一种新型相变蓄热材料的实验研究
江汉石油学院学报 2001年12月 第23卷 第4期
Journal of J i anghan Petroleu m I n stitute D ec 12001 Vo l 123 N o 14一种新型相变蓄热材料的实验研究
林怡辉,张正国,王世平 (华南理工大学教育部传热与节能开放研究实验室,广东广州510640)
[摘要]将有机相变蓄热材料与导热系数高的无机物进行纳米复合的创新方法,克服现有有机蓄能材料存在
液体渗漏、传热率低、相变时体积变化、有可燃性、对母体材料有副作用以及无机蓄能材料存在腐蚀性、相变
过程中具有过冷和反相等缺点,将有机相变材料嵌入到导热系数较高的二氧化硅纳米层空间内,制备有机
无机纳米复合相变蓄热材料。采用扫描电镜、红外光谱分析仪、差示扫描量热分析仪、导热系数仪分析制备
的复合相变材料,结果表明,复合相变材料是多孔纳米复合材料,其蓄热能力较好、导热性能好。
[关键词]复合材料;相变;潜热;蓄热;热导率;纳米材料
[中图分类号]TB 33;TB 34;TB 383[文献标识码]A [文章编号]10009752(2001)04008103
相变蓄热材料可用于解决热能供给和需求失配的矛盾,是提高能源利用效率和保护环境的重要材料。因相变蓄热材料具有蓄热密度大、蓄放热过程近似等温、过程易控制等优点,所以利用其固液、固固相变潜热来蓄热的技术倍受关注。常用的相变蓄热材料主要包括有机物和无机物两大类。绝大多数无机物相变蓄热材料具有腐蚀性而且在相变过程中具有过冷和相分离的缺点,影响了其蓄热能力;而有机物相变蓄热材料不仅腐蚀性小、在相变过程中几乎没有过冷和相分离的缺点,且化学性能稳定、价格便宜。在太阳能利用和建筑物采暖及空调的节能等领域,有机物相变蓄热材料的应用十分普遍[1～3],但有机物相变蓄热材料普遍存在导热系数低的缺点,致使其在蓄热系统的应用中传热性能差、蓄热量利用率低,从而降低了系统的效能。为了提高蓄热系统的效能,国内外许多研究者采用不同方法来强化有机相变蓄热材料在蓄放热过程中的传热,但均是从外部着手,未能解决有机相变材料导热系数低的本质问题。因此,研制蓄热密度大、导热系数高、性能稳定的新型复合相变蓄热材料成为国际上该研究领域的热点和难点。笔者通过实验研究的一种新型相变蓄热材料正是在这一研究领域的一次尝试。
1 新型相变蓄热材料的制备
通过实验制备的新型相变蓄热材料是一种兼具母体无机材料导热性能好和有机相变材料蓄热能力强的有机无机复合相变蓄热材料。
实验采用正硅酸乙酯(T EO S )为前驱体、
硬脂酸为相变材料、乙醇(ETOH ))为溶剂、盐酸为催化剂进行溶胶凝胶反应,制备复合相变蓄热材料。制备过程分为两步:第一步为溶胶的制备,第二步为溶胶凝胶的转化。凝胶是指含有微孔和聚合链的相互连接的网络[4]。
实验步骤为:按一定比例取T EO S 、ETOH 、H 2O 若干毫升置于烧杯中;用定时恒温磁力搅拌器加热搅拌溶液,将温度控制在60℃加热150m in,搅拌速度控制在中档;溶液加热搅拌15m in 后,加入少许HC l 催化剂;加热搅拌30m in 后把硬脂酸加入溶液中;加热过程中,溶液开始较浑浊,当加入HC l 催化剂后溶液一直保持透明;加热完毕,把样品放人烘箱烘干,直至产品恒重。
2 新型相变蓄热材料的表征211 扫描电镜表征
实验在60℃、pH 值为3、T EO S ∶ETOH ∶H 2O 摩尔比为1∶315∶7、硬脂酸适量、搅拌速度中挡、陈?
18? ()[基金项目]科技部“973”项目;广东省自然科学基金资助项目。
[收稿日期]20010514
化温度为80℃条件下,制备的复合材料外观为白色颗粒状固体物质。将复合材料样品置于扫描电镜下观察,显示粒径范围40～90nm ,说明该复合材料是颗粒状纳米材料。
212 红外光谱分析
图1 样品的红外光谱图
分别将制备的复合材料、二氧化硅及实验用
硬脂酸作红外衍射测试,其谱图如图1所示。从
图1可知,自上而下,第一条曲线与纯二氧化硅
的红外衍射图相吻合,二氧化硅的最强吸收峰为
1 082c m -1,这是Si —O 键的振动所致,位于
800c m -1,467c m -1的吸收峰也是Si —O 键的
振动所致;3 461c m -1的吸收峰表示有水存在;
位于957c m -1的吸收峰表明≡Si —OH 的存在;
1 642c m -1的较弱吸收峰,对应于残存的有机
物。第二条曲线在2 919c m -1,2 850c m -1处具
有很强的吸收峰,它们是由CH 3—,CH 2—键振
动所引起的吸收谱带;在1 703c m -1的吸收峰表
明羧基的存在。第三条曲线在2 919c m -1,
2 850c m -1,1 704c m -1,1 082c m -1处具有吸收
峰,说明复合材料并未有新的基团生成。由以上
分析可知,硬脂酸与二氧化硅仅仅是嵌合的关
系,而没有生成新的物质。
213 差示扫描量热分析
为了寻求复合材料的最佳组分配比,实验过
程中不断改变硬脂酸的加入量,并将制得的样品分别进行差示扫描量热分析测试。本实验制备新型复合相变材料的目的是为了得到既具有较高蓄热能力又有一定导热能力的材料。理论上复合材料中硬脂酸的含量越大,其蓄热能力越强;但二氧化硅母体材料的复合能力是有限的。因此,通过大量实验来确定硬脂酸在母体材料中的添加量是十分必要的。实验中硬脂酸的添加量(质量百分含量)分别为918%,2111%,2611%,4315%,47%,测得其潜热蓄热量分别为262,334,338,375,323J g,可见,相同质量的硬脂酸在复合材料样品中的蓄热能力比纯硬脂酸强。实验发现,复合相变材料的蓄热能力可高达16312J g,其相变温度约为55118℃,比纯硬脂酸的相变温度(62171℃)低,其潜热蓄热量约为纯硬脂酸的8219%。此外,随着硬脂酸含量的变化,复合材料相变温度也发生相应变化,这是因为表面张力引起蓄热物微粒的性质与其在堆积状态时不同。
214 导热系数测定
复合相变材料导热系数的大小,直接影响对材料蓄热能力的利用效率。用Q TM 2500型导热仪测得实
验制备的复合相变材料(硬脂酸质量百分含量2611%)的导热系数(25℃,固态)为01348W
(m K ),而在相同条件下分析纯硬脂酸的导热系数为01162W
(m K )。3 实验结果与讨论
311 相变材料比例的影响
由于相变材料的量直接影响复合材料的蓄热能力,也对复合材料的导热能力有一定影响,所以通过实验研究复合材料中相变材料的最佳比例是十分必要的。实验过程中,在相同的母体材料中加入不同量的硬脂酸,将得到的复合材料作D SC 测试。结果表明,随着硬脂酸在复合材料中的质量含量的增加,复合材料样品的潜热蓄热量也相应增加,而且其潜热蓄热量均比硬脂酸与二氧化硅简单混合的量大。
此外,样品中硬脂酸的质量含量的增加与其比热容的增加值不呈线性关系(图2)。当硬脂酸含量大于?28? 江 汉 石 油 学 院 学 报2001年12月
图2 样品中硬脂酸含量与比热容的关系
硬脂酸含量为4315%的复合材料蓄热量有所
下降。从保守的角度考虑,选择质量百分含量
为2611%的样品的组分配比比较好。若硬脂
酸仅是简单与二氧化硅混合,其潜热蓄热量
的计算值比实测值低很多,这难以用常规方
法解释。从样品的扫描电镜图可见硬脂酸与
二氧化硅是在分子水平上复合而形成纳米颗
粒,所以导致其性质上的变化。经过大量实验
验证,质量百分含量为2611%的样品的组分
配比是所有样品中较理想的,而且其可重复
性好。
312 相变材料蓄热效率比较实验制备的复合相变材料比纯硬脂酸的导热系数高,但潜热蓄热量没有纯硬脂酸大。为了比较两者的蓄热效率,设计了蓄放热实验来进行对比。
实验将相同体积的蓄热材料与纯硬脂酸相变材料分别置于密闭绝热容器中,进行蓄热实验对比。金属螺旋盘管埋于相变材料中,以水为传热流体,分别在金属螺旋盘管入水处、复合相变材料上层和下层接热电偶,并与数据采集器相连。实验结果表明,复合相变材料达到相变温度需要60m in,而相同条件下纯硬脂酸达到相变温度则需100m in 。可见,单位体积复合相变材料的蓄热效率比纯硬脂酸高。
4 结 语利用溶胶凝胶法制备硬脂酸 二氧化硅复合相变蓄热材料,其中硬脂酸的蓄热能力比纯硬脂酸强,蓄热量大,这说明硬脂酸与二氧化硅复合后提高了其单位蓄热能力。而且,复合材料的导热系数比纯有机酸的导热系数大,提高了相变蓄热材料的蓄放热速率,从而提高了相变蓄热材料对热能的利用效率。此外,复合相变蓄热材料的稳定性好,在反复蓄放热过程中没有液体出现。
以太阳能、废热、余热为主要热源,利用复合相变蓄热材料作建筑材料、恒温保温设备的衬材、各类保温和取暖设备、医疗设备等,都具有良好的前景。
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?38?第23卷第4期林怡辉等:一种新型相变蓄热材料的实验研究
69A New Techn ique for Treati ng I n jection W ater i n W ennan O ilf ield
CHEN Gua n 2lia ng ,L I Xue 2s ong ,WAN L iu 2fa (Z hongy uan O ilf ield B ranch Co mp any ,S IN O P EC ,P uy ang 457073)
Abstract :In considerati on of seri ous co rro sive and scaling p roblem s caused by m ixing injecti on of fresh w ater w ith sew age w ater ,w h ich are treated respectively befo rehand in W ennan O ilfield ,a technical research is carried out on the injecti on of the fresh w ater m ixed w ith sew age w ater befo rehand 1T he studies include the basic geo logic situati on ,technique fo r i m p roving the w ater quality ,its si m ulati on and field testing 1T he characteristics of the m ain p rocess fo r the new technique consist of sew age w ater deo iling befo rehand ,moving the po int of bactericide fo r w ard of m ixing disinflecting ,op ti m izing the design of the internal structure of a p ri m ary p reci p itati on tank and overall reconstructi on of a p ressure filtering tank 1F ield app licati on p roves that the technique could effectively contro l the co rro sive rate and scaling rate in the system 1
Key words :injecti on w ater ;sew age w ater ;w ater treatm ent ;W ennan O ilfield
71Rules and Coun ter m easures of Casi ng Fa ilure i n I n jecti ng and Produc i ng W ells i n Reg ion 4of Gudong O ilf ield L I U D ia n 2ta o ,L I L in 2x ia ng ,DU S hu 2li ,ZHAO C ha ng 2ge ,Y AO You 2long ,CHEN M ing 2lia ng (S heng li P etroleum A dm in istra tion B u reau ,D ongy ing 257237)
Abstract :T h rough a classificati on analysis on casing defo r m ati on w ells in R egi on 4of Gudong O ilfield ,rules of casing failures occurred vertically ,ho rizontally and w ith the ti m e being are studied ,the fo r m ing m echanis m s of casing failures in w ells are discussed emphatically 1It is found that sand p roducti on and h igh p ressure w ater injecti on are the m ain reasons fo r increasing the casing failure w ells 1Strengthening sand contro l ,moderate w ater injecti on and p roper contro l of p roducing p ressure differential are put fo r w ard as i m po rtant m easures fo r p reventing casing from failing 1Key words :casing ;casing w ell ;casing failure ;m echanis m ;p reventi on ;Gudong O ilfield
74P ipe Str i ng Stuck -po i n t Calculati ng Equation s and The ir Application
L I U C ong 2jie ,ZHOU X ia ng 2y i ,ZHANG Ya n (S heng li O ilf ield ,D ongy ing 257237)
FANG Yong (S u ix i W a ter A dm in istra tion and S up erv ision S ection of A nhu i P rov ince ,S u ix i 235100)
Abstract :Fo rce 2summ ing analyses are m ade respectively on a single p i pe string and a com bined string stuck in w ells 1Calculating equati ons are derived fo r the single p i pe string and com bined string by using the theo ry of differential and integral calculus based on a lifting m ethod and Hook’s law 1T he case study show s that the dep th of calculated stuck 2po int obtained w ith the equati ons has less erro rs w ith that of the real stuck 2po int 1
Key words :p i pe string ;stuck 2po int ;fo rce 2summ ing analysis ;stuck 2po int detecti on ;calculati on ;equati on
77Energy -sav i ng Eff ic iency of a D ef lecti ng W heel Beam Pu m p i ng Un it
DA I J ing 2jun (J iang han P etroleum Institu te ,J ing z hou 434102)
D I N G X ia n 2fe ng ,T ANG Hong (N o 12P etroleum M ach inery M anuf actu ring F actory H uabei ,R enqiu 062552)
Abstract :In considerati on of energy 2saving indicati ons of the po lished rod dynamom eter card (load on suspensi on po int ),net to rque of crank shaft ;roo t 2m ean 2square pow er ,cyclic loading rate and overall surface efficiency ,comparative analyses are m ade on the energy 2saving results of conventi onal beam pump ing units ,out phase pump ing units and deflecting w heel beam pump ing units ,the results show that obvi ous energy 2saving efficiency is ach ieved w ith the deflecting beam pump ing unit 1
Key words :beam pump ing unit :energy 2saving ;indicati on ;comparison ;efficiency
79Correlative Analysis of Casi ng D estructive Testi ng under Co m plicated L oads
ZHANG X i 2b in (J iang han P etroleum Institu te ,J ing z hou 434102)
Abstract :Casing destructive testing data are analyzed co rrelatively under comp licated loads by using a co rrelative analytical m ethod 1T he result indicates that outside diam eter and w all th ickness are tw o key facto rs influencing the casing radial li m it loading capacity ,the effect of outside casing squeeze p ressure on its axial li m it loading capacity is very big ,the only effect of elli p ticity on casing destructi on caused by even outer squeeze p ressure is h igher 1
Key words :casing failure ;radial fo rce ;axial fo rce ;p ressuring capacity ;experi m ental data ;influencing facto r ;co rrelative analysis
81Exper i m en t al Study of a New Phase -change Ther mal Storage M ater i al
L I N Yi 2hu i ,ZHANG Zhe ng 2guo ,WANG S h i 2p ing (S ou th Ch ina U n iversity of T echnology ,Guang z hou 510640)
Abstract :A new m ethod ,by w h ich nanocompo siti on is m ade up of an o rganic phase 2change ther m al sto rage m aterial w ith an ino rganic m aterial of h igh ther m al conducti on coefficient ,w ould eli m inate the sho rtcom ings of the o rganic energy sto rage m aterial available ,such as liquid leakage ,low heat transfer ,vo lum e changes in phase transiti on ,
?
?
flamm ability ,side effect to the parent m aterial and as w ell as co rro sivity ,overcoo ling and reacting in phase transiti on of the ino rganic ther m al sto rage m aterial 1O rganic 2ino rganic nanocompo siti onal phase 2change ther m al sto rage m aterials are p repared by em bedding the o rganic phase 2change m aterial into a silicon di oxide nano space w ith h igher ther m al conductive facto rs 1T he p repared m aterials are analyzed w ith SE M ,I R ,differential scanning calo ri m eter and ther m al conductivity analyzer 1T he result show s that the compo siti onal phase 2change m aterials are po rous nanocompo siti onal ones ,of w h ich ther m al sto rge capacity and ther m al conductivity are good 1
Key words :compo siti onal m aterial ;phase transiti on ;latent heat ;ther m al sto rage ;ther m al conductivity ;nanom aterial 84I nvok i ng M AT LAB Eng i ne under C ++Builder Env ironm en t
N I X ia o 2ling ,L I U S he ng 2li (J iang han P etroleum Institu te ,J ing z hou 434102)
Abstract :T he fact of invok ing M A TLAB engine under C ++Builder environm ent is that M A TLAB is used as a server 1W hen certain M A TLAB functi on o r comm and is called by an app licati on ,M A TLAB is started up and A ctive X Channel is set up by the engine functi on first ,and then the comm and o r functi on is sent to M A TLAB th rough A ctive X Channel and perfo r m ed by M A TLAB on background ,thus great convenience is p rovided fo r softw are developm ent by using available resources 1
Key words :C ++language ;M A TLAB softw are package ;engine ;channel ;link ing library ;coursew are
86Selection and Opti m ization of M ulticen tre Extre m ity Knee -m echan is m
SHUA I Yu 2m e i ,XU Zha n ,L I S h i 2z he n ,L I U Xu 2hu i (J iang han P etroleum Institu te ,J ing z hou 434102)
Abstract :A cco rding to the design requirem ents of the low er 2extrem ity knee 2m echanis m of hum an body ,a p lain four 2bar m echanis m is selected as a m ulticentre knee 2m echanis m ,and the know ledge concerning m echanical p rinci p les is used to analyze the movem ent of the m echanis m 1Further mo re ,a m athem atical model fo r the m echanis m is established ,and the comp lex shape m ethod is used to derive a group of the best so luti ons in a five 2di m ensi onal design space ,by w h ich a m ini m al erro r betw een real value and ideal value of the instant center coo rdinate required by target functi on is ach ieved ,that is the real instant center curve of the m echanis m is consistent w ith the ideal centrode ,so as to p rove that the designed knee 2m echanis m w ould m eet the requirem ents of design better 1
Key words :bi onic device ;extrem ity 2knee ;m echanis m of connecting rod ;shape selecti on ;op ti m izing design
89A Fault Check i ng I n stru m en t for 10kV L i ne to Ground L I U Ha o 2yu ,J I N C ha ng 2x ing (Cheng d e P etroleum Colleg e ,Cheng d e 067000)
Abstract :A p ractical instrum ent is developed fo r quick ly check ing out the ground po int of a 10kV pow er line 1T he feature of the instrum ent is to use the earth po int of 10kV pow er line to em it har monic component of 5ti m es to the surrounding w ith the h ighest p ropo rti on ,if a double T filtrati on netw o rk is adop ted ,the har monic source of 5ti m es is checked ,the earth po int of the pow er line is found out 1
Key words :h igh vo ltage pow er line ;earth ;fault check ;fault detecto r
91Non li near Programm i ng Proble m s i n Grey Syste m ZHANG S hu 2hong ,XU Zh i 2yun ,CHEN M ia n 2yun ,SONG Ye 2x in (H uaz hong U n iversity of S cience &T echnology ,W uhan 430074)
Abstract :A discussi on is m ade on L agrange m ethod fo r nonlinear p rogramm ing p roblem s ,including unconstrained grey nonlinear p rogramm ing ,constrained grey nonlinear p rogramm ing and nonlinear p rogramm ing in a grey system 1A nalytical m ethods are given fo r so lving vari ous p roblem s of grey nonlinear p rogramm ing 1
Key words :grey system ;nonlinear p rogramm ing ;analytical so luti on
94I m prove m en t i n L i Chu -m i n A lgor ith m by Usi ng an I nher it ance Strategy HUANG W e n 2q i ,WANG L e i (H uaz hong U n iversity of S cience &T echnology ,W uhan 430074)
Abstract :A p reli m inary study is carried out on a strict algo rithm fo r so lving SA T p roblem s by using inheritance strategy 1T he strict algo rithm ,w h ich w as put fo r w ard by L i Chu 2m in in 1997,is i m p roved w ith the strategy 1Speed of the i m p roved algo rithm increases about 5%1
Key words :conjunctive no r m alfo r m ;satisfiability ;inheritance strategy ;algo rithm
96Study on M olecular Topolog ical I ndex of Organ ic Co m pound QSPR ——Physical and Che m ical Study of Saturated Cha i n Hydrocarbon
MAO Zhe n ,CHEN W u ,M E I P ing ,M E I B o 2w e n (J iang han P etroleum Institu te ,J ing z hou 434102)
Abstract :T he concep t of a distance derivative m atrix is put fo r w ard based on the adjacency m atrix and distance m atrix of mo lecular graph 1A cco rding to it a new topo logical index M c is established ,w h ich is app lied to study Q SPR in saturated hydrocarbon w ith a satisfied result 1Compared w ith o ther topo logical index ,M c is of obvi ous physical significance w ith excellent structural coherence and selectivity 1T he m ethod is si m p le fo r calculati on 1
Key words :saturated chain hydrocarbon ;structure 2p roperty co rrelati on ;topo logical index
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