Patent Application
20240272120
The present disclosure relates to a discharging device used for determining the likelihood of occurrence of a disproportionation reaction in a refrigerant. The present disclosure further relates to a refrigerant evaluation device and a refrigerant evaluation method using such a discharging device.
Non-Patent Document 1 (Japanese Industrial Standard (JIS) Z 8834) discloses a method for determining minimum ignition energy of dust/air mixtures. This determination method is used for determining whether a mixture of flammable dust and air is easily ignited by an electric discharge.
A discharging device according to a first aspect includes a first electrode and a second electrode, a capacitor, and a reactor unit. The first electrode and the second electrode are separated from each other. The capacitor stores energy to apply a first voltage between the first electrode and the second electrode. The reactor unit includes a first reactor and a second reactor. The reactor unit inductively generates a second voltage to be applied between the first electrode and the second electrode to start discharge of the energy between the first electrode and the second electrode.
The refrigerant chamber 70 is a chamber having an internal space. The internal space is capable of containing a high-pressure refrigerant 73. The refrigerant 73 is a measurement target sample.
A first electrode 71 and a second electrode 72 are provided in the internal space of the refrigerant chamber 70. The first electrode 71 and the second electrode 72 cooperate with each other to cause discharge in the refrigerant 73. The first electrode 71 and the second electrode 72 are disposed to be separated from each other by a separation distance D. Each of the first electrode 71 and the second electrode 72 has a diameter φ.
A pressure sensor 74 for acquiring the pressure of the refrigerant 73 is disposed in the refrigerant chamber 70.
The charging device 10 is for accumulating energy E to be applied to the refrigerant 73 by discharge. The charging device 10 stores the energy E in a capacitor 31 of the discharging device 20, which will be described later.
The charging device 10 includes a DC power source 11, a resistor 12, and a charging switch 13.
The DC power source 11 has a positive terminal 11a and a negative terminal 11b, and outputs a DC voltage V0 between the positive terminal 11a and the negative terminal 11b.
The resistor 12 is connected to at least one of the positive terminal 11a and the negative terminal 11b.
The charging switch 13 transmits the DC voltage V0 output from the DC power source 11 to the capacitor 31 of the discharging device 20 or disconnects the DC voltage V0 from the capacitor 31. As a result, the charging switch 13 charges the capacitor 31. The charging switch 13 may be, for example, a switch or a relay, which is a mechanical switching element, or may be a semiconductor element such as a power transistor.
The discharging device 20 is for causing discharge between the first electrode 71 and the second electrode 72, thereby applying the energy E to the refrigerant 73.
The discharging device 20 includes an energy accumulation unit 30 and a reactor unit 40. The discharging device 20 does not include a semiconductor element.
The discharging device 20 include a discharge path DP. The discharge path DP extends from a node N1 connected to the second electrode 72 to a node N5 connected to the first electrode 71 via a node N2, a node N3, and a node N4. The discharge path DP does not include a semiconductor element such as a power transistor.
The energy accumulation unit 30 includes the capacitor 31. The capacitor 31 has a first terminal 31a and a second terminal 31b. The first terminal 31a is connected to the node N3. The second terminal 31b is connected to the node N2. The energy accumulation unit 30 does not include a semiconductor element such as a power transistor.
The node N3 is connected to the positive terminal 11a of the DC power source 11 via the resistor 12 and the charging switch 13. The node N2 is connected to the negative terminal 11b of the DC power source 11.
The capacitor 31 has a capacitance C. By the charging switch 13 being closed, the capacitor 31 is charged. As a result, the capacitor 31 accumulates an electric charge Q. Then, even when the charging switch 13 is opened, the capacitor 31 holds a first voltage V1 between the first terminal 31a and the second terminal 31b by the action of the electric charge Q. At this time, the energy E stored in the capacitor 31 is expressed by the following equation: E=(½)×C×(V1)2.
When the discharge does not occur in the refrigerant chamber 70, the first voltage V1 is applied between the first electrode 71 and the second electrode 72.
The reactor unit 40 is for starting discharge between the first electrode 71 and the second electrode 72. The reactor unit 40 inductively generates a large second voltage V2. Even when the first voltage V1 is applied between the first electrode 71 and the second electrode 72, while no discharge occurs, a current I does not flow between the first electrode 71 and the second electrode 72. In this state, by the large second voltage V2 generated by the reactor unit 40 being applied between the first electrode 71 and the second electrode 72, plasma is generated in the refrigerant 73, and conduction occurs between the first electrode 71 and the second electrode 72. Then, the electric charge Q stored in the capacitor 31 moves between the first electrode 71 and the second electrode 72, thereby causing discharge in the refrigerant 73.
The reactor unit 40 includes a first reactor 50 and a second reactor 60. The first reactor 50 and the second reactor 60 are connected in series.
The first reactor 50 includes a first reactor core 51, a first primary coil 54, a first secondary coil 53, a first charging capacitor 55, and a first discharging switch 56. The material of the first reactor core 51 is ferrite. The first reactor core 51 has a magnetic permeability μ. The first primary coil 54 and the first secondary coil 53 are both wound around the first reactor core 51. The first secondary coil 53 has a number of turns N. The material of the first secondary coil 53 is selected from copper and silver. The first discharging switch 56 may be, for example, a switch or a relay, which is a mechanical switching element, or may be a semiconductor element such as a power transistor.
The second reactor 60 includes a second reactor core 61, a second primary coil 64, a second secondary coil 63, a second charging capacitor 65, and a second discharging switch 66. The material of the second reactor core 61 is ferrite. The second reactor core 61 has the magnetic permeability μ. The second primary coil 64 and the second secondary coil 63 are both wound around the second reactor core 61. The second secondary coil 63 has the number of turns N. The material of the second secondary coil 63 is selected from copper and silver. The second discharging switch 66 may be, for example, a switch or a relay, which is a mechanical switching element, or may be a semiconductor element such as a power transistor.
The first secondary coil 53 has one end connected to the node N3 and the other end connected to the node N4. The second secondary coil 63 has one end connected to the node N4 and the other end connected to the node N5. The reactor unit 40 does not include a semiconductor element such as a power transistor at least in the discharge path DP extending from the node N3 to the node N5.
The first charging capacitor 55 is charged by an unillustrated charging circuit. The first discharging switch 56 causes a transient current to flow through the first primary coil 54 by discharging the electric charge accumulated in the first charging capacitor 55. This transient current generates an induced voltage in the first secondary coil 53.
The second charging capacitor 65 is charged by an unillustrated charging circuit. The second discharging switch 66 causes a transient current to flow through the second primary coil 64 by discharging the electric charge accumulated in the second charging capacitor 65. This transient current generates an induced voltage in the second secondary coil 63.
The large second voltage V2 is generated by the induced voltages of the plurality of coils, which are the first secondary coil 53 and the second secondary coil 63.
The arithmetic unit 80 is a computer including a central processing unit and a storage device. The arithmetic unit 80 calculates the degree of the disproportionation reaction in the refrigerant 73, based on at least the output of the pressure sensor 74.
The arithmetic unit 80 may further use outputs of a voltmeter 81 and an ammeter 82 to calculate the degree of the disproportionation reaction in the refrigerant 73. The voltmeter 81 measures a third voltage V3, which is a potential difference between the first electrode 71 and the second electrode 72. The ammeter 82 measures the current I flowing through the first electrode 71 or the second electrode 72. The ammeter 82 is disposed, for example, in a section sandwiched between the node N1 and the node N2. The ammeter 82 has almost no resistance to be applied to the discharge path DP. Therefore, it may be considered that there is no semiconductor element caused by the ammeter 82 in the section sandwiched between the node N1 and the node N2.
The arithmetic unit 80 may perform control to open and close at least one of the charging switch 13, the first discharging switch 56, and the second discharging switch 66.
The pressure of the refrigerant 73 contained in the refrigerant chamber 70 is set to, for example, 1 MPa or more and 10 MPa or less.
The first voltage V1 is, for example, 100 V or more and 2000 V or less.
The second voltage V2 is, for example, 20 kV or more and 100 kV or less.
The third voltage V3 is, for example, 20 kV or more and 100 kV or less.
The current I generated by discharge is, for example, 50 A or more.
The diameter φ of each of the first electrode 71 and the second electrode 72 is, for example, 3 mm or less. Preferably, the diameter φ is 1 mm or less. More preferably, the diameter φ is 0.5 mm or less.
The separation distance D between the first electrode 71 and the second electrode 72 is, for example, 10 μm or more.
The capacitance C is, for example, 30 μF or more.
The magnetic permeability μ of each of the first reactor core 51 and the second reactor core 61 is, for example, 250 H/m or more.
The number of turns N of each of the first secondary coil 53 and the second secondary coil 63 is, for example, 20 or more and 100 or less.
The energy E is, for example, 1 mJ or more and 5000 J or less. Preferably, the energy E is 1 mJ or more and 2500 J or less.
The procedure to evaluate the refrigerant 73 includes the following steps.
In a first step, the refrigerant 73 is introduced into the internal space of the refrigerant chamber 70.
In a second step, the arithmetic unit 80 acquires the pressure of the refrigerant 73 as a first pressure P1.
In a third step, the capacitor 31 is charged by temporarily closing the charging switch 13. This causes the first voltage V1 held by the capacitor 31 to be applied between the first electrode 71 and the second electrode 72. However, discharge is yet to occur in the refrigerant 73.
In a fourth step, the reactor unit 40 inductively generates the second voltage V2 by simultaneously closing the first discharging switch 56 and the second discharging switch 66. The second voltage V2 is applied between the first electrode 71 and the second electrode 72.
In a fifth step, plasma is generated in the refrigerant 73 by the second voltage V2, and thus, conduction occurs between the first electrode 71 and the second electrode 72.
In a sixth step, the electric charge Q accumulated in the capacitor 31 flows between the first electrode 71 and the second electrode 72, and thus, discharge is started in the refrigerant 73.
In a seventh step, the arithmetic unit 80 acquires the pressure of the refrigerant 73 as a second pressure P2.
In an eighth step, the arithmetic unit 80 calculates the degree of the disproportionation reaction in the refrigerant 73, based on the first pressure P1 and the second pressure P2. When the refrigerant 73 obtains the energy E from the discharge, a chemical reaction occurs in the refrigerant 73, which causes a change in the number of molecules of the refrigerant 73. The number of molecules of the refrigerant 73 is acquired as a pressure value by the pressure sensor 74. The change in the number of molecules varies depending on the number of refrigerant molecules that can react and that the refrigerant 73 contained in the internal space of the refrigerant chamber 70 initially has. Therefore, based on the first pressure P1 and the second pressure P2, the number of refrigerant molecules that can react and that the refrigerant 73 has when being introduced into the refrigerant chamber 70 is calculated. The number of refrigerant molecules that can react is treated as an index indicating the degree of the disproportionation reaction that has already occurred in the refrigerant 73.
Note that this index may be calibrated by the magnitude of the energy E that the refrigerant 73 has obtained from discharge. The magnitude of energy may be calculated from the third voltage V3 measured by the voltmeter 81 and the current I measured by the ammeter 82.
It is generally difficult to divert a conventional determination method to the purpose of determining the likelihood of occurrence of the disproportionation reaction in the refrigerant. The reason is that discharge is unlikely to occur in an environment in which a high pressure is applied to the refrigerant.
Therefore, in order to determine the likelihood of occurrence of the disproportionation reaction in a certain type of refrigerant, in other words, in order to determine the degree of the disproportionation reaction that has already occurred in a sample refrigerant, a discharging device capable of causing discharge in a high-pressure refrigerant is required.
In the present disclosure, the reactor unit 40 includes two reactors, which are the first reactor 50 and the second reactor 60. Therefore, since the reactor unit 40 can have a large reactance, the reactor unit 40 can generate the large second voltage V2. Therefore, in a case where the high-pressure refrigerant 73 is disposed between the first electrode 71 and the second electrode 72, discharge is started by the second voltage V2, which is the large induced voltage, which can cause the energy E stored in the capacitor 31 to be applied to the refrigerant 73. This enables evaluation of the disproportionation reaction in the refrigerant 73.
Under the condition that the refrigerant 73 is maintained at a high pressure, discharge due to dielectric breakdown is less likely to occur. In order to perform discharge in the high-pressure refrigerant 73, it is necessary to generate plasma in the refrigerant by applying a large voltage to the refrigerant 73. In the present disclosure, by using the two reactors, the large second voltage V2 can be induced. Therefore, discharge due to dielectric breakdown can occur in the high-pressure refrigerant 73.
The material of the first reactor core 51 and the second reactor core 61 is ferrite. Therefore, it is easy to increase the second voltage V2.
The first reactor core 51 and the second reactor core 61 have the large magnetic permeability μ. Therefore, it is easy to increase the second voltage V2.
The first secondary coil 53 and the second secondary coil 63 have the predetermined number of turns. Therefore, by cooperating with the first reactor core 51 and the second reactor core 61, the first secondary coil 53 and the second secondary coil 63 can generate the large second voltage V2.
The material of the first secondary coil 53 and the second secondary coil 63 has low resistivity. Therefore, the loss of the energy E can be reduced.
The discharge path DP does not include a semiconductor element. Therefore, since the discharge path DP can handle a large current exceeding a rated current of about several amperes of the semiconductor element, the discharge path DP can apply the large energy E to the refrigerant 73.
By increasing the magnitude of the energy E applied to the refrigerant 73, the magnitude of the energy E is stabilized, and thus, the reproducibility of the disproportionation reaction occurring in the refrigerant 73 is improved. Therefore, for the specific refrigerant 73, the likelihood of occurrence of the disproportionation reaction can be accurately evaluated.
Furthermore, by changing the magnitude of the energy E applied to the refrigerant 73 over a wide range, it is possible to further improve the accuracy of the evaluation of the likelihood of occurrence of the disproportionation reaction for the specific refrigerant 73. For example, the magnitude of the energy E may be changed from the order of several millijoules (mJ) to the order of several thousand joules (J).
By causing a current to flow through the first primary coil 54 and the second primary coil 64, the second voltage V2 can be induced.
The value of the second voltage V2 is large. Therefore, since the discharging device 20 can apply the large energy E to the refrigerant 73, the magnitude of the energy E received by the refrigerant 73 is stabilized.
The value of the current I involved in discharge is large. Therefore, since the discharging device 20 can apply the large energy E to the refrigerant 73, the magnitude of the energy E received by the refrigerant 73 is stabilized.
The diameter φ of the first electrode 71 and the second electrode 72 is small. Therefore, since the first electrode 71 and the second electrode 72 have small volumes, thermal energy temporarily generated by discharge is less likely to be cooled by a metal material forming the first electrode 71 or the second electrode 72.
A large distance can be maintained as the separation distance D between the first electrode 71 and the second electrode 72. Therefore, the magnitude of the energy E received by the refrigerant 73 is stabilized.
The capacitance C of the capacitor 31 is large. Therefore, since the discharging device 20 can apply the large energy E to the refrigerant 73, the magnitude of the energy E received by the refrigerant 73 is stabilized.
The discharging device 20 can apply the large energy E to the refrigerant. Therefore, the refrigerant evaluation device 100 can stably determine the degree of the disproportionation reaction in the refrigerant 73.
In the above-described embodiment, in the charging device 10, the resistor 12 and the charging switch 13 are both connected to the positive terminal 11a of the DC power source 11. Alternatively, at least one of the resistor 12 and the charging switch 13 may be connected to the negative terminal 11b of the DC power source 11.
In the above-described embodiment, the reactor unit 40 is connected between the node N3 and the node N5, which are present on the side of the positive terminal 11a of the DC power source 11. Alternatively, the reactor unit 40 may be connected between the node N1 and the node N2, which are present on the side of the negative terminal 11b of the DC power source 11.
Although the embodiment of the present disclosure has been described above, it should be understood that various changes can be made on the forms and details without departing from the spirit and scope of the present disclosure described in the claims.
NPL 1: Japanese Industrial Standard (JIS) Z 8834
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-165369 | Oct 2021 | JP | national |
This application is a Continuation of PCT International Application No. PCT/JP2022/037000, filed on Oct. 3, 2022, which claims priority under 35 U.S.C. § 119(a) to Patent Application No. JP 2021-165369, filed in Japan on Oct. 7, 2021, all of which are hereby expressly incorporated by reference into the present application.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2022/037000 | Oct 2022 | WO |
| Child | 18627891 | US |
