JP2004077039A - Evaporation type condenser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporation type condenser used for an ammonia compression type refrigerator and possible to be made small in size and light in weight. <P>SOLUTION: The evaporation type condenser is provided with a compressor, a condenser and an evaporator and is used for a compression type refrigerator making ammonia as a coolant. A means for spraying cooling water and a means for circulating air are arranged as a means for condensing the ammonia coolant fed from the compressor, and it is characterized by being provided with a plate fin type heat exchanger in which a flow passage circulated with the ammonia coolant and a flow passage circulated with a condensing medium comprising the cooling water and air are superposed and assembled is provided. In this evaporation type condenser, it is desirable that flowing of the ammonia coolant and the condensing medium in the plate fin type heat exchanger is carried out at a crossflow system. Further, it is desirable that a corrugate fin assembled to the flow passage circulated with the condensing medium is made to a herringbone system. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an evaporative condenser suitable for a compression refrigerator, and more particularly, to an improvement in heat exchange efficiency in a condensation process in a refrigeration cycle, which is used in a compression refrigerator using ammonia as a refrigerant. Accordingly, the present invention relates to an evaporative condenser capable of achieving a reduction in size and weight of the apparatus.
[0002]
[Prior art]
As a countermeasure against global warming, the use of CFC-based refrigerants is regulated, and an ammonia compression refrigerator using ammonia as a natural refrigerant as a refrigerant has been attracting attention from the viewpoint of protecting the global environment.
[0003]
FIG. 1 is a schematic diagram showing the entire configuration of the ammonia compression refrigerator. In the compression type refrigerator, basically, a compressor 1, a condenser 2, and an evaporator 3 are provided and connected by a refrigerant pipe 5 to form a refrigeration cycle.
[0004]
In the compressor 1, the ammonia refrigerant is configured to be polytrope-compressed, and in the condenser 2, the compressed ammonia refrigerant undergoes heat exchange with cooling water to become a refrigerant liquid. The liquefied ammonia refrigerant liquid is stored in a high-pressure state in the liquid receiver 2a, is sent out there, is throttled and expanded by an expansion valve 4, is sent to the evaporator 3 at a reduced pressure, and is evaporated as ammonia. I do. Then, when the evaporated ammonia is sucked again by the compressor 1 and compressed, the inside of the evaporator 3 is kept at a low pressure, and the cooling operation is continuously performed.
[0005]
As described below, in the ammonia compression refrigerator, when the ammonia refrigerant compressed by the compressor is supplied from the compressor, the temperature becomes relatively high. For this reason, evaporative condensers that can keep the condensation temperature low are frequently used.
[0006]
FIG. 2 is a diagram showing the overall configuration of a conventional evaporative condenser. As shown in the figure, the entire condenser 2 is covered by a casing 6, and the casing 6 is provided with an air inlet 6a and an outlet 6b. In the casing 6, a heat transfer body 7 through which an ammonia refrigerant flows, a water spray nozzle 8 for spraying cooling water to the heat transfer body 7, an eliminator 9 for preventing water droplets from being scattered outside, and air in the casing Is disposed.
[0007]
The ammonia refrigerant flowing through the heat transfer member 7 is cooled by latent heat of evaporation when the cooling water sprayed from the water spray nozzle 8 to the heat transfer member 7 comes into contact with air flowing upward in the casing 6 and evaporates. The refrigerant is condensed and sent out from the refrigerant outlet 7b. Further, a water tank 11 for storing cooling water and a pump 12 for cooling water are shown in the drawing.
[0008]
[Problems to be solved by the invention]
In a non-CFC-based compression refrigerator using ammonia refrigerant as a natural refrigerant, when the ammonia is compressed by the compressor, the temperature of the ammonia becomes significantly higher than that of the CFC-based refrigerant due to its thermodynamic properties. It becomes overheated. Therefore, the ammonia refrigerant discharged from the compressor is introduced into the condenser at such a high temperature and in an overheated state.
[0009]
Therefore, even if an evaporative condenser is adopted to keep the condensation temperature low, in order to reliably liquefy the high-temperature ammonia refrigerant in the condenser, the capacity of the condenser must be increased in accordance with the overheating state, A large amount of cooling water or cooling air must be supplied. For this reason, since a large amount of energy is consumed in the condensation process of the refrigerant, the evaporative condenser used in the conventional ammonia refrigerator has a large capacity, and the size and weight of the entire refrigeration system cannot be avoided. .
[0010]
The present invention has been made in order to solve the problems in the evaporative condenser used in the ammonia refrigerator described above, and even in a compression refrigerator using an ammonia refrigerant, the heat generated during the condensation process can be reduced. It is an object of the present invention to provide an evaporative condenser capable of achieving a reduction in size and weight of an apparatus by improving the exchange efficiency.
[0011]
[Means for Solving the Problems]
The present inventors have studied in detail the cooling mechanism of the evaporative condenser in order to solve the above-mentioned problem. That is, in the evaporative condenser used in the compression refrigerator, the cooling water sprayed by the spraying means such as the spray nozzle flows down in the form of a film on the surface of the heat transfer body, and removes heat from the high-temperature refrigerant. Evaporate. On the other hand, the air sent by the circulation means such as a blower takes in the evaporated water vapor, becomes high-temperature, high-absolute-humidity air, and is discharged from the upper part of the contractor.
[0012]
Therefore, in the evaporative condenser, cooling water and air are used as a condensing medium, but most of the cooling action is performed by latent heat of evaporation of water. From the viewpoint of heat transfer, the evaporative condenser is an advantageous method because the condensation temperature is low, but it is always necessary to cover the surface of the heat transfer body with a film of cooling water and to ensure the flow of air. become.
[0013]
On the other hand, plate fin type heat exchangers are widely used as heat exchangers for industrial equipment that are small, lightweight, and excellent in heat exchange efficiency. FIG. 3 is a view for explaining the configuration of a laminated assembly (core) in the plate-fin heat exchanger. The core, which is the heart of the heat exchanger, separates a low-temperature fluid passage from a high-temperature fluid passage. A plate-like tube plate 21 and fins 22 of a corrugated type or various shapes for promoting heat transfer are alternately laminated, and a spacer bar 23 for keeping a space between the tube plates 21 and sealing a flow path. Consists of a basic structure arranged on both sides. The arrows in the figure indicate the flow directions of the low-temperature fluid and the high-temperature fluid.
[0014]
When assembling and manufacturing the plate fin type heat exchanger shown in FIG. 3, various components such as the tube plate 21, the fins 22, and the spacer bars 23 are stacked and assembled via a brazing material, and brazed at a high temperature in a vacuum heating furnace. Therefore, the laminated assembly is manufactured integrally. Therefore, since the plate-fin type heat exchanger performs heat exchange through the tube plate 21 in which the low-temperature fluid and the high-temperature fluid partition the flow path, the heat transfer area is large for the size of the device. It has a feature that the device can be reduced in size and weight.
[0015]
The present inventors have focused on the fact that it is effective to employ a plate-fin type heat exchanger to reduce the size and weight of the evaporative condenser having the above-described cooling mechanism, and made various studies. . As a result, it has been found that even with an evaporative condenser used in an ammonia refrigerator, the size and weight of the apparatus can be reduced without lowering the refrigerating performance.
[0016]
The present invention has been completed based on such knowledge, and has the following evaporative condensers of (1) and (2).
(1) A compressor that includes a compressor, a condenser, and an evaporator, is used in a compression refrigerator that uses ammonia as a refrigerant, and sprays cooling water as a unit that condenses the ammonia refrigerant supplied from the compressor. A means for flowing air, and a plate-fin heat exchanger in which a flow path through which the ammonia refrigerant flows and a flow path through which a condensing medium composed of the cooling water and air flows are provided. It is an evaporative condenser characterized by the following.
(2) In the evaporative condenser of the above (1), it is desirable that the flow of the ammonia refrigerant and the condensing medium in the plate fin heat exchanger be performed in a cross-flow type. Further, it is desirable that the corrugated fin incorporated in the flow path through which the condensing medium flows be a herringbone type.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a specific configuration example and operation of the evaporative condenser of the present invention will be described with reference to the drawings.
[0018]
FIG. 4 is a diagram showing the overall configuration of the evaporative condenser of the present invention. The casing 6 covering the entire condenser 2 is provided with an air suction port 6a at a lower portion of a side surface and an air outlet 6b at an upper portion, and an upward air flow path is formed in the casing 6 by driving a blower 10 provided at the air outlet 6b. Is formed. A watering nozzle 8 for spraying cooling water from above is provided so as to face the air flow path, and an eliminator 9 for preventing the sprayed cooling water from scattering outside the casing 6 is provided. Have been.
[0019]
A plate-fin type heat exchanger 20 is disposed at the center of the casing 6 through which the condensing medium composed of the cooling water and the air flows. A water tank 11 for storing cooling water is provided below the casing 6, and the other end of a water supply pipe 13 having one end connected to the water tank is connected to the water spray nozzle 8 via a pump 12.
[0020]
The plate fin type heat exchanger 20 has a structure in which a flow path through which the ammonia refrigerant flows and a flow path through which the condensing medium flows are integrally laminated and assembled, and the ammonia refrigerant supplied from the compressor is The refrigerant flows from the refrigerant inlet 20a, is condensed from the ammonia gas to the refrigerant liquid in the high-temperature fluid flow path in the plate-fin heat exchanger 20, and is supplied to the receiver from the refrigerant outlet 20b.
[0021]
On the other hand, the cooling water sprayed by the watering nozzle 8 is supplied from above to the low-temperature fluid flow passage through which the condensing medium of the plate fin heat exchanger 20 flows, and the entire surface of the flow passage is covered with a cooling water film, Evaporates by removing heat from the refrigerant. Air is supplied to the low-temperature fluid flow path from below, and the water vapor obtained by evaporating the air is taken in and discharged from the upper part of the condenser.
[0022]
As described above, in order for the evaporative condenser to exhibit an appropriate cooling mechanism, it is necessary to always cover the flow path with a film of cooling water and to secure the flow of air. In order to secure these, it is necessary to make the fluid resistance of the sprayed cooling water and the pressure loss of the flowing air appropriate. In order to adjust the fluid resistance of the cooling water and the pressure loss of the air, it is necessary to make the fin height and fin pitch of the corrugated fin incorporated in the high-temperature fluid flow path appropriate.
[0023]
FIG. 5 is a diagram showing a plan configuration of a plate-fin heat exchanger employed in the evaporative condenser of the present invention. As shown in the figure, a high-temperature fluid flow path 24 for an ammonia refrigerant and a low-temperature fluid flow path 25 for a condensing medium are stacked and assembled, and are held by a side plate 26 to form an integral structure.
[0024]
In FIG. 5, in the design example of the evaporative condenser of the present invention, the corrugated fin 22 incorporated in the low-temperature fluid flow path 25 is made of aluminum having a thickness of 0.25 mm, the fin height is 25.4 mm, and the fin height is 25.4 mm. The pitch is 3 fins / 25.4 mm. Although the corrugated fin incorporated in the high-temperature fluid flow path for the refrigerant is not shown, it is made of aluminum having the same thickness, the fin height is 3.2 mm, and the fin pitch is 11 fins / 25.4 mm. be able to.
[0025]
Usually, in order to cover the entire surface of the low-temperature fluid flow path for the condensing medium with the cooling water film, it is effective to make the fin pitch small and the fin height small, but excessively dense fin pitch is effective. When the height of the fins is reduced, the fluid resistance increases and the supply of cooling water is hindered. On the other hand, in order to reduce the pressure loss of the air flowing through the condenser, the fin pitch may be slightly increased to increase the fin height. Therefore, the optimum fin height and fin pitch that satisfy both the predetermined fluid resistance and the pressure loss need to be examined by testing and analysis.
[0026]
The flow method of the low-temperature fluid and the high-temperature fluid inside the plate fin type heat exchanger is basically classified into a countercurrent type and a crossflow type. In the evaporative condenser of the present invention, an arrow in FIG. As shown in the above, it is desirable to use a cross-flow type. This is because the supply width of the low-temperature fluid flow path for the condensing medium can be secured and the pressure loss of air can be reduced by making the flow direction of the high-temperature fluid for the refrigerant orthogonal to the flow direction.
[0027]
As mentioned above, the plate fin type heat exchanger is assembled at the time of assembly, with various components such as tube plates, fins, spacer bars, etc. being brazed at a high temperature and laminated, so that the core part has a certain buckling strength There is a need to. Further, in the core portion of the plate fin type heat exchanger, the fins are repeatedly compressed or buckled and stretched due to the repetition of temperature rise and fall of the heat exchanger. For this reason, it is desirable that the corrugated fin incorporated in the low-temperature fluid flow path through which the condensing medium flows be a herringbone type that is undulated in the flow direction.
[0028]
FIG. 6 is a diagram showing the external shape and dimensional specifications of a herringbone type fin incorporated in a low-temperature fluid flow path employed in the evaporative condenser of the present invention. As shown in FIG. 6, in the design example of the evaporative condenser of the present invention, a herringbone type fin having a waviness pitch of 19.4 mm and a waviness of 2.5 mm was used. By disposing the herringbone type undulating in the flow direction of the condensing medium as reinforcing fins, it is possible to improve the heat exchange efficiency in the condensation process, and at the same time, it becomes strong against buckling and repeated loads, and during assembly production and high temperature Even at the time, there is no possibility of buckling deformation or damage.
[0029]
【The invention's effect】
According to the evaporative condenser of the present invention, even in a compression refrigerator using an ammonia refrigerant, by improving the heat exchange efficiency in the condensation process in the refrigeration cycle, the refrigeration capacity is not reduced. In addition, the size and weight of the device can be reduced. Moreover, the laminated assembly (core portion) of the plate-fin heat exchanger is not deformed or damaged even during assembling and manufacturing or repeated use for a long time.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of an ammonia compression refrigerator.
FIG. 2 is a diagram showing an entire configuration of a conventional evaporative condenser.
FIG. 3 is a diagram illustrating a configuration of a laminated assembly (core portion) in the plate fin type heat exchanger.
FIG. 4 is a diagram showing the overall configuration of the evaporative condenser of the present invention.
FIG. 5 is a diagram showing a plan configuration of a plate-fin type heat exchanger employed in the evaporative condenser of the present invention.
FIG. 6 is a view showing an external shape and a dimensional specification of a herringbone type fin incorporated in a low-temperature fluid flow path employed in the evaporative condenser of the present invention.
[Explanation of symbols]
1: compressor, 2: condenser 2a: receiver, 3: evaporator 4: expansion valve, 5: refrigerant pipe 6: casing, 6a: air inlet 6b: air outlet, 7: heat transfer element 7
8: water spray nozzle, 9: eliminator 10: blower, 11: water tank 12: cooling water pump, 13: water pipe 20: plate fin type heat exchanger 20a: refrigerant inlet, 20b: refrigerant outlet 21: tube plate, 22: Fin 23: spacer bar, 24: high-temperature fluid flow path for refrigerant 25: low-temperature fluid flow path for condensing medium 26: side plate

Claims (3)

A compressor having a compressor, a condenser, and an evaporator, which is used in a compression refrigerator using ammonia as a refrigerant, as a means for condensing the ammonia refrigerant supplied from the compressor, a means for spraying cooling water, and a means for spraying air. A means for distributing is provided, and a plate fin type heat exchanger is provided in which a flow path through which the ammonia refrigerant flows and a flow path through which a condensing medium composed of the cooling water and air flows are stacked and assembled. Evaporative condenser. The evaporative condenser according to claim 1, wherein the flow of the ammonia refrigerant and the condensing medium in the plate fin heat exchanger is performed in a cross-flow type. The evaporative condenser according to claim 1 or 2, wherein the corrugated fin incorporated in the flow path through which the condensing medium flows is a herringbone type.

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