JP2012072981A - Refrigerating method, and refrigerating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide refrigerating equipment capable of reducing construction costs and operation costs of a freezer and significantly improving operational efficiency.SOLUTION: A plurality of microchannel heat exchangers 14 are dispersively disposed in an internal upper region of the freezer 11, and a COrefrigerant liquid is circulated to the microchannel heat exchangers 14 from an NH/COrefrigerating device 12 through a COcirculation pipe 16. A forced-convection zone Zis formed in the inside upper region, and a natural convection zone Zis formed at a lower region. The outside air oa is supplied to the freezer 11 from a compartment 18 for disposal of goods through a front compartment 20. The front compartment 20 and the freezer 11 are provided with desiccant rotor-type dehumidifiers 60, 106, and dehumidification coolers 52, 100, and the outside air oa is preliminarily cooled and dehumidified in the front compartment 20, and then supplied to the freezer 11. The air is further cooled and dehumidified in the freezer 11 to keep the inside air under an amount of saturated vapor (saturated vapor partial pressure) or less.

Description

  TECHNICAL FIELD The present invention relates to a refrigeration method and a refrigeration equipment that suppresses a decrease in operating efficiency during a defrost operation and the like and that can greatly improve the operating efficiency as a whole in a refrigeration facility that stores frozen products in a freezer.

  A freezer that configures the refrigeration cycle is provided outside the freezer that stores the items to be frozen, and a heat exchanger (cooler) is provided inside the freezer to connect the refrigerator and cooler. Refrigerant piping is provided. The low-temperature refrigerant is sent from the refrigerator to the cooler, heat is exchanged between the low-temperature refrigerant and the internal air, and the internal air is cooled. Conventionally, there are many systems in which one or several large-capacity heat exchangers are installed in a large space such as a freezer warehouse. In this system, a fan with a large air volume is used to form cold air and make the internal temperature uniform. It is in operation.

In general, most of the water vapor present in the freezer is caused by intrusion of outside air by opening / closing the entrance / exit. As the refrigeration time elapses, the water vapor forms frost on the heat exchanger heat transfer surface. Therefore, it is necessary to remove frost regularly, and the refrigeration operation is interrupted and water is sprayed on the heat exchanger heat transfer surface to melt the frost, or the heat exchanger heat transfer surface is heated with a heater or the like. Heating and defrosting (defrosting operation) is performed.
Patent Document 1 discloses a defrosting apparatus using a watering system, and Patent Document 2 discloses a heating system defrosting apparatus using a heater.

  A heat exchanger called a “microchannel heat exchanger” is known as a compact and low-cost heat exchanger with good heat exchange efficiency. This heat exchanger is a heat exchanger using a flat tube in which a plurality of micro refrigerant channels are formed. A configuration example of this heat exchanger is disclosed in Patent Document 3 and Patent Document 4. Hereinafter, one structural example of this heat exchanger disclosed in Patent Document 4 will be described with reference to FIGS. 11 and 12.

  As shown in FIGS. 11 and 12, the heat exchanger 200 includes a plurality of flat tubes 206 provided between a pair of left and right headers 202 and 204, and a meandering shape between adjacent flat tubes 206 and 206. The bent fin 208 is disposed on the surface. By dividing the inside of the headers 202 and 204 by the partition member 210 at an appropriate position in the length direction, a large number of flats are formed from the refrigerant inlet 212 at the upper end of one header 202 to the refrigerant outlet 214 at the lower end of the other header 204. The tube 206 forms a refrigerant flow path.

As shown in FIG. 12, in the flat tube 206, the peripheral wall 216 has an oval cross section, and the internal space is partitioned by a plurality of partition walls 218 in the direction of the long side of the cross section to form a plurality of minute diameter refrigerant passages r. When air, which is a heat transfer medium, passes between the fins 206, heat is exchanged with the refrigerant. Heat exchange efficiency can be improved by having a wide heat transfer area between the air and the refrigerant.
Microchannel heat exchangers are widely used as vehicle radiators, car air conditioner condensers, and the like.

JP 2008-175468 A JP 2008-75963 A JP-A-2-84252 JP-A-4-20791

In the conventional refrigeration equipment, a large-capacity heat exchanger and a large air volume fan are provided, so that the construction cost and the operation cost are high, and the operation efficiency is low due to the operation requiring a large amount of power.
In addition, during the defrosting operation, the internal temperature rises due to the operation of the heater and the like, so that the operation efficiency is lowered. The watering type defrost has a problem in that it is necessary to frequently perform a defrosting operation that leads to a decrease in operating efficiency because watering or frost-dissolved water is re-diffused into the freezer in the state of water vapor or mist.

  Conventionally, since it was a refrigeration facility mainly intended to maintain a low temperature in the freezer, attention has not been paid to the behavior of water vapor in the freezer. Therefore, it has become an inefficient refrigeration system that frequently requires defrost operation.

  In view of the problems of the prior art, the present invention reduces the construction cost and the operation cost and greatly increases the operation efficiency in a refrigeration facility that keeps the inside of the freezer in an atmosphere of 0 ° C. or lower and stores the items to be frozen. An object of the present invention is to realize a refrigeration method and a refrigeration facility that can be improved greatly.

  In order to achieve such an object, the refrigeration method of the present invention removes frost adhering to the heat transfer surface of the heat exchanger and a cooling step of cooling the air in the refrigerator with a heat exchanger provided in the freezer. In a refrigeration method including a defrost process, a heat exchanger (hereinafter referred to as “microchannel”) in which a large number of minute diameter refrigerant flow paths are arranged in parallel to increase the heat transfer surface density of the flow path forming body forming the minute refrigerant flow paths. A plurality of heat exchangers are dispersedly arranged in the upper layer area in the cabinet, and natural convection in the vertical direction is formed between the heat exchanger and the inlet / outlet by a temperature difference in the vertical direction. However, the cooling step for cooling the internal air to a temperature of 0 ° C. or lower, and the water vapor in the internal air is adsorbed by the adsorbent, so that the amount of water vapor contained in the internal air is less than or equal to the saturated water vapor amount relative to the internal air temperature. By the dehumidifying step and the dehumidifying step. A defrosting step of sublimating removal frost adhering to the heat transfer surface of the heat exchanger in a low water vapor atmosphere formed Te, is made of.

  In the method of the present invention, the amount of water vapor contained in the internal air is made equal to or less than the saturated water vapor amount with respect to the internal air temperature by the dehumidifying step. By making the inside air in a low water vapor atmosphere, frost generation can be reduced and defrosting can be performed to sublimate and remove frost adhering to the heat transfer surface of the microchannel heat exchanger. The heat transfer surface density refers to the ratio of the heat transfer area to the volume of the heat exchanger.

  Therefore, it is not necessary to adopt a conventional watering method or a heating type defrosting means using a heater. As a result, water in the liquid phase, such as sprinkling water or frost melting water, is no longer present in the freezer, so there is no need for a heater for preventing re-freezing or a piping system for discharging drain water to the outside. Thus, the equipment cost can be reduced. In addition, in the defrost operation, there is no energy loss in which frost is heated and dissolved by watering, a heater, or the like, so that the operation efficiency is improved.

  Moreover, since frost formation is not heated and dissolved by watering or a heater in the defrost process, the watering or frost-dissolving water does not re-diffuse in the freezer. Therefore, since the low water vapor atmosphere in which the amount of water vapor that causes frost formation is reduced can be maintained, the frequency of the defrost operation can be reduced, and furthermore, the defrost operation itself can be made unnecessary. Further, the defrosting operation can be performed without interrupting the refrigeration operation, thereby eliminating the need for a mechanism such as an electromagnetic valve for shutting off the refrigerant for each heat exchanger.

  Thus, since the air in a store | warehouse | chamber can be hold | maintained in a low water vapor | steam atmosphere, generation | occurrence | production of dew condensation and frost formation can be suppressed on the heat-transfer surface of a heat exchanger. Therefore, even if a microchannel heat exchanger having a small-diameter refrigerant flow path is provided in the freezer, performance degradation due to condensation or frost formation can be prevented, so that the microchannel heat exchanger can be installed in the freezer. . As a result, it is not necessary to use a large-capacity heat exchanger or a large air volume fan, so that it is possible to improve operating efficiency, downsize the heat exchanger, and reduce equipment costs.

  Most of the water vapor in the freezer is due to intrusion of outside air by opening and closing the entrance. In contrast, by providing a microchannel heat exchanger in the upper layer area of the warehouse and interposing a natural convection zone between the inlet and the outlet, the amount of water vapor that causes frost formation in the upper area of the warehouse is relatively low. Can be maintained in a steam atmosphere. Thereby, frost formation on the heat exchanger heat transfer surface can be suppressed.

  In the method of the present invention, a forced convection zone that circulates the air in the cabinet between the heat exchangers is formed in the upper layer region of the chamber, and the amount of saturated water vapor or the amount close to the saturated water vapor amount is included below the upper layer region of the chamber. It is preferable to form a natural convection zone that surrounds the article to be frozen and faces in the vertical direction due to the temperature difference in the vertical direction of the air in the cabinet. In this way, by forming forced convection in the upper layer region in the warehouse where the heat exchanger is arranged, it is possible to promote frost sublimation on the heat exchanger heat transfer surface.

  In addition, the lower region in the freezer in which the product to be frozen is disposed is preferably a storage atmosphere containing a saturated water vapor amount or water vapor close to the saturated water vapor amount in terms of preventing drying of the frozen product. Therefore, in the lower region in contact with the entrance / exit, a natural convection zone containing a saturated water vapor amount or water vapor close to the saturated water vapor amount is formed by intrusion of moist air from the entrance / exit, whereby the product to be frozen can be stored in a good state.

  Furthermore, if the defrost process of the microchannel heat exchanger distributed and arranged in the upper layer area of the interior is performed at different timings, the influence of the defrost operation can be minimized and the interior temperature can always be kept constant. .

In the method of the present invention, the outside air may be precooled and preliminarily dehumidified in the front chamber arranged adjacent to the freezer, and the outside air after the precooling and preliminarily dehumidified may be introduced into the freezer.
In this way, if the outside air is precooled and preliminarily dehumidified in the front chamber, the dehumidifying and cooling process of the inside air in the freezer can be facilitated, and the dehumidifying and cooling effect in the inside can be made complete. it can.

  Moreover, the refrigeration equipment of the present invention that can be directly used for carrying out the method of the present invention is provided with a heat exchanger inside the freezer, and the heat exchanger exchanges heat between the refrigerant and the air in the refrigerator, thereby In a refrigerating apparatus for cooling, a heat exchanger in which a large number of minute diameter refrigerant flow paths are arranged in parallel to increase the heat transfer surface density of the flow path forming body forming the minute refrigerant flow paths, and water vapor of the internal air An adsorption-type dehumidifying device that adsorbs with an adsorbent and makes the amount of water vapor contained in the air in the warehouse less than or equal to the amount of saturated water vapor (saturated water vapor partial pressure) relative to the air temperature in the warehouse, and a plurality of the heat exchangers in the warehouse Dispersively arranged in the upper layer area, while cooling the internal air to a temperature of 0 ° C. or lower while forming natural convection in the vertical direction due to the temperature difference in the vertical direction between the heat exchanger and the inlet / outlet, the adsorption type In a low water vapor atmosphere formed by a dehumidifier, The frost adhering to the heat transfer surface of the exchanger is obtained by configured to sublimate removed.

  In this invention apparatus, since the said adsorption | suction type dehumidification apparatus is provided, the water vapor | steam amount which the air in a warehouse contains can be made into a saturated water vapor | steam amount or less. As a result, the generation of frost on the heat transfer surface of the heat exchanger can be reduced, and defrosting can be performed to sublimate and remove the frost attached to the heat transfer surface of the heat exchanger. Since the water vapor diffused into the chamber by sublimation can be adsorbed by the adsorption dehumidifier, the frequency of the defrost operation can be reduced, and further, the defrost operation itself becomes unnecessary.

  In addition, the equipment required for defrost operation and the piping system for water dissolved in the conventional defrost operation are not required, so the equipment cost can be reduced and the frost is heated and melted with watering or heater in the defrost operation. Since there is no energy loss to make it happen, driving efficiency improves. Furthermore, because the internal air can be maintained in a low water vapor atmosphere, even if a microchannel heat exchanger is installed in the freezer, its performance can be prevented from being reduced. This also improves operating efficiency and makes the heat exchanger compact. And equipment costs can be reduced.

  In addition, by providing a microchannel heat exchanger in the upper layer area of the warehouse and interposing a natural convection zone between the inlet and the outlet, the low water vapor atmosphere in which the amount of water vapor that causes frost formation in the upper layer area of the warehouse is relatively small Can be retained. Thereby, frost formation on the heat exchanger heat transfer surface can be suppressed.

The apparatus according to the present invention comprises forced convection forming means for circulating the air in the cabinet between the heat exchangers in the upper layer region of the chamber, and includes a saturated water vapor amount or a water vapor close to the saturated water vapor amount below the upper layer region in the warehouse. A natural convection zone that surrounds the frozen product and faces in the up-down direction due to a temperature difference in the up-down direction of the air in the refrigerator may be formed.
Thus, by forming forced convection by the forced convection forming means, sublimation of frost attached to the heat transfer surface of the heat exchanger can be promoted. In addition, a natural convection zone containing saturated water vapor or water vapor close to the saturated water vapor amount is formed in the lower region in the freezer where the products to be frozen are placed, and the product to be frozen is surrounded by an atmosphere containing the saturated water vapor content. Therefore, drying of the product to be frozen can be prevented and the product to be frozen can be stored in a good state.

In the apparatus of the present invention, a front chamber is provided adjacent to the freezer, a cooler for pre-cooling the outside air and a dehumidifier for pre-dehumidification are provided in the front chamber, and the outside air pre-cooled and dehumidified in the front chamber. May be introduced into the freezer.
This facilitates the dehumidifying and cooling operation of the internal air in the freezer, and completes the dehumidifying and cooling effect in the freezer.

  In the device of the present invention, the adsorption type dehumidifier comprises a rotary rotor carrying an adsorbent on the surface, and an adsorption process for adsorbing water vapor from the air in the chamber in one area of the rotary rotor and water vapor adsorbed in the other area. A desiccant rotor type dehumidifier that performs the desorption step of desorption simultaneously and continuously is preferable. As a result, the dehumidification step can be performed at the same time without interrupting the freezing operation, so that the product to be frozen is not disturbed.

  In the apparatus of the present invention, the forced convection forming means may be a blower that is disposed in the vicinity of the microchannel heat exchanger and forms an air flow along the heat transfer surface of the microchannel heat exchanger. Thereby, forced convection can be formed by simple and low-cost means.

  According to the method of the present invention, in a refrigeration method including a cooling step of cooling the air in the refrigerator with a heat exchanger provided in the freezer and a defrosting step of removing frost adhering to the heat transfer surface of the heat exchanger. Using a microchannel heat exchanger, a plurality of microchannel heat exchangers are distributed in the upper layer area of the cabinet, and natural convection in the vertical direction is formed between the microchannel heat exchanger and the inlet / outlet due to the temperature difference in the vertical direction. Cooling process for cooling the internal air to a temperature of 0 ° C. or lower, and water vapor in the internal air is adsorbed by the adsorbent, and the amount of water vapor contained in the internal air is saturated with respect to the internal air temperature (saturated) Dehumidification step to sublimate and remove frost adhering to the heat transfer surface of the microchannel heat exchanger in a low water vapor atmosphere formed by this dehumidification step Since the inside of the freezer has a low water vapor atmosphere and the frost on the heat exchanger heat transfer surface is removed by sublimation, the adoption of the microchannel heat exchanger and the conventional defrosting operation are stopped. Equipment COP can be greatly improved and equipment costs can be greatly reduced.

  According to the apparatus of the present invention, a microchannel heat exchanger is provided in a refrigeration facility in which a heat exchanger is provided in a freezer and the refrigerant and the air in the refrigerator are heat-exchanged by the heat exchanger to cool the air in the refrigerator. And an adsorption-type dehumidifying device that adsorbs water vapor in the interior air with an adsorbent and makes the amount of water vapor contained in the interior air equal to or less than a saturated water vapor amount (saturated water vapor partial pressure) with respect to the interior air temperature. The microchannel heat exchanger is distributed in the upper layer area of the chamber, and the natural air convection is formed between the microchannel heat exchanger and the inlet / outlet due to the temperature difference in the vertical direction, while the air in the chamber is 0 ° C or lower. And the frosting adhered to the heat transfer surface of the microchannel heat exchanger is sublimated and removed in a low water vapor atmosphere formed by the adsorption type dehumidifier. It is possible to obtain the same effect as a light method.

1 is an overall perspective view of a refrigeration facility according to a first embodiment of the method and apparatus of the present invention. It is a top view of the microchannel heat exchanger of the said refrigeration equipment. It is a front view of the microchannel heat exchanger. It is a top view of the refrigeration equipment. It is a block diagram of the desiccant rotor type dehumidifier for low dew points of the said freezing equipment. It is sectional drawing which follows the AA line in FIG. It is sectional drawing which follows the BB line in FIG. It is the block diagram which compared the operating efficiency of the freezing equipment which concerns on 1st Embodiment, and the conventional freezing equipment. It is a front view which shows another example of arrangement | positioning of the refrigeration equipment of this invention, (A) shows the time of dehumidification cooling operation, (B) shows the time of defrost operation. It is a front view which shows another example of arrangement | positioning of the refrigeration equipment of this invention. It is a front view which shows an example of a microchannel heat exchanger. It is a cross-sectional view of the flat tube of the microchannel heat exchanger of FIG.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
1st Embodiment of the method and apparatus of this invention is described based on FIGS. In the refrigeration facility 10 of the present embodiment shown in FIG. 1, an NH ₃ / CO ₂ refrigeration apparatus 12 is provided outside the freezer 11, and the NH ₃ / CO ₂ refrigeration apparatus 12 uses NH ₃ as a primary refrigerant, and NH ₃ The refrigeration cycle is configured. In the upper layer region of the freezer 10, 10 to 12 microchannel heat exchangers 14 are arranged in a plurality of, for example, 1,000 to 1,500 refrigeration ton class freezers. The NH ₃ / CO ₂ refrigeration apparatus 12 and the microchannel heat exchanger 14 are connected by a CO ₂ circulation pipe 16 including an outward path 16a and a return path 16b. Each microchannel heat exchanger 14 is connected in parallel to the forward path 16a and the backward path 16b. The microchannel heat exchanger 14 is attached above the inner surface of the side wall of the freezer 11.

From the NH ₃ / CO ₂ refrigeration apparatus 12, CO _{2 as a} secondary refrigerant is supplied to the microchannel heat exchanger 14 by the CO ₂ pump 13 via the forward path 16 a in the liquid phase. The microchannel heat exchanger 14 exchanges heat between the CO ₂ and the inside air to cool the inside air. The CO _{2 that} has become a gas phase in the microchannel heat exchanger 14 returns to the NH ₃ / CO ₂ refrigeration apparatus 12 via the return path 16b.

  The freezer 11 is provided with an entrance / exit 22 facing the cargo compartment 18, and the entrance / exit 22 is provided with an opening / closing mechanism 24 having high sealing performance as will be described later. A front chamber 20 is provided inside the freezer 10 facing the doorway 22.

  Next, the configuration of the microchannel heat exchanger 14 will be described with reference to FIGS. 2 and 3, in the microchannel heat exchanger 14, headers 32 and 34 are fixed to a frame 30 having a rectangular parallelepiped shape, and a large number of flat tubes 36 are installed between the headers 32 and 34. The flat tube 36 has a configuration similar to the configuration shown in FIG. 12, and a plurality of minute refrigerant flow paths are perforated. Further, as a means for increasing the heat transfer area, meandering bent fins 38 are arranged between the flat tubes 36 arranged in parallel. The pitch of the fins 38 is a fine interval of about 1.5 mm, for example. With this configuration, the microchannel heat exchanger 14 can dramatically increase the heat transfer surface density.

A fan 42 is attached to the support frame 40 in the vicinity of the flat tube 36. That is, the motor 44 is attached to the support frame 40, and the blades 48 of the fan 42 are attached to the rotating shaft 46 of the motor 44. By fan 42 is operated, is formed of arrow a ₁ direction of the air flow, this air flow, the flow air inside is oriented horizontally, forced convection zone Z ₁ circulating between the microchannel heat exchanger Is formed.
The lower area of the forced convection zone Z _1, the temperature difference between the upper and lower directions, natural convection zone Z ₂ to the internal air is circulated in the vertical direction (arrow a ₂ direction) is formed. As shown in FIG. 1, most of the internal space is a natural convection zone Z _2.

  A heater 49 is attached to the frame 30 on the upstream side of the flat tube 36 in the air flow direction. In the defrosting process, the heater 49 heats the ambient air around the flat tube 36 to lower the relative humidity of the ambient air and promote sublimation of frost attached to the heat transfer surface of the flat tube 36. As the heater 49, for example, a ceramic heater or the like can be used.

FIG. 4 shows the internal configuration of the freezer 10. In the figure, a plurality of microchannel heat exchangers 14 are dispersedly arranged in the upper layer region of the freezer 11. By operating the fan 42 of each microchannel heat exchanger 14, an air flow in the direction of arrow a ₁ across the flat tube 36 is formed. This air flow, in the internal upper region of the microchannel heat exchanger 14 is distributed installed, forced convection zone Z ₁ of the internal air is circulated in the horizontal direction is formed.

  A dehumidifying cooler chamber 50 is provided adjacent to the front chamber 20, and a dehumidifying cooler 52 is installed in the dehumidifying cooler chamber 50. An opening 53 is provided in the partition wall that partitions the dehumidifying cooler chamber 50 and the cargo handling chamber 18, and an opening 55 is provided in the partition wall that partitions the dehumidifying cooler chamber 50 and the freezer 10. These openings are provided with heat-insulating doors 54 and 56 driven by an electric motor, so that the openings can be opened and closed. When the dehumidifying cooler 52 is operated, the heat insulating door 56 is opened, the inside air is dehumidified by the dehumidifying cooler 52, and the dehumidified air is sent from the duct 58 into the freezer. When removing frost generated by dehumidification of the dehumidifying cooler 52, the heat insulating door 54 is opened and the air in the cargo compartment 18 is sent to the dehumidifying cooler 52. Drainage generated by defrosting is connected to a rain toy or the like via the drainage pipe 59 via the cargo handling chamber 18.

The anterior chamber 20 is provided with a desiccant rotor type dehumidifier 60 for a low dew point. Hereinafter, the configuration of the desiccant rotor type dehumidifier 60 will be described with reference to FIG. In FIG. 5, the air in the front chamber 20 is introduced into the dehumidifier 60 by the processing fan 64. Dust and dust are removed from the front room air by the filter 66 and precooled by the cooling coil 68. In this way, air whose relative humidity is increased is caused to flow into the adsorption zone D ₁ of the desiccant rotor 62. Desiccant rotor 62 carries a sorbent such as zeolite or silica gel, is divided into an adsorption zone D ₁ and regeneration zone D _2.

The air whose relative humidity is increased is adsorbed by the adsorbent in the adsorption zone D ₁ in the desiccant rotor 62. Since the air adsorbed with moisture is heated to high temperature by the heat of adsorption generated from the adsorbent during adsorption, the air is cooled by the cooling coil 70 to become low-temperature dry air and is supplied into the front chamber 20.

On the side of regenerating the adsorbent adsorbed by the desiccant rotor 62, the outside air oa is introduced into the dehumidifier 60 by the regeneration fan 76. After the outside air oa is removed the dust and dirt in the filter 72, is heated by the heating coil 74 is supplied with heat for desorbed water vapor partial from the regeneration zone D _2. The heated air flows into the regeneration zone D ₂ of the desiccant rotor 62, desorbed moisture adsorbed on the desiccant rotor 62 by the heat retained. The air containing the desorbed moisture is exhausted to the outside.

Returning to FIG. 4, the air in the front chamber 20 flows into the dehumidifier 60 from the inlet pipe 81, and the cooled dehumidified air adjusted by the dehumidifier 60 is returned from the outlet pipe 82 to the front chamber. Waste water generated by the dehumidifying device 60 is discharged to the outside from the drain pipe 84. The outside air oa is introduced from an air supply pipe (not shown) of the air supply / exhaust duct 86, and the exhaust after being used for regeneration of the desiccant rotor 62 is exhausted to the outside from an exhaust pipe (not shown) of the air supply / exhaust duct 86.
As shown in FIG. 6, the air supply / exhaust duct 86 is once installed in the cargo handling chamber 18, and then installed above the ceiling of the cargo handling chamber 18. The drain pipe 84 is led outside through the cargo handling chamber 18.

An opening 90 is provided in the partition wall that partitions the cargo handling chamber 18 and the front chamber 20.
An opening / closing mechanism 24 having high sealing performance is provided. The opening / closing mechanism 24 includes an air shutter device 92 that forms a double air curtain, and a sheet shutter device 94 that can open and close the entrance 90 with a sheet that moves at high speed. The opening / closing mechanism 24 allows the opening 90 to be sealed with high air density. An opening 96 is provided in a partition wall that partitions the front chamber 20 and the freezer 11, and a heat insulating door 97 that is driven by an electric motor is provided in the opening 96, thereby opening and closing the opening 96.

  A dehumidifying cooler 100 is fixed to the ceiling surface 20 a of the front chamber 20, air cooled and dehumidified is discharged from the outlet pipe 102, and condensed water is discharged from the drain pipe 104 to the outside. Further, a nolen 98 is provided to partition the entrance side of the front chamber 20 and the back side of the front chamber 20 where the exits of the outlet pipes 82 and 102 are arranged. As shown in FIG. 7, the drain pipe 104 is once led to the cargo handling chamber 18 and then led to the outside.

  The freezer 11 is provided with a low dew point desiccant rotor type dehumidifier 106 having the same configuration and function as the dehumidifier 60. The inside air is introduced into the dehumidifying device 106 from the inlet pipe 108, and the air dehumidified and cooled by the dehumidifying device 106 is supplied from the outlet pipe 110 into the inside. The outside air oa used for regeneration of the desiccant rotor is supplied to the dehumidifier 106 through the air supply / exhaust duct 112, and the exhaust after use is exhausted to the outside from the air supply / exhaust duct 112.

  In such a configuration, when the article to be frozen R is carried in and out, the openings 90 and 96 are opened, and the article R to be frozen is carried into or out of the freezer 11. During normal freezing operation, the openings 90 and 96 are closed, and the microchannel heat exchanger 14 is operating. The dehumidifying devices 60 and 106 and the dehumidifying coolers 52 and 100 need not always be operated, and are appropriately operated while managing the temperature and humidity of the internal air. After the openings 90 and 96 are opened and the outside air, which is room temperature humid air, enters the freezer 11, these devices are operated. When the dehumidifying cooler 52 is operated, the opening 53 is closed and the opening 55 is opened. During the defrost operation, the opening 53 is opened and the opening 55 is closed.

During the defrosting operation of the microchannel heat exchanger 14, the supply of the CO ₂ refrigerant to one microchannel heat exchanger 14 is stopped, the heater 49 of the microchannel heat exchanger 14 is turned on, and the flat tube 36 is warm. However, the temperature of the flat tube 36 and its vicinity is kept at 0 ° C. or lower. For example, the temperature of the internal air is kept at −25 ° C. during the freezing operation, and the flat tube 36 and its surroundings are heated by the heater 49 so as to be about −15 ° C. during the defrost operation. The defrosting operation of the microchannel heat exchanger 14 is performed by shifting the timing of the defrosting operation for each microchannel heat exchanger 14 and rotating it.

  In this embodiment, outside air oa is once introduced into the front chamber 20, and the air in the front chamber 20 is cooled and dehumidified by the low dew point desiccant rotor type dehumidifier 60 and the dehumidifier cooler 100. In this way, air that has been precooled and dehumidified in the front chamber 20 is supplied into the freezer 11. In the freezer 11, the inside air is cooled by the microchannel heat exchanger 14, and the inside air is kept at a temperature of -25 ° C. At the same time, dehumidification is performed by the desiccant rotor type dehumidifier 106 for low dew point. The dehumidifier 106 performs dehumidification so as to be equal to or less than the saturated water vapor amount with respect to the internal air temperature of −25 ° C.

For example, the front chamber 20 is maintained at a room temperature of 5 ° C. and a relative humidity of 80%. In the forced convection zone Z ₁ of the freezer 11, the air after heat exchange in the microchannel heat exchanger 14 is −27 ° C., the relative humidity is 100%, The natural convection zone Z ₂ is maintained at −25 ° C. and 100% relative humidity.

According to the present embodiment, the amount of water vapor contained in the interior air is set to be equal to or less than the amount of saturated water vapor relative to the interior air temperature, so that the water vapor partial pressure in the upper region in the interior where the microchannel heat exchanger 14 is installed is saturated. In the following, a dry atmosphere with a significantly small amount of water vapor can be obtained. By using the microchannel heat exchanger 14 in this dry atmosphere, the amount of heat exchange between the CO ₂ refrigerant and the internal air can be greatly increased, so that the operating efficiency (COP) can be dramatically improved. Moreover, compared with the conventional large-sized heat exchanger, a heat exchanger becomes compact and can reduce an installation cost.

Further, the freezer 11 held below freezing temperature, the upper layer region microchannel heat exchanger 14 is arranged to form a forced convection zone Z ₁ by the fan 42, the heat transfer surface of the microchannel heat exchanger 14 Defrosting is possible by promoting the sublimation of frozen frost by the formation of forced convection. In the defrost operation, the heater 49 is turned on, the temperature around the heat transfer surface is heated to a temperature of 0 ° C. or less, for example, about −15 ° C., and the relative humidity of the atmosphere around the heat transfer surface is reduced. Further, the sublimation of frost can be further promoted. Therefore, frost can be removed without performing a conventional defrosting operation, and a conventional defrosting device becomes unnecessary.

  Moreover, since the frost formation is not heated and dissolved by watering, a heater, or the like in the defrost process as in the prior art, energy loss in the defrost process is eliminated. Furthermore, since water as a liquid phase does not exist in the freezer 10, a refreezing prevention heater and a drain water discharge piping system are not required.

Further, the forced convection zone Z _{1 in} which the microchannel heat exchanger 14 is installed is arranged in the upper layer region in the chamber, so that the forced convection zone Z ₁ is isolated from the inlet / outlet 22, and the natural convection zone Z is formed between the inlet / outlet 22. by interposing _2, the amount of water vapor comprising a forced convection zone Z ₁ cause frost can hold relatively few dry. As a result, frost formation on the heat transfer surface of the microchannel heat exchanger 14 can be reduced. Therefore, a defrost mechanism can be eliminated and the high heat transfer function of the microchannel heat exchanger 14 can be maintained. Further, the forced convection zone Z ₁ is limited to-compartment upper zone, by the majority of the internal space and the natural convection zone Z _2, it can be reduced the power of the fan 42.

Further, natural convection zone Z ₂ close to the entrance 22 to an atmosphere containing water vapor close to the saturated water vapor amount or saturated water vapor, which in since so as to surround the object to be frozen R, can suppress drying of the frozen product R, the Quality deterioration of the frozen product R can be suppressed.
Moreover, since the defrost process of each microchannel heat exchanger 14 is performed at different timings, the internal air is not affected by the defrost operation, and the internal air temperature can always be maintained at a desired temperature.

Moreover, since the front chamber 20 was provided adjacent to the freezer 11 and the external air oa supplied into the freezer 11 in the front chamber 20 was preliminarily cooled and dehumidified, the temperature and humidity of the air in the freezer 11 Adjustment becomes easy.
Furthermore, since the desiccant rotor type dehumidifying device is adopted as the dehumidifying devices 60 and 106, the moisture in the air can be adsorbed and the adsorbed moisture can be desorbed continuously by one device. In addition, since the dehumidifying step can be performed while the refrigeration operation is continued, the operation efficiency is not lowered.

Further, the fan 42 provided individually in the vicinity of the microchannel heat exchanger 14, because it forms a forced convection zone Z ₁ in fan 42, formation of the forced convection is facilitated in a simple and low-cost means. In addition, since no hood or the like covering the microchannel heat exchanger 14 or the fan 42 is provided, it is possible to reduce the pressure loss of the air flow, thereby facilitating the formation of forced convection.

FIG. 8 compares the operating efficiencies of a conventional refrigeration facility and the refrigeration facility of the present embodiment. Conventional refrigeration equipment is one in which one or several large-capacity coolers are installed in a freezer and a fan with a large air volume is arranged. The refrigerating apparatus uses NH ₃ / CO ₂ refrigerating apparatus having the same capacity.

In FIG. 8, in the conventional refrigeration equipment, in order to maintain the internal air temperature at −25 ° C., the evaporation temperature of NH 3 is −35 ° C., the circulation temperature of the CO ₂ refrigerant is −32 ° C., the heat exchanger (cooler) It was necessary to cool the temperature of the air exiting from) to -29 ° C. On the other hand, in this embodiment, in order to maintain the internal air temperature at −25 ° C., the evaporation temperature of NH ₃ is −30 ° C., the circulation temperature of the CO ₂ refrigerant is −28 ° C., and the temperature of the air exiting the cooler is set. What is necessary is just to set it as -27 degreeC. It was found that the COP can be improved by 30% or more in the refrigeration facility of the present embodiment as compared with the conventional refrigeration facility.

In this embodiment, the dehumidifying cooler chamber 50 is provided and the dehumidifying cooler chamber 52 is installed in the dehumidifying cooler chamber 50. Instead, the dehumidifying cooler chamber 50 is eliminated and the dehumidifying cooler chamber 50 is removed. The ra 52 may be disposed adjacent to the low dew point desiccant rotor type dehumidifier 60.
Further, instead of the electric heat insulating door 56, an air shutter device 90 that forms a double air curtain may be replaced.

In addition, an air nozzle may be provided in the vicinity of the microchannel heat exchanger 14, and air may be sprayed from the air nozzle to the heat transfer surface of the microchannel heat exchanger 14 during the defrosting operation to blow off frost.
Alternatively, the heat transfer surface of the microchannel heat exchanger 14 may be made of aluminum, and the heat transfer surface may be subjected to a surface treatment that suppresses frost formation.

In the present embodiment, has been to form a forced convection zone Z ₁ in the internal upper region of the microchannel heat exchanger 14 is arranged, in the present invention, without particularly forming a forced convection zone Z ₁ However, sublimation of frost attached to the heat transfer surface of the microchannel heat exchanger 14 is possible. Further, in the present invention, the inside of the cabinet is made into a low water vapor atmosphere, so that frost formation on the heat transfer surface of the microchannel heat exchanger 14 can be sublimated and removed without particularly performing a defrost operation.

(Embodiment 2)
FIG. 9 shows an arrangement example of various devices arranged in the freezer 10. (A) shows the time of dehumidification cooling operation, (B) shows the time of defrost operation. In the figure, a front chamber 20 is disposed between the cargo compartment 18 and the freezer 10. The ceiling surface 11 a of the freezer 11 is higher than the ceiling surface 18 a of the cargo compartment 18. A microchannel heat exchanger 14 is fixed to the ceiling surface 11 a in the freezer 11, and a dehumidifying cooler 52 is fixed to the ceiling surface 11 a above the front chamber 20. A drain pipe 59 extends from the dehumidifying cooler 52 to the cargo handling chamber 18. A partition wall 120 is provided at the edge of the freezer 11 side of the ceiling surface 20a of the front chamber 20 so as to partition the region s1 where the dehumidifying cooler 52 is installed and the region 10 s2 of the freezer.

  According to this arrangement example, since the microchannel heat exchanger 14 is fixed to the ceiling surface 11a, the arrangement position of the microchannel heat exchanger 14 in the horizontal direction can be freely determined. Moreover, the installation space of the dehumidification cooler 52 can be reduced by providing the dehumidification cooler 52 in the space above the front chamber 20.

  During the dehumidifying and cooling operation, the dehumidifying cooler 52 is operated. At this time, the open space between the cargo compartment 18 and the freezer 11 is partitioned by the electric heat insulating door 54. Further, during the defrosting operation, the open space between the ceiling surface 11 a of the freezer 11 and the partition wall 120 is partitioned by the heat insulating door 56.

(Embodiment 3)
FIG. 10 shows another example of arrangement in the freezer 11. In the figure, a desiccant rotor type dehumidifier 106 for low dew point is installed on the upper surface of the ceiling of the front chamber 20. The air supply / exhaust duct 112 attached to the dehumidifier 106 is disposed on the upper surface of the ceiling of the cargo compartment 18.
Thus, by arranging the dehumidifying device 106 on the ceiling upper surface of the front chamber 20, the installation space of the dehumidifying device 106 can be saved, and by arranging the air supply / exhaust duct 112 above the ceiling of the cargo handling chamber 18, The arrangement of the air supply / exhaust duct 112 can be facilitated.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to reduce the construction cost and operating cost of refrigeration equipment, the refrigeration equipment which can eliminate the conventional defrost operation and can improve operating efficiency (COP) significantly is realizable.

10 refrigerating device 11 freezer 11a, 20a ceiling surface 12 NH ₃ / CO ₂ refrigeration system 13 CO ₂ pumps 14,200 microchannel heat exchanger 16 CO ₂ circulation pipe 16a forward 16b backward 18 material handling chamber 20 front chamber 22 entrance 24 opening and closing mechanism 30 Frame 32, 34, 202, 204 Header 36, 206 Flat tube 38, 210 Fin 40 Support frame 42 Fan (forced convection forming means)
44 Motor 46 Rotating shaft 48 Blade 49 Heater 50 Dehumidifying cooler chamber 52,100 Dehumidifying cooler 54, 56, 97 Thermal insulation door 58 Duct 59, 84, 104 Drain pipe 60,106 Desiccant rotor type dehumidifier for low dew point ( Adsorption type dehumidifier
62 Desiccant rotor 64 Processing fan 66, 72 Filter 68, 70 Cooling coil 74 Heating coil 76 Regenerating fan 81, 108 Inlet pipe 82, 102, 110 Outlet pipe 86, 112 Supply / exhaust duct 90, 96 Opening 92 Air shutter device 94 Sheet shutter Equipment 98 Nolen 102 Dehumidifying cooler 120, 218 Partition wall 210 Partition member 212 Refrigerant inlet 214 Refrigerant outlet 216 Perimeter wall R Product to be frozen Z ₁ Forced convection zone Z ₂ Natural convection zone oa Outside air r Refrigerant passage

Claims (9)

In a refrigeration method including a cooling step of cooling the air in the refrigerator with a heat exchanger provided in the freezer, and a defrosting step of removing frost adhering to the heat transfer surface of the heat exchanger,
A heat exchanger in which a plurality of minute diameter refrigerant flow paths are arranged in parallel to increase the heat transfer surface density of the flow path forming body that forms the fine refrigerant flow paths, A cooling step of cooling the internal air to a temperature of 0 ° C. or lower while forming natural convection in the vertical direction due to a temperature difference in the vertical direction between the heat exchanger and the inlet / outlet,
A dehumidification step of adsorbing the water vapor of the internal air with an adsorbent and setting the amount of water vapor contained in the internal air to a saturated water vapor amount or less with respect to the internal air temperature;
And a defrosting step of sublimating and removing frost adhering to the heat transfer surface of the heat exchanger in a low steam atmosphere formed by the dehumidifying step.   A forced convection zone that circulates the air in the cabinet between the heat exchangers in the upper layer region of the chamber is formed, and the item to be frozen is contained under the upper layer region of the chamber and containing water vapor that is close to or near the saturated water vapor amount. 2. The refrigeration method according to claim 1, wherein a natural convection zone is formed in a vertical direction due to a temperature difference in the vertical direction of the enclosure and the air in the cabinet.   The refrigeration method according to claim 1, wherein the defrosting process of each heat exchanger is performed at different timings.   The outside air is precooled and preliminarily dehumidified in the front chamber arranged adjacent to the freezer, and the outside air after the precooling and preliminary dehumidification is introduced into the freezer. The refrigeration method according to item. In a refrigeration facility in which a heat exchanger is provided inside the freezer, the refrigerant and the internal air are heat-exchanged by the heat exchanger, and the internal air is cooled.
A heat exchanger in which a large number of micro-diameter refrigerant channels are arranged in parallel to increase the heat transfer surface density of the channel-forming body that forms the micro refrigerant channel;
An adsorption dehumidifier that adsorbs the water vapor of the internal air with an adsorbent, and makes the amount of water vapor contained in the internal air less than or equal to the saturated water vapor amount with respect to the internal air temperature,
A plurality of the heat exchangers are dispersedly arranged in the upper layer area of the warehouse, and the natural air convection is formed between the heat exchanger and the inlet / outlet by the temperature difference in the vertical direction, and the air in the warehouse is kept at 0 ° C. or lower. A refrigeration facility configured to cool to a temperature and sublimate and remove frost attached to the heat transfer surface of the heat exchanger in a low water vapor atmosphere formed by the adsorption dehumidifier.   It is provided with forced convection forming means for circulating the air in the warehouse between the heat exchangers in the upper layer area of the warehouse, and surrounds the item to be frozen including water vapor saturated or near the saturated water vapor amount below the upper layer area in the warehouse, 6. The refrigeration equipment according to claim 5, wherein a natural convection zone directed in the vertical direction is formed by a temperature difference in the vertical direction of the internal air.   A front chamber is provided adjacent to the freezer, a cooler for precooling the outside air and a dehumidifier for preliminary dehumidification are provided in the front chamber, and the outside air preliminarily cooled and dehumidified in the front chamber is placed in the freezer. The refrigeration equipment according to claim 5 or 6, wherein the refrigeration equipment is introduced.   The adsorptive dehumidifier comprises a rotary rotor carrying an adsorbent on the surface, an adsorption process for adsorbing water vapor from the internal air in one area of the rotary rotor, and desorbing the water vapor adsorbed in the other area The refrigeration equipment according to claim 5, wherein the desiccant rotor type dehumidifying device performs the desorption step to be performed simultaneously and continuously.   The refrigeration equipment according to claim 6, wherein the forced convection forming means is a blower that is disposed in the vicinity of the heat exchanger and forms an air flow along a heat transfer surface of the heat exchanger.

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