JP5971907B2 - Air conditioner using direct expansion coil - Google Patents

Description

  The present invention relates to an air conditioner that uses a plurality of directly expanded coils, and more particularly to an air conditioner that uses a series of two directly expanded coils as a plurality of parallel expanded coils.

Conventionally, the heat medium of an air conditioner using a water coil is cold water, hot water, steam, or the like, but the heat medium of the refrigerant coil of the air conditioner of a direct expansion coil is a refrigerant other than water.
Conventionally, strict air conditioning management is required in clean rooms, but normally, the allowable range of set temperature and humidity is controlled within ± 3 ° C. for temperature and within 10% for humidity.
By the way, the heat medium of the air conditioner using a water coil is cold water, hot water, steam, etc., and the heat medium of the refrigerant coil of the air conditioner of the direct expansion coil is a refrigerant, but as described below, There are advantages and disadvantages.

The basic air conditioning system using a water coil in a clean room is as shown in FIG. 1, but the air OA from the outside is heat-exchanged by controlling the cold water coil a with a valve i, and the target is roughly Air supply SA obtained by cooling (heating) below the temperature and humidity and finely adjusting by the reheating coil b and the humidifier c is obtained.
The air state change in this case will be described with reference to the air diagram of FIG. 2. When the outside air OA is in the state of point A in FIG. 2, the water coil a is connected to the refrigerator h or Cold water (hot water, steam) is supplied from the chiller, and by controlling the valve d, the dew point temperature where the coil outlet air temperature is set, in fact, the dew point temperature setting value is lower than the target absolute humidity with a margin The temperature is lowered to (until the target absolute humidity line in FIG. 2) and the process moves to point B.
Thereafter, hot water or steam at a high temperature is controlled by the valve f by the boiler e and supplied to the reheating coil b, reheated from the dew point temperature to a humidifiable temperature, and the air temperature is raised to the point C in FIG. Further, the steam from the boiler e is sprayed from the humidifier c to reach the final target humidity, which is raised to the point D in FIG.

  However, the basic air conditioning system using a conventional water coil as shown in FIG. 1 requires (1) a heat source machine room for installing a heat source device for cooling and reheating, and (2) When considering backup, another system must be installed. (3) Regardless of the number of distributed air conditioners, large heat source equipment operates and it is difficult to reduce the chilled water transport power. 4) There is a problem that the heat source equipment, cold water, reheat coil, and humidification valve control are in different construction categories, and the management items after construction become complicated.

In addition, since the direct expansion coil has no indirect heat transfer, the heating and cooling efficiency of the direct expansion coil system should exceed the water coil. However, since the direct expansion coil is a refrigerant other than water, There is a problem that it is difficult to control pressure and temperature for different phases such as gas and gas, and it is difficult to manage fine control.
For example, the basic air conditioning system using a direct expansion coil in a clean room is as shown in FIG. 3, but the use of the water coil a in FIG. The directly expanded coils g1, g2, and g3 are arranged in parallel. It is difficult to control a wide range of air conditioning with a direct expansion coil. Therefore, three units of the direct expansion coil are arranged in parallel, one unit is operated when the load is low, and all units are operated when the load is high. Is possible.

The air state change in this case will be described with reference to the air diagram of FIG. 2 and the system of FIG. 3 will be described. When the outside air OA is in the state of point A in FIG. Operate all units k1, k2, and k3, set the coil outlet air temperature of the direct expansion coils g1, g2, and g3 below the set dew point temperature, and set the dew point temperature to a dew point temperature lower than the target absolute humidity with a margin, Move to point B.
After that, as with the water coil air conditioner, hot water or steam is controlled by the valve e by the boiler e, supplied to the reheating coil b, reheated from the dew point temperature to the humidifiable temperature, and the air temperature is shown in FIG. To C point. Further, the steam from the boiler e is sprayed from the humidifier c to reach the final target humidity, which is raised to the point D in FIG.

However, the basic air conditioning system using a direct expansion coil as shown in FIG. 3 is: (1) Since the direct expansion coil is installed in parallel, it is difficult to stop the outdoor unit due to the load, considering the dehumidification capacity. Cannot handle during operation, maintenance or failure. For example, referring to the air diagram of FIG. 4, when the direct expansion coils g2 and g3 are stopped and in a bypass state, and only the direct expansion coil g1 is operating, the outlet air temperature of the direct expansion coil g1 is B. However, since the directly expanded coils g2 and g3 are in the bypass state, the air in which these coils are mixed becomes the Bmix point and does not fall below the set dew point temperature. Therefore, it is necessary to always operate all of them.
Further, (2) since the direct expansion coil outlet temperature is set to be equal to or lower than the target dew point temperature, all outdoor units are always required to operate, and the coil outlet air temperature is considerably lower than the target value at low load. Therefore, since the reheating capability of B → C and the humidification capability of C → D are increased, as a result, energy saving operation is not performed.

  For this reason, the direct expansion coil has a small air conditioner for each room that uses one outdoor unit for each indoor unit such as a home air conditioner that does not require strict control of air temperature and humidity. However, air conditioning equipment with only a direct expansion coil tends to be difficult to be adopted in large factories, etc., and as disclosed in Patent Documents 1 and 2, An air conditioning system has been proposed that can be used in large factories and the like by using it together.

JP 2006-292300 A JP 2008-75978 A

  The present invention has been made in view of the above-mentioned problems, and as an air conditioner using only a direct expansion coil, a heat source device for generating cold water for the water coil is unnecessary, and space saving is possible, enabling rotation operation. As a result, it can easily handle backup operation at the time of failure, and can control temperature and humidity over a wide range in the same way as conventional cold water coils and parallel arrangements. It is intended to provide an air conditioner that can be installed with a humidifier and satisfy constant temperature and humidity conditions.

In order to solve the above-mentioned problem, the invention of claim 1 arranges a first direct expansion coil group that introduces outside air and cools or heats it with a refrigerant, and arranges a second direct expansion coil group downstream thereof,
A plurality of first direct expansion coil groups arranged in parallel; a plurality of the second direct expansion coil groups arranged in parallel;
The plurality of direct expansion coils of the first direct expansion coil group and the plurality of direct expansion coils of the second direct expansion coil group can be independently controlled,
When a part of the direct expansion coils of one of the first direct expansion coil group or the second direct expansion coil group fails, all the direct expansion coils of the other non-failing coil group are operated. Is an air conditioner using a direct expansion coil characterized by
According to a second aspect of the present invention, in the air conditioner using the direct expansion coil according to the first aspect, a reheating coil and a humidifier are disposed downstream of the second direct expansion coil group .
The invention of claim 3 is an air conditioner using the direct expansion coil according to claim 1 or 2, wherein the first direct expansion coil group includes two direct expansion coils arranged in parallel. .
A fourth aspect of the present invention is the air conditioner using the direct expansion coil according to the first, second, or third aspect, wherein the second direct expansion coil group includes four direct expansion coils arranged in parallel. And

According to the air conditioner using the direct expansion coil of the present invention, unlike a conventional air coil using an air coil, there is no need for cooling with cold water, so there is no need for a heat source device for producing cold water. Only a space for installing the machine, and a machine room for a cold heat source is unnecessary.
Also, by rotating the direct expansion coil group arranged in parallel and the direct expansion coil group arranged in parallel in two stages in series, the rotation operation can be performed and the operation of one part of the direct expansion coil group or the outdoor unit can be stopped. This makes it possible to extend the life of the apparatus, and can easily handle backup operation when some of the directly expanded coils fail.
Moreover, instead of the conventional chilled water coil and the parallel expansion coil, a plurality of parallel expansion coils are arranged in series in two stages to control the supply air dew point temperature, so that the upstream direct expansion coils After performing rough cooling control, the temperature and humidity can be finely controlled in the downstream direct expansion coil group, and a wide range of temperature and humidity management is possible. It can be controlled to satisfy the same manner established the reheat coil humidifier accurately constant temperature and humidity conditions that Do.
In particular, according to the air conditioner using a direct expansion coil of claim 1, as described in FIG. 3, when there is a direct expansion coil of the bypass state, these dew point temperature below that mixed air is set However, if some of the direct expansion coils of one of the first direct expansion coil group or the second direct expansion coil group fail, the direct current of the other coil group that has not failed Since all of the expansion coils are operated, there is no direct expansion coil that is in a bypass state in the process from the outside air to the supply air, and the dew point temperature can be kept below the set dehumidification temperature.

Configuration schematic diagram of conventional air conditioning system using water coil, FIG. 1 and FIG. 3 are air line diagrams for explaining changes in the state of conventional air, Configuration schematic diagram of an air conditioning system in which three conventional direct expansion coils are arranged in parallel, FIG. 3 is an air diagram illustrating problems in the air conditioner of FIG. Schematic of an air conditioner using the directly expanded coil group of Example 1 of the present invention, An air diagram illustrating the state of the outside air OA and the operating state of each direct expansion coil in Example 1, The figure of the graph of the measurement result of the driving | running state corresponding to the change of the state of the external air OA of Example 1, Explanatory drawing explaining the example of a combination of rotation and backup operation in Example 1. It is the schematic of the air conditioner using the direct expansion coil group of Example 2 of this invention.

A preferred embodiment of an air conditioner using a direct expansion coil of the present invention will be described with reference to the drawings.
[Example 1]
FIG. 5 is an overall system diagram of the air conditioner 1 for a clean room using the direct expansion coil according to the first embodiment. The outside air OA (from the right side in FIG. 5) is introduced, and is first cooled by the refrigerant on the upstream side. The first direct expansion coil group 2 is disposed, the second direct expansion coil group 3 is disposed downstream, and the reheating coil 4 and the humidifier 5 are disposed downstream thereof. In addition, although the air conditioner 1 of a present Example is used for a clean room, since a heating apparatus etc. usually exist in a room and raises indoor temperature, it demonstrates by the case where a cooling function is used. In the present invention, “outside air” does not mean only outdoor air, but air that takes in air conditioning from outside the target air conditioner.
The first direct expansion coil group 2 includes two direct expansion coils 21 and 22 that are two direct expansion coils arranged in parallel with each other in air flow. Are connected to the outdoor unit 23 including the compressor 231 and the fan 232 through control valves 211 and 221, respectively, and are controlled independently.

The second direct expansion coil group 3 is disposed downstream of the first direct expansion coil 2. The direct expansion coil group 3 includes four direct expansion coils 31 to 34, each of which has an air flow. The two direct expansion coils 31 and 32 are connected to the outdoor unit 35 including the compressor 351 and the fan 352 through the control valves 311 and 321 respectively, and are independent of each other. To be controlled. Similarly, the other two direct expansion coils 33 and 34 are connected to an outdoor unit 36 including a compressor 361 and a fan 362 via control valves 331 and 341, respectively, and are controlled independently.
A reheating coil 4 and a humidifier 5 are provided downstream of the second direct expansion coil group 3 in order to finely adjust the air conditioning state to a target temperature / humidity. Then, hot water or steam is produced and supplied to the reheating coil 4 via the control valve (valve) 41 to heat the supply air SA, and the steam is supplied to the humidifier 5 via the control valve (valve) 51. The supply air SA is humidified by spraying from the nozzle.

Here, experimental results in the above-described configuration in the first embodiment will be described.
Example of operation experiment Design air volume: 5000m ³ / h (Outside air intake: 20%)
Air supply target: 12.6 ℃
Coil combination: In series ... 2 rows Number of stages ... (windward) 1 outdoor unit, 2 stages
(Downward) 2 outdoor units, 4 stages In general, the direct expansion coil has a theoretical efficiency that increases as the temperature difference between the high temperature source and the low temperature source decreases, and the rated operation is efficient.

Considering the six directly expanded coils 21, 22, 31, 32, 33, and 34 of the present embodiment, as shown in the air diagram of FIG. In order to achieve the target temperature and humidity, the load becomes high and the entire direct expansion coil is operated.
Next, when the outside air OA is in the B region where the humidity is slightly lower than the high-temperature and high-humidity A region, the load is slightly reduced, so one of the six units can be rested. The expansion coil 34 can be stopped.
Further, when the outside air OA is in the C region where the humidity is lower than that in the B region, the load is further reduced, so that any two of the six units can be rested. In this embodiment, the direct expansion coils 34 and 33 are used. Can be stopped.

Similarly, when the outside air OA is in the D region where the humidity and temperature are lower than those in the C region, the load is further reduced. Therefore, any three of the six units can rest, and in this embodiment, the direct expansion coil 34, 33, 32 can be stopped.
Similarly, when the outside air OA is in the E region where the humidity and temperature are lower than those in the D region, the load is also small, so that any four of the six units can be rested. The direct expansion coils 31 to 34 of the expansion coil group 3 are stopped, and only the first direct expansion coil group 2 is operated to realize energy saving.

Referring to FIG. 7 which graphs the measurement result of the actual operation state in Example 1 at this time, FIG. 7 shows a case where the inlet air condition (decreasing enthalpy) in the air conditioner 1 is changed. It is the graph which measured the temperature and humidity at the exit of the.
First, humidity will be described. The upper side (thin line) in FIG. 7 is a graph relating to the change in humidity. The inlet humidity to the air conditioner 1 is about 90 to 80%, and the state of the outside air (inlet) OA is Even if the A-to-E region is changed, the direct expansion coil groups 1 and 2 are switched to the corresponding operating state, and the number of directly-expanded coil operating units is gradually reduced corresponding to the A to E region. It can be seen that the outlet humidity: W is maintained at 50 to 60%.

Next, the temperature will be described. The lower side of FIG. 7 is a graph relating to the temperature change, but the inlet temperature of the air conditioner 1: Y decreases from 33 ° C. to about 18 and the state of the outside air (inlet) OA is A. Even if the operating state of the direct expansion coil is changed and the number of operating units of the direct expansion coil is gradually reduced, the operation of the direct expansion coil is newly stopped by switching the region on the way. However, the outlet temperature: Z is still in the range of 10.3-12.6 ° C.
In this way, a part of the direct expansion coil can be stopped outside the high-temperature and high-humidity A region, and if the low tension is assembled, the direct expansion coil and the outdoor unit can be efficiently rested. Rotation operation can be performed to extend the service life of directly expanded coils and outdoor units.

In addition, according to the present embodiment, the backup operation at the time of failure can be easily handled. This will be described along with FIG. 8 together with an example of rotation.
In FIG. 8, six direct expansion coils are operated in the high temperature and high humidity A region, but in the C region where the load is reduced, each direct expansion coil 21, 22, 31, 32, 33, 34 is Since it can be controlled independently, the two directly expanded coils and the outdoor unit associated with them can be rested. In this case, since each direct expansion coil 21, 22, 31, 32, 33, 34 can be controlled independently, the selection of two units is optional when the capacity is the same. The direct expansion coils 31 and 32 can be rested as described above, and the direct expansion coils 33 and 34 and the outdoor units associated with them can be rested as in the C region operation 2, so that the next C region operation can be performed. 1 and 2 may be operated alternately.

In the normal operation, as shown at both ends of the middle stage in FIG. 8, the linear expansion coils 21 and 22 are operated in the E region and the four linear expansion coils 31 to 34 are stopped. However, as shown in the lower ends (a) and (f) of FIG. 8, when the directly expanded coils 21 and 22 have to be stopped due to failure or maintenance, four directly expanded coils 31 to 34 are connected. If it is operated, the normal cooling capacity can be secured.
Similarly, when the direct expansion coils 31 and 32 are rested as in region C operation 1 of FIG. 8, as shown in the lower part of FIG. If it must be stopped, the normal cooling capacity can be secured by operating the four units of the direct expansion coils 31 and 32 and the direct expansion coils 21 and 22, and the lower ( As shown in c), when the direct expansion coils 21 and 22 have to be stopped due to failure or maintenance, the normal cooling capacity can be secured by operating four of the direct expansion coils 31 to 34. .

  Further, when the direct expansion coils 33 and 34 are rested as in the C region operation 2 of FIG. 8, the direct expansion coils 31 and 32 are stopped due to failure or maintenance as shown in (d) of the lower part of FIG. If this is unavoidable, the normal cooling capacity can be secured by operating the four units of the direct expansion coils 33 and 34 and the direct expansion coils 21 and 22, and (e As shown in (4), if the direct expansion coils 21 and 22 have to be stopped due to failure or maintenance, the normal cooling capacity can be ensured by operating four of the direct expansion coils 31 to 34.

[Example 2]
Next, Example 2 will be described. As shown in FIG. 9, the difference between the second embodiment and the first embodiment is that the configuration of the second directly expanded coil group 3 is configured by arranging two directly expanded coils 37 and 38 in parallel. Since it is the same as Example 1, description is abbreviate | omitted.
The air conditioner using the direct expansion coil according to the second embodiment requires only four direct expansion coils, and the associated outdoor units 23, 39 and the like (compressors 231, 391, fans 232, 392) can be reduced, and the entire space is reduced. In spite of the simple structure, the operation and effect are basically obtained in the same manner as in the first embodiment, and one part of the direct expansion coil is stopped except in the high load region of high temperature and high humidity. If the direct expansion coil and the outdoor unit are efficiently rested and the rotation operation is performed systematically, it is possible to extend the life of the direct expansion coil and the outdoor unit. Therefore, since the number of components is small and the space is saved, it is optimal for a small-scale clean room air conditioner.

  As described in detail above, according to the first and second embodiments, (1) since a group of multi-stage (two-stage) parallel direct expansion coils is further arranged, the direct expansion coil outlet temperature is set by fine step number control. The dew point temperature can be controlled. In particular, in the first embodiment, since the second direct expansion coil group is arranged in four stages, accurate temperature / humidity control can be performed at a position close to the supply air. In addition, (2) heat source (outdoor unit) and valve control can be packaged, management after construction is easy, and expansion / repair is easy. Furthermore, (3) a small energy efficiency is better than that of the conventional system due to fine stage number control, and the error of the air temperature at the outlet of the direct expansion coil is about ± 3 ° C., so less energy is used for reheating and humidification. Note that this apparatus is also compatible with reheating coils and heat pumps (refrigerants).

Furthermore, (4) the air conditioner using the direct expansion coil of the present embodiment, unlike the conventional air coil using air coil, does not require cooling with cold water, and therefore does not require a heat source device for producing cold water. Thus, only an outdoor unit installation space is required, and a machine room for a cold heat source for the water coil is not required. In addition, (5) Rotation operation is possible by combining the parallel expansion coil group and the parallel expansion coil group in two stages in series. The service life can be extended, and backup operation when some of the direct expansion coils and outdoor units fail can be easily handled. In addition, (6) since the supply air dew point temperature control is performed by arranging a plurality of parallelly arranged direct expansion coil groups in series in two stages, after performing rough cooling control on the upstream direct expansion coil group, The temperature and humidity can be finely controlled with a group of directly expanded coils, and a wide range of temperature and humidity management is possible. In addition, a reheat coil and humidifier are installed in the lee as in the case of conventional water coils. In addition, it is possible to perform control that satisfies the constant temperature and humidity conditions.
Of course, the present invention is not limited to the above-described embodiments as long as the features of the present invention are not impaired.

a ... cold water coil, b ... reheat coil, c ... humidifier, d ... valve,
e ・ Boiler, f ・ Valve, g1, g2, g3 ・ ・ Direct expansion coil,
h ・ ・ Refrigerator, i ・ ・ Valve, k1, k2, k3 ・ ・ Outdoor unit,
1. Air conditioner,
2. First direct expansion coil group, 21, 22 ... Direct expansion coil,
211, 221 .. Control valve,
23..Outdoor unit, 231 ... Compressor, 232 ... Fan,
3. Second direct expansion coil group 31, 32, 33, 34. Direct expansion coil,
311, 321, 331, 341 .. control valve,
35,36,39 .. Outdoor unit, 351,361,391 ..Compressor,
352,362,392 ... Fan,
4. Reheat coil, 41 Control valve (valve)
5 .... Humidifier, 51 ... Control valve (valve),
6. Boiler

Claims (4)

While arranging the first direct expansion coil group that introduces outside air and cools or heats it with the refrigerant, arranges the second direct expansion coil group downstream thereof,
A plurality of first direct expansion coil groups arranged in parallel; a plurality of the second direct expansion coil groups arranged in parallel;
The plurality of direct expansion coils of the first direct expansion coil group and the plurality of direct expansion coils of the second direct expansion coil group can be independently controlled,
When a part of the direct expansion coils of one of the first direct expansion coil group or the second direct expansion coil group fails, all the direct expansion coils of the other non-failing coil group are operated. An air conditioner that uses a direct expansion coil. The air conditioner using a direct expansion coil according to claim 1, wherein a reheating coil and a humidifier are arranged downstream of the second direct expansion coil group .   The air conditioner using the directly expanded coil according to claim 1 or 2, wherein the first directly expanded coil group includes two directly expanded coils arranged in parallel.   The air conditioner using the direct expansion coil according to claim 1, wherein the second direct expansion coil group includes four direct expansion coils arranged in parallel.

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