JP4048853B2

JP4048853B2 - Ejector cycle

Info

Publication number: JP4048853B2
Application number: JP2002200009A
Authority: JP
Inventors: 洋押谷; 裕嗣武内; 美歌齋藤
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2002-07-09
Filing date: 2002-07-09
Publication date: 2008-02-20
Anticipated expiration: 2022-07-09
Also published as: JP2004044849A

Description

【０００１】
【発明の属する技術分野】
本発明は、エジェクタサイクルに関するものである。
【０００２】
【従来の技術及び発明が解決しようとする課題】
エジェクタサイクルとは、周知のごとく、エジェクタにて冷媒を減圧膨張させて蒸発器にて蒸発した気相冷媒を吸引するとともに、膨張エネルギーを圧力エネルギーに変換して圧縮機の吸入圧を上昇させる蒸気圧縮式冷凍機である。
【０００３】
具体的には、エジェクタサイクルでは、圧縮機→放熱器→エジェクタ→気液分離器→圧縮機の順に循環する冷媒流れ（以下、駆動流と呼ぶ。）と、気液分離器→蒸発器→エジェクタ→気液分離器の順に循環する冷媒流れ（以下、吸引流と呼ぶ。）とが存在し、吸引流は圧縮機にて圧縮された高圧冷媒の有するエネルギーを利用したエジェクタのポンプ作用（ＪＩＳＺ８１２６番号２．１．２．３等参照）により循環させられる。
【０００４】
ところで、膨張弁等の減圧手段により等エンタルピ的に冷媒を減圧する蒸気圧縮式冷凍機（以下、膨張弁サイクルと呼ぶ。）では、膨張弁を流出して蒸発器に流れ込んだ冷媒を圧縮機が直接的に吸引するのに対して、エジェクタサイクルでは、圧縮機は蒸発器内の冷媒を吸引するのではなく、気液分離器内の冷媒を吸引する。
【０００５】
そして、エジェクタサイクルでは、蒸発器に供給する液相冷媒は勿論のこと、冷媒と共に循環する冷凍機油を圧縮機に戻すため、比較的多量の液相成分を気液分離器内に蓄えて気液分離器内で冷凍機油と液相冷媒とを分離して圧縮機に冷凍機油を戻している。
【０００６】
このため、エジェクタサイクル用の気液分離器では、多量の液相成分を気液分離器に蓄える必要があるため、気液分離器の小型化を図ることが難しいと言う問題を有している。
【０００７】
因みに、冷凍機油とは、圧縮機の摺動部を潤滑する潤滑油であり、一般的な蒸気圧縮式冷凍機では、冷媒に冷凍機油を混合することにより圧縮機内の摺動部を潤滑する。
【０００８】
本発明は、上記点に鑑み、第１には、従来と異なる新規なエジェクタサイクルを提供し、第２には、エジェクタサイクル用の気液分離器の小型化を図ることを目的とする。
【０００９】
【課題を解決するための手段】
本発明は、上記目的を達成するために、請求項１に記載の発明では、低温側の熱を高温側に移動させる蒸気圧縮式のエジェクタサイクルであって、圧縮機（１０）から吐出した高圧冷媒の熱を放熱する高圧側熱交換器（２０）と、低圧冷媒を蒸発させる低圧側熱交換器（３０）と、高圧冷媒を等エントロピ的に減圧膨張させるノズル（４１）を有し、ノズル（４１）から噴射する高い速度の冷媒流により低圧側熱交換器（３０）にて蒸発した気相冷媒を吸引するとともに、膨張エネルギーを圧力エネルギーに変換して圧縮機（１０）の吸入圧を上昇させるエジェクタ（４０）と、エジェクタ（４０）から流出した冷媒を気相冷媒と液相冷媒とに分離し、気相冷媒用出口が圧縮機（１０）の吸引側に接続され、液相冷媒用出口が低圧側熱交換器（３０）に接続された気液分離手段（５０）と、低圧側熱交換器（３０）の冷媒出口側と圧縮機（１０）の冷媒吸入側とを繋ぐ冷媒通路（８０）と、冷媒通路（８０）に設けられ、低圧側熱交換器（３０）の冷媒出口側がら圧縮機（１０）の冷媒吸入側にのみ冷媒が流れることを許容するバルブ（７１）とを備え、冷媒通路（８０）を構成する配管部材、バルブ（７１）及び気液分離器（５０）が一体化されていることを特徴とする。
【００１０】
これにより、蒸発器（３０）内に滞留する冷凍機油を圧縮機（１０）に戻すことができるので、気液分離器（５０）に多量の液相成分を蓄える必要がなく、気液分離器（５０）の小型化を図ることができるとともに、従来と異なる新規なエジェクタサイクルを得ることができる。
【００１１】
請求項２に記載の発明では、低温側の熱を高温側に移動させる蒸気圧縮式のエジェクタサイクルであって、圧縮機（１０）から吐出した高圧冷媒の熱を放熱する高圧側熱交換器（２０）と、低圧冷媒を蒸発させる低圧側熱交換器（３０）と、高圧冷媒を等エントロピ的に減圧膨張させるノズル（４１）を有し、ノズル（４１）から噴射する高い速度の冷媒流により低圧側熱交換器（３０）にて蒸発した気相冷媒を吸引するとともに、膨張エネルギーを圧力エネルギーに変換して圧縮機（１０）の吸入圧を上昇させるエジェクタ（４０）と、エジェクタ（４０）から流出した冷媒を気相冷媒と液相冷媒とに分離し、気相冷媒用出口が圧縮機（１０）の吸引側に接続され、液相冷媒用出口が低圧側熱交換器（３０）に接続された気液分離手段（５０）と、低圧側熱交換器（３０）の冷媒出口側と圧縮機（１０）の冷媒吸入側とを繋ぐ冷媒通路（８０）と、冷媒通路（８０）に設けられ、低圧側熱交換器（３０）の冷媒出口側の圧力が圧縮機（１０）の冷媒吸入側の圧力より大きくなり、かつ、その圧力差が所定圧力差以上となったときに、冷媒通路（８０）を開くバルブ（７１）とを備え、冷媒通路（８０）を構成する配管部材、バルブ（７１）及び気液分離器（５０）が一体化されていることを特徴とする。
【００１２】
これにより、蒸発器（３０）内に滞留する冷凍機油を圧縮機（１０）に戻すことができるので、気液分離器（５０）に多量の液相成分を蓄える必要がなく、気液分離器（５０）の小型化を図ることができるとともに、従来と異なる新規なエジェクタサイクルを得ることができる。
【００１３】
請求項３に記載の発明では、低温側の熱を高温側に移動させる蒸気圧縮式のエジェクタサイクルであって、圧縮機（１０）から吐出した高圧冷媒の熱を放熱する高圧側熱交換器（２０）と、低圧冷媒を蒸発させる低圧側熱交換器（３０）と、高圧冷媒を等エントロピ的に減圧膨張させるノズル（４１）を有し、ノズル（４１）から噴射する高い速度の冷媒流により低圧側熱交換器（３０）にて蒸発した気相冷媒を吸引するとともに、膨張エネルギーを圧力エネルギーに変換して圧縮機（１０）の吸入圧を上昇させるエジェクタ（４０）と、エジェクタ（４０）から流出した冷媒を気相冷媒と液相冷媒とに分離し、気相冷媒用出口が圧縮機（１０）の吸引側に接続され、液相冷媒用出口が低圧側熱交換器（３０）に接続された気液分離手段（５０）と、低圧側熱交換器（３０）の冷媒出口側と圧縮機（１０）の冷媒吸入側とを繋ぐ冷媒通路（８０）と、低圧側熱交換器（３０）の冷媒出口側の圧力が圧縮機（１０）の冷媒吸入側の圧力より大きくなり、かつ、その圧力差が所定圧力差以上となったときに、冷媒通路（８０）に冷媒を流す電気式のバルブ（７３、７４）とを備え、冷媒通路（８０）を構成する配管部材、バルブ（７３、７４）及び気液分離器（５０）が一体化されていることを特徴とする。
【００１４】
これにより、蒸発器（３０）内に滞留する冷凍機油を圧縮機（１０）に戻すことができるので、気液分離器（５０）に多量の液相成分を蓄える必要がなく、気液分離器（５０）の小型化を図ることができるとともに、従来と異なる新規なエジェクタサイクルを得ることができる。
【００１６】
因みに、上記各手段の括弧内の符号は、後述する実施形態に記載の具体的手段との対応関係を示す一例である。
【００１７】
【発明の実施の形態】
（第１実施形態）
本実施形態は、本発明に係るエジェクタサイクルを、食品を冷蔵・冷凍保存するショーケース用の蒸気圧縮式冷凍機に適用したものであって、図１はエジェクタサイクルの模式図である。
【００１８】
圧縮機１０は冷媒を吸入圧縮する電動式の圧縮機であり、放熱器２０は圧縮機１０から吐出した高温・高圧の冷媒と室外空気とを熱交換して冷媒を冷却する高圧側熱交換器である。
【００１９】
また、蒸発器３０は、ショーケース内に吹き出す空気と低圧冷媒とを熱交換させて液相冷媒を蒸発させることにより冷凍能力を発揮する低圧側熱交換器であり、エジェクタ４０は放熱器２０から流出する冷媒を減圧膨張させて蒸発器３０にて蒸発した気相冷媒を吸引するとともに、膨張エネルギーを圧力エネルギーに変換して圧縮機１０の吸入圧を上昇させるエジェクタである。
【００２０】
なお、エジェクタ４０は、図２に示すように、流入する高圧冷媒の圧力エネルギーを速度エネルギーに変換して冷媒を等エントロピ的に減圧膨張させるノズル４１、ノズル４１から噴射する高い速度の冷媒流の巻き込み作用により蒸発器３０にて蒸発した気相冷媒を吸引しながら、ノズル４１から噴射する冷媒流とを混合する混合部４２、及びノズル４１から噴射する冷媒と蒸発器３０から吸引した冷媒とを混合させながら速度エネルギーを圧力エネルギーに変換して冷媒の圧力を昇圧させるディフューザ４３等からなるものである。
【００２１】
このとき、混合部４２においては、駆動流の運動量と吸引流の運動量との和が保存されるように駆動流と吸引流とが混合するので、混合部４２においても冷媒の圧力が（静圧）が上昇する。
【００２２】
一方、ディフューザ４３においては、通路断面積を徐々に拡大することにより、冷媒の速度エネルギ（動圧）を圧力エネルギ（静圧）に変換するので、エジェクタ４０においては、混合部４２及びディフューザ４３の両者にて冷媒圧力を昇圧する。そこで、以下、混合部４２とディフューザ４３とを総称して昇圧部と呼ぶ。
【００２３】
因みに、本実施形態では、ノズル４１から噴出する冷媒の速度を音速以上まで加速するために、通路途中に通路面積が最も縮小した喉部４１ａを有するラバールノズル（流体工学（東京大学出版会）参照）を採用しているが、勿論、先細ノズルを採用してもよいことは言うまでもない。
【００２４】
また、図１中、気液分離器５０はエジェクタ４０から流出した冷媒が流入するとともに、その流入した冷媒を気相冷媒と液相冷媒とに分離して冷媒を蓄える気液分離手段であり、気液分離器５０の気相冷媒流出口は圧縮機１０の吸引側に接続され、液相冷媒流出口は蒸発器３０側に接続されている。
【００２５】
絞り６０は気液分離器５０から流出した液相冷媒を減圧する減圧手段であり、オイル戻し通路７０は、蒸発器３０の冷媒出口側と圧縮機１０の冷媒吸入側とを繋ぐ冷媒通路であり、オイル戻し通路７０には、冷媒が蒸発器３０の冷媒出口側から圧縮機１０の冷媒吸入側に向かって流れることのみを許容する逆止弁７１が設けられており、この逆止弁７１が開閉することによりオイル戻し通路７０に冷媒を流す場合と流さない場合とが制御される。
【００２６】
ここで、逆止弁７１は、弁口を開閉する弁体７１ａ、及び弁体７１ａに弁口を閉じる向きの弾性力を作用させるバネ７１ｂを有して構成されたもので、弁体７１ａ及びバネ７１ｂは、蒸発器３０の冷媒出口側の圧力が圧縮機１０の冷媒吸入側の圧力より大きくなり、かつ、その圧力差が所定圧力差以上となったときにオイル戻し通路７０を開くように設定されている。
【００２７】
なお、図１の逆止弁７１は、ＪＩＳＢ０１２５に従った逆止弁の記号であり、図１に示された弁体７１ａ及びバネ７１ｂの形状は、必ずしも実際の形状を示すものではない。
【００２８】
また、内部熱交換器８０は、放熱器２０から流出した高圧冷媒と圧縮機１０に吸入される低圧冷媒とを熱交換する熱交換器であり、流量制御弁９０は、ノズル４１の入口側に蒸発器３０の冷媒出口側における冷媒過熱度が所定値となるように絞り開度を制御するバルブである。
【００２９】
因みに、本実施形態では、冷媒を二酸化炭素とするとともに、図３に示すように、圧縮機１０にてノズル４１に流入する高圧冷媒を冷媒の臨界圧力以上まで昇圧している。因みに、図３の●で示される符号は、図１に示す●で示される符号位置における冷媒の状態を示すものである。
【００３０】
次に、本実施形態に係るサイクルの作動及び特徴点を述べる。
【００３１】
１．通常運転モード（図３参照）
圧縮機１０から吐出した冷媒を放熱器２０側に循環させる。これにより、放熱器２０にて冷却された冷媒は、エジェクタ４０のノズル４１にて等エントロピ的に減圧膨張して、音速以上の速度で混合部４２内に流入する。
【００３２】
そして、混合部４２に流入した高速冷媒の巻き込み作用に伴うポンプ作用により、蒸発器３０内で蒸発した冷媒が混合部４２内に吸引されるため、低圧側の冷媒が気液分離器５０→絞り６０→蒸発器３０→エジェクタ４０（昇圧部）→気液分離器５０の順に循環する。
【００３３】
一方、蒸発器３０から吸引された冷媒（吸引流）とノズル４１から吹き出す冷媒（駆動流）とは、混合部４２にて混合しながらディフューザ４３にてその動圧が静圧に変換されて気液分離器５０に戻る。
【００３４】
２．オイル戻しモード
本モードは、冷媒に混合された状態でエジェクタサイクル内を循環する冷凍機油が蒸発器３０内に所定量以上滞留した場合や外気温度が低下した場合等のエジェクタ効率ηｅが低下した場合又はエジェクタ４０のポンプ作用が低下した場合に自動的に実行されるモードである。
【００３５】
因みに、エジェクタ効率ηｅとは、放熱器２０を流通する冷媒の質量流量Ｇｎとノズル４１の出入口のエンタルピ差Δｉｅとの積を分母とし、分子には、圧縮機１０の仕事としてエネルギがどの程度回収されたかを示す冷媒流量Ｇｎと蒸発器３０を流通する冷媒の質量流量Ｇｅとの和とエジェクタ４０での圧力回復ΔＰを置いて定義したものである。
【００３６】
すなわち、エジェクタ４０のポンプ作用が十分に大きいときには、エジェクタ４０での圧力回復ΔＰ、つまりエジェクタ４０での昇圧量ΔＰが大きいため、図４に示すように、逆止弁７１を挟んで圧縮機１０の冷媒吸入側の圧力Ｐ３が相対的に蒸発器３０の冷媒出口側の圧力Ｐ１より大きくなり、オイル戻し通路７０は逆止弁７１により閉じられ、オイル戻し通路７０に冷媒は流れない。
【００３７】
しかし、エジェクタ４０のポンプ作用が小さくなると、逆止弁７１を挟んで蒸発器３０の冷媒出口側の圧力Ｐ１が相対的に圧縮機１０の冷媒吸入側の圧力Ｐ３より大きくなるため、図５に示すように、逆止弁７１が開き、オイル戻し通路７０に冷媒が流れる。
【００３８】
したがって、蒸発器３０の冷媒出口側が直接的に圧縮機１０の吸入側と連通するので、エジェクタ４０のポンプ作用が小さくても、蒸発器３０内に滞留していた冷凍機油が圧縮機１０に向かって流れ、冷凍機油の滞留が解消される。
【００３９】
そして、蒸発器３０内の冷凍機油が減少すると、蒸発器３０での冷凍能力が増大して吸引流及び駆動流の流量が増大するため、エジェクタ４０のポンプ作用が大きくなり、逆止弁７１を挟んで圧縮機１０の冷媒吸入側の圧力Ｐ３が相対的に蒸発器３０の冷媒出口側の圧力Ｐ１より大きくなる。
【００４０】
つまり、蒸発器３０内の冷凍機油が減少すると、逆止弁７１が閉じて自動的にオイル戻しモードから通常運転モードに移行し、逆に、蒸発器３０内の多量の冷凍機油が滞留すると、逆止弁７１が開いて自動的に通常運転モードからオイル戻しモードに移行する。
【００４１】
以上に述べたように、本実施形態では、蒸発器３０内に滞留する冷凍機油を所定量以下に制御して圧縮機１０に十分な量の冷凍機油を戻すことができるので、気液分離器５０に多量の液相成分を蓄える必要がなく、気液分離器５０の小型化を図ることができる。
【００４２】
（第２実施形態）
本実施形態は、図６に示すように、逆止弁７１のバネ７１ｂを廃止する、又はバネ７１ｂの弾性力を極めて小さくすることにより、蒸発器３０の冷媒出口側の圧力が圧縮機１０の冷媒吸入側の圧力より大きくなったときにオイル戻し通路７０を開くように構成したものである。
【００４３】
（第３実施形態）
第１実施形態では、機械式バルブをなす逆止弁７１によりオイル戻し通路７０を開閉したが、本実施形態は、図７に示すように、逆止弁７１に代えて電磁弁７３とするとともに、圧力センサ７２ａ、７２ｂによりエジェクタ４０での昇圧量ΔＰを検出し、エジェクタ４０での昇圧量ΔＰが所定値以下となったときに電磁弁７３を開き、エジェクタ４０での昇圧量ΔＰが所定値を超えたときに電磁弁７３を閉じるようにしたものである。
【００４４】
なお、本実施形態は、電磁弁７３を閉じる時の所定値と電磁弁７３を閉じる時の所定値とを相違させても実施することができる。
【００４５】
また、本実施形態では、エジェクタ４０での昇圧量ΔＰをパラメータとして電磁弁７３の開閉制御を行ったが、本実施形態はこれに限定されるものではなく、例えば圧縮機１０の回転数、冷媒温度及び冷媒圧力等からエジェクタ効率ηｅを算出し、エジェクタ効率ηｅが所定値以下となったときに電磁弁７３を開き、エジェクタ効率ηｅが所定値を超えたときに電磁弁７３を閉じるようにしてもよい。この際、電磁弁７３を閉じる時のエジェクタ効率ηｅの所定値と電磁弁７３を閉じる時のエジェクタ効率ηｅの所定値とを相違させてもよいことは言うまでもない。
【００４６】
（第４実施形態）
本実施形態は第３実施形態の変形例であり、具体的には、図８、９に示すように、低圧側冷媒通路とオイル戻し通路７０との分岐部又は合流部に三方式の電磁弁７４を設けて、エジェクタ４０での昇圧量ΔＰが所定値以下となったときに電磁弁８２を開き、エジェクタ４０での昇圧量ΔＰが所定値を超えたときに電磁弁７４を閉じるようにしたものである。
【００４７】
なお、図８は蒸発器３０の出口側の冷媒分岐部に電磁弁７４を配置した例であり、図９はエジェクタ４０の出口側の冷媒合流部に電磁弁７４を配置した例である。
【００４８】
（第５実施形態）
本実施形態は、図１０に示すように、オイル戻し通路７０を構成する配管、エジェクタ４０、気液分離器５０、逆止弁７１及び流量制御弁９０等（図１の破線で囲まれた箇所）を一体化したものである。
【００４９】
なお、図１０は第１実施形態に対して本実施形態を適用したものであったが、本実施形態はこれに限定されるものではなく、第２〜４実施形態に対しても適用することができることは言うまでもない。
【００５０】
（その他の実施形態）
上述の実施形態では、二酸化炭素を冷媒としたが、本発明はこれに限定されるものではなく、例えば冷媒として炭化水素やフロン等を用いてもよい。
【００５１】
また、上述の実施形態では、高圧側冷媒圧力を臨界圧力以上としたが、本発明はこれに限定されるものではない。
【００５２】
また、上述の実施形態では、本発明に係るエジェクタサイクルを、食品を冷蔵・冷凍保存するショーケース用の蒸気圧縮式冷凍機に適用したが、本発明の適用はこれに限定されるものではなく、例えば空調装置にも適用することができる。
【００５３】
また、本発明は、オイル戻しモード時に、圧縮機１０により蒸発器３０内の冷凍機油を直接的に吸引するものであるから、上述の実施形態に限定されるものではない。
【００５４】
また、流量制御弁９０及び内部熱交換器８０のうち少なくとも一方を廃止してもよい。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係るエジェクタサイクルの模式図である。
【図２】本発明の実施形態に係るエジェクタの模式図である。
【図３】ｐ−ｈ線図である。
【図４】本発明の第１実施形態に係るエジェクタサイクルの作動説明図である。
【図５】本発明の第１実施形態に係るエジェクタサイクルの作動説明図である。
【図６】本発明の第２実施形態に係るエジェクタサイクルの模式図である。
【図７】本発明の第３実施形態に係るエジェクタサイクルの模式図である。
【図８】本発明の第４実施形態に係るエジェクタサイクルの模式図である。
【図９】本発明の第４実施形態に係るエジェクタサイクルの模式図である。
【図１０】本発明の第５実施形態に係るエジェクタサイクルの特徴を示す説明図である。
【符号の説明】
１０…圧縮機、２０…放熱器、３０…蒸発器、４０…エジェクタ、
５０…気液分離器、６０…絞り、７０…オイル戻し通路、７１…逆止弁。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ejector cycle.
[0002]
[Prior art and problems to be solved by the invention]
As is well known, the ejector cycle is a vapor that decompresses and expands the refrigerant in the ejector and sucks the gas-phase refrigerant evaporated in the evaporator, and converts the expansion energy into pressure energy to increase the suction pressure of the compressor. This is a compression refrigerator.
[0003]
Specifically, in the ejector cycle, a refrigerant flow (hereinafter referred to as a driving flow) that circulates in the order of a compressor, a radiator, an ejector, a gas-liquid separator, and a compressor, and a gas-liquid separator, an evaporator, and an ejector. → There is a refrigerant flow (hereinafter referred to as suction flow) that circulates in the order of the gas-liquid separator, and the suction flow uses the energy of the high-pressure refrigerant compressed by the compressor (JIS Z). 8126 number 2.1.2.3 etc.).
[0004]
By the way, in a vapor compression type refrigerator (hereinafter referred to as an expansion valve cycle) in which the refrigerant is decompressed in an enthalpy manner by decompression means such as an expansion valve, the compressor removes the refrigerant flowing out of the expansion valve and flowing into the evaporator. In contrast to the direct suction, in the ejector cycle, the compressor does not suck the refrigerant in the evaporator but sucks the refrigerant in the gas-liquid separator.
[0005]
In the ejector cycle, not only the liquid-phase refrigerant supplied to the evaporator but also the refrigeration oil circulating with the refrigerant is returned to the compressor, so that a relatively large amount of liquid-phase component is stored in the gas-liquid separator. In the separator, the refrigeration oil and the liquid refrigerant are separated, and the refrigeration oil is returned to the compressor.
[0006]
For this reason, the gas-liquid separator for the ejector cycle has a problem that it is difficult to reduce the size of the gas-liquid separator because it is necessary to store a large amount of liquid phase components in the gas-liquid separator. .
[0007]
Incidentally, the refrigeration oil is a lubricating oil that lubricates the sliding portion of the compressor. In a general vapor compression refrigerator, the sliding portion in the compressor is lubricated by mixing the refrigeration oil with a refrigerant.
[0008]
In view of the above points, the present invention firstly provides a new ejector cycle different from the conventional one, and secondly, it aims to reduce the size of the gas-liquid separator for the ejector cycle.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a vapor compression type ejector cycle in which the heat on the low temperature side is moved to the high temperature side, and the high pressure discharged from the compressor (10). A high-pressure side heat exchanger (20) that dissipates the heat of the refrigerant, a low-pressure side heat exchanger (30) that evaporates the low-pressure refrigerant, and a nozzle (41) that decompresses and expands the high-pressure refrigerant isentropically. (41) sucks the vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by the high-speed refrigerant flow injected from the refrigerant, and converts the expansion energy into pressure energy to reduce the suction pressure of the compressor (10). The ejector (40) to be raised, the refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, and the gas phase refrigerant outlet is connected to the suction side of the compressor (10). Outlet for low pressure side heat exchanger 30), a refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10), and a refrigerant passage ( 80) and a valve (71) that allows the refrigerant to flow only from the refrigerant outlet side of the low-pressure side heat exchanger (30) to the refrigerant suction side of the compressor (10) , and the refrigerant passage (80) The piping member, the valve (71), and the gas-liquid separator (50) that constitute the above are integrated .
[0010]
Thereby, since the refrigerating machine oil which retains in an evaporator (30) can be returned to a compressor (10), it is not necessary to store a lot of liquid phase components in a gas-liquid separator (50), and a gas-liquid separator (50) can be reduced in size, and a new ejector cycle different from the conventional one can be obtained.
[0011]
The invention according to claim 2 is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side, and radiates the heat of the high-pressure refrigerant discharged from the compressor (10) ( 20), a low-pressure side heat exchanger (30) for evaporating the low-pressure refrigerant, and a nozzle (41) for decompressing and expanding the high-pressure refrigerant in an isentropic manner, and a high-speed refrigerant flow injected from the nozzle (41) An ejector (40) that sucks the vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) and converts the expansion energy into pressure energy to increase the suction pressure of the compressor (10), and the ejector (40) The refrigerant flowing out of the refrigerant is separated into a gas phase refrigerant and a liquid phase refrigerant, the gas phase refrigerant outlet is connected to the suction side of the compressor (10), and the liquid phase refrigerant outlet is connected to the low pressure side heat exchanger (30). Connected gas-liquid separation means (5 ), The refrigerant passage (80) connecting the refrigerant outlet side of the low-pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10), and the refrigerant passage (80), and the low-pressure side heat exchanger ( 30) A valve (71) that opens the refrigerant passage (80) when the pressure on the refrigerant outlet side of 30) becomes larger than the pressure on the refrigerant suction side of the compressor (10) and the pressure difference becomes a predetermined pressure difference or more. ), And a piping member, a valve (71), and a gas-liquid separator (50) constituting the refrigerant passage (80) are integrated .
[0012]
Thereby, since the refrigerating machine oil which retains in an evaporator (30) can be returned to a compressor (10), it is not necessary to store a lot of liquid phase components in a gas-liquid separator (50), and a gas-liquid separator (50) can be reduced in size, and a new ejector cycle different from the conventional one can be obtained.
[0013]
The invention according to claim 3 is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side, and radiates the heat of the high-pressure refrigerant discharged from the compressor (10) ( 20), a low-pressure side heat exchanger (30) for evaporating the low-pressure refrigerant, and a nozzle (41) for decompressing and expanding the high-pressure refrigerant in an isentropic manner, and a high-speed refrigerant flow injected from the nozzle (41) An ejector (40) that sucks the vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) and converts the expansion energy into pressure energy to increase the suction pressure of the compressor (10), and the ejector (40) The refrigerant flowing out of the refrigerant is separated into a gas phase refrigerant and a liquid phase refrigerant, the gas phase refrigerant outlet is connected to the suction side of the compressor (10), and the liquid phase refrigerant outlet is connected to the low pressure side heat exchanger (30). Connected gas-liquid separation means (5 ), The refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10), and the pressure on the refrigerant outlet side of the low pressure side heat exchanger (30) An electric valve (73, 74) that causes the refrigerant to flow into the refrigerant passage (80) when the pressure on the refrigerant suction side of the compressor (10) becomes larger than the pressure difference and becomes equal to or larger than a predetermined pressure difference; And a piping member, a valve (73, 74), and a gas-liquid separator (50) constituting the refrigerant passage (80) are integrated .
[0014]
Thereby, since the refrigerating machine oil which retains in an evaporator (30) can be returned to a compressor (10), it is not necessary to store a lot of liquid phase components in a gas-liquid separator (50), and a gas-liquid separator (50) can be reduced in size, and a new ejector cycle different from the conventional one can be obtained.
[0016]
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
In the present embodiment, the ejector cycle according to the present invention is applied to a vapor compression refrigerator for a showcase that refrigerates and stores food, and FIG. 1 is a schematic diagram of the ejector cycle.
[0018]
The compressor 10 is an electric compressor that sucks and compresses refrigerant, and the radiator 20 exchanges heat between the high-temperature and high-pressure refrigerant discharged from the compressor 10 and the outdoor air to cool the refrigerant. It is.
[0019]
The evaporator 30 is a low-pressure side heat exchanger that exhibits a refrigerating capacity by heat-exchanging the air blown into the showcase and the low-pressure refrigerant to evaporate the liquid-phase refrigerant. The ejector expands the refrigerant flowing out under reduced pressure and sucks the gas-phase refrigerant evaporated in the evaporator 30 and converts the expansion energy into pressure energy to increase the suction pressure of the compressor 10.
[0020]
As shown in FIG. 2, the ejector 40 converts the pressure energy of the inflowing high-pressure refrigerant into velocity energy and isentropically decompressed and expanded, and the high-speed refrigerant flow injected from the nozzle 41. While sucking the gas-phase refrigerant evaporated in the evaporator 30 by the entrainment action, the mixing unit 42 that mixes the refrigerant flow ejected from the nozzle 41 and the refrigerant ejected from the nozzle 41 and the refrigerant sucked from the evaporator 30 It is composed of a diffuser 43 or the like for increasing the pressure of the refrigerant by converting velocity energy into pressure energy while mixing.
[0021]
At this time, in the mixing unit 42, the driving flow and the suction flow are mixed so that the sum of the momentum of the driving flow and the momentum of the suction flow is preserved. ) Will rise.
[0022]
On the other hand, in the diffuser 43, the velocity energy (dynamic pressure) of the refrigerant is converted into pressure energy (static pressure) by gradually increasing the cross-sectional area of the passage, so that in the ejector 40, the mixing section 42 and the diffuser 43 Both increase the refrigerant pressure. Therefore, hereinafter, the mixing unit 42 and the diffuser 43 are collectively referred to as a boosting unit.
[0023]
Incidentally, in the present embodiment, in order to accelerate the speed of the refrigerant ejected from the nozzle 41 to the sound speed or higher, a Laval nozzle having a throat portion 41a whose passage area is most reduced in the middle of the passage (see Fluid Engineering (Tokyo University Press)) Of course, it goes without saying that a tapered nozzle may be adopted.
[0024]
In FIG. 1, the gas-liquid separator 50 is gas-liquid separation means for storing the refrigerant by flowing the refrigerant flowing out from the ejector 40 and separating the flowing refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant, The gas-phase refrigerant outlet of the gas-liquid separator 50 is connected to the suction side of the compressor 10, and the liquid-phase refrigerant outlet is connected to the evaporator 30 side.
[0025]
The restrictor 60 is a decompression unit that decompresses the liquid-phase refrigerant flowing out from the gas-liquid separator 50, and the oil return passage 70 is a refrigerant passage that connects the refrigerant outlet side of the evaporator 30 and the refrigerant suction side of the compressor 10. The oil return passage 70 is provided with a check valve 71 that only allows the refrigerant to flow from the refrigerant outlet side of the evaporator 30 toward the refrigerant suction side of the compressor 10. By opening and closing, the case where the refrigerant flows through the oil return passage 70 and the case where the refrigerant does not flow are controlled.
[0026]
Here, the check valve 71 includes a valve body 71a that opens and closes the valve opening, and a spring 71b that applies an elastic force to the valve body 71a to close the valve opening. The spring 71b opens the oil return passage 70 when the pressure on the refrigerant outlet side of the evaporator 30 becomes larger than the pressure on the refrigerant suction side of the compressor 10 and the pressure difference becomes a predetermined pressure difference or more. Is set.
[0027]
The check valve 71 in FIG. 1 is a check valve symbol according to JIS B 0125, and the shapes of the valve body 71a and the spring 71b shown in FIG. 1 do not necessarily indicate actual shapes. .
[0028]
The internal heat exchanger 80 is a heat exchanger that exchanges heat between the high-pressure refrigerant flowing out of the radiator 20 and the low-pressure refrigerant sucked into the compressor 10, and the flow control valve 90 is disposed on the inlet side of the nozzle 41. This is a valve that controls the throttle opening so that the degree of refrigerant superheating on the refrigerant outlet side of the evaporator 30 becomes a predetermined value.
[0029]
Incidentally, in this embodiment, while making a refrigerant into a carbon dioxide, as shown in FIG. 3, the high pressure refrigerant | coolant which flows in into the nozzle 41 with the compressor 10 is pressure | voltage-risen more than the critical pressure of a refrigerant | coolant. Incidentally, the symbol indicated by ● in FIG. 3 indicates the state of the refrigerant at the symbol position indicated by ● in FIG.
[0030]
Next, the operation and characteristic points of the cycle according to this embodiment will be described.
[0031]
1. Normal operation mode (see Fig. 3)
The refrigerant discharged from the compressor 10 is circulated to the radiator 20 side. As a result, the refrigerant cooled by the radiator 20 is isentropically decompressed and expanded at the nozzle 41 of the ejector 40 and flows into the mixing unit 42 at a speed equal to or higher than the speed of sound.
[0032]
Then, since the refrigerant evaporated in the evaporator 30 is sucked into the mixing unit 42 by the pumping action accompanying the entrainment action of the high-speed refrigerant flowing into the mixing unit 42, the low-pressure side refrigerant is reduced to the gas-liquid separator 50 → throttle. It circulates in order of 60-> evaporator 30-> ejector 40 (pressure | voltage riser)-> gas-liquid separator 50.
[0033]
On the other hand, the refrigerant sucked from the evaporator 30 (suction flow) and the refrigerant blown out from the nozzle 41 (driving flow) are mixed by the mixing unit 42 and the dynamic pressure thereof is converted into static pressure by the diffuser 43. Return to the liquid separator 50.
[0034]
2. Oil return mode This mode is used when the refrigerating machine oil circulating in the ejector cycle while mixed with the refrigerant stays in the evaporator 30 for a predetermined amount or when the ejector efficiency ηe decreases such as when the outside air temperature decreases. Alternatively, this mode is automatically executed when the pumping action of the ejector 40 is lowered.
[0035]
Incidentally, the ejector efficiency ηe is the product of the mass flow rate Gn of the refrigerant flowing through the radiator 20 and the enthalpy difference Δie at the inlet / outlet of the nozzle 41, and how much energy is recovered as work of the compressor 10 in the numerator. This is defined by adding the sum of the refrigerant flow rate Gn indicating whether or not the refrigerant has flown and the mass flow rate Ge of the refrigerant flowing through the evaporator 30 and the pressure recovery ΔP in the ejector 40.
[0036]
That is, when the pumping action of the ejector 40 is sufficiently large, the pressure recovery ΔP at the ejector 40, that is, the pressure increase ΔP at the ejector 40 is large, so that the compressor 10 is sandwiched by the check valve 71 as shown in FIG. The pressure P3 on the refrigerant suction side becomes relatively larger than the pressure P1 on the refrigerant outlet side of the evaporator 30, the oil return passage 70 is closed by the check valve 71, and the refrigerant does not flow into the oil return passage 70.
[0037]
However, when the pumping action of the ejector 40 is reduced, the pressure P1 on the refrigerant outlet side of the evaporator 30 is relatively larger than the pressure P3 on the refrigerant suction side of the compressor 10 with the check valve 71 interposed therebetween. As shown, the check valve 71 opens and the refrigerant flows through the oil return passage 70.
[0038]
Therefore, since the refrigerant outlet side of the evaporator 30 directly communicates with the suction side of the compressor 10, the refrigerating machine oil staying in the evaporator 30 is directed toward the compressor 10 even if the pumping action of the ejector 40 is small. The refrigeration oil stays away.
[0039]
And if the refrigerating machine oil in the evaporator 30 decreases, the refrigerating capacity in the evaporator 30 increases and the flow rate of the suction flow and the drive flow increases, so the pump action of the ejector 40 increases, and the check valve 71 is turned on. The pressure P3 on the refrigerant suction side of the compressor 10 is relatively larger than the pressure P1 on the refrigerant outlet side of the evaporator 30.
[0040]
That is, when the refrigerating machine oil in the evaporator 30 decreases, the check valve 71 closes and automatically shifts from the oil return mode to the normal operation mode, and conversely, when a large amount of refrigerating machine oil in the evaporator 30 accumulates, The check valve 71 is opened and automatically shifts from the normal operation mode to the oil return mode.
[0041]
As described above, in this embodiment, since the refrigerating machine oil staying in the evaporator 30 can be controlled to a predetermined amount or less and a sufficient amount of refrigerating machine oil can be returned to the compressor 10, the gas-liquid separator It is not necessary to store a large amount of liquid phase component in 50, and the gas-liquid separator 50 can be downsized.
[0042]
(Second Embodiment)
In the present embodiment, as shown in FIG. 6, the pressure on the refrigerant outlet side of the evaporator 30 is reduced by eliminating the spring 71 b of the check valve 71 or making the elastic force of the spring 71 b extremely small. The oil return passage 70 is configured to open when the pressure becomes higher than the refrigerant suction side pressure.
[0043]
(Third embodiment)
In the first embodiment, the oil return passage 70 is opened and closed by a check valve 71 that is a mechanical valve. However, in the present embodiment, an electromagnetic valve 73 is used instead of the check valve 71 as shown in FIG. The pressure sensor 72a, 72b detects the pressure increase amount ΔP at the ejector 40, and when the pressure increase amount ΔP at the ejector 40 falls below a predetermined value, the electromagnetic valve 73 is opened, and the pressure increase amount ΔP at the ejector 40 becomes a predetermined value. The electromagnetic valve 73 is closed when the value exceeds.
[0044]
In addition, this embodiment can be implemented even if the predetermined value when closing the electromagnetic valve 73 and the predetermined value when closing the electromagnetic valve 73 are different.
[0045]
Further, in the present embodiment, the opening / closing control of the electromagnetic valve 73 is performed using the pressure increase ΔP in the ejector 40 as a parameter. However, the present embodiment is not limited to this, and for example, the rotational speed of the compressor 10, the refrigerant The ejector efficiency ηe is calculated from the temperature, the refrigerant pressure, etc., and the electromagnetic valve 73 is opened when the ejector efficiency ηe becomes a predetermined value or less, and the electromagnetic valve 73 is closed when the ejector efficiency ηe exceeds the predetermined value. Also good. At this time, it goes without saying that the predetermined value of the ejector efficiency ηe when the electromagnetic valve 73 is closed may be different from the predetermined value of the ejector efficiency ηe when the electromagnetic valve 73 is closed.
[0046]
(Fourth embodiment)
This embodiment is a modification of the third embodiment. Specifically, as shown in FIGS. 8 and 9, three types of solenoid valves are provided at the branching or joining portion between the low-pressure side refrigerant passage and the oil return passage 70. 74 is provided so that the electromagnetic valve 82 is opened when the pressure increase amount ΔP at the ejector 40 is less than a predetermined value, and the electromagnetic valve 74 is closed when the pressure increase amount ΔP at the ejector 40 exceeds a predetermined value. Is.
[0047]
8 shows an example in which the electromagnetic valve 74 is arranged at the refrigerant branching portion on the outlet side of the evaporator 30, and FIG. 9 is an example in which the electromagnetic valve 74 is arranged in the refrigerant confluence portion on the outlet side of the ejector 40.
[0048]
(Fifth embodiment)
In the present embodiment, as shown in FIG. 10, piping constituting the oil return passage 70, the ejector 40, the gas-liquid separator 50, the check valve 71, the flow rate control valve 90, and the like (location surrounded by broken lines in FIG. 1). ).
[0049]
In addition, although FIG. 10 applied this embodiment with respect to 1st Embodiment, this embodiment is not limited to this, It applies also to 2nd-4th Embodiment. Needless to say, you can.
[0050]
(Other embodiments)
In the above-described embodiment, carbon dioxide is used as the refrigerant. However, the present invention is not limited to this, and for example, hydrocarbon, chlorofluorocarbon, or the like may be used as the refrigerant.
[0051]
In the above-described embodiment, the high-pressure side refrigerant pressure is set to be equal to or higher than the critical pressure, but the present invention is not limited to this.
[0052]
In the above-described embodiment, the ejector cycle according to the present invention is applied to a vapor compression refrigerator for a showcase that refrigerates and stores food, but the application of the present invention is not limited to this. For example, it can be applied to an air conditioner.
[0053]
The present invention is not limited to the above-described embodiment because the compressor 10 directly sucks the refrigerating machine oil in the evaporator 30 during the oil return mode.
[0054]
Further, at least one of the flow control valve 90 and the internal heat exchanger 80 may be eliminated.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an ejector cycle according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram of an ejector according to an embodiment of the present invention.
FIG. 3 is a ph diagram.
FIG. 4 is an operation explanatory diagram of an ejector cycle according to the first embodiment of the present invention.
FIG. 5 is an operation explanatory diagram of an ejector cycle according to the first embodiment of the present invention.
FIG. 6 is a schematic diagram of an ejector cycle according to a second embodiment of the present invention.
FIG. 7 is a schematic diagram of an ejector cycle according to a third embodiment of the present invention.
FIG. 8 is a schematic diagram of an ejector cycle according to a fourth embodiment of the present invention.
FIG. 9 is a schematic diagram of an ejector cycle according to a fourth embodiment of the present invention.
FIG. 10 is an explanatory diagram showing features of an ejector cycle according to a fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Compressor, 20 ... Radiator, 30 ... Evaporator, 40 ... Ejector,
50 ... Gas-liquid separator, 60 ... Restriction, 70 ... Oil return passage, 71 ... Check valve.

Claims

It is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side,
A high-pressure side heat exchanger (20) that dissipates heat of the high-pressure refrigerant discharged from the compressor (10);
A low pressure side heat exchanger (30) for evaporating the low pressure refrigerant;
It has a nozzle (41) that decompresses and expands high-pressure refrigerant in an isentropic manner, and sucks vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by a high-speed refrigerant flow injected from the nozzle (41). And an ejector (40) for converting the expansion energy into pressure energy to increase the suction pressure of the compressor (10),
The refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, a gas phase refrigerant outlet is connected to the suction side of the compressor (10), and a liquid phase refrigerant outlet is the low pressure side. A gas-liquid separation means (50) connected to the heat exchanger (30);
A refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10);
A valve (71) provided in the refrigerant passage (80) and allowing the refrigerant to flow only to the refrigerant suction side of the compressor (10) from the refrigerant outlet side of the low-pressure side heat exchanger (30). e,
An ejector cycle , wherein a piping member constituting the refrigerant passage (80), the valve (71), and the gas-liquid separator (50) are integrated .

It is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side,
A high-pressure side heat exchanger (20) that dissipates heat of the high-pressure refrigerant discharged from the compressor (10);
A low pressure side heat exchanger (30) for evaporating the low pressure refrigerant;
It has a nozzle (41) that decompresses and expands high-pressure refrigerant in an isentropic manner, and sucks vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by a high-speed refrigerant flow injected from the nozzle (41). And an ejector (40) for converting the expansion energy into pressure energy to increase the suction pressure of the compressor (10),
The refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, a gas phase refrigerant outlet is connected to the suction side of the compressor (10), and a liquid phase refrigerant outlet is the low pressure side. A gas-liquid separation means (50) connected to the heat exchanger (30);
A refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10);
The pressure on the refrigerant outlet side of the low pressure side heat exchanger (30) provided in the refrigerant passage (80) is larger than the pressure on the refrigerant suction side of the compressor (10), and the pressure difference is a predetermined pressure. when a difference above example Bei a valve (71) opening said refrigerant passage (80),
An ejector cycle , wherein a piping member constituting the refrigerant passage (80), the valve (71), and the gas-liquid separator (50) are integrated .

It is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side,
A high-pressure side heat exchanger (20) that dissipates heat of the high-pressure refrigerant discharged from the compressor (10);
A low pressure side heat exchanger (30) for evaporating the low pressure refrigerant;
It has a nozzle (41) that decompresses and expands high-pressure refrigerant in an isentropic manner, and sucks vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by a high-speed refrigerant flow injected from the nozzle (41). And an ejector (40) for converting the expansion energy into pressure energy to increase the suction pressure of the compressor (10),
The refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, a gas phase refrigerant outlet is connected to the suction side of the compressor (10), and a liquid phase refrigerant outlet is the low pressure side. A gas-liquid separation means (50) connected to the heat exchanger (30);
A refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10);
When the pressure on the refrigerant outlet side of the low-pressure side heat exchanger (30) is larger than the pressure on the refrigerant suction side of the compressor (10) and the pressure difference becomes a predetermined pressure difference or more, the refrigerant e Bei the electric valve (73, 74) for allowing the refrigerant to flow through the passage (80),
An ejector cycle , wherein a piping member constituting the refrigerant passage (80), the valves (73, 74), and the gas-liquid separator (50) are integrated .