JP4402238B2

JP4402238B2 - Operation method of regenerative refrigeration cycle

Info

Publication number: JP4402238B2
Application number: JP2000035816A
Authority: JP
Inventors: 広有柴; 誠司井上
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2000-02-14
Filing date: 2000-02-14
Publication date: 2010-01-20
Anticipated expiration: 2020-02-14
Also published as: JP2001227837A

Description

【０００１】
【発明の属する技術分野】
この発明は、蓄熱式冷凍サイクル及びその運転方法に関するものである。
【０００２】
【従来の技術】
図１４は、例えば特開平８−６１７９５号公報に示された従来の蓄熱システムの多段圧縮運転方法の装置図である。
【０００３】
図１４において、２０は低圧側圧縮機、２１は高圧側圧縮機、２２は凝縮器、２３は中間冷却器、２４、２８、３２は膨張弁、２５は蒸発器、２７、３１、３５は切替弁、３０は第２凝縮器、３３は蓄冷材冷却器、３６は蓄冷材、３９は蓄冷ポンプ、４０、４１、４２は温感筒である。
【０００４】
次に動作を図１４を用いて説明する。
夜間等の低負荷時は、図１４中実線矢印で示すように、凝縮器２２によって冷却された冷媒を、中間冷却器２３に送るとともに、その一部を切替弁２７を介して冷却管２９に送り、膨張弁２８で減圧して中間冷却器２３の冷却用媒体として中間冷却器２３内に送り、冷媒を冷却する。そして、中間冷却器２３において冷却に使用された冷媒は、高圧側圧縮機２１入口側の冷媒と合流してこれを冷却する。
【０００５】
他方、中間冷却器２３において冷却された冷媒の一部は、冷凍負荷に対応した開度だけ開かれた切替弁３５から膨張弁２４を介して蒸発器２５に送られ、ここで気化して所要の冷凍を行う。これと並行して冷媒の大部分は、ほぼ全開された切替弁３１から蓄冷材用管３４に送られ、膨張弁３２で減圧されて蓄冷材冷却器３３において内部の蓄冷材３６を冷却する。
【０００６】
次いで、昼間等の通常負荷運転時には、図中点線矢印で示すように、切替弁３１を閉じるとともに、蓄冷材ポンプ３９を駆動して、夜間時等に蓄冷された蓄冷材冷却器３３の蓄冷材３６を第２凝縮器３０に供給する。これにより、凝縮器２２から送られてきた冷媒は、第２凝縮器３０においてさらに冷却され、ほぼ全開とされた切替弁３５を介して膨張弁２４から蒸発器２５に送られ、ここで気化して昼間等の通常負荷に対応した冷凍を行う。
【０００７】
このように構成された多段冷凍装置及び多段冷凍方法によれば、低負荷時に中間冷却器２３を経た冷媒の一部またはそのほぼ全部によって蓄冷材３６を冷却し、通常負荷運転時に、蓄冷しておいた蓄冷材３６を第２凝縮器３０に供給して凝縮器２２出口の冷媒を冷却することにより、中間冷却器２３への冷却用冷媒の流量を減少させて、蒸発器２５に供給する冷媒の流量を増大させることができるため、通常負荷運転時に、蒸発器２５において実質的に冷凍に寄与する冷媒の流量を大幅に増加させることができ、よって通常負荷運転時における消費電力を大幅に削減することができるとともに、昼夜間等における消費電力の平準化と、消費電力の削減とを共に図ることができる。
【０００８】
【発明が解決しようとする課題】
従来の蓄熱システムの多段圧縮運転方法は、蒸発温度が−３０℃以下である冷凍装置を前提としており、常時多段圧縮運転することは性能的にも圧縮機の信頼性的にも良い。しかし例えば空調時等蒸発温度が０℃〜１０℃を想定すると、圧縮機の吐出側の冷媒圧力と吸入側の冷媒圧力との比である圧縮比は冷凍装置よりも小さくなり、多段圧縮運転にくらべて単段圧縮運転の方が実運転上のＣＯＰがよくなり、圧縮機信頼性もほとんど変わらない場合がある。
【０００９】
また、多段圧縮運転時の冷凍能力は単段圧縮運転と比較して約半分くらいになってしまう。例えば、１０ＨＰ室外機に圧縮機を２台搭載する場合、二段圧縮運転する場合は１０ＨＰ圧縮機を２台用意する必要があるが、単段圧縮運転する場合は５ＨＰ圧縮機を２台用意すればよく、常時多段圧縮運転することは設備コストの増大につながる。
【００１０】
この発明は、かかる問題点を解消するためになされたもので、蓄熱式冷凍サイクルにおいて、圧縮比が大きくなる場合の性能及び信頼性を確保するとともに、圧縮比が小さくなる場合も想定して、低設備コストで高性能な蓄熱式冷凍サイクル及びその運転方法を提供することを目的とする。
【００１１】
【課題を解決するための手段】
この発明に係る蓄熱式冷凍サイクルは、複数の圧縮機と、四方弁と、熱源側熱交換器と、複数の気液分離器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、状況に応じ、複数の圧縮機を用いて多段圧縮運転と単段圧縮運転とを選択して実行するものである。
【００１２】
また、複数の圧縮機と、四方弁と、熱源側熱交換器と、複数の中間冷却器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、有する負荷ユニットと、を備え、状況に応じ、複数の圧縮機を用いて多段圧縮運転と単段圧縮運転とを選択して実行するものである。
【００１３】
また、複数の圧縮機と、四方弁と、熱源側熱交換器と、エコノマイザと、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、状況に応じ、複数の圧縮機を用いて多段圧縮運転と単段圧縮運転とを選択して実行するものである。
【００１４】
また、多段圧縮運転する場合は使用する複数の圧縮機を直列に接続し、単段圧縮運転する場合は使用する複数の圧縮機を並列に接続するものである。
【００１５】
また、多段圧縮運転する場合に使用する各圧縮機の容量は、蓄冷時に多段圧縮運転する場合の各圧縮機の流量比に基づいて設定するものである。
【００１６】
また、所定の圧縮機は容量可変形の圧縮機であり、残りは容量一定形の圧縮機としたものである。
【００１７】
この発明に係る蓄熱式冷凍サイクルの運転方法は、蓄冷時は多段圧縮運転、蓄冷時以外の時は単段圧縮運転するものである。
【００１８】
また、複数の圧縮機の中で冷媒流れの最下流にある圧縮機の吐出部の冷媒圧力と、最上流にある圧縮機の吸入部の冷媒圧力を検出し、前記吐出冷媒圧力と前記吸入冷媒圧力の比である圧縮比が予め定めた閾値より小さい場合は、単段圧縮運転を選択し、圧縮比が前記所定値より大きい場合は、多段圧縮運転を選択し、現行運転と異なる圧縮方法を選択した場合は予め定めた制御時間経過後に圧縮方法を変更し、その後、予め定めた保護制御時間中は圧縮方法の変更を認めないものである。
【００１９】
この発明に係る蓄熱式冷凍サイクルは、圧縮機と、四方弁と、熱源側熱交換器と、膨張動力回収装置と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、蓄冷時に膨張動力回収装置を使用するものである。
【００２０】
また、圧縮機と、四方弁と、熱源側熱交換器と、高低圧熱交換器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、蓄冷時に高低圧熱交換器を使用するものである。
【００２１】
また、圧縮機と、四方弁と、熱源側熱交換器と、組成調整装置と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、冷媒が非共沸の混合冷媒の場合、蓄冷時に組成調整装置を用いて組成調整を行うものである。
【００２２】
【発明の実施の形態】
実施の形態１．
以下、この発明の実施の形態１を図面を参照して説明する。
図１〜４は実施の形態１を示す図で、図１は蓄熱システムの冷凍サイクルの回路図、図２は単段圧縮運転のＰ−ｈ線図、図３は多段圧縮運転のＰ−ｈ線図、図４は、圧縮比と、多段圧縮と単段圧縮の理論冷凍サイクル上のＣＯＰ比を示した図である。
図１において、１ａ，１ｂは圧縮機、２は四方弁、３は熱源側熱交換器（送風ファンを含む）、４ａは気液分離器、５ａ，５ｃ，５ｄは減圧装置、６は蓄熱槽、７は蓄熱槽伝熱管、８は蓄冷媒体、９は負荷側熱交換器（送風ファンを含む）、１０ａ〜１０ｋは開閉弁、１１はアキュムレータ、Ｘは熱源ユニット、Ｙは負荷ユニット、Ｚは蓄熱ユニットで、熱源ユニットＸと負荷ユニットＹと蓄熱ユニットＺとは冷凍サイクルを構成する。
【００２３】
単段圧縮を行う場合は、開閉弁１０ａ，１０ｂを開けて、開閉弁１０ｃを閉じ、圧縮機１ａ、１ｂの吸入側は開閉弁１０ａを介して連通し、また圧縮機１ａ、１ｂの吐出側は開閉弁１０ｂを介して連通する。この回路構成を並列接続構成と呼ぶことにする。一方、二段圧縮を行う場合は、開閉弁１０ａ，１０ｂを閉じ、開閉弁１０ｃを開けて、圧縮機１ａの吐出側は開閉弁１０ｃを介して圧縮機１ｂの吸入側に連通する。この圧縮機回路構成を直列接続構成と呼ぶことにする。
【００２４】
次に蓄冷時の単段圧縮運転、及び二段圧縮運転の動作について図１を用いて説明する。蓄冷時は開閉弁１０ｈを開、開閉弁１０ｊ、１０ｋ、１０ｉを閉にして、熱源ユニットＸと蓄熱ユニットＺで冷凍サイクルを構成する。
【００２５】
蓄冷時の単段圧縮運転の動作を説明する。
開閉弁１０ａ、１０ｂ、１０ｇを開、開閉弁１０ｃ、１０ｄ、１０ｆを閉にして、さらに減圧装置５ａを全閉にする。
【００２６】
そして、圧縮機１ａで圧縮されて吐出した高圧ガス冷媒は、開閉弁１０ｂを介して、圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒と合流して、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、開閉弁１０ｇを介し、減圧装置５ｃで減圧されて低圧２相状態になって蓄熱槽伝熱管７へと流入する。蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へ流入し、圧縮機１ｂの吸入側には開閉弁１０ａを介して流入する。一方、蓄熱槽６では蓄熱槽伝熱管７を流通する冷媒の吸熱作用により蓄冷媒体８の温度が低下し、さらに凝固温度に到達すると蓄熱槽伝熱管７のまわりに凝固しはじめる。
【００２７】
蓄冷時の二段圧縮運転の動作を説明する。
開閉弁１０ｃ、１０ｄ、１０ｆを開、開閉弁１０ａ、１０ｂ、１０ｇを閉にする。
【００２８】
そして、圧縮機１ａで圧縮されて吐出したガス冷媒は、開閉弁１０ｃを介した後、気液分離器４ａから流入する中圧飽和ガス冷媒が開閉弁１０ｄを介して合流して、圧縮機１ｂの吸入側に流入する。圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒は、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、減圧装置５ａで減圧された後、中圧二相冷媒となって気液分離器４ａに流入する。
【００２９】
気液分離器４ａで分離された中圧飽和ガス冷媒は開閉弁１０ｄを介して圧縮機１ｂの吸入側へ流入する一方、中圧飽和液冷媒は開閉弁１０ｆを介して減圧装置５ｃで減圧された後、低圧２相状態になって蓄熱槽伝熱管７へと流入する。蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へと流入する。一方、蓄熱槽６では蓄熱槽伝熱管７を流通する冷媒の吸熱作用により蓄冷媒体８の温度が低下し、さらに凝固温度に到達すると蓄熱槽伝熱管７のまわりに凝固しはじめる。
【００３０】
蓄冷利用冷房時の単段圧縮運転の動作を説明する。蓄冷利用冷房運転時は開閉弁１０ｉ、１０ｊ、１０ｋを開、開閉弁１０ｈを閉にして、熱源ユニットＸ、負荷ユニットＹ、蓄熱ユニットＺで冷凍サイクルを構成する。
【００３１】
開閉弁１０ａ、１０ｂ、１０ｇを開、開閉弁１０ｃ、１０ｄ、１０ｆを閉にして、さらに減圧装置５ａを全閉にする。
【００３２】
そして、圧縮機１ａで圧縮されて吐出した高圧ガス冷媒は、開閉弁１０ｂを介して、圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒と合流して、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、開閉弁１０ｇを介し、減圧装置５ｃを流通するが、ここでは減圧されずに蓄熱槽伝熱管７へと流入する。
【００３３】
蓄熱槽伝熱管７では管内を流通する冷媒温度より低温の蓄冷媒体８との熱交換により凝縮されて、蓄熱槽伝熱管７出口では過冷却した高圧液冷媒となって流出し、開閉弁１０ｉ、開閉弁１０ｋを介して、減圧装置５ｄへ流通し、ここで減圧されて低圧二相冷媒状態で負荷側熱交換器９へ流入する。負荷側熱交換器９では管内を流通する冷媒温度より高温の周囲空気との熱交換により蒸発されて、負荷側熱交換器９出口では低圧ガス冷媒となって流出し、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へ流入し、圧縮機１ｂの吸入側には開閉弁１０ａを介して流入する。
【００３４】
二段圧縮に使用する圧縮機１ａ、１ｂの容量は蓄冷時の二段圧縮運転を想定して決定するが、その具体的な決定方法の手順の一例を以下に示す。
対象冷媒は混合冷媒Ｒ４０７Ｃとし、説明を簡単にするために、組成はＲ３２：Ｒ１２５：Ｒ１３４ａ＝２３％：２５％：５２％一定とし、冷凍サイクルにおいて凝縮器出口は飽和液状態、蒸発器出口は飽和ガス状態とし、圧力損失は減圧装置以外の箇所では無いとする。また、圧縮は断熱圧縮とし、膨張は等エントロピ変化とする。
【００３５】
次に計算条件として、蓄冷時の冷凍サイクルにおける高圧を１．６［ＭＰａ］、低圧を０．４［ＭＰａ］として、中圧は高段側の圧縮比と低段側の圧縮比を一定とする値とし、０．８［ＭＰａ］とする。また物性計算にはＲｅｆＰｒｏｐＶｅｒ．６を使用する。
【００３６】
以上の条件下における単段圧縮、二段圧縮の計算結果を図２、図３のＰ−ｈ線図に示す。
図２の蒸発器の入口と出口の比エンタルピ差Δｈｅ１＝１５２．４［ｋＪ／ｋｇ］
図３の蒸発器の入口と出口の比エンタルピ差Δｈｅ２＝１９１．１［ｋＪ／ｋｇ］
図３の気液分離比＝Δｈｇ：Δｈｌ＝１９．３％：８０．７％
単段圧縮運転時と同等冷凍能力を二段圧縮運転時でも確保するには、単段圧縮機の容量１に対して、下段圧縮機の容量はΔｈｅ１／Δｈｅ２の式で求めることができる。計算すると０．７９７となる。一方、上段圧縮機の容量は下段圧縮機容量と気液分離比を用いて求めることができる。計算すると上段圧縮機の容量は０．９８８となる。あとは、冷凍サイクルの負荷上限値を考慮して、上段と下段の圧縮機容量比を保持しながら比例設計する。
【００３７】
尚、圧縮機容量は圧縮機内のストロークボリュームの容積で調整してもいいし、インバータを搭載して、圧縮機の回転数で調整してもいい。尚、この場合、一方の圧縮機をインバータを搭載した運転容量可変の圧縮機とし、もう片方を運転容量一定の圧縮機にして運転すれば、インバータを１つ減らすことができて設備コスト低減につながる。
【００３８】
また、冷媒種類がＲ４０７Ｃ以外のものを使用する場合も、単段圧縮運転、二段圧縮運転の動作方法は同じである。
【００３９】
二段圧縮と単段圧縮の長所を示す。
二段圧縮の長所はＣＯＰが良く、また１台当たりの圧縮比が小さいので、軸受け等にかかる力が小さいため、圧縮機の信頼性が高いことであり、冷凍サイクル全体の圧縮比が大きいほど、この特徴は顕著になる。例を以下に示す。
図２、図３において、二段圧縮と単段圧縮における同一冷凍能力下での理論冷凍サイクル上のＣＯＰを計算する。ＣＯＰ＝冷凍能力量［ｋＪ／ｈ］／圧縮機入力［ｋＪ／ｈ］で求まる。
単段圧縮の場合の冷媒流量Ｇ＝１［ｋｇ／ｈ］とすると、
・冷凍能力Ｑｒ＝Ｇ×Δｈｅ１＝１５２．４［ｋＪ／ｈ］
・圧縮機入力Ｗ＝Ｇ×Δｈｗ１＝３４．０［ｋＪ／ｈ］
・ＣＯＰ＝Ｑｒ／Ｗ＝４．４８
となる。
【００４０】
一方、多段圧縮の場合、単段圧縮時と同等冷凍能力を確保するための冷媒流量はＧ下段＝０．７９７［ｋｇ／ｈ］、Ｇ上段＝０．９８８［ｋｇ／ｈ］なので、
・圧縮機上段入力Ｗ上段＝Ｇ上段×Δｈｗ２＝１６．３［ｋＪ／ｋｇ］
・圧縮機下段入力Ｗ下段＝Ｇ下段×Δｈｗ３＝１３．５［ｋＪ／ｋｇ］
・ＣＯＰ＝Ｑｒ／（Ｗ上段＋Ｗ下段）＝５．１１
となり、単段圧縮のＣＯＰと比較して約１４％向上する。
【００４１】
また、圧縮比が大きいと、圧縮機吐出ガス冷媒温度が上昇して、冷凍機油の劣化が促進されて、圧縮機が故障したり冷媒が熱分解する可能性があり、圧縮機の信頼性が低下する。二段圧縮にして圧縮比を小さくすることは信頼性の向上につながる。
【００４２】
一方、単段圧縮の長所は冷凍能力量が大きいことである。例を以下に示す。
図２、図３において、２台の圧縮機の容量を０．７９７、０．９８８とすると、単段圧縮と二段圧縮を行った場合の冷凍能力は、
・単段圧縮の冷凍能力Ｑｒ＝（０．７９７＋０．９８８）・Δｈｅ１＝２７２．０［ｋＪ／ｈ］
・二段圧縮の冷凍能力Ｑｒ＝０．９８８・Δｈｅ２＝１５２．４［ｋＪ／ｈ］
となり、単段圧縮時は、二段圧縮時に対して１７９％能力増加を図ることができる。
同一容量の２台の圧縮機を用いて単段圧縮した場合の全冷凍能力は各圧縮機容量×台数で表すことができるが、二段圧縮した場合の全冷凍能力は約１台分の圧縮機容量となり、単段圧縮と比較して概ね半分の冷凍能力になる。例えば、定格１０ＨＰの室外機に５ＨＰ用の圧縮機が２台搭載されている場合、２台圧縮機を単段圧縮運転した場合は全冷凍能力として１０ＨＰを確保できるが、二段圧縮した場合は全冷凍能力として約５ＨＰで１０ＨＰ容量を確保することはできない。
【００４３】
また、圧縮比が小さい場合は、二段圧縮と単段圧縮との理論冷凍サイクル上のＣＯＰの差が小さくなる。図４に低圧を０．４［ＭＰａ］一定とした時の圧縮比と、理論冷凍サイクル上の二段圧縮の単段圧縮に対するＣＯＰの向上比率の関係について示す。圧縮比が小さくなると、実サイクル上では配管圧力損失や、気液分離器での熱ロス、圧縮機のインバータの発熱ロス、圧縮機単体の特性などを考慮すると、図４のように単段圧縮の方がＣＯＰが良くなる運転条件がある。
【００４４】
次に蓄冷運転時の必要圧縮機容量について説明する。昼間の蓄冷利用冷房運転において、蓄冷熱を利用する割合は、昼間の全負荷量の約２０％〜４０％分であり、残りは圧縮機を運転して賄う方式が一般的である。仮に昼間の全負荷量を定格冷房能力×運転時間と想定する。さらに、昼間の冷房時間と夜間の蓄冷時間を同じとすると、蓄冷時に必要な冷凍能力は、定格冷房時の２０％〜４０％である。また、冷房時と蓄冷時の蒸発温度の違いや熱源側熱交換器３の周囲空気温度の違い、すなわち昼間と夜間の外気温の違いを考慮すると蓄冷時に必要な圧縮機容量は、冷房時の半分以下である。
【００４５】
昼間の蓄冷利用冷房時と、蓄冷時において、必要な圧縮機容量が２倍以上違うことを考慮すると、蓄冷利用冷房時は要求される冷凍能力が大きく、かつ圧縮比が小さいので、冷凍能力量確保を重視した単段圧縮運転を行ない、蓄冷時は要求される冷凍能力が小さく、かつ蒸発温度が低いため圧縮比が大きくなる傾向があるので、ＣＯＰが良く、圧縮機の信頼性が高い多段圧縮運転を行うようにすれば、低設備コストで低運転コストなシステムを実現できる。
【００４６】
また、蓄冷など要求される冷凍能力量が小さい時に圧縮比が小さくなって、実冷凍サイクル上で単段圧縮運転のＣＯＰが二段圧縮運転のＣＯＰよりよくなる場合は、二段圧縮運転から１台単段運転にすれば、低コストで高ＣＯＰ運転を実現することができる。
【００４７】
常時二段圧縮運転すると、例えば定格１０ＨＰの機種に１０ＨＰ用圧縮機を２台搭載する必要があり、設備コストが高くなる。蒸発温度が−３０℃になる例えば冷凍用機器ではなく、蒸発温度が−１０℃以上を想定している機器であれば、単段圧縮運転と二段圧縮運転を切替えれるようにして、５ＨＰ圧縮機を２台搭載する方が設備コスト上有効である。
【００４８】
以上より、二段圧縮と単段圧縮の長所を考慮して切替え運転することは設備コスト、ＣＯＰ向上による運転コストを低減する上で大いに有効である。
【００４９】
二段圧縮と単段圧縮の運転切替方法の一例として、昼間の冷房運転時は単段圧縮運転して、夜間の蓄冷時は多段圧縮運転する。
【００５０】
二段圧縮と単段圧縮の運転切替方法の別の一例として、一番高圧となる圧縮機の吐出側の圧力と、一番低圧になる圧縮機の吸入側の圧力を何らかの手段で検知して、その圧縮比が予め定めた閾値を超える場合は、二段圧縮を選択し、閾値を超えない場合は単段圧縮を選択する。
【００５１】
二段圧縮と単段圧縮の運転切替方法の別の一例として、凝縮器の凝縮温度と蒸発器の蒸発温度を何らかの方法で検知して、それらの値から高圧、低圧を算出し、その圧力比が予め定めた閾値を超える場合は、二段圧縮を選択し、閾値を超えない場合は単段圧縮を選択する。
【００５２】
閾値は、圧縮比とＣＯＰの関係で単段圧縮と二段圧縮の優位性が逆転する点を定める。尚ＣＯＰは、理論冷凍サイクル上の理論ＣＯＰではなく、実サイクル上の圧力損失や熱ロスや圧縮機単体の性能特性を考慮した実ＣＯＰで検討する。この閾値が正しいことを計算だけではなく実機試験で確認できれば尚良いことは言うまでもない。
【００５３】
前記の冷媒圧力を検知する一手段として、圧縮機１ａの吸入配管に圧力センサを設ける一方、圧縮機１ｃの吐出配管に圧力センサを設けて各圧力を検知する例がある。また熱源側熱交換器３と負荷側熱交換器９の二相冷媒流通部にそれぞれ温度センサを設けて凝縮温度と蒸発温度を検知する冷がある。
【００５４】
運転中は予め定めた検知時間毎に、冷凍サイクルの吐出圧と吸入圧、或いは凝縮温度と蒸発温度から算出する高圧と低圧を検知して圧縮比或いは圧力比を求め、前記閾値と比較して大きいか、小さいかを判断して単段圧縮か二段圧縮のどちらかを選択する。そして現行の圧縮方法と比較して、変更する必要がある場合は、変更する。
【００５５】
検知時間間隔は、アクチュエータ変更後に冷凍サイクルが安定するまでの時間を考慮して設定するが、冷凍サイクルの規模、延長配管長により大きく異なるので、それぞれの条件に最も合う時間を見つけて設定する。
また過度な圧縮方法の変更は、圧力変化による圧縮機損傷や寿命の短縮化の可能性があることから、圧縮方法を変更後はある一定間隔の間は圧縮方法を変更しないと定めることや、１回の起動から停止までの間の圧縮方法の変更回数を制限することも冷凍サイクルの信頼性上有効である。
【００５６】
多段圧縮運転と単段圧縮運転の切替については蓄熱時と蓄熱利用暖房運転時にも適用できる。ここでは説明を省略する。
【００５７】
蓄熱ユニットの蓄熱槽は従来のアイスオンコイルのスタティック氷蓄熱槽であれば適用できるため、リニューアル時に従来の蓄熱槽を使用して冷媒回路を組むことは可能である。
【００５８】
以上により、実施の形態１で示した蓄熱式冷凍サイクルを使用すれば、複数の圧縮機と、四方弁と、熱源側熱交換器と、複数の気液分離器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットで構成する冷媒回路において、要求されている冷凍能力や圧縮比を検知して、複数の圧縮機で単段圧縮運転するか多段圧縮運転するかを選択できる回路構成、運転方法を採用することで、設備コストの低減とＣＯＰ向上による運転コストの低減を図ることができる。
【００５９】
実施の形態２．
以下、この発明の実施の形態２を図面を参照して説明する。
図５は実施の形態２を示す図で、蓄熱システムの冷凍サイクルの回路図である。図５において、１ａ，１ｂは圧縮機、２は四方弁、３は熱源側熱交換器（送風ファンを含む）、４ｂは中間冷却器、５ａ，５ｃ，５ｄは減圧装置、６は蓄熱槽、７は蓄熱槽伝熱管、８は蓄冷媒体、９は負荷側熱交換器（送風ファンを含む）、１０ａ〜１０ｋは開閉弁、１１はアキュムレータ、Ｘは熱源ユニット、Ｙは負荷ユニット、Ｚは蓄熱ユニットで、熱源ユニットＸと負荷ユニットＹと蓄熱ユニットＺは冷凍サイクルを構成する。
【００６０】
次に蓄冷時の単段圧縮運転、及び二段圧縮運転の動作について図５を用いて説明する。
蓄冷時は開閉弁１０ｈを開、開閉弁１０ｉ、１０ｊ、１０ｋを閉にして、熱源ユニットＸと蓄熱ユニットＺで冷凍サイクルを構成する。
【００６１】
蓄冷時の単段圧縮運転の動作を説明する。
開閉弁１０ａ、１０ｂ、１０ｆを開、開閉弁１０ｃ、１０ｄ、１０ｇを閉にして、さらに減圧装置５ａを全閉にする。
【００６２】
そして、圧縮機１ａで圧縮されて吐出した高圧ガス冷媒は、開閉弁１０ｂを介して、圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒と合流して、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、及び高圧二相冷媒となって流出し、中間冷却器４ｂに流入するものの、ここでは熱交換をせず、開閉弁１０ｆを介し、減圧装置５ｃにて減圧して蓄熱槽伝熱管７へと流入する。蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へ流入し、圧縮機１ｂの吸入側には開閉弁１０ａを介して流入する。蓄熱槽６で起こる現象は実施の形態１の蓄冷時と同様なので説明は省略する。
【００６３】
蓄冷時の二段圧縮運転の動作を説明する。
開閉弁１０ｃ、１０ｄ、１０ｆを開、開閉弁１０ａ、１０ｂ、１０ｇを閉にする。
【００６４】
そして、圧縮機１ａで圧縮されて吐出したガス冷媒は、開閉弁１０ｃを介して後、中間冷却器４ｂから流入する中圧ガス冷媒或いは中圧二相冷媒が開閉弁１０ｄを介して合流して、圧縮機１ｂの吸入側に流入する。圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒は、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、途中分岐して、一方はそのまま中間熱交換器４ｂ内伝熱管へ流入し、他方は減圧装置５ａで減圧された後、中圧二相冷媒となって中間冷却器４ｂに流入する。
【００６５】
中間冷却器４ｂ内伝熱管へ流入した高圧液冷媒、或いは高圧二相冷媒の冷媒温度に対して、中間冷却器４ｂ内の中圧冷媒温度は低いため、高圧液冷媒、或いは高圧二相冷媒はここでさらに凝縮して高圧液冷媒として流出した後、開閉弁１０ｆを介して、減圧装置５ｃで減圧して蓄熱槽伝熱管７へと流入する。
【００６６】
一方、中間冷却器４ｂの容器内に流入した中圧二相冷媒は蒸発して中圧ガス冷媒、或いは中圧二相冷媒となり、開閉弁１０ｄを介して、圧縮機１ａの吐出ガス冷媒と合流して圧縮機１ｂの吸入側へと流入する。
【００６７】
蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へと流入する。蓄熱槽６で起こる現象は実施の形態１の蓄冷時と同様なので説明は省略する。
【００６８】
二段圧縮に使用する圧縮機の容量は蓄冷運転を想定して決定するが、その具体的決定方法の手順は実施の形態１と同様なので説明を省略する。
【００６９】
また、冷媒種類がＲ４０７Ｃ以外のものを使用する場合も、単段圧縮運転、二段圧縮運転の動作方法は同じである。
【００７０】
二段圧縮と単段圧縮の切替運転を行うことで冷凍サイクルの設備コストを低減し、ＣＯＰ向上による運転コストを低減できることは実施の形態１に説明したのでここでは省略し、また圧縮方法の切替方法についても実施の形態１と同様なので説明を省略する。
【００７１】
以上により、実施の形態２で示した蓄熱式冷凍サイクルを使用すれば、複数の圧縮機と、四方弁と、熱源側熱交換器と、複数の中間冷却器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットで構成する冷媒回路において、要求されている冷凍能力や圧縮比を検知して、複数の圧縮機で単段圧縮運転するか多段圧縮運転するかを選択できる回路構成、運転方法を採用することで、設備コストの低減とＣＯＰ向上による運転コストの低減を図ることができる。
【００７２】
実施の形態３．
以下、この発明の実施の形態３を図面を参照して説明する。
図６は実施の形態３を示す図で、蓄熱システムの冷凍サイクルの回路図である。図６において、１ａ，１ｂは圧縮機、２は四方弁、３は熱源側熱交換器（送風ファンを含む）、４ｃはエコノマイザ、５ｃ，５ｄは減圧装置、６は蓄熱槽、７は蓄熱槽伝熱管、８は蓄冷媒体、９は負荷側熱交換器（送風ファンを含む）、１０ａ〜１０ｋは開閉弁、１１はアキュムレータ、Ｘは熱源ユニット、Ｙは負荷ユニット、Ｚは蓄熱ユニットで、熱源ユニットＸと負荷ユニットＹと蓄熱ユニットＺは冷凍サイクルを構成する。
【００７３】
次に蓄冷時の単段圧縮運転、及び二段圧縮運転の動作について図６を用いて説明する。蓄冷時は開閉弁１０ｈを開、開閉弁１０ｉ、１０ｊ、１０ｋを閉にして、熱源ユニットＸと蓄熱ユニットＺで冷凍サイクルを構成する。
【００７４】
蓄冷時の単段圧縮運転の動作を説明する。
開閉弁１０ａ、１０ｂ、１０ｇを開、開閉弁１０ｃ、１０ｄ、１０ｅ、１０ｆを閉にする。
【００７５】
そして、圧縮機１ａで圧縮されて吐出した高圧ガス冷媒は、開閉弁１０ｂを介して、圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒と合流して、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、開閉弁１０ｇを介し、減圧装置５ｃにて減圧して蓄熱槽伝熱管７へと流入する。蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へ流入し、圧縮機１ｂの吸入側には開閉弁１０ａを介して流入する。蓄熱槽６で起こる現象は実施の形態１の蓄冷時と同様なので説明は省略する。
【００７６】
蓄冷時の二段圧縮運転の動作を説明する。
開閉弁１０ｃ、１０ｄ、１０ｅ、１０ｆを開、開閉弁１０ａ、１０ｂ、１０ｇを閉にする。この時、圧縮機１ａの吐出側は開閉弁１０ｃを介して圧縮機１ｂの吸入側に連通する。
【００７７】
そして、圧縮機１ａで圧縮されて吐出したガス冷媒は、開閉弁１０ｃを介して後、エコノマイザ４ｃから流入する中圧飽和ガス冷媒が開閉弁１０ｄを介して合流して、圧縮機１ｂの吸入側に流入する。圧縮機１ｂで圧縮されて吐出した高圧ガス冷媒は、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、開閉弁１０ｅを介してエコノマイザ４ｃへ流入後、減圧した後気液分離した中圧飽和ガス冷媒は開閉弁１０ｄを介して圧縮機１ｂの吸入側へ流入する一方、残った中圧飽和液冷媒はさらに減圧して低圧二相冷媒となり開閉弁１０ｆを介して蓄熱槽伝熱管７へと流入する。
【００７８】
蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して、圧縮機１ａの吸入側へと流入する。蓄熱槽６で起こる現象は実施の形態１の蓄冷時と同様なので説明は省略する。
【００７９】
二段圧縮に使用する圧縮機の容量は蓄冷運転を想定して決定するが、その具体的決定方法の手順は実施の形態１と同様なので説明を省略する。
【００８０】
また、冷媒種類がＲ４０７Ｃ以外のものを使用する場合も、単段圧縮運転、二段圧縮運転の動作方法は同じである。
【００８１】
二段圧縮と単段圧縮の切替運転を行うことで冷凍サイクルの設備コストを低減し、ＣＯＰ向上による運転コストを低減できることは実施の形態１に説明したのでここでは省略し、また圧縮方法の切替方法についても実施の形態１と同様なので説明を省略する。
【００８２】
以上により、実施の形態３で示した蓄熱式冷凍サイクルを使用すれば、複数の圧縮機と、四方弁と、熱源側熱交換器と、エコノマイザと、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットから構成する冷媒回路において、要求されている冷凍能力や圧縮比を検知して、複数の圧縮機で単段圧縮運転するかか多段圧縮運転するかを選択できる回路構成、運転方法を採用することで、設備コストの低減とＣＯＰ向上による運転コストの低減を図ることができる。
【００８３】
実施の形態４．
以下、この発明の実施の形態４を図面を参照して説明する。
図７〜１０は実施の形態４を示す図で、図７，８は蓄熱システムの冷凍サイクル概略図、図９はエジェクタ概略図、図１０はＰ−ｈ線図である。
図７において、１は圧縮機、２は四方弁、３は熱源側熱交換器（送風ファンを含む）、５ｃ，５ｄは減圧装置、６は蓄熱槽、７は蓄熱槽伝熱管、８は蓄冷媒体、９は負荷側熱交換器（送風ファンを含む）、１０ａ〜１０ｋは開閉弁、１２は気液分離器、１３はエジェクタ、Ｘは熱源ユニット、Ｙは負荷ユニット、Ｚは蓄熱ユニットで、熱源ユニットＸと負荷ユニットＹと蓄熱ユニットＺは冷凍サイクルを構成する。
【００８４】
次に蓄冷時の動作について図７を用いて説明する。
蓄冷時は開閉弁１０ｆを開、開閉弁１０ｉ、１０ｊ、１０ｋを閉にして、熱源ユニットＸと蓄熱ユニットＺで冷凍サイクルを構成する。
【００８５】
開閉弁１０ｂ、１０ｄ、１０ｅを開、開閉弁１０ａ、１０ｃを閉にする。圧縮機１で圧縮されて吐出した高圧ガス冷媒は、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、開閉弁１０ｂを介し、エジェクタ１３へと流入する。エジェクタ１３では図９のノズル部で当エントロピ変化で減圧した低圧二相冷媒に吸入部から低圧ガス冷媒が流入し、デフューザ部で昇圧した後、中圧二相冷媒状態で気液分離器１２へ流入する。本動作の圧力変化を図１０に示す。
【００８６】
ここで気液分離した中圧飽和ガス冷媒は開閉弁１０ｄを介して圧縮機１吸入側へ流入し、中圧飽和液冷媒は開閉弁１０ｅを介して減圧装置５ｃへ流入し、ここで減圧した後、低圧二相冷媒状態で蓄熱槽伝熱管７へと流入する。蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｆを介してエジェクタ吸入部１８へと流入する。蓄熱槽６で起こる現象は実施の形態１の蓄冷時と同様なので説明は省略する。
【００８７】
また図８のように、開閉弁１０ａを有する吸入配管の一端を気液分離器に接続すると、畜冷運転以外ではアキュムレータとして使用できて設備コストの低減を図ることができる。畜冷時は開閉弁１０ｂ、１０ｌを開けて、開閉弁１０ａを閉じる。畜冷運転以外では、開閉弁１０ａを開いて、開閉弁１０ｂ、１０ｌを閉じる。
【００８８】
エジェクタ１３は蓄冷時のみ使用し、その他の運転時はエジェクタ１３及び気液分離器１２を使用しない。
エジェクタ１３の効果について簡単に示す。
高圧液冷媒を低圧二相冷媒にする膨張過程において、従来の減圧装置で減圧膨張すると、等エンタルピ変化のため、膨張エネルギーを冷凍サイクル外へ放出していることになり無駄である。一方、エジェクタ１３は断熱膨張、即ち等エントロピ変化のためその分膨張エネルギーが低減しないため、冷凍サイクルの冷凍能力が向上する。
【００８９】
エジェクタ１３は蒸発器温度が低いほど膨張エネルギーの回収率が大きくなり有効なので、蓄冷時のみに適用する。
エジェクタ１３は断熱熱落差をノズルにて運動エネルギーに変換し、エジェクタ吸引部１８から吸引流を吸引して圧縮機１の吸入圧力を上昇させる圧縮仕事を行う。駆動流のエネルギーと吸引流の圧縮仕事の比ηをエジェクタ効率と定義している。例えばエジェクタ効率を０．５とすれば、蓄冷材に水を使用して蒸発温度が−１０℃とした蓄冷時に、蓄熱槽伝熱管内冷媒圧力より吸入圧力を９．８０６６５×１０４［Ｐａ］高くすることは理論上は可能である。一方、蒸発温度が１０℃くらいの場合は、吸入圧力はその半分以下の分しか上昇しないので、実サイクルでは他の圧力損失の影響を受けて、エジェクタ効果が消滅する。
【００９０】
以上により、実施の形態４で示した蓄熱式冷凍サイクルを使用すれば、圧縮機と、四方弁と、熱源側熱交換器と、エジェクタと気液分離器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する熱源側ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷側ユニットで構成する冷媒回路において、蓄冷時に膨張動力回収装置を用いた運転することで、従来捨てていた膨張エネルギーを有効に活用して蓄冷運転ＣＯＰを向上することができる。
【００９１】
実施の形態５．
以下、この発明の実施の形態５を図面を参照して説明する。
図１１，１２は実施の形態５を示す図で、図１１は蓄熱システムの冷凍サイクルの回路図、図１２は蒸発器入口、出口、高低差熱交換器出口の比エンタルピを示す図である。
図１１において、１は圧縮機、２は四方弁、３は熱源側熱交換器（送風ファンを含む）、５ｃ，５ｄは減圧装置、６は蓄熱槽、７は蓄熱槽伝熱管、８は蓄冷媒体、９は負荷側熱交換器（送風ファンを含む）、１０ｅ〜１０ｋは開閉弁、１１はアキュムレータ、１５は高低圧熱交換器、Ｘは熱源ユニット、Ｙは負荷ユニット、Ｚは蓄熱ユニットで、熱源ユニットＸと負荷ユニットＹと蓄熱ユニットＺは冷凍サイクルを構成する。
【００９２】
次に蓄冷時における高低圧熱交換器１５を組込んだ冷媒回路の動作について図１１を用いて説明する。
蓄冷時は開閉弁１０ｉ、１０ｊ、１０ｋを閉にして、熱源ユニットＸと蓄熱ユニットＺで冷凍サイクルを構成する。
【００９３】
開閉弁１０ｅ、１０ｆを開にする。圧縮機１で圧縮されて吐出した高圧ガス冷媒は、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、高低圧熱交換器１５へ流入する。ここで低圧冷媒と熱交換してさらに凝縮して過冷却した高圧液冷媒として流出し、開閉弁１０ｅを介し、減圧装置５ｃへ流入し、ここで減圧した後、低圧二相冷媒状態で蓄熱槽伝熱管７へと流入する。
【００９４】
蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｆを介して高低圧熱交換器１５へ流入し、ここで高圧冷媒と熱交換して蒸発し、低圧過熱ガスとしてアキュムレータ１１を介して圧縮機１の吸入側へ流入する。蓄熱槽６で起こる現象は実施の形態１の蓄冷時と同様なので説明は省略する。
【００９５】
高低圧熱交換器１５は蓄冷時のみ使用し、その他の運転時は使用しない。蓄冷時だけ使用する理由を説明する。
蒸発器出口の冷媒温度が周囲空気より低い温度の場合、冷媒は圧縮機１の吸入側へ至る経路の途中で周囲空気に放熱し、冷媒は過熱ガスとなる。蓄冷時は、特に蒸発器出口の冷媒温度が低く、周囲空気へ放出する熱量が無視できない。この周囲へ無駄に放出していた冷熱を冷凍サイクルの高圧液側で回収すれば、冷凍サイクルの冷凍能力が増加する。
【００９６】
例えば、冷房時の蒸発器出口温度を１０℃、蓄冷時の蒸発器出口温度を−１０℃、いずれも飽和ガス状態として、周囲空気温度を２５℃とする。また高低圧熱交換器出口温度は周囲空気温度−５［℃］、即ち２０℃とする。
【００９７】
対象冷媒をＲ４０７Ｃとし、循環組成を封入組成であるＲ３２：Ｒ１２５：Ｒ１３４ａ＝２３％：２５％：５２％とする。尚物性計算はＲｅｆｐｒｏｐＶｅｒ．６を用いることとする。
また蒸発器の入口乾き度を０．２として、蒸発器入口、出口、高低差熱交換器出口の比エンタルピの値を図１２に示す。
【００９８】
図１２より、高低差熱交換器の部分の占める熱交換量割合ηを計算する。
・冷房η＝（ｈｈｅｘｏｕｔ−ｈｅｏｕｔ）／（ｈｈｅｘｏｕｔ−ｈｅｉｎ）＝４．１％
・蓄冷η＝（ｈｈｅｘｏｕｔ−ｈｅｏｕｔ）／（ｈｈｅｘｏｕｔ−ｈｅｉｎ）＝１２．４％
となる。蒸発器で熱交換した全熱量にうち、前記計算結果分の熱は、従来は周囲空気に捨てていたものであるが、冷凍サイクルの高圧液側で回収すればその分、冷凍能力を増加することができる。
その回収熱量は、蒸発温度が低いほど大きくなり、高低差熱交換器における冷熱回収効果は冷房時より蓄冷時に顕著に効果があることが解る。
また、蓄熱槽伝熱管出口が低圧二相冷媒の場合は、冷媒の潜熱分、熱交換量が増加して、冷熱回収効果はさらに大きくなる。
【００９９】
一方、冷熱を回収した高圧液冷媒側は、熱交換により液冷媒の過冷却度が大きくなり、その結果、蒸発器入口と出口の比エンタルピ差を大きくして冷凍能力を向上することができる。
【０１００】
以上により、実施の形態５で示した蓄熱式冷凍サイクルを使用すれば、圧縮機と、四方弁と、熱源側熱交換器と、高低圧熱交換器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、を有する負荷ユニットで構成される冷媒回路において、蓄冷時に高低圧熱交換器を用いることで、従来蒸発器になる蓄熱槽伝熱管の出口から圧縮機吸入側への経路の途中で周囲空気に放出していた冷熱を冷凍サイクルの高圧液側で回収することで、冷凍能力を向上させることができる。
【０１０１】
実施の形態６．
以下、この発明の実施の形態５を図面を参照して説明する。
図１３は実施の形態６を示す図で、蓄熱システムの冷凍サイクル概略図である。
図１３において、１は圧縮機、２は四方弁、３は熱源側熱交換器（送風ファンを含む）、５ａ，５ｃ，５ｄは減圧装置、６は蓄熱槽、７は蓄熱槽伝熱管、８は蓄冷媒体、９は負荷側熱交換器（送風ファンを含む）、１０ｅ，１０ｈ〜１０ｋは開閉弁、１１はアキュムレータ、１５は高低圧熱交換器、１７は気液分離器、Ｘは熱源ユニット、Ｙは負荷ユニット、Ｚは蓄熱ユニットで、熱源ユニットＸと負荷ユニットＹと蓄熱ユニットＺは冷凍サイクルを構成する。
【０１０２】
次に蓄冷時において、組成調整器としての高低圧熱交換器１５、及び気液分離器１７を組込んだ冷媒回路の動作について図１１を用いて説明する。
蓄冷時は開閉弁１０ｈを開、開閉弁１０ｉ、１０ｊ、１０ｋを閉にして、熱源ユニットＸと蓄熱ユニットＺで冷凍サイクルを構成する。
【０１０３】
開閉弁１０ｅを開にする。圧縮機１で圧縮されて吐出した高圧ガス冷媒は、四方弁２を介して、熱源側熱交換器３へ流入する。熱源側熱交換器３では熱交換器内を流通する冷媒温度に対して低温の周囲空気との熱交換により凝縮されて、熱源側熱交換器３出口では高圧液冷媒、或いは高圧二相冷媒となって流出し、気液分離器１７へ流入し、ここで分離された高圧ガス冷媒は高低圧熱交換器１５へ流入し、ここで低圧冷媒と熱交換して凝縮し、高圧液冷媒として流出し、開閉弁１０ｅを介し、減圧装置５ｃで減圧した後、低圧二相冷媒状態で蓄熱槽伝熱管７へと流入する。
【０１０４】
蓄熱槽伝熱管７では管内を流通する冷媒温度より高温の蓄冷媒体８との熱交換により蒸発されて、蓄熱槽伝熱管７出口では低圧ガス冷媒となって流出し、開閉弁１０ｈ、四方弁２、アキュムレータ１１を介して圧縮機１の吸入側へ流入する。
【０１０５】
一方、気液分離器１７で分離された高圧飽和液冷媒は減圧装置５ａで減圧して低圧二相冷媒となって高低圧熱交換器１５へ流入する。ここで高圧冷媒と熱交換して蒸発して低圧ガス冷媒となり、アキュムレータ１１へ流入する。
【０１０６】
組成調整は蓄冷時のみ行い、その他の運転時は行なわない。
組成調整の効果及びそのメカニズムについて説明する。
低沸点冷媒のＲ３２成分が多い混合冷媒を蒸発器である負荷側熱交換器９に流せば、圧力上昇、冷媒密度増大による冷媒流速の低減を図ることができるので、圧力損失を低減させて冷凍サイクルのＣＯＰを向上させることができる。
【０１０７】
そこで気液分離器１７を用いて組成調整を行う。気液分離器１７において、飽和ガスの組成はガス化しやすい低沸点のＲ３２が多くなっており、逆に飽和液の組成はガス化しにくい高沸点のＲ１３４ａが多くなっている。そこでＲ３２成分が多い飽和ガス冷媒を蒸発器である負荷側熱交換器９へ流通させるために、高低圧熱交換器１５で熱交換して液冷媒にした後減圧して負荷側熱交換器９入口へ流入させる。一方、Ｒ３２が少ない飽和液冷媒は、蒸発器である負荷側熱交換器９をバイパスさせて圧縮機１の吸入側へと戻すために減圧して低圧二相冷媒にした後、高低圧熱交換器１６で熱交換して低圧ガス冷媒として圧縮機１の吸入側へと流入する。
【０１０８】
以上により、実施の形態６で示した蓄熱式冷凍サイクルを使用すれば、圧縮機と、四方弁と、熱源側熱交換器と、組成調整装置としての高低圧熱交換器と気液分離器と、高低圧熱交換器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットで構成する冷媒回路において、蓄冷時に組成調整を行うことで吸入圧力を上昇させて、冷凍サイクルのＣＯＰを向上させることができる。
【０１０９】
【発明の効果】
この発明に係る蓄熱式冷凍サイクルは、複数の圧縮機と、四方弁と、熱源側熱交換器と、複数の気液分離器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、状況に応じ、複数の圧縮機を用いて多段圧縮運転と単段圧縮運転とを選択して実行することで、低設備コストでＣＯＰ向上による運転コストの低減を実現する効果が得られる。
【０１１０】
また、複数の圧縮機と、四方弁と、熱源側熱交換器と、複数の中間冷却器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、有する負荷ユニットと、を備え、状況に応じ、複数の圧縮機を用いて多段圧縮運転と単段圧縮運転とを選択して実行することで、低設備コストでＣＯＰ向上による運転コストの低減を実現する効果が得られる。
【０１１１】
また、複数の圧縮機と、四方弁と、熱源側熱交換器と、エコノマイザと、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、状況に応じ、複数の圧縮機を用いて多段圧縮運転と単段圧縮運転とを選択して実行することで、低設備コストでＣＯＰ向上による運転コストの低減を実現する効果が得られる。
【０１１２】
また、多段圧縮運転する場合は使用する複数の圧縮機を直列に接続し、単段圧縮運転する場合は使用する複数の圧縮機を並列に接続して、状況に応じ圧縮方法を選択することで、設備コスト、運転コストの低減を実現する効果が得られる。
【０１１３】
また、多段圧縮運転する場合に使用する各圧縮機の容量は、蓄冷時に多段圧縮運転する場合の各圧縮機の流量比に基づいて設定することで、蓄冷時のＣＯＰを向上する効果が得られる。
【０１１４】
また、所定の圧縮機は容量可変形の圧縮機であり、残りは容量一定形の圧縮機とすることで、設備コストが低減する効果が得られる。
【０１１５】
この発明に係る蓄熱式冷凍サイクルの運転方法は、蓄冷時は多段圧縮運転、蓄冷時以外の時は単段圧縮運転することで、蓄冷時のＣＯＰを向上する効果が得られる。
【０１１６】
また、複数の圧縮機の中で一番高い圧力となる圧縮機の吐出冷媒圧力と、一番低い圧力となる圧縮機の吸入冷媒圧力を検出し、前記吐出冷媒圧力と前記吸入冷媒圧力の比である圧縮比が予め定めた所定値より小さい場合は、単段圧縮運転を選択し、圧縮比が前記所定値より大きい場合は、多段圧縮運転を選択して、多段圧縮と単段圧縮という２つの圧縮方法において、現行運転と異なる圧縮方法を選択した場合、予め定めた制御時間経過後に圧縮方法を変更し、その後、予め定めた保護制御時間中は圧縮方法の変更を認めない運転方法により、低設備コストで低運転コストを実現する効果が得られる。
【０１１７】
この発明に係る蓄熱式冷凍サイクルは、圧縮機と、四方弁と、熱源側熱交換器と、膨張動力回収装置と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、蓄冷時に膨張動力回収装置を使用することで、蓄冷時のＣＯＰを向上する効果が得られる。
【０１１８】
また、圧縮機と、四方弁と、熱源側熱交換器と、高低圧熱交換器と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、蓄冷時に高低圧熱交換器を使用することで、蓄冷時のＣＯＰを向上する効果が得られる。
【０１１９】
また、圧縮機と、四方弁と、熱源側熱交換器と、組成調整装置と、複数の減圧装置と、それらを接続する配管と、を有する熱源ユニットと、蓄熱槽と、蓄熱槽内伝熱管と、それらを接続する配管と、蓄冷媒体と、を有する蓄熱ユニットと、負荷側熱交換器と、減圧装置と、それらを接続する配管と、を有する負荷ユニットと、を備え、冷媒が非共沸の混合冷媒の場合、蓄冷時に組成調整装置を用いて組成調整を行うことで、蓄冷時のＣＯＰを向上する効果が得られる。
【図面の簡単な説明】
【図１】実施の形態１を示す図で、蓄熱システムの冷凍サイクルの回路図である。
【図２】実施の形態１を示す図で、単段圧縮運転のＰ−ｈ線図である。
【図３】実施の形態１を示す図で、多段圧縮運転のＰ−ｈ線図である。
【図４】実施の形態１を示す図で、圧縮比と多段圧縮ＣＯＰと単段圧縮ＣＯＰの比を示した図である。
【図５】実施の形態２を示す図で、蓄熱システムの冷凍サイクルの回路図である。
【図６】実施の形態３を示す図で、蓄熱システムの冷凍サイクルの回路図である。
【図７】実施の形態４を示す図で、蓄熱システムの冷凍サイクルの回路図である。
【図８】実施の形態４を示す図で、蓄熱システムの冷凍サイクルの別の回路図である。
【図９】実施の形態４を示す図で、エジェクタ概略図である。
【図１０】実施の形態４を示す図で、Ｐ−ｈ線図である。
【図１１】実施の形態５を示す図で、蓄熱システムの冷凍サイクルの回路図である。
【図１２】実施の形態５を示す図で、蒸発器入口、出口、高低差熱交換器出口の比エンタルピを示す図である。
【図１３】実施の形態６を示す図で、蓄熱システムの冷凍サイクルの回路図である。
【図１４】従来の蓄熱システムの冷媒回路図である。
【符号の説明】
１，１ａ，１ｂ圧縮機、２四方弁、３熱源側熱交換器、４ａ気液分離器、４ｂ中間冷却器、４ｃエコノマイザ、５ａ，５ｃ，５ｄ減圧装置、６蓄熱槽、７蓄熱槽伝熱管、８蓄冷媒体、９負荷側熱交換器、１０ａ〜１０ｋ開閉弁、１１アキュムレータ、１２気液分離器、１３エジェクタ、１５高低圧熱交換器、１７気液分離器、１８エジェクタ吸入部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat storage refrigeration cycle and an operation method thereof.
[0002]
[Prior art]
FIG. 14 is an apparatus diagram of a conventional multistage compression operation method of a heat storage system disclosed in, for example, Japanese Patent Laid-Open No. 8-61795.
[0003]
In FIG. 14, 20 is a low pressure side compressor, 21 is a high pressure side compressor, 22 is a condenser, 23 is an intercooler, 24, 28 and 32 are expansion valves, 25 is an evaporator, and 27, 31 and 35 are switching. A valve, 30 is a 2nd condenser, 33 is a cool storage material cooler, 36 is a cool storage material, 39 is a cool storage pump, 40, 41, 42 is a thermal cylinder.
[0004]
Next, the operation will be described with reference to FIG.
When the load is low, such as at night, the refrigerant cooled by the condenser 22 is sent to the intercooler 23 as shown by the solid line arrow in FIG. Then, the refrigerant is depressurized by the expansion valve 28 and sent into the intermediate cooler 23 as a cooling medium for the intermediate cooler 23 to cool the refrigerant. And the refrigerant | coolant used for cooling in the intercooler 23 joins with the refrigerant | coolant of the high voltage | pressure side compressor 21, and cools this.
[0005]
On the other hand, a part of the refrigerant cooled in the intermediate cooler 23 is sent from the switching valve 35 opened by an opening corresponding to the refrigeration load to the evaporator 25 via the expansion valve 24, and is vaporized here. Freeze. In parallel with this, most of the refrigerant is sent from the switching valve 31 that is almost fully opened to the cool storage material pipe 34, and is decompressed by the expansion valve 32 to cool the internal cool storage material 36 in the cool storage material cooler 33.
[0006]
Next, at the time of normal load operation such as daytime, as shown by a dotted line arrow in the drawing, the switching valve 31 is closed and the regenerator pump 39 is driven to store the regenerator material of the regenerator cooler 33 stored at nighttime. 36 is supplied to the second condenser 30. As a result, the refrigerant sent from the condenser 22 is further cooled in the second condenser 30 and sent from the expansion valve 24 to the evaporator 25 via the switching valve 35 which is almost fully opened, where it is vaporized. Refrigerate for normal loads such as daytime.
[0007]
According to the multistage refrigeration apparatus and the multistage refrigeration method configured as described above, the cool storage material 36 is cooled by a part or almost all of the refrigerant that has passed through the intercooler 23 at low load, and the cold storage material 36 is stored at normal load operation. Refrigerant supplied to the evaporator 25 by reducing the flow rate of the cooling refrigerant to the intermediate cooler 23 by supplying the stored cool storage material 36 to the second condenser 30 and cooling the refrigerant at the outlet of the condenser 22. Since the flow rate of the refrigerant substantially contributing to refrigeration in the evaporator 25 can be significantly increased during normal load operation, the power consumption during normal load operation can be greatly reduced. In addition, it is possible to achieve leveling of power consumption during daytime and nighttime and reduction of power consumption.
[0008]
[Problems to be solved by the invention]
The conventional multistage compression operation method of the heat storage system is premised on a refrigeration apparatus having an evaporation temperature of −30 ° C. or less, and performing the multistage compression operation at all times is good in terms of performance and reliability of the compressor. However, assuming an evaporation temperature of 0 ° C. to 10 ° C., for example, during air conditioning, the compression ratio, which is the ratio between the refrigerant pressure on the discharge side of the compressor and the refrigerant pressure on the suction side, is smaller than that of the refrigeration apparatus, and thus the multistage compression operation Compared with the single-stage compression operation, the COP in actual operation is improved, and the compressor reliability may be hardly changed.
[0009]
Moreover, the refrigerating capacity at the time of the multistage compression operation is about half that of the single stage compression operation. For example, when two compressors are installed in a 10HP outdoor unit, two 10HP compressors must be prepared for two-stage compression operation, but two 5HP compressors must be prepared for single-stage compression operation. What is necessary is that constant multistage compression operation leads to an increase in equipment costs.
[0010]
This invention was made to eliminate such problems, and in the heat storage refrigeration cycle, while ensuring performance and reliability when the compression ratio is large, and assuming that the compression ratio is small, An object of the present invention is to provide a high-performance regenerative refrigeration cycle and its operation method at a low equipment cost.
[0011]
[Means for Solving the Problems]
A heat storage type refrigeration cycle according to the present invention includes a plurality of compressors, a four-way valve, a heat source side heat exchanger, a plurality of gas-liquid separators, a plurality of decompression devices, and a pipe connecting them. A heat storage unit having a heat source unit, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, a refrigerant storage body, a load-side heat exchanger, a decompression device, a pipe connecting them, The multi-stage compression operation and the single-stage compression operation are selected and executed using a plurality of compressors depending on the situation.
[0012]
In addition, a heat source unit having a plurality of compressors, a four-way valve, a heat source side heat exchanger, a plurality of intermediate coolers, a plurality of pressure reducing devices, and a pipe connecting them, a heat storage tank, and a heat storage A heat storage unit having a heat transfer pipe in a tank, a pipe connecting them, and a refrigerant storage body, a load-side heat exchanger, a decompression device, a pipe connecting them, and a load unit having a situation Accordingly, a multi-stage compression operation and a single-stage compression operation are selected and executed using a plurality of compressors.
[0013]
Also, a heat source unit having a plurality of compressors, a four-way valve, a heat source side heat exchanger, an economizer, a plurality of pressure reducing devices, and a pipe connecting them, a heat storage tank, and a heat transfer pipe in the heat storage tank And a heat storage unit having a pipe connecting them, a refrigerant storage body, a load side heat exchanger, a decompression device, and a load unit having a pipe connecting them, and depending on the situation, A multi-stage compression operation and a single-stage compression operation are selected and executed using a plurality of compressors.
[0014]
Further, when a multistage compression operation is performed, a plurality of compressors to be used are connected in series, and when a single stage compression operation is performed, a plurality of compressors to be used are connected in parallel.
[0015]
Moreover, the capacity | capacitance of each compressor used when performing multistage compression operation is set based on the flow rate ratio of each compressor at the time of multistage compression operation at the time of cold storage.
[0016]
The predetermined compressor is a variable capacity compressor, and the rest is a constant capacity compressor.
[0017]
The operation method of the regenerative refrigerating cycle according to the present invention is a multi-stage compression operation during cold storage, and a single-stage compression operation at times other than cold storage.
[0018]
Further, among the plurality of compressors, the refrigerant pressure at the discharge portion of the compressor at the most downstream of the refrigerant flow and the refrigerant pressure at the suction portion of the compressor at the most upstream are detected, and the discharge refrigerant pressure and the suction refrigerant are detected. When the compression ratio, which is the pressure ratio, is smaller than a predetermined threshold, single-stage compression operation is selected, and when the compression ratio is larger than the predetermined value, multi-stage compression operation is selected, and a compression method different from the current operation is selected. If selected, the compression method is changed after the elapse of a predetermined control time, and thereafter the change of the compression method is not allowed during the predetermined protection control time.
[0019]
A heat storage refrigeration cycle according to the present invention includes a compressor, a four-way valve, a heat source side heat exchanger, an expansion power recovery device, a plurality of decompression devices, and a heat source unit having a pipe connecting them, Load unit having a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, and a heat storage unit, a heat storage unit, a load-side heat exchanger, a decompression device, and a pipe connecting them And using an expansion power recovery device during cold storage.
[0020]
Also, a heat source unit having a compressor, a four-way valve, a heat source side heat exchanger, a high and low pressure heat exchanger, a plurality of pressure reducing devices, and piping connecting them, a heat storage tank, and a heat storage tank A heat storage unit having a heat transfer pipe, a pipe connecting them, and a refrigerant storage body, a load side heat exchanger, a decompression device, and a load unit having a pipe connecting them, and during cold storage A high-low pressure heat exchanger is used.
[0021]
Further, a heat source unit having a compressor, a four-way valve, a heat source side heat exchanger, a composition adjusting device, a plurality of pressure reducing devices, and a pipe connecting them, a heat storage tank, and a heat transfer tube in the heat storage tank And a load storage unit having a heat storage unit having a refrigerant storage body, a load-side heat exchanger, a decompression device, and a pipe connecting them. In the case of a boiling refrigerant mixture, the composition is adjusted using a composition adjusting device during cold storage.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
1 to 4 are diagrams showing Embodiment 1, FIG. 1 is a circuit diagram of a refrigeration cycle of a heat storage system, FIG. 2 is a Ph diagram of single-stage compression operation, and FIG. 3 is Ph of multi-stage compression operation. FIG. 4 is a diagram showing the compression ratio and the COP ratio on the theoretical refrigeration cycle of multistage compression and single stage compression.
In FIG. 1, 1a and 1b are compressors, 2 is a four-way valve, 3 is a heat source side heat exchanger (including a blower fan), 4a is a gas-liquid separator, 5a, 5c and 5d are decompression devices, and 6 is a heat storage tank. , 7 is a heat storage tank heat transfer tube, 8 is a refrigerant storage body, 9 is a load side heat exchanger (including a blower fan), 10a to 10k are open / close valves, 11 is an accumulator, X is a heat source unit, Y is a load unit, and Z is In the heat storage unit, the heat source unit X, the load unit Y, and the heat storage unit Z constitute a refrigeration cycle.
[0023]
When performing single-stage compression, the on-off valves 10a and 10b are opened, the on-off valve 10c is closed, the suction sides of the compressors 1a and 1b are communicated via the on-off valve 10a, and the discharge sides of the compressors 1a and 1b. Communicates via the on-off valve 10b. This circuit configuration is called a parallel connection configuration. On the other hand, when performing two-stage compression, the on-off valves 10a and 10b are closed, the on-off valve 10c is opened, and the discharge side of the compressor 1a communicates with the suction side of the compressor 1b via the on-off valve 10c. This compressor circuit configuration is referred to as a series connection configuration.
[0024]
Next, operations of single-stage compression operation and two-stage compression operation during cold storage will be described with reference to FIG. During cold storage, the on-off valve 10h is opened, the on-off valves 10j, 10k, 10i are closed, and the heat source unit X and the heat storage unit Z constitute a refrigeration cycle.
[0025]
The operation of the single stage compression operation during cold storage will be described.
The on-off valves 10a, 10b, and 10g are opened, the on-off valves 10c, 10d, and 10f are closed, and the decompression device 5a is fully closed.
[0026]
Then, the high-pressure gas refrigerant compressed and discharged by the compressor 1a merges with the high-pressure gas refrigerant compressed and discharged by the compressor 1b via the on-off valve 10b, and the heat source side heat via the four-way valve 2. It flows into the exchanger 3. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant Then, the pressure is reduced by the pressure reducing device 5c through the on-off valve 10g to be in a low pressure two-phase state and flows into the heat storage tank heat transfer tube 7. The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1a via the accumulator 11, and flows into the suction side of the compressor 1b via the on-off valve 10a. On the other hand, in the heat storage tank 6, the temperature of the refrigerant storage body 8 decreases due to the endothermic action of the refrigerant flowing through the heat storage tank heat transfer tube 7, and when the temperature reaches the solidification temperature, it begins to solidify around the heat storage tank heat transfer tube 7.
[0027]
The operation of the two-stage compression operation during cold storage will be described.
The on-off valves 10c, 10d, and 10f are opened, and the on-off valves 10a, 10b, and 10g are closed.
[0028]
The gas refrigerant compressed and discharged by the compressor 1a passes through the on-off valve 10c, and then the medium-pressure saturated gas refrigerant flowing from the gas-liquid separator 4a joins through the on-off valve 10d, and the compressor 1b Into the inhalation side. The high-pressure gas refrigerant compressed and discharged by the compressor 1 b flows into the heat source side heat exchanger 3 through the four-way valve 2. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant After being depressurized by the decompression device 5a, it becomes an intermediate pressure two-phase refrigerant and flows into the gas-liquid separator 4a.
[0029]
The medium-pressure saturated gas refrigerant separated by the gas-liquid separator 4a flows into the suction side of the compressor 1b through the on-off valve 10d, while the medium-pressure saturated liquid refrigerant is decompressed by the decompression device 5c through the on-off valve 10f. After that, it enters a low pressure two-phase state and flows into the heat storage tank heat transfer tube 7. The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1a through the accumulator 11. On the other hand, in the heat storage tank 6, the temperature of the refrigerant storage body 8 decreases due to the endothermic action of the refrigerant flowing through the heat storage tank heat transfer tube 7, and when the temperature reaches the solidification temperature, it begins to solidify around the heat storage tank heat transfer tube 7.
[0030]
The operation of the single-stage compression operation at the time of cooling using the cold storage will be described. During the regenerative cooling operation, the on-off valves 10i, 10j, and 10k are opened, the on-off valve 10h is closed, and the heat source unit X, the load unit Y, and the heat storage unit Z constitute a refrigeration cycle.
[0031]
The on-off valves 10a, 10b, and 10g are opened, the on-off valves 10c, 10d, and 10f are closed, and the decompression device 5a is fully closed.
[0032]
Then, the high-pressure gas refrigerant compressed and discharged by the compressor 1a merges with the high-pressure gas refrigerant compressed and discharged by the compressor 1b via the on-off valve 10b, and the heat source side heat via the four-way valve 2. It flows into the exchanger 3. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant It flows out and flows through the decompression device 5c through the on-off valve 10g, but here flows into the heat storage tank heat transfer pipe 7 without being decompressed.
[0033]
The heat storage tank heat transfer pipe 7 is condensed by heat exchange with the refrigerant storage body 8 having a temperature lower than the refrigerant temperature circulating in the pipe, and flows out as a supercooled high-pressure liquid refrigerant at the outlet of the heat storage tank heat transfer pipe 7. It flows through the on-off valve 10k to the decompression device 5d, where it is decompressed and flows into the load-side heat exchanger 9 in a low-pressure two-phase refrigerant state. In the load side heat exchanger 9, it is evaporated by heat exchange with ambient air having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low pressure gas refrigerant at the outlet of the load side heat exchanger 9, and the four-way valve 2 and the accumulator 11. And flows into the suction side of the compressor 1a, and flows into the suction side of the compressor 1b through the on-off valve 10a.
[0034]
The capacities of the compressors 1a and 1b used for the two-stage compression are determined on the assumption of the two-stage compression operation at the time of cold storage.
The target refrigerant is a mixed refrigerant R407C, and for the sake of simplicity, the composition is R32: R125: R134a = 23%: 25%: 52% constant, the condenser outlet is in a saturated liquid state, and the evaporator outlet is It is assumed that the gas is saturated and the pressure loss is not in any place other than the decompression device. The compression is adiabatic compression and the expansion is isentropic change.
[0035]
Next, as calculation conditions, the high pressure in the refrigeration cycle during cold storage is set to 1.6 [MPa], the low pressure is set to 0.4 [MPa], and the intermediate pressure is assumed to be a constant compression ratio on the high stage side and a compression ratio on the low stage side. And 0.8 [MPa]. In addition, RefProp Ver. 6 is used.
[0036]
The calculation results of single-stage compression and two-stage compression under the above conditions are shown in the Ph diagrams of FIGS.
Specific enthalpy difference Δhe1 = 152.4 [kJ / kg] between the inlet and outlet of the evaporator in FIG.
Specific enthalpy difference Δhe2 = 191.1 [kJ / kg] between the inlet and outlet of the evaporator in FIG.
Gas-liquid separation ratio in FIG. 3 = Δhg: Δhl = 19.3%: 80.7%
In order to ensure the same refrigeration capacity as in the single-stage compression operation even in the two-stage compression operation, the capacity of the lower-stage compressor can be obtained by the equation Δhe1 / Δhe2 with respect to the capacity 1 of the single-stage compressor. The calculation is 0.797. On the other hand, the capacity of the upper compressor can be obtained using the lower compressor capacity and the gas-liquid separation ratio. When calculated, the capacity of the upper stage compressor is 0.988. After that, in consideration of the load upper limit value of the refrigeration cycle, the proportional design is performed while maintaining the upper and lower compressor capacity ratios.
[0037]
The compressor capacity may be adjusted by the volume of the stroke volume in the compressor, or may be adjusted by the rotation speed of the compressor by installing an inverter. In this case, if one compressor is operated with a variable operating capacity equipped with an inverter and the other compressor is operated with a constant operating capacity, the inverter can be reduced by one and the equipment cost can be reduced. Connected.
[0038]
Also, when the refrigerant type other than R407C is used, the operation method of the single-stage compression operation and the two-stage compression operation is the same.
[0039]
The advantages of two-stage compression and single-stage compression are shown.
The advantage of two-stage compression is that COP is good and the compression ratio per unit is small, so the force applied to the bearings is small, so the reliability of the compressor is high. This feature becomes remarkable. An example is shown below.
2 and 3, the COP on the theoretical refrigeration cycle under the same refrigeration capacity in the two-stage compression and the single-stage compression is calculated. COP = refrigeration capacity [kJ / h] / compressor input [kJ / h]
When the refrigerant flow rate G = 1 [kg / h] in the case of single-stage compression,
・ Refrigeration capacity Qr = G × Δhe1 = 152.4 [kJ / h]
Compressor input W = G × Δhw1 = 34.0 [kJ / h]
COP = Qr / W = 4.48
It becomes.
[0040]
On the other hand, in the case of multi-stage compression, the refrigerant flow rate for ensuring the same refrigeration capacity as in single-stage compression is G lower stage = 0.797 [kg / h] and G upper stage = 0.988 [kg / h].
・ Compressor upper stage input W upper stage = G upper stage × Δhw2 = 16.3 [kJ / kg]
・ Compressor lower stage input W lower stage = G lower stage × Δhw3 = 13.5 [kJ / kg]
COP = Qr / (W upper stage + W lower stage) = 5.11
Thus, it is improved by about 14% compared with the COP of the single stage compression.
[0041]
In addition, if the compression ratio is large, the compressor discharge gas refrigerant temperature rises, the deterioration of the refrigeration oil is accelerated, the compressor may break down or the refrigerant may be thermally decomposed, and the reliability of the compressor is increased. descend. Reducing the compression ratio by two-stage compression leads to improved reliability.
[0042]
On the other hand, the advantage of single-stage compression is that the refrigeration capacity is large. An example is shown below.
2 and 3, assuming that the capacity of the two compressors is 0.797 and 0.988, the refrigeration capacity when performing single-stage compression and two-stage compression is
-Refrigerating capacity Qr = (0.797 + 0.988) for single-stage compression- Δhe1 = 272.0 [kJ / h]
-Two-stage compression refrigeration capacity Qr = 0.988 · Δhe2 = 152.4 [kJ / h]
Thus, at the time of single-stage compression, it is possible to increase the capacity by 179% compared with the case of two-stage compression.
The total refrigeration capacity when single-stage compression is performed using two compressors with the same capacity can be expressed as the capacity of each compressor x number of units, but the total refrigeration capacity when compressed in two stages is about one unit of compression. The capacity is reduced and the refrigeration capacity is approximately half that of single-stage compression. For example, when two compressors for 5HP are installed in an outdoor unit rated at 10 HP, 10HP can be secured as the total refrigeration capacity when the two compressors are operated in a single stage compression. As a total refrigeration capacity, 10 HP capacity cannot be secured at about 5 HP.
[0043]
Further, when the compression ratio is small, the difference in COP on the theoretical refrigeration cycle between the two-stage compression and the single-stage compression becomes small. FIG. 4 shows the relationship between the compression ratio when the low pressure is constant at 0.4 [MPa] and the improvement ratio of COP to the single-stage compression of the two-stage compression on the theoretical refrigeration cycle. When the compression ratio is reduced, in consideration of the pressure loss in the actual cycle, the heat loss in the gas-liquid separator, the heat loss of the compressor inverter, the characteristics of the compressor alone, etc., single-stage compression as shown in Fig. 4 There are operating conditions in which the COP improves.
[0044]
Next, the required compressor capacity during the cold storage operation will be described. In daytime cold storage cooling operation, the ratio of using cold storage heat is about 20% to 40% of the total load during the day, and the rest is generally covered by driving a compressor. Suppose that the total load during the day is rated cooling capacity x operating time. Further, assuming that the cooling time during the daytime and the cold storage time during the night are the same, the refrigeration capacity required during cold storage is 20% to 40% during rated cooling. In addition, considering the difference in evaporation temperature during cooling and storage and the difference in ambient air temperature of the heat source side heat exchanger 3, that is, the difference in ambient temperature between daytime and nighttime, the compressor capacity required for cold storage is Less than half.
[0045]
Considering that the required compressor capacity is more than twice as much during daytime cold storage cooling and during cold storage, the required refrigeration capacity is large and the compression ratio is small during cold storage cooling. Performs single-stage compression operation with an emphasis on securing, and since the required refrigeration capacity is low at the time of cold storage and the evaporation temperature is low, the compression ratio tends to increase, so COP is good and the reliability of the compressor is high If the compression operation is performed, a system with a low equipment cost and a low operation cost can be realized.
[0046]
In addition, when the required refrigeration capacity amount such as cold storage is small and the compression ratio becomes small and the COP of the single-stage compression operation becomes better than the COP of the two-stage compression operation on the actual refrigeration cycle, one unit from the two-stage compression operation If single stage operation is used, high COP operation can be realized at low cost.
[0047]
When the two-stage compression operation is always performed, for example, it is necessary to install two 10HP compressors in a model having a rated 10HP, which increases the equipment cost. If the evaporation temperature is -30 ° C, for example, if it is not a refrigeration device and the device assumes an evaporation temperature of -10 ° C or higher, the single-stage compression operation and the two-stage compression operation can be switched and 5HP compression is performed. Installation of two machines is more effective in terms of equipment costs.
[0048]
From the above, switching operation in consideration of the advantages of two-stage compression and single-stage compression is very effective in reducing equipment costs and operation costs due to COP improvement.
[0049]
As an example of the operation switching method between the two-stage compression and the single-stage compression, the single-stage compression operation is performed during the daytime cooling operation, and the multistage compression operation is performed during the cold storage at night.
[0050]
As another example of the operation switching method between the two-stage compression and the single-stage compression, the pressure on the discharge side of the compressor having the highest pressure and the pressure on the suction side of the compressor having the lowest pressure are detected by some means. When the compression ratio exceeds a predetermined threshold, two-stage compression is selected, and when the compression ratio does not exceed the threshold, single-stage compression is selected.
[0051]
As another example of the operation switching method between the two-stage compression and the single-stage compression, the condensation temperature of the condenser and the evaporation temperature of the evaporator are detected by some method, and the high pressure and low pressure are calculated from these values, and the pressure ratio If the value exceeds a predetermined threshold, two-stage compression is selected, and if the threshold is not exceeded, single-stage compression is selected.
[0052]
The threshold defines the point where the superiority of single-stage compression and two-stage compression is reversed due to the relationship between the compression ratio and COP. The COP is not a theoretical COP on the theoretical refrigeration cycle, but an actual COP that considers pressure loss and heat loss on the actual cycle and performance characteristics of the compressor alone. It goes without saying that it is better if the threshold value can be confirmed not only by calculation but also by actual machine tests.
[0053]
As one means for detecting the refrigerant pressure, there is an example in which a pressure sensor is provided in the suction pipe of the compressor 1a and a pressure sensor is provided in the discharge pipe of the compressor 1c to detect each pressure. In addition, there is cold for detecting a condensation temperature and an evaporation temperature by providing a temperature sensor in each of the two-phase refrigerant circulation portions of the heat source side heat exchanger 3 and the load side heat exchanger 9.
[0054]
During operation, the compression ratio or pressure ratio is obtained by detecting the discharge pressure and suction pressure of the refrigeration cycle or the high and low pressures calculated from the condensation temperature and evaporation temperature at predetermined detection times, and compared with the threshold value. Judge whether it is large or small and select either single-stage compression or two-stage compression. If it is necessary to change the current compression method, it is changed.
[0055]
The detection time interval is set in consideration of the time until the refrigeration cycle is stabilized after the actuator is changed. However, since the detection time interval varies greatly depending on the scale of the refrigeration cycle and the length of the extended pipe, the time most suitable for each condition is found and set.
In addition, excessive changes in the compression method may damage the compressor due to pressure changes and shorten the service life, so it is determined that the compression method will not be changed for a certain interval after changing the compression method, It is also effective in terms of reliability of the refrigeration cycle to limit the number of changes in the compression method from one start to stop.
[0056]
The switching between the multi-stage compression operation and the single-stage compression operation can be applied at the time of heat storage and heating operation using the heat storage. The description is omitted here.
[0057]
Since the heat storage tank of the heat storage unit can be applied as long as it is a conventional ice-on-coil static ice heat storage tank, it is possible to construct a refrigerant circuit using the conventional heat storage tank at the time of renewal.
[0058]
As described above, if the heat storage refrigeration cycle shown in the first embodiment is used, a plurality of compressors, a four-way valve, a heat source side heat exchanger, a plurality of gas-liquid separators, a plurality of decompression devices, A heat source unit having a pipe connecting them, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, a heat storage unit having a refrigerant body, a load-side heat exchanger, and a pressure reducing device And a refrigerant circuit composed of a load unit having them and detecting a required refrigeration capacity and compression ratio, and performing a single-stage compression operation or a multi-stage compression operation with a plurality of compressors By adopting a circuit configuration and an operation method that can select the above, it is possible to reduce the equipment cost and the operation cost by improving the COP.
[0059]
Embodiment 2. FIG.
Embodiment 2 of the present invention will be described below with reference to the drawings.
FIG. 5 is a diagram showing the second embodiment and is a circuit diagram of a refrigeration cycle of the heat storage system. In FIG. 5, 1a and 1b are compressors, 2 is a four-way valve, 3 is a heat source side heat exchanger (including a fan), 4b is an intercooler, 5a, 5c and 5d are decompressors, 6 is a heat storage tank, 7 is a heat storage tank heat transfer tube, 8 is a refrigerant storage body, 9 is a load side heat exchanger (including a blower fan), 10a to 10k are open / close valves, 11 is an accumulator, X is a heat source unit, Y is a load unit, and Z is a heat storage. In the unit, the heat source unit X, the load unit Y, and the heat storage unit Z constitute a refrigeration cycle.
[0060]
Next, operations of single-stage compression operation and two-stage compression operation during cold storage will be described with reference to FIG.
During cold storage, the on-off valve 10h is opened, the on-off valves 10i, 10j, and 10k are closed, and the heat source unit X and the heat storage unit Z constitute a refrigeration cycle.
[0061]
The operation of the single stage compression operation during cold storage will be described.
The on-off valves 10a, 10b, and 10f are opened, the on-off valves 10c, 10d, and 10g are closed, and the decompression device 5a is fully closed.
[0062]
Then, the high-pressure gas refrigerant compressed and discharged by the compressor 1a merges with the high-pressure gas refrigerant compressed and discharged by the compressor 1b via the on-off valve 10b, and the heat source side heat via the four-way valve 2. It flows into the exchanger 3. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant and a high-pressure two-phase refrigerant Although it flows out and flows into the intercooler 4b, heat is not exchanged here, and the pressure is reduced by the pressure reducing device 5c via the on-off valve 10f and flows into the heat storage tank heat transfer tube 7. The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1a via the accumulator 11, and flows into the suction side of the compressor 1b via the on-off valve 10a. Since the phenomenon occurring in the heat storage tank 6 is the same as that in the cold storage of the first embodiment, the description thereof is omitted.
[0063]
The operation of the two-stage compression operation during cold storage will be described.
The on-off valves 10c, 10d, and 10f are opened, and the on-off valves 10a, 10b, and 10g are closed.
[0064]
The gas refrigerant compressed and discharged by the compressor 1a passes through the on-off valve 10c, and then the intermediate-pressure gas refrigerant or intermediate-pressure two-phase refrigerant flowing from the intermediate cooler 4b joins through the on-off valve 10d. And flows into the suction side of the compressor 1b. The high-pressure gas refrigerant compressed and discharged by the compressor 1 b flows into the heat source side heat exchanger 3 through the four-way valve 2. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant It flows out, branches in the middle, one flows as it is into the heat transfer pipe in the intermediate heat exchanger 4b, and the other is decompressed by the decompression device 5a, and then becomes an intermediate pressure two-phase refrigerant and flows into the intermediate cooler 4b. To do.
[0065]
Since the intermediate-pressure refrigerant temperature in the intermediate cooler 4b is lower than the refrigerant temperature of the high-pressure liquid refrigerant or high-pressure two-phase refrigerant flowing into the heat transfer pipe in the intermediate cooler 4b, the high-pressure liquid refrigerant or high-pressure two-phase refrigerant is Here, after further condensing and flowing out as a high-pressure liquid refrigerant, the pressure is reduced by the pressure reducing device 5c via the on-off valve 10f and flows into the heat storage tank heat transfer tube 7.
[0066]
On the other hand, the intermediate-pressure two-phase refrigerant flowing into the container of the intermediate cooler 4b evaporates to become an intermediate-pressure gas refrigerant or an intermediate-pressure two-phase refrigerant, and merges with the discharge gas refrigerant of the compressor 1a via the on-off valve 10d. Then, it flows into the suction side of the compressor 1b.
[0067]
The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1a through the accumulator 11. Since the phenomenon occurring in the heat storage tank 6 is the same as that in the cold storage of the first embodiment, the description thereof is omitted.
[0068]
Although the capacity | capacitance of the compressor used for two-stage compression is determined supposing cold storage operation, since the procedure of the specific determination method is the same as that of Embodiment 1, description is abbreviate | omitted.
[0069]
Also, when the refrigerant type other than R407C is used, the operation method of the single-stage compression operation and the two-stage compression operation is the same.
[0070]
Since it has been described in the first embodiment that the equipment cost of the refrigeration cycle can be reduced by performing the switching operation between the two-stage compression and the single-stage compression, and the operation cost by improving the COP has been described, it is omitted here, and the compression method is switched. Since the method is the same as that of the first embodiment, the description thereof is omitted.
[0071]
As described above, if the heat storage refrigeration cycle shown in the second embodiment is used, a plurality of compressors, a four-way valve, a heat source side heat exchanger, a plurality of intermediate coolers, a plurality of decompression devices, and A heat source unit, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, a heat storage unit having a refrigerant storage body, a load-side heat exchanger, and a pressure reducing device. In a refrigerant circuit composed of a load unit having a pipe connecting them, whether a single-stage compression operation or a multi-stage compression operation is performed with a plurality of compressors by detecting the required refrigeration capacity and compression ratio. By adopting a circuit configuration and an operation method that can be selected, it is possible to reduce the equipment cost and the operation cost by improving the COP.
[0072]
Embodiment 3 FIG.
Embodiment 3 of the present invention will be described below with reference to the drawings.
FIG. 6 is a diagram showing the third embodiment and is a circuit diagram of a refrigeration cycle of the heat storage system. In FIG. 6, 1a and 1b are compressors, 2 is a four-way valve, 3 is a heat source side heat exchanger (including a fan), 4c is an economizer, 5c and 5d are decompressors, 6 is a heat storage tank, and 7 is a heat storage tank. Heat transfer tubes, 8 is a refrigerant storage unit, 9 is a load side heat exchanger (including a fan), 10a to 10k are on-off valves, 11 is an accumulator, X is a heat source unit, Y is a load unit, Z is a heat storage unit, Unit X, load unit Y, and heat storage unit Z constitute a refrigeration cycle.
[0073]
Next, operations of single-stage compression operation and two-stage compression operation during cold storage will be described with reference to FIG. During cold storage, the on-off valve 10h is opened, the on-off valves 10i, 10j, and 10k are closed, and the heat source unit X and the heat storage unit Z constitute a refrigeration cycle.
[0074]
The operation of the single stage compression operation during cold storage will be described.
The on-off valves 10a, 10b, and 10g are opened, and the on-off valves 10c, 10d, 10e, and 10f are closed.
[0075]
Then, the high-pressure gas refrigerant compressed and discharged by the compressor 1a merges with the high-pressure gas refrigerant compressed and discharged by the compressor 1b via the on-off valve 10b, and the heat source side heat via the four-way valve 2. It flows into the exchanger 3. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant Then, the pressure is reduced by the pressure reducing device 5c through the on-off valve 10g and flows into the heat storage tank heat transfer tube 7. The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1a via the accumulator 11, and flows into the suction side of the compressor 1b via the on-off valve 10a. Since the phenomenon occurring in the heat storage tank 6 is the same as that in the cold storage of the first embodiment, the description thereof is omitted.
[0076]
The operation of the two-stage compression operation during cold storage will be described.
The on-off valves 10c, 10d, 10e, and 10f are opened, and the on-off valves 10a, 10b, and 10g are closed. At this time, the discharge side of the compressor 1a communicates with the suction side of the compressor 1b via the on-off valve 10c.
[0077]
The gas refrigerant compressed and discharged by the compressor 1a passes through the on-off valve 10c, and then the medium-pressure saturated gas refrigerant flowing in from the economizer 4c joins through the on-off valve 10d, so that the suction side of the compressor 1b Flow into. The high-pressure gas refrigerant compressed and discharged by the compressor 1 b flows into the heat source side heat exchanger 3 through the four-way valve 2. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant The medium pressure saturated gas refrigerant that has been gas-liquid separated after depressurization after flowing into the economizer 4c through the on-off valve 10e flows into the suction side of the compressor 1b through the on-off valve 10d, while remaining The pressure-saturated liquid refrigerant is further depressurized to become a low-pressure two-phase refrigerant and flows into the heat storage tank heat transfer tube 7 through the on-off valve 10f.
[0078]
The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1a through the accumulator 11. Since the phenomenon occurring in the heat storage tank 6 is the same as that in the cold storage of the first embodiment, the description thereof is omitted.
[0079]
Although the capacity | capacitance of the compressor used for two-stage compression is determined supposing cold storage operation, since the procedure of the specific determination method is the same as that of Embodiment 1, description is abbreviate | omitted.
[0080]
Also, when the refrigerant type other than R407C is used, the operation method of the single-stage compression operation and the two-stage compression operation is the same.
[0081]
Since it has been described in the first embodiment that the equipment cost of the refrigeration cycle can be reduced by performing the switching operation between the two-stage compression and the single-stage compression, and the operation cost by improving the COP has been described, it is omitted here, and the compression method is switched. Since the method is the same as that of the first embodiment, the description thereof is omitted.
[0082]
As described above, if the heat storage refrigeration cycle shown in the third embodiment is used, a plurality of compressors, a four-way valve, a heat source side heat exchanger, an economizer, a plurality of pressure reducing devices, and piping connecting them. A heat source unit, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, a heat storage unit, a heat storage unit, a load side heat exchanger, a decompression device, and connecting them In a refrigerant circuit composed of a load unit having a pipe to be operated, a circuit capable of detecting a required refrigeration capacity and a compression ratio and selecting a single-stage compression operation or a multi-stage compression operation with a plurality of compressors. By adopting the configuration and operation method, it is possible to reduce the facility cost and the operation cost by improving the COP.
[0083]
Embodiment 4 FIG.
Embodiment 4 of the present invention will be described below with reference to the drawings.
FIGS. 7 to 10 are diagrams showing a fourth embodiment, FIGS. 7 and 8 are schematic views of a refrigeration cycle of a heat storage system, FIG. 9 is a schematic diagram of an ejector, and FIG. 10 is a Ph diagram.
In FIG. 7, 1 is a compressor, 2 is a four-way valve, 3 is a heat source side heat exchanger (including a blower fan), 5c and 5d are decompressors, 6 is a heat storage tank, 7 is a heat storage tank heat transfer tube, and 8 is a cold storage. Medium, 9 is a load side heat exchanger (including a blower fan), 10a to 10k are on-off valves, 12 is a gas-liquid separator, 13 is an ejector, X is a heat source unit, Y is a load unit, Z is a heat storage unit, The heat source unit X, the load unit Y, and the heat storage unit Z constitute a refrigeration cycle.
[0084]
Next, the operation during cold storage will be described with reference to FIG.
During cold storage, the on-off valve 10f is opened, the on-off valves 10i, 10j, and 10k are closed, and the heat source unit X and the heat storage unit Z constitute a refrigeration cycle.
[0085]
The on-off valves 10b, 10d, and 10e are opened, and the on-off valves 10a and 10c are closed. The high-pressure gas refrigerant compressed and discharged by the compressor 1 flows into the heat source side heat exchanger 3 through the four-way valve 2. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant It flows out and flows into the ejector 13 through the on-off valve 10b. In the ejector 13, the low-pressure gas refrigerant flows from the suction portion into the low-pressure two-phase refrigerant decompressed by the entropy change at the nozzle portion of FIG. Inflow. The pressure change of this operation is shown in FIG.
[0086]
The gas-liquid separated medium pressure saturated gas refrigerant flows into the compressor 1 suction side through the on-off valve 10d, and the medium pressure saturated liquid refrigerant flows into the pressure reducing device 5c through the on-off valve 10e. Then, it flows into the heat storage tank heat transfer tube 7 in a low-pressure two-phase refrigerant state. In the heat storage tank heat transfer pipe 7, it is evaporated by heat exchange with the refrigerant storage body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7, and is ejected via the on-off valve 10f. It flows into the suction part 18. Since the phenomenon occurring in the heat storage tank 6 is the same as that in the cold storage of the first embodiment, the description thereof is omitted.
[0087]
Further, as shown in FIG. 8, when one end of the suction pipe having the on-off valve 10a is connected to the gas-liquid separator, it can be used as an accumulator except for the livestock cooling operation, and the equipment cost can be reduced. When the animal is cooled, the on-off valves 10b and 10l are opened and the on-off valve 10a is closed. In other than the cooling operation, the on-off valve 10a is opened and the on-off valves 10b, 10l are closed.
[0088]
The ejector 13 is used only during cold storage, and the ejector 13 and the gas-liquid separator 12 are not used during other operations.
The effect of the ejector 13 will be briefly described.
In the expansion process in which the high-pressure liquid refrigerant is converted into the low-pressure two-phase refrigerant, if decompression and expansion are performed by a conventional decompression device, expansion energy is discharged outside the refrigeration cycle due to a change in isoenthalpy. On the other hand, since the ejector 13 does not reduce the expansion energy due to adiabatic expansion, that is, isentropic change, the refrigeration capacity of the refrigeration cycle is improved.
[0089]
The ejector 13 is applied only during cold storage because the lower the evaporator temperature, the higher the recovery rate of expansion energy and the more effective.
The ejector 13 converts the adiabatic heat drop into kinetic energy at the nozzle, and performs a compression work to suck the suction flow from the ejector suction unit 18 and increase the suction pressure of the compressor 1. The ratio η between the driving flow energy and the suction flow compression work is defined as the ejector efficiency. For example, if the ejector efficiency is 0.5, the suction pressure is 9.80665 × 104 [Pa] higher than the refrigerant pressure in the heat storage tank heat transfer pipe when cold storage is performed using water as the cold storage material and the evaporation temperature is −10 ° C. It is theoretically possible to do. On the other hand, when the evaporation temperature is about 10 ° C., the suction pressure rises by less than half of that, so in the actual cycle, the ejector effect disappears due to the influence of other pressure losses.
[0090]
As described above, if the heat storage refrigeration cycle shown in the fourth embodiment is used, a compressor, a four-way valve, a heat source side heat exchanger, an ejector, a gas-liquid separator, a plurality of pressure reducing devices, A heat source unit having a pipe to be connected, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, and a heat storage unit, a heat source side unit having a refrigerant body, a load side heat exchanger, and a pressure reducing device. In a refrigerant circuit composed of a load-side unit having a pipe connecting them, by operating using an expansion power recovery device during cold storage, the cool energy storage operation COP is effectively utilized by utilizing the expansion energy that has been discarded in the past. Can be improved.
[0091]
Embodiment 5 FIG.
Embodiment 5 of the present invention will be described below with reference to the drawings.
11 and 12 are diagrams showing the fifth embodiment, FIG. 11 is a circuit diagram of a refrigeration cycle of the heat storage system, and FIG. 12 is a diagram showing specific enthalpies of the evaporator inlet, outlet, and elevation difference heat exchanger outlet.
In FIG. 11, 1 is a compressor, 2 is a four-way valve, 3 is a heat source side heat exchanger (including a blower fan), 5c and 5d are decompressors, 6 is a heat storage tank, 7 is a heat storage tank heat transfer tube, and 8 is a cold storage. Medium, 9 is a load side heat exchanger (including a blower fan), 10e to 10k are on-off valves, 11 is an accumulator, 15 is a high / low pressure heat exchanger, X is a heat source unit, Y is a load unit, Z is a heat storage unit The heat source unit X, the load unit Y, and the heat storage unit Z constitute a refrigeration cycle.
[0092]
Next, operation | movement of the refrigerant circuit incorporating the high-low pressure heat exchanger 15 at the time of cold storage is demonstrated using FIG.
At the time of cold storage, the on-off valves 10i, 10j, and 10k are closed, and the heat source unit X and the heat storage unit Z constitute a refrigeration cycle.
[0093]
The on-off valves 10e and 10f are opened. The high-pressure gas refrigerant compressed and discharged by the compressor 1 flows into the heat source side heat exchanger 3 through the four-way valve 2. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant flowing through the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant It flows out and flows into the high / low pressure heat exchanger 15. Here, heat is exchanged with the low-pressure refrigerant, and further condensed and subcooled as high-pressure liquid refrigerant, flows out through the on-off valve 10e, flows into the decompression device 5c, is decompressed here, and then is stored in the low-pressure two-phase refrigerant state. It flows into the heat transfer tube 7.
[0094]
In the heat storage tank heat transfer pipe 7, it is evaporated by heat exchange with the refrigerant storage body 8 having a temperature higher than the temperature of the refrigerant circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7 and flows through the on-off valve 10f. The refrigerant flows into the low-pressure heat exchanger 15 where it evaporates by exchanging heat with the high-pressure refrigerant, and flows into the suction side of the compressor 1 through the accumulator 11 as a low-pressure superheated gas. Since the phenomenon occurring in the heat storage tank 6 is the same as that in the cold storage of the first embodiment, the description thereof is omitted.
[0095]
The high / low pressure heat exchanger 15 is used only during cold storage, and is not used during other operations. Explain the reason for using it only for cold storage.
When the refrigerant temperature at the evaporator outlet is lower than the ambient air, the refrigerant dissipates heat to the ambient air in the course of the path leading to the suction side of the compressor 1, and the refrigerant becomes a superheated gas. When storing cold, the refrigerant temperature at the outlet of the evaporator is particularly low, and the amount of heat released to the surrounding air cannot be ignored. If the cold heat that has been discharged to the surroundings is recovered on the high-pressure liquid side of the refrigeration cycle, the refrigeration capacity of the refrigeration cycle increases.
[0096]
For example, the evaporator outlet temperature during cooling is 10 ° C., the evaporator outlet temperature during cold storage is −10 ° C., and both are in a saturated gas state, and the ambient air temperature is 25 ° C. The high-low pressure heat exchanger outlet temperature is set to ambient air temperature -5 [° C.], that is, 20 ° C.
[0097]
The target refrigerant is R407C, and the circulation composition is R32: R125: R134a = 23%: 25%: 52% which is an enclosed composition. The physical properties were calculated using RefpropVer. 6 is used.
The value of specific enthalpy at the evaporator inlet, outlet, and elevation difference heat exchanger outlet is shown in FIG.
[0098]
From FIG. 12, the heat exchange amount ratio η occupied by the height difference heat exchanger is calculated.
Cooling η = (hexex-heout) / (hexex-hein) = 4.1%
-Cold storage η = (hex-out) / (hex-out) = 12.4%
It becomes. Of the total amount of heat exchanged in the evaporator, the heat corresponding to the calculation result was previously thrown away into the ambient air, but if recovered on the high-pressure liquid side of the refrigeration cycle, the refrigeration capacity is increased by that amount. be able to.
It can be seen that the amount of recovered heat increases as the evaporation temperature is lower, and the effect of recovering the cold in the elevation difference heat exchanger is significantly more effective during cold storage than during cooling.
Moreover, when the heat storage tank heat transfer tube outlet is a low-pressure two-phase refrigerant, the amount of latent heat of the refrigerant and the amount of heat exchange are increased, and the cold energy recovery effect is further increased.
[0099]
On the other hand, on the high-pressure liquid refrigerant side from which the cold energy has been recovered, the degree of supercooling of the liquid refrigerant is increased by heat exchange, and as a result, the specific enthalpy difference between the evaporator inlet and outlet can be increased to improve the refrigerating capacity.
[0100]
As described above, if the heat storage refrigeration cycle shown in the fifth embodiment is used, a compressor, a four-way valve, a heat source side heat exchanger, a high-low pressure heat exchanger, a plurality of pressure reducing devices, and a connection between them are connected. A heat source unit, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, a heat storage unit having a refrigerant body, a load-side heat exchanger, and a pressure reducing device. In a refrigerant circuit composed of load units, a high and low pressure heat exchanger is used during cold storage, so that it is released into the ambient air in the middle of the path from the outlet of the heat storage tank heat transfer tube, which is a conventional evaporator, to the compressor suction side. The refrigeration capacity can be improved by collecting the cold heat that has been collected on the high-pressure liquid side of the refrigeration cycle.
[0101]
Embodiment 6 FIG.
Embodiment 5 of the present invention will be described below with reference to the drawings.
FIG. 13 is a diagram showing Embodiment 6 and is a schematic diagram of a refrigeration cycle of a heat storage system.
In FIG. 13, 1 is a compressor, 2 is a four-way valve, 3 is a heat source side heat exchanger (including a blower fan), 5a, 5c and 5d are decompressors, 6 is a heat storage tank, 7 is a heat storage tank heat transfer tube, 8 Is a refrigerant storage body, 9 is a load side heat exchanger (including a blower fan), 10e, 10h to 10k are on-off valves, 11 is an accumulator, 15 is a high / low pressure heat exchanger, 17 is a gas-liquid separator, and X is a heat source unit. , Y is a load unit, Z is a heat storage unit, and the heat source unit X, the load unit Y, and the heat storage unit Z constitute a refrigeration cycle.
[0102]
Next, the operation of the refrigerant circuit incorporating the high-low pressure heat exchanger 15 as the composition regulator and the gas-liquid separator 17 during cold storage will be described with reference to FIG.
During cold storage, the on-off valve 10h is opened, the on-off valves 10i, 10j, and 10k are closed, and the heat source unit X and the heat storage unit Z constitute a refrigeration cycle.
[0103]
The on-off valve 10e is opened. The high-pressure gas refrigerant compressed and discharged by the compressor 1 flows into the heat source side heat exchanger 3 through the four-way valve 2. The heat source side heat exchanger 3 is condensed by heat exchange with ambient air having a low temperature relative to the temperature of the refrigerant circulating in the heat exchanger, and at the outlet of the heat source side heat exchanger 3, a high-pressure liquid refrigerant or a high-pressure two-phase refrigerant The high-pressure gas refrigerant separated here flows into the high-low pressure heat exchanger 15, where it heat-exchanges with the low-pressure refrigerant to condense, and flows out as high-pressure liquid refrigerant. Then, the pressure is reduced by the pressure reducing device 5c via the on-off valve 10e, and then flows into the heat storage tank heat transfer tube 7 in a low-pressure two-phase refrigerant state.
[0104]
The heat storage tank heat transfer pipe 7 is evaporated by heat exchange with the heat storage refrigerant body 8 having a temperature higher than the refrigerant temperature circulating in the pipe, and flows out as a low-pressure gas refrigerant at the outlet of the heat storage tank heat transfer pipe 7. Then, it flows into the suction side of the compressor 1 through the accumulator 11.
[0105]
On the other hand, the high-pressure saturated liquid refrigerant separated by the gas-liquid separator 17 is depressurized by the decompression device 5a to become a low-pressure two-phase refrigerant and flows into the high-low pressure heat exchanger 15. Here, heat exchange with the high-pressure refrigerant evaporates to become a low-pressure gas refrigerant and flows into the accumulator 11.
[0106]
The composition is adjusted only during cold storage, not during other operations.
The effect of the composition adjustment and its mechanism will be described.
If a mixed refrigerant containing a large amount of R32 component of the low boiling point refrigerant is passed through the load side heat exchanger 9 as an evaporator, the refrigerant flow rate can be reduced by increasing the pressure and increasing the density of the refrigerant. The COP of the cycle can be improved.
[0107]
Therefore, the composition is adjusted using the gas-liquid separator 17. In the gas-liquid separator 17, the composition of the saturated gas is increased in low-boiling R32 that is easily gasified, and conversely, the composition of the saturated liquid is increased in high-boiling R134a that is difficult to gasify. Therefore, in order to distribute the saturated gas refrigerant having a large amount of R32 to the load-side heat exchanger 9 as an evaporator, the high- and low-pressure heat exchanger 15 exchanges heat to form a liquid refrigerant and then depressurizes the load-side heat exchanger 9. Let it flow into the inlet. On the other hand, the saturated liquid refrigerant with a small amount of R32 is decompressed to a low-pressure two-phase refrigerant to bypass the load-side heat exchanger 9 as an evaporator and return to the suction side of the compressor 1, and then the high-low pressure heat exchange is performed. Heat is exchanged in the vessel 16 and flows into the suction side of the compressor 1 as a low-pressure gas refrigerant.
[0108]
As described above, if the heat storage refrigeration cycle shown in Embodiment 6 is used, the compressor, the four-way valve, the heat source side heat exchanger, the high-low pressure heat exchanger and the gas-liquid separator as the composition adjusting device, A heat source unit having a high-low pressure heat exchanger, a plurality of decompression devices, and a pipe connecting them, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, and a refrigerant storage body, In a refrigerant circuit composed of a load unit having a heat storage unit, a load-side heat exchanger, a pressure reducing device, and a pipe connecting them, the intake pressure is increased by adjusting the composition during cold storage, The COP of the cycle can be improved.
[0109]
【The invention's effect】
A heat storage type refrigeration cycle according to the present invention includes a plurality of compressors, a four-way valve, a heat source side heat exchanger, a plurality of gas-liquid separators, a plurality of decompression devices, and a pipe connecting them. A heat storage unit having a heat source unit, a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, a refrigerant storage body, a load-side heat exchanger, a decompression device, a pipe connecting them, A multi-stage compression operation and a single-stage compression operation using a plurality of compressors depending on the situation, thereby reducing the operation cost by improving the COP at a low equipment cost. The effect to be achieved is obtained.
[0110]
In addition, a heat source unit having a plurality of compressors, a four-way valve, a heat source side heat exchanger, a plurality of intermediate coolers, a plurality of pressure reducing devices, and a pipe connecting them, a heat storage tank, and a heat storage A heat storage unit having a heat transfer pipe in a tank, a pipe connecting them, and a refrigerant storage body, a load-side heat exchanger, a decompression device, a pipe connecting them, and a load unit having a situation Accordingly, by selecting and executing the multi-stage compression operation and the single-stage compression operation using a plurality of compressors, it is possible to obtain an effect of realizing a reduction in operation cost by improving COP at a low equipment cost.
[0111]
Also, a heat source unit having a plurality of compressors, a four-way valve, a heat source side heat exchanger, an economizer, a plurality of pressure reducing devices, and a pipe connecting them, a heat storage tank, and a heat transfer pipe in the heat storage tank And a heat storage unit having a pipe connecting them, a refrigerant storage body, a load side heat exchanger, a decompression device, and a load unit having a pipe connecting them, and depending on the situation, By selecting and executing the multi-stage compression operation and the single-stage compression operation using a plurality of compressors, it is possible to obtain an effect of realizing a reduction in operation cost by improving COP at a low equipment cost.
[0112]
In addition, in the case of multi-stage compression operation, a plurality of compressors to be used are connected in series, and in the case of single-stage compression operation, a plurality of compressors to be used are connected in parallel, and a compression method is selected according to the situation. The effect which implement | achieves reduction of an installation cost and an operating cost is acquired.
[0113]
In addition, the capacity of each compressor used when performing multistage compression operation is set based on the flow rate ratio of each compressor when performing multistage compression operation during cold storage, so that the effect of improving COP during cold storage can be obtained. .
[0114]
Further, the predetermined compressor is a variable capacity compressor, and the remaining compressor is a constant capacity compressor, so that the effect of reducing the equipment cost can be obtained.
[0115]
The operation method of the regenerative refrigeration cycle according to the present invention can achieve the effect of improving COP during cold storage by performing multistage compression operation during cold storage and single-stage compression operation during times other than cold storage.
[0116]
The compressor discharge refrigerant pressure that is the highest pressure among the plurality of compressors and the suction refrigerant pressure of the compressor that is the lowest pressure are detected, and the ratio of the discharge refrigerant pressure and the suction refrigerant pressure. When the compression ratio is smaller than a predetermined value, the single-stage compression operation is selected. When the compression ratio is larger than the predetermined value, the multi-stage compression operation is selected, and multistage compression and single-stage compression are performed. In one compression method, if a compression method different from the current operation is selected, the compression method is changed after the lapse of a predetermined control time, and then the operation method that does not allow the change of the compression method during the predetermined protection control time, The effect of realizing low operating cost with low equipment cost can be obtained.
[0117]
A heat storage refrigeration cycle according to the present invention includes a compressor, a four-way valve, a heat source side heat exchanger, an expansion power recovery device, a plurality of decompression devices, and a heat source unit having a pipe connecting them, Load unit having a heat storage tank, a heat transfer pipe in the heat storage tank, a pipe connecting them, and a heat storage unit, a heat storage unit, a load-side heat exchanger, a decompression device, and a pipe connecting them And by using the expansion power recovery device during cold storage, an effect of improving COP during cold storage can be obtained.
[0118]
Also, a heat source unit having a compressor, a four-way valve, a heat source side heat exchanger, a high and low pressure heat exchanger, a plurality of pressure reducing devices, and piping connecting them, a heat storage tank, and a heat storage tank A heat storage unit having a heat transfer pipe, a pipe connecting them, and a refrigerant storage body, a load side heat exchanger, a decompression device, and a load unit having a pipe connecting them, and during cold storage By using a high and low pressure heat exchanger, the effect of improving COP during cold storage can be obtained.
[0119]
Further, a heat source unit having a compressor, a four-way valve, a heat source side heat exchanger, a composition adjusting device, a plurality of pressure reducing devices, and a pipe connecting them, a heat storage tank, and a heat transfer tube in the heat storage tank And a load storage unit having a heat storage unit having a refrigerant storage body, a load-side heat exchanger, a decompression device, and a pipe connecting them. In the case of a boiling mixed refrigerant, the effect of improving COP during cold storage can be obtained by adjusting the composition using a composition adjusting device during cold storage.
[Brief description of the drawings]
FIG. 1 shows the first embodiment, and is a circuit diagram of a refrigeration cycle of a heat storage system.
FIG. 2 shows the first embodiment and is a Ph diagram of single-stage compression operation.
FIG. 3 is a diagram showing the first embodiment and is a Ph diagram of multi-stage compression operation;
FIG. 4 is a diagram showing the first embodiment and is a diagram showing a compression ratio and a ratio of a multi-stage compression COP and a single-stage compression COP.
FIG. 5 is a diagram showing the second embodiment and is a circuit diagram of a refrigeration cycle of a heat storage system.
FIG. 6 is a diagram illustrating the third embodiment and is a circuit diagram of a refrigeration cycle of the heat storage system.
FIG. 7 shows the fourth embodiment and is a circuit diagram of a refrigeration cycle of the heat storage system.
FIG. 8 shows the fourth embodiment, and is another circuit diagram of the refrigeration cycle of the heat storage system.
FIG. 9 is a diagram showing a fourth embodiment and is a schematic diagram of an ejector.
FIG. 10 is a diagram showing the fourth embodiment and is a Ph diagram;
FIG. 11 shows the fifth embodiment and is a circuit diagram of a refrigeration cycle of the heat storage system.
FIG. 12 is a diagram illustrating the fifth embodiment, and is a diagram illustrating specific enthalpies of an evaporator inlet, an outlet, and an elevation difference heat exchanger outlet;
FIG. 13 shows the sixth embodiment and is a circuit diagram of the refrigeration cycle of the heat storage system.
FIG. 14 is a refrigerant circuit diagram of a conventional heat storage system.
[Explanation of symbols]
1, 1a, 1b Compressor, 2 Four-way valve, 3 Heat source side heat exchanger, 4a Gas-liquid separator, 4b Intermediate cooler, 4c Economizer, 5a, 5c, 5d Pressure reducing device, 6 heat storage tank, 7 Heat storage tank heat transfer tube , 8 Regenerator, 9 Load side heat exchanger, 10a to 10k on-off valve, 11 Accumulator, 12 Gas-liquid separator, 13 Ejector, 15 High / low pressure heat exchanger, 17 Gas-liquid separator, 18 Ejector suction part.

Claims

It is an operation method of a regenerative refrigerating cycle that can be executed by selecting either a multistage compression operation or a single stage compression operation using a plurality of compressors,
Calculate the refrigerant compression ratio or pressure ratio at each predetermined detection time,
When the calculated compression ratio or pressure ratio is smaller than a predetermined threshold, select a single-stage compression operation, and when larger than the threshold , select a multi-stage compression operation,
When a compression method different from the compression method during operation is selected, after the compression method is changed, until the predetermined protection control time longer than the time from the time when the compression method is changed to the next detection time elapses, A method of operating a regenerative refrigerating cycle, characterized in that no change is allowed.

In the operation method of the heat storage refrigeration cycle,
No change in compression method beyond a predetermined number of times during the period from when the heat storage refrigeration cycle starts to when it stops.
The operation method of the regenerative refrigeration cycle according to claim 1.

At each predetermined detection time, the refrigerant pressure at the discharge portion of the compressor at the most downstream of the refrigerant flow in the plurality of compressors and the refrigerant pressure at the suction portion of the compressor at the most upstream are detected, Calculating a compression ratio which is a ratio of the discharge refrigerant pressure and the suction refrigerant pressure ;
The heat storage type according to claim 1 or 2, wherein a single-stage compression operation is selected when the calculated compression ratio is smaller than a predetermined threshold value , and a multi-stage compression operation is selected when the calculated compression ratio is larger than the threshold value. How to operate the refrigeration cycle.

The heat storage refrigeration cycle is a heat storage refrigeration cycle in which a plurality of compressors, a heat source side heat exchanger, a gas-liquid separator, a heat storage tank, and a load side heat exchanger are connected by piping,
At the time of multistage compression operation, the refrigerant condensed in the heat source side heat exchanger is gas-liquid separated by the gas-liquid separator, and the separated gas refrigerant is caused to flow into a pipe connecting the plurality of compressors and separated. Flowing liquid refrigerant into the heat storage layer,
During single-stage compression operation, the refrigerant condensed in the heat source side heat exchanger is allowed to flow into the heat storage layer without passing through the gas-liquid separator.
The operation method of the regenerative refrigeration cycle according to any one of claims 1 to 3.

The heat storage refrigeration cycle is a heat storage refrigeration cycle in which a plurality of compressors, a heat source side heat exchanger, an intercooler, a heat storage tank, and a load side heat exchanger are connected by piping,
During multistage compression operation, the refrigerant condensed in the heat source side heat exchanger is cooled by the intermediate cooler and flows into the heat storage layer,
During single-stage compression operation, the refrigerant condensed in the heat source side heat exchanger is allowed to flow into the heat storage layer without being cooled by the intermediate cooler.
The operation method of the regenerative refrigeration cycle according to any one of claims 1 to 3.

The heat storage refrigeration cycle is a heat storage refrigeration cycle in which a plurality of compressors, a heat source side heat exchanger, an economizer, a heat storage tank, and a load side heat exchanger are connected by piping,
At the time of multistage compression operation, the refrigerant condensed in the heat source side heat exchanger is separated into gas and liquid by the economizer, and the separated gas refrigerant is caused to flow into a pipe connecting the plurality of compressors, and the separated liquid Let the refrigerant flow into the heat storage layer,
The regenerative refrigeration according to any one of claims 1 to 3, wherein during single-stage compression operation, the refrigerant condensed in the heat source side heat exchanger flows into the heat storage layer without passing through the economizer. How to run the cycle.