Patent Application
20250224122
The present disclosure relates to a heat source unit and an air conditioner.
An air conditioner using carbon dioxide as a refrigerant is known. Patent Literature 1 (JP 2008-045769 A) discloses a method for filling a carbon dioxide refrigerant for the purpose of improving the efficiency of installation work of an air conditioner.
In order to further improve the efficiency of installation work of the air conditioner, a technique is known in which a heat source unit (outdoor unit) is filled with a refrigerant in advance in a manufacturing factory, and a refrigerant circuit is filled with the refrigerant by connecting the heat source unit and a utilization unit (indoor unit) at an installation site.
A heat source unit according to a first aspect is connected to a utilization unit and constitutes an air conditioner. The heat source unit includes a compressor, a heat source heat exchanger, a first shutoff valve, a second shutoff valve, a refrigerant flow path, and a refrigerant. The refrigerant flow path is a flow path in which the compressor, the heat source heat exchanger, the first shutoff valve, and the second shutoff valve are connected by a refrigerant pipe. The refrigerant flow path is filled with the refrigerant. The refrigerant includes carbon dioxide.
A filling amount V1 (kg) of the refrigerant filled in the refrigerant flow path, a volume V2 (L) of the refrigerant flow path, and a design pressure P (MPa) of the refrigerant flow path satisfy the following relationship.
V1×a≤V2≤V1×b
a=0.078×P2−2.111×P+15.771
b=0.055×P2−1.768×P+16.144
Although details will be described later, the refrigerant to be filled in the refrigerant circuit 10 is filled in the heat source unit 2 in a manufacturing factory or the like. The heat source unit 2 and the utilization unit 3 are connected to each other via the connecting pipes 6 and 7 at an installation site of the air conditioner 1 or the like, and thus, the refrigerant circuit 10 is filled with the refrigerant filled in the heat source unit 2.
The utilization unit 3 is installed in the air conditioning target space. The utilization unit 3 includes a utilization refrigerant flow path 30 constituting a part of the refrigerant circuit 10. The utilization refrigerant flow path 30 includes a utilization heat exchanger 31.
The utilization heat exchanger 31 exchanges heat between the refrigerant flowing inside and air in the air conditioning target space. The utilization heat exchanger 31 has one end connected to the first connecting pipe 6 via a refrigerant pipe 30a. The other end of the utilization heat exchanger 31 is connected to the second connecting pipe 7 via the refrigerant pipe 30a.
The heat source unit 2 is installed outside the air conditioning target space (outdoor space or the like). The heat source unit 2 includes a heat source refrigerant flow path 20 constituting a part of the refrigerant circuit 10. The heat source refrigerant flow path 20 includes a compressor 21, a flow path switching mechanism 22, a heat source heat exchanger 23, a heat source expansion mechanism 24, a first shutoff valve 25, a second shutoff valve 26, and an accumulator 27. The compressor 21, the flow path switching mechanism 22, the heat source heat exchanger 23, the heat source expansion mechanism 24, the first shutoff valve 25, the second shutoff valve 26, and the accumulator 27 are connected to each other via a refrigerant pipe 20a. The heat source refrigerant flow path 20 is an example of a refrigerant flow path.
The compressor 21 sucks a low-pressure refrigerant in a refrigeration cycle from a suction pipe 21a, compresses the refrigerant by a compression mechanism (not illustrated), and discharges the compressed refrigerant as a high-pressure refrigerant to a discharge pipe 21b. In the present embodiment, the heat source unit 2 includes only one compressor 21, but in some embodiments, the number of compressors 21 is not limited to one and may be plural. The activation, stop, and capacity control of the compressor 21 can be performed by a control unit (not illustrated). The control unit includes programmable circuitry such as a CPU (or multiple CPUs) and a memory that stores computer readable code, which when executed by the CPU(s) configures the CPU(s) to perform the control operations discussed herein.
The flow path switching mechanism 22 switches a flow direction of the refrigerant and changes a state of the refrigerant circuit 10 between a first state and a second state. When the refrigerant circuit 10 is in the first state, the heat source heat exchanger 23 functions as a radiator for the refrigerant, and the utilization heat exchanger 31 functions as an evaporator for the refrigerant. When the refrigerant circuit 10 is in the second state, the heat source heat exchanger 23 functions as an evaporator for the refrigerant, and the utilization heat exchanger 31 functions as a radiator for the refrigerant. The state of the flow path switching mechanism 22 can be changed by a control unit (not illustrated).
In the present embodiment, the flow path switching mechanism 22 is a four-way switching valve having four ports P1, P2, P3, and P4. The port P1 is connected to one end of the heat source heat exchanger 23. The port P2 is connected to the discharge pipe 21b of the compressor 21. The port P3 is connected to the accumulator 27. The port P4 is connected to the second shutoff valve 26. In the first state, the port P1 communicates with the port P2, and the port P3 communicates with the port P4. In the second state, the port P1 communicates with the port P3, and the port P2 communicates with the port P4.
The flow path switching mechanism 22 is not required to be a four-way switching valve. For example, the flow path switching mechanism 22 may be configured by combining a plurality of electromagnetic valves and refrigerant tubes so that the flow direction of the refrigerant can be switched as described above.
The heat source heat exchanger 23 causes heat exchange between a refrigerant flowing inside and air at an installation site of the heat source unit 2 (heat source air). One end of the heat source heat exchanger 23 is connected to the port P1 of the flow path switching mechanism 22. The other end of the heat source heat exchanger 23 is connected to the heat source expansion mechanism 24.
The heat source expansion mechanism 24 adjusts a flow rate of the refrigerant flowing through the heat source refrigerant flow path 20 and decompresses the refrigerant by controlling an opening degree. The heat source expansion mechanism 24 has one end connected to the heat source heat exchanger 23. The other end of the heat source expansion mechanism 24 is connected to the first shutoff valve 25. The opening degree of the heat source expansion mechanism 24 can be controlled by the control unit (not illustrated).
The first shutoff valve 25 is a valve provided at a connecting portion between the heat source refrigerant flow path 20 and the first connecting pipe 6. When the first shutoff valve 25 is closed, a flow of the refrigerant between the heat source refrigerant flow path 20 and the first connecting pipe 6 is restricted. The first shutoff valve 25 is, for example, a manually operated valve. In the present embodiment, the first shutoff valve 25 is a three-way valve including a service port communicable with the outside of the refrigerant circuit 10.
The second shutoff valve 26 is a valve provided at a connecting portion between the heat source refrigerant flow path 20 and the second connecting pipe 7. When the second shutoff valve 26 is closed, a flow of the refrigerant between the heat source refrigerant flow path 20 and the second connecting pipe 7 is restricted. The second shutoff valve 26 is, for example, a manually operated valve. In the present embodiment, the second shutoff valve 26 is a three-way valve including a service port communicable with the outside of the refrigerant circuit 10.
The first shutoff valve 25 and the second shutoff valve 26 are closed at a time of shipment at a manufacturing factory, and are opened at an end of an installation work of the air conditioner 1. After the end of the installation work, the first shutoff valve 25 and the second shutoff valve 26 are normally kept open.
The accumulator 27 is a container that stores a surplus refrigerant generated in the refrigerant circuit 10 in accordance with a change in an operation load of the utilization unit 3. The accumulator 27 is provided between the port P3 of the flow path switching mechanism 22 and the suction pipe 21a of the compressor 21. The accumulator 27 is an example of a refrigerant storage container.
In the heat source unit 2 as a single unit not connected to any of the utilization unit 3 and the connecting pipes 6 and 7, the refrigerant is filled in the heat source refrigerant flow path 20. The amount of the refrigerant filled in the heat source refrigerant flow path 20 is an amount of the refrigerant filled in the refrigerant circuit 10 for the air conditioner 1 to execute the refrigeration cycle operation with required performance. Specifically, a filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20 satisfies the following relationship of (Formula 1) between a volume V2 (L) of the heat source refrigerant flow path 20 and a design pressure P (MPa) of the heat source refrigerant flow path 20.
[Formula 1]
V1×a≤V2≤V1×b (1)
a=0.078×P2−2.111×P+15.771 (2)
b=0.055×P2−1.768×P+16.144 (3)
V2, which is the volume of the heat source refrigerant flow path 20, is a volume of a space in which the compressor 21, the flow path switching mechanism 22, the heat source heat exchanger 23, the heat source expansion mechanism 24, the first shutoff valve 25, the second shutoff valve 26, and the accumulator 27 are connected to each other by using the refrigerant pipe 20a and are closed from the outside by the first shutoff valve 25 and the second shutoff valve 26.
In the present embodiment, the design pressure P (MPa) of the heat source refrigerant flow path 20 is 10 MPa or more and 14 MPa or less.
A volume V3 (L) of the accumulator 27 may satisfy the following relationship of (Formula 2) with the volume V2 (L) of the heat source refrigerant flow path 20.
0.4×V2≤V3<0.9×V2 [Formula 2]
The heat source refrigerant flow path 20 is typically filled with the refrigerant at a manufacturing factory of the heat source unit 2. When the first shutoff valve 25 and the second shutoff valve are closed after the refrigerant is filled, the refrigerant is prevented from leaking from the heat source refrigerant flow path 20 after the heat source unit 2 is shipped from the manufacturing factory until the air conditioner 1 is installed.
The connecting pipes 6 and 7 are connection pipes connecting the heat source refrigerant flow path 20 and the utilization refrigerant flow path 30 (in other words, the heat source unit 2 and the utilization unit 3). The heat source refrigerant flow path 20, the utilization refrigerant flow path 30, the first connecting pipe 6, and the second connecting pipe 7 are connected to constitute the refrigerant circuit 10.
The length of each of the connecting pipes 6 and 7 is arbitrarily changed in accordance with a distance between the heat source unit 2 and the utilization unit 3 or the like with an upper limit of about 100 m.
Next, a description will be given of operations of components of the air conditioner 1 in an air conditioning operation.
During the cooling operation, the flow path switching mechanism 22 is controlled to the first state. The opening degree of the heat source expansion mechanism 24 is controlled in accordance with a load of the utilization heat exchanger 31.
In this state, when the compressor 21 is activated, the low-pressure refrigerant in the refrigeration cycle is sucked from the suction pipe 21a of the compressor 21, compressed, and discharged from the discharge pipe 21b as a high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor 21 is sent to the heat source heat exchanger 23 via the flow path switching mechanism 22, exchanges heat with the heat source air, and is cooled. In other words, the heat source heat exchanger 23 functions as a radiator. The high-pressure refrigerant cooled in the heat source heat exchanger 23 is decompressed when passing through the heat source expansion mechanism 24 to become a low-pressure refrigerant in a gas-liquid two-phase state. The low-pressure refrigerant in the gas-liquid two-phase state is sent to the utilization unit 3 via the first shutoff valve 25 and the first connecting pipe 6. The refrigerant sent to the utilization unit 3 exchanges heat with air in the air conditioning target space to be heated in the utilization heat exchanger 31, and evaporates to become a low-pressure refrigerant. In other words, the utilization heat exchanger 31 functions as an evaporator. The low-pressure refrigerant heated in the utilization heat exchanger 31 is sent to the heat source unit 2 via the second connecting pipe 7, and flow into the accumulator 27 via the second shutoff valve 26 and the flow path switching mechanism 22. The low-pressure refrigerant having flowed into the accumulator 27 is sucked into the compressor 21 again.
During the heating operation, the flow path switching mechanism 22 is controlled to the second state. The heat source expansion mechanism 24 is controlled to have an opening degree at which the refrigerant can be decompressed to such a pressure as to be evaporated in the heat source heat exchanger 23.
In this state, when the compressor 21 is activated, the low-pressure refrigerant in the refrigeration cycle is sucked from the suction pipe 21a of the compressor 21, compressed, and discharged from the discharge pipe 21b as a high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor 21 is sent to the utilization unit 3 via the flow path switching mechanism 22, the second shutoff valve 26, and the second connecting pipe 7. The high-pressure refrigerant sent to the utilization unit 3 exchanges heat with air in the air conditioning target space in the utilization heat exchanger 31 to be cooled. In other words, the utilization heat exchanger 31 functions as a radiator. The high-pressure refrigerant cooled in the utilization heat exchanger 31 is sent to the heat source unit 2 via the first connecting pipe 6. The refrigerant sent to the heat source unit 2 passes through the first shutoff valve 25, is thereafter decompressed when passing through the heat source expansion mechanism 24 to become a low-pressure refrigerant in a gas-liquid two-phase state, and flows into the heat source heat exchanger 23. The low-pressure refrigerant in the gas-liquid two-phase state that has flowed into the heat source heat exchanger 23 exchanges heat with the heat source air and is heated to evaporate and become a low-pressure refrigerant. In other words, the heat source heat exchanger 23 functions as an evaporator. The low-pressure refrigerant heated by the heat source heat exchanger 23 flows into the accumulator 27 via the flow path switching mechanism 22. The low-pressure refrigerant having flowed into the accumulator 27 is sucked into the compressor 21 again.
Next, a method of filling the refrigerant circuit 10 with the refrigerant in the installation work of the air conditioner 1 will be described.
The installation work of the air conditioner 1 includes a step of installing the heat source unit 2 and the utilization unit 3 at the installation site, and a step of connecting the heat source refrigerant flow path 20 and the utilization refrigerant flow path 30 via the connecting pipes 6 and 7.
In the air conditioner 1, since the heat source refrigerant flow path 20 of the heat source unit 2 is filled with the refrigerant, the heat source refrigerant flow path 20 and the utilization refrigerant flow path 30 are connected via the connecting pipes 6 and 7, and thus, the refrigerant filled in the heat source unit 2 is sent to the utilization unit 3 via the connecting pipes 6 and 7 to be filled in the refrigerant circuit 10. As described above, in the installation work of the air conditioner 1, the heat source refrigerant flow path 20 and the utilization refrigerant flow path 30 are connected via the connecting pipes 6 and 7, and thus, the refrigerant circuit 10 is filled with the refrigerant. Therefore, the work of filling the refrigerant circuit 10 with the refrigerant from the outside is unnecessary. Therefore, the air conditioner 1 including the heat source unit 2 allows the installation work to be performed efficiently.
The heat source unit 2 is connected to the utilization unit 3 and constitutes the air conditioner 1. The heat source unit 2 includes the compressor 21, the heat source heat exchanger 23, the first shutoff valve 25, the second shutoff valve 26, the heat source refrigerant flow path 20, and the refrigerant. The heat source refrigerant flow path 20 is a flow path in which the compressor 21, the heat source heat exchanger 23, the first shutoff valve 25, and the second shutoff valve 26 are connected by the refrigerant pipe 20a. The heat source refrigerant flow path 20 is filled with the refrigerant. The refrigerant includes carbon dioxide.
The filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20, the volume V2 (L) of the heat source refrigerant flow path 20, and the design pressure P (MPa) of the heat source refrigerant flow path 20 satisfy the following relationship of (Formula 1).
[Formula 1]
V1×a≤V2≤V1×b (1)
a=0.078×P2−2.111×P+15.771 (2)
b=0.055×P2−1.768×P+16.144 (3)
The carbon dioxide refrigerant is known to have a more rapid increase in pressure when becoming supercritical compare to other refrigerants.
As illustrated in
On the other hand, as illustrated in
In the heat source unit 2, the relationship between the filling amount V1 of the refrigerant and the volume V2 of the heat source refrigerant flow path 20 is set on the basis of (Formula 1) obtained from the characteristics between the temperature and the pressure of the carbon dioxide refrigerant and an assumed temperature range of the refrigerant. Here, the assumed temperature range of the refrigerant is 50° C. or more and 70° C. or less. The temperature 50° C. is a temperature assumed in a place such as a warehouse or the like where the heat source unit 2 is stored (for example, the temperature in the warehouse) in summer or the like. The temperature 70° C. is an upper limit of a refrigerant temperature raised by the outside air temperature or direct sunlight in a place such as the warehouse or the like where the heat source unit 2 is stored.
(2) of Formula 1 determines a specific volume at which each component constituting the heat source refrigerant flow path 20 having the design pressure P is prevented from being damaged due to a pressure rise when the temperature of the refrigerant is 50° C.
(3) of Formula 1 determines a specific volume at which an increase in size of the heat source refrigerant flow path 20 having the design pressure P is suppressed when the temperature of the refrigerant is 70° C., the heat source refrigerant flow path 20 having a volume larger than necessary.
When the design pressure P of the heat source refrigerant flow path 20 is arbitrarily selected at an arbitrary refrigerant amount V1, the volume V2 of the heat source refrigerant flow path 20 is set to satisfy equal to or more than the volume V1×a calculated on the left side (1) of Formula 1 and equal to or less than the volume V1×b calculated on the right side (1) of Formula 1. Thus, occurrence of pressure abnormality in the refrigerant flow path due to the carbon dioxide refrigerant filled in the heat source refrigerant flow path 20 becoming supercritical is suppressed while an increase in size of the heat source refrigerant flow path 20 is suppressed.
Therefore, the heat source unit 2 suppresses occurrence of pressure abnormality in the refrigerant flow path due to the carbon dioxide refrigerant filled in the heat source refrigerant flow path 20 becoming supercritical while suppressing an increase in size of the heat source refrigerant flow path 20.
The design pressure P is 10 MPa or more and 14 MPa or less.
A point calculated by (2) of Formula 1 when the pressure of the refrigerant becomes 14 MPa is a first point Pa in
The volume V3 (L) of the accumulator 27 preferably satisfies the following relationship of (Formula 2) with the volume V2 (L) of the heat source refrigerant flow path 20.
0.4×V2≤V3<0.9×V2 [Formula 2]
Since the heat source unit 2 can store the refrigerant not only in the heat source refrigerant flow path 20 but also in the accumulator 27 in the heat source refrigerant flow path 20, the volume V2 can be sufficiently secured to effectively suppress the occurrence of pressure abnormality in the refrigerant flow path.
The heat source unit 2 further includes the flow path switching mechanism 22 that switches the direction in which the refrigerant flows in the heat source refrigerant flow path 20, and the accumulator 27 that stores the refrigerant.
The accumulator 27 can store not only the filled refrigerant but also a surplus refrigerant generated due to a change in an operation load generated between the cooling operation and the heating operation.
The air conditioner 1 may be a multi-type air conditioner including one heat source unit 2 and a plurality of utilization units 3.
The air conditioner 1 is not required to include the flow path switching mechanism 22 and, may be configured to perform only one of the cooling operation or the heating operation as the air conditioning operation.
The installation work of the air conditioner 1 may further include a step of additionally filling the refrigerant after the step of connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7. The step of additionally filling the refrigerant is performed when the lengths of the connecting pipes 6 and 7 used for connecting the heat source unit 2 and the utilization unit 3 are more than or equal to a predetermined first length L1.
As described above, the heat source refrigerant flow path 20 of the heat source unit 2 is filled with the refrigerant in an amount (hereinafter, also referred to as required refrigerant amount) that enables the air conditioner 1 to execute the refrigeration cycle operation with the required performance by being filled in the refrigerant circuit 10. However, when the heat source unit 2 and the utilization unit 3 are disposed away from each other, it is necessary to connect the heat source unit 2 and the utilization unit 3 by using the connecting pipes 6 and 7 longer than usually. In such a case, the capacity of the refrigerant circuit 10 becomes larger than initially assumed, and the refrigerant filled in the heat source refrigerant flow path 20 of the heat source unit 2 may be insufficient for the required refrigerant amount. Therefore, in the air conditioner 1 according to Modification A3, a maximum length by which the refrigerant filled in the heat source refrigerant flow path 20 does not become less than the required refrigerant amount is set in advance as the first length L1. In other words, the lengths of the connecting pipes 6 and 7 are changed in accordance with the installation positions of the heat source unit 2 and the utilization unit 3. The connecting pipes 6 and 7 each have, as one of variations in length, the first length L1 that does not require additional filling of the refrigerant into the refrigerant circuit 10 formed by connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7. The heat source unit 2 is filled with an amount of refrigerant corresponding to the required refrigerant amount in the refrigerant circuit 10 when the connecting pipes 6 and 7 have the first length L1.
Thus, a worker or the like who performs the installation work of the air conditioner 1 determines whether the lengths of the connecting pipes 6 and 7 required for the installation work of the air conditioner 1 are more than or equal to the first length L1.
When the lengths of the connecting pipes 6 and 7 are less than the first length L1, the refrigerant filled in the heat source refrigerant flow path 20 is more than the required refrigerant amount, and thus, the step of additionally filling the refrigerant is unnecessary. Therefore, the step of additionally filling the refrigerant is not performed, and after the step of connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7 is performed, the installation work ends. In other words, the filling amount of refrigerant filled in the heat source refrigerant flow path 20 of the heat source unit 2 is more than the required refrigerant amount in the refrigerant circuit 10 formed by connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7 when the connecting pipes 6 and 7 are shorter than the first length L1.
On the other hand, when the lengths of the connecting pipes 6 and 7 are more than or equal to the first length L1, the refrigerant filled in the heat source refrigerant flow path 20 is insufficient for the required refrigerant amount, and thus, the step of additionally filling the refrigerant is necessary. Therefore, the step of additionally filling the refrigerant is performed, and the refrigerant circuit 10 is additionally filled with an amount of refrigerant corresponding to the lengths of the connecting pipes 6 and 7. The refrigerant is additionally filled, for example, from the service port of the first shutoff valve 25 or the second shutoff valve 26.
When the air conditioner 1 is a pair type air conditioner including one heat source unit 2 and one utilization unit 3, the first length L1 is, for example, about 15 m. When the air conditioner 1 is a multi-type air conditioner including one heat source unit 2 and a plurality of utilization units 3, the first length L1 is, for example, from about 30 m to about 70 m.
The heat source refrigerant flow path 20 of the heat source unit 2 may further include a receiver that stores the surplus refrigerant. In this case, V3 includes a volume of the receiver in addition to the volume of the accumulator 27.
A heat source unit 2a according to a second embodiment will be described focusing on differences from the heat source unit 2. Similarly to the heat source unit 2, the heat source unit 2a is connected to one or more utilization units 3 by using the first connecting pipe 6 and the second connecting pipe 7 to constitute an air conditioner 1a. Hereinafter, characteristics that are the same as or correspond to the characteristics of the first embodiment are denoted by the same reference signs, and description thereof is omitted.
A main difference between the heat source unit 2a and the heat source unit 2 is that the heat source unit 2a further includes a refrigerant amount adjuster 28. The refrigerant amount adjuster 28 stores the refrigerant to be filled in the installation work of the air conditioner 1a, and stores the surplus refrigerant generated in the refrigerant circuit 10 in accordance with the change in the operation load of the utilization unit 3 or the like. The refrigerant amount adjuster 28 is included in the heat source refrigerant flow path 20 of the heat source unit 2a. As a result, in the heat source unit 2a, the heat source refrigerant flow path 20 is filled with a larger amount of refrigerant than in the heat source unit 2. The refrigerant amount adjuster 28 includes a refrigerant storage container 28a, a pressure adjustment valve 28b, a check valve 28c, an electromagnetic valve 28d, and an expansion mechanism 28e.
The refrigerant storage container 28a is a container (tank) that stores at least a part of the refrigerant to be filled in the heat source refrigerant flow path 20 and stores the surplus refrigerant generated in the refrigerant circuit 10. The refrigerant storage container 28a has a first port 28aa and a second port 28ab. The refrigerant storage container 28a is an example of a refrigerant storage container.
The first port 28aa is a port provided for adjusting the pressure inside the refrigerant storage container 28a. The first port 28aa is connected to, via a pressure adjusting pipe 20b, the refrigerant pipe connected to the port P3 of the flow path switching mechanism 22 and the accumulator 27 and the discharge pipe 21b of the compressor 21.
The second port 28ab is a port through which the refrigerant flows. The second port 28ab is connected to the suction pipe 21a of the compressor 21 via the refrigerant pipe 20a.
The pressure adjustment valve 28b is a valve that prevents the pressure of the refrigerant in the refrigerant storage container 28a from becoming excessively high. The pressure adjustment valve 28b is provided in the pressure adjusting pipe 20b connected to the refrigerant pipe 20a connected to the port P3 of the flow path switching mechanism 22 and the accumulator 27. The pressure adjustment valve 28b opens when the pressure of the refrigerant in the refrigerant storage container 28a reaches or exceeds a predetermined value, and releases the high-pressure refrigerant to the accumulator 27.
The check valve 28c and the electromagnetic valve 28d are valves used to increase the pressure of the refrigerant in the refrigerant storage container 28a. The check valve 28c and the electromagnetic valve 28d are provided in the pressure adjusting pipe 20b connected to the discharge pipe 21b of the compressor 21. When the electromagnetic valve 28d is opened during the operation of the compressor 21, a high-pressure refrigerant discharged from the compressor 21 is sent to the refrigerant storage container 28a. The electromagnetic valve 28d is opened typically when the refrigerant circuit 10 is filled with the refrigerant in the refrigerant storage container 28a. The check valve 28c prevents the refrigerant from flowing from the refrigerant storage container 28a to the discharge pipe 21b of the compressor 21. The electromagnetic valve 28d can be opened and closed by a control unit (not illustrated). The check valve 28c and the electromagnetic valve 28d may be a flow rate adjustment mechanism including an electric valve.
The expansion mechanism 28e adjusts a flow rate of the refrigerant flowing through the refrigerant pipe 20a connecting the suction pipe 21a of the compressor 21 and the refrigerant storage container 28a and decompresses the refrigerant. An opening degree of the expansion mechanism 28e can be controlled by a control unit (not illustrated).
Similarly to the heat source unit 2, in the heat source unit 2a, the refrigerant is filled in the heat source refrigerant flow path 20 as a single unit not connected to any of the utilization unit 3 and the connecting pipes 6 and 7. The amount of the refrigerant filled in the heat source refrigerant flow path 20 is an amount of the refrigerant filled in the refrigerant circuit 10 for the air conditioner la to execute the refrigeration cycle operation with required performance. At this time, the filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20 satisfies the above relationship of (Formula 1) between the volume V2 (L) of the heat source refrigerant flow path 20 and the design pressure P (MPa) of the heat source refrigerant flow path 20.
In the heat source unit 2a, V3 includes a volume of the refrigerant storage container 28a in addition to the volume of the accumulator 27. V3 (L) satisfies the above relationship of (Formula 2) with the volume V2 (L) of the heat source refrigerant flow path 20.
In both the cooling operation and the heating operation, the opening degrees of the expansion mechanism 28e and the electromagnetic valve 28d are controlled to be fully open or nearly fully open at the time of supplying the refrigerant. When the refrigerant supply is finished, the expansion mechanism 28e and the electromagnetic valve 28d are controlled in opening degree to be fully closed or nearly fully closed. As a result, a necessary refrigerant is supplied into the refrigerant circuit 10 of the air conditioner 1a. Of the refrigerant filled in the refrigerant storage container 28a in advance, a surplus refrigerant is reserved in the refrigerant storage container 28a without being supplied into the refrigerant circuit 10.
The operation of the other components of the air conditioner la in the air conditioning operation is similar to that of the air conditioner 1, and will not be described.
The installation work of the air conditioner 1a further includes a step of sending the refrigerant stored in the refrigerant storage container 28a to the refrigerant circuit 10, in addition to the step of installing the heat source unit 2 and the utilization unit 3 at the installation sites, and the step of connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7.
In the step of sending the refrigerant stored in the refrigerant storage container 28a to the refrigerant circuit 10, the opening degrees of the heat source expansion mechanism 24, the electromagnetic valve 28d, and the expansion mechanism 28e are controlled to be fully open or nearly fully open. When the compressor 21 is activated in this state, the high-pressure refrigerant discharged from the compressor 21 passes through the first port 28aa and pushes out the refrigerant stored in the refrigerant storage container 28a from the second port 28ab. As a result, the refrigerant having passed through the expansion mechanism 28e is sucked from the suction pipe 21a of the compressor 21 to be filled in the refrigerant circuit 10. When the compressor 21 is stopped, this step ends.
In the air conditioner 1a, since the heat source unit 2a further includes the refrigerant amount adjuster 28, the heat source refrigerant flow path 20 is filled with more refrigerant than in the heat source unit 2. Therefore, in the air conditioner 1a including the heat source unit 2a, even when the plurality of utilization units 3 is provided, the heat source unit 2a can sufficiently store the required refrigerant amount in the heat source refrigerant flow path 20.
The heat source unit 2a is connected to the utilization unit 3 and constitutes the air conditioner 1a. The heat source unit 2a includes the compressor 21, the heat source heat exchanger 23, the first shutoff valve 25, the second shutoff valve 26, the heat source refrigerant flow path 20, and the refrigerant. The heat source refrigerant flow path 20 of the heat source unit 2a is a flow path in which the compressor 21, the heat source heat exchanger 23, the first shutoff valve 25, the second shutoff valve 26, and the refrigerant amount adjuster 28 are connected by the refrigerant pipe 20a. The heat source refrigerant flow path 20 is filled with the refrigerant. The refrigerant includes carbon dioxide.
The filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20, the volume V2 (L) of the heat source refrigerant flow path 20, and the design pressure P (MPa) of the heat source refrigerant flow path 20 satisfy the above relationship of (Formula 1).
Therefore, the heat source unit 2a also suppresses occurrence of pressure abnormality in the refrigerant flow path due to the filled carbon dioxide refrigerant becoming supercritical while suppressing an increase in size of the heat source refrigerant flow path 20.
The volume V3 (L) of the accumulator 27 and the refrigerant storage container 28a preferably satisfies the above relationship of (Formula 3) with the volume V2 (L) of the heat source refrigerant flow path 20.
Since the heat source unit 2a can store the refrigerant not only in the heat source refrigerant flow path 20 but also in the accumulator 27 and the refrigerant storage container 28a in the heat source refrigerant flow path 20, the volume V2 can be sufficiently secured to effectively suppress the occurrence of pressure abnormality in the refrigerant flow path.
The air conditioner 1a and the heat source refrigerant flow path 20 may also have the characteristics of Modifications A1 to A5 described above.
The embodiments of the present disclosure have been described above. It will be understood that various changes to modes and details can be made without departing from the gist and scope of the present disclosure recited in the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-158181 | Sep 2022 | JP | national |
| 2022-181659 | Nov 2022 | JP | national |
The present application is a bypass continuation of International Application PCT/JP2023/035004, filed Sep. 26, 2023, which claims priority to Japanese patent application JP 2022-158181, filed Sep. 30, 2022, and Japanese patent application JP 2022-181659, filed Nov. 14, 2022, the entire contents of each of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/035004 | Sep 2023 | WO |
| Child | 19094874 | US |
