JP2015222145A - Air cooler, and method for operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air cooler which, when a chilled item is stored in a cooling room the air in which is cooled by CO2 refrigerant, eliminate the possibility of a large amount of frost to be attached on a CO2 refrigerant flow passage, and provide a method for operating the air cooler.SOLUTION: An air cooler 21 cools the air in a cooling room 4 by exchanging heat between a CO2 refrigerant flow passage in which CO2 refrigerant liquid in low temperature circulates and the air circulated by an electric fan 45 in the cooling room 4 storing a cooling item. The CO2 refrigerant flow passage includes a first and second refrigerant flow passages constituting a parallel flow passage in which the CO2 refrigerant liquid flows in parallel. The first and second refrigerant flow passages are arranged in different position from each other so as to be oriented in directions opposite to the flow direction of the air flowed by the fan 45 in the cooling room 4. In respective forward passages of the passages, a first open/close valve 29 and a second open/close valve 30 are provided to permit and cut off the flow of the CO2 refrigerant liquid. The first open/close valve 29 and the second open/close valve 30 are configured to flow the CO2 refrigerant liquid at the same time or in an alternate manner by opening and closing the first open/close valve 29 and the second open/close valve 30.

Description

  The present disclosure relates to an air cooler that cools CO2 cooled by a circulation path that circulates CO2 as a refrigerant with air flowing by a fan provided in a cooling chamber, and cools the air. .

  Such an air cooler that cools air using CO2 as a refrigerant is, for example, as described in Patent Document 1, a primary refrigeration cycle apparatus using NH3 as a refrigerant and a secondary refrigeration cycle apparatus using CO2 as a refrigerant. There are some which are configured with. The secondary refrigeration cycle apparatus includes a CO2 receiver that stores CO2 refrigerant liquid liquefied by heat exchange with NH3 refrigerant in the primary refrigeration cycle apparatus, a CO2 refrigerant liquid that is installed in the cooling chamber and supplied from the CO2 receiver, A CO2 refrigerant liquid channel that cools the air in the cooling chamber by exchanging heat with the air and a fan that sends the air in the cooling chamber to the air cooler are configured.

  The CO2 refrigerant liquid stored in the CO2 receiver is sent to the air cooler in the cooling chamber at −32 ° C., for example, and exchanges heat with the air in the cooling chamber flowing by the fan to cool the air in the cooling chamber (for example, − 25 ° C.). The heat-exchanged refrigerant gas returns to the CO2 receiver, is cooled and liquefied by the NH3 refrigerant of the primary refrigeration cycle apparatus, and returns to the CO2 receiver.

  As shown in FIG. 5, the air cooler 60 includes a casing 61 formed in a box shape, and a CO2 refrigerant flow path 62 that is disposed in the casing 61 and through which the cooled CO2 refrigerant liquid flows. Is done. The casing 61 is formed so that the air in the cooling chamber 4 is taken in by the electric fan 45, is brought into contact with the CO2 refrigerant flow path 62, and is discharged (see Patent Document 1).

  The CO2 refrigerant flow path 62 extends from one end portion in the width direction of the casing 61 to the other end portion in the width direction of the casing 61 along the front wall portion 61a of the casing 61, and is folded back in the opposite direction at the other end portion in the width direction. It is formed so as to meander from the front wall portion 61a to the rear side so as to extend along the wall portion, bend in the opposite direction at one end portion in the width direction, and extend along the front wall portion 61a. An electric fan 45 is disposed outside the rear wall portion 61 b of the casing 61. With the electric fan 45, the air in the cooling chamber 4 flows into the casing 61 from the front of the casing 61, flows outside the CO 2 refrigerant flow path 62, and is discharged from the rear of the casing 61. The air flowing in the casing 61 and the CO2 refrigerant flowing in the CO2 refrigerant flow path are heat-exchanged to cool the air in the cooling chamber 4.

JP2012-7757

  This conventional air cooler that cools air using CO2 as a refrigerant maintains the cooling chamber at a dew point temperature of −25 ° C. or lower, and the items stored in the cooling chamber are already frozen items such as frozen foods. Therefore, the moisture content of the stored items is small. For this reason, since the amount of moisture contained in the air sent into the air cooler by the fan is small, the moisture contained in the air condenses during the heat exchange between the CO2 refrigerant and the air in the cooling chamber, and the CO2 refrigerant liquid flow path. The amount of frost adhering to is small.

  On the other hand, there is a desire to store chilled products such as vegetables, milk and yogurt in the cooling chamber. In order to store such chilled products, the temperature in the cooling chamber needs to be in the range of + 10 ° C. to −5 ° C., and in order to increase the temperature in the cooling chamber, the liquefaction temperature of the CO 2 refrigerant liquid is increased. For example, when the temperature in the cooling chamber is set to + 5 ° C., the pressure of the CO 2 refrigerant increases and exceeds the pressure resistance of the CO 2 refrigerant circuit. Therefore, it is conceivable to set the pressure of the CO2 refrigerant so that it does not exceed the withstand pressure of the CO2 refrigerant circulation path and is equal to or lower than the allowable upper limit pressure. However, the temperature of the CO 2 refrigerant liquid corresponding to the upper limit pressure of the CO 2 refrigerant is considerably lower than the temperature in the cooling chamber (for example, −25 ° C.), and the temperature difference from the cooling chamber is increased. In addition, chilled products such as vegetables stored in the cooling chamber are rich in water. For this reason, when heat is exchanged between the air in the cooling chamber and the low-temperature CO2 refrigerant, a large amount of moisture in the air becomes frost and adheres to the CO2 refrigerant flow path.

  Therefore, the air passage that flows through the CO2 refrigerant flow path in the casing becomes clogged, and the air suction resistance by the electric fan increases, and the motor that drives the electric fan becomes overloaded. As a result, frequent defrost operation is required, and the cooling time for chilled products is shortened, resulting in poor cooling.

  In view of the above-described circumstances, at least one embodiment of the present invention can switch between an operation capable of storing a frozen product in the cooling chamber and an operation capable of storing a chilled product in the cooling chamber. When cooling the air in the cooling chamber by exchanging heat with the air in the room, when storing the chilled product in the cooling chamber, a large amount of frost adheres to the CO2 refrigerant flow path of the air cooler and the electric fan It is an object of the present invention to provide an air cooler that does not become overloaded and a method of operating the same.

An air cooler according to at least one embodiment of the present invention comprises:
An air cooler that cools the air in the cooling chamber by exchanging heat between the CO2 refrigerant flow path through which the low-temperature CO2 refrigerant liquid circulates and the air circulated by the electric fan in the cooling chamber in which the article to be cooled is stored. And
The CO2 refrigerant flow path includes a first refrigerant flow path and a second refrigerant flow path in which a CO2 refrigerant liquid flows in parallel to form a parallel flow path,
The first refrigerant flow path and the second circulation flow path are arranged at positions different from each other so as to face the flow direction of the air in the cooling chamber flowing by the fan,
A first on-off valve and a second on-off valve that allow and block the flow of the CO2 refrigerant liquid are provided in the forward path of the circulation path connected to each of the first refrigerant path and the second refrigerant path,
The first refrigerant flow path and the second refrigerant flow path are configured such that CO2 refrigerant liquid flows simultaneously or alternately by opening and closing of the first on-off valve and the second on-off valve.

  According to the air cooler, the first refrigerant flow path and the second refrigerant flow path are arranged at positions different from each other so as to face the flow direction of the air in the cooling chamber circulated by the fan. The two refrigerant channels are configured such that the cooled CO2 refrigerant liquid flows simultaneously or alternately by opening and closing the first on-off valve and the second on-off valve. For this reason, when storing a frozen product in the cooling chamber, both the first on-off valve and the second on-off valve are opened, and the CO2 refrigerant liquid is allowed to flow through the first refrigerant passage and the second circulation passage at the same time. When storing the chilled product, the first on-off valve and the second on-off valve can be alternately opened and closed to allow the CO2 refrigerant liquid to flow alternately to the first refrigerant passage and the second circulation passage. Therefore, an air cooler capable of switching between an operation capable of storing a frozen product in the cooling chamber and an operation capable of storing a chilled product in the cooling chamber can be realized. In addition, when storing chilled products in the cooling chamber, the low-temperature CO2 refrigerant liquid alternately flows in the first refrigerant flow path and the second circulation flow path, but the cooling chamber in which the CO2 refrigerant liquid flows flows by the fan. When the air comes into contact, heat is exchanged between the CO2 refrigerant liquid and the air to cool the air, and moisture in the air becomes frost and adheres to the refrigerant flow path through which the CO2 refrigerant liquid flows. On the other hand, the air in the cooling chamber flowing by the fan also contacts the refrigerant flow path where the CO2 refrigerant liquid does not flow. At this time, since the air in the cooling chamber has a temperature (for example, + 5 ° C.) at which the chilled product can be stored, frost adhering to the refrigerant flow path where the CO 2 refrigerant liquid does not flow can be melted. That is, the refrigerant flow path through which the CO2 refrigerant liquid flows makes the air in the cooling chamber a temperature at which the chilled product can be stored, and the frost adhering to this refrigerant flow path is melted by the refrigerant flow path through which the CO2 refrigerant liquid does not flow. To remove. For this reason, an air cooler in which a large amount of frost adheres to the refrigerant flow path of the air cooler during storage of the chilled product and the electric fan is not overloaded can be realized. Further, when storing chilled products, it is not necessary to stop the operation of the air cooler for the defrost operation, and the continuous operation of the air cooler is possible, thereby preventing the occurrence of poor cooling.

In some embodiments,
When the set temperature in the cooling chamber is a frozen product storage temperature zone, the first on-off valve and the second on-off valve are opened, and low temperature CO 2 is supplied to the first refrigerant passage and the second refrigerant passage. When the refrigerant liquid flows simultaneously and the set temperature in the cooling chamber is in the chilled product storage temperature zone, the first on-off valve and the second on-off valve are alternately opened and closed, and the first refrigerant flow path and the The low-temperature CO2 refrigerant liquid is configured to alternately flow through the second refrigerant flow path.

  In this case, when the set temperature in the cooling chamber is the frozen product storage temperature zone, the first on-off valve and the second on-off valve are opened. Accordingly, the low-temperature CO2 refrigerant liquid flows simultaneously in the first refrigerant flow path and the second refrigerant flow path, and the air in the cooling chamber circulated by the fan comes into contact with the first refrigerant flow path and the second refrigerant flow path and comes into CO2. Heat is exchanged between the refrigerant liquid and air to cool the air. For this reason, the temperature in the cooling chamber can be maintained in the frozen product storage temperature zone.

  On the other hand, when the set temperature in the cooling chamber is the chilled product storage temperature, the first on-off valve and the second on-off valve are alternately opened and closed. Accordingly, the low-temperature CO2 refrigerant liquid flows alternately to the first refrigerant flow path and the second refrigerant flow path, and when the air in the cooling chamber circulated by the fan contacts the refrigerant flow path through which the CO2 refrigerant liquid flows, the CO2 refrigerant liquid and While the air circulating through heat exchange with the air is cooled, moisture in the air becomes frost and adheres to the refrigerant flow path through which the CO2 refrigerant liquid flows. For this reason, the temperature in the cooling chamber can be set to a temperature range higher than the frozen product storage temperature zone, and can be maintained in the chilled product storage temperature zone by the start and stop of the fan. Since the refrigerant flow path through which the CO2 refrigerant liquid flows is either one of the first refrigerant flow path and the second refrigerant flow path, the case where CO2 flows through both the first refrigerant flow path and the second refrigerant flow path In comparison, the heat transfer area of the refrigerant flow path is halved, but the cooling capacity is not impaired because the temperature difference between the CO2 refrigerant and the air in the cooling chamber is large. In addition, the air in the cooling chamber circulated by the fan comes into contact with the refrigerant flow path through which the CO2 refrigerant liquid does not flow. At this time, since the air in the cooling chamber is at a temperature (for example, + 5 ° C.) at which the chilled product can be stored, the frost adhering to the refrigerant flow path where the CO2 refrigerant liquid does not flow can be melted by the air in the cooling chamber. it can. Therefore, when the set temperature in the cooling chamber is the chilled product storage temperature, even if frost adheres to one of the first refrigerant channel and the second refrigerant channel, the frost adhering to the other channel is removed. Therefore, frost does not attach to both the first refrigerant channel and the second refrigerant channel. Therefore, it is possible to realize an air cooler in which a large amount of frost adheres to the refrigerant flow path of the air cooler during storage of the chilled product and the electric fan is not overloaded. Moreover, it is possible to prevent overload of the motor of the fan that causes the air in the cooling chamber to flow through the first refrigerant channel and the second refrigerant channel. Further, when storing the chilled product, it is not necessary to stop the operation of the air cooler for the defrost operation, the continuous operation of the air cooler is possible, and the occurrence of poor cooling can be eliminated.

In some embodiments,
A controller for controlling opening and closing of the first on-off valve and the second on-off valve is provided;
The control device alternately opens and closes the first on-off valve and the second on-off valve at every elapse of a predetermined time when the set temperature in the cooling chamber is in a chilled product storage temperature zone. It is configured.

  In this case, when the set temperature in the cooling chamber is in the chilled product storage temperature zone, the control device alternately opens and closes the first on-off valve and the second on-off valve at every elapse of a predetermined time. Thus, the timing of opening / closing control of the first opening / closing valve and the second opening / closing valve is managed by time, so that the opening / closing control for defrosting can be facilitated.

In some embodiments,
The first refrigerant channel and the second refrigerant channel extend into the air cooler from the upstream side to the downstream side in the flow direction of the air circulated by the fan.

  In this case, since the first refrigerant flow path and the second refrigerant flow path extend in the air cooler from the upstream side to the downstream side in the flow direction of the air circulated by the fan, the set temperature is In the chilled product storage temperature zone, during the circulation of air, a large amount of frost adheres to the upstream side of the first refrigerant flow path or the second refrigerant flow, and the amount of frost attached to the downstream side decreases. For this reason, the frost can be easily melted by the air circulating in the first refrigerant flow path or the second refrigerant flow path by the fan.

An operation method of an air cooler according to at least one embodiment of the present invention includes:
2. The air in the cooling chamber is cooled by exchanging heat between the CO2 refrigerant flow path through which the low-temperature CO2 refrigerant liquid circulates and the air circulated by the electric fan in the cooling chamber in which the article to be cooled is stored. Operating method of the air cooler,
When the set temperature in the cooling chamber is a chilled product storage temperature zone, one of the first on-off valve and the second on-off valve is opened, and one of the first on-off valve and the second on-off valve With the other closed, a CO2 refrigerant liquid is allowed to flow through the circulation path through one of the first refrigerant flow path and the second circulation flow path, and the other of the first refrigerant flow path and the second circulation flow path. A first cooling step for blocking the flow of the cooled CO2 refrigerant liquid;
After the first cooling step, either the first on-off valve or the second on-off valve is opened, and either the first on-off valve or the second on-off valve is closed, and the first refrigerant A second cooling step of flowing a CO2 refrigerant liquid through one of the flow path and the second circulation flow path and blocking the flow of the CO2 refrigerant liquid through either the first refrigerant flow path or the second circulation flow path; It is comprised so that the cycle which consists of may be repeated.

  According to the operation method of the air cooler, when the set temperature in the cooling chamber is in the chilled product storage temperature zone, the CO2 refrigerant liquid is allowed to flow through one of the first refrigerant flow path and the second circulation flow path, and the first refrigerant flow After performing the first cooling step of blocking the flow of the CO2 refrigerant liquid to the other of the passage and the second circulation flow path, the cooled CO2 refrigerant liquid is caused to flow to the other of the first refrigerant flow path and the second circulation flow path, A cycle is repeated in which a second cooling step of blocking the flow of the CO2 refrigerant liquid in one of the first refrigerant channel and the second circulation channel is performed. In the first cooling step, the CO2 refrigerant liquid flows to one of the first refrigerant flow path and the second refrigerant flow path, and heat is exchanged with the CO2 refrigerant liquid to cool the air in the cooling chamber, and in the air in the cooling chamber. Moisture becomes frost and adheres to the refrigerant flow path through which the CO2 refrigerant liquid flows. For this reason, the temperature in the cooling chamber can be set to a temperature zone higher than the frozen product storage temperature, and can be maintained in the chilled product storage temperature zone by the start and stop of the fan. On the other hand, the air in the cooling chamber circulated by the fan is in contact with the other of the first refrigerant flow path and the second circulation flow path where the CO2 refrigerant liquid is not flowing. At this time, since the air in the cooling chamber is at a temperature (for example, + 5 ° C.) at which the chilled product can be stored, the frost adhering to the refrigerant flow path where the CO2 refrigerant liquid does not flow can be melted by the air in the cooling chamber. it can.

  In the second cooling step, the CO2 refrigerant liquid flows to the other of the first refrigerant flow path and the second refrigerant flow path, and heat is exchanged between the CO2 refrigerant liquid and the air to cool the cooling chamber air and Moisture in the indoor air becomes frost and adheres to the refrigerant flow path through which the CO2 refrigerant liquid flows. For this reason, the temperature in the cooling chamber can be set to a temperature zone higher than the frozen product storage temperature, and can be maintained in the chilled product storage temperature zone by the start and stop of the fan. On the other hand, the air in the cooling chamber circulated by the fan comes into contact with one of the first refrigerant flow path and the second refrigerant flow path where the flow of the CO2 refrigerant liquid is blocked. At this time, since the air in the cooling chamber is at a temperature (for example, + 5 ° C.) at which the chilled product can be stored, the frost adhering to the refrigerant flow path where the CO2 refrigerant liquid does not flow can be melted by the air in the cooling chamber. it can. Therefore, when the set temperature in the cooling chamber is the chilled product storage temperature, even if frost adheres to one of the first refrigerant channel and the second refrigerant channel, the frost adhering to the other channel is removed. Therefore, frost does not attach to both the first refrigerant channel and the second refrigerant channel. Therefore, it is possible to realize an operation method of the air cooler in which a large amount of frost adheres to the refrigerant flow path of the air cooler during storage of the chilled product and the electric fan is not overloaded.

  According to at least some embodiments of the present invention, it is possible to switch between an operation capable of storing a frozen product in the cooling chamber and an operation capable of storing a chilled product in the cooling chamber, the CO2 refrigerant liquid and the air in the cooling chamber. When the chilled product is stored in the cooling chamber by exchanging heat with the cooling chamber, a large amount of frost adheres to the CO2 refrigerant flow path of the air cooler and overloads the electric fan. The air cooler which does not become and its operating method can be provided.

It is a schematic block diagram containing the air cooler which concerns on some embodiment of this invention. It is the schematic explanatory drawing which showed the internal structure of the air cooler which concerns on some embodiment of this invention. It is explanatory drawing of the control apparatus which concerns on some embodiment of this invention. The internal structure of the air cooler which concerns on some embodiment of this invention is shown, The figure (a) and the figure (b) are the air cooler in case the set temperature in a cooling chamber is a chilled goods storage temperature zone It is a circulation state figure of the inside CO2 refrigerant liquid. It is an internal structure figure of the conventional air cooler.

  Embodiments of the present invention will be described below with reference to FIGS. 1 to 4 with reference to the accompanying drawings. First, before describing the embodiment of the operation method of the air cooler of the present invention, the embodiment of the air cooler will be described. It should be noted that the materials, shapes, relative arrangements, and the like of the components described or illustrated in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.

  Cooling temperature zones of refrigerated warehouses that store fresh foods, frozen foods, etc. at low temperatures include grades such as C grade and F grade, and the cooling temperature zones differ for each grade. For example, a Class C refrigerated warehouse is maintained in a temperature range of −10 ° C. to + 5 ° C. (hereinafter referred to as “chilled product storage temperature range”), and a Class F refrigerated warehouse is in a temperature range of −30 ° C. to −20 ° C. (Hereinafter referred to as “frozen product storage temperature zone”). In the present embodiment, an air cooler that can be switched between a chilled product storage temperature zone and a frozen product storage temperature zone will be described as an example.

  FIG. 1 shows a schematic configuration diagram of an air cooling device 1 including an air cooler according to some embodiments of the present invention. As shown in FIG. 1, the air cooling device 1 includes a primary cooling circuit 10 using NH3 as a primary refrigerant and a secondary cooling circuit 20 using CO2 as a secondary refrigerant. The secondary refrigerant CO2 is cooled by heat exchange with the primary refrigerant NH3. The secondary cooling circuit 20 is provided with an air cooler 21 that cools the air in the cooling chamber 4 by exchanging heat between the air in the cooling chamber 4 of the refrigerated warehouse 3 and the CO 2 refrigerant liquid that is the secondary refrigerant. It has been. The refrigerated warehouse 3 is provided with a cargo handling chamber 6 next to the cooling chamber 4 for performing operations such as unpacking and packing. Details of the air cooler 21 will be described later.

  The primary cooling circuit 10 includes refrigeration cycle components such as a compressor 11, a condenser 12, an expansion valve 13, and a cascade condenser 14. A cooling water circulation path 15 is connected to the condenser 12, and NH 3 condensed by the cooling water in the condenser 12 is temporarily stored in the NH 3 receiver 16, then sent to the cascade condenser 14, and the secondary refrigerant is produced in the cascade condenser 14. It is evaporated by exchanging heat with CO2. NH 3 evaporated by the cascade condenser 14 is compressed by the compressor 11 and then sent to the condenser 12. The cooling water circulation path 15 is connected to a cooling tower (not shown) provided outdoors, and the cooling water that has cooled NH 3 by the condenser 12 is cooled by the cooling tower.

  The secondary cooling circuit 20 includes a CO2 receiver 23, an air cooler 21, and the like. The CO2 receiver 23 stores the CO2 refrigerant liquid cooled and liquefied by the cascade condenser 14. The secondary cooling circuit 20 connects the CO2 circuit 24 connecting the CO2 receiver 23 and the cascade capacitor 14, and connects the CO2 receiver 23 and the air cooler 21 to send CO2 refrigerant liquid to the air cooler 21. A refrigerant supply path 25, and a CO2 refrigerant return path 26 that connects the air cooler 21 and the CO2 receiver 23 to return the CO2 refrigerant liquid (including the gas-liquid two-phase state) exchanged with the air to the CO2 receiver. Have. A CO2 refrigerant branch path 27 branched from the CO2 refrigerant supply path 25 and connected to the air cooler 21 is connected to the CO2 refrigerant supply path 25.

  The CO2 refrigerant supply path 25 and the CO2 refrigerant branch path 27 are provided with a first on-off valve 29 and a second on-off valve 30 that allow and block the circulation of the CO2 refrigerant liquid. The first on-off valve 29 and the second on-off valve 30 are electric or electromagnetic on-off valves, and the controller 40 controls the opening / closing of the first on-off valve 29 and the second on-off valve 30.

  FIG. 2 is a schematic explanatory view showing the internal structure of the air cooler 21 according to some embodiments of the present invention. As shown in FIG. 2, the air cooler 21 communicates with a casing 32 formed in a box shape and a CO2 refrigerant supply path 25 and is cooled by a refrigeration cycle of the primary cooling circuit 10 (see FIG. 1). A first refrigerant flow path 33 through which the liquid flows and a second refrigerant flow path 34 through which the CO2 refrigerant liquid that is cooled by the refrigeration cycle of the primary cooling circuit 10 communicates with the CO2 refrigerant branch path 27 are provided. That is, the first refrigerant flow path 33 and the second refrigerant flow path 34 are part of the secondary cooling circuit 20 and constitute a parallel flow path through which the CO2 refrigerant liquid flows in parallel.

  The first refrigerant flow path 33 extends from one end of the casing 32 in the width direction along the front wall portion 32a of the casing 32 toward the width direction center portion of the casing 32, and is folded back in the opposite direction at the width direction center portion. It extends along the portion 32a, is folded back in the opposite direction at one end in the width direction, and extends along the front wall portion 32a so as to meander from the front wall portion 32a to the rear side. Similarly to the first refrigerant flow path 33, the second refrigerant flow path 34 extends from the other end in the width direction of the casing 32 along the front wall portion 32 a of the casing 32 toward the center in the width direction of the casing 32. Fold back in the opposite direction at the central portion in the width direction and extend along the front wall portion 32a, fold back in the opposite direction again at the other end portion in the width direction and extend along the front wall portion 32a, and rearward from the front wall portion 32a. It is formed so as to meander toward the side.

  The front wall portion 32a and the rear wall portion 32b of the casing 32 are provided with holes (not shown) through which air can be circulated. In the casing 32, there is provided an air passage 35 that is formed around the first refrigerant passage 33 and the second refrigerant passage 34 and flows the air flowing in from the hole of the front wall portion 32a. For this reason, the air which flowed in from the hole of the front wall part 32a flows through the air path 35, and is discharged | emitted from the hole (not shown) provided in the rear wall part 32b.

  An electric fan 45 is provided on the rear side of the rear wall portion 32 b of the casing 32. As shown in FIGS. 1 and 2, the electric fan 45 is configured such that the impeller 45 b rotates by driving the motor 45 a. The electric fan 45 sucks the air in the cooling chamber 4 through the air cooler 21 and circulates in the cooling chamber 4 by driving. That is, when the electric fan 45 is driven, the air in the cooling chamber 4 passes through the hole portion of the front wall portion 32 a of the air cooler 21 and the air passage 35 in the air cooler 21, and the rear wall portion of the air cooler 21. It is discharged from the hole 32b and circulates in the cooling chamber 4. The operation of the electric fan 45 is controlled by the control device 40.

  FIG. 3 is an explanatory diagram of the control device 40 according to some embodiments of the present invention. As shown in FIG. 3, a temperature setting switch 47, a temperature sensor 48, a first on-off valve 29, a second on-off valve 30, and an electric fan 45 are electrically connected to the control device 40. The temperature setting switch 47 is a switch for setting the temperature in the cooling chamber 4, and is a chilled switch storage temperature zone (−10 ° C. to + 5 ° C.) and a frozen product storage temperature zone (−30 ° C.). ~ -20 ° C) refrigeration switch 47b is provided.

  The temperature sensor 48 detects the temperature in the cooling chamber 4. When the refrigeration switch 47b of the temperature setting switch 47 is turned ON, the control device 40 opens both the first on-off valve 29 and the second on-off valve 30, and also turns on the motor 45a (see FIG. 1) of the electric fan 45. Drive. Therefore, as shown in FIG. 2, the CO 2 refrigerant liquid flows through the first refrigerant flow path 33 and the second refrigerant flow path 34 and exchanges heat with the air in the cooling chamber 4. For this reason, the air in the cooling chamber 4 is cooled, and the inside of the cooling chamber 4 becomes the frozen product storage temperature.

  In addition, when the chilled switch 47a of the temperature setting switch 47 is turned on, the control device 40 alternately opens and closes the first on-off valve 29 and the second on-off valve 30 at predetermined time intervals, and also the motor 45a of the electric fan 45. Is started and stopped. Therefore, as shown in FIGS. 4A and 4B, the CO 2 refrigerant liquid flows alternately through the first refrigerant flow path 33 and the second refrigerant flow path 34 every predetermined time, and enters the cooling chamber 4. Exchange heat with air. For this reason, the air in the cooling chamber 4 is cooled, and the inside of the cooling chamber 4 is maintained at the chilled product storage temperature by the start and stop of the fan. The switching timing of opening and closing of the first on-off valve 29 and the second on-off valve 30 is set to the time when a predetermined time has elapsed, but the value of the current flowing through the motor 45a (see FIG. 1) of the electric fan 45 is detected and detected. When the current value exceeds a predetermined value, the opening / closing of the first opening / closing valve 29 and the second opening / closing valve 30 may be switched.

  Next, an operation method of the air cooler 21 will be described with reference to FIGS. 2, 3, and 4. FIG. 4A shows a state in which CO2 is flowing through the first refrigerant flow path 33 of the air cooler 21 when the set temperature in the cooling chamber 4 is in the chilled product storage temperature zone, and FIG. The state where CO2 is flowing through the second refrigerant flow path 34 of the air cooler 21 when the set temperature in the cooling chamber 4 is in the chilled product storage temperature zone is shown.

  First, an operation method of the air cooler 21 for setting the inside of the cooling chamber 4 to a frozen product storage temperature (for example, −25 ° C.) will be described. As shown in FIGS. 1, 2, and 3, when the refrigeration switch 47b of the temperature setting switch 47 is turned ON, the control device 40 opens both the first on-off valve 29 and the second on-off valve 30, and electrically The motor 45a of the fan 45 is driven. Accordingly, in the primary cooling circuit 10, the CO 2 refrigerant liquid flows through the CO 2 refrigerant supply path 25 through the first refrigerant flow path 33 and the second refrigerant flow path 34.

  Therefore, the CO 2 refrigerant liquid exchanges heat with the air that is sucked by the electric fan 45 and flows through the air cooler 21 during the circulation of the first refrigerant flow path 33 and the second refrigerant flow path 34. The heat-exchanged air is cooled and discharged into the cooling chamber 4, and the air discharged into the cooling chamber 4 circulates within the cooling chamber 4 and flows into the air cooler 21 again to be cooled. By such air circulation, the inside of the cooling chamber 4 is maintained at a frozen product storage temperature (for example, −25 ° C.).

  In order to maintain the temperature in the cooling chamber 4 at the frozen product storage temperature, for example, −25 ° C., the temperature of the CO 2 refrigerant liquid needs to be about −32 ° C. In this case, the temperature in the cooling chamber 4 The dew point temperature is low. Moreover, since the thing stored in the cooling chamber 4 is already frozen things, such as frozen food, there is little moisture content. For this reason, the moisture content contained in the air sent into the air cooler 21 by the electric fan 45 is small. Therefore, the amount of frost adhering to the upstream side of the first refrigerant flow path 33 and the second refrigerant flow path 34 is small during heat exchange between the CO2 refrigerant liquid and air. Therefore, an increase in air suction resistance by the electric fan 45 is suppressed, and the motor 45a of the electric fan 45 is not overloaded.

  Next, an operation method of the air cooler 21 for setting the inside of the cooling chamber 4 to a chilled product storage temperature (for example, + 5 ° C.) will be described. As shown in FIGS. 1, 3, and 4 (a), when the chilled switch 47 a of the temperature setting switch 47 is turned on, the control device 40 opens the first on-off valve 29 and opens the second on-off valve 30. Is closed and the motor 45a of the electric fan 45 is driven. Accordingly, the CO 2 refrigerant liquid from the primary cooling circuit 10 flows through the first refrigerant flow path 33 through the CO 2 refrigerant supply path 25.

  Therefore, the CO 2 refrigerant liquid exchanges heat with the air sucked by the electric fan 45 and flowing in the air cooler 21 during the circulation of the first refrigerant flow path 33, thereby cooling the air from the cooling chamber 4. The cooled air is discharged into the cooling chamber 4, circulated through the cooling chamber 4, flows into the air cooler 21 again, and is cooled. Here, the air cooler 21 has a cooling capacity capable of bringing the inside of the cooling chamber 4 to the frozen product storage temperature by flowing the CO2 refrigerant liquid through the first refrigerant flow path 33 and the second refrigerant flow path 34. doing. For this reason, when the CO2 refrigerant liquid is allowed to flow only in the first refrigerant flow path 33, the refrigerant capacity is approximately compared to the case where the CO2 refrigerant is allowed to flow in the first refrigerant flow path 33 and the second refrigerant flow path 34. Halved. Therefore, by circulating the CO2 refrigerant liquid only through the first refrigerant flow path 33, the inside of the cooling chamber 4 can be set to a temperature higher than the frozen product storage temperature, and the electric fan 45 is started and stopped to store chilled products. It can be at a temperature (eg, + 5 ° C.).

  The temperature of the CO 2 refrigerant liquid flowing through the first refrigerant flow path 33 is about −32 ° C., and chilled products such as vegetables with a large amount of water may be accommodated in the cooling chamber 4. For this reason, the absolute humidity of the air in the cooling chamber 4 increases, and the amount of moisture contained in the air sent into the air cooler 21 by the electric fan 45 increases. Therefore, when heat is exchanged between the CO2 refrigerant liquid and the air in the cooling chamber 4, the moisture contained in the air adheres as frost to the upstream side of the first refrigerant flow path 33 through which the CO2 refrigerant liquid flows. The amount increases.

  However, since the CO2 refrigerant liquid does not flow through the second refrigerant flow path 34, the air sucked into the air cooler 21 by the electric fan 45 is the second refrigerant flow path if the temperature is 0 ° C. or higher. The frost adhering to 34 can be melted. For this reason, the air path 35 around the 2nd refrigerant | coolant flow path 34 is ensured, and the overload by the increase in the attraction | suction resistance of the air by the electric fan 45 can be prevented.

  When the circulation of the CO 2 refrigerant liquid to the first refrigerant flow path 33 has passed a predetermined time, the control device 40 closes the first on-off valve 29 and opens the second on-off valve 30. The motor 45a of the electric fan 45 is maintained in a driving state. Accordingly, the CO2 refrigerant liquid from the primary cooling circuit 10 flows through the second refrigerant flow path 34 through the CO2 refrigerant supply path 25 and the CO2 refrigerant branch path 27, while circulating the CO2 refrigerant liquid to the first refrigerant flow path 33. Is cut off.

  Accordingly, the CO2 refrigerant liquid exchanges heat with the air sucked by the electric fan 45 and flowing in the air cooler 21 during the circulation of the second refrigerant flow path 34, thereby cooling the air. This cooled air is discharged into the cooling chamber 4, circulates in the cooling chamber 4, flows into the air cooler 21 again, and is cooled. Here, as described above, the air cooler 21 causes the inside of the cooling chamber 4 to reach the frozen product storage temperature by flowing the CO2 refrigerant liquid through both the first refrigerant flow path 33 and the second refrigerant flow path 34. Therefore, when the CO2 refrigerant liquid is allowed to flow only in the second refrigerant flow path 34, the refrigerant capacity is reduced to the CO2 refrigerant in the first refrigerant flow path 33 and the second refrigerant flow path 34. It will be about half that of the liquid flow. For this reason, by flowing the CO2 refrigerant liquid only through the second refrigerant flow path 34, the inside of the cooling chamber 4 can be set to a temperature higher than the frozen product storage temperature, and the chilled product storage temperature can be established by starting and stopping the electric fan 45. (For example, + 5 ° C.).

  The temperature of the CO 2 refrigerant liquid flowing through the second refrigerant flow path 34 is about −32 ° C., and the cooling chamber 4 contains chilled products such as vegetables with a large amount of water. For this reason, the absolute humidity of the air in the cooling chamber 4 increases, and the amount of moisture contained in the air sent into the air cooler by the electric fan 45 increases. Therefore, at the time of heat exchange with the CO 2 refrigerant liquid, moisture contained in the air adheres as frost on the upstream side of the second refrigerant flow path 34, and the amount of the attached frost increases.

  However, since the CO2 refrigerant liquid does not flow through the first refrigerant flow path 33, the air sucked into the air cooler 21 by the electric fan 45 is the first refrigerant flow path if the temperature is 0 ° C. or higher. The frost adhering to 33 can be melted. For this reason, the air path 35 around the 1st refrigerant | coolant flow path 33 is ensured, and the overload by the increase in the attraction | suction resistance of the air by the electric fan 45 can be prevented.

  Thus, whenever the predetermined time elapses, the control device 40 controls the opening and closing of the first on-off valve 29 and the second on-off valve 30 so that one is opened and the other is closed. The temperature of the air in the cooling chamber 4 can be cooled to the chilled product storage temperature by one of the second refrigerant flow path 34 and the other one of the second refrigerant flow path 34 and adhere to the other of the first refrigerant flow path 33 and the second refrigerant flow path 34. Frost is melted by the air in the cooling chamber 4. Therefore, it is possible to realize the air cooler 21 in which a large amount of frost adheres to the refrigerant flow path of the air cooler 21 during storage of the chilled product and the motor 45a of the electric fan 45 is not overloaded. Therefore, when storing chilled products, it is not necessary to stop the operation of the air cooler 21 and the circulation of the CO2 refrigerant liquid for the defrost operation, and the air cooler 21 can be continuously operated, resulting in poor cooling. Can be eliminated.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention. For example, the various embodiments described above may be combined as appropriate.

DESCRIPTION OF SYMBOLS 1 Air cooling device 3 Refrigerated warehouse 4 Cooling room 6 Handling room 10 Primary cooling circuit 11 Compressor 12 Condenser 13 Expansion valve 14 Cascade capacitor 15 Cooling water circulation path 16 NH3 receiver 20 Secondary cooling circuit (circulation path)
21, 60 Air cooler 23 CO2 receiver 24 CO2 circulation path 25 CO2 refrigerant supply path 26 CO2 refrigerant return path 27 CO2 refrigerant branch path 29 First on-off valve 30 Second on-off valve 32, 61 Casing 32a, 61a Front wall 32b, 61b Rear wall 33 First refrigerant flow path 34 Second refrigerant flow path 35 Air flow path 40 Control device 45 Electric fan (fan)
45a Motor 45b Impeller 47 Temperature setting switch 47a Chilled switch 47b Refrigeration switch 48 Temperature sensor 62 CO2 refrigerant flow path

Claims (5)

An air cooler that cools the air in the cooling chamber by exchanging heat between the CO2 refrigerant flow path through which the low-temperature CO2 refrigerant liquid circulates and the air circulated by the electric fan in the cooling chamber in which the article to be cooled is stored. And
The CO2 refrigerant flow path includes a first refrigerant flow path and a second refrigerant flow path in which a CO2 refrigerant liquid flows in parallel to form a parallel flow path,
The first refrigerant flow path and the second circulation flow path are arranged at positions different from each other so as to face the flow direction of the air in the cooling chamber flowing by the fan,
A first on-off valve and a second on-off valve that allow and block the flow of the CO2 refrigerant liquid are provided in the forward path of the circulation path connected to each of the first refrigerant path and the second refrigerant path,
The first refrigerant channel and the second refrigerant channel are configured such that CO2 refrigerant liquid flows simultaneously or alternately by opening and closing of the first on-off valve and the second on-off valve. Air cooler. When the set temperature in the cooling chamber is a frozen product storage temperature zone, the first on-off valve and the second on-off valve are opened, and low temperature CO 2 is supplied to the first refrigerant passage and the second refrigerant passage. When the refrigerant liquid flows simultaneously and the set temperature in the cooling chamber is in the chilled product storage temperature zone, the first on-off valve and the second on-off valve are alternately opened and closed, and the first refrigerant flow path and the The air cooler according to claim 1, wherein a low-temperature CO2 refrigerant liquid is alternately flowed through the second refrigerant flow path. A controller for controlling opening and closing of the first on-off valve and the second on-off valve is provided;
The control device alternately opens and closes the first on-off valve and the second on-off valve at every elapse of a predetermined time when the set temperature in the cooling chamber is in a chilled product storage temperature zone. It is comprised by these. The air cooler of Claim 2 characterized by the above-mentioned. The said 1st refrigerant flow path and the said 2nd refrigerant flow path are extended in the said air cooler toward the downstream from the flow direction upstream of the air circulated by the said fan. The air cooler according to any one of 1 to 3. 2. The air in the cooling chamber is cooled by exchanging heat between the CO2 refrigerant flow path through which the low-temperature CO2 refrigerant liquid circulates and the air circulated by the electric fan in the cooling chamber in which the article to be cooled is stored. Operating method of the air cooler,
When the set temperature in the cooling chamber is a chilled product storage temperature zone, one of the first on-off valve and the second on-off valve is opened, and one of the first on-off valve and the second on-off valve With the other closed, a CO2 refrigerant liquid is allowed to flow through the circulation path through one of the first refrigerant flow path and the second circulation flow path, and the other of the first refrigerant flow path and the second circulation flow path. A first cooling step for blocking the flow of the cooled CO2 refrigerant liquid;
After the first cooling step, either the first on-off valve or the second on-off valve is opened, and either the first on-off valve or the second on-off valve is closed, and the first refrigerant A second cooling step of flowing a CO2 refrigerant liquid through one of the flow path and the second circulation flow path and blocking the flow of the CO2 refrigerant liquid through either the first refrigerant flow path or the second circulation flow path; A method of operating an air cooler characterized by repeating a cycle consisting of:

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