JP5492523B2

JP5492523B2 - Air conditioner

Info

Publication number: JP5492523B2
Application number: JP2009242934A
Authority: JP
Inventors: 直之伏見; 博之川口; 純一郎手塚; 信一郎永松
Original assignee: Hitachi Appliances Inc
Current assignee: Hitachi Appliances Inc
Priority date: 2009-10-22
Filing date: 2009-10-22
Publication date: 2014-05-14
Anticipated expiration: 2029-10-22
Also published as: BRPI1004134A8; BRPI1004134A2; CN102042660B; JP2011089690A; BRPI1004134B1; CN102042660A

Description

本発明は、水を熱源とする熱源側熱交換器を備え、この熱源側熱交換器内部に流れる水の凍結保護を行うようにした空気調和機に係り、特にプレート式熱交換器に好適なものである。 The present invention relates to an air conditioner that includes a heat source side heat exchanger that uses water as a heat source, and that protects the water flowing inside the heat source side heat exchanger from being frozen, and is particularly suitable for a plate type heat exchanger. Is.

近年、環境問題は地球規模での課題となっており、省エネルギー化が一つの解決策として挙げられる。水を熱源とする熱源側熱交換器を有する空気調和機では、未利用熱源（地下水や設備からの排熱等）を利用できる。また、水と冷媒との間で熱交換が行われる場合は熱交換効率が良く、空気を熱源とする一般的な空気調和機より省エネルギー性が高いため、環境負荷が低い。一方、この熱交換器は水と冷媒とで熱交換を行うため、冷媒温度がマイナスになると水が凍り、凍った水が熱交換器内で膨張して熱交換器を破損させるおそれがある。 In recent years, environmental problems have become a global issue, and energy saving is one possible solution. In an air conditioner having a heat source side heat exchanger that uses water as a heat source, an unused heat source (such as groundwater or waste heat from equipment) can be used. Moreover, when heat exchange is performed between water and a refrigerant, the heat exchange efficiency is good, and energy saving is higher than a general air conditioner using air as a heat source, so the environmental load is low. On the other hand, since this heat exchanger performs heat exchange between water and the refrigerant, when the refrigerant temperature becomes negative, the water freezes, and the frozen water may expand in the heat exchanger and damage the heat exchanger.

特許文献１には、多室型の空気調和機において、サーミスタを熱交換器の各冷媒ガス側に設置し、サーミスタによって測定された冷媒ガス温度に基づいて、熱交換器に水が十分に流れているかどうかを判定し、水が十分に流れていないと判定した場合は、圧縮手段に運転停止指令を行うことで熱交換器の凍結を防止することが記載されている。 In Patent Document 1, in a multi-room type air conditioner, a thermistor is installed on each refrigerant gas side of the heat exchanger, and water flows sufficiently to the heat exchanger based on the refrigerant gas temperature measured by the thermistor. It is described that the heat exchanger is prevented from freezing by issuing an operation stop command to the compression means when it is determined that the water is not flowing sufficiently.

特許文献２には、冷凍装置において、プレート式熱交換器の冷温水が流出する冷温水出口の近傍に凍結防止センサを設けて、冷温水温度が最も低い温度となる冷温水出口の温度を検出して冷水の凍結を判断し、圧縮機等の運転を制御することで冷水の凍結を防止することが記載されている。 In Patent Document 2, in a refrigeration apparatus, a freeze prevention sensor is provided in the vicinity of a cold / hot water outlet from which cold / hot water flows out of a plate heat exchanger, and the temperature of the cold / hot water outlet at which the cold / hot water temperature is the lowest is detected. Thus, it is described that the freezing of cold water is judged and the freezing of the cold water is prevented by controlling the operation of the compressor or the like.

特許４１８６４９２号公報Japanese Patent No. 4186492 特開２００５−１８８７６５号公報JP 2005-188765 A

しかし、上記特許文献１の空気調和機は、運転中に水が供給されなくなった場合には、液冷媒が水と熱交換できず、液冷媒が熱交換器内に溜まるため、室外膨張弁の開度を蒸発能力に合わせて調整し、熱交換器出口の冷媒を一定過熱度のガスに制御する。そのため、熱交換器出口のガス管温度はすぐに低下せずに冷媒温度のみが低下し、保護が働く前に熱交換器内の水は凍結してしまう。 However, in the air conditioner of Patent Document 1, when water is not supplied during operation, the liquid refrigerant cannot exchange heat with water, and the liquid refrigerant accumulates in the heat exchanger. The opening degree is adjusted according to the evaporation capacity, and the refrigerant at the outlet of the heat exchanger is controlled to a gas with a certain degree of superheat. For this reason, the temperature of the gas pipe at the outlet of the heat exchanger does not decrease immediately, only the refrigerant temperature decreases, and the water in the heat exchanger freezes before protection is activated.

また、上記特許文献２の冷凍装置は、水が供給されなくなった場合には冷温水出口に水が流れてこないため、熱交換器内部の正確な水温を測ることができず、水が流れなくなった直後に空調機の負荷変動等により急激に冷媒温度が下がった場合には冷水の凍結を判断することができない。 In the refrigeration apparatus of Patent Document 2, when water is not supplied, water does not flow to the cold / hot water outlet, so the accurate water temperature inside the heat exchanger cannot be measured, and water does not flow. Immediately after that, when the refrigerant temperature suddenly drops due to the load fluctuation of the air conditioner or the like, it is not possible to determine whether or not the cold water is frozen.

本発明の目的は、運転中に水の供給がなくなった場合及び圧縮機起動時に水の供給がない場合に運転を停止し、凍結を防止できる空気調和機を得ることにある。 An object of the present invention is to obtain an air conditioner capable of stopping operation and preventing freezing when water is not supplied during operation and when water is not supplied when the compressor is started.

本発明の他の目的は、圧縮機起動前に水の供給がない場合は運転を開始せず、凍結を防止できる空気調和機を得ることにある。 Another object of the present invention is to obtain an air conditioner that can prevent freezing without starting operation when water is not supplied before the compressor is started.

前記課題を解決するため、本発明の特徴は、水が流れる第１プレートと冷媒が流れる第２プレートとを有するプレート式熱交換器、圧縮機、室外膨張弁、を備える室外機と、室内熱交換器を備える室内機とを冷媒配管で接続した空気調和機において、前記プレート式熱交換器の冷媒入口ノズルと冷媒出口ノズルのある面と垂直となる鉛直方向の面において前記プレート式熱交換器の高さ方向の略中心より下側であって、前記冷媒入口ノズルより上側に温度センサを備え、前記第１プレートの水と前記第２プレートの冷媒との両方を反映した温度を前記温度センサで測定し、前記温度センサの値が所定の値以下となる場合に前記圧縮機の運転を停止することにある。 In order to solve the above problems, the present invention is characterized in that an outdoor unit including a plate heat exchanger having a first plate through which water flows and a second plate through which refrigerant flows, a compressor, and an outdoor expansion valve, and indoor heat In an air conditioner in which an indoor unit including an exchanger is connected by a refrigerant pipe, the plate heat exchanger is disposed on a vertical surface perpendicular to a surface where the refrigerant inlet nozzle and the refrigerant outlet nozzle of the plate heat exchanger are provided. The temperature sensor is provided with a temperature sensor below the approximate center in the height direction and above the refrigerant inlet nozzle, and the temperature sensor reflects the temperature reflecting both the water in the first plate and the refrigerant in the second plate. And the operation of the compressor is stopped when the value of the temperature sensor becomes a predetermined value or less.

水が流れる第１プレートと冷媒が流れる第２プレートとを有するプレート式熱交換器、圧縮機、室外膨張弁、を備える室外機と、室内熱交換器を備える室内機とを冷媒配管で接続した空気調和機において、前記プレート式熱交換器の冷媒入口ノズルと冷媒出口ノズルのある面と垂直となる鉛直方向の面において、前記プレート式熱交換器に水が供給されている場合は気液二相冷媒が貯留する部分であって、前記プレート式熱交換器に水が供給されていない場合は液冷媒が貯留する部分に温度センサを備え、前記第１プレートの水と前記第２プレートの冷媒との両方を反映した温度を前記温度センサで測定し、前記温度センサの値が所定の値以下となる場合に前記圧縮機の運転を停止することが望ましい。 A plate heat exchanger having a first plate through which water flows and a second plate through which refrigerant flows, an outdoor unit including a compressor and an outdoor expansion valve, and an indoor unit including an indoor heat exchanger are connected by a refrigerant pipe. In the air conditioner , when water is supplied to the plate heat exchanger on a surface in a vertical direction perpendicular to the surfaces of the refrigerant inlet nozzle and the refrigerant outlet nozzle of the plate heat exchanger, When the plate-type heat exchanger is not supplied with water, a temperature sensor is provided in the portion where the liquid refrigerant is stored , and the first plate water and the second plate refrigerant are stored. It is desirable to measure the temperature reflecting both the above and the temperature sensor, and to stop the operation of the compressor when the value of the temperature sensor becomes a predetermined value or less .

本発明の他の特徴は、水が流れる第１プレートと冷媒が流れる第２プレートとを有するプレート式熱交換器、圧縮機、室外膨張弁、を備える室外機と、室内熱交換器を備える室内機とを冷媒配管で接続した空気調和機において、前記プレート式熱交換器の冷媒入口ノズルと冷媒出口ノズルのある面と垂直となる鉛直方向の面において前記プレート式熱交換器の高さ方向の略中心より下側であって、前記冷媒入口ノズルより上側に温度センサを備え、前記圧縮機の運転開始前に前記第１プレートの水と前記第２プレートの冷媒との両方を反映した温度を前記温度センサで測定し、前記温度センサの値が所定の値以上である場合に前記圧縮機の運転を開始させることにある。
Other features of the present invention include a plate heat exchanger having a first plate through which water flows and a second plate through which refrigerant flows, an outdoor unit including a compressor and an outdoor expansion valve, and an indoor unit including an indoor heat exchanger. in an air conditioner and a machine are connected by refrigerant pipes, the height of Oite the plate heat exchanger in a vertical direction of the surface to be perpendicular to the surface with a coolant inlet nozzle and the refrigerant outlet nozzles of the plate heat exchanger A temperature sensor is provided below the approximate center of the direction and above the refrigerant inlet nozzle, and reflects both the water in the first plate and the refrigerant in the second plate before the operation of the compressor is started. The temperature is measured by the temperature sensor, and the operation of the compressor is started when the value of the temperature sensor is equal to or higher than a predetermined value.

更に、前記室内機を複数備えるものでもよい。 Further, a plurality of the indoor units may be provided.

本発明によれば、プレート式熱交換器の側面に温度センサを備え、水が流れるプレートと冷媒が流れるプレートの温度を温度センサで測定し、この温度センサの値が所定の値以下となる場合に圧縮機の運転を停止するように構成したので、運転中に水の供給がなくなった場合及び圧縮機起動時に水の供給がない場合に運転を停止し、凍結を防止できる。 According to the present invention, a temperature sensor is provided on the side surface of the plate heat exchanger, and the temperature of the plate through which water flows and the plate through which the refrigerant flows are measured by the temperature sensor, and the value of the temperature sensor is equal to or less than a predetermined value. Since the operation of the compressor is stopped, the operation is stopped when the supply of water is stopped during the operation and when the supply of water is not performed at the time of starting the compressor, and freezing can be prevented.

また、圧縮機の運転開始前に水が流れるプレートと冷媒が流れるプレートの温度を温度センサで測定し、温度センサの値が所定の値以上である場合に圧縮機の運転を開始させるように構成したので、圧縮機起動前に水の供給がない場合は運転を開始せず、凍結を防止できる。 Further, the temperature sensor measures the temperature of the plate through which water flows and the plate through which the refrigerant flows before starting the compressor operation, and the compressor operation is started when the temperature sensor value is equal to or higher than a predetermined value. Therefore, when there is no water supply before the compressor is started, the operation is not started and freezing can be prevented.

本発明の実施例１における冷凍サイクル構成図。The refrigeration cycle block diagram in Example 1 of this invention. 熱源側熱交換器の冷媒圧力と冷媒温度との関係を示す図。The figure which shows the relationship between the refrigerant | coolant pressure and refrigerant | coolant temperature of a heat source side heat exchanger. 本発明の実施例１における熱源側熱交換器周りの構成図。The block diagram of the circumference | surroundings of the heat source side heat exchanger in Example 1 of this invention. 従来技術における熱源側熱交換器凍結時の温度変化を示す図。The figure which shows the temperature change at the time of the heat source side heat exchanger freezing in a prior art. 本発明の実施例１における熱源側熱交換器凍結時の温度変化を示す図。The figure which shows the temperature change at the time of the heat source side heat exchanger freezing in Example 1 of this invention. 本発明の実施例１における熱源側熱交換器の温度センサ取付面を示す図。The figure which shows the temperature sensor mounting surface of the heat source side heat exchanger in Example 1 of this invention. 本発明の実施例１における熱源側熱交換器に通水された状態と断水状態での熱源側熱交換器の高さ方向の冷媒状態を示す図。The figure which shows the refrigerant | coolant state of the height direction of the heat source side heat exchanger in the state by which it flowed in the heat source side heat exchanger in Example 1 of this invention, and a water stop state. 本発明の実施例１における熱源側熱交換器に通水された状態と断水状態での温度センサ取付位置Ｃ部の温度特性を示す図。The figure which shows the temperature characteristic of the temperature sensor attachment position C part in the state by which the water was passed through the heat-source side heat exchanger in Example 1 of this invention, and a water cutoff state. 本発明の実施例１における熱源側熱交換器に通水された状態と断水状態での熱源側熱交換器の部分別温度特性を示す図。The figure which shows the temperature characteristic according to part of the heat source side heat exchanger in the state by which it flowed in the heat source side heat exchanger in Example 1 of this invention, and a water cutoff state. 本発明の実施例２における凍結保護の制御を説明するフローチャート。The flowchart explaining the control of freeze protection in Example 2 of this invention.

以下、図を参照して本発明の実施例を説明する。 Embodiments of the present invention will be described below with reference to the drawings.

図１は本実施例の空気調和機の冷凍サイクル構成図である。空気調和機は、熱源ユニットである室外機１と２台の室内機２３とが、液接続配管２２，ガス接続配管２１によって接続されている。室内機２３は１台でも複数台でも良い。室外機１は運転周波数をインバータで可変制御される容量可変式の圧縮機２を有し、圧縮機２と四方弁３とが接続されている。圧縮機２の低圧側には受液器６を備えている。四方弁３はガス冷媒配管１０によって熱源側熱交換器４と接続される。熱源側熱交換器４と室外膨張弁５は液冷媒配管１１で接続される。 FIG. 1 is a configuration diagram of the refrigeration cycle of the air conditioner of this embodiment. In the air conditioner, an outdoor unit 1 that is a heat source unit and two indoor units 23 are connected by a liquid connection pipe 22 and a gas connection pipe 21. One or a plurality of indoor units 23 may be provided. The outdoor unit 1 has a variable capacity compressor 2 whose operating frequency is variably controlled by an inverter, and the compressor 2 and the four-way valve 3 are connected to each other. A liquid receiver 6 is provided on the low pressure side of the compressor 2. The four-way valve 3 is connected to the heat source side heat exchanger 4 by a gas refrigerant pipe 10. The heat source side heat exchanger 4 and the outdoor expansion valve 5 are connected by a liquid refrigerant pipe 11.

熱源ユニットは水を熱源としており、熱源側熱交換器４は図３に示すようなプレート式熱交換器が用いられる。このプレート式熱交換器４には水配管１５によってユニット外部から水が供給され、冷媒との間で熱交換する。この水は、温度と流量が規定の範囲になるように調整され、ボイラや冷水設備から送られる。 The heat source unit uses water as a heat source, and the heat source side heat exchanger 4 is a plate heat exchanger as shown in FIG. Water is supplied to the plate heat exchanger 4 from the outside of the unit through a water pipe 15 to exchange heat with the refrigerant. This water is adjusted so that the temperature and flow rate are within a specified range, and sent from a boiler or cold water equipment.

また、圧縮機２の高圧側には高圧圧力センサ７、低圧側には低圧圧力センサ８を備え、熱源側熱交換器４の側面には温度センサ９が設けられている。 The compressor 2 includes a high pressure sensor 7 on the high pressure side, a low pressure sensor 8 on the low pressure side, and a temperature sensor 9 on the side surface of the heat source side heat exchanger 4.

まず熱源側熱交換器４が凍結する過程を説明する。暖房時には、熱源側熱交換器４は蒸発器となり、低温低圧の冷媒が流れ込み、外部の設備から供給された水から熱を奪い蒸発する。水は熱を奪われ温度が下がる。 First, the process of freezing the heat source side heat exchanger 4 will be described. At the time of heating, the heat source side heat exchanger 4 becomes an evaporator, and a low-temperature and low-pressure refrigerant flows in, evaporates by taking heat from water supplied from external equipment. Water is deprived of heat and the temperature drops.

図２に示すように、熱交換器入口の冷媒温度は圧力に依存し、その圧力は圧縮機の低圧圧力とほぼ同値になる。熱交換器内の水の最低温度はこの冷媒温度と同値になると考えられる。ここで、冷媒温度がマイナスになる圧力をＰ１とし、運転時はＰ１以上を保つように圧縮機周波数を制御する。例えば低圧圧力がＰ１を下回ったら、圧縮機周波数を落として低圧圧力をＰ１以上に回復させるという保護方法が一般的である。 As shown in FIG. 2, the refrigerant temperature at the heat exchanger inlet depends on the pressure, and the pressure is substantially the same as the low pressure of the compressor. It is considered that the minimum temperature of water in the heat exchanger is equivalent to this refrigerant temperature. Here, the pressure at which the refrigerant temperature becomes negative is P1, and the compressor frequency is controlled so as to maintain P1 or higher during operation. For example, when the low-pressure pressure falls below P1, a protection method is generally used in which the compressor frequency is lowered to restore the low-pressure pressure to P1 or higher.

しかし、前記手段により保護できるのは温度や流量が規定範囲の水が供給されている場合である。水の供給が無くなった場合や規定の使用範囲以下になった場合には圧縮機周波数を下限まで落としても低圧圧力はＰ１を下回る。その結果、冷媒温度はマイナスとなり水が凍結し、熱交換器が破損する。この場合には、圧縮機の運転を停止する必要がある。 However, the above means can protect the water when the temperature and flow rate are in the specified range. When the supply of water is lost or when it falls below the specified use range, the low pressure is below P1 even if the compressor frequency is lowered to the lower limit. As a result, the refrigerant temperature becomes negative, the water freezes, and the heat exchanger is damaged. In this case, it is necessary to stop the operation of the compressor.

次に、本実施例の凍結保護方法について説明する。図３にプレート式熱交換器４とその周囲の図を示す。冷媒の流れは暖房時の流れである。関連技術として熱交換器出口のガス冷媒配管１０に温度センサを設置し、この温度センサによって測定した温度Ｔ１０の値を用いて凍結保護を行う方法がある。しかし、運転中に水の供給が無くなった場合には、図４に示すように、水の供給が無くなったと同時に冷媒温度と水温は下がっていくが、ガス管温度Ｔ１０はすぐには下がらず遅れて下がりだすため、うまく凍結保護ができない。これは、プレート式熱交換器の内部構造の特徴として上部がガスになり易いこと、及び蒸発能力に合わせて室外膨張弁の開度が調整され、熱交換器出口の冷媒を一定過熱度のガスに制御するためである。水が供給されなくなった場合は、蒸発能力が低下するため、室外膨張弁５の開度は小さくなり冷媒循環量が低下する。プレート式熱交換器内の液の上昇速度が抑えられるため、ガス管温度Ｔ１０はすぐには低下しない。そのため、ガス管温度Ｔ１０の低下によって水の凍結を判定しようとする場合、ガス管温度Ｔ１０が低下を始めた頃には既に冷媒温度はマイナスとなっており、水は凍結している。 Next, the freeze protection method of the present embodiment will be described. FIG. 3 shows a plate heat exchanger 4 and its surroundings. The flow of the refrigerant is a flow during heating. As a related technique, there is a method in which a temperature sensor is installed in the gas refrigerant pipe 10 at the outlet of the heat exchanger, and freeze protection is performed using the value of the temperature T10 measured by the temperature sensor. However, when the supply of water is lost during operation, as shown in FIG. 4, the refrigerant temperature and the water temperature decrease at the same time as the supply of water is stopped, but the gas pipe temperature T10 does not decrease immediately but is delayed. As a result, the freeze protection cannot be performed well. This is because the internal structure of the plate heat exchanger tends to be gas at the top, and the opening of the outdoor expansion valve is adjusted according to the evaporation capacity, and the refrigerant at the outlet of the heat exchanger is changed to a gas with a certain degree of superheat. This is because it is controlled. When water is no longer supplied, the evaporation capacity is reduced, so the opening degree of the outdoor expansion valve 5 is reduced and the refrigerant circulation rate is reduced. Since the rising speed of the liquid in the plate heat exchanger is suppressed, the gas pipe temperature T10 does not decrease immediately. Therefore, when it is determined that the water is frozen due to the decrease in the gas pipe temperature T10, the refrigerant temperature is already negative when the gas pipe temperature T10 starts to decrease, and the water is frozen.

そこで、本実施例ではプレート式熱交換器４の側面の所定の位置に温度センサ９を設置し、その温度センサ９で測定した温度Ｔ９によって凍結保護を行う。プレート式熱交換器４はステンレス等からなる薄いプレート状の熱交換器を幾層にも重ねて、水の流れるプレートと冷媒の流れるプレートとを交互にするため、プレート式熱交換器４の側面は、水の流れるプレート及び冷媒の流れるプレートとがむきだしになっており、温度センサ９は両方のプレートと接触するように設置される。従って、温度センサ９は水と冷媒の温度影響を受ける面に設置され、水と冷媒の両方を反映した温度を測定している。水が流れている時は、水は冷媒と熱交換し、Ｔ９は水に近い温度となる。水の供給が無くなると冷媒の温度に近づいていくので、水の供給が無くなったと同時に、冷媒温度及び水温と同様にＴ９も下がっていく。この場合の温度変化を図５に示す。Ｔ９が所定の値、例えば２℃にまで低下したら運転を停止するようにすれば、冷媒よりも温度の高い水の温度はマイナスになることがなく、水の凍結を防止できる。 Therefore, in this embodiment, a temperature sensor 9 is installed at a predetermined position on the side surface of the plate heat exchanger 4, and freeze protection is performed by the temperature T9 measured by the temperature sensor 9. The plate-type heat exchanger 4 is formed by stacking thin plate-like heat exchangers made of stainless steel or the like in layers, so that the water-flowing plates and the refrigerant-flowing plates are alternated. Are exposed to a plate through which water flows and a plate through which refrigerant flows, and the temperature sensor 9 is placed in contact with both plates. Therefore, the temperature sensor 9 is installed on the surface affected by the temperature of the water and the refrigerant, and measures the temperature reflecting both the water and the refrigerant. When water is flowing, the water exchanges heat with the refrigerant, and T9 has a temperature close to that of water. When the supply of water is lost, the temperature approaches the temperature of the refrigerant. At the same time as the supply of water is lost, T9 also decreases, as with the refrigerant temperature and the water temperature. The temperature change in this case is shown in FIG. If the operation is stopped when T9 falls to a predetermined value, for example, 2 ° C., the temperature of water having a temperature higher than that of the refrigerant does not become negative, and the freezing of water can be prevented.

正常に水の供給がある場合には保護停止させず、水の供給が無い場合のみ、更に正確に保護停止させるため、温度センサ９の高さ方向の位置を説明する。 The position of the temperature sensor 9 in the height direction will be described in order to stop the protection more accurately only when there is no normal water supply, and without stopping the protection.

図６に温度センサ取付面の位置を示す。取付面はプレート式熱交換器４を実機搭載した状態で、冷媒入口ノズル２７と冷媒出口ノズル２８のある面と垂直となる鉛直方向の面である。この面は水と冷媒が交互に流れており、水と冷媒の両方が反映された温度を測ることができる。本実施例では、プレート式熱交換器４の高さ方向の全長（Ｈ）の半分（Ｈ／２）より下側であって、冷媒入口ノズル２７より上側の範囲とする。図６に示すように、斜線部分の二面とする。 FIG. 6 shows the position of the temperature sensor mounting surface. The mounting surface is a vertical surface that is perpendicular to the surface on which the refrigerant inlet nozzle 27 and the refrigerant outlet nozzle 28 are provided in a state where the plate heat exchanger 4 is actually mounted. On this surface, water and refrigerant flow alternately, and it is possible to measure the temperature reflecting both water and refrigerant. In the present embodiment, the plate-type heat exchanger 4 has a range below the half (H / 2) of the total length (H) in the height direction and above the refrigerant inlet nozzle 27. As shown in FIG. 6, it is assumed that there are two hatched portions.

図７にプレート式熱交換器４の高さ方向をＡ〜Ｄ部に分け、熱交換器内の冷媒状態を示す。状態Ｉは正常に水の供給が行われている時の状態である。状態IVは水の供給が止まった状態であり、熱交換器内の水が凍り始める直前の状態を示す。 FIG. 7 shows the refrigerant state in the heat exchanger by dividing the height direction of the plate heat exchanger 4 into A to D parts. State I is a state when water is normally supplied. State IV is a state in which the supply of water has stopped, and shows a state immediately before the water in the heat exchanger begins to freeze.

Ａ部は冷媒の状態が常にガスとなる箇所であり、プレート式熱交換器４の上部と冷媒出口ノズル２８の付近で、ガス冷媒配管１０を含む。Ｂ部は冷媒の状態が常に気液二相となる箇所である。Ｃ部は冷媒の状態が状態Ｉにおいては二相であり、状態IVでは液となる箇所である。熱交換器全長Ｈの略半分より下であって冷媒入口ノズル２７の上側までとする。Ｄ部は冷媒の状態が常に液となり、冷媒入口ノズル２７の上側から熱交換器最下部までであり、冷媒の入口である液冷媒配管１１を含む。本実施例では暖房運転時のサイクルを説明するため、冷媒入口ノズル２７と冷媒出口ノズル２８としているが、冷房運転時は冷媒入口ノズル２７から冷媒が流出し、冷媒出口ノズル２８からプレート式熱交換器４に冷媒が流入するものである。 Part A is a part where the state of the refrigerant is always gas, and includes the gas refrigerant pipe 10 near the upper part of the plate heat exchanger 4 and the refrigerant outlet nozzle 28. Part B is where the refrigerant is always in a gas-liquid two phase. Part C is a part where the state of the refrigerant is two-phase in state I and becomes liquid in state IV. It is below approximately half of the total length H of the heat exchanger and up to the upper side of the refrigerant inlet nozzle 27. The portion D includes a liquid refrigerant pipe 11 which is always in a liquid state and is from the upper side of the refrigerant inlet nozzle 27 to the lowermost part of the heat exchanger and is an inlet of the refrigerant. In this embodiment, the refrigerant inlet nozzle 27 and the refrigerant outlet nozzle 28 are used to describe the cycle during the heating operation. However, during the cooling operation, the refrigerant flows out of the refrigerant inlet nozzle 27 and plate type heat exchange from the refrigerant outlet nozzle 28. The refrigerant flows into the vessel 4.

プレート式熱交換器は流れ方向の断面積が大きいため、冷媒の流速が遅くなる。冷媒が下から上に流れるため、二相冷媒中の液冷媒は上に昇りにくく、ガス冷媒と分離して液冷媒だけが下部に溜まりやすい。更に内容積が非常に小さいために、蒸発しきれない冷媒が流れてくると熱交換器が瞬時に液冷媒で満たされてしまう。液冷媒で満たされると更に蒸発性能が落ち、回復できなくなる。そうならないために、室外膨張弁は熱交換器出口の配管の温度を監視し、蒸発しきれるだけの冷媒を流すために開度を調整している。本実施例ではこのプレート式熱交換器の特徴を利用している。状態IVでは水の供給が無くなり蒸発能力が得られなくなったために、蒸発できない冷媒が増えてプレート式熱交換器４の下部に溜まっていく。室外膨張弁５が動かなければすぐにプレート式熱交換器４の上部まで液が溜まりＡ部まで二相又は液冷媒で満たされるが、実際には室外膨張弁５を閉めて冷媒流量を少なくする制御を行う。これによりＡ部はしばらくの間ガス冷媒で満たされ温度が下がらない。Ｃ部は状態Ｉにおいては気液二相であり、状態IVでは液冷媒で満たされるため、温度が急激に低下する。本実施例ではこのＣ部に温度センサ９を設置し、温度センサ９の値が所定の値を下回ったら運転を停止する。 Since the plate heat exchanger has a large cross-sectional area in the flow direction, the flow rate of the refrigerant is slow. Since the refrigerant flows from the bottom to the top, the liquid refrigerant in the two-phase refrigerant is unlikely to rise upward, and is separated from the gas refrigerant and only the liquid refrigerant is likely to accumulate in the lower part. Furthermore, since the internal volume is very small, when the refrigerant that cannot be evaporated flows, the heat exchanger is instantaneously filled with the liquid refrigerant. When it is filled with liquid refrigerant, the evaporation performance further deteriorates and cannot be recovered. In order to prevent this, the outdoor expansion valve monitors the temperature of the pipe at the outlet of the heat exchanger, and adjusts the opening degree so that the refrigerant can be evaporated. In this embodiment, the feature of the plate heat exchanger is used. In the state IV, the supply of water is lost and the evaporation ability cannot be obtained. Therefore, the refrigerant that cannot be evaporated increases and accumulates in the lower part of the plate heat exchanger 4. If the outdoor expansion valve 5 does not move, the liquid immediately accumulates up to the upper part of the plate heat exchanger 4 and fills up to part A with two-phase or liquid refrigerant, but actually the outdoor expansion valve 5 is closed to reduce the refrigerant flow rate. Take control. Thereby, A part is filled with gas refrigerant for a while, and temperature does not fall. Part C is a gas-liquid two-phase in state I, and is filled with liquid refrigerant in state IV, so the temperature drops rapidly. In the present embodiment, the temperature sensor 9 is installed in the portion C, and the operation is stopped when the value of the temperature sensor 9 falls below a predetermined value.

状態IVにおいてＣ部の表面温度が急激に低下する理由を説明する。
図８に水と冷媒が温度センサ９に与える影響を示す。例として、状態Ｉにおける熱交換器内の冷媒温度を１℃、水温を９℃とし、状態IVにおける熱交換器内の冷媒温度を０℃、水温を８℃とする。温度センサ９を設置する熱交換器の表面温度は、内部の冷媒と水に影響される。まず状態Ｉでは冷媒は気液二相である。水の供給が無くなった状態IVでは、冷媒は液となる。液冷媒は二相冷媒より熱容量が大きくなる。更に水が止まるため、水の熱伝達率が低下する。この状態では、熱交換器の表面温度は冷媒側の温度に大きく影響され、冷媒の温度に近くなる。以上の特性によりＣ部は水の供給が無くなった時に大きく温度が低下する。 The reason why the surface temperature of the part C rapidly decreases in the state IV will be described.
FIG. 8 shows the influence of water and refrigerant on the temperature sensor 9. As an example, the refrigerant temperature in the heat exchanger in state I is 1 ° C., the water temperature is 9 ° C., the refrigerant temperature in the heat exchanger in state IV is 0 ° C., and the water temperature is 8 ° C. The surface temperature of the heat exchanger in which the temperature sensor 9 is installed is affected by the internal refrigerant and water. First, in state I, the refrigerant is a gas-liquid two phase. In the state IV in which the supply of water is lost, the refrigerant becomes a liquid. Liquid refrigerant has a larger heat capacity than two-phase refrigerant. Furthermore, since water stops, the heat transfer rate of water falls. In this state, the surface temperature of the heat exchanger is greatly influenced by the temperature on the refrigerant side, and is close to the temperature of the refrigerant. Due to the above characteristics, the temperature of the part C greatly decreases when the supply of water is lost.

プレート式熱交換器４のＡ〜Ｄ部の温度を状態別に示したものを図９に示す。
凍結保護する所定の温度（保護値）を定め、これを破線で示す。状態ＩとIIは正常に水が供給されている場合であり、ここで保護がかかってはいけない。
状態Ｉはプレート式熱交換器４に水が流れている定常時であり、Ａ〜Ｄ部のどこも保護値より高い温度を示し保護停止しない。
状態IIは過渡時を示す。空調機は運転開始や負荷変動が起こると低圧圧力が一時的に下がることがあり、低圧圧力が下がると冷媒温度も下がる。特に、ビル等に用いられる多室型の空調機のように馬力が必要なものの場合は負荷変動が起こりやすい。本実施例では、空調機の負荷変動が大きい場合を過渡時とする。Ａ〜Ｃ部で温度測定する場合は、水が供給されておりガス又は二相冷媒が存在し、水温の影響を大きく受けているため温度はそれほど下がらない。しかしＤ部の冷媒は、液又は乾き度が低く液に近い冷媒が存在し、水温より冷媒温度の影響を受けるため、保護値を下回る温度まで冷媒の温度が下がった場合は、水が供給されているにもかかわらず保護停止してしまう。 FIG. 9 shows the temperatures of the A to D portions of the plate heat exchanger 4 according to the state.
A predetermined temperature (protection value) for freeze protection is determined, and this is indicated by a broken line. States I and II are when water is being supplied normally and should not be protected here.
State I is a steady state in which water is flowing through the plate heat exchanger 4, and any part of the parts A to D shows a temperature higher than the protection value and does not stop protection.
State II shows a transient state. In the air conditioner, the low-pressure pressure may temporarily decrease when the operation starts or the load fluctuates, and the refrigerant temperature also decreases when the low-pressure pressure decreases. In particular, when a horsepower is required, such as a multi-room type air conditioner used in a building or the like, load fluctuations are likely to occur. In the present embodiment, the case where the load fluctuation of the air conditioner is large is regarded as a transition time. When the temperature is measured in the parts A to C, water is supplied, gas or two-phase refrigerant is present, and the temperature is not greatly lowered because it is greatly affected by the water temperature. However, the refrigerant in part D is liquid or has a low dryness and is close to liquid, and is affected by the refrigerant temperature rather than the water temperature. Therefore, when the refrigerant temperature falls below the protection value, water is supplied. Despite being protected, the protection stops.

状態IIIとIVは水の供給が無い場合であり、ここでは保護停止する必要がある。
状態IIIは水が供給されていない状態で起動した場合を示す。この場合、Ａ部とＢ部は温度が下がるものの保護値まで下がるかどうかは確実ではなく、保護停止しないおそれがある。
状態IVは運転中に水の供給が無くなった場合を示す。この場合、図４及び図７で説明した通り、Ａ部の温度はほとんど下がらず、Ｂ部の温度も保護値に達するほど下がらない。一方、Ｃ部とＤ部は液冷媒が満たされることにより温度が急激に低下する。 States III and IV are cases where there is no supply of water, and protection must be stopped here.
State III shows a case where the apparatus is started in a state where water is not supplied. In this case, it is not certain whether the A part and the B part are lowered to the protection value although the temperature is lowered, and the protection may not be stopped.
State IV indicates a case where water supply is lost during operation. In this case, as described with reference to FIGS. 4 and 7, the temperature of the A portion hardly decreases, and the temperature of the B portion does not decrease so as to reach the protection value. On the other hand, the temperature of the C part and the D part rapidly decreases when the liquid refrigerant is filled.

以上より水が供給されている時は保護停止せず、水の供給が無くなった時のみそれを正確に検知して保護停止できるのはＣ部となる。本実施例ではこの特性を利用してＣ部に温度センサ９を設置し、凍結保護を行う。プレート式熱交換器４の半分の高さ位置であって、液冷媒が流入する冷媒入口ノズル２７より上の位置であるＣ部を説明したが、水が供給されている場合は気液二相となる領域であって、水が供給されなくなった場合は液冷媒が溜まる領域であればよい。 From the above, the protection is not stopped when water is supplied, but only when the water supply is lost, it can be accurately detected and the protection stopped. In the present embodiment, the temperature sensor 9 is installed in the C part by utilizing this characteristic, and freeze protection is performed. The part C, which is a half height position of the plate heat exchanger 4 and above the refrigerant inlet nozzle 27 into which liquid refrigerant flows, has been described. When water is supplied, the gas-liquid two-phase The region may be a region where liquid refrigerant accumulates when water is no longer supplied.

なお、多室型空調機の場合は、負荷変動が大きい過渡時（状態II）を考慮しなければならないため、温度センサ９の適切な設定場所は上述の通りＣ部となる。しかし、例えば室内機が１台しかなく負荷変動が小さい場合は、状態IIになりにくいため、Ｄ部であっても通水時は保護値を下回ることがない。従って、Ｄ部に温度センサ９を設けてもよい。 In the case of a multi-room type air conditioner, since a transient state (state II) where the load fluctuation is large must be taken into consideration, an appropriate setting location of the temperature sensor 9 is the C section as described above. However, for example, when there is only one indoor unit and the load fluctuation is small, it is difficult to become the state II. Therefore, you may provide the temperature sensor 9 in D part.

また、Ｃ部の温度センサ９を用いて圧縮機の運転開始前に規定の温度範囲の水が供給されているかを検知して、規定範囲外であれば運転を開始しないようにすることで、予めプレート式熱交換器４を凍結から保護することもできる。 In addition, by detecting whether the water in the specified temperature range is supplied before starting the operation of the compressor using the temperature sensor 9 of the C part, if it is out of the specified range, the operation is not started. It is also possible to protect the plate heat exchanger 4 from freezing in advance.

図１０に本実施例の凍結保護の制御を説明するフローチャートを示す。まず、圧縮機起動前に規定の温度範囲の水が供給されているかどうかを判定する（Ｓ１）。水の温度が低く、使用範囲外であれば運転を開始しない。使用範囲内であれば運転を開始する（Ｓ２）。 FIG. 10 shows a flowchart for explaining the control of freeze protection according to the present embodiment. First, it is determined whether water in a specified temperature range is supplied before starting the compressor (S1). Operation is not started if the temperature of the water is low and out of range. If it is within the use range, the operation is started (S2).

運転開始直後に、凍結防止のための保護値を下回った積算時間を把握するために、時間計測を開始する（Ｓ４）。次に、水が凍結しているかどうかを判断するために温度Ｔ９を測定し、それが所定の値、つまり保護値を下回ったかどうかを判定する（Ｓ５）。保護値は例えば２℃等に設定される。所定の温度以上であった場合は時間計測をリセット（Ｓ３）して時間計測を再度開始し（Ｓ４）、運転を継続する。Ｔ９が所定の温度以下であった場合は、その状態が連続して続いているかどうかを判定するために、Ｓ３で開始した時間計測が所定時間経過したかどうかを判定する（Ｓ６）。これによりＴ９が所定温度以下、且つ所定時間経過した場合に運転を停止する（Ｓ７）。保護値を下回る温度がしばらく続いた場合に運転停止を判断するため、誤検知した場合や一時的に想定外の冷媒温度低下があった場合に、水が供給されているにもかかわらず保護停止してしまうのを防止することができる。 Immediately after the start of operation, time measurement is started in order to grasp the accumulated time that is below the protection value for preventing freezing (S4). Next, the temperature T9 is measured to determine whether or not the water is frozen, and it is determined whether or not it is below a predetermined value, that is, a protection value (S5). The protection value is set to 2 ° C., for example. If the temperature is equal to or higher than the predetermined temperature, the time measurement is reset (S3), the time measurement is started again (S4), and the operation is continued. When T9 is equal to or lower than a predetermined temperature, it is determined whether or not the time measurement started in S3 has passed a predetermined time in order to determine whether or not the state continues continuously (S6). Thus, the operation is stopped when T9 is equal to or lower than the predetermined temperature and a predetermined time has elapsed (S7). In order to judge the operation stop when the temperature below the protection value continues for a while, the protection is stopped even if water is supplied in the case of erroneous detection or when the temperature of the refrigerant temporarily falls unexpectedly. Can be prevented.

１室外機
２圧縮機
３四方弁
４熱源側熱交換器（プレート式熱交換器）
５室外膨張弁
６受液器
７高圧圧力センサ
８低圧圧力センサ
９温度センサ
１０ガス冷媒配管
１１液冷媒配管
１５水配管
２０制御部
２１ガス接続配管（冷媒配管）
２２液接続配管（冷媒配管）
２３室内機
２４室内膨張弁
２５室内熱交換器
２６室内送風機
２７冷媒入口ノズル
２８冷媒出口ノズル 1 Outdoor unit 2 Compressor 3 Four-way valve 4 Heat source side heat exchanger (plate type heat exchanger)
5 Outdoor expansion valve 6 Liquid receiver 7 High pressure sensor 8 Low pressure sensor 9 Temperature sensor 10 Gas refrigerant pipe 11 Liquid refrigerant pipe 15 Water pipe 20 Control unit 21 Gas connection pipe (refrigerant pipe)
22 Liquid connection piping (refrigerant piping)
23 Indoor unit 24 Indoor expansion valve 25 Indoor heat exchanger 26 Indoor blower 27 Refrigerant inlet nozzle 28 Refrigerant outlet nozzle

Claims

水が流れる第１プレートと冷媒が流れる第２プレートとを有するプレート式熱交換器、圧縮機、室外膨張弁、を備える室外機と、室内熱交換器を備える室内機とを冷媒配管で接続した空気調和機において、
前記プレート式熱交換器の冷媒入口ノズルと冷媒出口ノズルのある面と垂直となる鉛直方向の面において前記プレート式熱交換器の高さ方向の略中心より下側であって、前記冷媒入口ノズルより上側に温度センサを備え、
前記第１プレートの水と前記第２プレートの冷媒との両方を反映した温度を前記温度センサで測定し、前記温度センサの値が所定の値以下となる場合に前記圧縮機の運転を停止することを特徴とする空気調和機。 A plate heat exchanger having a first plate through which water flows and a second plate through which refrigerant flows, an outdoor unit including a compressor and an outdoor expansion valve, and an indoor unit including an indoor heat exchanger are connected by a refrigerant pipe. In air conditioner,
The refrigerant inlet nozzle that is below the approximate center in the height direction of the plate heat exchanger in a vertical plane perpendicular to the plane of the refrigerant inlet nozzle and the refrigerant outlet nozzle of the plate heat exchanger. A temperature sensor on the upper side,
The temperature that reflects both the water in the first plate and the refrigerant in the second plate is measured by the temperature sensor, and the operation of the compressor is stopped when the value of the temperature sensor falls below a predetermined value. An air conditioner characterized by that.

水が流れる第１プレートと冷媒が流れる第２プレートとを有するプレート式熱交換器、圧縮機、室外膨張弁、を備える室外機と、室内熱交換器を備える室内機とを冷媒配管で接続した空気調和機において、
前記プレート式熱交換器の冷媒入口ノズルと冷媒出口ノズルのある面と垂直となる鉛直方向の面において、前記プレート式熱交換器に水が供給されている場合は気液二相冷媒が貯留する部分であって、前記プレート式熱交換器に水が供給されていない場合は液冷媒が貯留する部分に温度センサを備え、
前記第１プレートの水と前記第２プレートの冷媒との両方を反映した温度を前記温度センサで測定し、前記温度センサの値が所定の値以下となる場合に前記圧縮機の運転を停止することを特徴とする空気調和機。 A plate heat exchanger having a first plate through which water flows and a second plate through which refrigerant flows, an outdoor unit including a compressor and an outdoor expansion valve, and an indoor unit including an indoor heat exchanger are connected by a refrigerant pipe. In air conditioner,
When water is supplied to the plate heat exchanger on the surface in the vertical direction perpendicular to the surface where the refrigerant inlet nozzle and the refrigerant outlet nozzle of the plate heat exchanger are, gas-liquid two-phase refrigerant is stored. A temperature sensor in the portion where liquid refrigerant is stored when water is not supplied to the plate heat exchanger,
The temperature that reflects both the water in the first plate and the refrigerant in the second plate is measured by the temperature sensor, and the operation of the compressor is stopped when the value of the temperature sensor falls below a predetermined value. An air conditioner characterized by that.

水が流れる第１プレートと冷媒が流れる第２プレートとを有するプレート式熱交換器、圧縮機、室外膨張弁、を備える室外機と、室内熱交換器を備える室内機とを冷媒配管で接続した空気調和機において、
前記プレート式熱交換器の冷媒入口ノズルと冷媒出口ノズルのある面と垂直となる鉛直方向の面において前記プレート式熱交換器の高さ方向の略中心より下側であって、前記冷媒入口ノズルより上側に温度センサを備え、
前記圧縮機の運転開始前に前記第１プレートの水と前記第２プレートの冷媒との両方を反映した温度を前記温度センサで測定し、前記温度センサの値が所定の値以上である場合に前記圧縮機の運転を開始させることを特徴とする空気調和機。 A plate heat exchanger having a first plate through which water flows and a second plate through which refrigerant flows, an outdoor unit including a compressor and an outdoor expansion valve, and an indoor unit including an indoor heat exchanger are connected by a refrigerant pipe. In air conditioner,
A lower side of the substantially center in the height direction of Oite the plate heat exchanger in a vertical direction of the surface to be perpendicular to the surface with a coolant inlet nozzle and the refrigerant outlet nozzles of the plate heat exchanger, the refrigerant A temperature sensor is provided above the inlet nozzle ,
When the temperature sensor reflects the temperature reflecting both the water in the first plate and the refrigerant in the second plate before the compressor starts operating, and the value of the temperature sensor is equal to or higher than a predetermined value An air conditioner that starts operation of the compressor.

請求項１乃至３の何れかにおいて、前記室内機を複数備えることを特徴とする多室型の空気調和機。 4. The multi-room air conditioner according to claim 1, comprising a plurality of the indoor units.