Chilling unit

Abstract

This chilling unit is disposed outdoors. This chilling unit comprises: a refrigerant circuit that is disposed so as to straddle a machine chamber unit and a blowing chamber unit which is disposed above the machine chamber unit; a cooling fan that is disposed in the machine chamber unit; a propeller fan that is disposed in the blowing chamber unit; and a control device that is disposed in the machine chamber unit. An upper part of the machine chamber unit is in communication with a lower part of the blowing chamber unit. An upper part of the blowing chamber unit is in communication with the outside of the chilling unit. The control device determines whether or not a refrigerant in the refrigerant circuit is leaking and, when having determined that the refrigerant is leaking, operates both the cooling fan and the propeller fan.

Description

Chilling Unit

[0001] The present disclosure relates to chilling units that produce cold or hot water.

[0002] For example, International Publication No. 2021 / 024409 (Patent Document 1) discloses a chilling unit that produces cold or hot water. This chilling unit is located outdoors and has a machine room that is rectangular in plan view and an air blower room located above the machine room. The chilling unit also includes a refrigerant circuit that spans the machine room and the air blower room, an exhaust fan that is located in the air blower room and exhausts air from the air blower room to the outside, and a cooling fan that is located in the machine room and cools electrical components located within the machine room.

[0003] International Publication No. 2021 / 024409

[0004] In industries that handle refrigeration cycle equipment such as chilling units, a transition to the R290 refrigerant, which has a relatively low global warming potential (GWP), is underway to comply with recent F-gas and PFAS regulations. However, because R290 refrigerant is flammable, careful attention must be paid to preventing refrigerant leakage. In particular, for chilling units installed outdoors, it is desirable to prevent refrigerant from accumulating inside the chilling unit.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to prevent leaked refrigerant from accumulating inside a chilling unit placed outdoors.

[0006] The chilling unit according to the present disclosure is a chilling unit arranged outdoors and includes a refrigerant circuit arranged across a machine room and an air blower chamber arranged above the machine room, a first fan arranged in the machine room, a second fan arranged in the air blower chamber, and a control device arranged in the machine room. The upper part of the machine room is connected to the lower part of the air blower chamber. The upper part of the air blower chamber is connected to the outside of the chilling unit. The control device determines whether refrigerant is leaking from the refrigerant circuit and operates both the first fan and the second fan if it determines that refrigerant is leaking.

[0007] According to the present disclosure, in a chilling unit placed outdoors, it is possible to prevent leaked refrigerant from accumulating inside the unit.

[0008] FIG. 1 is an external perspective view of a chilling unit; FIG. 2 is a diagram schematically showing an example of the internal configuration of a chilling unit; FIG. 3 is a diagram showing a plan view of the inside of a machine room unit from the Z-axis direction; FIG. 4 is a flowchart showing an example of a processing procedure of a control device; and FIG. 5 is a diagram showing an image of the air flow inside the chilling unit when the cooling fan and propeller fan are operated.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and description thereof will not be repeated.

[0010] 1 is an external perspective view of a chilling unit 1 according to this embodiment. Chilling unit 1 is placed outdoors. Chilling unit 1 is used as a heat source device that supplies cold or hot water to a user-side device (user-side device 200 shown in FIG. 2 , which will be described later) placed indoors, by cooling or heating water circulated between the chilling unit 1 and the user-side device.

[0011] The chilling unit 1 comprises a machine room unit 2 and an air blower unit 3. The machine room unit 2 is installed on a horizontal installation surface such as the roof of a building. The air blower unit 3 is disposed above the machine room unit 2.

[0012] The machine chamber unit 2 has its sides and bottom covered by a hollow housing 2a, and the blower chamber unit 3 has its sides and top covered by a hollow housing 3a.

[0013] The upper part of the machine room unit 2 and the lower part of the air blower chamber unit 3 are separated by a plate-shaped drain pan 4. The drain pan 4 is provided with openings (not shown) for piping and heat exhaust. Therefore, the upper part of the machine room unit 2 is in communication with the lower part of the air blower chamber unit 3 via the openings provided in the drain pan 4.

[0014] An exhaust port 3b is provided on the top surface of the air blower chamber unit 3. Therefore, the upper part of the machine room unit 2 is in communication with the outside of the chilling unit 1 via the exhaust port 3b. A propeller fan 22 is disposed near the exhaust port 3b. When the propeller fan 22 is driven, air inside the air blower chamber unit 3 is exhausted to the outside of the chilling unit 1 through the exhaust port 3b, and air inside the machine room unit 2 also moves through the opening of the drain pan 4 to the air blower chamber unit 3 and is exhausted to the outside of the chilling unit 1 through the exhaust port 3b.

[0015] 1 shows an example in which four propeller fans 22 are arranged in a row along the horizontal direction. The interior of the housing 3a of the blower chamber unit 3 is divided by a partition wall 3c located at the center of the arrangement direction of the four propeller fans 22.

[0016] In the following, the arrangement direction of the propeller fans 22 may be referred to as the "X-axis direction," the placement direction of the blower chamber unit 3 relative to the machine chamber unit 2 (the vertical direction when the chilling unit 1 is installed on the installation surface) may be referred to as the "Z-axis direction," and the direction perpendicular to the X-axis direction and the Z-axis direction may be referred to as the "Y-axis direction."

[0017] 2 is a diagram showing a schematic diagram of an example of the internal configuration of the chilling unit 1. The chilling unit 1 is used as a heat source device that supplies cold water or hot water to the user-side device 200 by cooling or heating water circulated between the chilling unit 1 and the user-side device 200 through water piping 210. It is assumed that the user-side device 200 is placed indoors.

[0018] The chilling unit 1 is provided with multiple (four in FIG. 2 ) refrigerant circuits 10. The multiple refrigerant circuits 10 are configured so that refrigerant circulates independently of one another. The refrigerant filling each refrigerant circuit 10 circulates within the chilling unit 1, which is located outdoors. Even if a leak occurs, it is not expected to be directly released into the room where the user-side device 200 is located. For this reason, a refrigerant with a high coefficient of performance (COP) and a relatively low global warming potential (GWP) is used to fill each refrigerant circuit 10. For example, propane or a mixed refrigerant containing propane (e.g., R290 refrigerant) is used as the refrigerant filling each refrigerant circuit 10. The following description mainly focuses on the case where the refrigerant circuit 10 is filled with R290 refrigerant. Note that the refrigerant filling each refrigerant circuit 10 may be a refrigerant other than R290.

[0019] Each refrigerant circuit 10 includes an air heat exchanger 11, an expansion valve 12, a water heat exchanger 13, a compressor 14, and a four-way valve 15, and is configured such that operation of the compressor 14 causes the refrigerant to circulate through the air heat exchanger 11, the expansion valve 12, the water heat exchanger 13, the compressor 14, and the four-way valve 15. In the example shown in Figure 2, one water heat exchanger 13 is shared by two refrigerant circuits 10, so two water heat exchangers 13 are provided for four refrigerant circuits 10.

[0020] The four-way valve 15 is configured to be switchable between a first state (chilled water supply state) in which the refrigerant is circulated through the compressor 14, the air heat exchanger 11, the expansion valve 12, and the water heat exchanger 13 in this order to supply chilled water to the user-side device 200, and a second state (hot water supply state) in which the refrigerant is circulated through the compressor 14, the water heat exchanger 13, the expansion valve 12, and the air heat exchanger 11 in this order to supply hot water to the user-side device 200. Figure 1 illustrates an example of a state in which the four-way valve 15 is controlled to the first state (chilled water supply state).

[0021] Each refrigerant circuit 10 is disposed across the machine room unit 2 and the blower room unit 3 shown in Fig. 1. Specifically, in each refrigerant circuit 10, the air heat exchanger 11 is disposed in the blower room unit 3, and the expansion valve 12, the water heat exchanger 13, the compressor 14, and the four-way valve 15 are disposed in the machine room unit 2.

[0022] Each refrigerant circuit 10 is further provided with a propeller fan (second blower) 22. The propeller fan 22 is disposed above the air heat exchanger 11 in the blower chamber unit 3 shown in FIG. 1 and is configured to exhaust air from the blower chamber unit 3 to the outside of the chilling unit 1 when activated. In this embodiment, the rotation speed of the propeller fan 22 is switchable between a first rotation speed on the low side and a second rotation speed on the high side.

[0023] The chilling unit 1 further includes a control box 100, a leakage sensor 120, and a cooling fan (first blower) 21. The control box 100, the leakage sensor 120, and the cooling fan 21 are disposed in the machine room unit 2 shown in FIG.

[0024] The cooling fan 21 is disposed near the control box 100 inside the machine room unit 2, and is configured to blow air toward the control box 100 when activated. The cooling fan 21 is disposed below the center of the machine room unit 2 in the Z-axis direction (the vertical direction when the chilling unit 1 is installed).

[0025] 3 is a plan view of the interior of the machine room unit 2 as viewed from the Z-axis direction. Arranged inside the machine room unit 2 are the expansion valves 12 of the four refrigerant circuits 10, the water heat exchangers 13, the compressors 14, the control boxes 100, and the cooling fans 21. The control box 100 is divided into two halves, and the cooling fans 21 are arranged near each of the two control boxes 100.

[0026] The control box 100 is cooled by the air blown by the cooling fan 21. Furthermore, the air blown by the cooling fan 21 diffuses the air inside the machine room unit 2, which also promotes heat dissipation from heat-generating components such as the compressor 14 arranged inside the machine room unit 2.

[0027] 2, the leakage sensor 120 is a sensor for detecting refrigerant leakage in the refrigerant circuit 10. The leakage sensor 120 is disposed below the center in the Z-axis direction (vertical direction) of the machine room unit 2. When the leakage sensor 120 detects refrigerant in the refrigerant circuit 10, it transmits a signal indicating refrigerant leakage to the control device 110, which will be described later.

[0028] The control box 100 houses electrical components for control, such as a control device 110 that controls each device in the chilling unit 1 (such as the compressor 14, expansion valve 12, four-way valve 15, cooling fan 21, and propeller fan 22), drivers for each device, multiple power modules such as inverters and converters, multiple smoothing capacitors, and multiple reactors for power factor correction.

[0029] The control device 110 is configured to include a central processing unit, memory devices (read only memory (ROM) and random access memory (RAM)), input / output buffers, etc. (none of which are shown). The control device 110 controls each device in the chilling unit 1 according to programs stored in the memory devices. This control is not limited to software processing, but can also be performed by dedicated hardware (electronic circuits).

[0030] When the chilling unit 1 is put into cooling operation, the control device 110 activates the compressors 14 of the refrigerant circuits 10 and sets the four-way valves 15 to the first state (chilled water supply state). This causes chilled water to be supplied from the chilling unit 1 to the user-side device 200.

[0031] When the chilling unit 1 is put into heating operation, the control device 110 activates the compressors 14 of the refrigerant circuits 10 and sets the four-way valve 15 to the second state (hot water supply state). This causes hot water to be supplied from the chilling unit 1 to the user-side device 200.

[0032] Furthermore, the control device 110 operates the cooling fan 21 and the propeller fan 22 as needed while the chilling unit 1 is in operation. This cools heat-generating components such as the control box 100 and the compressor 14 in the machine room unit 2 and promotes heat exchange in the air heat exchanger 11 in the blower room unit 3. The air that has absorbed heat inside the chilling unit 1 is diffused inside the chilling unit 1 and discharged to the outside of the chilling unit 1 through the exhaust port 3b.

[0033] [Control in the Event of Refrigerant Leakage] In the chilling unit 1 configured as described above, if flammable R290 refrigerant leaks from the refrigerant circuit 10, it is desirable to prevent the leaked refrigerant from accumulating inside the chilling unit 1. In the chilling unit 1, the refrigerant circuit 10 is arranged across the machine room unit 2 and the air blower room unit 3, so it is expected that refrigerant leakage will occur either in the machine room unit 2 or in the air blower room unit 3. In either case, because the specific gravity of R290 refrigerant is greater than that of air, it is expected that the leaked refrigerant will move to the bottom of the machine room unit 2.

[0034] Therefore, when a refrigerant leak is detected by the leak sensor 120 located at the bottom of the machine room unit 2, the control device 110 of this embodiment activates the propeller fan 22 and cooling fan 21 inside the chilling unit 1 to diffuse and discharge the leaked refrigerant to the outside of the chilling unit 1. This prevents the leaked refrigerant from accumulating inside the chilling unit 1.

[0035] 4 is a flowchart showing an example of a processing procedure executed by the control device 110. This flowchart is repeatedly executed every time a predetermined condition is met (for example, at every predetermined cycle).

[0036] The control device 110 determines whether or not refrigerant is leaking into the chilling unit 1 based on the output of the leakage sensor 120 (step S10). If it is determined that refrigerant is not leaking (NO in step S10), the control device 110 skips the subsequent processing and ends the processing.

[0037] If it is determined that refrigerant is leaking (YES in step S10), the control device 110 stops operation of all compressors 14 in the chilling unit 1 to prevent the refrigerant leakage from expanding (step S12).

[0038] Next, the control device 110 activates all of the cooling fans 21 and propeller fans 22 in the chilling unit 1 (step S14). Specifically, the control device 110 continues the operation of the cooling fans 21 and propeller fans 22 that are already in operation, and activates the cooling fans 21 and propeller fans 22 that are stopped.

[0039] Next, the control device 110 determines whether any propeller fan 22 is rotating at a low speed (step S16). This determination is a process for confirming whether any propeller fan 22 is capable of increasing its rotation speed. If no propeller fan 22 is rotating at a low speed (NO in step S16), that is, if all four propeller fans 22 are already rotating at high speed, the control device 110 determines that no propeller fan 22 is capable of increasing its speed, skips the subsequent process, and ends the process.

[0040] If there is a propeller fan 22 rotating at a low speed (YES in step S16), the control device 110 increases the rotation speed of the propeller fan 22 to a second rotation speed (step S18), thereby allowing the leaked refrigerant to be discharged to the outside of the chilling unit 1 more quickly.

[0041] Figure 5 is a diagram showing an image of the air flow inside the chilling unit 1 when the cooling fan 21 and the propeller fan 22 are operated. Note that Figure 5 shows the case where only the cooling fan 21 inside the machine room unit 2 and one propeller fan 22 (the second from the right in Figure 5) inside the air blower room unit 3 are operated.

[0042] 5, by operating the cooling fan 21 and the propeller fan 22, the air inside the chilling unit 1 is diffused and discharged. Any refrigerant leaking inside the chilling unit 1 is carried by this air flow and discharged to the outside of the chilling unit 1.

[0043] As described above, when a refrigerant leak is detected based on the leak sensor 120 located below the machine room unit 2, the control device 110 according to this embodiment activates the cooling fan 21 and propeller fan 22 inside the chilling unit 1. This causes the leaked refrigerant to be diffused within the chilling unit 1 and then discharged to the outside of the chilling unit 1. This prevents the leaked refrigerant from accumulating inside the chilling unit 1.

[0044] Furthermore, when a refrigerant leak is detected, the control device 110 according to this embodiment activates the cooling fan 21 and the propeller fan 22 and stops the compressor 14. This makes it possible to prevent the refrigerant leak from expanding.

[0045] Furthermore, when a refrigerant leak is detected and the propeller fan 22 is rotating at a first rotation speed on the low side, the control device 110 according to this embodiment increases the rotation speed of the propeller fan 22 to a second rotation speed on the high side, thereby allowing the leaked refrigerant to be discharged to the outside of the chilling unit 1 more quickly.

[0046] Furthermore, the cooling fan 21 in this embodiment is positioned below the center in the Z-axis direction (the vertical direction when the chilling unit 1 is installed) of the machine room unit 2. Therefore, by operating the cooling fan 21, it is possible to effectively prevent the R290 refrigerant, which has a higher specific gravity than air, from stagnating in the lower part of the machine room unit 2.

[0047] Furthermore, the leak sensor 120 according to this embodiment is positioned below the center in the Z-axis direction (the vertical direction when the chilling unit 1 is installed) of the machine room unit 2. This allows the leak sensor 120 to accurately detect R290 refrigerant, which has a higher specific gravity than air.

[0048] [Modification 1] In step S10 of the flowchart in FIG. 4 described above, the presence or absence of refrigerant leakage is determined based on the output of the leakage sensor 120. However, the presence or absence of refrigerant leakage may be determined without using the leakage sensor 120.

[0049] For example, during cooling operation of the chilling unit 1, it may be determined that a refrigerant leak has occurred if the degree of subcooling SC of the refrigerant near the outlet of the air heat exchanger 11 is equal to or less than the threshold value th1 for determining a refrigerant leak. Note that because the degree of subcooling SC varies depending on the operating state, the threshold value th1 may be determined by machine learning.

[0050] Furthermore, during heating operation of the chilling unit 1, if the expansion valve 12 is fully open and the difference between the intake superheat SHs of the compressor 14 and the target intake superheat SHm (=SHs-SHm) is equal to or greater than the threshold value th2 for determining whether or not a refrigerant leaks, it may be determined that a refrigerant leak has occurred.

[0051] Furthermore, when the chilling unit 1 is stopped, it may be determined that refrigerant is leaking if the pressure on the outlet side (high pressure side) of the compressor 14 is equal to or lower than the threshold value P1 for determining whether refrigerant is leaking.

[0052] [Variation 2] In the above embodiment, an example in which four refrigerant circuits 10 are provided within the chilling unit 1 has been described, but the number of refrigerant circuits 10 provided within the chilling unit 1 is not limited to four, and may be four or more, or may be one.

[0053] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0054] 1 Chilling unit, 2 Machine room unit, 2a, 3a Housing, 3 Blower room unit, 3b Exhaust port, 3c Partition wall, 4 Drain pan, 10 Refrigerant circuit, 11 Air heat exchanger, 12 Expansion valve, 13 Water heat exchanger, 14 Compressor, 15 Four-way valve, 21 Cooling fan, 22 Propeller fan, 100 Control box, 110 Control device, 120 Leak sensor, 200 User side device, 210 Water piping.

Claims

1. A chilling unit arranged outdoors, comprising a refrigerant circuit arranged across a machine room and a blower room arranged above the machine room, a first blower arranged in the machine room, a second blower arranged in the blower room, and a control device arranged in the machine room. The upper part of the machine room communicates with the lower part of the blower room, and the upper part of the blower room communicates with the outside of the chilling unit. The control device determines whether the refrigerant in the refrigerant circuit is leaking, and operates both the first blower and the second blower when it is determined that the refrigerant is leaking.

2. The refrigerant circuit includes an air heat exchanger arranged in the blower room, an expansion valve, a water heat exchanger, and a compressor arranged in the machine room. The operation of the compressor is configured to circulate the refrigerant through the air heat exchanger, the expansion valve, the water heat exchanger, and the compressor. When it is determined that the refrigerant is leaking, the control device operates both the first blower and the second blower and stops the compressor. The chilling unit according to claim 1.

3. The first blower is arranged near the control device in the machine room and blows air to the control device when operating. The second blower is arranged above the air heat exchanger in the blower room and discharges the air in the blower room from the upper part of the blower room to the outside of the blower room when operating. The chilling unit according to claim 2.

4. The refrigerant contains propane, and the first blower is arranged below the vertical center of the machine room. The chilling unit according to claim 1.

5. Further comprising a sensor arranged below the vertical center of the machine room for detecting refrigerant leakage, and the control device determines whether the refrigerant is leaking based on the output of the sensor. The chilling unit according to claim 1.

6. The chiller unit according to claim 1, wherein when it is determined that the refrigerant in the refrigerant circuit is leaking and the second blower is rotating at the first rotational speed, the control device increases the rotational speed of the second blower to be higher than the first rotational speed.

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