JP4599804B2

JP4599804B2 - Fuel cell

Info

Publication number: JP4599804B2
Application number: JP2003082416A
Authority: JP
Inventors: 康文高橋; 芳寛西水流
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2003-03-25
Filing date: 2003-03-25
Publication date: 2010-12-15
Anticipated expiration: 2023-03-25
Also published as: JP2004288583A

Description

【０００１】
【発明の属する技術分野】
本発明は、電気化学反応によって発電を行う燃料電池に関し、詳しくは発電反応を行うガスの湿度を調節するためセル構造に関する。
【０００２】
【従来の技術】
従来、この種の燃料電池は、特開平６−１３２０３８号公報に記載されたものが知られている。以下、従来の燃料電池について主に図８、図９、図１０および図１１を参照しながら説明する。なお、説明を解りやすくするため、燃料が水素、酸化剤が空気の場合について説明する。
【０００３】
図８に示すように、電解質部１０１は固体高分子電解質膜１０２を導電性があり触媒が塗られた拡散層１０３で挟みつけて構成し、電解質部１０１の一方に溝状の燃料ガス流路１０４が形成された導電性の燃料ガスセパレータ１０５、他方に溝状の酸化剤ガス流路１０６が形成された導電性の酸化剤ガスセパレータ１０７が配するが、ここで用いられる溝状の流路は断面図に示すように深さ１ｍｍ程の溝である。また、拡散層１０３の周辺はシール材１０８で囲まれている。
【０００４】
次に、図９に示すように電解質部１０１を燃料ガスセパレータ１０５と酸化剤ガスセパレータ１０７とで挟みつけて構成された単セル１０９ａ〜１０９ｊを集電板ａ１１０と集電板Ｂ１１１の間に積層し、これを絶縁板ａ１１２と絶縁板Ｂ１１３で挟み、その両端を更に端板ａ１１４と端板Ｂ１１５で挟みつけ積層体１１６を構成する。そして、図１０に示すように積層体１１６の積層方向には端板Ａ１１４から積層方向他端の集電板Ｂ１１１まで貫通するよう酸化剤ガス供給ヘッダー１１９と、酸化剤ガス排出ヘッダー１２０と、燃料ガス供給ヘッダー１１７と、燃料ガス排出ヘッダー１１８が設けてある。この燃料ガス供給ヘッダー１１７と燃料ガス排出ヘッダー１１８は図３１で示されるように、燃料ガスセパレータ１０５の燃料ガス流路１０４の溝を介して連通されている。さらに、酸化剤ガス供給ヘッダー１１９が燃料ガス供給ヘッダー１１７同様に、酸化剤ガス排出ヘッダー１２０が燃料ガス排出ヘッダー１１８同様に設けてあり、この酸化剤ガス供給ヘッダー１１９と酸化剤ガス排出ヘッダー１２０とは図１１で示されるように、酸化剤ガスセパレータ１０７の酸化剤ガス流路１０６の溝を介して連通している。
【０００５】
つぎに動作について説明する。燃料ガス供給ヘッダー１１７から積層体１１６内に送り込まれた水素は単セル１０９ａ〜１０９ｊにある燃料ガスセパレータ１０５の燃料ガス流路１０４を通って燃料ガス排出ヘッダー１１８から積層体１１６外へ排出される。また、酸化剤ガス供給ヘッダー１１９から積層体１１６内に送り込まれた空気は単セル１０９ａ〜１０９ｊの酸化剤ガスセパレータ１０７の酸化剤ガス流路１０６を通って、酸化剤ガス排出ヘッダー１２０から積層体１１６外へ排出される。
【０００６】
この時、電解質部１０１の燃料ガス流路１０４を流れる水素は一部イオンとなって固体高分子電解質膜１０２を通過して酸化剤ガス流路１０６側に達し、この酸化剤ガス流路１０６を流れる空気中の酸素と反応して水となる。また、酸化剤ガス流路１０６で生成された水の一部は固体高分子電解質膜１０２を浸透して燃料ガス流路１０４に移動する。そしてこのとき燃料ガスセパレータ１０５と酸化剤ガスセパレータ１０７間に直流電圧が生じ、この直流電圧を積層された単セル１０９ａ〜１０９ｊの数だけ加えた直流電圧が集電板Ａ１１０と集電板Ｂ１１１間から取り出される。
【０００７】
【特許文献１】
特開平６−１３２０３８号公報（第２頁、第２図）
【特許文献２】
特開平６−６８８９６号公報（第３−４頁、第１−３図）
【０００８】
【発明が解決しようとする課題】
このような従来の燃料電池では、固体高分子電解質膜は十分な水分を含有することができないため、供給される燃料もしくは酸化剤を加湿することで燃料電池内に水分を供給する方法が一般的であり、別途にバブリングや水噴霧などの加湿器を必要としてコストアップの要因となっていた。また、燃料電池のセルと加湿器が別々の設置時には、加湿される流体は加湿器と燃料電池の本体内および両者の間で分流と合流を繰り返し複雑な流路のために圧力損失が生じ、燃料電池にガスを供給するためのガス供給機器の動力が大きくなるという課題があり、簡単な構成かつ低圧損となるシステム構成が出来る燃料電池が要求されている。
【０００９】
また、燃料電池に加湿したガスを供給すると燃料電池本体で発電反応により生成された水分が燃料電池内で結露して流路を閉塞する。さらに、燃料電池内を流れるガスは発電反応により水分が生成されるため流路の上流側と下流側では湿度が異なり電解質部で水分分布が不均一になり、ガスの流れが乱れ発電反応が不安定になるという課題があり、セル内の発電反応により生成される水分による結露を防ぐと共に均一な湿度を保つ燃料電池が要求されている。
【００１０】
また、特開平６−６８８９６号公報に記載の燃料電池のように、単セルを構成する燃料ガスセパレータおよび酸化剤ガスセパレータと電解質部をその両端において所定の長さ延長し、延長した部分を透過膜として、一方の延長部分に燃料ガスの加湿部、他方の延長部分に酸化剤ガスの加湿部を設け、それぞれのガス加湿部において、一方のガスセパレータに構成されたガス流路と他方のガスセパレータに構成された水補給通路を電解質部を挟んで接触させる構成とし、水補給通路から水分を他方のガスセパレータ上のガス流路内を流れるガスに移行させることで加湿を行う方法が提案されているが、このような構成では燃料電池に供給するガスを加湿するために外部から水分を供給する必要があり、燃料電池が発電する際に発生する反応熱を冷却水などにより回収し、外部の熱を利用する機器などに供給するコージェネレーションシステムなどに燃料電池を利用する場合、水分が蒸発する際に熱を奪うことでシステム全体での熱効率が低下するという問題があった。
【００１１】
本発明は、このような従来の課題を解決するものであり、燃料電池を運転する際に別途加湿器などを設ける必要が無く、分流などによる圧力損失を低減し、発電反応により生成した水分による流路の閉塞防止および均一な湿度維持により、燃料電池の安定動作と発電効率を維持することのできる燃料電池を提供することを目的としている。
【００１２】
【課題を解決するための手段】
本発明の燃料電池は上記目的を達成するために、燃料及び酸化剤の一方である第1反応ガスと燃料及び酸化剤の他方である第２反応ガスとの電気化学反応によって発電を行うセルを備えた固体高分子型燃料電池において、固体高分子電解質膜の両面に触媒を設けた拡散層を有し、発電反応を行う反応部と、反応部と同一面上に配置され、固体高分子電解質膜を介して水分の移動を行う水回収部と、反応部及び水回収部の一方の面に第１反応ガスを流すための第１反応ガス流路と、反応部の他方の面に第２反応ガスを流すための第２反応ガス流路と、水回収部の他方の面に第１反応ガスを流すための加湿流路と、第１反応ガス流路及び加湿流路を高分子電解質膜を介して連結する第１反応ガス移行流路と、を備え、加湿流路を流れる第１反応ガスは、水回収部で加湿された後に第１反応ガス移行流路を通り第１反応ガス流路へ流れ、第１反応ガス流路を流れる第１反応ガスは、反応部での発電反応による水分発生後に水回収部で除湿されることを特徴とするものである。
【００１３】
本発明によれば、別途に加湿器を必要とせず、加湿のための燃料電池への給水および燃料電池の反応熱を必要としないため熱をコージェネレーションシステムなどに有効利用することができ、反応部が発電反応を行う際に生じる熱により水回収部が保温されることにより加湿能力向上と結露を防止しすることができ、反応部と水回収部が最短で結ばれてガスの分流や合流による圧力損失を抑えてガスの供給機器の動力を低減することができる燃料電池が得られる。
【００１４】
また、他の手段は燃料電池の発電を行う反応部に用いられるイオン交換膜を水回収部の透湿膜としても用い、同一の材料を用いたものである。
【００１５】
本発明によれば、セルの構成が簡単になり、材料、製造においてコストダウンが可能となる燃料電池が得られる。
【００１８】
また、他の手段は、第１反応ガス流路は、反応部及び水回収部を交互に流れる経路を備え、第１反応ガス流路を流れる第１反応ガスは、反応部での発電反応による水分の発生と水回収部での除湿を交互に繰り返すことを特徴とするものである。
【００１９】
本発明によれば、発電反応により生成された水分を反応の途中で除湿する構成とすることより反応部の全域で高湿度でありながら結露の無い燃料または酸化剤による発電反応が可能となる燃料電池が得られる。
【００２０】
また、他の手段は、第１反応ガス流路を流れる第１反応ガスは、反応部での発電反応による水分発生後に水回収部で除湿され、再度反応部に流入し、反応部での発電反応による水分発生後に水回収部で除湿されることを特徴とするものである。
【００２１】
本発明によれば、１組の反応部と水回収部により反応部で生成された水分を都度に水回収部で除湿することができ一定の湿度に保つことができる燃料電池が得られる。
また、他の手段は、第１反応ガスを流通するための溝状の第1反応ガス流路が形成された導電性の第1セパレータと、第１反応ガスを流通するための溝状の加湿流路、及び、第２反応ガスを流通するための溝状の第２反応ガス流路が形成された導電性の第２セパレータと、をさらに有しており、反応部及び水回収部は、第１セパレータ及び第２セパレータの間に配置されており、第1セパレータ及び第２セパレータは、第1反応ガスの供給するための第1反応ガス供給孔と、第1反応ガスの排出するための第1反応ガス排出孔と、第２反応ガスの供給するための第２反応ガス供給孔と、第２反応ガスの排出するための第２反応ガス排出孔と、を有し、第1反応ガス供給孔及び第1反応ガス移行流路は、加湿流路によって繋がっており、第1反応ガス移行流路及び第1反応ガス排出孔は、第1反応ガス流路によって繋がっており、第２反応ガス供給孔及び第２反応ガス排出孔は、第２反応ガス流路によって繋がっていることを特徴とするものである。

【００２２】
【発明の実施の形態】
本発明は、燃料および酸化剤となるガスの電気化学反応によって発電を行うセルを備えた燃料電池において、前記セル内で発電反応によって生成した水分を前記セルに供給する前記ガスに回収する水回収部を設けたものであり、セルに送るガスの加湿装置を別途に必要とせず加湿されたガスを発電を行う反応部に送ることができ、加湿のために燃料電池に外部から給水を不用とし、水の気化のために燃料電池の反応熱を用いることなくコージェネレーションシステムなどに有効利用でき、セル内に形成されるため水回収部での結露を防ぐという作用を有する。また、セル内で発電反応の途中で反応によって生成した水分を燃料および酸化剤となるガスへと回収する水回収部を設けたものであり、反応により生成した水分により加湿過多になったガスを除湿することができ、安定した湿度にガスを維持することができるという作用を有する。また、発電反応を行う反応部と、反応により生成した水分を供給される空気に回収するための水回収部が同一面上に設けられたものであり、簡単に反応部と水回収部一体化でき、反応部と水回収部が連続に設けらるためガスの分流が一度で済み、セルの厚さを変えることがないという作用を有する。また、酸化剤の流れるカソード流路または燃料の流れるアノード流路は発電反応部と水回収部を１度以上往復するものであり、カソード流路またはアノード流路を延長することで反応部で生成した水分を水回収部で除湿するという流路構成を容易に形成できるという作用を有する。また、酸化剤の流れるカソード流路または燃料の流れるアノード流路は発電反応部と水回収部の間を往復する様に折れ曲り部を一つ以上の設けたものであり、カソード流路またはアノード流路をつづら折にすることにより反応部と水回収部の間を容易に往復して酸化剤または燃料を発電反応と除湿が繰り返されて湿度を一定に保つことができるという作用を有する。また、酸化剤の流れるカソード流路または燃料の流れるアノード流路は始めに発電水回収部を通った後に反応部を通るものであり、発電反応前の酸化剤または燃料を必ず加湿できるという作用を有する。また、酸化剤の流れるカソード流路または燃料の流れるアノード流路は最後に水回収部を通るものであり、発電反応が終わった酸化剤または燃料の湿度が最も高いため、供給する空気を効率よく加湿できるという作用を有する。
【００２３】
以下、本発明の実施例について図面を参照しながら説明する。なお、従来例と同一のものは同一番号を付し、その詳細な説明を省略する。また、実施例においては説明を解りやすくするため、燃料は水素を含むガス、酸化剤は空気の場合について説明する。
【００２４】
【実施例】
（実施例１）
図１および図２に示すように、電解質部１０１には発電を行う部分である反応部１と水回収部２が設けられ、反応部１および水回収部２の周辺はシール３で囲まれてある。水回収部２は透湿膜として固体高分子電解質膜１０２が配されたものでガス不透過性を有し水の移動を行うものである。また、反応部１は固体高分子電解質膜１０２の両側に導電性のある触媒を塗布した拡散層１０３を配したものである。そして、電解質部１０１の一方に溝状の酸化剤流路４が形成された導電性の酸化剤セパレータ５を配し、他方に溝状の燃料流路６および加湿流路７が形成された導電性の燃料セパレータ８を配する。酸化剤流路４、燃料流路６および加湿流路７は溝状の流路である。また、電解質部には加湿流路７と酸化剤流路４を繋ぐ酸化剤移行流路９が備えてある。
【００２５】
次に、図３に示すように電解質部１０１を酸化剤セパレータ５と燃料セパレータ８で挟みつけて構成された単セル１０ａ〜１０ｊを集電板Ａ１１０と集電板Ｂ１１１の間に積層し、これを絶縁板Ａ１１２と絶縁板Ｂ１１３で挟み、その両端を更に端板Ａ１１４と端板Ｂ１１５で挟みつけ積層体１１を構成する。そして、図４に示すように積層体１１の積層方向には端板Ａ１１４から積層方向他端の集電板Ｂ１１１まで貫通するよう酸化剤ガス供給ヘッダー１１９と、酸化剤ガス排出ヘッダー１２０と、燃料ガス供給ヘッダー１１７と、燃料ガス排出ヘッダー１１８が設けてある。
【００２６】
燃料及び酸化剤の流れる流路を図５および図６に示す、酸化剤ガス供給ヘッダー１１９と酸化剤移行流路９は燃料セパレータ８の加湿流路７により繋がり、酸化剤移行流路９と酸化剤ガス排出ヘッダー１２０は酸化剤流路４により繋がり、酸化剤が酸化剤ガス供給ヘッダー１１９から加湿流路７により水回収部２を通って酸化剤移行流路９に入り、酸化剤移行流路９から酸化剤流路４により反応部１および水回収部２を通って酸化剤ガス排出ヘッダー１２０に流れるよう備えてあり、酸化剤ガス供給ヘッダー１１９から入った酸化剤は水回収部２で反対面を流れる酸化剤に含まれる蒸気により加湿され酸化剤移行流路９に流れ、酸化剤移行流路９より入った酸化剤が反応部１で発電反応を起こした後に水回収部２の反対面を流れる酸化剤により除湿され、再び反応部１で発電反応を起こした後に水回収部２の反対面を流れる酸化剤により除湿される。また、燃料ガス供給ヘッダー１１７と燃料ガス排出ヘッダー１１８は酸化剤セパレータ５の燃料流路６により繋がり、燃料が燃料ガス供給ヘッダー１１７から燃料流路６により反応部１を通り燃料ガス排出ヘッダー１１８に入るよう備えてある。
【００２７】
そして、単セルを図７に示すように、酸化剤ガス供給ヘッダー１１９により各単セルに供給された酸化剤は燃料セパレータ８上に設けられた加湿流路７に流入し、水回収部２で固体高分子電解質膜１０２を介して裏の面を流れる酸化剤中の水分により加湿された後に酸化剤移行流路９を通り、反対の面の酸化剤セパレータ５上の酸化剤流路４に流れる。酸化剤流路４を流れる酸化剤は反応部１に流入し発電反応が起きた後に水回収部２に流入し生成した蒸気が他方の面の酸化剤に移動することにより除湿され、再び反応部１に流入し発電反応が起きた後に水回収部２で同様に除湿され、酸化剤ガス排出ヘッダー１２０へ流入して燃料電池外部へと排出される。一方、燃料ガス供給ヘッダー１１７により供給された燃料は燃料セパレータ８上に設けられた燃料流路６により反応部１を流れ、他方の面を流れる酸化剤と発電反応が起き、燃料ガス排出ヘッダー１１８に流入し燃料電池外部へと排出される。
【００２８】
この様に、燃料電池に供給される酸化剤は外部から水分を供給することなく、発電反応を起こした酸化剤に含まれる生成した水分を水回収部２により供給される酸化剤へと移動させることで加湿し発電反応に必要な水分を固体高分子電解質膜１０２へ供給する。また、発電反応が進むにつれ発生した水分は酸化剤流路４を流れる酸化剤の湿度を上昇させて結露するが、反応部１と水回収部２を交互に通過することにより発電反応と除湿を繰り返すため結露を生じない。そのため、燃料に含まれる水分が酸化剤流路４上で結露による水滴または水滴のブリッジが流路を閉塞し酸化剤不足などの原因で起きる電圧低下を防止し、燃料電池を安定して運転することが可能となることに加え、流れが妨げられることによる圧力損失の増大を防止することが可能となる。また、加湿器および接続管内でガスの温度が低下することにより結露が生じていたが、セル内に水回収部２を設けることで反応部１が発電時に発生する熱により水回収部２は反応部１とほぼ同温度になるため、水回収部２での結露による圧力損失の増大を防止することができ、ガスを供給する供給機器の動力の低減と反応部１への高湿度のガスの最適な供給が可能となる。また、従来の方法では燃料電池の酸素の利用率を４０％、セルの温度を７０℃とする場合、発電反応により空気中の露点温度が運転温度を超えると結露が発生して運転に支障をきたすため、結露を起こさない供給空気の露点温度は約６０℃以下となる。しかし、空気温度が７０℃のときの露点温度の約６０℃は相対湿度では約６４％と低い。固体高分子電解質膜１０２を保湿するためには高湿度が望ましく、本実施例の燃料電池では反応途中で除湿する構成とすることよって、高湿度の空気を供給しながら反応途中で発生した水分を除湿することにより水分が結露することを防止した発電反応が可能となるため、発電効率が上がり製品寿命が長することが可能となる。
【００２９】
なお、本実施例においては反応後の酸化剤に含まれる水分を供給する酸化剤に回収する構造としたが、反応後の酸化剤に含まれる水分を供給する燃料に回収する構造でも良く、または、反応後の燃料に含まれる水分を供給する燃料または酸化剤に回収する構造でも良く、さらに、反応後の燃料と酸化剤の一方または両者に含まれる水分を供給する酸化剤と燃料に回収する構造でも良く、その作用効果に差異を生じない。また、本実施例では単セルを構成する部材は全て平面上に構成したが曲面を有する部材で構成しても良く、その作用効果に差異を生じない。
【００３０】
【発明の効果】
以上の実施例から明らかなように、本発明によればセル内に発電を行う反応部と発電反応により生成した水分で供給するガスを加湿する水回収部を設けることにより、加湿器を別途に設ける必要が無く、加湿のために燃料電池に外部から給水を不用とすると共に水の気化のために燃料電池の反応熱を用いることなくコージェネレーションシステムなどに有効利用できるという効果のある燃料電池を提供できる。
【００３１】
また、水回収部を反応部と同一セル内に設けることにより反応部が発電反応により生じる熱により水回収部が反応部とほぼ同一温度で保持されるため、水回収部における結露を防止でき圧力損失の増大による供給動力の増大や、ガスの流れが不安定になることを防止することができる効果のある燃料電池を提供できる。
【００３２】
また、反応部で生成した水分を水回収部で反応途中に除湿することにより反応部の初めから高湿度の燃料または酸化剤を供給することができ、酸化剤または燃料が流れる流路内で結露することなく一定の範囲で高い湿度が保持されるため、発電効率が上がり製品寿命が長く安定した発電反応ができる効果のある燃料電池を提供できる。
【図面の簡単な説明】
【図１】実施例１における電解質部の説明図
【図２】実施例１におけるセルの反応部の断面図
【図３】実施例１におけるセルの水回収部の断面図
【図４】実施例１における積層体の斜視図
【図５】実施例１における燃料セパレータの説明図
【図６】実施例１における酸化剤セパレータの説明図
【図７】実施例１における燃料および酸化剤の経路の模式図
【図８】従来例におけるセルの断面図
【図９】従来例における積層体の斜視図
【図１０】従来例における燃料ガスセパレータの説明図
【図１１】従来例における酸化剤ガスセパレータの説明図
【符号の説明】
１反応部
２水回収部
４酸化剤流路
６燃料流路
７加湿流路
９酸化剤移行流路
１０セル
１０１電解質部
１０２固体子分子電解質膜
１０３拡散層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell that generates power by an electrochemical reaction, and more particularly to a cell structure for adjusting the humidity of a gas that performs a power generation reaction.
[0002]
[Prior art]
Conventionally, as this type of fuel cell, one described in JP-A-6-132038 has been known. Hereinafter, a conventional fuel cell will be described mainly with reference to FIGS. 8, 9, 10 and 11. FIG. For ease of explanation, the case where the fuel is hydrogen and the oxidant is air will be described.
[0003]
As shown in FIG. 8, the electrolyte part 101 is configured by sandwiching a solid polymer electrolyte membrane 102 with a diffusion layer 103 that is conductive and coated with a catalyst, and a groove-like fuel gas channel is formed on one side of the electrolyte part 101. A conductive fuel gas separator 105 in which 104 is formed and a conductive oxidant gas separator 107 in which a groove-like oxidant gas channel 106 is formed on the other side are arranged. Is a groove having a depth of about 1 mm as shown in the sectional view. Further, the periphery of the diffusion layer 103 is surrounded by a sealing material 108.
[0004]
Next, as shown in FIG. 9, single cells 109a to 109j configured by sandwiching the electrolyte portion 101 between the fuel gas separator 105 and the oxidant gas separator 107 are stacked between the current collector plate a110 and the current collector plate B111. Then, this is sandwiched between the insulating plate a112 and the insulating plate B113, and both ends thereof are further sandwiched between the end plate a114 and the end plate B115 to form the laminate 116. As shown in FIG. 10, the oxidant gas supply header 119, the oxidant gas discharge header 120, the fuel so as to penetrate from the end plate A 114 to the current collector plate B 111 at the other end in the stack direction in the stacking direction of the stacked body 116. A gas supply header 117 and a fuel gas discharge header 118 are provided. As shown in FIG. 31, the fuel gas supply header 117 and the fuel gas discharge header 118 are communicated with each other through a groove of the fuel gas flow path 104 of the fuel gas separator 105. Further, the oxidant gas supply header 119 is provided in the same manner as the fuel gas supply header 117, and the oxidant gas discharge header 120 is provided in the same manner as the fuel gas discharge header 118. The oxidant gas supply header 119, the oxidant gas discharge header 120, As shown in FIG. 11, they communicate with each other through a groove in the oxidant gas flow path 106 of the oxidant gas separator 107.
[0005]
Next, the operation will be described. Hydrogen fed from the fuel gas supply header 117 into the stacked body 116 is discharged from the fuel gas discharge header 118 to the outside of the stacked body 116 through the fuel gas flow path 104 of the fuel gas separator 105 in the single cells 109a to 109j. . In addition, the air sent from the oxidant gas supply header 119 into the laminate 116 passes through the oxidant gas flow path 106 of the oxidant gas separator 107 of the single cells 109a to 109j, and passes from the oxidant gas discharge header 120 to the laminate. 116 is discharged outside.
[0006]
At this time, hydrogen flowing through the fuel gas flow path 104 of the electrolyte part 101 partially becomes ions and passes through the solid polymer electrolyte membrane 102 to reach the oxidant gas flow path 106 side. It reacts with oxygen in the flowing air to become water. In addition, a part of the water generated in the oxidant gas channel 106 penetrates the solid polymer electrolyte membrane 102 and moves to the fuel gas channel 104. At this time, a DC voltage is generated between the fuel gas separator 105 and the oxidant gas separator 107, and a DC voltage obtained by adding the DC voltage by the number of the stacked single cells 109a to 109j is between the current collector plate A110 and the current collector plate B111. Taken from.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-132038 (page 2, FIG. 2)
[Patent Document 2]
JP-A-6-68896 (page 3-4, Fig. 1-3)
[0008]
[Problems to be solved by the invention]
In such a conventional fuel cell, since the solid polymer electrolyte membrane cannot contain sufficient moisture, a method of supplying moisture into the fuel cell by humidifying the supplied fuel or oxidant is generally used. In addition, a separate humidifier such as bubbling or water spray is required, which has been a factor in increasing costs. In addition, when the fuel cell and the humidifier are installed separately, the fluid to be humidified causes pressure loss due to a complicated flow path that repeats diversion and merging in and between the humidifier and the main body of the fuel cell, There is a problem that the power of a gas supply device for supplying gas to the fuel cell becomes large, and a fuel cell capable of a simple configuration and a system configuration with low pressure loss is required.
[0009]
Further, when humidified gas is supplied to the fuel cell, moisture generated by the power generation reaction in the fuel cell main body condenses inside the fuel cell and closes the flow path. In addition, since the gas flowing in the fuel cell generates moisture due to the power generation reaction, the humidity differs between the upstream and downstream sides of the flow path, and the moisture distribution is uneven in the electrolyte section. There is a problem of becoming stable, and there is a demand for a fuel cell that prevents condensation due to moisture generated by a power generation reaction in the cell and maintains a uniform humidity.
[0010]
In addition, as in the fuel cell described in Japanese Patent Laid-Open No. 6-68896, the fuel gas separator and oxidant gas separator constituting the single cell and the electrolyte part are extended by a predetermined length at both ends, and the extended part is transmitted. As a membrane, a fuel gas humidification part is provided in one extension part, and an oxidant gas humidification part is provided in the other extension part. In each gas humidification part, the gas flow path formed in one gas separator and the other gas A method has been proposed in which the water supply passage configured in the separator is brought into contact with the electrolyte portion interposed therebetween, and humidification is performed by transferring moisture from the water supply passage to the gas flowing in the gas flow path on the other gas separator. However, in such a configuration, it is necessary to supply moisture from the outside in order to humidify the gas supplied to the fuel cell, and the reaction heat generated when the fuel cell generates power is reduced. When a fuel cell is used in a cogeneration system that collects water by rejected water and supplies it to equipment that uses external heat, the heat efficiency of the entire system is reduced by removing heat when water evaporates. There was a problem.
[0011]
The present invention solves such a conventional problem, and it is not necessary to provide a separate humidifier or the like when operating the fuel cell, reduces pressure loss due to shunting, etc., and depends on moisture generated by the power generation reaction. It is an object of the present invention to provide a fuel cell capable of maintaining stable operation and power generation efficiency of the fuel cell by preventing the blockage of the flow path and maintaining uniform humidity.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the fuel cell of the present invention includes a cell that generates power by an electrochemical reaction between a first reaction gas that is one of fuel and oxidant and a second reaction gas that is the other of fuel and oxidant. A solid polymer electrolyte fuel cell having a diffusion layer provided with a catalyst on both sides of a solid polymer electrolyte membrane, and a reaction part for performing a power generation reaction, disposed on the same surface as the reaction part, A water recovery unit that moves moisture through the membrane, a first reaction gas channel for flowing the first reaction gas through one surface of the reaction unit and the water recovery unit, and a second reaction gas on the other side of the reaction unit. A polymer electrolyte membrane includes a second reaction gas channel for flowing the reaction gas, a humidification channel for flowing the first reaction gas to the other surface of the water recovery unit, and the first reaction gas channel and the humidification channel. A first reactive gas transition flow path connected via a first reactive gas flowing through the humidified flow path Is flowed to the first reaction gas channel through the first reaction gas transfer channel after being humidified by the water recovery unit, and the first reaction gas flowing through the first reaction gas channel is water generated by the power generation reaction in the reaction unit. It is characterized in that it is dehumidified in the water recovery unit after it is generated .
[0013]
According to the present invention, a separate humidifier is not required, water supply to the fuel cell for humidification and reaction heat of the fuel cell are not required, so heat can be effectively used in a cogeneration system and the like. The water recovery unit is kept warm by the heat generated when the unit performs a power generation reaction, so that the humidification capacity can be improved and condensation can be prevented. Thus, a fuel cell capable of reducing the power loss of the gas supply device while suppressing the pressure loss due to is obtained.
[0014]
Another means is to use the same material by using an ion exchange membrane used in the reaction section for generating power of the fuel cell as a moisture permeable membrane in the water recovery section.
[0015]
According to the present invention, it is possible to obtain a fuel cell in which the configuration of the cell is simplified and the cost can be reduced in materials and production.
[0018]
Further, the other means is that the first reaction gas channel includes a path that alternately flows through the reaction unit and the water recovery unit, and the first reaction gas that flows through the first reaction gas channel is generated by a power generation reaction in the reaction unit. It is characterized in that generation of moisture and dehumidification in the water recovery unit are alternately repeated .
[0019]
According to the present invention, the moisture generated by the power generation reaction is dehumidified in the middle of the reaction, so that the fuel can be generated by the fuel or the oxidant without condensation while being highly humid throughout the reaction part. A battery is obtained.
[0020]
Another means is that the first reaction gas flowing through the first reaction gas channel is dehumidified by the water recovery unit after the generation of moisture by the power generation reaction in the reaction unit, flows into the reaction unit again, and generates power in the reaction unit. It is characterized in that it is dehumidified in the water recovery unit after the generation of water by the reaction .
[0021]
According to the present invention, it is possible to obtain a fuel cell in which moisture generated in the reaction part by the pair of reaction part and water recovery part can be dehumidified by the water recovery part each time and kept at a constant humidity.
In addition, the other means includes a conductive first separator in which a groove-shaped first reaction gas channel for flowing the first reaction gas is formed, and a groove-shaped humidification for flowing the first reaction gas. And a conductive second separator formed with a channel-shaped second reaction gas channel for circulating the second reaction gas, and the reaction unit and the water recovery unit are The first separator and the second separator are disposed between the first separator and the second separator, and the first separator and the second separator are for supplying a first reaction gas and for discharging the first reaction gas. The first reaction gas has a first reaction gas discharge hole, a second reaction gas supply hole for supplying the second reaction gas, and a second reaction gas discharge hole for discharging the second reaction gas. The supply hole and the first reaction gas transfer channel are connected by a humidification channel, and the first reaction gas transfer channel is connected. And the first reaction gas discharge hole is connected by a first reaction gas flow path, and the second reaction gas supply hole and the second reaction gas discharge hole are connected by a second reaction gas flow path. Is.

[0022]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a fuel cell including a cell that generates power by an electrochemical reaction between a fuel and an oxidant gas, and recovers the water generated by the power generation reaction in the cell to the gas supplied to the cell. It is possible to send the humidified gas to the reaction unit that generates power without the need for a humidifier for the gas to be sent to the cell, and the fuel cell does not require external water supply for humidification. It can be effectively used in a cogeneration system or the like without using the reaction heat of the fuel cell for water vaporization, and has the effect of preventing dew condensation in the water recovery part because it is formed in the cell. In addition, a water recovery unit is provided that recovers the moisture generated by the reaction in the middle of the power generation reaction in the cell into a gas that becomes a fuel and an oxidant, and the gas that has become excessively humidified by the moisture generated by the reaction. It can be dehumidified and has the effect of maintaining gas at a stable humidity. In addition, the reaction part that performs the power generation reaction and the water recovery part for recovering the water generated by the reaction to the supplied air are provided on the same surface, and the reaction part and the water recovery part are easily integrated. In addition, since the reaction part and the water recovery part are continuously provided, the gas can be divided once, and the thickness of the cell is not changed. In addition, the cathode flow path through which the oxidant flows or the anode flow path through which the fuel flows is generated by the reaction section by reciprocating the power generation reaction section and the water recovery section at least once. It has the effect that the flow path configuration of dehumidifying the water that has been removed by the water recovery unit can be easily formed. Further, the cathode flow path through which the oxidant flows or the anode flow path through which the fuel flows is provided with one or more bent portions so as to reciprocate between the power generation reaction section and the water recovery section. By bending the flow path, it is possible to easily reciprocate between the reaction part and the water recovery part to repeat the power generation reaction and dehumidification of the oxidant or fuel to keep the humidity constant. In addition, the cathode flow path through which the oxidant flows or the anode flow path through which the fuel flows first passes through the reaction section after passing through the power generation water recovery section, so that the oxidant or fuel before the power generation reaction can be always humidified. Have. In addition, the cathode flow path through which the oxidant flows or the anode flow path through which the fuel flows lastly passes through the water recovery unit, and since the humidity of the oxidant or fuel after the power generation reaction is highest, the supplied air is efficiently supplied. Has the effect of being humidified.
[0023]
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same number is attached | subjected to the same thing as a prior art example, and the detailed description is abbreviate | omitted. Further, in the embodiment, for easy understanding, a case where the fuel is a gas containing hydrogen and the oxidant is air will be described.
[0024]
【Example】
Example 1
As shown in FIG. 1 and FIG. 2, the electrolyte part 101 is provided with a reaction part 1 and a water recovery part 2 that are parts for generating power, and the periphery of the reaction part 1 and the water recovery part 2 is surrounded by a seal 3. is there. The water recovery unit 2 is provided with a solid polymer electrolyte membrane 102 as a moisture permeable membrane, has gas impermeability, and moves water. The reaction unit 1 has a solid polymer electrolyte membrane 102 provided with a diffusion layer 103 coated with a conductive catalyst on both sides. Then, a conductive oxidant separator 5 in which a groove-like oxidant flow path 4 is formed is disposed on one side of the electrolyte part 101, and a conductive structure in which a groove-shaped fuel flow path 6 and a humidification flow path 7 are formed on the other side. A fuel separator 8 is disposed. The oxidant channel 4, the fuel channel 6, and the humidification channel 7 are groove-shaped channels. Further, the electrolyte portion is provided with an oxidant transfer channel 9 that connects the humidification channel 7 and the oxidant channel 4.
[0025]
Next, as shown in FIG. 3, the single cells 10a to 10j constituted by sandwiching the electrolyte portion 101 between the oxidant separator 5 and the fuel separator 8 are stacked between the current collector plate A110 and the current collector plate B111. Is sandwiched between the insulating plate A112 and the insulating plate B113, and both ends thereof are further sandwiched between the end plate A114 and the end plate B115 to constitute the laminate 11. As shown in FIG. 4, in the stacking direction of the stacked body 11, an oxidant gas supply header 119, an oxidant gas discharge header 120, and a fuel are provided so as to penetrate from the end plate A114 to the current collector plate B111 at the other end in the stacking direction. A gas supply header 117 and a fuel gas discharge header 118 are provided.
[0026]
The flow path for the fuel and the oxidant is shown in FIGS. 5 and 6. The oxidant gas supply header 119 and the oxidant transfer path 9 are connected by the humidification path 7 of the fuel separator 8, and the oxidant transfer path 9 and the oxidant transfer path 9 are oxidized. The oxidant gas discharge header 120 is connected by the oxidant flow path 4, and the oxidant enters the oxidant transfer flow path 9 from the oxidant gas supply header 119 through the water recovery unit 2 through the humidification flow path 7, and the oxidant transfer flow path. 9 from the oxidant flow path 4 to the oxidant gas discharge header 120 through the reaction part 1 and the water recovery part 2, and the oxidant entered from the oxidant gas supply header 119 is opposite to the water recovery part 2 It is humidified by the steam contained in the oxidant flowing on the surface, flows to the oxidant transfer channel 9, and after the oxidant entering from the oxidant transfer channel 9 causes a power generation reaction in the reaction unit 1, the opposite side of the water recovery unit 2 Oxidizer flowing through Dividing wetted, it is dehumidified by an oxidizing agent flowing through the opposite side of the water collecting portion 2 after raised again the power generation reaction in the reaction unit 1. Further, the fuel gas supply header 117 and the fuel gas discharge header 118 are connected by the fuel flow path 6 of the oxidant separator 5, and the fuel passes from the fuel gas supply header 117 to the fuel gas discharge header 118 through the reaction section 1 through the fuel flow path 6. It is prepared to enter.
[0027]
Then, as shown in FIG. 7, the oxidant supplied to each single cell by the oxidant gas supply header 119 flows into the humidification channel 7 provided on the fuel separator 8, and the water recovery unit 2 After being humidified by the moisture in the oxidant flowing on the back surface through the solid polymer electrolyte membrane 102, it passes through the oxidant transfer channel 9 and flows to the oxidant channel 4 on the oxidant separator 5 on the opposite side. . The oxidant flowing through the oxidant flow path 4 flows into the reaction part 1 and after the power generation reaction takes place, the steam generated by flowing into the water recovery part 2 is dehumidified by moving to the oxidant on the other side, and again the reaction part. 1, after the power generation reaction occurs, the water recovery unit 2 similarly dehumidifies, flows into the oxidant gas discharge header 120, and is discharged outside the fuel cell. On the other hand, the fuel supplied by the fuel gas supply header 117 flows through the reaction section 1 through the fuel flow path 6 provided on the fuel separator 8, and a power generation reaction occurs with the oxidant flowing on the other surface, and the fuel gas discharge header 118. Is discharged to the outside of the fuel cell.
[0028]
In this way, the oxidant supplied to the fuel cell moves the generated water contained in the oxidant that has caused the power generation reaction to the oxidant supplied by the water recovery unit 2 without supplying water from the outside. Thus, the moisture required for the power generation reaction is supplied to the solid polymer electrolyte membrane 102 by humidification. In addition, the water generated as the power generation reaction proceeds increases the humidity of the oxidant flowing through the oxidant flow path 4 and condenses. By alternately passing through the reaction unit 1 and the water recovery unit 2, the power generation reaction and dehumidification are performed. Repeatedly does not cause condensation. Therefore, water drops due to condensation of moisture contained in the fuel on the oxidant channel 4 or bridges of water droplets block the channel and prevent voltage drop caused by oxidant shortage, and the fuel cell is stably operated. In addition to this, it is possible to prevent an increase in pressure loss due to the hindered flow. In addition, dew condensation occurred due to a decrease in the gas temperature in the humidifier and the connecting pipe, but by providing the water recovery unit 2 in the cell, the water recovery unit 2 reacts due to the heat generated by the reaction unit 1 during power generation. Since the temperature is almost the same as that of the unit 1, it is possible to prevent an increase in pressure loss due to condensation in the water recovery unit 2, and to reduce the power of the supply device that supplies the gas and the high humidity gas to the reaction unit 1. Optimal supply is possible. Further, in the conventional method, when the oxygen utilization rate of the fuel cell is 40% and the cell temperature is 70 ° C., if the dew point temperature in the air exceeds the operating temperature due to the power generation reaction, condensation occurs and the operation is hindered. Therefore, the dew point temperature of the supply air that does not cause condensation is about 60 ° C. or less. However, the dew point temperature of about 60 ° C. when the air temperature is 70 ° C. is as low as about 64% in relative humidity. In order to keep the solid polymer electrolyte membrane 102 moisturized, high humidity is desirable, and in the fuel cell of the present embodiment, by dehumidifying during the reaction, moisture generated during the reaction while supplying high-humidity air is removed. Dehumidification enables a power generation reaction that prevents moisture from condensing, thereby improving power generation efficiency and extending the product life.
[0029]
In the present embodiment, the structure is such that the moisture contained in the oxidant after the reaction is recovered to supply the oxidant, but the structure may be such that the moisture contained in the oxidant after the reaction is recovered in the fuel that is supplied, or Further, the structure may be such that the moisture contained in the fuel after the reaction is recovered to the fuel or the oxidant, and further the oxidant and the fuel that supply the moisture contained in one or both of the fuel and the oxidant after the reaction are recovered. It may be a structure and does not make a difference in its effects. Further, in this embodiment, all the members constituting the single cell are formed on a plane, but may be formed of a member having a curved surface, and there is no difference in the operation and effect.
[0030]
【The invention's effect】
As is clear from the above embodiments, according to the present invention, a humidifier is separately provided by providing a reaction unit for generating power and a water recovery unit for humidifying a gas supplied with moisture generated by the power generation reaction in the cell. There is no need to provide a fuel cell that can be effectively used in a cogeneration system or the like without using water supply from the outside for humidification and without using the reaction heat of the fuel cell for water vaporization. Can be provided.
[0031]
In addition, by providing the water recovery unit in the same cell as the reaction unit, the reaction unit is kept at almost the same temperature as the reaction unit by the heat generated by the power generation reaction. An effective fuel cell capable of preventing an increase in supply power due to an increase in loss and an unstable gas flow can be provided.
[0032]
In addition, by dehumidifying the water generated in the reaction unit during the reaction in the water recovery unit, high-humidity fuel or oxidant can be supplied from the beginning of the reaction unit, and dew condensation occurs in the flow path through which the oxidant or fuel flows. Therefore, since the high humidity is maintained within a certain range, it is possible to provide a fuel cell that has an effect of improving the power generation efficiency and having a long product life and a stable power generation reaction.
[Brief description of the drawings]
1 is an explanatory view of an electrolyte part in Example 1. FIG. 2 is a cross-sectional view of a reaction part of a cell in Example 1. FIG. 3 is a cross-sectional view of a water recovery part of a cell in Example 1. FIG. 5 is an explanatory diagram of a fuel separator in Example 1. FIG. 6 is an explanatory diagram of an oxidant separator in Example 1. FIG. 7 is a schematic diagram of fuel and oxidant paths in Example 1. FIG. 8 is a sectional view of a cell in a conventional example. FIG. 9 is a perspective view of a laminate in a conventional example. FIG. 10 is an explanatory diagram of a fuel gas separator in a conventional example. Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reaction part 2 Water recovery part 4 Oxidant flow path 6 Fuel flow path 7 Humidification flow path 9 Oxidant transfer flow path 10 Cell 101 Electrolyte part 102 Solid child molecular electrolyte membrane 103 Diffusion layer

Claims

In a polymer electrolyte fuel cell including a cell that generates power by an electrochemical reaction between a first reaction gas that is one of fuel and an oxidant and a second reaction gas that is the other of a fuel and an oxidant,
A reaction part having a diffusion layer provided with a catalyst on both sides of the solid polymer electrolyte membrane, and performing a power generation reaction;
A water recovery unit that is disposed on the same plane as the reaction unit and moves moisture through the solid polymer electrolyte membrane;
A first reaction gas flow path for flowing the first reaction gas through one surface of the reaction unit and the water recovery unit;
A second reaction gas flow path for flowing the second reaction gas to the other surface of the reaction section;
A humidifying channel for flowing the first reaction gas to the other surface of the water recovery unit;
A first reaction gas transition channel that connects the first reaction gas channel and the humidification channel via the polymer electrolyte membrane,
The first reaction gas flowing through the humidification channel flows through the first reaction gas transfer channel to the first reaction gas channel after being humidified by the water recovery unit, and passes through the first reaction gas channel. The polymer electrolyte fuel cell according to claim 1, wherein the flowing first reactive gas is dehumidified by the water recovery unit after moisture is generated by a power generation reaction in the reaction unit.

The first reaction gas channel includes a path that alternately flows through the reaction unit and the water recovery unit,
Wherein the first reaction gas flowing through the first reactant gas channel is according to claim 1, characterized in that alternating dehumidified in generation and the water recovery portion of the water by the power generation reaction in the reaction unit Solid polymer fuel cell.

The first reaction gas flowing through the first reaction gas channel is dehumidified by the water recovery unit after the generation of moisture by the power generation reaction in the reaction unit, flows into the reaction unit again, and generates power in the reaction unit. 3. The polymer electrolyte fuel cell according to claim 2 , wherein the water recovery unit dehumidifies the water after generation of water .

A conductive first separator formed with a groove-shaped first reaction gas channel for flowing the first reaction gas;
A grooved humidification channel for circulating the first reaction gas, and a channel for circulating the second reaction gas
A conductive second separator formed with a groove-shaped second reaction gas flow path;
And
The reaction part and the water recovery part are arranged between the first separator and the second separator,
The first separator and the second separator are:
A first reaction gas supply hole for supplying the first reaction gas;
A first reactive gas discharge hole for discharging the first reactive gas;
A second reaction gas supply hole for supplying the second reaction gas;
A second reaction gas discharge hole for discharging the second reaction gas,
The first reaction gas supply hole and the first reaction gas transfer channel are connected by the humidification channel,
The first reaction gas transfer channel and the first reaction gas discharge hole are connected by the first reaction gas channel,
2. The polymer electrolyte fuel cell according to claim 1 , wherein the second reactive gas supply hole and the second reactive gas discharge hole are connected by the second reactive gas flow path .