Sublimation defrost system for refrigeration devices and sublimation defrost method.

SUBLIMATION DEFROSTING SYSTEM

FOR REFRIGERATION DEVICES AND DEFROSTING METHOD BY SUBLIMATION

TECHNICAL FIELD

The present description refers to a sublimation defrost system and sublimation defrost method in which the frosts attached to a heat exchange pipe arranged in a cooling device is eliminated through sublimation without melting the frost, the system and method applied to a refrigeration apparatus in which a CO2 refrigerant can circulate in the cooling device arranged in a freezer to cool the inside of the freezer.

BACKGROUND

To avoid depletion of the ozone layer, global heating and natural refrigerants, such as NH3 or CO2 have been checked as refrigerant in a refrigeration device used for room air conditioning and refrigeration of food products. Therefore, refrigeration appliances that use NH3, with high cooling performance and toxicity, as primary refrigerant and CO2 use, without toxicity or odor, since they have been widely used as a secondary refrigerant.

In the refrigeration apparatus, a primary refrigerant circuit and a secondary refrigerant circuit are connected to each other through a cascade condenser. The heat exchange between the NH3 refrigerant and the CO2 refrigerant takes place in the cascade condenser. The CO2 refrigerant cooled and liquefied with the NH3 refrigerant is sent to a cooling device arranged in the freezer, and cools the air in the freezer through a heat transfer pipe arranged in the cooling device. The CO2 refrigerant partially vaporized in it is

<td>go back to</td><td>condenser</td><td>in</td><td>waterfall across</td><td>of the</td><td>circuit</td>

<td>refrigerant</td><td>secondary,</td><td>what</td><td colspan="2">cools and liquefies from</td><td>new in</td>

<td colspan="2">the cascade condenser The frost is</td><td>joins</td><td>to a pipe of</td><td colspan="2">exchange of</td>

heat disposed in the refrigeration device while the refrigeration apparatus is in operation, and therefore the heat transmission efficiency is degraded. Therefore, the operation of the refrigeration apparatus needs to be stopped periodically, to carry out defrosting.

Conventional defrosting methods for the heat exchange pipe disposed in the cooling device include a method of spraying water on the heat exchange pipe, a method of heating the heat exchange pipe with an electric heater, and the like. . Defrosting by spraying water ends up producing a new source of ice, and heating by the electric heater is against the attempt to save energy because valuable energy is wasted. In particular, water spray defrosting requires a large capacity tank and water supply and discharge pipes with a large diameter, and therefore increases the cost of plant construction.

Patent Documents 1 and 2 describe a defrosting system for the refrigeration apparatus described above. A defrosting system described in Patent Document 1 is provided with a heat exchanger part unit that evaporates the CO2 refrigerant with the heat produced in the NH3 refrigerant, and achieves defrosting allowing the hot CO2 gas generated in the heat exchanger part unit circulate in the heat exchange pipe in the cooling device.

A defrosting system described in Patent Document 2 is provided with a heat exchanger part unit that heats the CO2 refrigerant with water that has absorbed heat from the exhaust of the NH3 cooling refrigerant, and achieves defrosting allowing the Hot CO2 refrigerant circulates in the heat exchange pipe in the cooling device.

Patent Document 3 describes a method for providing a heating pipe in the cooling device separately and independently from a cooling pipe, and the frost attached to the cooling pipe is melted and removed allowing the hot water or hot brine flow into the heating pipe at the time of a defrosting operation.

An ideal defrosting method involves defrosting by sublimation. In this method, a surface of the heat exchange pipe is heated uniformly to a temperature not exceeding 0 ° C, that is, without converting the frost to water, so that the frost is removed from the surface of the heat pipe. heat exchange by sublimation. This method does not involve any drainage, and therefore does not require installation of drainage or unloading tray, and therefore can greatly reduce an installation cost. The applicants have proposed a first method of cooling the freezer's indoor air to a temperature at or below 0 ° C, and the removal of frost attached to the heat exchanger tube of the cooling device, in a low steam atmosphere reached by dehumidification, by an adsorption dehumidifying device through sublimation (Patent Document 4).

Appointment List

Patent Literature

Patent Document 1: Patent Application

Japanese Open to the Public No. 2010-181093

Patent Document 2: Patent Application

Japanese Open to the Public No. 2013-124812

Patent Document 3: Patent Application

Japanese Open to the Public No. 2003-329334

Patent Document 3: Patent Application

Japanese Open to the Public No. 2012-072981

SUMMARY

Technical Problem

Each of the defrosting systems described in patent documents 1 and 2 require the pipes for the CO refrigerant? and the NH refrigerant₃in a different system of the cooling system to be built at the installation site, and therefore can increase the cost of plant construction. The heat exchanger part unit is installed separately outside the freezer, and therefore additional space is required for the installation of the heat exchanger part unit.

In the defrosting system in Patent Document 2, a pressurization / depressurization unit is necessary to avoid thermal shock (sudden heating / heat) in the heat exchange pipe. To prevent freezing of the heat exchanger part unit, where the freezing water and the coolant exchange heat of CO2, it is necessary to carry out a discharge operation of the coolant water in the exchanger part unit of heat after finishing the defrosting operation. Therefore, there is a problem in which, for example, an operation is complicated.

<td>The</td><td>unit of</td><td>defrosting</td><td>described in the</td>

<td>Document from</td><td colspan="2">Patent 3 has a problem in</td><td>that efficiency</td>

<td>of the transmission</td><td>heat sion</td><td>is low due to</td><td>that the pipe of</td>

<td>refrigeration plaque and simile</td><td>heats up ares.</td><td colspan="2">from the outside with fins of</td>

<td>By</td><td>other part,</td><td>on a device</td><td>of refrigeration</td>

<td>cascading:</td><td>a circuit</td><td>of refrigerant</td><td>primary in the</td>

NH3 refrigerant circulates and is provided in a refrigeration cycle component; and a secondary refrigerant circuit in which the CO2 refrigerant circulates and the refrigeration cycle component is arranged, the secondary refrigerant circuit is connected to the primary refrigerant circuit through a cascade condenser, the secondary refrigerant circuit contains CO2 gas With high temperature and high pressure. Therefore, defrosting can be achieved by allowing the hot CO2 gas to circulate in the heat exchange pipe in the cooling device. However, the cascade cooling device has the following problems. Specifically, the device is complicated and involves high costs because selector valves, bypass tubes, and the like are provided. On the other hand, a control system is unstable due to the high / low temperature heat balance.

In the sublimation defrost described above, the frost on the surface of the heat exchange pipe has to be heated uniformly to a temperature not exceeding Q ° C. However, it is difficult to heat the heat exchange pipe evenly at a temperature not exceeding 0 ° C with a general heating method employed in the defrosting method described in Patent Document 4. Therefore, sublimation defrosting has not been implemented.

The present invention is made in view of the problem described above, and an object of the present invention is to achieve the reduction of the initial and operating costs necessary for a refrigeration and energy saving apparatus, by implementing the sublimation defrosting method. described above.

Solution to the problem

A defrost system according to at least one embodiment of the present invention:

(1) A sublimation defrost system for a refrigeration apparatus that includes: a refrigeration device that is arranged in a freezer, and includes a housing and a heat exchange pipe arranged in the housing; a cooling device for cooling and liquefying a CO2 refrigerant; and a refrigerant circuit that is connected to the heat exchange pipe and that is configured to allow the cooled and liquefied CO2 refrigerant in the cooling device to circulate the heat exchange pipe, the defrosting system including :

a dehumidifying device for dehumidifying the freezer's indoor air in the freezer;

a CO2 circulation path that is formed of a path of the path formation connected to an input path and an output path of the heat exchange pipe, and includes the heat exchange pipe;

an on-off valve disposed on each of the inlet path and the outlet path of the heat exchange pipe and configured to be closed at a time of defrosting so that the CO2 circulation path becomes a closed circuit;

a circulation unit for CO2 refrigerant, the unit that circulates being arranged in the CO2 circulation path;

a first heat exchanger part configured to cause heat exchange between a brine as a first heating medium and the CO refrigerant₂ circulating in the CO2 circulation path; and a pressure adjustment unit that adjusts a CO refrigerant pressure₂ circulating in the closed circuit at the time of defrosting so that a condensing temperature of the CO2 refrigerant is made equal to or less than a freezing point of a water vapor in the inner air of freezer in the freezer, in the which can be achieved defrosting without a drain receiving unit.

In configuration (1), when defrosting is performed, when the freezer inside air in the freezer has saturated water vapor pressure, the freezer inside air is first dehumidified by the dehumidifying device, so that the pressure is reduced partial water vapor. Then, the shut-off valve is closed so that the CO2 circulation path becomes the closed circuit.

Then, the pressure adjustment unit adjusts the CO refrigerant pressure₂ circulating in the closed circuit so that the condensation temperature of the CO refrigerant₂ it becomes equal to or less than a point of water vapor in the freezer's indoor air in the freezer freezer. Then, the CO2 refrigerant is allowed to circulate in the closed circuit through the circulation unit.

For example, the circulation unit is a liquid pump arranged in the CO2 circulation path to allow a C0 refrigerant₂ liquid to circulate in the closed circuit, and the like. For example, the pressure adjustment unit includes a pressure sensor that detects the refrigerant pressure of C0₂ or a unit that detects the temperature of the CO refrigerant₂ and get the coolant pressure of C0₂ based on the saturated pressure of the CO refrigerant₂ corresponding to the temperature detection value.

Next, a hot brine as a heating medium heats up the CO refrigerant₂ circulating in the closed circuit in the first part of the heat exchanger, whereby the CO refrigerant evaporates₂. Then the CO refrigerant₂ Vaporized is circulated in the closed circuit. Therefore, the frost attached to the outer surface of the heat exchange pipe is eliminated through the sublimation by heat of the CO refrigerant gas₂. CO refrigerant₂ which has imparted heat to the frost is liquefied, and then heated and evaporated again in the first part of the heat exchanger. The freezer includes a refrigerator and everything that forms other cooling spaces. The inlet path and the outlet path of the heat exchange pipe are areas of the heat exchange pipe disposed in the freezer. The areas extend from a range around a partition wall of the cooling device housing on the outer side of the housing.

The conditions required for sublimation of the frost attached to the outer surface of the heat exchange pipe are: (1) the partial water vapor pressure of the freezer's indoor air is not as high as the saturated water vapor pressure , and (2) the frost temperature is equal to or less than the freezing point. As a condition it is preferable but not necessary, (3) that the sublimated steam is dissipated by the formation of air flow on the outer surface of the heat exchanger part. Frost can be sublimated by heating the frost under these conditions.

In the configuration (1), the frost attached to the outer surface of the heat exchange pipe is heated with the heat of the CO2 refrigerant flowing in the heat exchange pipe. Therefore, the entire area of ​​the heat exchange pipe can be heated evenly. The pressure in the closed circuit is adjusted, so that the condensation temperature of the CO2 refrigerant is controlled. Therefore, the temperature of the CO2 refrigerant gas flowing in can be precisely controlled. Therefore, the frost can be accurately heated to a temperature at or below the freezing point, whereby sublimation defrosting can be achieved.

The frost attached to the heat exchange pipe does not melt but is sublimated, and therefore a drain pan and an installation for the discharge of the accumulated drain in the drain pan is not required, so the cost of the appliance Refrigeration can be greatly reduced. The frost attached to the heat exchange pipe is heated from the inside through a wall of the pipe of only the heat exchange pipe. Therefore, heat exchange efficiency can be improved and energy saving can be achieved.

Defrosting can be achieved with the CO refrigerant₂ in a low pressure state corresponding to the condensation temperature equal to or less than the point of water vapor in the freezer freezer. Therefore, a piping system device such as the CO circulation path₂ It does not need to be pressure resistant, so a high cost is not required.

In some embodiments, in configuration (1), (2) 1 a path of path formation circulation is a branched defrosting circuit from the inlet path and the outlet path of the heat exchange pipe, and the part Heat exchanger is formed in the defrosting circuit.

In configuration (2), the defrosting circuit is provided, whereby a portion where the first part of the heat exchanger is installed can be determined more freely.

In some embodiments, in configuration (1), (3) the path of the path formation is a bypass path disposed between the inlet path and the outlet path of the heat exchange pipe, and the first part of the heat exchanger is

<td>shape</td><td>in an area</td><td>partial of</td><td>the</td><td>pipeline</td><td>from</td><td>exchange</td><td>from</td>

<td>hot.</td><td>In that of</td><td colspan="2">setting</td><td> (3) ,</td><td>the</td><td>trajectory</td><td>from</td>

<td colspan="2">CO2 circulation</td><td>it is formed of</td><td>the</td><td>pipeline</td><td>from</td><td>exchange</td><td>from</td>

heat, except for the bypass path. Therefore, there is no need to additionally provide new tubes to form the CO2 circulation path, with the exception of the bypass path, so a high cost is not required.

In some embodiments, in any of the configurations (1) to (3), (4) the CO2 circulation path is formed with a difference in elevation, and the part of the first heat exchanger is formed in a lower zone of The CO2 circulation path, and the circulation unit is configured to allow the CO2 refrigerant to circulate naturally in the closed circuit at the time of defrosting by a thermosiphon effect.

In the configuration (4), the CO2 refrigerant in the lower zone of the heat exchange pipe is heated by the brine as a heating medium that evaporates in the first part of the heat exchanger. The vaporized CO2 refrigerant is allowed to increase in the closed circuit due to the thermosiphon effect. The CO2 refrigerant that arises in the upper zone of the closed circuit heats and eliminates the frost attached to the outer surface of the heat exchange pipe through sublimation and then liquefies. C0 refrigerant₂ smoothie descends by gravity.

In configuration (4), the C0 refrigerant₂ it can be allowed to circulate naturally in the closed circuit by the effect of thermosiphon. Therefore, a unit for the force that circulates the CO refrigerant is not required₂ in the closed circuit, and no equipment and power are required to force circulation, thereby reducing costs.

In some modalities, any of the configurations (1) to (4) also includes:

(5) a second part of the heat exchanger for heating the brine with a second heating means; and a brine circuit to allow brine heated by the second heating unit that was distributed to the first heating unit, the brine circuit is connected to the first heating unit and the second heating unit. Any heating medium other than cooling water can be used as the second heating medium. Said heating means includes, for example, high temperature and high pressure refrigerant gas discharged from which the cooling device forms, hot discharge water from a compressor factory, a medium that has absorbed heat emitted from a heat boiler or potential of an oil cooler, and the like. In the configuration (5), the second part of the heat exchanger and the brine circuit are provided, whereby the heated brine can be supplied to the first part of the heat exchanger, and the brine circuit can be disposed of accordingly with a position disposed of the first heat exchanger part. Therefore, a position in which the heat exchanger part is arranged can be determined more freely.

In some embodiments, in configuration (5), (6) the heat exchange pipe is provided with a difference in elevation in the cooling device, the brine circuit is formed in the cooling device and in a lower zone of the heat exchange pipe, and the first part of the heat exchanger is formed between the brine circuit and the lower zone of the heat exchange pipe.

In the configuration (6), the frost attached to the outer surface of the heat exchange pipe can be eliminated through sublimation with the CO refrigerant₂ Vaporized in the lower area of ​​the heat exchange pipe can circulate naturally by the effect of thermosiphon. Therefore, no additional pipes other than the heat exchange pipe are required, and no equipment is required to force the circulation of the CO2 refrigerant. All things considered, the cost of the cooling device can be reduced.

The brine bypass circuit is not arranged in the upper area of ​​the heat exchange pipe, so that the energy used for the fan for the formation of air flow in the cooling device can be reduced. The cooling performance of the cooling device can be improved by also providing the heat exchange pipe in an empty space in the upper area.

In some embodiments, in configuration (5), (7) each of the heat exchange pipe is provided and the brine circuit is provided with a difference in elevation in the cooling device and is configured such that the brine flows from a lower side of an upper side in the brine circuit, and a flow adjustment valve is disposed in an intermediate position in the brine circuit in an upper and lower direction, and the first part of the heat exchanger is formed in a portion of the brine circuit on a side upstream of the valve

<td rowspan="2">adjustment of</td><td colspan="5">flow.</td>

<td>In</td><td>the configuration (7), the</td><td>flow of</td><td>brine</td><td>is</td>

<td>regulated</td><td>by</td><td>adjustment valve</td><td>flow, and</td><td>is regulated</td><td>to the</td>

<td>flow of</td><td>the</td><td>brine flowing in</td><td>the area</td><td>higher</td><td>of the</td>

<td>circuit</td><td>from</td><td>brine. Thus,</td><td colspan="2">the first part</td><td>of the</td>

<td colspan="4">heat exchanger can be formed only</td><td>in the</td><td>area</td>

<td>lower</td><td>from</td><td>the exchange pipe</td><td>of heat</td><td colspan="2">So, as in</td>

the configuration (6), the frost attached can be eliminated through sublimation with the coolant of CO2 can circulate naturally by the effect of thermosiphon.

Therefore, the frost attached to the cane of the heat exchange pipe can be eliminated by sublimation even in a known cooling device in which a heating pipe for the circulation of the hot brine is arranged throughout the entire area of ​​the heat exchange pipe in the upper and lower direction such as the device described in Patent Document 3, With a simple arrangement to add the flow adjustment valve in the heat exchange pipe.

In some modalities, the configuration (5) also includes:

(8) a first temperature sensor and a second temperature sensor that are respectively arranged at an inlet and outlet of the brine circuit to detect a temperature of the brine flowing through the inlet and outlet.

In configuration (8), a small difference between the detected values ​​of the two temperature sensors indicates that the melted amount of the frost is reduced, and the thaw is almost finished. The timing at which the defrosting operation is completed can be determined precisely by obtaining the difference between the detected values ​​of the two temperature sensors because the sensible heating is carried out in the heat exchanger part with the brine. Therefore, excessive heating in the freezer or diffusion of water vapor due to excessive heating can be avoided, and in addition to energy saving it can be achieved. In addition, a stable temperature in the freezer can be achieved, so that the quality of frozen food products in the freezer can be improved.

In some embodiments, in configuration (1), (9) the pressure adjustment unit includes:

a pressure sensor to detect the pressure of the CO2 refrigerant circulating in the closed circuit;

a valve pressure disposed in the outlet path of the adjustment heat exchange pipe; and a control device for receiving a detected sensor value? pressure, and controlling an opening of the pressure adjustment valve in such a way that the condensation temperature of the CO2 refrigerant circulating in the closed circuit becomes equal to or less than the point of water vapor in the indoor air of the freezer in the freezer.

In configuration (9), the control device can precisely control the pressure of the CO2 refrigerant circulating in the closed circuit.

In some embodiments, in configuration (1), (10) the cooling device includes:

a primary refrigerant circuit in which the NH3 refrigerant circulates and a refrigeration cycle component is arranged;

a secondary refrigerant circuit in which the refrigerant circulates CO2, the secondary refrigerant circuit led to the refrigeration device, the secondary refrigerant circuit is connected to the primary refrigerant circuit through a cascade condenser; and a liquid CO2 receiver to store the liquefied CO2 refrigerant in the cascade condenser and a liquid CO2 pump to send the CO2 refrigerant stored in the liquid.

In the configuration (10), in the refrigeration device, natural refrigerants of NH3 and CO2 are used, and therefore an attempt is made to avoid depletion of the ozone layer, global heating, and the like. In addition, the cooling device uses NH3, with high cooling performance and toxicity, as a primary refrigerant and uses CO2, without toxicity or odor, as a secondary refrigerant, and therefore can be used for air conditioning of the room and to refrigerate food products and like, maintaining superior cooling performance.

In some embodiments, in configuration (1), (11) the refrigeration device is an NH3 / CO2 cascade refrigeration device including: a primary refrigerant circuit in which the NH3 refrigerant circulates and a component of refrigeration cycle; and a secondary refrigerant circuit in which the CO2 refrigerant circulates and a refrigeration component cycle is arranged, the secondary refrigerant circuit led to the cooling device, the secondary refrigerant circuit is connected to the primary refrigerant circuit through a cascading condenser

In the configuration (11), in the refrigeration device, the natural refrigerant is used, and therefore an incense is provided to avoid depletion of the ozone layer, global heating, and the like. In addition, the refrigeration device uses CO2, without toxicity or odor, as a secondary refrigerant, and therefore can be used for room air conditioning and refrigeration for food products and the like while maintaining high cooling performance. . The

<td>device</td><td>from</td><td>refrigeration</td><td>it is</td><td>a</td><td>device</td><td>from</td>

<td>refrigeration</td><td>in</td><td>waterfall, and by</td><td>the</td><td>so much</td><td>can have</td><td>COP</td>

<td>higher.</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>In</td><td colspan="2">some modalities,</td><td>the</td><td colspan="2">configuration (10]</td><td> ) 0</td>

(11) also includes:

a cooling water circuit resulted in a condenser provided as part of the refrigeration cycle component disposed in the primary refrigerant circuit, and the second part of], heat exchanger is a part of the heat exchanger to which the cooling water circuit and brine circuit, the heat exchanger part configured to heat the brine circulating in the brine circuit with water heated by the cooling condenser.

In the configuration (12), the brine can be heated with hot cooling water, and therefore no heat source is required outside the cooling apparatus.

The temperature of the cooling water can be lowered by the brine during the defrosting operation, so that the condensation temperature of the NH3 refrigerant can be lowered during the cooling operation, and the COP of the cooling device can be improved. In an exemplary embodiment where the cooling water circuit is arranged between the condenser and a cooling tower, the second heat exchanger part may be arranged in the cooling tower. Therefore, a space where the device used for defrosting can be reduced in size.

In some configuration modes (10) or (11) it also includes:

(13) a cooling water circuit resulted in a condenser provided as part of the refrigeration cycle component disposed in the primary refrigerant circuit; and a cooling tower to cool the cooling water circulating in the cooling water circuit by exchanging heat between the water spray and cooling water, and the second part of the heat exchanger includes a heating tower to receive Water spray and heat exchange between the brine circulating in the brine circuit and the spray water, the heating tower is integrally formed with the cooling tower.

In the configuration (13), the heating tower is integrally formed with the cooling tower, whereby a space in which the second part of the heat exchanger is installed can be reduced in size.

(14) A sublimation defrost method according to at least one embodiment of the present invention includes:

a first step of dehumidifying the interior air of the freezer in the freezer with the dehumidifying device so that a partial pressure of the water vapor in the interior air of the freezer does not become a partial pressure of saturated steam;

a second stage of closing the on-off valve at the time of defrosting to form the closed circuit;

a third stage of adjusting the pressure of the CO2 refrigerant circulating in the closed circuit so that the condensation temperature of the CO2 refrigerant is made equal to or less than the point of water vapor in the freezer's indoor air in the freezer of freezing; and a fourth stage of vaporization of the CO2 refrigerant by exchanging heat between the brine as a heating medium and the CO2 refrigerant circulating in the closed circuit; and a fifth stage of allowing the vaporized CO2 refrigerant in the fourth step to circulate in the closed circuit, and the removal of frost bonded on an outer surface of the heat exchange pipe by sublimation with the heat of the CO2 refrigerant.

In the configuration (14), the frost attached to the outer surface of the heat exchange pipe is heated by the heat of the CO2 refrigerant flowing in the heat exchange pipe, and therefore the entire area of ​​the pipe Heat exchange can be heated evenly. The pressure in the closed circuit is adjusted, so that the condensation temperature of the CO2 refrigerant is controlled, so that the temperature of the CO2 refrigerant gas flows in the closed circuit can be precisely controlled. Therefore, the frost can be accurately heated to a temperature equal to or less than the freezing point, whereby sublimation defrosting can be achieved.

As described above, the frost attached to the heat exchange pipe does not melt but is sublimated, and therefore a drain pan and an installation for the discharge of accumulated drain into the drain pan is not required, so that the cost of the refrigeration apparatus can be greatly reduced. The frost attached to the heat exchange pipe is heated from the inside through a pipe wall of only the heat exchange pipe. Therefore, heat exchange efficiency can be improved and energy saving can be achieved.

In some embodiments, in configuration (14) (15) in the fourth step, brine and CO refrigerant₂ circulating in the closed heat exchange circuit in the lower zone of the closed circuit provided with a difference in elevation, and in the fifth stage, the CO refrigerant₂ It is allowed to circulate naturally in the closed circuit by a thermosiphon effect.

In the configuration (15), the CO refrigerant₂ it is allowed to circulate naturally in the closed circuit by the effect of thermosiphon, which does not require a

7 unit to force the circulation of the CO refrigerant ?, and cost reduction can be achieved.

Advantageous effects

According to at least one embodiment of the present invention, sublimation of defrosting of the frost attached to the surface of the heat exchange pipe of the cooling device can be achieved. Therefore, the drain pan and a drain discharge facility are not required. In addition, no drain discharge operation is required, thereby reducing the initial operating costs and required for defrosting, and energy saving can be achieved.

SHORT DESCRIPTION

OF THE DRAWINGS

The Figure is a system diagram of a refrigeration apparatus according to one embodiment.

Figure 2 is a system diagram of a refrigeration apparatus according to one embodiment.

Figure 3 is a cross-sectional view of a refrigeration device of the refrigeration apparatus shown in Figure 2.

Figure 4 is a cross-sectional view of a cooling device according to one embodiment.

Figure 5 is a system diagram of a refrigeration apparatus according to one embodiment.

Figure 6 is a cross-sectional view of a refrigeration device of the refrigeration apparatus shown in Figure 5.

Figure 7 is a system diagram of a refrigeration apparatus according to one embodiment.

Figure 8 is a system diagram of a refrigeration apparatus according to one embodiment.

Figure 9 is a system diagram of a refrigeration apparatus according to one embodiment.

Figure 10 is an arrangement diagram of a refrigeration apparatus according to one embodiment.

DETAILED DESCRIPTION

The embodiments of the present invention shown in the accompanying drawings will now be described in detail. It is intended, however, that the dimensions, materials, shapes, relative positions, and the like of components described in the embodiments will be construed as illustrative only and not limiting the scope of the present invention unless otherwise specified. For example, expressions that indicate a relative or absolute arrangement such as in a certain direction, along a given direction, parallel to, orthogonal to, center of, concentric to, and coaxially not only strictly indicate such arrangements but also indicate a state including a tolerance or relative displacement within an angle and a distance achieve the same function.

For example, expressions such as the same, equal, and equivalent to what indicates a state in which the objects are the same, not only strictly indicate the same state, but also indicate a state that includes a tolerance or difference to achieve same function.

For example, expressions that indicate shapes such as rectangular and cylindrical not only indicate shapes, such as rectangular and cylindrical in a geometrically strict sense, but also indicate shapes including depressions / protrusions, chamfered portions, and the like, as long as you can Get the same effect.

Expressions such as comprising, including, including, provided, or having a certain component are not exclusive expressions that exclude other components.

Figure 1 to Figure 9 shows the defrosting systems for refrigeration appliances in accordance with some embodiments of the present invention.

The refrigeration apparatus 10A to 10D in these embodiments include: cooling devices 33a and 33b, respectively, arranged in freezers 30a and 30b;

HA and 11B refrigeration devices that cool and liquefy the CCt refrigerant; and a refrigerant circuit (corresponding to the secondary refrigerant circuit 14) that allows the cooled and liquefied CO2 refrigerant in the refrigeration devices to circulate to the cooling devices 33a and 33b. The cooling devices 33a and 33b, respectively, include: housings 34a and 34b; and heat exchanger tubes 42a and 42b arranged in the housings. The internal temperature of the freezers 30a and 30b is kept as low as -25 ° C, for example in the refrigeration apparatus 10A to 10D shown in Figure 1 to Figure 9 during a refrigeration operation.

In the exemplary configurations of the embodiments, the heat exchange pipes 42a and 42b were directed to the housings 34a and 34b from the outside of the housings 34a and 34b. Here, the tube areas of the heat exchanger 42a and 42b outside the partition walls of the housings 34a and 34b and the interior of the freezers 30a and 30b are known as an inlet pipe 42c and an outlet pipe 42d.

Dehumidifying devices 38a and 38b for dehumidifying the freezer's indoor air are arranged in freezers 30a and 30b. Dehumidifying devices 38a and 38b are adsorption dehumidifying devices in some embodiments shown in Figure 1 to Figure 9. For example, the adsorption dehumidifier device is a rotor desiccant dehumidifier device including a rotating rotor that has adsorbent on its surface, and continuously and simultaneously performs a step of adsorbing water vapor from the freezer interior air to a partial area of ​​the rotating rotor and a stage of separation of water vapor adsorbed with other areas. External air is supplied to dehumidifying devices 38a and 38b. Dehumidifying devices 38a and 38b absorb water vapor and are discharged to the outside, and cold dry air discharges d into the freezer.

A CO2 circulation path is formed from a circulation path formation path connected to the inlet tube 42c and the outlet pipe 42d of the heat exchange pipes 42a and 42b. The path of the path formation is defrost circuits 50a and 50b connected to the inlet tube and the outlet pipe of the heat exchange pipes 42a and 42b in the modalities shown in Figure 1 and Figure 9, and bypass pipes 72a and 72b connected to the inlet pipe and the pipe. outlet of heat exchange pipes 42a and 42b in the modalities shown in Figure 2 to Figure 6. An on-off valve to form the CO2 circulation path converted into a closed circuit at the time of defrosting is arranged in each of the inlet pipe 42c and the outlet pipe 42d of the heat exchange pipes 42a and 42b. In some embodiments shown in Figure 1 to Figure 9, the on / off valve are on and off solenoid valves 54a and 54b.

In the example of configurations of the modalities shown in Figure 1 to Figure 9, two air openings are formed in the housings 34a and 34b. The fans 35a and 35b are arranged in one of the openings. A flow of air flowing in and out of the housings 34a and 34b is formed by an operation of the fans 35a and 35b. Heat exchange pipes 42a and 42b have a winding shape in a horizontal direction and an upper and lower direction, for example.

Pressure adjustment units 45a and 45b are arranged for the storage spacing pressure of a CO refrigerant₂ circulating in the closed circuit at the time of defrosting. C0 refrigerant pressure₂ in the closed circuit it is adjusted by the set pressure of units 45a and 45b so that the CO2 refrigerant has a higher condensation temperature than a freezing point (for example, 0 ° C) of water vapor in the air inside in freezers 30a and 30b, at the time of defrosting.

In the illustrative configurations of some embodiments shown in Figure 1 to Figure 9, the set pressure of units 45a and 45b, respectively, include: pressure sensors 46a and 46b to detect the pressure of the CO2 refrigerant circulating in the closed circuit; regulating valves 48a and 48b arranged in the outlet pipe 42d of pressure; and the control devices 47a and 47b that receive detected values ​​from the pressure sensors 46a and 46b, and the control valve opens the pressure adjustment valves 48a and 48b so that the CO2 refrigerant pressure is controlled in such a way so that the condensation temperature of the CO2 refrigerant circulating in the closed circuit becomes greater than a freezing point of water vapor in the indoor air in the freezer 30a and 30b.

In the example configuration of the mode, the pressure of the regulating valves 48a and 48b are arranged in parallel to the solenoid on-off valves 52a and 52b.

The pressure sensors 46a and 46b are arranged in the outlet pipe 42d on the upstream side of the pressure of the regulating valves 48a and 48b. The control devices 47a and 47b control the outlet opening of the pressure valve regulation 48a and 48b and therefore adjust the pressure of the CO2 refrigerant according to the detected values ​​of the pressure sensors. Therefore, the condensation temperature of the CO2 refrigerant circulating in the closed circuit becomes equal to or less than the freezing point of the water vapor in the indoor air in the freezer freezers 30a and 30b.

When solenoid on-off valves 52a and 52b close at the time of defrosting so that the CO2 circulation path becomes a closed circuit, a circulation unit allows the CO refrigerant₂ circulate in the closed circuit. The circulation unit is a liquid pump arranged in the CO circulation path₂ for example. Alternatively, the circulation unit may allow the C0 refrigerant₂ circulate naturally by a thermosiphon effect as in some modalities shown in Figure 1 to Figure 10, instead of forcing the circulation of the refrigerant.

Brine is used as a heating medium. A first heat exchanger part is available that heats the CO refrigerant₂ circulating in the CO circulation path₂ with the brine, and thus the refrigerant evaporates. The first part of the heat exchanger are parts of the heat exchanger 70a and 70b to which brine bypass circuits 61a and 61b were carried, branched from defrost circuits 50a and 50b and a brine circuit 60, in the modalities shown in Figure 1 and Figure 9. The heat exchanger part in the embodiments shown in Figure 2 to Figure 6 includes the lower zones of heat exchange tubes 42a and 42b and brine circuits derived 63a and 61b or 80a and 80b led to the lower zones.

An aqueous solution such as ethylene glycol or propylene glycol can be used as brine, for example.

In the modalities shown in the

Figure 1 and the

Figure 9, the flow path that forms the path is provided with the defrost circuits 50a and 50b, as well as the parts of the heat exchanger 70a and 70b as the first part of the heat exchanger.

In the modalities shown in Figure 2 a

Figure 6, bypass tubes 72a and 72b are arranged as the path of trajectory formation circulation, and the heat exchanger part that includes the lowest zones of the heat exchanger pipes 42a and 42b and brine bypass circuits 61a and 61b led to

<td>the zones</td><td>plus</td><td>casualties is formed</td><td>as part</td><td>from</td><td>exchanger</td><td>from</td>

<td>hot.</td><td>In</td><td>the modalities</td><td>shown</td><td>in</td><td>Figure 1 a</td><td>the</td>

<td>Figure 9,</td><td>the</td><td>trajectory of</td><td>circulation</td><td>from</td><td colspan="2">CO2 is provided</td>

of a difference in elevation in the upper and lower direction, and the first part of the heat exchanger is formed in the lower zone of the CO2 circulation path. More specifically, in the modalities shown in Figure 1 and Figure 9, the CO2 circulation path is provided with the difference in elevation because defrost circuits 50a and 50b are arranged below cooling devices 33a and 33b In the

<td>modalities</td><td colspan="2">shown in the</td><td>Figure 2</td><td>to the Figure</td><td> 6,</td><td>the</td>

<td>pipes of</td><td colspan="2">exchanger</td><td>heat 42a</td><td colspan="2">and 42b that form</td><td>the</td>

<td>trajectory</td><td>from</td><td colspan="2">CO2 circulation is</td><td>provides</td><td>with</td><td>a</td>

<td colspan="2">difference in In the</td><td>elevation. trajectory</td><td colspan="2">CO2 circulation</td><td>with</td><td>the</td>

<td>difference</td><td>from</td><td>elevation,</td><td>It can</td><td>allow</td><td>what</td><td>the</td>

<td>refrigerant</td><td>from</td><td>CO2 circulate in</td><td colspan="3">the closed circuit formed</td><td>in</td>

the moment of defrosting by the thermosiphon effect. More specifically, the CO2 refrigerant gas vaporized by the first part of the heat exchanger rises due to the thermosiphon effect. The CO2 refrigerant gas that has raised heat exchange with the frost that has been attached to an outer surface of the heat exchanger part in the heat exchange pipes 42a and 42b or from an upper area of ​​the heat pipe heat exchange, and therefore eliminates frost by sublimation. CO refrigerant₂ It liquefies by eliminating potential heat. The liquefied CCt refrigerant descends on the CO2 circulation path with gravity. Therefore, a loop thermosiphon effect is obtained, and the CO refrigerant is allowed₂ circulate naturally in the closed circuit.

In some embodiments shown in Figure 1 to Figure 6, a second heat exchanger part (corresponding to heat exchanger part 58) is arranged to cause heat exchange between the brine and the heating medium (cooling water ) to heat the brine, and a brine circuit 60 (illustrated in dashed line) to cause the brine heated by the second part of the heat exchanger to circulate to the first part of the heat exchanger. The brine bypass circuit 60 is bypass circuits 61a and 61b (illustrated in broken lines) outside the freezers 30a and 30b. In the embodiments shown in Figure 1 and Figure 9, the brine branching circuits 61a and 61b lead to the heat exchanger parts 70a and 70b. In the embodiments shown in Figure 2 to Figure 6, the brine bypass circuits 61a and 61b are connected to the brine bypass circuits 63a and 63b or 80a and 80b (illustrated in dotted line) arranged in freezers 30a and 30b, through a contact part 62.

At least one embodiment is shown in Figure 2 and Figure 3, the heat exchange pipes 42a and 42b are arranged with the difference in elevation in the cooling devices 33a and 33b.

The brine bypass circuits 63a and 63b are conducted to the cooling devices 33a and 33b and are arranged in the lower zones of the heat exchange pipes 42a and 42b. For example, the brine bypass circuits 63a and 63b are arranged in the lower zones, which are 1/3 to 1/5 of an area in which the heat exchange pipes 42a and 42b are arranged.

The first part of the heat exchanger is formed between the brine bypass circuits 63a and 63b and the lower zones of the heat exchange pipes 42a and 42b.

In the configuration example of the cooling device 33a shown in Figure 3, the air holes are formed in the upper and side surfaces (not shown) of the housing 34a, and the internal air freezer C flows through the surface lateral and flows outward through the upper surface.

In the configuration example of the cooling device 33a shown in Figure 4, the air holes are formed on both side surfaces, and the indoor air freezer c flows in and out of the housing 34a through both side surfaces.

In at least one embodiment shown in Figure 5 and Figure 6, the heat exchange pipes 42a and 42b and the brine bypass circuits 80a and 80b are arranged in the cooling devices 33a and 33b, with the difference in elevation . The brine bypass circuits 80a and 80b are configured such that the brine flows from a lower side to an upper side. The flow adjustment valves 82a and 82b are arranged in intermediate positions of the brine bypass circuits 61a and 61b in the upper and lower direction. In this configuration, the outlet opening of the valve flow adjustment 82a and 82b is narrowed, so that the first part of the heat exchanger can be formed in the lateral areas upstream of the flow adjustment of

<td>82a valves</td><td>and 82b,</td><td>that is, the pipes</td><td>from</td><td>exchange</td><td>from</td>

<td>heat 42a and</td><td>4 2b in</td><td>the bottom side of the</td><td colspan="2">flow valves</td><td>from</td>

<td>fit 82a and In</td><td>82b some</td><td>modalities shown</td><td>in</td><td>Figure 1</td><td>to</td>

Figure 9, the temperature sensors 66 and 68 are respectively arranged in an inlet and an outlet of the brine circuit 60. The temperature of the brine flowing through the inlet and outlet can be measured by the temperature sensors. It can be determined that defrosting is almost complete when the difference between the detected value of the temperature sensor is small. Therefore, a threshold (2 to 3 ° C for example) can establish the difference between the detected values, and it can be determined that defrosting is completed when the difference between the detected values ​​decreases to or below the threshold. In the modalities shown in Figure 2 to Figure 6, a receiver (open brine tank) 64 that temporarily stores the brine and a brine pump 65 for brine circulation are arranged in an emission path of the brine circuit 60. In the mode shown in Figure 9, an expansion tank 92 to absorb the pressure change and the brine flow adjustment, is disposed in the place of the receiver 64.

In some embodiments shown in Figure 1 to Figure 6, the cooling devices 10a to 10c include the cooling device lia. The cooling device lia includes a primary refrigerant circuit 12 in which an NH3 refrigerant circulates and a refrigeration cycle component is arranged, and a secondary refrigerant circuit 14 in which the CO2 refrigerant circulates. The secondary refrigerant circuit 14 extends to the cooling devices 33a and 33b. The secondary refrigerant circuit 14 is connected to the primary refrigerant circuit 12 through a cascade condenser 24. The refrigeration cycle component disposed in the primary refrigerant circuit 12 includes a compressor 16, a condenser 18, a liquid NH3 receiver 20 , an expansion valve 22, and the cascade condenser 24.

The secondary refrigerant circuit 14 includes a liquid CO2 receiver 36 in which a liquid CO2 refrigerant that is liquefied by the cascade condenser 24 is temporarily stored, and a liquid CO2 pump 37 that allows the stored liquid CO2 refrigerant in the liquid CO2 receiver 36 circulate it to the heat exchanger tubes 42a and 42b.

A CO2 circulation path 44 is disposed between the cascade condenser 24 and the liquid CO2 receiver 36. The CO2 refrigerant gas introduced into the cascade condenser 24 through the CO2 circulation path 44 from the CO2 receiver liquid 36 is cooled and liquefied by the NH3 refrigerant in the cascade condenser 24, and then returns to the liquid CO2 receiver 36.

In the cooling device lia, natural refrigerants of NH3 and CO2 are used, and therefore an attempt is made to avoid depletion of the ozone layer, global heating, and the like. In addition, the cooling device 11A uses NH3, with high cooling and toxicity performance, as a primary refrigerant and uses CO2, without toxicity or odor, as a secondary refrigerant, and therefore can be used for room air conditioning and to refrigerate food products and the like.

In at least one example of an embodiment shown in Figure 7, the cooling device 11B may be arranged instead of the cooling device 11A. In the cooling device 11B, a lower stage compressor 16b and an upper stage compressor 16a are arranged in the primary refrigerant circuit 12 in which the NH3 refrigerant circulates. An intermediate cooling device 84 is disposed in the primary refrigerant circuit 12 and between the lower stage compressor 16b and the upper stage compressor 16a. A bypass path 12a is derived from the primary refrigerant circuit 12 at an outlet of the condenser 18, and an intermediate expansion valve 86 is disposed at the bypass path 12a. The NH3 refrigerant flowing in the bypass path 12a is expanded and cooled in the intermediate expansion valve 86, and then introduced into the intermediate cooling device 84. In the intermediate cooling device 84, the NH3 refrigerant discharged of the lower stage compressor 16b is cooled with the NH refrigerant₃ introduced from branching path 12a. Providing the intermediate cooling device 84 can improve the COP

<td>(performance coefficient</td><td>of refrigeration)</td><td>of the</td><td>device</td>

<td>of cooling 11B.</td><td></td><td></td><td></td>

<td>Coolant</td><td>of liquid CO2, it</td><td>enf</td><td>laugh and liquefy</td>

<td>exchanging heat with</td><td>the refrigerant</td><td>from</td><td>NH₃ in the</td>

<td>cascade condenser 24,</td><td>It is stored in the</td><td colspan="2">CO receiver₂</td>

liquid 36. Then, the liquid CO2 pump 37 circulates the CO refrigerant₂ liquid in the refrigeration device 33 arranged in the freezer 30, from the liquid CO2 receiver 36.

In at least one example of an embodiment shown in Figure 8, the cooling device 11C may be arranged instead of the cooling device HA. The cooling device 11C forms a cascade refrigeration cycle. A higher temperature compressor 88a and an expansion valve 22a are arranged in the primary refrigerant circuit 12 in which the NH refrigerant circulates₃.

A lower temperature compressor 88b and an expansion valve 22b are arranged in the secondary refrigerant circuit 14 connected to the primary refrigerant circuit 12 through the cascade condenser 24.

The cooling device 11C is a cascade cooling device in which a mechanical compression refrigeration cycle is formed in each of the primary refrigerant circuit 12 and the secondary refrigerant circuit 14, whereby the COP of the cooling device

In some embodiments shown in Figure 1 to Figure 6, the cooling devices 10A to 10C include the cooling device 11A. In the cooling device 11A a cooling water circuit 28 is directed to the condenser 18. A cooling water bypass circuit 56 including the cooling water pump 57 is derived from the cooling water circuit 28. The cooling water bypass circuit 56 and the brine circuit 60 (illustrated in a dotted line) is directed to the cooling water pump 57 as the second part of the heat exchanger.

The cooling water circulating in the cooling water circuit 28 is heated by the NH3 refrigerant in the condenser 18. The heated cooling water serves as a heating means to heat the brine circulating in the brine circuit 60 in the heat exchanger part 58, at the time of defrosting.

When the temperature of the cooling water introduced into the heat exchanger part 58 from the cooling water bypass circuit 56 is from 20 to 30 ° C for example, the brine can be heated to 15 to 20 ° C with this water of cooling.

In another embodiment, any heating medium other than cooling water can be used as the second heating medium. Said heating means includes high temperature and high pressure NH3 refrigerant gas discharged from compressor 16, hot water discharge from a factory, a medium that has absorbed heat emitted from a boiler or potential heat from an oil cooler, and the like .

As an example of configuration of some embodiments, the cooling water circuit 28 is disposed between the condenser 18 and a closed-type cooling tower 26. The cooling water is circulated in the cooling water circuit 28 through the pump of cooling water 29. The cooling water that has absorbed heat from the escape of the NH3 refrigerant in the condenser 18 comes into contact with the outside air in a closed-type cooling tower 26 and is cooled with latent heat of water vaporization.

6

The closed-type cooling tower 26 includes: a cooling coil 26a connected to the cooling water circuit 28; a fan 26b blowing the outside air to the cooling coil 26a; and spray pipe 26c and a pump 26d for spraying the cooling water on the cooling coil 26a. The atomized cooling water of the spray pipe 26c partially evaporates. The cooling water flowing in the cooling coil 26c is cooled by the latent heat of vaporization thus produced.

In at least one embodiment shown in Figure 9, the cooling device 11D disposed in the cooling device 10D includes a closed type cooling and heating unit 90 in which the closed type cooling tower 26 and a closed type heating tower 91. The closed-type cooling tower 26 in the present embodiment cools the cooling water circulating in the cooling water circuit 28 through heat exchange with sprayed water, and has the basic configuration that is the same as that of the closed type cooling tower 26 shown in Figure 1 to Figure 6.

The closed type heating tower 91 receives spray water used for cooling the cooling water circulating in the cooling water circuit 28 in the closed type cooling tower 26, and causes heat exchange between the spray water and brine circulating in brine 60. The closed type heating tower 91 includes: a heating coil 91a connected to the brine circuit 60; and spray pipe 91c and a pump 91d for spraying the cooling water on the cooling coil 91a. An interior of the closed type cooling tower 26 communicates with an interior of the closed type heating tower 91 through a lower portion of a common housing. The

<td>sprayed on</td><td>Water</td><td>what</td><td>has absorbed the</td><td>hot</td><td>exhaust</td><td>of the</td>

<td>refrigerant</td><td>from</td><td>nh₃</td><td>circulating</td><td>in the</td><td>circuit</td><td>from</td>

<td>refrigerant</td><td colspan="2">primary</td><td>12 is sprayed</td><td>in the</td><td>coil</td><td>from</td>

cooling 91a from the spray pipe 91c, and serves as a heating medium that heats the brine circulating in the cooling coil 91a and the brine circuit 60.

In some embodiments shown in Figure 1 to Figure 9, the secondary refrigerant circuit 14 is referred to CO bypass circuits₂ 40a and 40b out of freezers 30a and 30b. C0 bypass circuits₂ 40a and 40b are connected to the inlet tube and the outlet tube of the heat exchange pipes 42a and 42b outside the freezers 30a and 30b.

The brine circuit 60 that extends to a part near the freezers 30a and 30b of the heat exchanger part 58 is derived to the brine bypass circuits 61a and 61b (illustrated in dotted line) outside the freezers 30a and 30b

In the refrigeration apparatus 10A shown in Figure 1, the brine bypass circuits 61a and 61b are conducted to the heat exchange parts 70a and 70b arranged in the freezers 30a and 30b.

Defrost by sublimation is performed in the refrigeration apparatus 10A as follows. Specifically, when the freezer indoor air in freezers 30a and 30b has saturated the water vapor pressure, the dehumidifier devices 38a and 38b are operated so that the dehumidification reaches the partial low water vapor pressure. Then, solenoid on-off valves 52a and 52b are closed so that the CO2 circulation path, including heat exchange pipe 42a and 42b and defrost circuits 50a and 50b, becomes the closed circuit.

The detected values ​​of the pressure sensors 46a and 46b are entered in the control devices 47a and 47b. The control devices 47a and 47b operate the valve regulating pressure 48a and 48b with the values ​​detected to adjust the pressure of the CO2 refrigerant circulating in the closed circuit so that the condensation temperature of the CO2 refrigerant becomes the same or less than the freezing point (for example, 0 ° C) of water vapor in the freezer inside. For example, the CO2 refrigerant has risen to 3.0 MPa (temperature of -5 ° C condensation).

Next, the CO2 refrigerant is evaporated by heat exchange between the brine and the CO2 refrigerant in the heat exchanger parts 70a and 70b. Then, the vaporized CO2 refrigerant is circulated in the closed circuit, whereby the frost attached to the outer surface of the heat exchange pipes 42a and 42b are removed through sublimation with the latent heat of condensation (249 kJ / kg at -5 ° C / 3.0 MPa) of the CO2 refrigerant. The lower limit value of the condensation temperature of the CO2 refrigerant is set for the sublimation of the frost is an inside freezer temperature (for example, -25 ° C). During the refrigeration operation, the CO2 refrigerant at a temperature equal to or less than the freezer inside temperature (for example, -30 ° C) is allowed to circulate in the heat exchanger pipes 42a and 42b to cool in the freezer . Therefore, the temperature of the frost is equal to or lower than the inside temperature of the freezer (for example, -25 ° C to -30 ° C), consequently, sublimation of frost by heating can be achieved when the temperature of CO refrigerant condensation₂ It is within a range of the freezer's internal temperature and the point of water vapor in the freezer at the time of sublimation defrosting.

In the present embodiment, defrost circuits 50a and 50b are arranged below heat exchange tubes 42a and 42b, and the CO circulation path₂ It has the difference of elevation. Therefore, the vaporized CO refrigerant₂ in the heat exchanger parts 70a and 70b it rises to the heat exchanger tubes 42a and 42b due to the thermosiphon effect. Therefore, the frost attached to the outer surfaces of the heat exchange pipes 42a and 42b is sublimated and therefore liquefied by the potential heat of the C0 refrigerant gas₂ which has been conducted to heat exchange pipes 42a and 42b. CO refrigerant₂Liquified descends in defrost circuits 50a and 50b with gravity, and then evaporates again in the part of heat exchanger 70a and 70b.

In the refrigeration apparatus 10B shown in Figure 2 and Figure 3 and in the refrigeration apparatus 10C shown in Figure 5 and Figure 6, the heat exchange pipes 42a and 42b, as well as the brine bypass circuits 63a and 63b or 80a and 80b are arranged in cooling devices 33a and 33b with the difference in elevation.

Bypass pipes 72a and 72b are connected between the inlet pipe and the outlet pipe of the heat exchange pipes 42a and 42b outside the housings 34a and 34b. Solenoid on-off valves 74a and 74b are disposed in bypass pipe 72a and 72b. In the inlet pipe, solenoid on-off valves 54a and 54b are arranged on the upstream side of the bypass pipes 52a and 52b. In the outlet pipe, solenoid ignition valves 54a and 54b are arranged on the downstream side of the bypass pipes 52a and 52b.

In the cooling apparatus 10B, the brine bypass circuits 63a and 63b are conducted to the lower zones of the heat exchange pipes 42a and 42b. The part of the heat exchanger is formed by the low zones of heat exchanger pipes 42a and 42b and the brine bypass circuits 63a and 63b.

In the cooling apparatus 10C, the brine bypass circuits 80a and 80b are arranged substantially over the entire area of ​​the area where the heat exchanger pipes 42a and 42b are arranged. The flow rate adjustment valves 82a and 82b are arranged in intermediate portions of the brine bypass circuits 80a and 80b in the upper and lower direction. Brine bypass circuits 80a and 80b form a flow path in which the brine flows to an upper area of ​​a lower zone.

In an example of configuration of the cooling devices 33a and 33b, for example, as in the cooling device 33a is shown in Figure 3 or Figure 6, the heat exchange pipes 42a and 42b, as well as the circuit of Brine bypass 63a and 63b or 80a and 80b have the winding shape and are arranged in the horizontal direction and in the upper and lower direction. The brine-derived circuits 80a and 80b form the flow path in which the brine flows to an upper area of ​​a lower zone.

The heat exchange pipe 42a includes heads 43a and 43b in the inlet pipe 42c and 42d of the outlet pipe, outside the cooling device 33a. Brine bypass circuits 63a and 80a include heads 78a and 78b at one inlet and one outlet of the cooling device 33a.

A large number of fin plate 76a is arranged in the upper and lower direction 33a in the cooling device. The heat exchange pipe 42a and the bypass circuit 63a or 80a are inserted into a large number of holes formed in the fin plate 76a and therefore sor. compatible with plate fins 76a. With the plate fins 76a, which withstand the increasing resistance for the pipes, and the heat transmission between the heat exchange pipe 42a and the brine bypass circuit 63a or 80a is facilitated.

During the cooling operation, the fan 35a diffuses internal air from the freezer c cooled in the cooling device 33a in the freezer 32a. Because no dissolved water is produced at the time of defrosting, a drain pan is not arranged under the housing 34a. The configuration of the cooling device 33a described above is the same as that of the cooling device 33b.

In the cooling devices 11B and 11C, the inlet pipe 42c and the outlet pipe 42d of the heat exchange pipes 42a and 42b are connected to the CO-derived circuits₂ 40a and 40b through the contact part 41, outside the freezers 30a and 30b. The brine bypass circuits 63a, 63b, 80a, and 80b are connected to the brine bypass circuits 61a and 61b through the contact part 62, outside the freezers 30a and 30b. In the cooling apparatus 10b, the housings 34a and 34b of the freezers 30a and 30b, the heat exchanger pipes 42a and 42b including the

4 inlet pipe 42c and outlet pipe 42d, brine bypass circuits 63a and 63b, and bypass pipes 72a and 72b form the cooling units 31a and 31b that are integrally formed.

<td>In the</td><td>apparatus of</td><td>10C cooling</td><td>, the housings</td>

<td>34a and 34b of</td><td colspan="3">the freezers 30a and 30b, the pipes of</td>

<td>exchanger</td><td>heat 42a and</td><td>42b including</td><td>the pipe of</td>

<td>entry 42c and</td><td>The pipe</td><td>42d output,</td><td>circuits of</td>

<td>derivation of</td><td>brine 80a</td><td>and 80b, and the</td><td>pipes of</td>

<td>bypass 72a</td><td>and 72b form</td><td>the units of</td><td>refrigeration</td>

32a and 32b that are integrally formed.

The cooling units 31a and 31b or 32a and 32b are formed detachably connected to the CO bypass circuits₂ 40a and 40b and the brine bypass circuits 61a and 61b through the contact parts 41 and 62.

In cooling devices 10B and 10C, solenoid on-off valves 74a and 74b are closed, and solenoid on-off valves 52a and 52b open during the cooling operation. Solenoid on-off valves

<td>74a and 74b</td><td>they open, and</td><td>the</td><td>valves</td><td>from</td><td>on off</td><td>from</td>

<td>solenoid</td><td>52a and 52b</td><td>I know</td><td>they close</td><td>in</td><td>the moment of</td><td>the</td>

defrosting, so the closed circuit is formed

5 including heat exchanger pipes 42a and 42b and bypass pipes 72a and 72b.

In the refrigeration apparatus 10B, the CO2 refrigerant is evaporated by the potential heat of the brine flowing in the brine bypass circuits 63a and 63b, in the lower zones of the heat exchange pipes 42a and 42b, in the time of defrosting. The vaporized CO2 refrigerant rises to the upper areas of the heat exchange pipes 42a and 42b, and eliminates frost attached to the outer surfaces of the heat exchange pipes 42a and 42b in the upper areas, by sublimation. The refrigerant that has humidified CO2 through sublimation of the frost is liquefied and descends by gravity, and evaporates again in the lower zone. Therefore, the CO2 refrigerant is circulated naturally in the closed circuit by the thermosiphon effect.

In the refrigeration apparatus 10C, at the time of defrosting, the opening of the flow adjustment of the valves 82a and 82b are narrowed so that the brine flow b is restricted. Therefore, the part of heat exchanger in which the CO2 refrigerant and heat exchange brine can be formed only in the upstream zone (lower zone) of the flow valve setting 82a and 82b.

<td></td><td>By</td><td>the</td><td>as he</td><td>CO refrigerant₂ I know</td><td>make</td>

<td>circular</td><td>from</td><td>shape</td><td>natural by</td><td>the thermosiphon effect</td><td>and the</td>

<td>Frost</td><td>I know</td><td>may</td><td>remove</td><td colspan="2">through sublimation by the</td>

Potential heat of the circulating CO2 refrigerant, between the areas of the heat exchange pipes 42a and 42b corresponding to that of the downstream and upstream zones the valve flow setting 82a and 82b.

In accordance with some embodiments shown in Figure 1 to Figure 10, the frost attached to the outer surfaces of the heat exchange pipes 42a and 42b is heated by the heat of the CO2 refrigerant flowing in the heat exchange pipe , whereby uniform heating can be achieved in the area of ​​the pipe entering the heat exchanger. The condensation temperature of the CO2 refrigerant is controlled by adjusting the pressure in the closed circuit. Therefore, the temperature of the CO2 refrigerant gas flowing in the closed circuit can be precisely controlled, so that the frost can be heated to a temperature at or above the freezing point with precision, so it can be achieve defrosting by sublimation.

The fans 35a and 35b are operated at the time of defrosting, so that the flow of air flowing in and out of the covers 34a and 34b is formed, so sublimation can be facilitated.

Therefore, the frost attached to the heat exchange pipes 42a and 42b does not melt but is sublimated, and therefore a drain pan and an installation for the discharge of the accumulated drain into the drain pan is not required, So the cost of the appliance refrigeration can be greatly reduced. The frost attached to the heat exchange pipes 42a and 42b is heated from the inside through a wall of the pipe of only the heat exchange pipe. Therefore, heat exchange efficiency can be achieved and energy saving can be improved.

Defrosting can be achieved with the CO refrigerant₂ in a state of low pressure. Therefore, a pipe system device such as the flow path of C0₂ It does not need to be pressure resistant, so a high cost is not required.

Thus, with the defrost by sublimation achieved, a microchannel heat exchange pipe can be used, which is considered to be difficult to apply to the cooling device for a freezer due to the high performance degradation caused by the formation of frost and dew condensation This technique can be applied not only to the freezer, but it can also be applied to a defrosting method for a batch freezing chamber a freezer that requires non-continuous defrosting operation for a long period of time.

In the refrigeration apparatus 10A shown in Figure 1, defrost circuits 50a and 50b are arranged to form the CO circulation path₂, so that the first part of the heat exchanger formed in the circulation of CO₂. The trajectory can be arranged more freely. In the refrigeration apparatus 10B, the flow path of CO is shown in Figure 2 and Figure 3₂ it is formed of heat exchange pipes 42a and 42b, except for bypass pipes 72a and 72b, and therefore there is no need to additionally provide new pipes, so a high cost is not required.

In some embodiments shown in Figure 1 to Figure 9, the CO refrigerant₂ It can be allowed to circulate naturally in the closed circuit by the effect of thermosiphon. Therefore, a unit for the force that circulates the CO refrigerant₂ in the closed circuit it is not required, and the equipment and the power (pump power) to force the circulation, with which the cost reduction can be achieved. The brine circuit 60 is provided, and can be discarded according to an arrangement of the heat exchanger part in which the hot brine exchanges exchange heat with

9 CO2 refrigerant Therefore, a position in which the heat exchanger part is arranged can be determined more freely.

In the embodiments shown in Figure 2 and Figure 3, the heat exchanger part involving the brine is formed by the lower zones of the heat exchange pipes 42a and 42b, and the CO2 refrigerant is allowed to circulate in a manner natural by the effect of thermosiphon. Therefore, no additional pipes other than bypass pipes 72a and 72b are required, and no equipment is required to force circulation. Considering all aspects, the cost of cooling devices 33a and 33b can be reduced. The brine bypass circuits 63a and 63b are not arranged in the upper areas of the heat exchanger pipes 42a and 42b, whereby the power used for the fans 35a and 35b can be formed forms the air flow in the devices cooling 33a and 33b. The cooling performance of lows cooling devices 33a and 33b can be improved by also providing the heat exchange pipe 42a and 42b in an empty space in the upper area.

In the embodiment shown in Figure 5 and Figure 6, the brine bypass circuits 80a and 80b are arranged over all the heat exchanger pipes 42a and 42b in the upper and lower direction, and the brine flow is regulated by the flow adjustment of valves 82a and 82b. Therefore, the heat exchanger part may be formed only in the lower zones of the heat exchange pipes 42a and 42b. Therefore, defrost sublimation can be achieved with a simple arrangement of adding the flow setting of valves 82a and 82b for the known cooling device. In some embodiments shown in Figure 1 of Figure 9, the time at which defrosting is completed can be obtained based on the detected values ​​of the temperature sensors 66 and 68 respectively arranged at the input and output of the brine circuit 60. Therefore, excessive heating in the freezer or diffusion of water vapor because excessive heating can be prevented and energy saving can also be achieved. In addition, a stable temperature in the freezer can be achieved, so that the quality of frozen food products in the freezer can be improved.

In some embodiments shown in Figure 1 to Figure 9, the set pressure of the units 45a and 45b are arranged as a pressure set unit for the CO2 refrigerant circulating in the closed circuit. Therefore, the pressure can be easily adjusted accurately at a low cost. In some embodiments shown in Figure 1 to Figure 5, the cooling water circuit 28 is conducted to the heat exchanger part 58, and the cooling water heated in the condenser 18 is used as the heating means for heating the brine Therefore, no heat source is required outside the refrigeration apparatus. The temperature of the cooling water can be lowered with the brine at the time of defrosting, which can reduce the condensation temperature of the NH3 refrigerant during the cooling operation, and the COP of the refrigeration apparatus can be improved.

The heat exchanger part 58 may be arranged in the closed type cooling tower 26. By which a space where an apparatus used for defrosting is installed can be reduced in size.

In the embodiments shown in Figure 9, heat exchange between the heating medium and the brine takes place in the closed type heating tower 91 formed integrally with the closed type cooling tower 26. Therefore, a space where the second part of the heat exchanger is installed can be reduced in size. By using water spray on the closed-type cooling tower 26 as the heat source for the brine, heat can also be acquired from the outside air. When the cooling apparatus 10D employs an air cooling system, the cooling water can be cooled and the brine can be heated with the outside air as a source of heat, with the heating tower alone. In addition, by using the cooling units 31a, 31b, 32a, and 32b of the configuration described above, the cooling devices 33a and 33b with a defrosting device can easily be connected to the freezers 30a and 30b. When the units are fully assembled in advance, the connection to freezers 30a and 30b is further facilitated.

Figure 10 shows an even other modality. A load handling chamber 100 is disposed adjacent to the freezer 30 of this mode. The freezer 30 includes a plurality of the cooling devices 33 having the configuration described above. For example, the cooling device 33 includes the housing 34, the heat exchange pipe 42, the brine bypass circuits 61 and 63, the branch circuit of COs 40, and the like having the configuration described above.

The freezer 30 and the load handling chamber 100 each incorporate the dehumidifying device 38 as the desiccant humidifier. Dehumidifier device 38 conducts outside air from the

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load 100 is maintained at + 5 ° C for example. An electrical heat insulating door 102 is arranged in an inlet for entering and exiting the freezer 30 of the load handling chamber 100. Therefore, the amount of water vapor entering the freezer 30 when the door is opened / close is minimized. For example, when the freezer 30 cools to a temperature of -25 ° C, and has a volume of 7,500 m³ the absolute humidity is 0.4 g / kg at the relative humidity of 100% and the absolute humidity is 0.1 g / kg at the relative humidity of 25%. Therefore, the amount of controllable water vapor, which is obtained by multiplying the difference in absolute humidity by the volume of the freezer 30, is 2.25 kg. Therefore, defrost sublimation can be easily achieved by adjusting the relative humidity of the freezer's indoor air to 25%.

Industrial applicability

According to the present invention, sublimation defrosting can be achieved, so that the initial and operating costs that are required can be reduced

4 for defrosting in the refrigeration apparatus, and energy saving can be achieved.

List of Reference Signs

10Ά, 10b, 10C, 10D cooling device

HA, 11B, 11C, 11D cooling device primary refrigerant circuit secondary refrigerant circuit compressor

16th upper stage compressor

16b lower stage compressor condenser

NH3 Liquid Receiver

22, 22a, 22b expansion valve

Cascade condenser closed type cooling tower

Cooling water circuit

29, 57 cooling water pump

30, 30a, 30b freezer

31a, 31b, 32a, 32b refrigeration unit

33, 33a, 33c cooling device

34, 34a, 34b housing

35a, 35b fan

CO2 liquid receiver

CO2 liquid pump

38, 38a, 38b dehumidifier device

40, 40a, 40b CO2 bypass circuit

41, 62 contact part

42, 42a, 42b heat exchanger tube

42c junction tube

42d outlet tube

43a, 43b, 78a, 78b head

CO2 circulation path

45a, 45b pressure adjustment unit

46a, 46b 47a pressure sensor,

47b control device

48a, 48b pressure regulating valve

50a, 50b defrost circuit

52a, 52b, 74a, 74b solenoid on-off valve cooling water bypass circuit heat exchanger part (second heat exchanger part)

Brine Circuit

61, 61a, 61b, 63, 63a, 63c, 80a, 80b brine derivative circuit receiver brine pump temperature sensor (first temperature sensor) temperature sensor (second temperature sensor) heat exchanger part (first part of heat exchanger)

72a, 72b bypass pipe

76th plate fin

82a, 82b flow adjustment valve intermediate cooling device upper expansion valve

88a intermediate temperature compressor

88b lower temperature compressor closed cooling and heating unit closed type heating tower

92 expansion tank

100 cargo handling chamber

102 heat insulation door b brine c indoor air freezer d air? dry cold