JP2004205151A

JP2004205151A - Heat radiation control method for heat accumulator

Info

Publication number: JP2004205151A
Application number: JP2002376691A
Authority: JP
Inventors: Kenji Saida; 健二才田; Makoto Tani; 信谷
Original assignee: Kansai Electric Power Co Inc; Sumika Plastech Co Ltd
Current assignee: Kansai Electric Power Co Inc; Sumika Plastech Co Ltd
Priority date: 2002-12-26
Filing date: 2002-12-26
Publication date: 2004-07-22
Anticipated expiration: 2022-12-26
Also published as: JP4195283B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiation control method with higher repeated stability in starting solidification in a heat accumulator formed by using a heat storage material containing a compound indicating an overcooled state. <P>SOLUTION: This heat radiation control method for the heat accumulator formed by using the heat storage material containing the compound indicating the overcooled state and having at least two pairs of electrodes comprises a step for performing the solidification of the heat storage material by applying a voltage to the first pair of electrodes coming into contact with the heat storage material when the heat storage material is in a molten state and by applying a voltage to the second pair of electrodes coming into contact with the heat storage material in the state of the heat storage material in the overcooled state brought into contact with the first pair of electrodes and a step for performing the solidification of the heat storage material by applying a voltage to the second pair of electrodes coming into contact with the heat storage material when the heat storage material is in a heated fused molten state and by applying a voltage to the electrodes other than the second pair of electrodes coming into contact with the heat storage material in the state of the overcooled heat storage material coming into contact with the second pair of electrodes. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は建造物の暖房等に用いられる蓄熱装置の放熱制御方法に関する。
【０００２】
【従来の技術】
過冷却状態を示す化合物を含有する蓄熱材を用いてなる蓄熱装置は、料金の割安な深夜電力を用いて発生させた熱を蓄熱材に蓄え、昼間に蓄熱材から熱を徐々に放出させて暖房を行う暖房装置として用いられている。
【０００３】
過冷却状態を示す化合物としては通常は硫酸ナトリウム１０水塩、リン酸水素二ナトリウム１２水塩、酢酸ナトリウム３水塩などの塩水和物が用いられている。これらの塩水和物は、液相から固相への変化に伴う発熱量（凝固熱）が大きく、かつ暖房用に適当な相変化温度すなわち融点を有しているので蓄熱材として好適であるが、過冷却度が大きいという特徴がある。すなわち、融点以下まで温度が低下しても固化が生じないため潜熱の放熱が行われず、このままでは暖房として機能しないことがあるので、この過冷却度が大きいということはこれまで塩水和物の欠点とみなされ、過冷却防止剤の探索が長くなされてきた。
【０００４】
しかし、この過冷却度が大きいことは、外部から過冷却の解除（固化の開始）を制御することにより放熱時期を選ぶこと（このような制御を、以下、「放熱制御」と称することがある。）ができるという点では有利であり、例えば放熱させたいときに種結晶を添加して固化を開始させることにより放熱を開始させる蓄熱装置は古くから提案されている。しかし、種結晶を繰り返し添加することによって蓄熱材の組成が変化することや、添加操作が頻繁な場合は煩雑であり実用的でないことなどの問題点があった。
【０００５】
そこで、より簡便な放熱制御方法として、過冷却状態を示す酢酸ナトリウム３水塩を蓄熱材として用いてなる蓄熱装置において、該蓄熱材に１対の銅−アマルガム電極を挿入し、過冷却状態で２．５Ｖの直流電圧を印加して固化させる放熱制御方法が提案されている（例えば、特許文献１参照。）。しかしながら、この方法は、固化開始の繰り返し安定性に乏しいという問題点があった。
【０００６】
そこで、この問題を解決するために、厚さ０．０１〜０．２ｍｍの銀箔のテープを銀の棒に巻きつけた積層または巻回構造の電極が提案されている（例えば、特許文献２参照。）。この電極を用いる放熱制御方法は、電圧印加の度に電極の表面に形成されていく酸化皮膜が自然に剥落して新しい表面が生成され、電圧印加時にはその新しい表面から過冷却状態の蓄熱材の固化が始まるので、固化開始の繰り返し安定性が保持できるという機構を有するが、酸化皮膜が自然に剥落しなければ該機構が作用することがないため、固化開始の繰り返し安定性が従来より一層高い放熱制御方法が望まれていた。
【０００７】
【特許文献１】
特開昭５７−１７４６９３号公報
【特許文献２】
特開平８−５２７６号公報
【０００８】
【発明が解決しようとする課題】
本発明は前記した従来技術の問題点を解決しようとするものである。本発明の目的は、過冷却状態を示す化合物を含有する蓄熱材を用いてなる蓄熱装置において、固化開始の繰り返し安定性が従来より一層高い放熱制御方法を提供することである。
【０００９】
【課題を解決するための手段】
本発明者は、過冷却状態を示す化合物を含有する蓄熱材を用いてなり、少なくとも２対の電極を備えた蓄熱装置の放熱制御方法について鋭意検討し、蓄熱装置の少なくとも２対の電極への電圧の印加と蓄熱材の固化を特定の手順で行うことにより、固化開始の繰り返し安定性が従来より一層高い放熱制御が行えることを見出し、本発明を完成させるに至った。
【００１０】
すなわち本発明は、過冷却状態を示す化合物を含有する蓄熱材を用いてなり、少なくとも２対の電極を備えた蓄熱装置において、該蓄熱材が溶融状態のときに蓄熱材に接触した第１対の電極に電圧を印加し、次に過冷却状態とした蓄熱材に第１対の電極を接触させた状態で蓄熱材に接触した第２対の電極への電圧の印加により蓄熱材の固化を行う手順と、蓄熱材が加熱溶融状態のときに蓄熱材に接触した第２対の電極に電圧を印加し、次に過冷却状態とした蓄熱材に第２対の電極を接触させた状態で蓄熱材に接触した第２対の電極以外の電極への電圧の印加により蓄熱材の固化を行う手順とを含むことを特徴とする蓄熱装置の放熱制御方法を提供する。
【００１１】
【発明の実施の形態】
以下本発明について詳しく説明する。
まず、本発明の放熱制御方法について以下に述べる。
本発明の放熱制御方法は、過冷却状態の蓄熱材に接触する１対の電極への電圧印加により、過冷却状態を解除して固化を開始させる放熱制御方法に関する方法である。この放熱制御方法において、安定的に固化を開始させるには、次に述べる通電処理と固化処理をこの順で共に行う電極活性化処理が必要である。
すなわち、まず、本発明における蓄熱装置の蓄熱材を融点以上に加熱して融解液とし、これに接触した第１対の電極に、蓄熱材が融解液（温度は融点以上）となっているときに電圧を印加して通電することにより通電処理を行う。通電処理において電極に印加する電圧は通常は１〜３Ｖ程度、好ましくは１〜１．５Ｖである。通電時間は通常は０．１時間以上、好ましく１〜８時間程度である。そして次に、固化処理を行う。蓄熱材が融点以上の場合は冷却して融点以下とし、少なくとも１本（第１対の片側）の電極が蓄熱材に接触した状態で過冷却状態の蓄熱材を固化させ、電極表面と結晶（固化した蓄熱材）を接触させる。これを固化処理と称する。
【００１２】
この通電処理と固化処理をこの順で共に行うことにより、電極の活性化処理がなされ、過冷却状態の蓄熱材に接触する第１対の電極への電圧印加により、過冷却状態を解除して固化を開始させることができるようになる。しかし、電極のこの活性化処理の効果の持続回数には限度があり、限度の回数を超えると、過冷却状態の蓄熱材の固化を、第１対の電極への電圧の印加により安定的には開始させることができなくなる。
【００１３】
そこで、本発明の放熱制御方法においては、少なくとも２対の電極を備えた蓄熱装置を用い、第１対の電極により安定的に固化が行える限度の固化の回数範囲内において第１対の電極を用いて蓄熱装置の運転を行った後、蓄熱材が溶融状態のときに蓄熱材に接触した第１対の電極に電圧を印加して通電処理を行い、次に過冷却状態とした蓄熱材に第１対の電極の少なくとも片側を接触させた状態で、蓄熱材に接触した第２対の電極への電圧の印加により蓄熱材の固化を行うことにより固化処理を行い、第１対の電極の活性化処理を行う手順を実施する。さらに、通常は第２対の電極により安定的に固化が行われる限度内において第２対の電極を用いて蓄熱装置の運転を行った後、蓄熱材が溶融状態のときに蓄熱材に接触した第２対の電極に電圧を印加して通電処理を行い、次に過冷却状態とした蓄熱材に第２対の電極の少なくとも片側を接触させた状態で、蓄熱材に接触した第２対以外の電極（第１対または第３対）への電圧の印加により蓄熱材の固化を行うことにより固化処理を行い、第２対の電極の活性化処理を行う手順を実施する。
【００１４】
さらに同様の手順を続けていけば、第ａ対の電極により安定的に固化が行われる限度内において第ａ対の電極を用いて蓄熱装置の運転を行った後、蓄熱材が溶融状態のときに蓄熱材に接触した第ａ対の電極に電圧を印加して通電処理を行い、次に過冷却状態とした蓄熱材に第ａ対の少なくとも片側の電極を接触させた状態で第ａ対以外のいずれかの蓄熱材に接触した電極に電圧を印加して蓄熱材の固化を行うことにより固化処理を行い、第ａ対の電極の活性化処理を行う手順を実施する。このように本発明は、少なくとも２対の電極を用いて順次電極の活性化処理を行うことにより、固化開始の繰り返し安定性が従来より一層高い放熱制御を行うことができるのである。
【００１５】
次に、本発明の放熱制御方法の手順をＡ対とＢ対の２対の電極を用いた場合についてさらに詳細に説明する。
（１）まず、Ａ対電極を用いて蓄熱装置を運転する。電力、温水などによって蓄熱材の融点以上に加熱して蓄熱材を融解状態とする（蓄熱材に蓄熱された状態となる。）。加熱を停止すると蓄熱材は冷却されて融点以下となる（蓄熱材は過冷却状態となる。）。放熱を所望する時刻にＡ対電極に電圧を印加するとＡ対電極から結晶（固化した蓄熱材）が析出し、蓄熱材が固化に至る。このとき放熱される（蓄熱材は放熱された状態となる。）。この蓄熱−過冷却−放熱のサイクルを１〜ｎ回繰り返して蓄熱装置の蓄熱−放熱の運転を行う。ｎはＡ対電極の繰り返し限度の回数より少ない数である。
【００１６】
（２）次に、Ａ対電極の活性化処理をＢ対電極を用いて行う手順を説明する。１〜ｎ回後の蓄熱材が融解状態のときに、Ａ対電極に電圧を印加する。これは前記活性化処理の通電処理であり、前記同様の条件で行う。次に蓄熱材を冷却して過冷却状態とし、放熱を所望する時刻にＢ対電極に電圧を印加するとＢ対電極から結晶が析出し、蓄熱材が固化する。これによってＡ対電極に対する固化処理が実施されたことになる。
【００１７】
（３）このあと、Ｂ対電極を用いて蓄熱−過冷却−放熱のサイクルを１〜ｍ回繰り返して蓄熱装置の蓄熱−放熱の運転を行う。ｍはＢ対電極の繰り返し限度の回数より少ない数である。
【００１８】
（４）次に、Ｂ対電極の活性化処理をＡ対電極を用いて行う手順を説明する。１〜ｍ回後の蓄熱材が融解状態のときに、Ｂ対電極に電圧を印加する。これはＢ対電極に対する通電処理である。次に蓄熱材を冷却して過冷却状態とし、放熱を所望する時刻にＡ対電極に電圧を印加すると、Ａ対電極から結晶が析出して蓄熱材が固化して、Ｂ対電極の固化処理が実施される。
【００１９】
（５）以下、Ａ対−Ｂ対−Ａ対−…のようにＡ対とＢ対電極を交互に用いる。このように安定的に固化が行える限度の固化の回数範囲内において、電極を活性化しながら用いることによって、極めて長期にわたり安定的に放熱制御が行えるのである。
【００２０】
なお、蓄熱装置の初回の運転開始前に、各新電極の活性化処理を、例えば、次のようにして行っておく必要がある。
本発明における蓄熱装置の蓄熱材を融点以上に加熱して融解液とし、これに１本以上の新電極を挿入し、必要であれば他の対向電極（前記１本以上の電極に＋の電位が印加される場合、−の電位が印加される電極のこと。）も挿入して電圧を印加して通電する。電圧は通常は１〜３Ｖ程度、好ましくは１〜１．５Ｖである。通電時間は０．１時間以上、好ましくは１〜８時間程度である。この通電処理によって新電極表面が一部溶出して新たな表面が形成されるものと思われる。次に固化処理を行う。蓄熱材を冷却して融点以下とすると、過冷却状態となる。この状態で蓄熱材を固化させ、前記固化処理を行った新電極表面と結晶（固化した蓄熱材）を接触させる。固化の方法は、種結晶を添加する、先鋭物を挿入する、液表面を乾燥させるなどいずれでもよい。このように通電処理と固化処理をこの順で共に行うことで新電極の活性化処理が実現される。この活性化処理は蓄熱材の充填された容器で行われてもよいし、別途準備された前処理装置で行われてもよい。後者の場合は活性化処理の済んだ電極を蓄熱材が充填された容器に移して固定して蓄熱装置に設置する。
【００２１】
続いて、本発明における蓄熱装置について説明する。
本発明の蓄熱装置は加熱・冷却によって固液相変化を呈する酢酸ナトリウム３水塩、リン酸水素二ナトリウム１２水塩、硫酸ナトリウム１０水塩などの塩水和物を主材として含有する蓄熱材を用いてなる。該蓄熱材は通常、透湿性のない容器に充填して用いることが好ましい。容器の形状は特に限定されず、円筒状、コイル状、平板状など任意の形状のものを用いることができる。蓄熱材を充填した容器が床内部に埋設されて使用される場合には、荷重に耐える十分な強度を有することが好ましい。
【００２２】
蓄熱材には塩水和物以外に水と固液分離防止剤とを含有させることができる。水の量は、塩水和物の水和モル数の１／３程度以下である。固液分離防止剤としては、水溶性高分子、水膨潤性高分子、高吸水性樹脂、シリカ系増粘剤などが挙げられる。水溶性高分子としてはポリアクリル酸ナトリウム、ポリアクリルアミド、天然ガム類などが挙げられる。水膨潤性高分子としては架橋ポリアクリル酸ナトリウムなどが挙げられる。高吸水性樹脂としては架橋ポリアクリル酸塩、架橋ポリビニルアルコールなどが挙げられる。シリカ系増粘剤としては、煙霧状シリカなどが挙げられる。さらに融点調整剤、分散剤、消泡剤、腐食防止剤、着色剤などを含有させることができる。
【００２３】
また、本発明の活性化方法を用いることができる蓄熱装置は少なくとも２対の電極を備え、各１対の電極の少なくとも１本は銀電極であることが好ましい。銀電極とは、蓄熱材に接触しうる導電性部分の少なくとも一部が銀または銀合金からなるものをいう。もう片方の電極は鉛、銅、亜鉛、鉄、ニッケル、スズ、炭素などであってもよいが、両方とも銀電極であることがより好ましい。電極の形状は線状、板状、棒状、管状などいかなるものでもよい。電極の数は少なくとも２対を要するが、１対の電極の１本を他の１対の電極と共用することができる。従って、電極総数は偶数でも奇数でもよい。ただし、この場合、共用されていない電極が銀電極であることが好ましい。
【００２４】
ここで、本発明の蓄熱装置は、その蓄熱材を過冷却状態とした後に、その電極に電圧を印加することにより蓄熱材の固化を開始させ、放熱制御を行う。そのときの印加電圧は電極の形状、電極間隔などにも依存するが、通常は０．３〜３Ｖ、好ましくは０．７〜１．５Ｖである。０．３Ｖより低いと安定して固化が開始できないおそれがあり、３Ｖより高いと電極から水素ガスを含んだ気泡が発生することがあるため好ましくない。周波数は直流または交流のいずれでもよく、好ましくは０．００１〜１Ｈｚの交流が用いられる。
【００２５】
【実施例】
以下実施例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。
【００２６】
実施例１
（溶液調製）
酢酸ナトリウム無水物５８．８ｇ、水４６．２ｇを１５０ｍｌビーカーに採取し、６５℃水浴中で加熱して透明な溶液に調製した。これを５０ｍｌスクリュー管に５０ｇ採取し、６２℃水浴中に保持した。
【００２７】
（電極設置）
直径１ｍｍ、長さ６５ｍｍの銀線（純度９９．９重量％）４本（Ａ，Ｂ二対）をゴム栓に挿入したあと、アセトンで洗浄、乾燥した。これを前記のスクリュー管に挿入し、銀線先端５ｍｍが溶液に浸漬するように調整した。
【００２８】
（活性化処理）
上記スクリュー管を６２℃水浴中に保持し、電圧１．５Ｖ、周波数０．０５Ｈｚの交流を一対につき４時間通電した。スクリュー管を２０℃水中に浸漬し、１時間後に電極付ゴム栓を取り除いて酢酸ナトリウム３水塩の種結晶数粒を投入し、直ちにゴム栓を挿入した。スクリュー管中の溶液は全体が固化した。これを一夜静置した。
【００２９】
（固化実験）
上記固化した試料を６２℃水浴中に浸漬し、１．５時間後にマグネチックスターラーで２時間攪拌した結果、試料は透明溶液となった。これを２０℃水中に３０分浸漬して過冷却溶液とした。Ａ電極に室温にて電圧１．５Ｖ、周波数０．０５Ｈｚの交流を印加したところ、２２秒後にＡ電極先端から固化が始まり、直ちに全体が固化した。固化した試料を上記同様に６２℃融解し、２０℃で冷却し、室温でＡ電極に電圧印加を行うことを繰り返した。２０回の繰り返しで毎回固化が始まった。続いて６２℃融解し、Ａ電極に電圧１．５Ｖ、周波数０．０５Ｈｚの交流を１時間印加した。これを２０℃水中に３０分浸漬して過冷却溶液とした。Ｂ電極に電圧１．５Ｖ、周波数０．０５Ｈｚの交流を印加したところ、６５秒後にＢ電極先端から固化が始まり、直ちに全体が固化した。
【００３０】
（Ａ電極の活性化）
固化した試料を上記同様に６２℃融解し、２０℃で冷却し、室温でＢ電極に電圧印加を行うことを繰り返した。２０回の繰り返しで毎回固化した。続いて６２℃融解し、Ｂ電極に電圧１．５Ｖ、周波数０．０５Ｈｚの交流を１時間印加した。これを２０℃水中に３０分浸漬して過冷却溶液とした。Ａ電極に電圧１．５Ｖ、周波数０．０５Ｈｚの交流を印加したところ、４７秒後にＡ電極先端から固化が始まり、直ちに全体が固化した。
【００３１】
（Ｂ電極の活性化）
以下２０回毎にＡおよびＢ電極の活性化を行いながら、繰り返し耐久性を調べた。Ａ，Ｂ電極の交替を８回行っても毎回固化した。
【００３２】
比較例１
実施例１と同様にして溶液調製、電極設置、活性化処理を行った。固化した試料について融液時の通電処理をしなかったことを除いて実施例１の固化実験と同様の繰り返し実験を行った。固化回数は、Ａ電極２０回発核→Ａ電極通電処理なし→Ｂ電極２０回固化→Ｂ電極通電処理なし→Ａ電極２０回固化→Ａ電極通電処理なし→Ｂ電極２０回固化→Ｂ電極通電処理なし→Ａ電極１５回固化後に失活、という結果であった。融液時の通電処理をしなかったために電極の活性化が行われず、安定的に放熱制御することができなくなった。
【００３３】
【発明の効果】
本発明の放熱制御方法によれば、過冷却状態を示す液を含有する蓄熱材を用いてなる蓄熱装置は、電圧印加という簡便な操作で放熱時期を制御することが極めて長期にわたって安定的に可能となるため、特に建造物の暖房として用いる場合に極めて長期にわたって安定的な運転が可能であるので、工業的に極めて有用である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for controlling heat radiation of a heat storage device used for heating a building or the like.
[0002]
[Prior art]
A heat storage device using a heat storage material containing a compound showing a supercooled state stores heat generated using late-night electric power at a low price in the heat storage material, and gradually releases heat from the heat storage material in the daytime. It is used as a heating device for heating.
[0003]
As the compound showing a supercooled state, a salt hydrate such as sodium sulfate decahydrate, disodium hydrogenphosphate decahydrate, and sodium acetate trihydrate is usually used. These salt hydrates are suitable as heat storage materials because they have a large calorific value (heat of solidification) accompanying a change from a liquid phase to a solid phase and have a phase change temperature, that is, a melting point, suitable for heating. It is characterized by a large degree of supercooling. That is, even if the temperature is lowered below the melting point, solidification does not occur, so that latent heat is not radiated, and it may not function as heating as it is, so that a large degree of supercooling is a disadvantage of salt hydrates so far. The search for supercooling inhibitors has long been made.
[0004]
However, the fact that the degree of supercooling is large means that heat release timing is selected by externally controlling release of supercooling (start of solidification) (such control may be hereinafter referred to as “radiation control”). ) Can be performed. For example, a heat storage device that starts heat radiation by adding a seed crystal and starting solidification when heat radiation is desired has been proposed for a long time. However, there have been problems such as that the composition of the heat storage material changes due to repeated addition of the seed crystal and that the addition operation is frequent and complicated and impractical.
[0005]
Therefore, as a simpler heat radiation control method, in a heat storage device using sodium acetate trihydrate showing a supercooled state as a heat storage material, a pair of copper-amalgam electrodes is inserted into the heat storage material, and the supercooled state is set. A heat radiation control method for applying a DC voltage of 2.5 V to solidify has been proposed (for example, see Patent Document 1). However, this method has a problem that repetition stability at the start of solidification is poor.
[0006]
Therefore, in order to solve this problem, an electrode having a laminated or wound structure in which a silver foil tape having a thickness of 0.01 to 0.2 mm is wound around a silver bar has been proposed (for example, see Patent Document 2). .). In this method of controlling heat radiation using electrodes, the oxide film formed on the electrode surface spontaneously peels off every time a voltage is applied, and a new surface is generated. When a voltage is applied, the supercooled heat storage material is removed from the new surface. Since the solidification starts, it has a mechanism that can maintain the repeated stability of the start of solidification, but since the mechanism does not work unless the oxide film peels off naturally, the repeated stability of the start of solidification is higher than before. A heat dissipation control method has been desired.
[0007]
[Patent Document 1]
JP-A-57-174693 [Patent Document 2]
JP-A-8-5276
[Problems to be solved by the invention]
The present invention seeks to solve the above-mentioned problems of the prior art. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat dissipation control method in which a heat storage device using a heat storage material containing a compound exhibiting a supercooled state has a higher repetition stability of the start of solidification than in the past.
[0009]
[Means for Solving the Problems]
The inventor of the present invention has made extensive use of a heat storage material containing a compound exhibiting a supercooled state, and has studied the heat release control method of a heat storage device provided with at least two pairs of electrodes. It has been found that by performing voltage application and solidification of the heat storage material in a specific procedure, it is possible to perform heat radiation control with a higher stability of repetition of solidification start than in the past, and completed the present invention.
[0010]
That is, the present invention uses a heat storage material containing a compound exhibiting a supercooled state, and in a heat storage device provided with at least two pairs of electrodes, a first pair which contacts the heat storage material when the heat storage material is in a molten state. A voltage is applied to the first electrode and then the first pair of electrodes is brought into contact with the heat storage material in a supercooled state, and the voltage is applied to the second pair of electrodes that contact the heat storage material to solidify the heat storage material. Performing the procedure and applying a voltage to the second pair of electrodes in contact with the heat storage material when the heat storage material is in the heated and molten state, and then contacting the second pair of electrodes with the heat storage material in the supercooled state. Performing a solidification of the heat storage material by applying a voltage to an electrode other than the second pair of electrodes in contact with the heat storage material.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
First, the heat radiation control method of the present invention will be described below.
The heat radiation control method of the present invention is a method relating to a heat radiation control method in which a supercooled state is released and solidification is started by applying a voltage to a pair of electrodes in contact with a heat storage material in a supercooled state. In this heat radiation control method, in order to start solidification stably, it is necessary to perform an electrode activation process in which the energization process and the solidification process described below are performed together in this order.
That is, first, when the heat storage material of the heat storage device of the present invention is heated to a melting point or higher to form a melt, and the first pair of electrodes in contact with the heat storage material is a melt (temperature is higher than the melting point). The voltage is applied to the power supply and the power is supplied to perform the power supply processing. The voltage applied to the electrodes in the energization process is usually about 1 to 3 V, preferably 1 to 1.5 V. The energization time is usually 0.1 hour or more, preferably about 1 to 8 hours. Then, a solidification process is performed. If the heat storage material is at or above the melting point, it is cooled to the melting point or less, and the supercooled heat storage material is solidified while at least one electrode (one side of the first pair) is in contact with the heat storage material, and the electrode surface and the crystal (Solidified heat storage material). This is called a solidification process.
[0012]
By performing the energization process and the solidification process together in this order, the activation process of the electrodes is performed, and the supercooled state is released by applying a voltage to the first pair of electrodes that contact the heat storage material in the supercooled state. The solidification can be started. However, there is a limit to the number of times that the effect of the activation process of the electrode can be maintained, and when the number of times exceeds the limit, the solidification of the heat storage material in a supercooled state is stably performed by applying a voltage to the first pair of electrodes. Cannot be started.
[0013]
Therefore, in the heat radiation control method of the present invention, a heat storage device having at least two pairs of electrodes is used, and the first pair of electrodes is set within a range of the number of times of solidification that can be stably solidified by the first pair of electrodes. After operating the heat storage device using the heat storage material, when the heat storage material is in a molten state, a voltage is applied to the first pair of electrodes in contact with the heat storage material to perform energization processing, and then the heat storage material in a supercooled state is applied. In a state where at least one side of the first pair of electrodes is in contact, the solidification of the heat storage material is performed by applying a voltage to the second pair of electrodes in contact with the heat storage material, thereby performing a solidification process. The procedure for performing the activation process is performed. Furthermore, after operating the heat storage device using the second pair of electrodes within a limit where the solidification is normally performed by the second pair of electrodes, the heat storage material came into contact with the heat storage material when in a molten state. A current is applied by applying a voltage to the second pair of electrodes, and then the heat storage material in a supercooled state is brought into contact with at least one side of the second pair of electrodes. The solidification process is performed by solidifying the heat storage material by applying a voltage to the first pair of electrodes (first pair or third pair), and the procedure of activating the second pair of electrodes is performed.
[0014]
If the same procedure is continued, after the operation of the heat storage device using the a-th pair of electrodes is performed within the limit that the solidification is stably performed by the a-th pair of electrodes, when the heat storage material is in a molten state A voltage is applied to the a-th pair of electrodes in contact with the heat storage material to perform energization processing, and then at least one electrode of the a-th pair is brought into contact with the heat storage material in a supercooled state. The solidification process is performed by applying a voltage to the electrode in contact with any of the heat storage materials to solidify the heat storage material, and the procedure of activating the a-th pair of electrodes is performed. As described above, according to the present invention, by sequentially activating the electrodes using at least two pairs of electrodes, it is possible to perform heat radiation control with higher repetition stability of the start of solidification than before.
[0015]
Next, the procedure of the heat radiation control method of the present invention will be described in more detail with respect to the case where two pairs of electrodes A and B are used.
(1) First, the heat storage device is operated using the A counter electrode. The heat storage material is heated to a temperature higher than the melting point of the heat storage material by electric power, hot water, or the like to bring the heat storage material into a molten state (a state in which the heat storage material is stored). When the heating is stopped, the heat storage material is cooled down to the melting point or lower (the heat storage material enters a supercooled state). When a voltage is applied to the A counter electrode at a time when heat dissipation is desired, crystals (solidified heat storage material) precipitate from the A counter electrode, and the heat storage material is solidified. At this time, heat is dissipated (the heat storage material is dissipated). This heat storage-supercooling-radiation cycle is repeated 1 to n times to perform the heat storage-radiation operation of the heat storage device. n is a number smaller than the number of repetition limits of the A counter electrode.
[0016]
(2) Next, a procedure for activating the A counter electrode using the B counter electrode will be described. When the heat storage material after 1 to n times is in a molten state, a voltage is applied to the A counter electrode. This is an energization process of the activation process, and is performed under the same conditions as described above. Next, the heat storage material is cooled to a supercooled state, and when a voltage is applied to the B counter electrode at a desired time for heat radiation, crystals precipitate from the B counter electrode and the heat storage material solidifies. This means that the solidification process has been performed on the A counter electrode.
[0017]
(3) Thereafter, the cycle of heat storage / supercooling / radiation is repeated 1 to m times using the B counter electrode to perform the operation of heat storage / radiation of the heat storage device. m is a number smaller than the number of repetition limits of the B counter electrode.
[0018]
(4) Next, a procedure for activating the B counter electrode using the A counter electrode will be described. When the heat storage material after 1 to m times is in a molten state, a voltage is applied to the B counter electrode. This is an energization process for the B counter electrode. Next, the heat storage material is cooled to a supercooled state, and when a voltage is applied to the A counter electrode at a desired time for heat radiation, crystals are precipitated from the A counter electrode and the heat storage material is solidified, thereby solidifying the B counter electrode. Is carried out.
[0019]
(5) Hereinafter, the pair A and the pair B electrodes are used alternately, such as A pair-B pair-A pair-. When the electrodes are used while being activated within the range of the number of times of solidification that can stably solidify, the heat radiation control can be stably performed for an extremely long time.
[0020]
Before the first operation of the heat storage device, the activation process of each new electrode needs to be performed as follows, for example.
The heat storage material of the heat storage device according to the present invention is heated to a melting point or higher to form a molten liquid, and one or more new electrodes are inserted into the molten liquid. If necessary, another counter electrode (a positive potential is applied to the one or more electrodes). Is applied, an electrode to which a negative potential is applied is also inserted, and a voltage is applied to conduct electricity. The voltage is usually about 1 to 3V, preferably 1 to 1.5V. The energization time is at least 0.1 hour, preferably about 1 to 8 hours. It is considered that a part of the surface of the new electrode is eluted by the energization treatment to form a new surface. Next, a solidification process is performed. When the heat storage material is cooled to a temperature equal to or lower than the melting point, a supercooled state occurs. In this state, the heat storage material is solidified, and the crystal (solidified heat storage material) is brought into contact with the surface of the new electrode subjected to the solidification treatment. The method of solidification may be any method such as adding a seed crystal, inserting a sharp object, or drying the liquid surface. By performing the energization process and the solidification process together in this order, the activation process of the new electrode is realized. This activation processing may be performed in a container filled with a heat storage material, or may be performed in a separately prepared pretreatment device. In the latter case, the activated electrode is transferred to a container filled with a heat storage material, fixed and installed in a heat storage device.
[0021]
Next, the heat storage device according to the present invention will be described.
The heat storage device of the present invention comprises a heat storage material mainly containing a salt hydrate such as sodium acetate trihydrate, disodium hydrogen phosphate 12 hydrate, sodium sulfate 10 hydrate which exhibits a solid-liquid phase change by heating and cooling. Used. It is usually preferable to use the heat storage material by filling it in a container having no moisture permeability. The shape of the container is not particularly limited, and any shape such as a cylindrical shape, a coil shape, and a flat plate shape can be used. When the container filled with the heat storage material is used by being buried inside the floor, it is preferable that the container has sufficient strength to withstand a load.
[0022]
The heat storage material may contain water and a solid-liquid separation preventing agent in addition to the salt hydrate. The amount of water is about 1/3 or less of the number of moles of hydrate of the salt hydrate. Examples of the solid-liquid separation inhibitor include a water-soluble polymer, a water-swellable polymer, a superabsorbent resin, and a silica-based thickener. Examples of the water-soluble polymer include sodium polyacrylate, polyacrylamide, natural gums and the like. Examples of the water-swellable polymer include cross-linked sodium polyacrylate. Examples of the superabsorbent resin include a crosslinked polyacrylic acid salt and a crosslinked polyvinyl alcohol. Examples of the silica-based thickener include fumed silica. Further, a melting point adjusting agent, a dispersant, an antifoaming agent, a corrosion inhibitor, a coloring agent, and the like can be contained.
[0023]
Further, the heat storage device that can use the activation method of the present invention includes at least two pairs of electrodes, and at least one of each pair of electrodes is preferably a silver electrode. The silver electrode refers to an electrode in which at least a part of a conductive portion that can contact a heat storage material is made of silver or a silver alloy. The other electrode may be lead, copper, zinc, iron, nickel, tin, carbon, etc., but more preferably both are silver electrodes. The shape of the electrode may be any shape such as a linear shape, a plate shape, a rod shape, and a tubular shape. At least two pairs of electrodes are required, but one of the pair of electrodes can be shared with another pair of electrodes. Therefore, the total number of electrodes may be even or odd. However, in this case, it is preferable that the electrode not shared is a silver electrode.
[0024]
Here, the heat storage device of the present invention starts the solidification of the heat storage material by applying a voltage to the electrode after the heat storage material is set in a supercooled state, and performs heat release control. The applied voltage at that time depends on the shape of the electrodes, the electrode spacing, and the like, but is usually 0.3 to 3 V, preferably 0.7 to 1.5 V. If the voltage is lower than 0.3 V, solidification may not be started stably, and if the voltage is higher than 3 V, bubbles containing hydrogen gas may be generated from the electrode, which is not preferable. The frequency may be either direct current or alternating current, and preferably an alternating current of 0.001 to 1 Hz is used.
[0025]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0026]
Example 1
(Solution preparation)
Anhydrous sodium acetate (58.8 g) and water (46.2 g) were collected in a 150 ml beaker and heated in a 65 ° C. water bath to prepare a clear solution. 50 g of this was collected in a 50 ml screw tube and kept in a 62 ° C. water bath.
[0027]
(Electrode installation)
Four silver wires (two pairs of A and B) having a diameter of 1 mm and a length of 65 mm (purity 99.9% by weight) were inserted into a rubber stopper, washed with acetone, and dried. This was inserted into the screw tube, and adjusted so that the tip of the silver wire 5 mm was immersed in the solution.
[0028]
(Activation process)
The screw tube was kept in a water bath at 62 ° C., and alternating current at a voltage of 1.5 V and a frequency of 0.05 Hz was applied to each pair for 4 hours. The screw tube was immersed in water at 20 ° C., and after 1 hour, the rubber stopper with the electrode was removed, several seed crystals of sodium acetate trihydrate were introduced, and the rubber stopper was inserted immediately. The entire solution in the screw tube solidified. This was left overnight.
[0029]
(Solidification experiment)
The solidified sample was immersed in a water bath at 62 ° C. and stirred 1.5 hours later with a magnetic stirrer for 2 hours. As a result, the sample became a transparent solution. This was immersed in water at 20 ° C. for 30 minutes to obtain a supercooled solution. When an alternating current having a voltage of 1.5 V and a frequency of 0.05 Hz was applied to the A electrode at room temperature, solidification started from the tip of the A electrode 22 seconds later, and the entire solidified immediately. The solidified sample was melted at 62 ° C. in the same manner as described above, cooled at 20 ° C., and voltage application to the A electrode was repeated at room temperature. Solidification started every time after 20 repetitions. Subsequently, the mixture was melted at 62 ° C., and an AC voltage of 1.5 V and a frequency of 0.05 Hz was applied to the A electrode for 1 hour. This was immersed in water at 20 ° C. for 30 minutes to obtain a supercooled solution. When an AC voltage of 1.5 V and a frequency of 0.05 Hz was applied to the B electrode, solidification started from the tip of the B electrode 65 seconds later, and the whole was immediately solidified.
[0030]
(Activation of A electrode)
The solidified sample was melted at 62 ° C. in the same manner as described above, cooled at 20 ° C., and applying a voltage to the B electrode at room temperature was repeated. Solidified each time after 20 repetitions. Subsequently, the mixture was melted at 62 ° C., and an alternating current having a voltage of 1.5 V and a frequency of 0.05 Hz was applied to the B electrode for 1 hour. This was immersed in water at 20 ° C. for 30 minutes to obtain a supercooled solution. When an AC voltage of 1.5 V and a frequency of 0.05 Hz was applied to the A electrode, solidification started from the tip of the A electrode after 47 seconds, and the whole was immediately solidified.
[0031]
(Activation of B electrode)
Thereafter, the durability was repeatedly examined while activating the A and B electrodes every 20 times. Even when the A and B electrodes were replaced eight times, they solidified every time.
[0032]
Comparative Example 1
In the same manner as in Example 1, solution preparation, electrode installation, and activation treatment were performed. A repetitive experiment similar to the solidification experiment of Example 1 was performed except that the solidified sample was not subjected to a current-flow treatment at the time of melting. The number of times of solidification is 20 times nucleation of A electrode → No A electrode energization treatment → 20 times of B electrode solidification → No B electrode energization treatment → 20 times of A electrode solidification → No A electrode energization treatment → 20 times of B electrode solidification → B electrode energization No treatment → Inactivation after 15 solidifications of the A electrode. Since the energization treatment was not performed during the melt, the electrodes were not activated, and it was impossible to stably control the heat radiation.
[0033]
【The invention's effect】
According to the heat radiation control method of the present invention, a heat storage device using a heat storage material containing a liquid showing a supercooled state can stably control the heat radiation timing by a simple operation of voltage application for an extremely long time. In particular, when used for heating a building, stable operation can be performed for an extremely long time, which is extremely useful industrially.

Claims

A heat storage device comprising a heat storage material containing a compound exhibiting a supercooled state, wherein in a heat storage device provided with at least two pairs of electrodes, a voltage is applied to a first pair of electrodes in contact with the heat storage material when the heat storage material is in a molten state. Applying a voltage to a second pair of electrodes in contact with the heat storage material while the first pair of electrodes is in contact with the heat storage material in the supercooled state, and then solidifying the heat storage material; A voltage was applied to the second pair of electrodes in contact with the heat storage material when the material was in the heated and molten state, and then the heat storage material was contacted with the second pair of electrodes in contact with the supercooled heat storage material. A method of solidifying the heat storage material by applying a voltage to an electrode other than the second pair of electrodes.