JPWO2014192053A1 - Refrigeration equipment - Google Patents

Abstract

A compressor circuit formed by connecting the compressor 1, the condenser 2, the liquid receiver 3, the electromagnetic valve 4, the expansion device 5, and the evaporator 6, and through which the combustible refrigerant circulates, and the compressor 2 The pressure sensor 9 for detecting the suction pressure value on the suction side, the defrosting heaters 7 and 12 for defrosting the evaporator 6, and at the start of defrosting of the evaporator 6, the solenoid valve 4 is closed and the pressure sensor 9 The operation of the compressor 1 is continued until the detected suction pressure value becomes equal to or less than a predetermined value necessary for ensuring safety at the time of defrosting when the flammable refrigerant is used. And deenergizing heaters 7 and 12 are energized.

Description

  The present invention relates to a refrigeration apparatus.

  In the conventional refrigeration apparatus, a defrosting heater is disposed in the lower part of the evaporator, and defrosting of the frost attached to the evaporator is performed by energizing the defrosting heater (see, for example, Patent Document 1).

Japanese Patent No. 3861240 (page 7, FIG. 6)

  In recent years, as an alternative refrigerant to replace R410A and R404A, an air conditioner or a refrigeration apparatus using a refrigerant such as R32 having a low global warming potential (GWP) value has been proposed. R32 is slightly flammable. In an air conditioner or refrigeration system using this type of flammable refrigerant, R32 is used inside an indoor unit (unit cooler in a refrigeration system) or indoor unit (unit cooler in a refrigeration system). There is concern about accidents (hereinafter referred to as “fire accidents”) in which flammable refrigerant leaks from the connected refrigerant piping (communication piping) to the outside, causing a fire, or generating toxic gas due to lack of oxygen or thermal decomposition. Is done. In particular, when a flammable refrigerant comes into contact with an open flame or a metal heated to a high temperature of 300 to 400 ° C. or higher, it may be thermally decomposed to generate a toxic gas. The toxic gas mentioned here mainly refers to hydrogen fluoride.

  A combustible refrigerant such as R32 has a property of being heavier than air. For this reason, when the defrost heater is arrange | positioned at the lower part of an evaporator like patent document 1, a refrigerant | coolant should be carried out from refrigerant piping (hairpin) of an evaporator and refrigerant piping connected to an evaporator by any chance during energization of a defrost heater. If leaks, the refrigerant may come into contact with the defrosting heater and generate toxic gas due to thermal decomposition.

  The present invention has been made to solve the above-described problems, and even if the refrigerant piping of the evaporator is damaged and flammable refrigerant leaks, it can be safely defrosted, It aims at obtaining the freezing apparatus which can prevent generation | occurrence | production of toxic gas.

  A refrigeration apparatus according to the present invention is formed by connecting a compressor, a condenser, a receiver, a solenoid valve, a throttling device, and an evaporator, a refrigerant circuit in which a flammable refrigerant circulates, and a compression Refrigerant state detection sensor that detects the refrigerant state on the suction side of the machine, a defrost heater that defrosts the evaporator, and a refrigerant that is detected by the refrigerant state detection sensor when the defrosting of the evaporator is started and the electromagnetic valve is closed The compressor operation is continued until the state quantity falls below a predetermined value required for ensuring safety during defrosting when a flammable refrigerant is used. The heater is energized.

  According to the present invention, it is possible to obtain a refrigeration apparatus that can safely perform defrosting and prevent the generation of fire and toxic gas even if the refrigerant piping of the evaporator is damaged and the flammable refrigerant leaks. it can.

It is a refrigerant circuit figure of the freezing apparatus in Embodiment 1 of this invention. It is a defrost heater control circuit diagram of the freezing apparatus in Embodiment 1 of this invention. It is a flowchart of the defrost control of the freezing apparatus in Embodiment 1 of this invention. It is a schematic perspective view of the evaporator of FIG. It is arrangement | positioning explanatory drawing of the evaporator and defrost heater of FIG. It is arrangement | positioning explanatory drawing of the evaporator and drain pan of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol shall be attached | subjected to the same part.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus in Embodiment 1 of the present invention.
In FIG. 1, a refrigeration apparatus 100 is formed by connecting a compressor 1, a condenser 2, a liquid receiver 3, a solenoid valve 4, a throttling device 5, and an evaporator 6 in series. A circulating refrigerant circuit is provided. The evaporator 6 is provided with a blower 10 that ventilates the evaporator 6. Note that a flammable refrigerant having a small global warming potential (GWP) value is used as the refrigerant. Specifically, for example, a slightly flammable refrigerant, a mixed refrigerant containing 65 wt% or more of R32 or R32, an HFO refrigerant, a propane or a refrigerant mixed with propane, or the like is used.

  In the evaporator 6, defrosting heaters 7 and 12 for defrosting and a temperature sensor 8 are arranged. The temperature sensor 8 is arrange | positioned at the vent part (U bend part, hairpin) 6c (refer FIG. 4 mentioned later) which is the copper piping of the evaporator 6, for example. Further, a pressure sensor (refrigerant state detection sensor) 9 for detecting the suction pressure is installed in the suction portion of the compressor 1.

FIG. 2 is a defrost control circuit diagram of the refrigeration apparatus in Embodiment 1 of the present invention.
In FIG. 2, the defrost control controller 11 controls the entire refrigeration apparatus and controls the defrost heaters 7 and 12 based on information from the temperature sensor 8 and the pressure sensor 9.

FIG. 3 is a flowchart of defrosting control of the refrigeration apparatus in Embodiment 1 of the present invention. Hereinafter, the operation at the time of defrosting in the refrigeration apparatus 100 will be described with reference to FIG. The control of the flowchart in FIG. 3 is performed at each control interval.
When the surface temperature of the evaporator 6 falls below 0 degrees during the operation of the refrigeration apparatus 100, moisture in the air adheres to the surface of the evaporator 6 as frost. When the frost grows until it obstructs the air path of the evaporator 6, the heat exchange between the air and the refrigerant cannot be sufficiently performed, and the capacity is reduced. Therefore, the defrosting controller 11 can evaporate during the operation of the refrigerant circuit. It is determined whether to start defrosting of the vessel 6 (S1). An arbitrary method can be adopted to determine the start of defrosting. For example, the determination is made based on the accumulated operation time of the compressor 1 (a timer built in the defrosting controller 11, not shown). That is, when the accumulated operation time of the compressor 1 exceeds a predetermined time, it is determined that defrosting is started. The determination of defrosting start is not limited to this method, and any method can be adopted.

  When the defrost control controller 11 determines to start defrosting, the solenoid valve 4 is first closed (S2), and the detected value (suction pressure value) detected by the pressure sensor 9 becomes equal to or less than the predetermined value P (S3). The operation of the compressor 1 is continued. Thereby, the flammable refrigerant in the evaporator 6 is collected in the liquid receiver 3. This predetermined value P is a value necessary for ensuring safety at the time of defrosting when a flammable refrigerant is used, and is specifically set to a value indicating a state in which almost no flammable refrigerant remains in the evaporator 6. If it does in this way, in the state where S3 was satisfied, there will be almost no flammable refrigerant in the refrigerant piping of evaporator 6.

  When the combustible refrigerant hardly exists in the refrigerant pipe of the evaporator 6 as described above, the defrost control controller 11 stops the compressor 1 and the blower 10 and energizes the defrost heaters 7 and 12 (S4). . In this way, the defrosting heaters 7 and 12 are energized after the refrigerant pipe of the evaporator 6 is almost free of flammable refrigerant, so that the refrigerant pipe of the evaporator 6 is defrosted during the defrosting of the evaporator 6. Even in the event of damage, the combustible refrigerant can be prevented from being heated by the heat of the defrost heaters 7 and 12. Therefore, defrosting can be carried out safely, and fire and toxic gas generation can be prevented.

  And the defrost control controller 11 judges whether defrosting is complete | finished (S5), and if it judges that defrosting is complete | finished, electricity supply of the defrost heaters 7 and 12 will be stopped (S6). An arbitrary method can be adopted for determining whether to end the defrosting, for example, based on the detection result of the temperature sensor 8. That is, when the detection result of the temperature sensor 8 is equal to or greater than the predetermined value T, it is determined that the defrosting is finished.

FIG. 4 is a schematic perspective view of the evaporator of FIG. In FIG. 4, the arrow direction indicates the direction of air flow. FIG. 5 is an explanatory view of the arrangement of the evaporator and the defrost heater in FIG.
The evaporator 6 includes a plurality of fins 6a stacked at intervals, a plurality of refrigerant pipes 6b penetrating the fins 6a in the stacking direction, and a vent part 6c connecting ends of the plurality of refrigerant pipes 6b. Have. The defroster heaters 7 and 12 are arranged so that the refrigerant does not directly contact the defroster heaters 7 and 12 even when the refrigerant pipe 6b of the evaporator 6 is damaged and the refrigerant leaks. That is, the defrost heater 7 is disposed on the air suction surface 6 </ b> A of the evaporator 6, and the defrost heater 12 is disposed on the air blowing surface 6 </ b> B of the evaporator 6. In some cases, the defrosting heater may be arranged only on the air suction surface 6A of the evaporator 6 (only the defrosting heater 7) or only on the air blowing surface 6B of the evaporator 6 (only the defrosting heater 12).

FIG. 6 is an explanatory view of the arrangement of the evaporator and the drain pan of FIG.
As shown in FIG. 6, a drain pan 13 that receives drain that has fallen from the evaporator 6 during defrosting is disposed below the evaporator 6. A drain pan heater 14 that warms the drain pan 13 is fixed to the drain pan 13 by a fixing bracket 15. The drain pan heater 14 has an outer surface 13a opposite to the evaporator 6 of the drain pan 13 so that the flammable refrigerant does not directly contact the drain pan heater 14 even if a refrigerant leaks from the refrigerant pipe 6b of the evaporator 6. Arranged on the side. By doing in this way, the surface temperature by the side of the inner surface 13b of the drain pan 13 during defrosting can be suppressed to 100 degrees C or less.

  The drain pan heater 14 is not limited to being disposed on the outer surface 13a side of the drain pan 13, and may be disposed on the inner surface 13b side. In this case, even if a refrigerant leak occurs from the refrigerant pipe 6b of the evaporator 6, a fixing bracket or the like that covers all the heat generating part of the drain pan heater 14 is used so that the combustible refrigerant does not directly contact the drain pan heater 14. Then, the drain pan heater 14 may be fixed to the drain pan 13. The control of the drain pan heater 14 is the same as the control of the defrost heaters 7 and 12 in the flowchart of FIG.

  As described above, at the start of defrosting, the defrosting heaters 7 and 12 are energized after the combustible refrigerant is hardly present in the refrigerant pipe 6b of the evaporator 6. For this reason, even if there is any damage from the refrigerant piping of the evaporator 6 during the defrosting of the evaporator 6, it is possible to avoid that the combustible refrigerant is heated by the heat of the defrosting heaters 7 and 12. Therefore, defrosting can be carried out safely, and fire and toxic gas generation can be prevented.

  In the above description, the predetermined value necessary for ensuring safety at the time of defrosting when the flammable refrigerant is used is the suction pressure value, but is not limited to this, and may be the evaporation temperature of the evaporator 6. .

  In addition, even if a flammable refrigerant contacts the defrosting heaters 7 and 12, the surface temperature of the defrosting heaters 7 and 12 is less than 300 ° C. in the defrosting controller 11 so that the defrosting controller 11 does not thermally decompose. You may make it control the heating amount of the defrost heaters 7 and 12 so that it may suppress to.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 3 Liquid receiver, 4 Solenoid valve, 5 Throttling device, 6 Evaporator, 6A Air suction surface, 6B Air blowing surface, 6a Fin, 6b Refrigerant piping, 6c Vent part, 7 Defrost heater , 8 Temperature sensor, 9 Pressure sensor, 10 Blower, 11 Defrost controller, 12 Defrost heater, 13 Drain pan, 13a Drain pan outer surface, 13b Drain pan inner surface, 14 Drain pan heater, 15 Fixing bracket, 100 Refrigeration equipment.

The refrigeration apparatus according to the present invention is formed by connecting a compressor, a condenser, a receiver, a solenoid valve, a throttling device, and an evaporator in series, and includes R32 or R32 in an amount of 65% by weight or more. A refrigerant circuit in which the mixed refrigerant circulates, a refrigerant state detection sensor that detects the refrigerant state on the suction side of the compressor, a defrost heater that defrosts the evaporator, and closes the solenoid valve at the start of defrosting of the evaporator The compressor operation is continued until the refrigerant state quantity detected by the refrigerant state detection sensor becomes equal to or less than a predetermined value for ensuring safety during defrosting when a flammable refrigerant is used. Then, the operation of the compressor is stopped, and a controller for energizing the defrost heater is provided, and the defrost heater is provided on one or both of the air suction surface and the air discharge surface of the evaporator provided in the unit cooler, The control device has a surface temperature of the defrost heater of less than 300 ° C. Thus, the energization amount of the defrost heater is controlled .

The refrigeration apparatus according to the present invention is formed by connecting a compressor, a condenser, a receiver, a solenoid valve, a throttling device, and an evaporator in series, and includes R32 or R32 in an amount of 65% by weight or more. A refrigerant circuit in which the mixed refrigerant circulates, a refrigerant state detection sensor that detects the refrigerant state on the suction side of the compressor, a defrost heater that defrosts the evaporator, and closes the solenoid valve at the start of defrosting of the evaporator The compressor operation is continued until the refrigerant state quantity detected by the refrigerant state detection sensor becomes equal to or less than a predetermined value for ensuring safety during defrosting when a flammable refrigerant is used. Then, the operation of the compressor is stopped and the controller for energizing the defrost heater is provided, and the defrost heater is provided only on one or both of the air suction surface and the air discharge surface of the evaporator provided in the unit cooler. The control device is designed so that the surface temperature of the defroster heater is not 300 ° C. And it controls the amount of current defrost heater so that.

Claims (6)

A refrigerant circuit that is formed by connecting a compressor, a condenser, a liquid receiver, a solenoid valve, a throttling device, and an evaporator in series, and in which a combustible refrigerant circulates;
A refrigerant state detection sensor for detecting a refrigerant state on the suction side of the compressor;
A defrost heater for defrosting the evaporator;
At the start of defrosting of the evaporator, the solenoid valve is closed, and the refrigerant state quantity detected by the refrigerant state detection sensor is equal to or less than a predetermined value for ensuring safety at the time of defrosting when a combustible refrigerant is used. A refrigeration apparatus comprising: a control device that continues the operation of the compressor until reaching a predetermined value, stops the operation of the compressor when the value is equal to or less than the predetermined value, and energizes the defrost heater. The refrigerant state detection sensor is a pressure sensor that detects an intake pressure of the compressor, and the predetermined value is an intake pressure value indicating a state in which there is almost no flammable refrigerant in the evaporator. The refrigeration apparatus according to claim 1. The refrigeration apparatus according to claim 1 or 2, wherein the defrosting heater is provided on one or both of an air suction surface and an air blowing surface of the evaporator. The said control apparatus controls the energization amount of the said defrost heater so that the surface temperature of the said defrost heater may be less than 300 degreeC, The Claim 1 characterized by the above-mentioned. Refrigeration equipment.   The refrigeration apparatus according to any one of claims 1 to 4, wherein a drain pan heater is provided on an outer surface side of the drain pan provided in the lower part of the evaporator. The refrigerating apparatus according to any one of claims 1 to 5, wherein the combustible refrigerant is R32 or a mixed refrigerant containing 65 wt% or more of R32.

Images