JP2010101588A

JP2010101588A - Air conditioner

Info

Publication number: JP2010101588A
Application number: JP2008275054A
Authority: JP
Inventors: Koji Shibaike; 幸治芝池; Yoichi Onuma; 洋一大沼; Takahiro Okamoto; 高宏岡本; Tomoyuki Haikawa; 知之配川; Takayuki Setoguchi; 隆之瀬戸口
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2008-10-27
Filing date: 2008-10-27
Publication date: 2010-05-06

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner securing dehumidifying capacity of a heat exchanger functioning as an evaporator and improving performance of reheating dehumidification operation. SOLUTION: The air conditioner 1 includes a refrigerant circuit 10 where a mixed refrigerant of, e.g., HFO-1234yf and HFC-32 are circulated, a four-way selector valve 12 and a control part 20. The four-way selector valve 12 switches the circulating direction of the refrigerant within the refrigerant circuit 10. The refrigerant circuit 10 includes a first heat exchange part 15 functioning as an evaporator during cooling operation and as a condenser during the reheating dehumidification operation and a second heat exchange part 16 functioning as an evaporator during the cooling operation and reheating dehumidification operation. The control part 20 performs switch control of the four-way selector valve 12 to perform a heating cycle during the reheating dehumidification operation, and controls the temperature of the refrigerant to maintain the temperature of the refrigerant made to flow within the second heat exchange part 16 within a predetermined range. COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、空気調和装置に関する。 The present invention relates to an air conditioner.

従来より、空気調和装置には、冷暖房運転だけではなく、再熱除湿運転を行うことが可能なものがある。また、このような空気調和装置に用いられる冷媒としては、クロロフルオロ炭化水素、フルオロ炭化水素、これらの非沸組成物等が知られている。具体的な冷媒としては、Ｒ−１１（トリクロロモノフルオロメタン）、Ｒ−２２（モノクロロジフルオロメタン）、Ｒ５０２（Ｒ−２２＋クロロペンタフルオロエタン）等が、主に利用されている。 Conventionally, some air conditioners are capable of performing not only a cooling / heating operation but also a reheat dehumidifying operation. Moreover, chlorofluorohydrocarbons, fluorohydrocarbons, non-boiling compositions thereof, and the like are known as refrigerants used in such air conditioners. As specific refrigerants, R-11 (trichloromonofluoromethane), R-22 (monochlorodifluoromethane), R502 (R-22 + chloropentafluoroethane) and the like are mainly used.

しかしながら、オゾン層が破壊されると地球上の生態系に悪影響を及ぼすことが指摘され、オゾン層を破壊する危険性の高い冷媒については、使用が制限されるという国際的な取り決めがなされている。 However, it has been pointed out that the destruction of the ozone layer has a negative impact on the global ecosystem, and there is an international agreement that the use of refrigerants with high risk of destroying the ozone layer is restricted. .

これに対し、例えば特許文献１に示されるように、仮に空気調和装置から大気中に漏れだしたとしても、オゾン層を破壊する危険性が極めて低い冷媒が提案されている。具体的に、特許文献１には、塩素原子及び臭素原子を含まない冷媒が開示されている。
特開平４−１１０３８８号公報 On the other hand, as disclosed in Patent Document 1, for example, a refrigerant has been proposed that has a very low risk of destroying the ozone layer even if it leaks from the air conditioner into the atmosphere. Specifically, Patent Document 1 discloses a refrigerant that does not contain chlorine atoms and bromine atoms.
JP-A-4-110388

ところで、特許文献１に記載された冷媒以外に、オゾン層を破壊する危険性が極めて低い冷媒として、分子式：Ｃ₃Ｈ_mＦ_n（但し、ｍ＝１〜５、ｎ＝１〜５、かつ、ｍ＋ｎ＝６）で示され、かつ、分子構造中に二重結合を１個有する冷媒を含む混合冷媒がある。近年では、この混合冷媒を用いた空気調和装置の開発が行われている。しかしながら、この混合冷媒は、同一圧力において乾き度が大きいと温度が上昇するという特性を有している。そのため、蒸発器内に流入する時の冷媒の温度と蒸発器から流出する時の冷媒の温度との差が比較的大きくなる場合がある。すると、この混合冷媒を用いた空気調和装置において、再熱除湿運転が行われた場合、蒸発器として機能する熱交換器内を流れる冷媒の温度が上昇してしまい、該熱交換器の除湿能力を確保することが困難となってしまう。 By the way, in addition to the refrigerant described in Patent Document 1, as a refrigerant having a very low risk of destroying the ozone layer, molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and M + n = 6) and a mixed refrigerant containing a refrigerant having one double bond in the molecular structure. In recent years, an air conditioner using this mixed refrigerant has been developed. However, this mixed refrigerant has a characteristic that the temperature rises when the dryness is large at the same pressure. Therefore, the difference between the temperature of the refrigerant when flowing into the evaporator and the temperature of the refrigerant when flowing out of the evaporator may be relatively large. Then, in the air conditioner using this mixed refrigerant, when the reheat dehumidifying operation is performed, the temperature of the refrigerant flowing in the heat exchanger functioning as an evaporator rises, and the dehumidifying capacity of the heat exchanger It will be difficult to ensure.

そこで、本発明は、蒸発器として機能する熱交換器の除湿能力を確保することができ、再熱除湿運転の性能を向上させることができる空気調和装置の提供を目的とする。 Then, this invention aims at provision of the air conditioning apparatus which can ensure the dehumidification capability of the heat exchanger which functions as an evaporator, and can improve the performance of a reheat dehumidification driving | operation.

発明１に係る空気調和装置は、冷媒回路と、切り換え機構と、制御部とを備える。冷媒回路は、圧縮機、熱源側熱交換器、第１膨張機構及び利用側熱交換器を含む。切り換え機構は、冷媒回路内の冷媒の循環方向を切り換える。制御部は、冷房運転時には冷房サイクルが行われ、暖房運転時には暖房サイクルが行われるように、切り換え機構の循環方向の切り換え制御を行う。利用側熱交換器は、第１熱交換部及び第２熱交換部を有する。第１熱交換部は、冷房運転時に蒸発器として機能し、再熱除湿運転時に凝縮器として機能する。第２熱交換部は、冷房運転時及び再熱除湿運転時に蒸発器として機能する。冷媒は、分子式：Ｃ₃Ｈ_mＦ_n（但し、ｍ＝１〜５，ｎ＝１〜５且つｍ＋ｎ＝６）で示され、且つ分子構造中に二重結合を１個有する冷媒を含む混合冷媒である。そして、制御部は、再熱除湿運転時には暖房サイクルが行われるように、切り換え機構の循環方向の切り換え制御を行う。更に、制御部は、第２熱交換部内を流れる冷媒の温度が所定範囲内に保たれるように、冷媒の温度を制御する。 The air conditioning apparatus according to the first aspect includes a refrigerant circuit, a switching mechanism, and a control unit. The refrigerant circuit includes a compressor, a heat source side heat exchanger, a first expansion mechanism, and a use side heat exchanger. The switching mechanism switches the circulation direction of the refrigerant in the refrigerant circuit. The control unit performs switching control of the circulation direction of the switching mechanism so that the cooling cycle is performed during the cooling operation and the heating cycle is performed during the heating operation. The usage-side heat exchanger has a first heat exchange part and a second heat exchange part. The first heat exchange unit functions as an evaporator during the cooling operation and functions as a condenser during the reheat dehumidifying operation. The second heat exchange unit functions as an evaporator during the cooling operation and the reheat dehumidifying operation. The refrigerant is a mixture containing a refrigerant represented by a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6) and having one double bond in the molecular structure. Refrigerant. And a control part performs switching control of the circulation direction of a switching mechanism so that a heating cycle may be performed at the time of a reheat dehumidification operation. Furthermore, the control unit controls the temperature of the refrigerant so that the temperature of the refrigerant flowing in the second heat exchange unit is maintained within a predetermined range.

この空気調和装置によると、再熱除湿運転時には、暖房サイクルが行われると共に、蒸発器として機能する第２熱交換部内を流れる冷媒の温度は所定範囲内に保たれる。ここで、所定範囲が、第２熱交換部が除湿を行うことができる温度範囲であるとすると、第２熱交換部の表面温度は除湿できる温度以下に保たれるため、再熱除湿運転の性能を向上させることができる。 According to this air conditioner, during the reheat dehumidification operation, a heating cycle is performed, and the temperature of the refrigerant flowing in the second heat exchange unit functioning as an evaporator is kept within a predetermined range. Here, assuming that the predetermined range is a temperature range in which the second heat exchange unit can perform dehumidification, the surface temperature of the second heat exchange unit is kept below a temperature at which dehumidification can be performed. Performance can be improved.

発明２に係る空気調和装置は、発明１に係る空気調和装置であって、冷媒回路は、第２膨張機構を更に含む。第２膨張機構は、第１熱交換部及び第２熱交換部の間に設けられる。そして、制御部は、第２膨張機構の開度を調整することで、冷媒の温度を制御する。 An air conditioner according to a second aspect is the air conditioner according to the first aspect, wherein the refrigerant circuit further includes a second expansion mechanism. The second expansion mechanism is provided between the first heat exchange unit and the second heat exchange unit. And a control part controls the temperature of a refrigerant | coolant by adjusting the opening degree of a 2nd expansion mechanism.

この空気調和装置によると、第１熱交換部と第２熱交換部との間の第２膨張機構の開度が調整されることにより、第２熱交換部内の冷媒の温度が所定範囲内に保たれるようになる。 According to this air conditioner, the temperature of the refrigerant in the second heat exchange unit falls within a predetermined range by adjusting the opening of the second expansion mechanism between the first heat exchange unit and the second heat exchange unit. Will be kept.

発明３に係る空気調和装置は、発明２に係る空気調和装置であって、制御部は、再熱除湿運転時、第２膨張機構を流出した冷媒が第２熱交換部に流入する際の、第２熱交換部の流入口付近の温度が、水の氷結する温度以上となるように、第２膨張機構の開度を調整する。 An air conditioner according to a third aspect of the present invention is the air conditioner according to the second aspect of the present invention, wherein the control unit is configured so that the refrigerant that has flowed out of the second expansion mechanism flows into the second heat exchange unit during the reheat dehumidification operation. The opening degree of the second expansion mechanism is adjusted so that the temperature in the vicinity of the inlet of the second heat exchange unit is equal to or higher than the temperature at which water freezes.

この空気調和装置によると、再熱除湿運転時には、第２熱交換部の流入口付近の温度（即ち、第２交換部の流入口の周囲温度）が水の氷結する温度以上となるように、第２膨張機構の開度を調節することによって冷媒の温度が制御されるため、第２熱交換部の流入口付近が着霜してしまうのを防ぐことができる。 According to this air conditioner, during the reheat dehumidifying operation, the temperature in the vicinity of the inlet of the second heat exchange unit (that is, the ambient temperature of the inlet of the second exchange unit) is equal to or higher than the temperature at which water freezes. Since the temperature of the refrigerant is controlled by adjusting the opening of the second expansion mechanism, it is possible to prevent the vicinity of the inlet of the second heat exchange unit from frosting.

発明４に係る空気調和装置は、発明１〜３のいずれかに係る空気調和装置であって、冷媒は、更にジフルオロメタンを含む混合冷媒である。 An air conditioner according to a fourth aspect is the air conditioner according to any one of the first to third aspects, wherein the refrigerant is a mixed refrigerant further containing difluoromethane.

冷媒がジフルオロメタン（即ち、ＨＦＣ―３２）を含む混合冷媒である場合、同一圧力において乾き度が比較的大きいと温度が上昇するといった特性が顕著となる。しかし、この空気調和装置は、ＨＦＣ−３２を含む混合冷媒を採用しても、再熱除湿運転時には暖房サイクルを行い、かつ蒸発器として機能する第２熱交換部内を流れる冷媒の温度を所定範囲内に保つため、再熱除湿運転の性能を向上させることが可能となる。 When the refrigerant is a mixed refrigerant containing difluoromethane (that is, HFC-32), the characteristic that the temperature rises when the dryness is relatively large at the same pressure becomes remarkable. However, even if this air-conditioning apparatus employs a mixed refrigerant containing HFC-32, the temperature of the refrigerant flowing in the second heat exchange section that performs the heating cycle and functions as an evaporator during the reheat dehumidification operation is within a predetermined range. Therefore, the performance of the reheat dehumidification operation can be improved.

発明５に係る空気調和装置は、発明１〜４のいずれかに係る空気調和装置であって、所定範囲は、第２熱交換部の表面温度が露点温度以下となる範囲である。 The air conditioner according to a fifth aspect of the present invention is the air conditioner according to any of the first to fourth aspects of the present invention, wherein the predetermined range is a range in which the surface temperature of the second heat exchanging section is equal to or lower than the dew point temperature.

この空気調和装置は、再熱除湿運転時、第２熱交換部の表面温度が露点温度以下となるように冷媒の温度を制御するため、第２熱交換部は、確実に除湿できるようになる。 Since the air conditioner controls the temperature of the refrigerant so that the surface temperature of the second heat exchange unit is equal to or lower than the dew point temperature during the reheat dehumidification operation, the second heat exchange unit can reliably dehumidify. .

発明６に係る空気調和装置は、発明１〜５のいずれかに係る空気調和装置であって、再熱除湿運転において、第２熱交換部における冷媒の流入口に設けられた第１パスの数は、冷媒の流出口に設けられた第２パスの数よりも少ない。 An air conditioner according to a sixth aspect of the present invention is the air conditioner according to any of the first to fifth aspects, wherein the number of first passes provided at the refrigerant inlet in the second heat exchange section in the reheat dehumidifying operation. Is less than the number of second passes provided at the refrigerant outlet.

この空気調和装置によると、再熱除湿運転時における第２熱交換部の流入口側の第１パスは、第２熱交換部の流出口側の第２パスよりも本数が少ないため、再熱除湿運転時に蒸発器として機能する第２熱交換部の流出口側における冷媒の圧力損失を積極的につけることができる。 According to this air conditioner, the number of first passes on the inlet side of the second heat exchange unit during the reheat dehumidification operation is smaller than the number of second passes on the outlet side of the second heat exchange unit. It is possible to positively apply a refrigerant pressure loss on the outlet side of the second heat exchange unit that functions as an evaporator during the dehumidifying operation.

発明７に係る空気調和装置は、発明１〜６のいずれかに係る空気調和装置であって、再熱除湿運転において、第２熱交換部における前記冷媒の流入口に設けられた第３パスの径は、冷媒の流出口に設けられた第４パスの径よりも小さい。 An air conditioner according to a seventh aspect of the present invention is the air conditioner according to any of the first to sixth aspects of the present invention, wherein, in the reheat dehumidifying operation, the third path provided at the refrigerant inlet in the second heat exchange unit. The diameter is smaller than the diameter of the fourth path provided at the refrigerant outlet.

この空気調和装置によると、再熱除湿運転時における第２熱交換部の流入口側の第１パスは、第２熱交換部の流出口側の第２パスよりも径が小さいため、再熱除湿運転時に蒸発器として機能する第２熱交換部の流出口側における冷媒の圧力損失を積極的につけることができる。 According to this air conditioner, the first path on the inlet side of the second heat exchange unit during the reheat dehumidifying operation has a smaller diameter than the second path on the outlet side of the second heat exchange unit. It is possible to positively apply a refrigerant pressure loss on the outlet side of the second heat exchange unit that functions as an evaporator during the dehumidifying operation.

発明１に係る空気調和装置によると、再熱除湿運転の性能を向上させることが可能となる。 With the air conditioner according to the first aspect, it is possible to improve the performance of the reheat dehumidifying operation.

発明２に係る空気調和装置によると、第１熱交換部と第２熱交換部との間の第２膨張機構の開度が調整されることにより、第２熱交換部内の冷媒の温度が所定範囲内に保たれるようになる。 According to the air conditioner pertaining to the second aspect of the present invention, the temperature of the refrigerant in the second heat exchange unit is predetermined by adjusting the opening of the second expansion mechanism between the first heat exchange unit and the second heat exchange unit. Will be kept within range.

発明３に係る空気調和装置によると、第２熱交換部の流入口付近が着霜してしまうのを防ぐことができる。 According to the air conditioner pertaining to the third aspect of the present invention, it is possible to prevent the vicinity of the inlet of the second heat exchange part from frosting.

発明４に係る空気調和装置によると、ＨＦＣ−３２を含む混合冷媒を採用しても、再熱除湿運転時には暖房サイクルを行い、かつ蒸発器として機能する第２熱交換部内を流れる冷媒の温度を所定範囲内に保つため、再熱除湿運転の性能を向上させることが可能となる。 According to the air conditioner pertaining to the fourth aspect of the present invention, even if a mixed refrigerant containing HFC-32 is employed, the temperature of the refrigerant flowing in the second heat exchange section that performs the heating cycle and functions as an evaporator during the reheat dehumidification operation is adjusted. Since it keeps in the predetermined range, it becomes possible to improve the performance of the reheat dehumidification operation.

発明５に係る空気調和装置によると、第２熱交換部は、確実に除湿できるようになる。 According to the air conditioner pertaining to the fifth aspect of the invention, the second heat exchange unit can reliably dehumidify.

発明６及び７に係る空気調和装置によると、再熱除湿運転時に蒸発器として機能する第２熱交換部の流出口側における冷媒の圧力損失を積極的につけることができる。 According to the air conditioner according to the sixth and seventh aspects of the present invention, it is possible to positively apply a refrigerant pressure loss on the outlet side of the second heat exchange unit that functions as an evaporator during the reheat dehumidification operation.

以下、本実施形態に係る空気調和装置について、図面を用いて詳細に説明する。 Hereinafter, the air conditioning apparatus according to the present embodiment will be described in detail with reference to the drawings.

（１）構成
図１は、本発明の一実施形態に係る空気調和装置１の外観図である。本実施形態に係る空気調和装置１は、図１に示すように、室外機２と室内機３とに分かれて構成されたセパレートタイプの空気調和装置であって、室外機２及び室内機３は、冷媒配管４ａ，４ｂによって接続されている。このような空気調和装置１は、冷房運転、暖房運転及び再熱除湿運転を行うことができる。尚、空気調和装置１がどの種類の運転を行うかは、リモートコントローラＲｅを介してユーザにより指示される。 (1) Configuration FIG. 1 is an external view of an air conditioner 1 according to an embodiment of the present invention. As shown in FIG. 1, the air conditioner 1 according to the present embodiment is a separate type air conditioner configured to be divided into an outdoor unit 2 and an indoor unit 3, and the outdoor unit 2 and the indoor unit 3 are The refrigerant pipes 4a and 4b are connected. Such an air conditioner 1 can perform a cooling operation, a heating operation, and a reheat dehumidifying operation. In addition, what kind of operation the air conditioner 1 performs is instructed by the user via the remote controller Re.

そして、空気調和装置１は、図２に示すように、主として、冷媒回路１０と、冷媒回路１０内を循環する冷媒と、冷媒回路１０内の冷媒の循環方向を切り換える四路切換弁１２（切り換え機構に相当）と、四路切換弁１２の循環方向の切り換え制御等を行う制御部２０とを備える。 As shown in FIG. 2, the air conditioner 1 mainly includes a refrigerant circuit 10, a refrigerant that circulates in the refrigerant circuit 10, and a four-way switching valve 12 that switches a circulation direction of the refrigerant in the refrigerant circuit 10 (switching). And a control unit 20 that performs switching control of the circulation direction of the four-way switching valve 12 and the like.

〔冷媒〕
ここで、本実施形態において用いられる冷媒について説明する。冷媒としては、Ｃ₃Ｈ_mＦ_n（但し、ｍ＝１〜５，ｎ＝１〜５且つｍ＋ｎ＝６）の分子式で示され、且つ分子構造中に二重結合を１個有する冷媒を含む混合冷媒が用いられる。つまり、冷媒には、蒸発中に温度が変化する度合いが比較的大きい特性を有する冷媒を用いる。尚、分子式：Ｃ₃Ｈ_mＦ_nで示される冷媒の例としては、ＨＦＯ−１２２５ｙｅ（１，２，３，３，３−ペンタフルオロ−１−プロペン、化学式：ＣＦ₃−ＣＦ＝ＣＨＦ）、ＨＦＯ−１２３４ｚｅ（１，３，３，３−テトラフルオロ−１−プロペン、化学式：ＣＦ₃−ＣＨ＝ＣＨＦ）、ＨＦＯ−１２３４ｙｅ（１，２，３，３−テトラフルオロ−１−プロペン、化学式：ＣＨＦ₂−ＣＦ＝ＣＨＦ）、ＨＦＯ−１２４３ｚｆ（３，３，３−トリフルオロ−１−プロペン、化学式：ＣＦ₃−ＣＨ＝ＣＨ₂）、１，２，２−トリフルオロ−１−プロペン（化学式：ＣＨ₃−ＣＦ＝ＣＦ₂）、２−フルオロ−１−プロペン（化学式：ＣＨ₃−ＣＦ＝ＣＨ₂）等が挙げられる。 [Refrigerant]
Here, the refrigerant used in the present embodiment will be described. The refrigerant includes a refrigerant represented by a molecular formula of C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6) and having one double bond in the molecular structure. A mixed refrigerant is used. That is, as the refrigerant, a refrigerant having a characteristic that the degree of change in temperature during evaporation is relatively large is used. Examples of the refrigerant represented by the molecular formula: C ₃ H _m F _n include HFO-1225ye (1,2,3,3,3-pentafluoro-1-propene, chemical formula: CF ₃ —CF═CHF), HFO-1234ze (1,3,3,3-tetrafluoro-1-propene, chemical formula: CF ₃ —CH═CHF), HFO-1234ye (1,2,3,3-tetrafluoro-1-propene, chemical formula: CHF ₂ —CF═CHF), HFO-1243zf (3,3,3-trifluoro-1-propene, chemical formula: CF ₃ —CH═CH ₂ ), 1,2,2-trifluoro-1-propene (chemical formula _{_{: CH 3 -CF = CF 2)}} , 2- fluoro-1-propene (chemical formula: CH ₃ -CF = CH _2), and the like.

本発明において用いられる混合冷媒としては、上述した単一冷媒を含む混合冷媒が挙げられる。具体的には、ＨＦＯ−１２３４ｙｆ（２，３，３，３−テトラフルオロ−１−プロペン）とＨＦＣ−３２（ジフルオロメタン）との混合冷媒や、ＨＦＯ−１２３４ｙｆ（２，３，３，３−テトラフルオロ−１−プロペン）とＨＦＣ−１２５（ペンタフルオロエタン）との混合冷媒等が挙げられるが、本実施形態では、ＨＦＯ−１２３４ｙｆとＨＦＣ−３２との混合冷媒を用いる場合を例に取る。ここで、この混合冷媒の組成としては、ＨＦＯ−１２３４ｙｆの割合が７０質量％以上９４質量％以下でＨＦＣ−３２の割合が６質量％以上３０質量％以下がよく、好ましくは、ＨＦＯ−１２３４ｙｆの割合が７７質量％以上８７質量％以下でＨＦＣ−３２の割合が１３質量％以上２３質量％以下がよく、さらに好ましくは、ＨＦＯ−１２３４ｙｆの割合が７７質量％以上７９質量％以下でＨＦＣ−３２の割合が２１質量％以上２３質量％以下（例えば、７８質量％のＨＦＯ−１２３４ｙｆと２２質量％のＨＦＣ−３２との混合冷媒）がよい。 Examples of the mixed refrigerant used in the present invention include the mixed refrigerant including the single refrigerant described above. Specifically, a mixed refrigerant of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) and HFC-32 (difluoromethane), or HFO-1234yf (2,3,3,3- Examples include a mixed refrigerant of tetrafluoro-1-propene) and HFC-125 (pentafluoroethane). In this embodiment, a case of using a mixed refrigerant of HFO-1234yf and HFC-32 is taken as an example. Here, as a composition of this mixed refrigerant, the ratio of HFO-1234yf is 70% by mass to 94% by mass and the ratio of HFC-32 is 6% by mass to 30% by mass, preferably HFO-1234yf The proportion is 77% by mass or more and 87% by mass or less, and the proportion of HFC-32 is preferably 13% by mass or more and 23% by mass or less. More preferably, the proportion of HFO-1234yf is 77% by mass or more and 79% by mass or less. Is preferably 21% by mass or more and 23% by mass or less (for example, a mixed refrigerant of 78% by mass of HFO-1234yf and 22% by mass of HFC-32).

〔冷媒回路及び四路切換弁〕
次に、本実施形態に係る冷媒回路１０及び四路切換弁１２について、主に図２〜図４を用いて説明する。冷媒回路１０は、室外機２に設けられた熱源側回路１０ａと、室内機３に設けられた利用側回路１０ｂとを有する。熱源側回路１０ａには、主として、圧縮機１１、四路切換弁１２、室外熱交換器１３（熱源側熱交換器に相当）及び室外側膨張弁１４（第１膨張機構に相当）が接続されている。利用側回路１０ｂには、第１熱交換部１５及び第２熱交換部１６を含む室内熱交換器（利用側熱交換器に相当）、及び室内側膨張弁１７（第２膨張機構に相当）が接続されている。 [Refrigerant circuit and four-way selector valve]
Next, the refrigerant circuit 10 and the four-way switching valve 12 according to the present embodiment will be described mainly with reference to FIGS. The refrigerant circuit 10 includes a heat source side circuit 10 a provided in the outdoor unit 2 and a use side circuit 10 b provided in the indoor unit 3. A compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13 (corresponding to a heat source side heat exchanger), and an outdoor expansion valve 14 (corresponding to a first expansion mechanism) are mainly connected to the heat source side circuit 10a. ing. The use side circuit 10b includes an indoor heat exchanger (corresponding to a use side heat exchanger) including a first heat exchange unit 15 and a second heat exchange unit 16, and an indoor side expansion valve 17 (corresponding to a second expansion mechanism). Is connected.

圧縮機１１は、吸入側が四路切換弁１２の第１ポートａ１に接続され、吐出側が四路切換弁１２の第２ポートａ２に接続されている。圧縮機１１は、可変容量型のいわゆる全密閉型に構成されており、吸入側から吸入した冷媒を圧縮して吐出側へ吐出する。 The compressor 11 has a suction side connected to the first port a 1 of the four-way switching valve 12 and a discharge side connected to the second port a 2 of the four-way switching valve 12. The compressor 11 is configured as a so-called fully-sealed variable capacity type, and compresses the refrigerant sucked from the suction side and discharges it to the discharge side.

四路切換弁１２は、第３ポートａ３が室外熱交換器１３の一端と接続され、第４ポートａ４が室内熱交換器における第１熱交換部１５の一端に接続されている。そして、四路切換弁１２は、第１ポートａ１と第４ポートａ４とが内部で連結すると共に第２ポートａ２と第３ポートａ３とが内部で連結する第１状態と（図２）、第１ポートａ１と第３ポートａ３とが内部で連結すると共に第２ポートａ２と第４ポートａ４とが内部で連結する第２状態（図３，図４）とを採り得る。尚、四路切換弁１２が第１状態及び第２状態のいずれを採るかは、後述する制御部２０により決定される。 In the four-way switching valve 12, the third port a3 is connected to one end of the outdoor heat exchanger 13, and the fourth port a4 is connected to one end of the first heat exchange unit 15 in the indoor heat exchanger. The four-way switching valve 12 has a first state in which the first port a1 and the fourth port a4 are internally connected and the second port a2 and the third port a3 are internally connected (FIG. 2), A second state (FIGS. 3 and 4) in which the first port a1 and the third port a3 are internally connected and the second port a2 and the fourth port a4 are internally connected may be employed. Whether the four-way switching valve 12 takes the first state or the second state is determined by the control unit 20 described later.

室外熱交換器１３は、一端が四路切換弁１２の第３ポートａ３に接続されており、他端が室外側膨張弁１４に接続されている。このような室外熱交換器１３は、図示してはいないが、一方向に積層された複数のフィンと、該フィンを貫通する複数の伝熱管とにより構成されており、各伝熱管の端部は、冷媒回路１０における配管（冷媒配管４ａまたは４ｂ）に接続されている。室外熱交換器１３は、室外機２内部に設けられた室外ファン（図示せず）によって取り込まれた室外空気と、冷媒回路１０内を循環する冷媒との間で熱交換を行う。このようにして熱交換が行われた後の空気は、室外に排出される。 One end of the outdoor heat exchanger 13 is connected to the third port a 3 of the four-way switching valve 12, and the other end is connected to the outdoor expansion valve 14. Although not shown, such an outdoor heat exchanger 13 includes a plurality of fins stacked in one direction and a plurality of heat transfer tubes penetrating the fins, and ends of the heat transfer tubes. Is connected to a pipe (refrigerant pipe 4a or 4b) in the refrigerant circuit 10. The outdoor heat exchanger 13 performs heat exchange between outdoor air taken in by an outdoor fan (not shown) provided inside the outdoor unit 2 and refrigerant circulating in the refrigerant circuit 10. The air after the heat exchange is performed in this way is discharged to the outside.

室外側膨張弁１４は、室外熱交換器１３と室内熱交換器における第２熱交換部１６との間に接続されている。室外側膨張弁１４は、流入してきた冷媒を減圧させ、減圧された冷媒を流出する。 The outdoor expansion valve 14 is connected between the outdoor heat exchanger 13 and the second heat exchange unit 16 in the indoor heat exchanger. The outdoor expansion valve 14 decompresses the refrigerant that has flowed in, and flows out the decompressed refrigerant.

室内熱交換器は、室内機３内部に設けられた室内ファン（図示せず）によって取り込まれた室内空気と、冷媒回路１０内を循環する冷媒との間で熱交換を行う。具体的に、室内熱交換器の第１熱交換部１５は、一端が四路切換弁１２の第４ポートａ４に接続されている。第１熱交換部１５は、冷房運転時には蒸発器として機能し（図２）、暖房運転時及び再熱除湿運転時には、凝縮器として機能する（図３，図４）。第２熱交換部１６は、一端が室外側膨張弁１４に接続されている。第２熱交換部１６は、冷房運転時及び再熱除湿運転時には、蒸発器として機能し、暖房運転時には、凝縮器として機能する。このような第１及び第２熱交換部１５，１６によって熱交換が行われた後の空気は、室内ファンによって室内に供給されるようになる。 The indoor heat exchanger performs heat exchange between indoor air taken in by an indoor fan (not shown) provided inside the indoor unit 3 and refrigerant circulating in the refrigerant circuit 10. Specifically, one end of the first heat exchange unit 15 of the indoor heat exchanger is connected to the fourth port a4 of the four-way switching valve 12. The first heat exchange unit 15 functions as an evaporator during the cooling operation (FIG. 2), and functions as a condenser during the heating operation and the reheat dehumidifying operation (FIGS. 3 and 4). One end of the second heat exchange unit 16 is connected to the outdoor expansion valve 14. The second heat exchange unit 16 functions as an evaporator during the cooling operation and the reheat dehumidification operation, and functions as a condenser during the heating operation. The air after the heat exchange is performed by the first and second heat exchange units 15 and 16 is supplied to the room by the indoor fan.

尚、第１熱交換部１５及び第２熱交換部１６それぞれは、室外熱交換器１３と同様、一方向に積層された複数のフィンと、該フィンを貫通する複数の伝熱管とにより構成されており、各伝熱管の端部は、冷媒回路１０における配管（具体的には、冷媒配管４ａまたは４ｂ）に接続されている。従って、第１及び第２熱交換部１５，１６と配管との間には、複数のパスが形成されているが、本実施形態では、再熱除湿運転の際、第２熱交換部１６における冷媒の流入口（図４の点ｃ３側）に設けられた第１パスの本数が、冷媒の流出口（図４の点ｃ４側）に設けられた第２パスの本数よりも少なくなるように、パス取りがなされている。つまり、第２熱交換部１６の流入口側における第１パスの本数よりも、流出口側における第２パスの本数の方が多い。これにより、再熱除湿運転時に蒸発器として機能する第２熱交換部１６の流出口側（つまり、図４の点ｃ４側）における冷媒の圧力損失を積極的につけることができる。 Each of the first heat exchange unit 15 and the second heat exchange unit 16 is configured by a plurality of fins stacked in one direction and a plurality of heat transfer tubes penetrating the fins, like the outdoor heat exchanger 13. The end of each heat transfer tube is connected to a pipe in the refrigerant circuit 10 (specifically, the refrigerant pipe 4a or 4b). Therefore, a plurality of paths are formed between the first and second heat exchanging units 15 and 16 and the pipe, but in the present embodiment, in the second heat exchanging unit 16 during the reheat dehumidifying operation. The number of first paths provided at the refrigerant inlet (point c3 side in FIG. 4) is smaller than the number of second paths provided at the refrigerant outlet (point c4 side in FIG. 4). A pass has been taken. That is, the number of second paths on the outlet side is greater than the number of first paths on the inlet side of the second heat exchange unit 16. Thereby, the pressure loss of the refrigerant | coolant in the outflow port side (namely, the point c4 side of FIG. 4) of the 2nd heat exchange part 16 which functions as an evaporator at the time of a reheat dehumidification operation can be positively attached.

室内側膨張弁１７は、第１熱交換部１５と第２熱交換部１６との間に設けられており、室外側膨張弁１４と同様、流入してきた冷媒を減圧して流出する役割を担う。 The indoor side expansion valve 17 is provided between the first heat exchange unit 15 and the second heat exchange unit 16, and, like the outdoor side expansion valve 14, plays a role of depressurizing and flowing out the refrigerant that has flowed in. .

このような冷媒回路１０及び四路切換弁１２によると、冷房運転時には、四路切換弁１２が第１状態を採り（図２）、冷媒が図２の矢印の方向に循環することで、冷房サイクルが行われるようになる。この時、室外熱交換器１３は凝縮器、第１熱交換部１５及び第２熱交換部１６は共に蒸発器として機能し、室内には冷たい空気が供給されるようになる。また、暖房運転時には、四路切換弁１２が第２状態を採り（図３）、冷媒が図３の矢印の方向に循環することで、暖房サイクルが行われるようになる。この時、室外熱交換器１３は蒸発器、第１熱交換部１５及び第２熱交換部１６は共に凝縮器として機能し、室内には暖かい空気が供給されるようになる。更に、再熱除湿運転時には、四路切換弁１２が第２状態を採り（図４）、冷媒が図４の矢印の方向に循環することで、暖房サイクルと同様のサイクルが再熱除湿サイクルとして行われるようになる。この時、室外熱交換器１３は蒸発器、第１熱交換部１５は凝縮器、第２熱交換部１６は蒸発器として機能し、室内には除湿されると共に温められた空気が供給されるようになる。 According to such a refrigerant circuit 10 and the four-way switching valve 12, during the cooling operation, the four-way switching valve 12 takes the first state (FIG. 2), and the refrigerant circulates in the direction of the arrow in FIG. The cycle will be performed. At this time, the outdoor heat exchanger 13 functions as a condenser, and the first heat exchange unit 15 and the second heat exchange unit 16 both function as an evaporator, and cold air is supplied into the room. Further, during the heating operation, the four-way switching valve 12 takes the second state (FIG. 3), and the refrigerant circulates in the direction of the arrow in FIG. At this time, the outdoor heat exchanger 13 functions as an evaporator, and the first heat exchange unit 15 and the second heat exchange unit 16 both function as a condenser, and warm air is supplied into the room. Furthermore, during the reheat dehumidification operation, the four-way switching valve 12 takes the second state (FIG. 4), and the refrigerant circulates in the direction of the arrow in FIG. To be done. At this time, the outdoor heat exchanger 13 functions as an evaporator, the first heat exchange unit 15 functions as a condenser, and the second heat exchange unit 16 functions as an evaporator. The room is supplied with dehumidified and warmed air. It becomes like this.

〔制御部〕
制御部２０は、主として、ＣＰＵ及びメモリからなるマイクロコンピュータで構成されている。制御部２０は、冷媒回路１０を構成する各種機器の駆動部（具体的には、圧縮機１１の圧縮機用モータ、四路切換弁１２の駆動用モータ、室外側膨張弁１４の駆動部、室内側膨張弁１７の駆動部等）と接続されており、接続された各駆動部の駆動制御を行う。具体的には、制御部２０は、圧縮機１１の起動及び容量制御や、各膨張弁１４，１７の開度調整、空気調和装置１の運転種類に基づく四路切換弁１２の循環方向の切換制御等を行う。例えば、制御部２０は、冷房運転時には四路切換弁１２が第１状態を採ることで冷房サイクルが行われ、暖房運転時には四路切換弁１２が第２状態を採ることで暖房サイクルが行われるように、四路切換弁１２の切換制御を行う。特に、本実施形態に係る制御部２０は、再熱除湿運転時には、本実施形態に係る再熱除湿サイクル（図４）、即ち暖房サイクル（図３）と同様のサイクルが行われるように、四路切換弁１２の第２ポートａ２及び第４ポートａ４、第１ポートａ１及び第３ポートａ３それぞれを接続させる切換制御を行う。つまり、制御部２０は、再熱除湿運転時には、四路切換弁１２が第２状態を採るように、四路切換弁１２の切換制御を行う。 (Control part)
The control unit 20 is mainly composed of a microcomputer including a CPU and a memory. The control unit 20 is a drive unit of various devices constituting the refrigerant circuit 10 (specifically, a compressor motor of the compressor 11, a drive motor of the four-way switching valve 12, a drive unit of the outdoor expansion valve 14, And drive control of each connected drive unit. Specifically, the control unit 20 switches the direction of circulation of the four-way switching valve 12 based on the start-up and capacity control of the compressor 11, the opening adjustment of the expansion valves 14 and 17, and the operation type of the air conditioner 1. Control and so on. For example, the control unit 20 performs the cooling cycle when the four-way switching valve 12 takes the first state during the cooling operation, and performs the heating cycle when the four-way switching valve 12 takes the second state during the heating operation. Thus, the switching control of the four-way switching valve 12 is performed. In particular, the control unit 20 according to the present embodiment performs four cycles so that a reheat dehumidification cycle (FIG. 4) according to the present embodiment, that is, a cycle similar to the heating cycle (FIG. 3) is performed during the reheat dehumidification operation. Switching control for connecting the second port a2 and the fourth port a4, the first port a1 and the third port a3 of the path switching valve 12 is performed. That is, the control unit 20 performs switching control of the four-way switching valve 12 so that the four-way switching valve 12 takes the second state during the reheat dehumidifying operation.

更に、制御部２０は、再熱除湿運転時には、室内側膨張弁１７の開度を調整することで冷媒の温度を制御する。具体的には、制御部２０は、第２熱交換部１６内を流れる冷媒の温度が所定範囲内に保たれるように、室内側膨張弁１７の開度を調整する。ここで、所定範囲としては、図５に示すように、第２熱交換部１６の表面温度が露点温度以下となるような温度が挙げられる。つまり、制御部２０は、再熱除湿運転時、第２熱交換部１６内を流れる冷媒が、第２熱交換部１６の表面温度が露点温度以下を保つように、室内側膨張弁１７の開度を調整する。再熱除湿運転時、蒸発器として機能する第２熱交換部１６には、液化した冷媒が流入する。この冷媒は、第２熱交換部１６に接触する空気から熱を受け取り、ガス化して第２熱交換部１６から流出する。これにより、第２熱交換部１６では、空気の除湿が行われる。しかし、第２熱交換部１６内の冷媒の温度が高く、既にガス化した冷媒が多いと、冷媒が空気から受け取ることができる熱量が小さくなるため、第２熱交換部１６自体の除湿能力が低下してしまう。特に、本実施形態では、蒸発中の温度が変化する度合いが比較的大きい特性を有する混合冷媒（ＨＦＯ−１２３４ｙｆとＨＦＣ−３２との混合冷媒）を用いているため、第２熱交換部１６自体の除湿能力が低下する恐れが高い。しかし、本実施形態に係る制御部２０は、室内側膨張弁１７の開度を調整することにより、第２熱交換部１６の表面温度が露点温度以下を保つように冷媒の温度を制御するため、上記混合冷媒を用いたとしても、第２熱交換部１６の除湿能力が確保されるようになる。尚、図５では、第２熱交換部１６の表面温度が露点温度である時の冷媒の温度を、“温度Ａ”として表している。温度Ａとしては、露点温度が挙げられる。つまりこの場合、冷媒が露点温度以下となる範囲が、所定範囲となる。 Furthermore, the control part 20 controls the temperature of a refrigerant | coolant by adjusting the opening degree of the indoor side expansion valve 17 at the time of a reheat dehumidification driving | operation. Specifically, the control unit 20 adjusts the opening degree of the indoor expansion valve 17 so that the temperature of the refrigerant flowing in the second heat exchange unit 16 is maintained within a predetermined range. Here, as the predetermined range, as shown in FIG. 5, a temperature at which the surface temperature of the second heat exchanging unit 16 is equal to or lower than the dew point temperature can be cited. That is, during the reheat dehumidifying operation, the control unit 20 opens the indoor expansion valve 17 so that the refrigerant flowing in the second heat exchange unit 16 keeps the surface temperature of the second heat exchange unit 16 below the dew point temperature. Adjust the degree. During the reheat dehumidifying operation, the liquefied refrigerant flows into the second heat exchange unit 16 that functions as an evaporator. This refrigerant receives heat from the air in contact with the second heat exchange unit 16, gasifies, and flows out from the second heat exchange unit 16. Thereby, in the 2nd heat exchange part 16, dehumidification of air is performed. However, if the temperature of the refrigerant in the second heat exchange unit 16 is high and there are many refrigerants that have already been gasified, the amount of heat that the refrigerant can receive from the air decreases, so the dehumidifying capacity of the second heat exchange unit 16 itself is reduced. It will decline. In particular, in the present embodiment, since the mixed refrigerant (mixed refrigerant of HFO-1234yf and HFC-32) having a characteristic that the degree of change in temperature during evaporation is relatively large is used, the second heat exchange unit 16 itself. There is a high risk that the dehumidifying capacity of the will decrease. However, the control unit 20 according to the present embodiment controls the temperature of the refrigerant so that the surface temperature of the second heat exchange unit 16 is kept below the dew point temperature by adjusting the opening of the indoor expansion valve 17. Even if the mixed refrigerant is used, the dehumidifying ability of the second heat exchange unit 16 is ensured. In FIG. 5, the temperature of the refrigerant when the surface temperature of the second heat exchange unit 16 is the dew point temperature is represented as “temperature A”. As temperature A, dew point temperature is mentioned. That is, in this case, the range in which the refrigerant is not higher than the dew point temperature is the predetermined range.

ところで、再熱除湿運転時、第２熱交換部１６内の冷媒は、上述したように熱を受け取り、温度が上昇した状態で第２熱交換部１６から流出するため、冷媒は、第２熱交換部１６から流出する時の温度よりも低い温度で第２熱交換部１６内に流入することになる（図５）。この時、既に述べたように、第２熱交換部１６の表面温度が露点温度以下となるように冷媒の温度制御が行われるが、冷媒の温度が低すぎると、場合によっては、室内側膨張弁１７を流出して第２熱交換部１６内に流入する冷媒との熱交換によって、第２熱交換部１６の流入口付近の空気（即ち、第２熱交換部１６の流入口の周囲の空気）に含まれる水分が氷結してしまい、着霜する恐れがある。そこで、本実施形態に係る制御部２０は、第２熱交換部１６の流入口付近の温度が水の氷結する温度以上となるように、室内側膨張弁１７の開度を調整することによって、更なる冷媒の温度の制御を行う。これにより、第２熱交換部１６の流入口における着霜を防ぐことができる。尚、図５では、冷媒との熱交換によって空気中に含まれる水が氷結してしまう時の冷媒の温度を、“温度Ｂ”として表している。 By the way, during the reheat dehumidifying operation, the refrigerant in the second heat exchange unit 16 receives heat as described above and flows out of the second heat exchange unit 16 in a state where the temperature has risen. It flows into the 2nd heat exchange part 16 at the temperature lower than the temperature at the time of flowing out from the exchange part 16 (FIG. 5). At this time, as already described, the temperature control of the refrigerant is performed so that the surface temperature of the second heat exchange unit 16 is equal to or lower than the dew point temperature. If the temperature of the refrigerant is too low, the indoor expansion may occur. By the heat exchange with the refrigerant flowing out of the valve 17 and flowing into the second heat exchange unit 16, air near the inlet of the second heat exchange unit 16 (that is, around the inlet of the second heat exchange unit 16). Moisture contained in the air) may freeze and form frost. Therefore, the control unit 20 according to the present embodiment adjusts the opening degree of the indoor expansion valve 17 so that the temperature in the vicinity of the inlet of the second heat exchange unit 16 is equal to or higher than the temperature at which water freezes. Further control of the refrigerant temperature is performed. Thereby, the frost formation in the inflow port of the 2nd heat exchange part 16 can be prevented. In FIG. 5, the temperature of the refrigerant when water contained in the air freezes due to heat exchange with the refrigerant is represented as “temperature B”.

まとめると、本実施形態に係る制御部２０は、再熱除湿運転時、図４に示すように、暖房サイクルと同様のサイクルで冷媒が循環するように、四路切換弁１２の循環方向の切換制御を行う。この制御と共に、制御部２０は、第２熱交換部１６の流入口付近の温度が水の氷結する温度以上であって、かつ第２熱交換部１６の表面温度が露点温度以下となるように、室内側膨張弁１７の開度を調整することで、冷媒の温度を制御する。即ち、制御部２０は、図５に示すように、第２熱交換部１６に流入する冷媒の温度が“温度Ｂ”以上かつ“温度Ａ”以下であって、第２熱交換部１６から流出する冷媒の温度が“温度Ａ”以下を保った状態となるように、室内側膨張弁１７の開度を調整する。これにより、ＨＦＯ−１２３４ｙｆとＨＦＣ−３２との混合冷媒を用いたとしても、第２熱交換部１６の除湿能力の確保を行うことができると共に、第２熱交換部１６の流入口における着霜を防ぐことができる。 In summary, the control unit 20 according to the present embodiment switches the circulation direction of the four-way switching valve 12 so that the refrigerant circulates in the same cycle as the heating cycle as shown in FIG. 4 during the reheat dehumidifying operation. Take control. Along with this control, the control unit 20 ensures that the temperature near the inlet of the second heat exchange unit 16 is equal to or higher than the temperature at which water freezes, and the surface temperature of the second heat exchange unit 16 is equal to or lower than the dew point temperature. The temperature of the refrigerant is controlled by adjusting the opening of the indoor expansion valve 17. That is, as shown in FIG. 5, the control unit 20 causes the temperature of the refrigerant flowing into the second heat exchange unit 16 to be not less than “temperature B” and not more than “temperature A”, and flows out from the second heat exchange unit 16. The opening degree of the indoor expansion valve 17 is adjusted so that the temperature of the refrigerant to be maintained is kept at a temperature equal to or lower than “temperature A”. Thereby, even if it uses the mixed refrigerant | coolant of HFO-1234yf and HFC-32, while being able to ensure the dehumidification capability of the 2nd heat exchange part 16, it is frosting in the inflow port of the 2nd heat exchange part 16 Can be prevented.

（２）再熱除湿運転時の動作
次に、本実施形態の一特徴である再熱除湿運転時の動作について、図４及び図６を用いて説明する。 (2) Operation at the time of reheat dehumidification operation Next, the operation at the time of reheat dehumidification operation which is one feature of the present embodiment will be described with reference to FIGS. 4 and 6.

再熱除湿運転が行われる場合、図４に示すように、四路切換弁１２は、第１ポートａ１及び第３ポートａ３、第２ポートａ２及び第４ポートａ４をそれぞれ接続した第２状態（図４）を採り、冷媒は、図４の矢印の方向に流れる。つまり、再熱除湿運転時、四路切換弁１２は、暖房サイクル（図３）が行われる場合と同様に切り換えられる。この場合、室外熱交換器１３は蒸発器として機能し、室内熱交換器の第１熱交換部１５は凝縮器、第２熱交換部１６は蒸発器としてそれぞれ機能し、暖房サイクルと同様の再熱除湿サイクルが行われる。 When the reheat dehumidifying operation is performed, as shown in FIG. 4, the four-way switching valve 12 is in a second state in which the first port a1, the third port a3, the second port a2, and the fourth port a4 are connected ( 4), the refrigerant flows in the direction of the arrow in FIG. That is, during the reheat dehumidifying operation, the four-way switching valve 12 is switched in the same manner as when the heating cycle (FIG. 3) is performed. In this case, the outdoor heat exchanger 13 functions as an evaporator, the first heat exchange unit 15 of the indoor heat exchanger functions as a condenser, and the second heat exchange unit 16 functions as an evaporator. A thermal dehumidification cycle is performed.

具体的に、冷媒は、圧縮機１１において圧縮されて高温高圧の冷媒となり（図６の点ｃ１。圧力Ｐ３→Ｐ１、エンタルピｈ４→ｈ１）、四路切換弁１２の第２ポートａ２及び第４ポートａ４を経て室内熱交換器の第１熱交換部１５に送られる。この時、第１熱交換部１５は、凝縮器として機能しているため、第１熱交換部１５へと送られてきた冷媒は、室内空気に放熱しながら凝縮し（図６の点ｃ２。エンタルピｈ１→ｈ２、圧力はＰ１）、その後室内側膨張弁１７に流入される。室内側膨張弁１７に流入した高圧冷媒は、エンタルピｈ２を保ったまま圧力Ｐ２まで減圧される（図６の点ｃ３）。尚、圧力Ｐ２は、図５の横軸“流入口”付近においても示されるように、冷媒の温度が“温度Ｂ”以上かつ“温度Ａ”以下の範囲を満たすような値となっている。つまり、冷媒の温度は、第２熱交換部１６の流入口付近の温度が水の氷結する温度以上であって、かつ第２熱交換部１６の表面温度が露点温度以下となるように保たれる。室内側膨張弁１７で減圧された冷媒は、第２熱交換部１６に流入される。第２熱交換部１６は、蒸発器として機能しているため、第２熱交換部１６へと送られてきた冷媒は、室内空気の熱を吸収しながら蒸発し（図６の点ｃ４。エンタルピｈ２→ｈ３、圧力はＰ２）、その後室外側膨張弁１４へと流入される。尚、第２熱交換部１６における冷媒の流入口（つまり、図４の点ｃ３）に設けられた第１パスの本数は、冷媒の流出口（つまり、図６の点ｃ４）に設けられた第２パスの本数よりも少ないため、第２熱交換部１６の流出口側では冷媒の圧力が積極的に損失されるようになる。また、エンタルピｈ３は、図５の横軸“流出口”付近においても示されるように、冷媒の温度が、“温度Ａ”以下、即ち第２熱交換部１６の表面温度が露点温度以下となる範囲を満たすような値となっている。このような室内熱交換器により、室内空気は、第１熱交換部１５において温められた後、第２熱交換部１６によって除湿される。 Specifically, the refrigerant is compressed in the compressor 11 to become a high-temperature and high-pressure refrigerant (point c1 in FIG. 6, pressure P3 → P1, enthalpy h4 → h1), the second port a2 of the four-way switching valve 12 and the fourth It is sent to the 1st heat exchange part 15 of an indoor heat exchanger via port a4. At this time, since the first heat exchanging unit 15 functions as a condenser, the refrigerant sent to the first heat exchanging unit 15 condenses while releasing heat to the room air (point c2 in FIG. 6). Enthalpy h1 → h2, pressure is P1), and then flows into the indoor expansion valve 17. The high-pressure refrigerant that has flowed into the indoor expansion valve 17 is reduced to the pressure P2 while maintaining the enthalpy h2 (point c3 in FIG. 6). Note that the pressure P2 is a value such that the temperature of the refrigerant satisfies the range of “temperature B” or more and “temperature A” or less, as also shown in the vicinity of the “inlet” in the horizontal axis of FIG. That is, the temperature of the refrigerant is maintained such that the temperature near the inlet of the second heat exchange unit 16 is equal to or higher than the temperature at which water freezes, and the surface temperature of the second heat exchange unit 16 is equal to or lower than the dew point temperature. It is. The refrigerant decompressed by the indoor expansion valve 17 flows into the second heat exchange unit 16. Since the second heat exchange unit 16 functions as an evaporator, the refrigerant sent to the second heat exchange unit 16 evaporates while absorbing the heat of the room air (point c4 in FIG. 6; enthalpy). h2 → h3, pressure is P2), and then flows into the outdoor expansion valve 14. The number of first paths provided at the refrigerant inlet (that is, the point c3 in FIG. 4) in the second heat exchange unit 16 is provided at the refrigerant outlet (that is, the point c4 in FIG. 6). Since it is less than the number of second passes, the refrigerant pressure is actively lost on the outlet side of the second heat exchange section 16. In the enthalpy h3, as also shown in the vicinity of the “outlet” in the horizontal axis of FIG. The value satisfies the range. With such an indoor heat exchanger, the room air is warmed in the first heat exchange unit 15 and then dehumidified by the second heat exchange unit 16.

室外側膨張弁１４に流入した冷媒は、ガス状でかつ低圧の冷媒となっている。この冷媒は、室外側膨張弁１４においてエンタルピｈ３を保ったまま更に圧力Ｐ３まで減圧され（図６の点ｃ５）、その後室外熱交換器１３へと送られる。この時、室外熱交換器１３は、蒸発器として機能しているため、室外熱交換器１３へと送られてきた冷媒は、室外空気の熱を吸収しながら蒸発し（図６の点ｃ６。エンタルピｈ３→ｈ４、圧力はＰ３）、その後四路切換弁１２の第３ポートａ３及び第１ポートａ１を経て圧縮機１１に戻される。圧縮機１１に吸入された冷媒は、圧縮機１１において再び昇圧される（図６の点ｃ１）。尚、再熱除湿運転においては、室外機２における室外ファンは、回転を停止した状態となっている。 The refrigerant that has flowed into the outdoor expansion valve 14 is a gaseous and low-pressure refrigerant. This refrigerant is further depressurized to the pressure P3 while maintaining the enthalpy h3 in the outdoor expansion valve 14 (point c5 in FIG. 6), and then sent to the outdoor heat exchanger 13. At this time, since the outdoor heat exchanger 13 functions as an evaporator, the refrigerant sent to the outdoor heat exchanger 13 evaporates while absorbing the heat of the outdoor air (point c6 in FIG. 6). The enthalpy h3 → h4, the pressure is P3), and then returned to the compressor 11 through the third port a3 and the first port a1 of the four-way switching valve 12. The refrigerant sucked into the compressor 11 is again pressurized in the compressor 11 (point c1 in FIG. 6). In the reheat dehumidifying operation, the outdoor fan in the outdoor unit 2 is in a stopped state.

（３）効果
（Ａ）
本実施形態に係る空気調和装置１によると、再熱除湿運転時には、暖房サイクルが行われると共に、蒸発器として機能する第２熱交換部１６内を流れる冷媒の温度は所定範囲内に保たれる。ここで、所定範囲は、第２熱交換部１６が除湿を行うことができる温度範囲であるため、第２熱交換部１６の表面温度は除湿できる温度以下に保たれる。従って、再熱除湿運転の性能を向上させることができる。 (3) Effect (A)
According to the air conditioner 1 according to the present embodiment, during the reheat dehumidifying operation, a heating cycle is performed, and the temperature of the refrigerant flowing in the second heat exchange unit 16 functioning as an evaporator is kept within a predetermined range. . Here, since the predetermined range is a temperature range in which the second heat exchange unit 16 can perform dehumidification, the surface temperature of the second heat exchange unit 16 is kept below a temperature at which dehumidification is possible. Therefore, the performance of the reheat dehumidification operation can be improved.

（Ｂ）
また、本実施形態に係る空気調和装置１によると、第１熱交換部１５と第２熱交換部１６との間の室内側膨張弁１７の開度が制御部２０によって調整される。これにより、第２熱交換部１６内の冷媒の温度が所定範囲内に保たれるようになる。 (B)
Moreover, according to the air conditioning apparatus 1 according to the present embodiment, the opening degree of the indoor expansion valve 17 between the first heat exchange unit 15 and the second heat exchange unit 16 is adjusted by the control unit 20. Thereby, the temperature of the refrigerant | coolant in the 2nd heat exchange part 16 comes to be maintained in a predetermined range.

（Ｃ）
また、本実施形態に係る空気調和装置１によると、再熱除湿運転時には、第２熱交換部１６の流入口（具体的には、図４の点ｃ３）付近の温度が水の氷結する温度以上となるように、冷媒の温度が制御されるため、第２熱交換部１６の流入口付近が着霜してしまうのを防ぐことができる。 (C)
Moreover, according to the air conditioning apparatus 1 which concerns on this embodiment, at the time of a reheat dehumidification operation, the temperature near the inflow port (specifically, point c3 of FIG. 4) of the second heat exchange unit 16 is a temperature at which water freezes. As described above, since the temperature of the refrigerant is controlled, it is possible to prevent the vicinity of the inlet of the second heat exchange unit 16 from frosting.

（Ｄ）
また、本実施形態に係る空気調和装置１では、冷媒として、ジフルオロメタン（即ち、ＨＦＣ−３２）を含む混合冷媒が用いられる。この冷媒では、同一圧力において乾き度が比較的大きいと温度が上昇するといった特性が顕著となる。しかし、本実施形態に係る空気調和装置１は、ＨＦＣ−３２を含む混合冷媒を採用しても、再熱除湿運転時には暖房サイクルを行い、かつ蒸発器として機能する第２熱交換部１６内を流れる冷媒の温度を所定範囲内に保つため、再熱除湿運転の性能を向上させることが可能となる。 (D)
Moreover, in the air conditioning apparatus 1 which concerns on this embodiment, the mixed refrigerant | coolant containing difluoromethane (namely, HFC-32) is used as a refrigerant | coolant. This refrigerant has a remarkable characteristic that the temperature rises when the dryness is relatively large at the same pressure. However, even if the air-conditioning apparatus 1 according to the present embodiment employs a mixed refrigerant including HFC-32, the second heat exchange unit 16 that performs a heating cycle and functions as an evaporator during the reheat dehumidifying operation is used. Since the temperature of the flowing refrigerant is kept within a predetermined range, the performance of the reheat dehumidification operation can be improved.

（Ｅ）
また、本実施形態に係る空気調和装置１は、再熱除湿運転時、第２熱交換部１６の表面温度が露点温度以下となるように、冷媒の温度を制御するため、第２熱交換部１６は、確実に除湿できるようになる。 (E)
Moreover, since the air conditioning apparatus 1 which concerns on this embodiment controls the temperature of a refrigerant | coolant so that the surface temperature of the 2nd heat exchange part 16 may become below a dew point temperature at the time of a reheat dehumidification operation, it is 2nd heat exchange part. 16 can reliably dehumidify.

（Ｆ）
また、本実施形態に係る空気調和装置１によると、再熱除湿運転時における第２熱交換部１６の流入口側の第１パスは、第２熱交換部１６の流出口側の第２パスよりも本数が少ないため、再熱除湿運転時に蒸発器として機能する第２熱交換部１６の流出口側における冷媒の圧力損失を積極的につけることができる。 (F)
Moreover, according to the air conditioning apparatus 1 according to the present embodiment, the first path on the inlet side of the second heat exchange unit 16 during the reheat dehumidifying operation is the second path on the outlet side of the second heat exchange unit 16. Therefore, it is possible to positively apply a refrigerant pressure loss on the outlet side of the second heat exchange unit 16 that functions as an evaporator during the reheat dehumidifying operation.

＜その他の実施形態＞
（ａ）
上記実施形態では、再熱除湿運転時における第２熱交換部１６の流入口側の第１パスの本数を、第２熱交換部１６の流出口側の第２パスの本数よりも少なくすることで、再熱除湿運転時に蒸発器として機能する第２熱交換部１６の、流出口側における冷媒の圧力損失を積極的につけると説明した。しかし、第２熱交換部１６の流出口側における冷媒の圧力損失を積極的につける方法は、これに限定されない。再熱除湿運転において、第２熱交換部１６における冷媒の流入口に設けられた第１パス（第３パスに相当）の径を、冷媒の流出口に設けられた第２パス（第４パスに相当）の径よりも小さくする方法でも、上記実施形態と同様、第２熱交換部１６の流出口側における冷媒の圧力損失を積極的につけることができる。 <Other embodiments>
(A)
In the above embodiment, the number of first passes on the inlet side of the second heat exchange unit 16 during the reheat dehumidification operation is made smaller than the number of second passes on the outlet side of the second heat exchange unit 16. Thus, it has been explained that the pressure loss of the refrigerant on the outlet side of the second heat exchange unit 16 that functions as an evaporator during the reheat dehumidifying operation is positively applied. However, the method of positively applying the refrigerant pressure loss on the outlet side of the second heat exchange unit 16 is not limited to this. In the reheat dehumidifying operation, the diameter of the first path (corresponding to the third path) provided at the refrigerant inlet in the second heat exchange unit 16 is set to the second path (fourth path) provided at the refrigerant outlet. In the same manner as in the above embodiment, the pressure loss of the refrigerant on the outlet side of the second heat exchange unit 16 can be positively applied even by the method of making the diameter smaller than the diameter of

（ｂ）
上記実施形態では、冷媒回路１０を循環する冷媒が、ＨＦＯ−１２３４ｙｆとＨＦＣ−３２との混合冷媒である場合を例に取り説明した。しかし、本発明において利用される混合冷媒は、Ｃ₃Ｈ_mＦ_n（但し、ｍ＝１〜５，ｎ＝１〜５且つｍ＋ｎ＝６）の分子式で示され、且つ分子構造中に二重結合を１個有する冷媒を含む混合冷媒であればよく、上記混合冷媒に限定されない。つまり、本発明において利用される混合冷媒は、蒸発中の温度が変化する度合いが比較的大きい特性を有する冷媒であればよく、上記混合冷媒に限定されない。 (B)
In the above embodiment, the case where the refrigerant circulating in the refrigerant circuit 10 is a mixed refrigerant of HFO-1234yf and HFC-32 has been described as an example. However, the mixed refrigerant used in the present invention is represented by a molecular formula of C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6), and double in the molecular structure. Any mixed refrigerant including a refrigerant having one bond may be used, and the present invention is not limited to the mixed refrigerant. That is, the mixed refrigerant used in the present invention is not limited to the above mixed refrigerant as long as it has a characteristic that the degree of change in temperature during evaporation is relatively large.

（ｃ）
上記実施形態では、図５に示すように、第２熱交換部１６の流入口付近の温度が水の氷結する温度以上であって（温度Ｂ）、かつ第２熱交換部１６の表面温度が露点温度以下（温度Ａ）であるという条件を満たすように、第２熱交換部１６に流入される冷媒の温度を調節すると共に、この冷媒は、第２熱交換部１６の表面温度が露点温度以下という条件を満たした温度のまま（即ち、冷媒が“温度Ａ”以下のまま）第２熱交換部１６内を流れて流出すると説明した。しかし、本発明に係る空気調和装置１では、再熱除湿運転時に蒸発器として機能する第２熱交換部１６内には、少なくとも第２熱交換部１６の表面温度が除湿できる温度以下に保たれるような温度範囲の冷媒が流れれば良い。従って、第２熱交換部１６内を流れる冷媒は、第２熱交換部１６の表面温度が露点温度以下という条件のみを満たしていてもよく、冷媒の温度は、流入口付近の温度が“水の氷結する温度以上”という条件を必ずしも満たしていなくともよい。 (C)
In the above embodiment, as shown in FIG. 5, the temperature near the inlet of the second heat exchange unit 16 is equal to or higher than the temperature at which the water freezes (temperature B), and the surface temperature of the second heat exchange unit 16 is The temperature of the refrigerant flowing into the second heat exchange unit 16 is adjusted so as to satisfy the condition that the temperature is equal to or lower than the dew point temperature (temperature A), and the surface temperature of the second heat exchange unit 16 is dew point temperature. It has been described that the temperature satisfies the following conditions (that is, the refrigerant remains below “temperature A”) and flows through the second heat exchange unit 16 and flows out. However, in the air conditioning apparatus 1 according to the present invention, at least the surface temperature of the second heat exchange unit 16 is kept at a temperature that can be dehumidified in the second heat exchange unit 16 that functions as an evaporator during the reheat dehumidification operation. It suffices if a refrigerant in such a temperature range flows. Therefore, the refrigerant flowing in the second heat exchange unit 16 may satisfy only the condition that the surface temperature of the second heat exchange unit 16 is equal to or lower than the dew point temperature. It is not always necessary to satisfy the condition “above freezing temperature”.

本発明に係る空気調和装置は、再熱除湿運転の性能を向上させることができるという効果を奏することから、蒸発中の温度が変化する度合いが比較的大きい特性を有する混合冷媒を利用した空気調和装置として適用することができる。 The air conditioner according to the present invention has an effect that the performance of the reheat dehumidification operation can be improved. Therefore, the air conditioner using the mixed refrigerant having the characteristic that the temperature during evaporation is relatively large. It can be applied as a device.

本実施形態に係る空気調和装置の外観図。The external view of the air conditioning apparatus which concerns on this embodiment. 本実施形態に係る空気調和装置が冷房運転時に行う冷房サイクルを示す冷媒回路図。The refrigerant circuit figure which shows the cooling cycle which the air conditioning apparatus which concerns on this embodiment performs at the time of cooling operation. 本実施形態に係る空気調和装置が暖房運転時に行う暖房サイクルを示す冷媒回路図。The refrigerant circuit figure which shows the heating cycle which the air conditioning apparatus which concerns on this embodiment performs at the time of heating operation. 本実施形態に係る空気調和装置が再熱除湿運転時に行う再熱除湿サイクルを示す冷媒回路図。The refrigerant circuit figure which shows the reheat dehumidification cycle which the air conditioning apparatus which concerns on this embodiment performs at the time of a reheat dehumidification driving | operation. 再熱除湿運転時における、第２熱交換部内を流れる冷媒の温度変化を示す図。The figure which shows the temperature change of the refrigerant | coolant which flows through the inside of the 2nd heat exchange part at the time of a reheat dehumidification driving | operation. 本実施形態に係る空気調和装置が再熱除湿運転を行った場合の再熱除湿サイクル図。The reheat dehumidification cycle figure when the air conditioning apparatus which concerns on this embodiment performs the reheat dehumidification driving | operation.

Explanation of symbols

１空気調和装置
２室外機
３室内機
４ａ，４ｂ冷媒配管
１０冷媒回路
１０ａ熱源側回路
１０ｂ利用側回路
１１圧縮機
１２四路切換弁（切り換え機構）
１３室外熱交換器（熱源側熱交換器）
１４室外側膨張弁（第１膨張機構）
１５第１熱交換部
１６第２熱交換部
１７室内側膨張弁（第２膨張機構）
２０制御部 DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 3 Indoor unit 4a, 4b Refrigerant piping 10 Refrigerant circuit 10a Heat source side circuit 10b Use side circuit 11 Compressor 12 Four-way switching valve (switching mechanism)
13 Outdoor heat exchanger (heat source side heat exchanger)
14 Outdoor expansion valve (first expansion mechanism)
15 1st heat exchange part 16 2nd heat exchange part 17 Indoor side expansion valve (2nd expansion mechanism)
20 Control unit

Claims

A refrigerant circuit (10) including a compressor (11), a heat source side heat exchanger (13), a first expansion mechanism (14), and a use side heat exchanger (15, 16);
A switching mechanism (12) for switching the circulation direction of the refrigerant in the refrigerant circuit (10);
A control unit (20) for performing switching control of the circulation direction of the switching mechanism (12) so that a cooling cycle is performed during the cooling operation and a heating cycle is performed during the heating operation;
With
The use side heat exchangers (15, 16) function as an evaporator during the cooling operation and function as a condenser during the reheat dehumidification operation, and during the cooling operation and the reheat dehumidification operation. A second heat exchange section (16) functioning as an evaporator,
The refrigerant is a mixture containing a refrigerant represented by a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6) and having one double bond in the molecular structure. A refrigerant,
The control unit (20) performs switching control of the circulation direction of the switching mechanism (12) so that the heating cycle is performed during the reheat dehumidification operation, and the inside of the second heat exchange unit (16). Controlling the temperature of the refrigerant so that the temperature of the flowing refrigerant is maintained within a predetermined range;
Air conditioner (1).

The refrigerant circuit (10) further includes a second expansion mechanism (17) provided between the first heat exchange part (15) and the second heat exchange part (16),
The controller (20) controls the temperature of the refrigerant by adjusting the opening of the second expansion mechanism (17).
The air conditioner (1) according to claim 1.

The control unit (20) includes the second heat exchange unit when the refrigerant that has flowed out of the second expansion mechanism (17) flows into the second heat exchange unit (16) during the reheat dehumidification operation. Adjusting the opening of the second expansion mechanism (17) so that the temperature in the vicinity of the inlet of (26) is equal to or higher than the temperature at which water freezes;
The air conditioner (1) according to claim 2.

The refrigerant is a mixed refrigerant further containing difluoromethane.
The air conditioning apparatus (1) according to any one of claims 1 to 3.

The predetermined range is a range in which the surface temperature of the second heat exchange part (16) is equal to or lower than a dew point temperature.
The air conditioning apparatus (1) according to any one of claims 1 to 4.

In the reheat dehumidifying operation, the number of first passes provided at the refrigerant inlet in the second heat exchange section (16) is less than the number of second passes provided at the refrigerant outlet. ,
The air conditioner (1) according to any one of claims 1 to 5.

In the reheat dehumidifying operation, the diameter of the third path provided at the refrigerant inlet in the second heat exchange section (16) is smaller than the diameter of the fourth path provided at the refrigerant outlet. ,
The air conditioning apparatus (1) according to any one of claims 1 to 6.