JP5701572B2 - CO2 brine cooling method and cooling equipment - Google Patents

Description

  The present invention relates to a cooling method and cooling equipment that can be applied, for example, for cooling in a refrigerated warehouse or a freezer, or for cooling each room of a building.

  Patent Document 1 discloses a cooling device that cools the inside of a refrigerated warehouse that refrigerates and stores food and the like. As disclosed in Patent Document 1, conventionally, as an air cooler (air cooler), one or several unit coolers in which a fin coil and a blower are integrated are arranged in a cooling chamber. Cooling equipment of a refrigerant circulation system that circulates refrigerant through the unit cooler to cool indoor air and circulates cold air using a blower and a duct is often used.

  This type of cooling device employs a forced convection system that uses a large air volume fan to forcibly circulate the air in the cooling chamber to the lower area of the cooling chamber with high-speed cold air in order to cool the cooling chamber uniformly. Yes. However, when storing frozen food or the like in the cooling chamber, there is a problem that drying and freezing / burning occur due to high-speed cold air, and a large air volume fan is used, so that a large amount of power is required.

Patent Document 2 discloses a cooling facility using a natural refrigerant that uses NH ₃ as a primary refrigerant and circulates CO ₂ brine as a secondary refrigerant to an air cooler or the like. The configuration of this type of cooling equipment is shown in FIG. In FIG. 9, the NH ₃ / CO ₂ refrigeration apparatus 100 using NH ₃ as a primary refrigerant and CO ₂ as a secondary refrigerant is provided on the first floor of a machine room M. The NH ₃ refrigerant circuit 102 is provided with a refrigeration cycle component device including a compressor 104, a condenser 106, an expansion valve 108, and a liquefier (evaporator) 110. Liquefier 110, NH ₃ and a refrigerant and CO ₂ brine to the heat exchange, is intended to liquefy the CO ₂ brine.

A CO ₂ brine reservoir (low-pressure receiver) 112 and a liquid pump 116 are installed in the semi-basement GL of the machine room M. Air coolers 118a to 118d are provided in the rooms 01 to 04 on the first to fourth floors, respectively. A CO ₂ brine circulation path 114 connecting the liquid reservoir 112 and the liquefier 110 and a CO ₂ brine circulation path 120 connecting the liquid reservoir 112 and the air coolers 118a to 118d are provided.

A liquid pump 116 is interposed in the CO ₂ feed pipe 120a of the circulation path 120, and liquid CO ₂ brine is supplied from the liquid reservoir 112 to the air coolers 118a to 118d. A flow rate adjustment valve 122 is provided in the CO ₂ feed pipe 120a on the inlet side of each of the air coolers 118a to 118d.
With such a configuration, the low-temperature and low-pressure CO ₂ brine solution of the liquid reservoir 112 is supplied to the air coolers 118a to 118d, and the CO ₂ brine solution and the room air are heat-exchanged by the air cooler 118, and the CO ₂ brine solution The room air is cooled by evaporating a part. Then, the CO ₂ brine of the gas-liquid two-phase flow after heat exchange is returned to the liquid reservoir 112 through the CO ₂ return pipe 120b.
There is also a system in which the liquefier 110 is eliminated and the NH ₃ refrigerant circulation path 102 is directly connected to the liquid reservoir 112.

  In addition, as a compact heat exchanger having high heat exchange efficiency, a so-called “microchannel heat exchanger (multi-flow type heat exchanger)” is known. 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. In this flat tube, the peripheral wall has an oval cross section, and the internal space is partitioned by a plurality of partition walls in the direction of the long side of the cross section to form a plurality of micro-diameter refrigerant passages. A plurality of flat tubes are arranged in parallel with intervals for air flow, and fins for heat radiation are provided between the flat tubes.

  When air passes between the intervals of the flat tubes, heat is exchanged with the refrigerant. The heat transfer surface density (heat transfer area of the heat exchanger / volume of the heat exchanger) is increased by the minute diameter refrigerant flow path provided in the flat tube, thereby improving the heat exchange efficiency. Microchannel heat exchangers are widely used as vehicle radiators, car air conditioner condensers, and the like. Patent Document 4 discloses that the preferable flat tube dimensions are a tube wall thickness of 0.15 to 0.5 mm, a width of 12 to 20 mm, and a height of 1.2 to 2.0 mm. A flat tube in which five micro-diameter refrigerant channels are formed in a flat tube having a size is disclosed.

  In the brine circulation cooling facility shown in FIG. 9, in order to maintain the heat exchange amount of the air coolers 118a to 118d at a set value or more, the liquid pump 116 has a refrigerant amount (the minimum required refrigerant) that is vaporized by the air coolers 118a to 118d. 2 to 3 times the amount) is supplied to the air coolers 118a to 118d. Usually, the liquid reservoir and the liquid pump are arranged below the air cooler so that the gas-liquid two-phase refrigerant including the refrigerant vaporized by the air coolers 118a to 118d is easily returned to the liquid reservoir 112. ing.

  An example in which the liquid reservoir and the liquid pump are arranged above the air cooler is shown in FIG. In FIG. 10, an air flow a is formed inside the casing 132 of the air cooler 130 by a fan 134 provided at the outlet of the casing 132. Inside the casing 132, a refrigerant supply header 136 and a refrigerant discharge header 138 are provided. A large number of finned heat exchange tubes (not shown) are connected between the refrigerant supply header 136 and the refrigerant discharge header 138. Heat exchange is performed between the refrigerant liquid flowing in the finned heat exchange pipe and the air flow a, and the air in the cooling chamber provided with the air cooler 130 is cooled.

  Between the air cooler 130 and the liquid reservoir 140, a refrigerant circulation path 142 including a refrigerant feed pipe 142a and a refrigerant return pipe 142b is connected. A liquid pump 144 is interposed in the refrigerant feed pipe 142a.

  In this arrangement example, a liquid column caused by excess liquid refrigerant is generated in the refrigerant return pipe 142b. Therefore, when the refrigerant saturation pressure of the air cooler 130 corresponding to the room temperature maintaining the cooling chamber is P Pascal, if the liquid column pressure ΔP Pascal due to excess liquid refrigerant in the refrigerant return pipe 142b is applied, actual air cooling The saturation pressure of the gas refrigerant in the vessel 130 is (P + ΔP) Pascal. Therefore, in the air cooler 130, there is a problem that the evaporation pressure is increased by the liquid column pressure ΔP Pascal, the cooling capacity of the cooling chamber is lowered, and the cooling is poor.

In order to keep the evaporation pressure in the air cooler 130 at P Pascal, it is necessary to lower the pressure of the refrigerant return pipe 142b of the air cooler 130 and the liquid reservoir 140 to (P−ΔP) Pascal. Pressure Ekitamariki 140 to lower the (P-[Delta] P) Pascal, it is necessary to lower the evaporation temperature of the brine cooler not shown (corresponding to liquefier 110 in FIG. 9), the reason, NH ₃ refrigeration system The compressor is forced to operate at a low evaporation temperature outside the rated operation, and the efficiency decreases.

JP-A-8-226738 International Publication WO2006-38354 Republished Patent Gazette Japanese Unexamined Patent Publication No. 2-84252 JP-A-4-20791

  As described above, the conventional brine circulation cooling equipment employs a forced convection system that uses a large air volume fan and forcibly circulates the air in the cooling chamber, so that frozen foods stored in the cooling chamber, etc. However, there is a possibility that drying and freezing / burning may occur due to high-speed cold air, and a large fan power is required.

Further, the low pressure liquid receiver (liquid reservoir) and the liquid pump serve as an evaporator so that a liquid column is not formed by a refrigerant return pipe for returning the gas-liquid two-phase flow refrigerant from the air cooler to the liquid reservoir. It is necessary to arrange below the air cooler. However, since the liquid reservoir and the liquid pump are installed, the machine room on the first floor is provided with a semi-basement floor, or a machine room is provided on the basement floor. is there. This is one of the factors that hinder the switching of the refrigerant of the refrigeration apparatus to a natural refrigerant such as NH ₃ or CO ₂ .

  In view of the problems of the prior art, the present invention prevents drying and freeze-burning of articles to be cooled stored in a cooling room such as a refrigerated warehouse in a brine circulation type cooling facility, and reduces the construction cost of the cooling facility. Thus, an object is to facilitate conversion to a cooling facility using a natural refrigerant.

In order to achieve such an object, the cooling method using CO ₂ brine according to the present invention is liquefied by cooling and liquefying CO ₂ brine as a secondary refrigerant in an NH ₃ refrigeration apparatus that constitutes a refrigeration cycle using NH ₃ as a primary refrigerant. CO ₂ brine feed to the air cooler provided in the cooling chamber, the cooling method by CO ₂ brine cooling the cooling chamber,
As a heat exchanger of the air cooler, a heat exchanger in which a large number of minute diameter refrigerant flow paths are arranged in parallel and the heat transfer surface density of the flow path forming body forming the minute diameter refrigerant flow path is increased, A cooling step of cooling the cooling chamber with an air cooler unit configured by distributing a plurality of the heat exchangers in the upper layer region of the cooling chamber;
Liquefied CO ₂ brine all sent to the plurality of heat exchangers by the liquid pump is vaporized by heat exchange with the cooling room air, CO ₂ brine returning the CO ₂ brine was the vaporized liquid reservoir device of NH ₃ refrigeration system A circulation process;
The upper air region of the cooling chamber is cooled by the air cooler unit to form cooling air containing a saturated water vapor amount or a water vapor amount close to the saturated water vapor amount, and a temperature difference in the vertical direction between the upper air layer region and the lower region of the cooling chamber. And a natural convection forming process for forming natural convection in the vertical direction ,
The plurality of heat exchangers are each formed in a plate-like body, and radiate cool air obliquely downward in the direction of gravity from the heat transfer surface of the plate-like body .

In the method of the present invention , a microchannel heat exchanger having an increased heat transfer surface density is used as a heat exchanger of the air cooler, and the microchannel heat exchanger is distributed and arranged in the upper layer region of the cooling chamber. As a result, the amount of heat exchange between the CO ₂ brine and the room air can be increased, and the cooling effect can be increased. In addition, the internal volume of the flow path of the CO ₂ brine of the microchannel heat exchanger is very small. For example, in the case of a plate shape having a size of about 500 mm × 500 mm, the CO ₂ brine of about 20 cc (cm ³ ). Only possessed. Therefore, substantially all of the CO ₂ brine supplied to the microchannel heat exchanger is vaporized, so that no liquid column is formed in the refrigerant return pipe. Accordingly, the liquid reservoir and the liquid pump can be arranged above, and the arrangement position of these devices is not restricted, so that the above-described problem of the construction cost of the cooling facility can be solved.

In addition, since the plurality of microchannel heat exchangers are distributed in the upper layer region of the cooling chamber, the upper layer region of the cooling chamber can be uniformly cooled. In the conventional unit cooler, one or several units are arranged in the cooling chamber. For example, in the class F refrigerator having a scale of 1,000 tons to be refrigerated, in the method of the present invention, one conventional unit cooler is used. An air cooler composed of a dozen or more microchannel heat exchangers is distributed. Since the refrigerant holding amount of one unit cooler is 65 to 70 liters, the refrigerant holding amount of the air coolers of 10 or more microchannel heat exchangers is extremely reduced to about 0.5% of the conventional, so CO 2 The circulation flow rate of ₂ brine is also extremely small, and the power of the liquid pump can be greatly reduced.

In the method of the present invention, each of the microchannel heat exchangers and a blower that is disposed adjacent to the heat exchanger and that forms a ventilation contacting the heat transfer surface of the heat exchanger constitutes a cooler unit, Since the cooler units are dispersedly arranged in the upper layer area of the cooling chamber to cool the upper layer area of the cooling chamber and thereby increase the relative humidity, the upper layer area contains a saturated water vapor amount or a water vapor amount close to the saturated water vapor amount. Cooling air can be formed. At the same time, a temperature difference occurs in the vertical direction between the upper and lower regions of the cooling chamber , and natural convection in the vertical direction can be formed by this temperature difference. Therefore, the cooling air with high relative humidity in the upper layer area diffuses downward and can be cooled so as to wrap the article to be cooled such as frozen food stored in the cooling chamber. As a result, drying of the article to be cooled and freezing burn can be prevented.

In the method of the present invention, an air blower disposed adjacent to the microchannel heat exchanger is used to form a ventilation that is in contact with the heat transfer surface of the microchannel heat exchanger, and heat exchange between the CO ₂ brine and the room air is promoted, thereby providing an upper layer in the cooling room. A low temperature air region may be formed in the region.
In the method of the present invention, since a low-speed air flow is formed by natural convection, the suction static pressure for forming the ventilation contacting the heat transfer surface of the microchannel heat exchanger is small, and a general pressure ventilation fan is used. be able to.

In the conventional unit cooler, for example, a heat exchanger in which ten or more rows of copper tubes having a nominal diameter of about ½ are arranged is used. In this case, a suction static pressure of 10 and several mmAq is required, and in response to this, a fan of several kW is required. However, in the cooling method using the CO ₂ brine of the present invention, the conventional fan power is about 1/10. Well, it will save a lot of energy.

The cooling facility with CO ₂ brine of the present invention that can be used directly for carrying out the method of the present invention comprises:
NH ₃ and the NH ₃ refrigeration system including a refrigeration cycle component devices as the primary refrigerant, CO ₂ for circulating CO ₂ brine as a secondary coolant between said NH ₃ refrigeration system and air cooler provided in the cooling chamber In a cooling device with CO ₂ brine with a brine circuit,
The heat exchanger of the air cooler is composed of a heat exchanger in which a large number of small diameter refrigerant flow paths are arranged in parallel to increase the heat transfer surface density of the flow path forming body that forms the small refrigerant flow paths. A plurality of the heat exchangers are distributed and arranged in the upper layer region of the cooling chamber to form an air cooler unit,
A liquid pump for sending the liquefied CO ₂ in the forward of the CO ₂ brine circulation path to the air cooler unit is provided, the CO ₂ brine vaporized by heat exchange with the cooling room air in the heat exchanger to the CO ₂ brine circulation path Configure to return to the provided reservoir,
The upper air region of the cooling chamber is cooled by the air cooler unit to form cooling air containing a saturated water vapor amount or a water vapor amount close to the saturated water vapor amount, and a temperature difference in the vertical direction between the upper air layer region and the lower region of the cooling chamber. To form natural convection in the vertical direction ,
Forming ventilation in contact with the heat transfer surface of the heat exchanger with a blower arranged adjacent to the heat exchanger,
Further, the plurality of heat exchangers are formed in a plate-like body in which flat tubes each having a plurality of small-diameter refrigerant channels are arranged in parallel with a space between each other, and the heat transfer surface of the plate-like body is inclined in the direction of gravity. It arrange | positions so that it may face downward, and it was comprised so that cold air might be radiated toward diagonally downward from the heat-transfer surface of this plate-shaped object, It is characterized by the above-mentioned .

In the apparatus of the present invention, a microchannel heat exchanger having an increased heat transfer surface density is used as a heat exchanger of the air cooler, and the microchannel heat exchanger is distributed and arranged in the upper layer region of the cooling chamber. Thereby, the amount of heat exchange between the CO ₂ brine and room air can be increased, and the cooling effect can be increased. In addition, since the plurality of microchannel heat exchangers are distributed in the upper layer region of the cooling chamber, the upper layer region of the cooling chamber can be uniformly cooled.

Moreover, since the internal volume of the refrigerant flow path formed in the microchannel heat exchanger is very small and only a very small amount of refrigerant is held, substantially all of the CO ₂ brine supplied to the microchannel heat exchanger is vaporized. Is done. As a result, no liquid column is formed in the refrigerant return pipe, so that it is possible to place the liquid reservoir and the liquid pump above, and there is no restriction on the arrangement position of these devices. Can be resolved.

In addition, since the refrigerant holding amount of each air cooler is extremely reduced, the circulation flow rate of the CO ₂ brine is also small, and the power of the liquid pump can be greatly reduced. In addition, the microchannel heat exchanger is arranged in the upper layer area of the cooling chamber, and the upper layer area of the cooling chamber is cooled, thereby increasing the relative humidity. The cooling air containing can be formed. At the same time, a temperature difference occurs in the indoor air in the vertical direction, and natural convection in the vertical direction can be formed by this temperature difference. Therefore, the cooling air in the upper layer area diffuses downward and can be cooled so as to wrap the article to be cooled such as frozen food stored in the cooling chamber, so that the article to be cooled and the freezing burn can be prevented.

In the apparatus of the present invention, a microchannel heat exchanger and a blower that is arranged adjacent to the microchannel heat exchanger and forms a ventilation that contacts the heat transfer surface of the heat exchanger constitute a cooler unit, and a plurality of cooler units Are distributed in the upper layer area of the cooling chamber to cause a temperature difference in the vertical direction between the upper layer area and the lower area of the cooling chamber, so that low-speed natural convection is generated in the cooling chamber formed by natural convection in the vertical direction. to form the suction static pressure may be the only for forming ventilation in contact with the heat transfer surface of a microchannel heat exchanger, the cooling installation according to CO ₂ brine of the present invention, a conventional 1/10 blower power This is a significant energy saving.
In addition, since the cooler units having such a configuration are dispersedly arranged in the upper layer region of the cooling chamber, the upper layer region of the cooling chamber can be uniformly cooled, the temperature difference with the lower region can be easily formed, and the formation of natural convection is facilitated.

In the apparatus of the present invention, the microchannel heat exchanger is formed in a plate-like body in which flat tubes having a plurality of small-diameter refrigerant flow paths are arranged in parallel with each other, and the heat transfer surface of the plate-like body is in the direction of gravity. are arranged so as to face obliquely downward, it may be configured to radiate cold air toward the one we swash Me downward the heat transfer surface. As described above, since the cool air is radiated obliquely downward from the heat transfer surface of the microchannel heat exchanger in the gravity direction , the cooling effect of the article to be cooled stored in a refrigerated warehouse or the like can be further enhanced.

According to the method of the present invention, all the CO ₂ brine sent to the air cooler unit by the liquid pump is vaporized and no liquid column is formed in the refrigerant return pipe, so that the arrangement of the air cooler, the liquid reservoir, and the liquid pump There are no restrictions, and the construction cost of the cooling equipment can be reduced, and the power of the liquid pump that circulates the CO2 brine can be greatly reduced. In addition, natural convection can be formed in the cooling chamber, and the amount of water vapor close to the saturated water vapor amount Therefore, it is possible to prevent the article to be cooled from being dried and freeze-burned.

Further, according to the present invention apparatus, air-gas cooling chamber upper region by a cooler unit to cool, thereby forming a cooling air containing nearly water vapor to the saturated water vapor content or saturated water vapor, vertical in the cooling air Since the temperature difference is generated and the natural convection in the vertical direction is formed, the same effect as the method of the present invention can be obtained.

1 is an overall perspective view of a refrigeration facility according to an embodiment of the method and apparatus of the present invention. It is a perspective view which shows the structural example of the air cooler used for the said refrigeration equipment. It is sectional drawing which follows the AA line in FIG. It is a front view of the microchannel heat exchanger used for the said refrigeration equipment. It is a side view of the microchannel heat exchanger. It is sectional drawing which follows the BB line in FIG. It is a perspective view which shows another structural example of an air cooler. It is a perspective view which shows another structural example of an air cooler. It is a block diagram which shows an example of the conventional brine circulation type refrigeration apparatus. It is a block diagram which shows a part of brine circulation type freezing apparatus at the time of arrange | positioning a liquid reservoir and a liquid pump upwards.

  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.

An embodiment in which the method and apparatus of the present invention are applied to a refrigeration facility equipped with a refrigerated warehouse will be described with reference to FIGS. In the refrigeration facility 10 of the present embodiment shown in FIG. 1, an NH ₃ / CO ₂ refrigeration apparatus 14 is provided outside the refrigerated warehouse 12. The NH ₃ / CO ₂ refrigeration apparatus 14 includes NH ₃ as a primary refrigerant and equipment (not shown) that constitutes the refrigeration cycle of the NH ₃ refrigerant. This refrigeration cycle component device is provided with a liquefier, and a liquid reservoir is connected to the liquefier via a CO ₂ brine circulation pipe. That is, these component devices are the same as the component devices provided in the machine room M of FIG.

A CO ₂ circulation path 16 is connected to the liquid reservoir (not shown). A liquid pump 18 is provided in the CO ₂ liquid feed pipe 16 a of the CO ₂ circulation path 16. The CO ₂ brine is sent to the air cooler 20 disposed in the refrigerated warehouse 12 by the liquid pump 18. A number of air coolers 20 are arranged in the upper layer area u in the refrigerated warehouse 12. In the refrigerated warehouse 12, an entrance / exit 24 for carrying in or out the article R to be cooled is provided facing the cargo handling room 22, and an opening / closing mechanism 26 having good sealing performance is provided at the entrance / exit 24. Hereinafter, the configuration of the air cooler 20 will be described.

  2 and 3 show a configuration example of the air cooler 20. In the figure, a casing 202 of the air cooler 20 is provided with a front opening 204 and a bottom opening 206 in order to form a flow of room air as indicated by an arrow. The front wall 208, the top wall 210, the back wall 212, the right side wall 214, the left side wall 216, and the bottom wall 218 other than these openings are configured as shielding walls. The arrangement position and fixing means of the air cooler 20 may be arranged such that the back wall 212 is in contact with the inner wall surface of the upper layer area of the refrigerated warehouse 12 and the back wall 212 is fixed to the inner wall surface. The back wall 212 and the left and right side walls 214 or 216 may be fixed to the inner wall of the refrigerated warehouse 12 at the four corners of the warehouse 12. Alternatively, a hanging tool may be attached to the top wall 210 so that the air cooler 20 is suspended from the ceiling of the refrigerated warehouse 12.

  A fan 220 is attached to the front wall 208. The fan 220 and the drive motor 222 of the fan 220 are supported by the support frame 224. Inside the casing 202, the microchannel heat exchanger 30 configured in a plate shape is disposed in the diagonal direction of the left and right side walls 214, 216. A triangular partition wall 226 that partitions the inside of the casing 22 on the front side of the microchannel heat exchanger 30 is provided in the center of the casing 202. Hereinafter, the configuration of the microchannel heat exchanger 30 will be described with reference to FIGS.

  4 to 6, the microchannel heat exchanger 30 includes a plurality of headers 302 and 304 arranged in parallel with each other and a plurality of headers 302 and 304 which are laid between the headers 302 and 304, and the inside communicates with the headers 302 and 304. A flat tube 306 and a heat dissipating fin 308 provided between the flat tubes 306 are configured.

  As shown in FIG. 6, the flat tube 306 has a large number of minute-diameter refrigerant channels 314 drilled therein. The minute diameter refrigerant flow path 314 is provided in parallel in the axial direction of the flat tube 306. Between each flat tube 306, the space | interval I for letting room air pass is provided, and the fin 308 for thermal radiation bent by the meandering shape at this space | interval I is provided. Thus, the microchannel heat exchanger 30 has a high heat transfer surface density and a high heat exchange capability.

In this configuration, the secondary refrigerant CO ₂ is supplied from the NH ₃ / CO ₂ refrigerating apparatus 14 to the air cooler 20 by the liquid pump 18 through the CO ₂ feed pipe 16 a in the liquid phase state. Each air cooler 20 is connected in parallel to the CO ₂ feed pipe 16a. By operating the fan 216, the air cooler 20 forms a flow of room air in the direction of the arrow. That is, it flows from the front opening 204 and the bottom opening 206 and passes through the interval I of the microchannel heat exchanger 30. The airflow then bends toward the fan 216 and exits from the fan 216 to the outside of the casing 202.

On the other hand, in each air cooler 20, liquid phase CO ₂ brine r flows from the inlet pipe 310 of the microchannel heat exchanger 30, and then flows through the minute diameter refrigerant flow path 314 of the flat tube 306 via the header 304. At this time, the CO ₂ brine solution and the room air exchange heat. Since the volume of each minute diameter refrigerant flow path 314 is extremely small and the microchannel heat exchanger 30 has a high heat transfer surface density, heat exchange with high heat exchange efficiency is performed. For this reason, the entire amount of CO ₂ brine r when it reaches the outlet pipe 312 via the header 302 is vaporized.

The vaporized CO ₂ brine r returns to the CO ₂ return pipe 16b. The CO ₂ brine returns to the liquid reservoir (not shown) from the CO ₂ brine return pipe 16b while being vaporized, and is further cooled and liquefied by the NH ₃ refrigerant in the liquefier of the NH ₃ / CO ₂ refrigeration apparatus 14. The liquefied CO ₂ brine is stored in the liquid reservoir and sent again to the air cooler 20 via the CO ₂ feed pipe 16a.

According to the present embodiment, the microchannel heat exchanger 30 with increased heat transfer surface density is used as the heat exchanger of the air cooler 20, and the microchannel heat exchanger 30 is dispersedly arranged in the upper layer region u of the cooling chamber. Therefore, the amount of heat exchange between the CO ₂ brine and the room air can be increased, and the cooling effect can be increased. Further, the inner volume of the small-diameter refrigerant channel 314 formed by extrusion on the flat tube 306 is very small. For example, in the case of a plate having a size of about 500 mm × 500 mm, 20 cc (cm ³ ) Only about ₂ CO ₂ brine is retained.

Therefore, substantially the entire amount of the CO ₂ brine supplied to the microchannel heat exchanger 30 is vaporized, so that no liquid column of liquid CO ₂ brine is formed in the CO ₂ return pipe 16b. Therefore, the liquid reservoir and the liquid pump can be arranged above, and the arrangement position of these devices is not restricted. As a result, the cooling capacity of the air cooler 20 is not reduced, and it is not necessary to provide a liquid reservoir, a liquid pump, or the like on the semi-basement floor or basement floor, thereby reducing the construction cost of the NH ₃ / CO ₂ refrigeration apparatus 14. You can save.

In addition, since the air coolers 20 are distributed in the upper layer area u in the refrigerated warehouse, the upper layer area u can be uniformly cooled. In a class F refrigerator having a scale of 1,000 tons to be refrigerated, the air coolers 20 of ten or more microchannel heat exchangers are distributed in this embodiment with respect to one conventional unit cooler. Since the refrigerant holding amount of one conventional unit cooler is 65 to 70 liters, the refrigerant holding amount of 10 or more microchannel heat exchangers is extremely reduced to about 0.5% of the conventional unit, The circulation flow rate of the CO ₂ brine is also small, and the power of the liquid pump 18 can be greatly reduced.

In addition, since the air cooler 20 is disposed in the upper layer area u in the refrigerated warehouse 12 and the upper layer area u is cooled, cooling air containing a saturated water vapor amount or a water vapor amount close to the saturated water vapor amount in the upper layer area u. Can be formed. At the same time, a temperature difference occurs in the indoor air in the vertical direction, and the natural convection a ₁ in the vertical direction can be formed by this temperature difference. Therefore, the cooled high relative humidity cooling air in the upper layer area u diffuses downward, and can be cooled by wrapping the article R to be cooled such as frozen food stored on the floor surface of the refrigerated warehouse 12. Thereby, drying and freezing burn of the article R to be cooled can be prevented.

  Further, in the present embodiment, since it is not necessary to form forced convection, the suction static pressure for forming the ventilation in contact with the heat transfer surface of the microchannel heat exchanger 30 may be small, and the fan 216 for forming the ventilation is used. A general pressure ventilation fan can be used. In a conventional 1,000-ton F class refrigerator unit cooler, for example, a heat exchanger in which a dozen rows of copper tubes having a nominal diameter of about ½ are used is used. Pressure is required, and two 2.2 kw fans are required, but in this embodiment, a fan with a power of about 50 w can be used as the fan 216, so even if 10 air coolers 20 are installed, The fan power can be reduced to about 1/10 compared with the conventional one, which greatly saves energy.

Further, since the air coolers 20 are distributed and arranged in the upper layer area u in the refrigerated warehouse 12, the upper layer area u in the refrigerated warehouse can be uniformly cooled. This allows for easy temperature difference formation with the lower zone facilitates formation of natural convection a _1.

  Furthermore, since the microchannel heat exchanger 30 is formed in a plate-like body, and this plate-like body is directed obliquely downward, the cold air is radiated obliquely downward from the heat transfer surface of the plate-like body. Can do. Since this radiant cold can be directly applied to the article to be cooled stored on the floor surface of the refrigerator warehouse 12, the cooling effect of the article to be cooled R can be further enhanced.

  FIG. 7 shows another configuration example of the air cooler 20. In FIG. 7, this air cooler 20 </ b> A has two fans 220 and two microchannel heat exchangers 30 arranged symmetrically with respect to the center of the casing 202. The configuration of the fan 220 and the microchannel heat exchanger 30 is the same as that of the above embodiment.

  In the air cooler 20 </ b> A, two microchannel heat exchangers 30 are arranged side by side in the casing 202, and are arranged obliquely downward like the air cooler 20. The casing 202 has a wall other than the front opening 204 and the bottom opening 206 formed of a closed wall. Each microchannel heat exchanger 30 and between the microchannel heat exchanger 30 and the fan 220 are partitioned by a triangular partition wall 226. The room air flows from the front opening 204 and the bottom opening 206, bends toward the fan 220 in the casing 202, and exits the fan 220.

  The air cooler 20A is used as one cooling unit, and a large number of air coolers 20A are distributed in the upper layer u of the cooling chamber such as the refrigerated warehouse 12. Since the air cooler 20A has a cooling capacity approximately twice that of the air cooler 20 of the above-described embodiment, the number of installed air coolers can be halved from the air cooler 20 for a cooling chamber that requires the same cooling capacity. Therefore, according to the air cooler 20A, in addition to the operational effects of the air cooler 20, there is an advantage that it is possible to save installation work.

  FIG. 8 shows still another configuration example of the air cooler 20. In FIG. 8, the air cooler 20B is obtained by further adding one microchannel heat exchanger 30 as compared with the air cooler 20A. Other configurations are the same as those of the air cooler 20A. Since the air cooler 20B can increase the cooling capacity by increasing the number of microchannel heat exchangers 300 compared to the air cooler 20A, the number of installed air coolers 20B can be further reduced compared to the air cooler 20A, and installation work can be reduced. You can save.

  As a configuration example of the microchannel heat exchanger 30, for example, the plate thickness is 20 mm, and the microchannel heat exchanger 30 is configured in a 500 mm square plate-like body. The dimensions of the flat tube 306 at this time are a tube thickness of 2 mm, a tube width of 20 mm, and a tube length of about 500 mm, and 16 micro-diameter refrigerant channels 314 having a channel diameter of 0.86 mm are drilled in parallel in the flat tube. The flat tubes 306 have a pitch of about 10 mm and 55 are arranged in parallel. The refrigerant capacity of one unit cooler in a conventional 1,000-ton class F refrigerator is 65 to 70 liters, whereas the total volume per microchannel heat exchanger of this small diameter refrigerant flow path 314 is Is about 20 cc, and a dozen micro-channel heat exchangers correspond to one conventional unit cooler, so that it is drastically reduced to 0.5% compared to the conventional unit cooler.

Therefore, the entire amount of liquid phase CO ₂ brine can be vaporized and the power of the liquid pump 18 can be greatly reduced. For the inlet pipe 310 and the outlet pipe 312, for example, a nominal diameter 3/8 copper pipe is used.

Two 2.2 kW fans are mounted on one unit cooler of a conventional 1,000-ton class F class refrigerator. On the other hand, in the present invention, since a fan with a power of about 50 w can be used, even if ten air coolers 20 are installed, the fan power can be reduced to about 1/10 compared with the conventional one.
In addition, although the said embodiment applies this invention to refrigeration equipment, this invention is applicable also to the freezing equipment which freezes and preserves fresh food etc., the refrigeration of each room of a building, etc.

  According to the present invention, it is suitable for use in cooling a refrigerated warehouse, a freezer, and each room of a building, preventing drying and freezing / burning of articles to be cooled in the cooling room, and reducing the construction cost of cooling equipment, The conversion of cooling equipment to natural refrigerant can be promoted.

10 refrigerating equipment 12 cold stores 14,100 NH ₃ / CO ₂ refrigeration system 16 CO ₂ circulation path 16a CO ₂ feed pipe 16b CO ₂ return pipe 18,116,144 pump 20,20A, 20B, 118a~d, 130 air Cooler 202 Casing 204 Front opening 206 Bottom opening 208 Front wall 210 Top wall 212 Back wall 214 Right side wall 216 Left side wall 218 Bottom wall 220 Fan (blower)
222 Drive motor 224 Support frame 226 Bulkhead 22 Loading room 24 Entrance / exit 26 Opening / closing mechanism 30 Microchannel heat exchanger 302, 304 Header 306 Flat tube 308 Fin 310 Inlet pipe 312 Outlet pipe 314 Small diameter refrigerant flow path 102 NH ₃ refrigerant circulation path 104 Compressor 106 Condenser 108 Expansion valve 110 Liquefier 112,140 Reservoir 114 CO ₂ brine circulation path 122 Flow rate adjustment valve 132 Casing 134 Fan 136 Refrigerant supply header 138 Refrigerant discharge header 142 Refrigerant circulation path 142a Refrigerant feed pipe 142b Refrigerant return Pipe R Cooled parts a ₀ Air flow a ₁ Natural convection r CO ₂ brine

Claims (4)

The NH ₃ is cooled liquefying CO ₂ brine are secondary refrigerant NH ₃ refrigeration apparatus constituting the refrigerating cycle as a primary refrigerant, sends the liquefied CO ₂ brine to an air cooler provided in the cooling chamber, the cooling In the cooling method with CO ₂ brine for cooling the room,
As a heat exchanger of the air cooler, a heat exchanger in which a large number of minute diameter refrigerant flow paths are arranged in parallel and the heat transfer surface density of the flow path forming body forming the minute diameter refrigerant flow path is increased, A cooling step of cooling the cooling chamber with an air cooler unit configured by distributing a plurality of the heat exchangers in the upper layer region of the cooling chamber;
Liquefied CO ₂ brine all sent to the plurality of heat exchangers by the liquid pump is vaporized by heat exchange with the cooling room air, CO ₂ brine returning the CO ₂ brine was the vaporized liquid reservoir device of NH ₃ refrigeration system A circulation process;
The upper air region of the cooling chamber is cooled by the air cooler unit to form cooling air containing a saturated water vapor amount or a water vapor amount close to the saturated water vapor amount, and a temperature difference in the vertical direction between the upper air layer region and the lower region of the cooling chamber. And a natural convection forming process for forming natural convection in the vertical direction ,
A cooling method using CO ₂ brine, wherein the plurality of heat exchangers are each formed in a plate-like body, and cool air is radiated obliquely downward in the direction of gravity from the heat transfer surface of the plate-like body . Each of the heat exchangers and a blower that is disposed adjacent to the heat exchanger and forms a ventilation that contacts the heat transfer surface of the heat exchanger constitute a cooler unit, and the cooler unit is placed in the upper layer area of the cooling chamber. _{2. The} cooling method using CO ₂ brine according to claim 1 , wherein a temperature difference in the vertical direction is generated between the upper layer region and the lower region of the cooling chamber in a distributed manner. NH ₃ and the NH ₃ refrigeration system including a refrigeration cycle component devices as the primary refrigerant, CO ₂ for circulating CO ₂ brine as a secondary coolant between said NH ₃ refrigeration system and air cooler provided in the cooling chamber In a cooling device with CO ₂ brine with a brine circuit,
The heat exchanger of the air cooler is composed of a heat exchanger in which a large number of small diameter refrigerant flow paths are arranged in parallel to increase the heat transfer surface density of the flow path forming body that forms the small refrigerant flow paths. A plurality of the heat exchangers are distributed and arranged in the upper layer region of the cooling chamber to form an air cooler unit,
A liquid pump for sending the liquefied CO ₂ in the forward of the CO ₂ brine circulation path to the air cooler unit is provided, the CO ₂ brine vaporized by heat exchange with the cooling room air in the heat exchanger to the CO ₂ brine circulation path Configure to return to the provided reservoir,
The upper air region of the cooling chamber is cooled by the air cooler unit to form cooling air containing a saturated water vapor amount or a water vapor amount close to the saturated water vapor amount, and a temperature difference in the vertical direction between the upper air layer region and the lower region of the cooling chamber. To form natural convection in the vertical direction ,
Forming ventilation in contact with the heat transfer surface of the heat exchanger with a blower arranged adjacent to the heat exchanger,
Further, the plurality of heat exchangers are formed in a plate-like body in which flat tubes each having a plurality of small-diameter refrigerant channels are arranged in parallel with a space between each other, and the heat transfer surface of the plate-like body is inclined in the direction of gravity. A cooling facility using CO ₂ brine , which is arranged so as to face downward and radiates cold air obliquely downward from the heat transfer surface of the plate-like body . A heat exchanger of said respective arranged adjacent to the heat exchanger to form a ventilation in contact with the heat transfer surface of the heat exchanger constitutes the condenser unit by the fan, the cooling chamber a plurality of cold却器unit The cooling facility using CO ₂ brine according to claim 3 , wherein the temperature difference in the vertical direction is generated between the upper layer region and the lower region of the cooling chamber by being distributed in the upper layer region.

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