǔ)熱水池單位體積儲(chǔ)熱量作為相變儲(chǔ)熱水池儲(chǔ)熱能力評(píng)價(jià)指標(biāo)之一,其計(jì)算式為
作為添加相變儲(chǔ)熱單元儲(chǔ)熱效果的對(duì)比依據(jù),本文實(shí)驗(yàn)研究了未加入相變儲(chǔ)熱單元的空調(diào)冷卻水池儲(chǔ)熱性能.圖4為未加入相變儲(chǔ)熱單元空調(diào)儲(chǔ)熱水池出入口溫度變化情況.
圖4 未加入相變儲(chǔ)熱單元空調(diào)儲(chǔ)熱水池進(jìn)出口溫度變化
為了研究不同相變儲(chǔ)熱單元用量對(duì)空調(diào)相變儲(chǔ)熱水池儲(chǔ)熱性能的影響,開展了2種不同相變單元數(shù)量的儲(chǔ)熱實(shí)驗(yàn):16個(gè)相變單元、24個(gè)相變單元.其中16個(gè)相變單元的相變材料填充量為PCM-1、PCM-2各22kg;24個(gè)相變單元的相變材料填充量為PCM-1、PCM-2各33kg.
圖5 不同數(shù)量相變儲(chǔ)熱單元下空調(diào)儲(chǔ)熱水池進(jìn)出口溫度變化
表2為不同相變儲(chǔ)熱單元數(shù)量下儲(chǔ)熱水池性能分析情況.
表2?不同相變儲(chǔ)熱單元數(shù)量下空調(diào)儲(chǔ)熱水池性能
Tab.2 Performance of air-conditioning reservoir under different quantities of phase change heat storage units
在水池加熱功率基本不變的情況下,水池進(jìn)口流量與進(jìn)口溫度為一對(duì)耦合變量,提高流量則進(jìn)口溫度降低,降低流量則進(jìn)口溫度提高,與大部分現(xiàn)有地下防護(hù)工程空調(diào)系統(tǒng)運(yùn)行時(shí)負(fù)荷基本為定值的情況較一致.
圖6為空調(diào)相變儲(chǔ)熱水池在不同進(jìn)口流量下的進(jìn)出口溫度變化情況,圖7為空調(diào)相變儲(chǔ)熱水池在不同進(jìn)口流量下的進(jìn)出口平均溫度變化情況.
圖6?不同進(jìn)口流量下的進(jìn)出口溫度
圖7?不同進(jìn)口流量下的進(jìn)出口平均溫度
由圖6還可以看出,冷卻水流量為250L/h時(shí),在儲(chǔ)熱開始的前2.76h,進(jìn)出口溫度幾乎沒有變化,主要原因在于由于冷卻水的流量較小,溫度從上向下擴(kuò)散需要較長(zhǎng)時(shí)間,這段時(shí)間進(jìn)入空調(diào)儲(chǔ)熱水池的冷凝熱主要由上部水體儲(chǔ)存.通過分析2#~7#熱電偶監(jiān)測(cè)溫度可知相變儲(chǔ)熱水池豎向溫度分布情況,流量為250L/h時(shí)水溫的分層現(xiàn)象比較明顯(見圖9(a)).主要原因在于流量較小,冷卻水進(jìn)出口溫差較大.豎向溫度梯度較大.當(dāng)冷卻水流量增大到350L/h、450L/h時(shí),冷卻水進(jìn)出口溫差減少,空調(diào)儲(chǔ)熱水池中對(duì)流作用增強(qiáng),熱擴(kuò)散迅速,豎向溫度分布較均勻,分層現(xiàn)象較小流量時(shí)明顯減弱(見圖9(b)、(c)).
圖8?流量為450L/h時(shí)相變儲(chǔ)熱單元內(nèi)部溫度變化
表3為變流量實(shí)驗(yàn)工況下相變儲(chǔ)熱水池儲(chǔ)熱性能分析統(tǒng)計(jì).
可見,在既有空調(diào)儲(chǔ)熱水池中加入相變儲(chǔ)熱單元,在儲(chǔ)熱過程中當(dāng)相變儲(chǔ)熱單元完全相變情況下,改變進(jìn)口流量對(duì)相變儲(chǔ)熱水池儲(chǔ)熱性能影響微弱.在實(shí)際應(yīng)用中,如增加冷卻水流量即提高流速,則泵需要消耗更多的功,儲(chǔ)熱過程能量損耗提高,因此在不影響熱泵機(jī)組正常運(yùn)行和水池儲(chǔ)熱性能的情況下,適當(dāng)降低流量對(duì)儲(chǔ)熱系統(tǒng)是有益的.
表3?變流量實(shí)驗(yàn)工況下相變儲(chǔ)熱水池儲(chǔ)熱性能
Tab.3?Thermal storage performance of the phase change heat storage resevoir under variable flow experimental conditions
(a)250 L/h
(b)350 L/h
(c)450 L/h
本文對(duì)地下防護(hù)工程空調(diào)相變儲(chǔ)熱水池儲(chǔ)熱性能進(jìn)行了實(shí)驗(yàn)研究,提出了相變儲(chǔ)熱水池單位體積儲(chǔ)熱量和基于出口溫度定義的相變儲(chǔ)熱水池保障效能系數(shù),分析了相變單元用量和冷卻水流速對(duì)相變水池儲(chǔ)熱能力的影響,主要得到如下結(jié)論.
(2) 在實(shí)驗(yàn)條件下,流速?gòu)?50L/h提高至450L/h時(shí),水池單位體積儲(chǔ)熱量和保障效能系數(shù)均有所降低,大流量工況(450L/h)下,相變儲(chǔ)熱單元存在未完全融化情況,水池儲(chǔ)熱能力與連續(xù)保障能力明顯降低.
[1] 訾冬毅,繆小平,劉文杰. 蒸發(fā)式冷凝器在地下工程中的應(yīng)用[J]. 制冷與空調(diào),2009,9(3):36-40.
Zi Dongyi,Liao Xiaoping,Liu Wenjie. Application of evaporative condenser into underground project[J]. Refrigeration and Air-Conditioning,2009,9(3):36-40(in Chinese).
[2] 周滌生,李祥麟. 地下冷卻塔在外灘觀光隧道中的應(yīng)用[J]. 上海建設(shè)科技,2002,93(3):20-21.
Zhou Disheng,Li Xianglin. Application of underground cooling tower in the Bund sightseeing tunnel[J]. Shanghai Construction Technology,2002,93(3):20-21(in Chinese).
[3] 馮?爽. 地下式冷卻塔設(shè)計(jì)實(shí)例及其發(fā)展前景[J]. 地下工程與隧道,2004,18(14):46-52.
Feng Shuang. Design and development of underground cooling tower[J]. Underground Engineering and Tunnel,2004,18(14):46-52(in Chinese).
[4] 王晉生. 防護(hù)工程冷凝熱處理過程作用機(jī)理及設(shè)計(jì)理論研究[D]. 南京:解放軍理工大學(xué),2009.
Wang Jinsheng. Study on Mechanism and Design Theory of Condensation Heat Treatment Process in Protective Engineering[D]. Nanjing:PLA University of Science and Technology,2009(in Chinese).
[5] 王晉生,劉文杰,蔡?浩,等. 地下蓄冷防護(hù)型冷卻塔[J]. 制冷與空調(diào)(四川),2010,24(5):1-5.
Wang Jinsheng,Liu Wenjie,Cai Hao,et al. Underground thermal storage defensive cooling tower[J]. Refrigeration & Air Conditioning,2010,24(5):1-5(in Chinese).
[6] 劉文杰. 防護(hù)工程冷凝熱處理模式及相關(guān)設(shè)備研究[D]. 南京:解放軍理工大學(xué),2009.
Liu Wenjie. Research on Condensation Heat Treatment Mode and Related Equipment of Protective Engineering[D]. Nanjing:PLA University of Science and Technology,2009(in Chinese).
[7] 何葉從,鄒國(guó)榮,肖益民,等. 間接蒸發(fā)冷卻用氣-水霧化噴嘴特性器實(shí)驗(yàn)研究[J]. 重慶建筑大學(xué)學(xué)報(bào),2008,30(6):105-109.
He Yecong,Zou Guorong,Xiao Yimin,et al. Spray characteristics of a two phase air-water nozzle for indirect evaporative cooling[J]. Journal of Chongqing Jianzhu University,2008,30(6):105-109(in Chinese).
[8] 耿世彬,李?永,韓?旭. 水環(huán)熱泵空調(diào)系統(tǒng)在地下工程中的應(yīng)用[J]. 解放軍理工大學(xué)學(xué)報(bào):自然科學(xué)版,2011,12(2):139-144.
Geng Shibin,Li Yong,Han Xu. Water loop heat pump system in underground engineering[J]. Journal of PLA University of Science and Technology:Natural Science Edition,2011,12(2):139-144(in Chinese).
[9] 于國(guó)清,湯金華,呂?靜. 水-相變材料復(fù)合蓄熱裝置的溫度分布模型研究[J]. 流體機(jī)械,2009,37(11):65-68.
Yu Guoqing,Tang Jinhua,Lü Jing. Research on temperature stratification model of water-PCM hybrid thermal storage[J]. Fluid Machinery,2009,37(11):65-68(in Chinese).
[10] 于國(guó)清,湯金華,趙慧忠. 水-相變材料復(fù)合蓄熱裝置的充放熱特性研究[J]. 流體機(jī)械,2010,38(7):59-62.
Yu Guoqing,Tang Jinhua,Zhao Huizhong. Research on the thermal charge and discharge of water-PCM hybrid thermal storage[J]. Fluid Machinery,2010,38(7):59-62(in Chinese).
[11] 湯金華. 太陽(yáng)能供熱系統(tǒng)中水-相變材料復(fù)合蓄熱研究[D]. 上海:上海理工大學(xué),2008.
Tang Jinhua. Study on Composite Heat Storage of Water-Phase Change Materials in Solar Heating System[D]. Shanghai:Shanghai University of Technology,2008(in Chinese).
[12] 鐵生年,柳?馨. 相變材料的腐蝕性與封裝材料研究進(jìn)展[J]. 材料導(dǎo)報(bào),2016,29(6):138-143.
Tie Shengnian,Liu Xin. Research progress of corrosivity of phase change material and relevant packaging materials[J]. Material Guide,2016,29(6):138-143(in Chinese).
[13] Niyas H,Prasad S,Muthukumar P. Performance investigation of a lab-scale latent heat storage prototype-Numerical results[J]. Energy Conversion & Manage-ment,2017,135(3):188-199.
[14] Regin A F,Solanki S C,Saini J S. Heat transfer characteristics of thermal energy storage system using PCM capsules:A review[J]. Renewable & Sustainable Energy Reviews,2008,12(9):2438-2458.
[15] Zheng H,Wang C,Liu Q,et al. Thermal performance of copperfoam/paraffin composite phase change material[J]. Energy Conversion and Management,2018,157(2):372-381.
[16] Niyas H,Rao C R C,Muthukumar P. Performance investigation of a lab-scalelatent heat storage prototype-experimental results[J]. Solar Energy,2017,155 (10):971-984.
[17] Yang J,Yang L,Xu C,et al. Experimental study on enhancement of thermal energy storage with phase-change material[J]. Applied Energy,2016,169(5):164-176.
Performance of the Phase Change Heat Storage Air-Conditioning Reservoir for Underground Protective Engineering
Zhang Hongyu1,Lu Jun2,Zhuang Chunlong1,Huang Guangqin1,Yu Jie1,Liu Yajiao1
(1. Department of Military Facilities,Army Logistic University of PLA,Chongqing 401311,China;2. School of Urban Construction and Environmental Engineering,Chongqing University,Chongqing 400044,China)
Aiming for the insufficient thermal storage capability of the traditional air-conditioning reservoir and the problem of engineering safety caused by infrared exposure on the external cooling tower for existing underground protective engineering,the phase change storage reservoir scheme is proposed to strengthen the thermal storage capability and to prolong the run time of the HVAC system under the isolation protection condition. An experiment on the phase change heat storage air-conditioning reservoir was conducted,and the effects of the quantity of the phase change heat storage unit and the water mass flow on the capability of the reservoir are analyzed under the fixed load condition. To analyze the effects of the phase change heat storage unit on the heat storage capacity and continuous safeguarding capacity of the reservoir,the following performance parameters of the phase change heat storage reservoir for underground protective engineering are proposed:Heat storage capacity per unit volume and safeguarding efficiency of the phase change heat storage pool. The results show that adding the phase change heat storage unit can significantly improve the heat storage capacity of the reservoir. Compared with the reservoir without phase change heat storage unit,when the volume of the phase change heat storage unit accounts for 2.84% and 4.26% of the effective volume of the reservoir,the heat storage capacity per unit volume of the phase change heat storage reservoir is increased by 6.35% and 9.03%,the guaranteed efficiency coefficient of the phase change heat storage reservoir is increased by 7% and 11%,and the guaranteed operation time is prolonged by 1.77h and 2.82 h,respectively. Under the experimental conditions,when the flow rate is increased from 250 L/h to 450 L/h,the heat storage capacity per unit volume and guaranteed efficiency coefficient are both reduced. When the flow rate is high (450 L/h),the phase change heat storage units do not melt completely and the heat storage capacity and guaranteed continuous capacity of the pool are significantly reduced. Therefore,properly reducing the cooling water flow rate is beneficial to the heat storage system of the reservoir without affecting the operation of the heat pump unit and the heat storage performance of the reservoir.
underground protective engineering;air-conditioning reservoir;phase change material;phase change heat storage
TK02
A
0493-2137(2019)11-1187-07
10.11784/tdxbz201812004
2018-12-03;
2018-12-28.
張洪宇(1981—??),男,博士研究生,講師,13883291029@163.com.
盧?軍,lujun66@vip.sina.com.
國(guó)家重點(diǎn)研發(fā)計(jì)劃資助項(xiàng)目(2017YFC0806305);國(guó)家自然科學(xué)基金資助項(xiàng)目(51706243).
Supported by the National Key Research and Development Program of China(No.2017YFC0806305),the National Natural Science Foundation of China(No.51706243).
(責(zé)任編輯:田?軍)