JP2008096033A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating device capable of reducing a time necessary for a defrosting operation and immediately starting a substantial heating operation after the termination of the defrosting operation. <P>SOLUTION: This refrigerating device 20 forming a refrigerating cycle is provided with a hot gas bypass passage 13 connecting a discharge side of a compressor 1 and an upstream side of an evaporator, a hot gas bypass opening and closing valve 12 for opening and closing the hot gas bypass passage 13, and a defrost controlling means 32 performing the defrosting operation of the evaporator. Further a heat storage amount detecting means is disposed to detect a heat storage amount of piping from the compressor 1 to an expansion valve through a four-way valve 2 and a condenser, and the defrost controlling means 32 switches the four-way valve 2 to perform an inverse cycle defrosting operation when the defrosting of the evaporator is detected, and switches the four-way valve 2 to a normal cycle side when the piping heat storage amount detected by the heat storage amount detecting means becomes less than a set value, and opens the hot gas bypass opening and closing valve 12 to perform a hot gas bypass defrosting operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus that forms a refrigeration cycle, and more particularly to a refrigeration apparatus that performs a defrosting operation for melting frost adhering to an evaporator.

  In a refrigeration system such as a refrigerator or air conditioner that cools and heats a load by forming a refrigeration cycle with a compressor, four-way valve, condenser, expansion valve, evaporator, etc. It is conventionally known to perform frost operation.

In the reverse cycle defrosting operation, for example, as disclosed in Patent Document 1, when a defrosting instruction is received during the heating operation, the four-way valve is switched to the reverse cycle side, and high-temperature and high-pressure gas refrigerant is introduced into the outdoor heat exchanger. By this, it is the method of making the outdoor heat exchanger which acted as an evaporator act as a condenser, and melting frost adhering to a heat exchanger. According to this, the refrigerant that has passed through the outdoor heat exchanger is referred to as piping on the inlet side and outlet side of the indoor heat exchanger and the indoor heat exchanger before the defrosting operation (hereinafter referred to as piping on the indoor heat exchanger side). ) And is sucked into the compressor while collecting the heat accumulated.
On the other hand, as a defrosting operation different from the reverse cycle defrosting operation, for example, a hot gas bypass defrosting operation as disclosed in Patent Document 2 is also known. This is a defrosting bypass in which the compressor discharge gas refrigerant is introduced from the compressor discharge side piping of the refrigerant circuit to the liquid pipe on the inlet side of the outdoor heat exchanger that acts as an evaporator while the cycle switching means remains on the positive cycle side. In this method, a path is provided, and a part of hot gas is directly introduced into the outdoor heat exchanger to melt the attached frost.

Japanese Patent Application Laid-Open No. 2004-233015 JP-A-3-152374

  However, the two defrosting operations described in Patent Documents 1 and 2 are not sufficiently considered for reducing the time required for the defrosting operation.

  That is, the frost melting heat source during the reverse cycle defrosting operation is the electric power applied to the compressor and the heat storage accumulated in the compressor, the indoor heat exchanger, the piping on the indoor heat exchanger side, etc. In the initial stage, the heat source for melting frost can be increased using heat storage. However, if the frost does not melt completely even if all the heat stored in the indoor heat exchanger and the piping on the indoor heat exchanger side is used, the pressure on the suction side of the compressor decreases and the amount of power applied to the compressor is small. Therefore, the defrosting time becomes longer.

  In addition, when the defrosting operation is terminated and the heating operation is restarted, the piping on the indoor heat exchanger and the indoor heat exchanger side is at a low temperature. There is also a problem that a heating heat source is used to raise the temperature, and the start of substantial heating operation is delayed.

  On the other hand, the frost melting heat source during the hot gas bypass defrosting operation is only the electric power applied to the compressor and the heat storage stored in the compressor, and therefore, compared with the reverse cycle defrosting operation, the frost melting heat source is less. The defrosting operation time becomes longer.

  This invention makes it a subject to implement | achieve the freezing apparatus which suppresses the time which a defrost operation requires, and starts a substantial heating operation rapidly after completion | finish of a defrost operation.

  In order to solve the above problems, the refrigeration apparatus of the present invention is provided with a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator in a pipe for circulating a refrigerant to form a refrigeration cycle, and compression A hot gas bypass passage that connects the discharge side of the machine and the upstream side of the evaporator, a hot gas bypass on-off valve that opens and closes the hot gas bypass passage, and a defrost control means that performs a defrosting operation of the evaporator Yes. And the heat storage amount detection means which detects the heat storage amount of the piping from the compressor to the expansion valve through the four-way valve and the condenser is provided, and when the defrost control means detects the frost formation of the evaporator, the four-way valve is switched. Reverse cycle defrosting operation is performed, and when the heat storage amount detected by the heat storage amount detection means falls below the set value, the four-way valve is switched to the forward cycle side and the hot gas bypass on / off valve is opened to perform hot gas bypass defrosting operation. It is characterized by performing.

  That is, at the start of the defrosting operation, the reverse cycle defrosting operation is performed, and the heat storage of the indoor heat exchanger that originally acted as a condenser or the indoor heat exchanger side pipe (the condenser side pipe) is used. Therefore, the frost melting heat source can be increased as compared with the hot gas bypass defrosting operation. This heat storage gradually decreases as the defrosting operation is continued, but the heat storage amount detection means detects the heat storage amount of the pipe from the compressor to the expansion valve through the four-way valve and the condenser, and the detection value is set. If it falls below the value, the reverse cycle defrosting operation is switched to the hot gas bypass defrosting operation. Accordingly, when the frost is not completely melted even if the heat storage available for defrosting is used up, it is possible to reduce the overall time of the defrosting operation by switching to a more efficient hot gas bypass defrosting operation. . Moreover, since the hot gas bypass defrosting operation circulates the refrigerant on the positive cycle side, when the defrosting operation is finished and the heating operation is restarted, the indoor heat exchanger and the piping on the indoor heat exchanger side are warmed. Thus, substantial heating operation can be started quickly.

  In this case, the heat storage amount detection means can be a temperature detection means for detecting the temperature of the pipe from the compressor to the expansion valve via the four-way valve and the condenser, and from the compressor to the four-way valve and the condenser. It can also be set as the pressure detection means which detects the pressure of piping which reaches an expansion valve via. According to this, since the temperature level or pressure level is somewhat correlated with the amount of heat storage, the reverse cycle defrosting is determined by simply detecting the temperature or pressure with a sensor or the like to determine the amount of heat storage. Switching from operation to hot gas bypass defrost operation is possible.

  Furthermore, a discharge bypass passage for connecting the discharge side and the suction side of the compressor and a discharge bypass on / off valve for opening and closing the discharge bypass passage are provided. A reverse cycle defrosting operation and a hot gas bypass defrosting operation can be performed by opening the on-off valve.

  According to this, by flowing the discharge gas refrigerant through the discharge bypass passage during the reverse cycle defrosting operation and guiding it to the compressor suction side, the suction pressure is kept high and the electric input amount to the compressor is increased. Therefore, the defrosting time can be shortened. In addition, during the reverse cycle defrosting operation and the hot gas bypass defrosting operation, a large amount of liquid refrigerant returns to the suction side of the compressor, so there is a problem that the reliability of the compressor due to liquid compression decreases. According to the present invention, since the discharge gas refrigerant is bypassed to the compressor suction side, the degree of suction of the refrigerant on the suction side during the defrosting operation is increased, and the reliability of the compressor is improved by avoiding the risk of liquid compression. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigeration apparatus which suppresses the time which a defrost operation requires and starts a substantial heating operation rapidly after completion | finish of a defrost operation is realizable.

  Hereinafter, an embodiment of a refrigeration apparatus to which the present invention is applied will be described with reference to FIGS. In the following description, an embodiment is described using an air conditioner as an example of a refrigeration apparatus. However, the present invention is not limited to this, and various refrigeration apparatuses such as a refrigerator having cycle switching means such as a four-way valve are used. Applicable. The same functional parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a block diagram showing an overall configuration of an air conditioner according to a first embodiment of the present invention. As shown in FIG. 1, an air conditioner 20 includes an outdoor unit 40 formed by connecting a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an outdoor expansion valve 4, a liquid receiver 5 and the like with refrigerant pipes. And an indoor unit 50 formed by connecting the indoor expansion valve 6, the indoor heat exchanger 7 and the like with refrigerant pipes. The outdoor unit 40 and the indoor unit 50 are connected by a liquid connection pipe 10 and a gas connection pipe 11 via a liquid blocking valve 8 and a gas blocking valve 9.

  In the outdoor unit 40, the discharge gas refrigerant of the compressor 1 is supplied from the pipe connecting the discharge side of the compressor 1 to the four-way valve 2 to the pipe connecting the outdoor expansion valve 4 and the outdoor heat exchanger 3. A hot gas bypass passage 13 for bypassing is provided. The hot gas bypass passage 13 is provided with a hot gas bypass on-off valve 12 so that the discharged gas refrigerant of the compressor 1 flows appropriately.

  In the indoor unit 50, the temperature of the gas side piping part of the indoor heat exchanger 7 is used as a heat storage amount detecting means for detecting the heat storage amount accumulated in the indoor heat exchanger 7, the liquid connection pipe 10, the gas connection pipe 11, and the like. A pipe temperature thermistor 14 to be detected is attached. However, the pipe temperature thermistor 14 may be provided in the liquid side pipe part of the indoor heat exchanger 7.

  The output signal of the pipe temperature thermistor 14 is taken into the defrost control means 32 and compared with a value (for example, 0 ° C.) preset in the defrost control means 32. The comparison result is sent to the four-way valve switching means 30 and the on-off valve driving means 31. The four-way valve switching means 30 is connected to the driving device for the four-way valve 2, and the on-off valve driving means 31 is connected to the driving device for the hot gas bypass on-off valve 12.

  Next, the operation mode of the refrigeration cycle of the air conditioner of the present invention will be described. The solid line arrows shown in FIG. 1 indicate the refrigerant flow during the heating operation and the hot gas bypass defrosting operation, and the broken line arrows indicate the refrigerant flow during the reverse cycle defrosting operation. During the heating operation, the high-temperature and high-pressure refrigerant compressed by the compressor 1 passes through the four-way valve 2 and the gas blocking valve 9 and flows into the indoor heat exchanger 7, and air and heat passing through the indoor heat exchanger 7. It is exchanged to be condensed and liquefied, and flows into the indoor expansion valve 6.

  Then, the indoor expansion valve 6 adjusts the refrigerant supercooling amount at the outlet of the indoor heat exchanger 7 so as to become a certain constant value, passes through the liquid blocking valve 8 and is sent to the liquid receiver 5, and becomes unnecessary in the refrigeration cycle. The liquid refrigerant is stored in the liquid receiver 5. The refrigerant sucked out from the lower part of the liquid receiver 5 and sent to the outdoor expansion valve 4 flows into the rear outdoor heat exchanger 3 that has been depressurized to a pressure at which the outdoor heat exchanger 3 can evaporate. It exchanges heat with the air passing through the vessel 3 to evaporate, passes through the four-way valve 2 and returns to the compressor 1.

  Here, when the temperature of the air passing through the outdoor heat exchanger 3 is low and the evaporation temperature of the outdoor heat exchanger 3 decreases to 0 ° C. or less, the moisture in the air becomes frost and the fin surface of the outdoor heat exchanger 3 Since it adheres to and becomes resistance of the air passing through the outdoor heat exchanger 3, the air volume of the air passing through the outdoor heat exchanger 3 is reduced, and the evaporation performance is reduced. Along with this, the amount of heat dissipated in the indoor heat exchanger 7 is also reduced, so that the heating capacity is lowered. Therefore, a defrosting operation for melting the frost in the outdoor heat exchanger 3 is performed when frost has adhered to the outdoor heat exchanger 3 to some extent.

  Hereinafter, the defrosting operation which is a characteristic part of the air conditioner of the present invention will be described. FIG. 2 is a time chart of the defrosting operation of the present embodiment. Moreover, FIG. 3 is a flowchart figure of the defrost operation of a present Example.

  As shown in FIG. 2, during the heating operation, the outdoor expansion valve 4 controls the refrigerant superheating degree on the discharge side of the compressor 1, and the indoor expansion valve 6 controls the refrigerant supercooling degree of the indoor heat exchanger 7. (Subcool control). 2 and 3, during heating operation (S0), frosting is performed by a known means such as detecting the temperature of the outdoor heat exchanger 4 or detecting the suction pressure of the compressor 1. Is detected to determine whether or not to start the defrosting operation (S1). When a defrosting operation start command is received (Yes in S1), first, the compressor operating frequency is lowered to the lowest frequency to reduce the difference between the discharge pressure and the suction pressure (S2).

  In this state, the four-way valve 2 is switched from the heating mode (forward cycle) to the cooling mode (reverse cycle), the indoor fan and the outdoor fan are stopped, and the indoor expansion valve 6 and the outdoor expansion valve 4 are predetermined in the reverse cycle defrosting operation. The reverse cycle defrosting operation is performed with the opening degree (for example, fully open or open) (S3). After switching the refrigeration cycle, in order to increase the electric input amount to the compressor 1, control is performed so as to keep the compressor operating frequency as high as possible, for example, by maximizing the compressor operating frequency (S4).

  Next, it is determined whether the indoor gas pipe temperature detected by the pipe temperature thermistor 14 attached to the gas pipe side of the indoor heat exchanger is, for example, 0 ° C. or lower (S5). The valve 2 is switched from the cooling mode (reverse cycle) to the heating mode (forward cycle), and the hot gas bypass on / off valve 12 is opened to perform the hot gas bypass defrosting operation (S6).

  During the hot gas bypass defrosting operation, the degree of refrigerant superheating on the discharge side of the compressor 1 is controlled by controlling the opening degree of the outdoor expansion valve 4, so that the temperature of the outdoor heat exchanger 3 or the suction pressure of the compressor 1 is controlled. Accordingly, it is determined whether or not to end the defrosting operation (S7). When a command to end the defrosting operation is given (Yes in S7), the hot gas bypass on-off valve 12 is closed, the outdoor expansion valve 4 and the indoor expansion valve 6 are set to the heating start initial opening degree, and the indoor fan and the outdoor fan are set as predetermined. The heating operation is resumed by operating so that the air volume of the air is output (S8, S9).

  As described above, in the present invention, the reverse cycle defrosting operation is performed in the initial stage of the defrosting operation, and the indoor heat exchanger 7, the liquid connection pipe 10, the gas connection pipe 11, and the like that have become high temperature during the heating operation. The amount of heat stored in the pipe is used to evaporate the refrigerant that is radiated and liquefied by the outdoor heat exchanger 3 and sucks it into the compressor. Therefore, when the amount of heat is large, the suction pressure of the compressor 1 can be kept high. In addition, it is possible to maintain a large amount of refrigerant circulating in the refrigeration cycle, increase the electric input amount of the compressor 1, and thus extract a large amount of frost melting heat source.

  Further, when the amount of heat stored in the pipe is reduced, the refrigerant radiated and liquefied by the outdoor heat exchanger 3 cannot be evaporated, so the suction pressure of the compressor 1 is lowered, and the amount of refrigerant circulating in the refrigeration cycle is reduced. In addition, the electric input amount of the compressor 1 is also reduced, and consequently the heat source for melting frost is reduced. In the present invention, since the pipe heat storage amount is detected by the pipe temperature thermistor 14 attached to the gas pipe side of the indoor heat exchanger 7 having a correlation with the heat storage quantity, the pipe heat storage quantity decreases and the frost melting heat source. Can be detected. In the latter half of the defrosting operation in which the amount of heat stored in the pipe is reduced, the suction pressure of the compressor 1 is increased by performing the hot gas bypass defrosting operation compared to the reverse cycle defrosting operation. It is possible to increase the amount and increase the electric input amount of the compressor 1, and consequently increase the frost melting heat source.

  In other words, by detecting the amount of heat stored in the pipe and switching the defrosting operation from the reverse cycle defrosting operation to the hot gas bypass defrosting operation according to the change in the heat storage amount, the heat source for melting frost can be maximized throughout the entire defrosting operation. And the defrosting operation can be shortened.

  In addition, since the second half of the defrosting operation is the hot gas bypass defrosting operation, the pressures in the indoor heat exchanger 7, the liquid connection pipe 10 and the gas connection pipe 11 immediately before resuming the heating operation become the pressure state on the compressor discharge side. And since the temperature of each part will also be in a high state, the rise at the time of restarting heating operation becomes quick, and substantial heating operation can be performed rapidly.

  Here, the set value of the pipe temperature thermistor 14 is not limited to 0 ° C. and can be set as appropriate. For example, when set to 3 ° C. or 5 ° C. above 0 ° C., it is possible to prevent the indoor heat exchanger 7 from being frozen during the reverse cycle defrosting operation.

  FIG. 4 is a block diagram showing the overall configuration of the air conditioner of the second embodiment of the present invention. In FIG. 4, the same reference numerals as those in FIG. In this embodiment, as a heat storage amount detection means for detecting the heat storage amount accumulated in the indoor heat exchanger 7, the liquid connection pipe 10 and the gas connection pipe 11 shown in FIG. 1, the compressor suction side correlated with the heat storage amount is used. The output of the suction pressure sensor 15 is input to the defrost control means 32 using the suction pressure sensor 15 that detects the pressure. The defrosting control means 32 compares the set value set in advance with the output value of the suction pressure sensor 15 and outputs the comparison result to the four-way valve switching means 30 and the on-off valve driving means 31. Yes. The other configuration is the same as that of the refrigeration cycle shown in FIG.

  First, when the defrost control means 32 detects the frost formation of the outdoor heat exchanger 3 acting as an evaporator during the heating operation as in the first embodiment, the four-way valve 2 is switched to perform the reverse cycle defrost operation. During the reverse cycle defrosting operation, when there is a sufficient amount of heat stored in the indoor heat exchanger 7, the liquid connection pipe 10, and the gas connection pipe 11, the suction pressure is reduced because the heat can be absorbed to evaporate the refrigerant. However, when the amount of stored heat decreases, the amount of heat absorbed decreases and the suction pressure decreases. Therefore, when the suction pressure value becomes a certain value (for example, 0.3 MPa) or less, the four-way valve 2 is switched from the cooling mode (reverse cycle) to the heating mode (forward cycle), and the hot gas bypass on-off valve 12 And control to perform hot gas bypass defrosting operation.

  Thereby, it becomes possible to draw the frost melting heat source to the maximum throughout the defrosting operation, and the defrosting operation can be shortened. Further, the suction pressure during the hot gas bypass defrosting operation represents the condensation pressure of the outdoor heat exchanger 3, and this pressure value is a saturation pressure value equal to or higher than a temperature at which frost can be melted (for example, 5 ° C.). If the hot gas bypass defrosting operation is terminated at the time, it is possible to perform the defrosting end determination and the pipe heat storage amount detection with a single sensor, and the manufacturing cost can be reduced.

  In the present embodiment, the suction pressure sensor 15 is provided in the immediate vicinity of the suction side of the compressor 1. However, the present invention is not limited to this, and the suction pressure sensor 15 may be provided in a pipe on the upstream side or downstream side of the indoor heat exchanger 7 or the like. Similarly, the problem can be solved.

  FIG. 5 is a block diagram of the overall configuration of an air conditioner according to a third embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 or 4 indicate the same components. In the present embodiment, a discharge bypass passage 17 for bypassing the gas refrigerant from the discharge side piping of the compressor 1 to the suction side piping of the compressor 1 is provided in the air conditioner shown in FIG. 1 or FIG. A discharge bypass opening / closing valve 16 is provided in 17 so that the discharge gas refrigerant of the compressor 1 flows appropriately. Since the other structure is the same as that of the air conditioner shown in FIG. 1 or FIG. 4, description is abbreviate | omitted.

  FIG. 6 is a flowchart of the defrosting operation in the present embodiment. As in the first embodiment, during the heating operation (S0), when a command to start the defrosting operation is received (Yes in S1), first, the compressor operating frequency is lowered to the lowest frequency, and the difference between the discharge pressure and the suction pressure is reduced. Decrease (S2). In this state, the four-way valve 2 is switched from the heating mode (forward cycle) to the cooling mode (reverse cycle), the indoor fan and the outdoor fan are stopped, and the indoor expansion valve 6 and the outdoor expansion valve 4 are operated in the reverse cycle defrosting operation. And a discharge bypass on / off valve 16 is also opened to perform the reverse cycle defrosting operation (S3).

  During the reverse cycle defrosting operation, in order to increase the electric input amount to the compressor 1, the compressor operating frequency is controlled to be kept as high as possible (S4). Thereafter, when the indoor gas pipe temperature detected by the pipe temperature thermistor 14 attached to the gas pipe side of the indoor heat exchanger becomes, for example, 0 ° C. or lower (Yes in S5), the four-way valve 2 is switched from the cooling mode (reverse cycle). While switching to heating mode (forward cycle), the hot gas bypass on-off valve 12 is opened to perform the hot gas bypass defrosting operation (S6).

  During the hot gas bypass defrosting operation, the degree of refrigerant superheating on the discharge side of the compressor 1 is controlled by controlling the opening degree of the outdoor expansion valve 4, and the suction pressure value detected by the suction pressure sensor is a predetermined value (for example, When the pressure reaches 5 ° C. (saturation pressure value) or more (Yes in S7), a command to end the defrosting operation is issued. In response to this, the hot gas bypass on-off valve 12 and the discharge bypass on-off valve 16 are closed, the outdoor expansion valve 4 and the indoor expansion valve 6 are set to the heating start initial opening degree, and a predetermined air volume is generated from the indoor fan and the outdoor fan. The heating operation is resumed by operating in this manner (S8, S9).

  According to the present embodiment, during the reverse cycle defrosting operation, the discharge gas refrigerant flows through the discharge bypass passage 17 and is led to the compressor suction side, whereby the suction pressure is kept high and the electric input amount to the compressor 1 is reduced. To increase. As a result, the defrosting time can be shortened. Further, during the reverse cycle defrosting operation and the hot gas bypass defrosting operation, a large amount of liquid refrigerant returns to the suction side of the compressor 1, so that the reliability of the compressor 1 due to liquid compression decreases. However, in this embodiment, since the discharge gas refrigerant is bypassed to the compressor suction side, the suction degree of the refrigerant on the suction side during the defrosting operation is increased, thereby avoiding the risk of liquid compression and the reliability of the compressor 1. Can be improved.

  Here, in Examples 1 to 3 described above, the hot gas bypass passage 13 is configured to be bypassed to a pipe connecting the outdoor expansion valve 4 and the outdoor heat exchanger 3, but as shown in FIG. It is configured to bypass to the pipe connecting the vessel 5 and the outdoor expansion valve 4, the discharge gas superheat control during the hot gas bypass defrosting operation is changed from the outdoor expansion valve 4 to the indoor expansion valve 6, and the outdoor expansion This can be achieved by using the valve 4 fully open, and does not depart from the scope of the present invention.

  In the present invention, the on-off valve is used to appropriately flow the refrigerant through the hot gas bypass passage and the discharge bypass passage. However, the flow regulating valve and the expansion valve have the same effect, and It does not take off.

1 is a block diagram showing an overall configuration of an air conditioner according to a first embodiment of the present invention. FIG. 3 is a time chart diagram of a defrosting operation of the air conditioner of the first embodiment. FIG. 3 is a flowchart of a defrosting operation of the air conditioner according to the first embodiment. It is a block diagram which shows the whole structure of the air conditioner of 2nd Example of this invention. It is a block diagram which shows the whole structure of the air conditioner of 3rd Example of this invention. It is a flowchart figure of the defrost driving | operation of the air conditioner of 3rd Example. It is a figure which shows the modification of 1st-3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Outdoor expansion valve 5 Receiver 6 Indoor expansion valve 7 Indoor heat exchanger 12 Hot gas bypass opening / closing valve 13 Hot gas bypass passage 14 Pipe temperature thermistor 15 Suction pressure sensor 16 Discharge bypass On-off valve 17 Discharge bypass passage 30 Four-way valve switching means 31 On-off valve driving means 32 Defrost control means

Claims (4)

The refrigerant circulation pipe is provided with a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator to form a refrigeration cycle, and the discharge side of the compressor and the upstream side of the evaporator A refrigeration apparatus comprising: a hot gas bypass passage that connects to the hot gas bypass passage; a hot gas bypass on-off valve that opens and closes the hot gas bypass passage; and a defrost control means that performs a defrosting operation of the evaporator.
A heat storage amount detecting means for detecting a heat storage amount of a pipe from the compressor to the expansion valve via the four-way valve and the condenser;
When the defrosting control unit detects frost formation of the evaporator, the four-way valve is switched to perform a reverse cycle defrosting operation, and when the amount of heat stored in the pipe detected by the heat storage amount detection unit becomes equal to or less than a set value. A refrigeration apparatus that switches the four-way valve to the positive cycle side and opens the hot gas bypass on-off valve to perform a hot gas bypass defrosting operation. The refrigerant circulation pipe is provided with a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator to form a refrigeration cycle, and the discharge side of the compressor and the upstream side of the evaporator A refrigeration apparatus comprising: a hot gas bypass passage that connects to the hot gas bypass passage; a hot gas bypass on-off valve that opens and closes the hot gas bypass passage; and a defrost control means that performs a defrosting operation of the evaporator.
Providing a temperature detection means for detecting the temperature of the pipe from the compressor to the expansion valve via the four-way valve and the condenser;
When the defrost control means detects the frost formation of the evaporator, the four-way valve is switched to perform a reverse cycle defrost operation, and when the pipe temperature detected by the temperature detection means falls below a set value, the four-way valve A refrigeration apparatus characterized in that the hot gas bypass defrosting operation is performed by switching the valve to the positive cycle side and opening the hot gas bypass on-off valve. The refrigerant circulation pipe is provided with a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator to form a refrigeration cycle, and the discharge side of the compressor and the upstream side of the evaporator A refrigeration apparatus comprising: a hot gas bypass passage that connects to the hot gas bypass passage; a hot gas bypass on-off valve that opens and closes the hot gas bypass passage; and a defrost control means that performs a defrosting operation of the evaporator.
A pressure detecting means for detecting a pressure of a pipe from the compressor to the expansion valve via the four-way valve and the condenser;
When the defrost control means detects the frost formation of the evaporator, the four-way valve is switched to perform a reverse cycle defrost operation, and when the pipe pressure detected by the pressure detection means falls below a set value, the four-way valve A refrigeration apparatus characterized in that the hot gas bypass defrosting operation is performed by switching the valve to the positive cycle side and opening the hot gas bypass on-off valve. A discharge bypass passage connecting the discharge side and the suction side of the compressor, and a discharge bypass opening and closing valve for opening and closing the discharge bypass passage,
The defrosting control means, when detecting frosting of the evaporator, opens the discharge bypass on-off valve to perform the reverse cycle defrosting operation and the hot gas bypass defrosting operation. 3. The refrigeration apparatus according to 3.

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