JP3591324B2

JP3591324B2 - Absorption refrigerator

Info

Publication number: JP3591324B2
Application number: JP25131898A
Authority: JP
Inventors: 孝寿瀧川; 公明田中
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 1998-09-04
Filing date: 1998-09-04
Publication date: 2004-11-17
Anticipated expiration: 2018-09-04
Also published as: JP2000081254A

Description

【０００１】
【発明の属する技術分野】
本発明は、臭化リチウムなどの吸収剤を含む吸収液に冷媒である水を吸収して冷凍サイクルを構成する吸収式冷凍機に関する。
【０００２】
【従来の技術】
従来から、吸収式冷凍機として、臭化リチウム（ＬｉＢｒ）などの物質を吸収剤として、その水溶液を吸収液として循環させる吸収式冷凍機が広く用いられている。吸収式冷凍機では、冷媒である水を蒸発器で蒸発させて冷却作用を行わせ、蒸発した水蒸気を吸収器で吸収液中に吸収させ、冷媒である水蒸気を吸収して濃度が薄められた吸収液を発生器で濃縮し、発生器で発生する水蒸気を凝縮器で凝縮させて蒸発器に送る吸収式冷凍サイクルを構成している。吸収式冷凍サイクルの効率を高めるために、発生器を高温発生器と低温発生器とに分ける二重効用型の吸収式冷凍機が多く使用されている。二重効用型の吸収式冷凍機の効率をさらに高めるために、特公昭５３−３５６６２および特公昭５３−３５６６３などでは、また単効用吸収式として特開昭４９−１０３２３９などでは、蒸発器と吸収器とを蒸発温度を変えて、二段に分ける先行技術が開示されている。
【０００３】
図１３は、二重効用型の吸収式冷凍機で、蒸発器（１）と吸収器（２）とを二段に分けている二段吸収サイクルの概略的な構成を示す。蒸発器（１）および吸収器（２）は、高圧側蒸発器（１ａ）および低圧側蒸発器（１ｂ）と高圧側吸収器（２ａ）および低圧側吸収器（２ｂ）とにそれぞれ分離されている。高温発生器（３）では高圧側吸収器（２ａ）から、冷媒である水蒸気を吸収して薄くなった吸収液が送られ、加熱して冷媒である水蒸気を発生させて吸収液を濃縮する。低温発生器（４）では、高温発生器（３）で濃縮された吸収液を、高温発生器（３）で得られる冷媒蒸気を用いて再度加熱し、さらに冷媒である水蒸気を発生させるとともに吸収液も濃縮させる。高温発生器（３）で発生した冷媒蒸気は低温発生器（４）内で冷却され凝縮し、凝縮冷媒は凝縮器（５）に入り、低温発生器（４）で発生した水蒸気は、凝縮器（５）内で冷却され、凝縮する。凝縮した冷媒である水は、高圧側蒸発器（１ａ）内に入り底部に溜まる。この冷媒は冷媒ポンプ（６）で低圧側蒸発器（１ｂ）の伝熱管上に散布され、蒸発させて伝熱管内の冷水の冷却を行う。蒸発しないで低圧側蒸発器（１ｂ）の底部へ溜まる冷媒は、低圧側蒸発器（１ｂ）と高圧側蒸発器（１ａ）とを継ぐ配管（１ｃ）を通って高圧側蒸発器（１ａ）内に散布される。
【０００４】
高圧側蒸発器（１ａ）および低圧側蒸発器（１ｂ）は、高圧側吸収器（２ａ）および低圧側吸収器（２ｂ）にそれぞれ連通している。低圧側吸収器（２ｂ）には、低温発生器（４）で濃縮された高い濃度の吸収液が投入され、冷媒である水蒸気の圧力が高圧側吸収器（２ａ）よりも低い圧力となるまで吸収することができる。このため、低圧側蒸発器（１ｂ）では、伝熱管内の冷水を高圧側蒸発器（１ａ）よりも低い温度まで冷却させることができる。二重効用型の吸収式冷凍サイクルでは、吸収液ポンプ（７）によって高圧側吸収器（２ａ）から高温発生器（３）に送込む希吸収液を、低温溶液熱交換器（８）で低温発生器（４）で濃縮した濃吸収液と熱交換して温度を高め、さらに高温溶液熱交換器（９）で高温発生器（３）で濃縮されて加熱された中間濃度の吸収液と熱交換して温度を高めてから、高温発生器（３）に投入している。これによって高温発生器（３）で吸収液を加熱するバーナ（１０）などの熱源から供給する熱エネルギを節約し、吸収式冷凍機としてのエネルギ効率を高め、成績係数ＣＯＰを高めている。
【０００５】
図１４は、図１３に示す二重効用型で二段吸収式の冷凍サイクルでの吸収液の状態変化を示す。高温発生器（３）の出側での吸収液の状態は▲１▼のように示される。この▲１▼の状態で、ＬｉＢｒ濃度がＸ２ｗｔ％である吸収液は、低温発生器（４）でさらにＬｉＢｒ濃度がＸ３ｗｔ％まで濃縮される。濃縮された吸収液は、▲２▼に示す状態から低温溶液熱交換器（８）に投入されて▲３▼に示す状態まで冷却され、低圧側吸収器（２ｂ）に入り、低圧側蒸発器（１ｂ）で蒸発する冷媒を吸収して、▲４▼に示す状態まで薄められる。次に吸収液は、高圧側吸収器（２ａ）に移されて、高圧側蒸発器（１ａ）で蒸発する冷媒である水蒸気を吸収し、ＬｉＢｒ濃度がＸ１ｗｔ％となるまで薄められて▲５▼に示す状態となる。高圧側吸収器（２ａ）からは、薄められた吸収液が吸収液ポンプ（７）で高温再生器（３）に送込まれる。途中で低温溶液熱交換器（８）および高温溶液熱交換器（９）を通る際に、濃吸収液と中間吸収液との間でそれぞれ熱交換し、温度が上昇した状態で高温発生器（３）に投入される。高温発生器（３）内では、バーナ（１０）で吸収液が加熱され、冷媒である水蒸気を蒸発させてＬｉＢｒ濃度がＸ１からＸ２まで増加するように濃縮が行われる。
【０００６】
【発明が解決しようとする課題】
図１３に示すような二段吸収サイクルを含む二重効用型の吸収式冷凍機では、特に二段目の高圧側吸収器（２ａ）で吸収液の濃度をＸ１ｗｔ％まで低くして、低圧側吸収器（２ｂ）に投入される濃度Ｘ３ｗｔ％との間の差である濃度幅を大きくして成績係数ＣＯＰを向上させることができる。しかしながら、吸収器（２）で冷却水を用いて冷却している吸収液を、高温発生器（３）ではバーナ（１０）などで加熱している。このような、加熱や冷却による顕熱変化の繰返しは、熱効率の低下を招く。高圧側吸収器（２ａ）から高温発生器（３）まで希吸収液を送る管路には、低温溶液熱交換器（８）および高温溶液熱交換器（９）を設けて、熱効率の改善を図っているけれども、さらに熱効率を改善して成績係数ＣＯＰを向上させることが要望されている。
【０００７】
本発明の目的は、二重効用型の吸収式冷凍サイクルで、熱効率を一層高めることができる吸収式冷凍機を提供することである。
【０００８】
【課題を解決するための手段】
本発明は、高温発生器（１３）、低温発生器（１４）、凝縮器（１５）、吸収器（１２）、蒸発器（１１）、高温溶液熱交換器（１９）および低温溶液熱交換器（１８）を含んで構成される二重効用型の吸収式冷凍機において、
吸収器（１２）および蒸発器（１１）は、冷媒の蒸発温度が異なる複数段に分割され、
吸収器（１２）から低温溶液熱交換器（１８）および高温溶液熱交換器（１９）を介して、高温発生器（１３）に希吸収液を輸送する希吸収液管路（２１）と、
希吸収液の一部を低温発生器（１４）に輸送する分岐管路（２３）と、
分岐管路（２３）で輸送される希吸収液と高温発生器（１３）で発生され低温発生器（１４）で凝縮されて凝縮器（１５）に輸送される冷媒とを熱交換させるドレン熱交換器（３３）と、
を備えることを特徴とする吸収式冷凍機である。
【０００９】
本発明に従えば、吸収器（１２）および蒸発器（１１）は、冷媒の蒸発温度が異なる複数段に分割されて、高温発生器（１３）、低温発生器（１４）、凝縮器（１５）、吸収器（１２）、蒸発器（１１）、高温溶液熱交換器（１９）および低温溶液熱交換器（１８）を含む二重効用型の吸収式冷凍機が構成される。吸収器（１２）で冷媒を吸収して濃度が薄められた希吸収液は、低温溶液熱交換器（１８）および高温溶液熱交換器（１９）を介して高温発生器（１３）に輸送する希吸収液管路（２１）から、一部が分岐管路（２３）を介して低温発生器（１４）に輸送される。希吸収液の一部が低温発生器（１４）に輸送されるので、高温発生器（１３）での加熱に要する熱エネルギを削減し、熱効率を高めることができる。
また、ドレン熱交換器（３３）を設けて、高温発生器（１３）で発生した冷媒が低温発生器（１４）で凝縮されて凝縮器（１５）に輸送される冷媒と、分岐管路（２３）から低温発生器（１４）に輸送される希溶液との間で熱交換を行うので、冷媒の有する熱を有効に利用し、かつ凝縮器（１５）に投入する冷媒を充分に冷却して、総合的な熱効率の改善を図ることができる。
【００１２】
また本発明は、前記分岐管路（２３）に、前記高温発生器（１３）で濃縮された吸収液を合流させて、前記低温発生器（１４）に輸送させることを特徴とする。
【００１３】
本発明に従えば、低温発生器（１４）には高温発生器（１３）からの中間濃度の吸収液と、分岐管路（２３）で分岐した吸収液とが合流して投入するので、高温発生器（１３）に戻す希吸収液の量を減らし、加熱に要するエネルギを節減することができる。
【００１６】
また本発明で前記分岐管路（２３）は、前記低温溶液熱交換器（１８）と高温溶液熱交換器（１９）との間の前記希吸収液管路（２１）から分岐することを特徴とする。
【００１７】
本発明に従えば、分岐管路（２３）で分岐する希吸収液は、低温溶液熱交換器（１８）で熱交換によって温度が上昇した状態で分岐するので、低温発生器（１４）での水蒸気発生に要する熱エネルギを節減することができる。
【００１８】
また本発明は、前記分岐管路（２３）への希吸収液の分配率が１５〜３０％であることを特徴とする。
【００１９】
本発明に従えば、分配率１５〜３０％で分岐管路（２３）へ希吸収液を分岐させるので、吸収サイクルの成績サイクルとして１．５以上の値を得ることができる。
【００２２】
【発明の実施の形態】
図１は、本発明の実施の第１形態としての吸収式冷凍サイクルの概略的な構成を示す。蒸発器（１１）、吸収器（１２）、高温発生器（１３）、低温発生器（１４）、凝縮器（１５）、冷媒ポンプ（１６）、吸収液ポンプ（１７）、低温溶液熱交換器（１８）および高温溶液熱交換器（１９）を含んで、二重効用型の吸収式冷凍サイクルが構成される。蒸発器（１１）は、高圧側蒸発器（１１ａ）と低圧側蒸発器（１１ｂ）とに、二段に分離されている。吸収器（１２）も、高圧側蒸発器（１１ａ）と連通する高圧側吸収器（１２ａ）と、低圧側蒸発器（１１ｂ）と連通する低圧側吸収器（１２ｂ）とに分離されている。
【００２３】
本実施形態では、高圧側蒸発器（１１ａ）と低圧側蒸発器（１１ｂ）との間で冷媒が冷媒ポンプ（１６）によって循環し、高圧側吸収器（１２ａ）および低圧側吸収器（１２ｂ）内の吸収液の吸収能力に応じた蒸気圧で冷媒の蒸発が行われる。高圧側吸収器（１２ａ）では、吸収液に冷媒がより多く吸収され、濃度が下がるので冷媒の蒸発圧力は高くなる。薄められた吸収液は、吸収液ポンプ（１７）で低温溶液熱交換器（１８）および高温溶液熱交換器（１９）を通る希吸収液管路（２１）で高温発生器（１３）に戻される。高温発生器（１３）で濃縮された濃吸収液は、濃吸収液管路（２２）から、高温溶液熱交換器（１９）および低温溶液熱交換器（１８）を介して、低圧側吸収器（１２ｂ）に送られる。
【００２４】
希吸収液管路（２１）で、低温溶液熱交換器（１８）と高温溶液熱交換器（１９）との間の部分からは、分岐管路（２３）が分岐し、希吸収液の一部を低温発生器（１４）に投入する。希吸収液は、いわばパラレルに高温発生器（１３）および低温発生器（１４）に投入される。低温発生器（１４）では、分岐管路（２３）を介して投入される希吸収液を、高温発生器（１３）で発生する冷媒蒸気で加熱し、冷媒蒸気を発生させて中間濃度まで濃縮した吸収液を、合流管路（２４）を介して、濃吸収液管路（２２）のうちの高温溶液熱交換器（１９）と低温溶液熱交換器（１８）との間の部分に合流させる。
【００２５】
二段に構成される吸収器（２）内を冷却するために設けられる冷却水管路（２５）は、高圧側吸収器（１２ａ）側に冷却水入口（２６）を有し、低圧側吸収器（１２ｂ）側に冷却水出口（２７）を有し、さらに凝縮器（１５）を冷却するために使用される。二段の蒸発器（１１）内で、冷媒である水の蒸発によって冷却される伝熱管である冷却水管路（２８）は、高圧側蒸発器（１１ａ）側に冷水入口（２９）を有し、低圧側蒸発器（１２ｂ）側に冷水出口（３０）を有する。
【００２６】
図２は、図１の実施形態で吸収液の状態変化を示す。高温発生器（１３）では、Ａ１で示すように、吸収液を温度が高く、濃度も高い状態まで濃縮する。濃縮された吸収液は、高温溶液熱交換器（１９）を通過する際に熱交換によって冷却され、低温発生器（１４）から合流管路（２４）を介して供給される中間濃度の吸収液と合流する際に、濃度がＸ３ｗｔ％まで減少する。合流した吸収液は、Ａ２で示す状態からＡ３で示す状態まで、低温溶液熱交換器（１８）で冷却され、低圧側吸収器（１２ｂ）内に散布される。低圧側吸収器（１２ｂ）内での冷媒の吸収によって、Ａ４で示すまで濃度が下がり、さらに高圧側吸収器（１２ａ）で、さらに濃度がＸ１ｗｔ％となるＡ５の状態まで冷媒を吸収する。
【００２７】
Ａ５の状態まで冷媒を吸収して薄められた希吸収液は、希吸収液管路（２１）を介して高温発生器（１３）に送込まれる。高温発生器（１３）では、バーナ（２０）による加熱で濃度がＸ１からＡ１に示すようにＸ３まで濃縮される。分岐管路（２３）へは、Ａ７で示すように希吸収液の一部が分岐され、分岐された希吸収液は低温溶液熱交換器（１８）を通過する際に熱交換によって温度が上昇しているので、低温発生器（１４）での加熱に必要な熱量を低減して、効率よく水蒸気を発生させることができる。また、希吸収液の一部が分岐されて、高温発生器（１３）でバーナ（２０）による高温までの加熱を行う希吸収液の量を減らすことができるので、熱エネルギを削減し、熱効率を向上させることができる。なお、分岐管（２３）で分岐させる希吸収液の割合は、５０％以下程度とする。
【００２８】
図３は、本発明の実施の第２形態としての概略的な配管構成を示す。本実施形態で、図１の実施形態に対応する部分には同一の参照符を付し、重複する説明は省略する。本実施形態では、分岐管路（２３）で希吸収液管路（２１）から分岐した希吸収液を、高温発生器（１３）で濃縮されて形成される中間濃度の吸収液と混合して低温発生器（１４）に投入している。中間濃度の吸収液は、中間吸収液管路（３１）から高温溶液熱交換器（１９）を介して合流する。すなわち、従来からの二重効用型の吸収式冷凍サイクルでは、全部の希吸収液を高温発生器（１３）に戻してバーナ（２０）などの熱源で加熱するところを、一部をバイパスして低温発生器（１４）に直接投入する構成となっている。
【００２９】
図４は、図３の実施形態での吸収液の状態変化を示す。高温発生器（１３）では、Ｂ１に示すような中間濃度の吸収液を低温発生器（１４）に投入する。低温発生器（１４）には、分岐管路（２３）を介して希吸収液も投入される。低温発生器（１４）では投入される吸収液を濃縮し、Ｂ２に示す状態の濃度Ｘ３ｗｔ％まで濃縮する。濃吸収液管路（２２）を介して、低温溶液熱交換器（１８）から低圧側吸収器（１２ｂ）に投入される濃吸収液は、Ｂ３からＢ４に示すように冷媒を吸収する。さらに高圧側吸収器（１２ａ）でＢ５に示すように冷媒を吸収して、溶液濃度がＸ１ｗｔ％まで希釈される。Ｂ５の状態の希吸収液は、吸収液ポンプ（１８）で希吸収液管路（２１）を介して、Ｂ６の状態で高温発生器（１３）に戻される。途中の分岐管路（２３）で、Ｂ７で示すように一部が分岐し直接低温発生器（１４）に投入される。分岐によって、高温発生器（１３）で加熱して、再び冷却する吸収液の量が減るので、バーナ（２０）の熱エネルギを節減し、吸収冷凍サイクルとしての熱効率を高めることができる。なお、分岐管路（２３）で分岐する希吸収液の割合は、全体の１０〜２０％程度とすることが好ましい。
【００３０】
図５は、本発明の第３形態としての吸収冷凍サイクルの概略的な構成を示す。本実施形態で、先行して説明した実施形態と対応する部分には同一の参照符を付し、重複する説明を省略する。本実施形態では、希吸収液管路（２１）で、低温溶液熱交換器（１８）の入側で分岐管路（２３）への分岐を行った後、高温発生器（１３）からの中間濃度の吸収液と合流させて低温発生器（１４）に投入している。分岐管路（２３）で分岐した希吸収液は、低温発生器（１４）で凝縮する冷媒を凝縮器（１５）に導くドレン管路（３２）の途中に設けられるドレン熱交換器（３３）で冷媒と熱交換し、冷媒の熱で昇温させて低温発生器（１４）に導く。冷媒は、熱交換によって冷却され凝縮器（１５）に導かれる。
【００３１】
図６は図５の実施形態での吸収液の状態変化を示す。Ｃ１，Ｃ２，Ｃ３，Ｃ４，Ｃ５，Ｃ６は、高温発生器（１３）の出側の状態、低温発生器（１４）の出側の状態、低圧側吸収器（１２ｂ）の入側の状態、低圧側吸収器（１２ｂ）の出側の状態、高圧側吸収器（１２ａ）の出側の状態および高温発生器（１３）の入側の状態をそれぞれ示す。分岐管路（２３）から分岐する希吸収液は、ドレン熱交換器（３３）での熱交換でＣ７に示す状態まで昇温され、高温発生器（１３）からの中間濃度の吸収液の濃度を少し薄めた状態Ｃ８から低温発生器（１４）に投入されて、Ｃ２に示す状態まで濃縮される。本実施形態では冷却水入口（２６）と冷却水出口（２７）とでの冷却水の温度差を５℃としたときに、成績係数ＣＯＰとして１．５０４程度の値が得られている。冷却水の温度差を、さらに大きくして８℃にすると、７に示すような状態変化が得られ、吸収サイクルの成績係数ＣＯＰとして１．５３５の値が得られている。図７に示す各状態Ｄ１，Ｄ２，Ｄ３，Ｄ４，Ｄ５，Ｄ６，Ｄ７，Ｄ８は、図６のＣ１，Ｃ２，Ｃ３，Ｃ４，Ｃ５，Ｃ６，Ｃ７，Ｃ８にそれぞれ対応している。吸収サイクルの成績係数ＣＯＰは、分岐管路（２３）で分岐する希溶液の全体に対する割合によって図８に示すように変化する。図８では分岐管路（２３）に、全体の２５％の希吸収液を分岐させるときに成績係数ＣＯＰがピーク値を取ることが判る。成績係数ＣＯＰの値としては、一般的に通常の二重効用型の吸収式冷凍サイクルでは１．０であることが知られているので、本実施形態で得られる１．５以上の値は格段に優れている。図８からは少なくとも１５％〜３０％の範囲で、成績係数ＣＯＰが１．５３を超えていることが判る。
【００３２】
図９は、本発明の実施の第４形態としての吸収冷凍サイクルの概略的な構成を示す。本実施形態で、先行して説明した実施形態と対応する部分には同一の参照符を付し、重複する説明を省略する。本実施形態では、図５の実施形態とは異なり、分岐管路（２３）を、図１の実施形態と同様に、希吸収液管路（２１）の低温溶液熱交換器（１８）と高温溶液熱交換器（１９）との間の部分から分岐させ、その後でドレン熱交換器（３３）での熱交換を行っている。本実施形態での吸収液の状態変化を図１０に示すように、図４に示す状態変化と類似している。すなわち、各状態Ｅ１〜Ｅ７は、図４の状態Ｂ１〜Ｂ７にそれぞれ対応していると考えられる。
【００３３】
図１１は、本発明の実施の第５形態としての概略的な吸収冷凍サイクルの構成を示す。本実施形態で、先行して説明した各実施形態に対応する部分には同一の参照符を付し、重複する説明を省略する。本実施形態では高圧側吸収器（１２ａ）から吸収液ポンプ（１７）で希吸収液管路（２１）に送込まれる希吸収液を、溶液熱交換器（１８）から低温発生器（１４）に導いた後、中間濃度まで濃縮した吸収液を吸収液ポンプ（３４）で、中間吸収液管路（３１）から高温溶液熱交換器（１９）を介して高温発生器（１３）に投入している。高温発生器（１３）で濃縮された高濃度の吸収液は、濃吸収液管路（２２）を介して、高温溶液熱交換器（１９）および低温溶液熱交換器（１８）から低圧側吸収器（１２ｂ）に投入している。本実施形態では、希吸収液が戻る際に、順次濃縮され、図１３に示す濃縮順序とは逆になっている。
【００３４】
図１２は、図１１の実施形態の動作での吸収液の状態変化を示す。Ｆ１は高温発生器（１３）の出側の状態を示す。Ｆ２は、濃吸収液管路（２２）で、高温溶液熱交換器（１９）と低温溶液熱交換器（１８）との中間部分での吸収液の状態を示す。Ｆ３は、低圧側吸収器（１２ｂ）の入側での吸収液の状態を示す。Ｆ１からＦ３まで、溶液濃度は変わらずに、温度が高温溶液熱交換器（１９）および低温溶液熱交換器（１８）での熱交換で低下している。低圧側吸収器（１２ｂ）では、吸収液に冷媒である水蒸気が吸収され、濃度が低下してＦ４に示す状態に変化する。さらに高圧側吸収器（１２ａ）で冷媒を吸収し、濃度が低下してＦ５に示す状態で吸収液ポンプ（１７）で低温発生器（１４）に投入される。低温発生器（１４）では、Ｆ７で示す状態から吸収液の濃度を濃縮し、さらに吸収液ポンプ（３４）で高温発生器（１４）の入口側に投入する状態Ｆ６の濃度まで濃縮する。本実施形態では、吸収液を最終的に高温発生器（１３）で濃縮するので、高温で高濃度まで濃縮させることができる。低圧側吸収器（１２ｂ）の温度をあまり下げないでも、高濃度の吸収液で低い蒸気圧を得ることができ、複数段の吸収高濃度側から低濃度側へ広い濃度幅を得て、成績係数を向上させることができる。
【００３５】
以上説明した各実施形態では、蒸発器（１１）および吸収器（１２）をそれぞれ２段ずつに分けて形成しているけれども、さらに段数が多い多段式にすることもでき、吸収器（１２）全体への入側の吸収液の濃度と出側の吸収液の濃度との差である濃度幅を大きくして、吸収冷凍サイクルの動作の効率を高めることができる。
【００３６】
【発明の効果】
以上のように本発明によれば、吸収器（１２）から高温再生器（１３）に送る希吸収液の一部を分岐して低温発生器（１４）に送るので、吸収液の顕熱変化を減少させて高温発生器（１３）で必要となる加熱エネルギを節減し、二重効用型の吸収サイクルのエネルギ効率を改善して、成績係数ＣＯＰを向上させることができる。
また、低温発生器（１４）から凝縮器（１５）に送られる冷媒の有する熱を、ドレン熱交換器（３３）で分岐管路（２３）で分岐する希吸収液と熱交換させるので、冷媒の有する熱エネルギを有効に利用して吸収冷凍サイクルとしての熱効率を一層向上させることができる。
【００３８】
また本発明によれば、高温発生器（１３）で濃縮した中間濃度の吸収液に分岐管路（２３）から分岐する希吸収液に合流させて低温発生器（１４）に投入するので、高温発生器（１３）で加熱する必要がある希吸収液の量を減らし、熱効率を改善することができる。
【００４０】
また本発明によれば、分岐管路（２３）で分岐する希吸収液は、低温溶液熱交換器（１８）の熱交換で温度が上昇するので、低温再生器（１４）で加熱に要するエネルギを削減し、吸収冷凍サイクルとしての熱効率を高めることができる。
【００４１】
また本発明によれば、分岐させる希吸収液の分配率を１５〜３０％として、吸収サイクルの成績係数が１．５３を超えるようにすることができる。
【図面の簡単な説明】
【図１】本発明の実施の第１形態の吸収冷凍サイクルの概略的な構成を示す配管系統図である。
【図２】図１の実施形態での吸収液の状態変化を示すサイクル線図である。
【図３】本発明の実施の第２形態の吸収冷凍サイクルの概略的な構成を示す配管系統図である。
【図４】図３の実施形態の吸収液の状態変化を示すサイクル線図である。
【図５】本発明の実施の第３形態の吸収冷凍サイクルの概略的な構成を示す配管系統図である。
【図６】図５の実施形態での吸収液の状態変化を示すサイクル線図である。
【図７】図５の実施形態で、冷却水の温度差を大きくしたときの吸収液の状態変化を示すサイクル線図である。
【図８】図５の実施形態で、分岐管路（２３）側に分岐する希吸収液の割合と成績係数ＣＯＰとの関係を示すグラフである。
【図９】本発明の実施の第４形態の吸収式冷凍サイクルの概略的な構成を示す配管系統図である。
【図１０】図９の実施形態での吸収液の状態変化を示すサイクル線図である。
【図１１】本発明の実施の第５形態の吸収式冷凍サイクルの概略的な構成を示す配管系統図である。
【図１２】図１１の実施形態での吸収液の状態変化を示すサイクル線図である。
【図１３】従来からの二段吸収式の二重効用型吸収式冷凍サイクルの概略的な構成を示す配管系統図である。
【図１４】図１３の吸収式冷凍サイクルでの吸収液の状態変化を示すサイクル線図である。
【符号の説明】
１１蒸発器
１１ａ高圧側蒸発器
１１ｂ低圧側蒸発器
１２吸収器
１２ａ高圧側蒸発器
１２ｂ低圧側蒸発器
１３高温発生器
１４低温発生器
１５凝縮器
１７吸収液ポンプ
１８低温溶液熱交換器
１９高温溶液熱交換器
２１希吸収液管路
２２濃吸収液管路
２３分岐管路
２４合流管路
２９冷水入口
３０冷水出口
３１中間吸収液管路
３２ドレン管路
３３ドレン熱交換器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an absorption refrigerating machine that forms a refrigerating cycle by absorbing water as a refrigerant into an absorbing liquid containing an absorbent such as lithium bromide.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an absorption refrigerator, an absorption refrigerator in which a substance such as lithium bromide (LiBr) is used as an absorbent and an aqueous solution thereof is circulated as an absorbent is widely used. In the absorption refrigerator, water as a refrigerant was evaporated by an evaporator to perform a cooling action, and the evaporated water vapor was absorbed into an absorbent by an absorber, and the concentration of the refrigerant was reduced by absorbing the water vapor as a refrigerant. An absorption refrigeration cycle is configured in which the absorption liquid is concentrated by a generator, and the steam generated by the generator is condensed by a condenser and sent to an evaporator. In order to increase the efficiency of the absorption refrigeration cycle, a double effect absorption chiller that divides a generator into a high-temperature generator and a low-temperature generator is often used. In order to further increase the efficiency of the double-effect absorption refrigerator, the evaporator and absorption are disclosed in Japanese Patent Publication Nos. 53-35662 and 53-35663 and in Japanese Patent Application Laid-Open No. 49-103239 as a single-effect absorption type. A prior art has been disclosed in which a vessel is divided into two stages by changing the evaporation temperature.
[0003]
FIG. 13 shows a schematic configuration of a two-stage absorption cycle in which an evaporator (1) and an absorber (2) are divided into two stages in a double-effect absorption refrigerator. The evaporator (1) and the absorber (2) are separated into a high-pressure side evaporator (1a) and a low-pressure side evaporator (1b), and a high-pressure side absorber (2a) and a low-pressure side absorber (2b), respectively. I have. In the high-temperature generator (3), the absorbing liquid which has absorbed the water vapor as the refrigerant and has become thinner is sent from the high-pressure side absorber (2a) and is heated to generate the water vapor as the refrigerant and concentrate the absorbing liquid. In the low-temperature generator (4), the absorbent concentrated in the high-temperature generator (3) is heated again by using the refrigerant vapor obtained in the high-temperature generator (3) to generate and absorb water vapor as a refrigerant. The liquid is also concentrated. The refrigerant vapor generated in the high-temperature generator (3) is cooled and condensed in the low-temperature generator (4), the condensed refrigerant enters the condenser (5), and the steam generated in the low-temperature generator (4) is condensed. It cools and condenses in (5). Water, which is the condensed refrigerant, enters the high-pressure side evaporator (1a) and accumulates at the bottom. This refrigerant is sprayed on the heat transfer tube of the low-pressure side evaporator (1b) by the refrigerant pump (6) and evaporated to cool the cold water in the heat transfer tube. The refrigerant remaining at the bottom of the low-pressure side evaporator (1b) without evaporating passes through a pipe (1c) connecting the low-pressure side evaporator (1b) and the high-pressure side evaporator (1a) and is in the high-pressure side evaporator (1a). Sprayed on.
[0004]
The high-pressure side evaporator (1a) and the low-pressure side evaporator (1b) communicate with the high-pressure side absorber (2a) and the low-pressure side absorber (2b), respectively. The high-pressure absorbent concentrated in the low-temperature generator (4) is supplied to the low-pressure side absorber (2b) until the pressure of the water vapor as the refrigerant becomes lower than that of the high-pressure side absorber (2a). Can be absorbed. Therefore, in the low-pressure side evaporator (1b), the cold water in the heat transfer tube can be cooled to a temperature lower than that of the high-pressure side evaporator (1a). In the double-effect absorption refrigeration cycle, the diluted absorption liquid sent from the high-pressure side absorber (2a) to the high-temperature generator (3) by the absorption liquid pump (7) is cooled by the low-temperature solution heat exchanger (8). The heat is exchanged with the concentrated absorption liquid concentrated in the generator (4) to increase the temperature, and further the heat is exchanged with the intermediate concentration absorption liquid heated and concentrated in the high temperature generator (3) in the high temperature solution heat exchanger (9). After the temperature has been increased by replacement, it is put into the high temperature generator (3). As a result, heat energy supplied from a heat source such as a burner (10) for heating the absorbing liquid in the high-temperature generator (3) is saved, the energy efficiency of the absorption refrigerator is increased, and the coefficient of performance COP is increased.
[0005]
FIG. 14 shows a state change of the absorbent in the double effect type two-stage absorption refrigeration cycle shown in FIG. The state of the absorbent at the outlet of the high temperature generator (3) is shown as (1). In the state (1), the absorbent having the LiBr concentration of X2 wt% is further concentrated by the low temperature generator (4) to the LiBr concentration of X3 wt%. The concentrated absorbent is introduced into the low-temperature solution heat exchanger (8) from the state shown in (2), cooled to the state shown in (3), enters the low-pressure side absorber (2b), and enters the low-pressure side evaporator. The refrigerant evaporating in (1b) is absorbed and is diluted to the state shown in (4). Next, the absorbing liquid is transferred to the high-pressure side absorber (2a), absorbs water vapor as a refrigerant evaporated in the high-pressure side evaporator (1a), and is diluted until the LiBr concentration becomes X1 wt% (5). The state shown in FIG. From the high pressure side absorber (2a), the diluted absorbent is sent to the high temperature regenerator (3) by the absorbent pump (7). When passing through the low-temperature solution heat exchanger (8) and the high-temperature solution heat exchanger (9) on the way, heat is exchanged between the concentrated absorbing solution and the intermediate absorbing solution, respectively. Entered in 3). In the high-temperature generator (3), the absorbing liquid is heated by the burner (10), and vaporization as a refrigerant is performed to concentrate the LiBr so that the LiBr concentration increases from X1 to X2.
[0006]
[Problems to be solved by the invention]
In a double effect absorption refrigerator including a two-stage absorption cycle as shown in FIG. 13, the concentration of the absorbent is reduced to X1 wt% in the second-stage high-pressure side absorber (2a), and the low-pressure side The coefficient of performance COP can be improved by increasing the concentration width, which is the difference between the concentration X3 wt% supplied to the absorber (2b). However, in the high-temperature generator (3), the absorbing liquid cooled by the cooling water in the absorber (2) is heated by a burner (10) or the like. Such repetition of the sensible heat change due to heating or cooling causes a decrease in thermal efficiency. A low-temperature solution heat exchanger (8) and a high-temperature solution heat exchanger (9) are provided in the pipeline for sending the dilute absorption liquid from the high-pressure side absorber (2a) to the high-temperature generator (3) to improve thermal efficiency. However, it is desired to further improve the thermal efficiency to improve the coefficient of performance COP.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an absorption refrigerator having a double effect absorption refrigeration cycle and capable of further improving thermal efficiency.
[0008]
[Means for Solving the Problems]
The present invention relates to a high temperature generator (13), a low temperature generator (14), a condenser (15), an absorber (12), an evaporator (11), a high temperature solution heat exchanger (19) and a low temperature solution heat exchanger. In a double effect absorption refrigerator including (18),
The absorber (12) and the evaporator (11) are divided into a plurality of stages having different evaporation temperatures of the refrigerant,
A dilute absorbent line (21) for transporting dilute absorbent from the absorber (12) to the high temperature generator (13) via the low temperature solution heat exchanger (18) and the high temperature solution heat exchanger (19);
A branch line (23) for transporting a part of the diluted absorption liquid to the low temperature generator (14);
Drain heat for exchanging heat between the dilute absorption liquid transported in the branch line (23) and the refrigerant generated in the high temperature generator (13) and condensed in the low temperature generator (14) and transported to the condenser (15) An exchanger (33);
It is an absorption refrigerator characterized by having.
[0009]
According to the present invention, the absorber (12) and the evaporator (11) are divided into a plurality of stages having different refrigerant evaporation temperatures, and the high temperature generator (13), the low temperature generator (14), and the condenser (15) are provided. ), An absorber (12), an evaporator (11), a high-temperature solution heat exchanger (19) and a low-temperature solution heat exchanger (18). The diluted absorption liquid whose concentration has been reduced by absorbing the refrigerant in the absorber (12) is transported to the high temperature generator (13) through the low temperature solution heat exchanger (18) and the high temperature solution heat exchanger (19). From the dilute absorbing liquid line (21), a part is transported to the low temperature generator (14) through the branch line (23). Since a part of the diluted absorption liquid is transported to the low-temperature generator (14), the heat energy required for heating in the high-temperature generator (13) can be reduced, and the thermal efficiency can be increased.
In addition, a drain heat exchanger (33) is provided so that the refrigerant generated in the high-temperature generator (13) is condensed in the low-temperature generator (14) and transported to the condenser (15). Since heat exchange is performed between the dilute solution transported from 23) to the low-temperature generator (14), the heat of the refrigerant is effectively used, and the refrigerant introduced into the condenser (15) is sufficiently cooled. Thus, the overall thermal efficiency can be improved.
[0012]
Further, the present invention is characterized in that the absorption liquid concentrated in the high-temperature generator (13) is combined with the branch pipe (23) and transported to the low-temperature generator (14).
[0013]
According to the present invention, the intermediate concentration absorbent from the high temperature generator (13) and the absorbent branched in the branch line (23) are merged and supplied to the low temperature generator (14). The amount of the diluted absorbing liquid returned to the generator (13) can be reduced, and the energy required for heating can be reduced.
[0016]
In the present invention, the branch line (23) branches from the diluted absorption liquid line (21) between the low-temperature solution heat exchanger (18) and the high-temperature solution heat exchanger (19). And
[0017]
According to the present invention, the dilute absorbent branched in the branch line (23) branches in a state where the temperature is increased by heat exchange in the low-temperature solution heat exchanger (18). The heat energy required for steam generation can be reduced.
[0018]
Further, the present invention is characterized in that the distribution rate of the diluted absorbing liquid to the branch pipe (23) is 15 to 30%.
[0019]
According to the present invention, the dilute absorbent is branched into the branch pipe (23) at a distribution ratio of 15 to 30%, so that a value of 1.5 or more can be obtained as a performance cycle of the absorption cycle.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a schematic configuration of an absorption refrigeration cycle as a first embodiment of the present invention. Evaporator (11), absorber (12), high temperature generator (13), low temperature generator (14), condenser (15), refrigerant pump (16), absorption liquid pump (17), low temperature solution heat exchanger (18) and the high-temperature solution heat exchanger (19) comprise a double effect absorption refrigeration cycle. The evaporator (11) is divided into two stages, a high-pressure side evaporator (11a) and a low-pressure side evaporator (11b). The absorber (12) is also separated into a high-pressure side absorber (12a) communicating with the high-pressure side evaporator (11a) and a low-pressure side absorber (12b) communicating with the low-pressure side evaporator (11b).
[0023]
In this embodiment, the refrigerant is circulated between the high-pressure side evaporator (11a) and the low-pressure side evaporator (11b) by the refrigerant pump (16), and the high-pressure side absorber (12a) and the low-pressure side absorber (12b). Evaporation of the refrigerant is performed at a vapor pressure according to the absorption capacity of the absorbing liquid in the inside. In the high-pressure side absorber (12a), the refrigerant is more absorbed by the absorbing liquid and the concentration is reduced, so that the evaporating pressure of the refrigerant is increased. The diluted absorbent is returned to the high-temperature generator (13) by the absorbent pump (17) and the dilute absorbent line (21) passing through the low-temperature solution heat exchanger (18) and the high-temperature solution heat exchanger (19). It is. The concentrated absorbent concentrated in the high-temperature generator (13) is supplied from the concentrated absorbent line (22) through the high-temperature solution heat exchanger (19) and the low-temperature solution heat exchanger (18) to the low-pressure side absorber. (12b).
[0024]
A branch pipe (23) branches off from the portion between the low-temperature solution heat exchanger (18) and the high-temperature solution heat exchanger (19) in the dilute absorption liquid pipe (21), so that one of the dilute absorption liquid is removed. The part is put into the low temperature generator (14). The diluted absorption liquid is supplied to the high-temperature generator (13) and the low-temperature generator (14) in a parallel manner. In the low-temperature generator (14), the diluted absorption liquid supplied through the branch pipe (23) is heated by the refrigerant vapor generated in the high-temperature generator (13), and the refrigerant vapor is generated to be concentrated to an intermediate concentration. The absorbed liquid is merged via a merging line (24) into a portion of the concentrated absorbing liquid line (22) between the high-temperature solution heat exchanger (19) and the low-temperature solution heat exchanger (18). Let it.
[0025]
A cooling water pipe (25) provided for cooling the inside of the absorber (2) composed of two stages has a cooling water inlet (26) on the high pressure side absorber (12a) side, and has a low pressure side absorber. It has a cooling water outlet (27) on the (12b) side and is used for cooling the condenser (15). In the two-stage evaporator (11), a cooling water pipe (28) as a heat transfer tube cooled by evaporation of water as a refrigerant has a cold water inlet (29) on the high-pressure side evaporator (11a) side. And a cold water outlet (30) on the low pressure side evaporator (12b) side.
[0026]
FIG. 2 shows a state change of the absorbing liquid in the embodiment of FIG. In the high temperature generator (13), the absorption liquid is concentrated to a state where the temperature is high and the concentration is high, as indicated by A1. The concentrated absorbent is cooled by heat exchange when passing through the high-temperature solution heat exchanger (19), and is supplied from the low-temperature generator (14) through the merging line (24) to an intermediate concentration absorbent. At the same time, the concentration decreases to X3 wt%. The combined absorbent is cooled by the low-temperature solution heat exchanger (18) from the state indicated by A2 to the state indicated by A3, and is sprayed into the low-pressure side absorber (12b). Due to the absorption of the refrigerant in the low-pressure side absorber (12b), the concentration decreases until indicated by A4, and the high-pressure side absorber (12a) further absorbs the refrigerant to the state of A5 where the concentration further becomes X1 wt%.
[0027]
The diluted absorbing liquid diluted by absorbing the refrigerant to the state of A5 is sent to the high temperature generator (13) through the diluted absorbing liquid line (21). In the high temperature generator (13), the concentration is increased from X1 to X3 as shown by A1 by heating by the burner (20). A part of the diluted absorption liquid is branched into the branch pipe line (23) as indicated by A7, and the temperature of the branched diluted absorption liquid increases due to heat exchange when passing through the low-temperature solution heat exchanger (18). Therefore, the amount of heat required for heating in the low-temperature generator (14) can be reduced, and steam can be generated efficiently. In addition, since a part of the rare absorbing liquid is branched and the amount of the rare absorbing liquid to be heated to a high temperature by the burner (20) in the high-temperature generator (13) can be reduced, heat energy can be reduced and thermal efficiency can be reduced. Can be improved. The ratio of the diluted absorbing liquid branched in the branch pipe (23) is set to about 50% or less.
[0028]
FIG. 3 shows a schematic piping configuration as a second embodiment of the present invention. In the present embodiment, portions corresponding to the embodiment of FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. In the present embodiment, the dilute absorbing liquid branched from the dilute absorbing liquid pipe (21) in the branch pipe (23) is mixed with an intermediate concentration absorbing liquid formed by being concentrated in the high temperature generator (13). It has been charged to the low temperature generator (14). The intermediate concentration absorbent merges from the intermediate absorbent line (31) via the high temperature solution heat exchanger (19). That is, in the conventional double-effect absorption refrigeration cycle, all of the diluted absorption liquid is returned to the high-temperature generator (13) and heated by a heat source such as a burner (20). It is configured to be directly supplied to the low-temperature generator (14).
[0029]
FIG. 4 shows a state change of the absorbing liquid in the embodiment of FIG. In the high temperature generator (13), an absorbent having an intermediate concentration as indicated by B1 is introduced into the low temperature generator (14). The low temperature generator (14) is also charged with a dilute absorption liquid via a branch line (23). In the low-temperature generator (14), the absorption liquid to be supplied is concentrated to a concentration X3wt% in the state shown in B2. The concentrated absorbent introduced into the low-pressure side absorber (12b) from the low-temperature solution heat exchanger (18) via the concentrated absorbent line (22) absorbs the refrigerant as indicated by B3 to B4. Further, the refrigerant is absorbed by the high pressure side absorber (12a) as indicated by B5, and the solution concentration is diluted to X1 wt%. The diluted absorbing liquid in the state of B5 is returned to the high temperature generator (13) in the state of B6 through the diluted absorbing liquid line (21) by the absorbing liquid pump (18). In the branch pipe (23) on the way, a part is branched as shown by B7 and directly fed into the low temperature generator (14). By branching, the amount of the absorbing liquid heated and cooled again by the high-temperature generator (13) is reduced, so that the heat energy of the burner (20) can be reduced, and the thermal efficiency of the absorption refrigeration cycle can be increased. In addition, it is preferable that the ratio of the diluted absorbing liquid branched in the branch pipe (23) is about 10 to 20% of the whole.
[0030]
FIG. 5 shows a schematic configuration of an absorption refrigeration cycle as a third embodiment of the present invention. In the present embodiment, portions corresponding to those of the previously described embodiment are denoted by the same reference numerals, and redundant description will be omitted. In the present embodiment, after branching to the branch line (23) at the inlet side of the low-temperature solution heat exchanger (18) in the diluted absorption liquid line (21), the intermediate from the high-temperature generator (13) is formed. It is combined with the absorption liquid of the concentration and introduced into the low-temperature generator (14). The dilute absorption liquid branched in the branch line (23) is provided in a drain heat exchanger (33) provided in the middle of a drain line (32) for guiding the refrigerant condensed in the low-temperature generator (14) to the condenser (15). Exchanges heat with the refrigerant, and the temperature of the refrigerant is increased by the heat of the refrigerant to be guided to the low-temperature generator (14). The refrigerant is cooled by heat exchange and guided to the condenser (15).
[0031]
FIG. 6 shows a state change of the absorbing liquid in the embodiment of FIG. C1, C2, C3, C4, C5, and C6 indicate the state of the outlet of the high-temperature generator (13), the state of the outlet of the low-temperature generator (14), the state of the inlet of the low-pressure absorber (12b), The state of the outlet side of the low-pressure side absorber (12b), the state of the outlet side of the high-pressure side absorber (12a), and the state of the inlet side of the high-temperature generator (13) are shown, respectively. The temperature of the diluted absorbing liquid branched from the branch pipe (23) is raised to a state indicated by C7 by heat exchange in the drain heat exchanger (33), and the concentration of the intermediate-concentrated absorbing liquid from the high-temperature generator (13). Is fed into the low-temperature generator (14) from a slightly diluted state C8, and concentrated to a state indicated by C2. In this embodiment, when the temperature difference between the cooling water at the cooling water inlet (26) and the cooling water outlet (27) is 5 ° C., a value of about 1.504 is obtained as the coefficient of performance COP. When the temperature difference of the cooling water is further increased to 8 ° C., a state change as shown in 7 is obtained, and a value of 1.535 is obtained as the coefficient of performance COP of the absorption cycle. The states D1, D2, D3, D4, D5, D6, D7, and D8 shown in FIG. 7 correspond to C1, C2, C3, C4, C5, C6, C7, and C8 in FIG. 6, respectively. The coefficient of performance COP of the absorption cycle changes as shown in FIG. 8 depending on the ratio of the dilute solution branched in the branch line (23) to the whole. In FIG. 8, it can be seen that the coefficient of performance COP has a peak value when 25% of the total diluted absorbent is branched into the branch line (23). It is generally known that the value of the coefficient of performance COP is 1.0 in a normal double-effect absorption refrigeration cycle, so the value of 1.5 or more obtained in the present embodiment is remarkably large. Is excellent. FIG. 8 shows that the coefficient of performance COP exceeds 1.53 in at least the range of 15% to 30%.
[0032]
FIG. 9 shows a schematic configuration of an absorption refrigeration cycle as a fourth embodiment of the present invention. In the present embodiment, portions corresponding to those of the previously described embodiment are denoted by the same reference numerals, and redundant description will be omitted. In the present embodiment, unlike the embodiment of FIG. 5, the branch line (23) is connected to the low-temperature solution heat exchanger (18) of the diluted absorption liquid line (21) in the same manner as in the embodiment of FIG. It branches off from the part between the solution heat exchanger (19) and then heat exchange in the drain heat exchanger (33). As shown in FIG. 10, the state change of the absorbing liquid in this embodiment is similar to the state change shown in FIG. That is, the states E1 to E7 are considered to correspond to the states B1 to B7 in FIG. 4, respectively.
[0033]
FIG. 11 shows a schematic configuration of an absorption refrigeration cycle as a fifth embodiment of the present invention. In this embodiment, the same reference numerals are given to portions corresponding to each of the embodiments described above, and redundant description will be omitted. In the present embodiment, the dilute absorbent fed from the high-pressure side absorber (12a) to the dilute absorbent line (21) by the absorbent pump (17) is sent from the solution heat exchanger (18) to the low-temperature generator (14). After that, the absorbent concentrated to the intermediate concentration is supplied to the high temperature generator (13) from the intermediate absorbent line (31) via the high temperature solution heat exchanger (19) by the absorbent pump (34). ing. The high-concentration absorbent concentrated in the high-temperature generator (13) is absorbed by the high-temperature solution heat exchanger (19) and the low-temperature solution heat exchanger (18) through the concentrated absorbent line (22). Container (12b). In the present embodiment, when the diluted absorption liquid returns, it is sequentially concentrated, and the order of concentration shown in FIG. 13 is reversed.
[0034]
FIG. 12 shows a state change of the absorbing liquid in the operation of the embodiment of FIG. F1 indicates the state of the outlet side of the high-temperature generator (13). F2 indicates the state of the absorbent at the intermediate portion between the high-temperature solution heat exchanger (19) and the low-temperature solution heat exchanger (18) in the concentrated absorbent line (22). F3 indicates the state of the absorbent at the inlet of the low-pressure side absorber (12b). From F1 to F3, the solution concentration does not change and the temperature decreases due to heat exchange in the high-temperature solution heat exchanger (19) and the low-temperature solution heat exchanger (18). In the low-pressure side absorber (12b), the water vapor as the refrigerant is absorbed by the absorbing liquid, the concentration is reduced, and the state changes to the state indicated by F4. Further, the refrigerant is absorbed by the high-pressure side absorber (12a), and the refrigerant is supplied to the low-temperature generator (14) by the absorption liquid pump (17) in a state shown by F5 in which the concentration is reduced. In the low-temperature generator (14), the concentration of the absorbing liquid is concentrated from the state shown by F7, and further concentrated by the absorbing liquid pump (34) to the concentration in the state F6 that is fed into the inlet side of the high-temperature generator (14). In this embodiment, since the absorption liquid is finally concentrated by the high-temperature generator (13), it can be concentrated to a high concentration at a high temperature. Even if the temperature of the low-pressure side absorber (12b) is not lowered much, a low vapor pressure can be obtained with a high-concentration absorbent, and a wide concentration range can be obtained from a plurality of absorption high-concentration sides to a low-concentration side. The coefficient can be improved.
[0035]
In each of the embodiments described above, the evaporator (11) and the absorber (12) are formed in two stages, respectively. However, the evaporator (11) and the absorber (12) may be formed in a multi-stage type having a larger number of stages. The efficiency of the operation of the absorption refrigeration cycle can be increased by increasing the concentration width, which is the difference between the concentration of the absorbent on the inlet side and the concentration of the absorbent on the outlet side.
[0036]
【The invention's effect】
As described above, according to the present invention, a part of the diluted absorbing solution sent from the absorber (12) to the high-temperature regenerator (13) is branched and sent to the low-temperature generator (14). To reduce the heating energy required in the high-temperature generator (13), improve the energy efficiency of the double-effect absorption cycle, and improve the coefficient of performance COP.
Further, the heat of the refrigerant sent from the low-temperature generator (14) to the condenser (15) is exchanged with the rare absorbing liquid branched off in the branch pipe (23) by the drain heat exchanger (33). The heat efficiency of the absorption refrigeration cycle can be further improved by effectively utilizing the heat energy of the absorption refrigeration cycle.
[0038]
Further, according to the present invention, the intermediate-concentration absorbent concentrated in the high-temperature generator (13) is combined with the diluted absorbent branched from the branch pipe line (23), and is fed into the low-temperature generator (14). The amount of the dilute absorbing liquid that needs to be heated by the generator (13) can be reduced, and the thermal efficiency can be improved.
[0040]
Further, according to the present invention, since the temperature of the diluted absorbent branched in the branch pipe (23) rises due to heat exchange in the low-temperature solution heat exchanger (18), the energy required for heating in the low-temperature regenerator (14) is increased. And the thermal efficiency as an absorption refrigeration cycle can be increased.
[0041]
According to the present invention, the coefficient of performance of the absorption cycle can be set to exceed 1.53 by setting the distribution ratio of the diluted rare absorbing solution to be 15 to 30%.
[Brief description of the drawings]
FIG. 1 is a piping diagram showing a schematic configuration of an absorption refrigeration cycle according to a first embodiment of the present invention.
FIG. 2 is a cycle diagram showing a state change of an absorbent in the embodiment of FIG.
FIG. 3 is a piping diagram showing a schematic configuration of an absorption refrigeration cycle according to a second embodiment of the present invention.
FIG. 4 is a cycle diagram showing a state change of the absorbing liquid of the embodiment of FIG.
FIG. 5 is a piping diagram showing a schematic configuration of an absorption refrigeration cycle according to a third embodiment of the present invention.
FIG. 6 is a cycle diagram showing a state change of an absorbent in the embodiment of FIG.
FIG. 7 is a cycle diagram showing a state change of the absorbing liquid when the temperature difference of the cooling water is increased in the embodiment of FIG.
FIG. 8 is a graph showing a relationship between a ratio of a rare absorbing liquid branched to a branch pipe (23) side and a coefficient of performance COP in the embodiment of FIG.
FIG. 9 is a piping diagram illustrating a schematic configuration of an absorption refrigeration cycle according to a fourth embodiment of the present invention.
FIG. 10 is a cycle diagram showing a state change of the absorbing liquid in the embodiment of FIG.
FIG. 11 is a piping diagram showing a schematic configuration of an absorption refrigeration cycle according to a fifth embodiment of the present invention.
FIG. 12 is a cycle diagram showing a state change of the absorbing liquid in the embodiment of FIG.
FIG. 13 is a piping diagram showing a schematic configuration of a conventional two-stage absorption double effect absorption refrigeration cycle.
FIG. 14 is a cycle diagram showing a state change of an absorbent in the absorption refrigeration cycle of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Evaporator 11a High pressure side evaporator 11b Low pressure side evaporator 12 Absorber 12a High pressure side evaporator 12b Low pressure side evaporator 13 High temperature generator 14 Low temperature generator 15 Condenser 17 Absorbent pump 18 Low temperature solution heat exchanger 19 High temperature solution Heat exchanger 21 Dilute absorbent line 22 Concentrated absorbent line 23 Branch line 24 Merging line 29 Cold water inlet 30 Cold water outlet 31 Intermediate absorbent line 32 Drain line 33 Drain heat exchanger

Claims

The high temperature generator (13), low temperature generator (14), condenser (15), absorber (12), evaporator (11), hot solution heat exchanger (19) and cold solution heat exchanger (18) In a double-effect absorption refrigerator configured to include:
The absorber (12) and the evaporator (11) are divided into a plurality of stages having different evaporation temperatures of the refrigerant,
A dilute absorbent line (21) for transporting dilute absorbent from the absorber (12) to the high temperature generator (13) via the low temperature solution heat exchanger (18) and the high temperature solution heat exchanger (19);
A branch line (23) for transporting a part of the diluted absorption liquid to the low temperature generator (14);
Drain heat for exchanging heat between the dilute absorption liquid transported in the branch line (23) and the refrigerant generated in the high temperature generator (13) and condensed in the low temperature generator (14) and transported to the condenser (15) An exchanger (33);
An absorption refrigerator comprising:

The absorption refrigeration according to claim 1, wherein the absorption liquid concentrated in the high-temperature generator (13) is joined to the branch pipe (23) and transported to the low-temperature generator (14). Machine.

The diluent line (21) branches from the dilute absorbent line (21) between the low temperature solution heat exchanger (18) and the high temperature solution heat exchanger (19). 3. The absorption refrigerator according to any one of 1 and 2.

The absorption refrigerator according to any one of claims 1 to 3, wherein a distribution ratio of the diluted absorption liquid to the branch pipe (23) is 15 to 30%.