Void fraction sensor, flowmeter using the same, and cryogenic liquid transfer pipe

1 . A void fraction sensor for measuring a void fraction of a cryogenic liquid, comprising:

a pipe having a flow channel in which a cryogenic liquid flows;

a first electrode and a second electrode disposed outside the flow channel;

at least one intermediate electrode disposed in the flow channel and between the first electrode and the second electrode, the at least one intermediate electrode configured to measure capacitance with at least one of the first electrode and the second electrode, wherein

the at least one intermediate electrode divides the flow channel is divided into at least two divided flow channels between the first electrode and the second electrode, and

the first electrode faces the at least one intermediate electrode via one of the divided flow channels and the second electrode faces the at least one intermediate electrode via another one of the divided flow channels.

2 . The void fraction sensor according to claim 1 , wherein

the at least one intermediate electrode is provided facing the first electrode and the second electrode along the axial direction of the flow channel.

3 . The void fraction sensor according to claim 1 , wherein

the at least one intermediate electrode connects two points on an inner peripheral surface, the two points facing each other in a radial direction in the flow channel.

4 . The void fraction sensor according to claim 1 , wherein

a distance between the first electrode and the at least one intermediate electrode is electrically equal to a distance between the second electrode and the at least one intermediate electrode.

5 . The void fraction sensor according to claim 1 , wherein

the at least one intermediate electrode comprises a plurality of intermediate electrodes, and distances between each of the plurality of intermediate electrodes are electrically equal to each other.

6 . The void fraction sensor according to claim 5 , wherein

a distance between the first electrode and the intermediate electrode of the plurality of intermediate electrodes closest to the first electrode is electrically equal to a distance between the second electrode and the intermediate electrode of the plurality of intermediate electrodes closest to the second electrode.

7 . The void fraction sensor according to claim 5 , wherein

the distances between each of the plurality of intermediate electrodes are electrically equal to at least one of the distance between the first electrode and the intermediate electrode of the plurality of intermediate electrodes closest to the first electrode and the distance between the second electrode and the intermediate electrode of the plurality of intermediate electrodes closest to the second electrode.

8 . The void fraction sensor according to claim 1 , wherein

the pipe comprises a support that supports the at least one intermediate electrode, and

the at least one intermediate electrode is incorporated in the support.

9 . The void fraction sensor according to claim 1 , wherein

the pipe comprises a support that supports the at least one intermediate electrode, and

the at least one intermediate electrode is mounted on one surface or both surfaces of the support to face one or both of the first electrode and the second electrode, and is covered with an insulating film.

10 . The void fraction sensor according to claim 8 , wherein

the support is integrally formed with the pipe.

11 . A void fraction sensor according to claim 1 , wherein

an inner diameter of the flow channel is at least 50 mm.

12 . A flowmeter for measuring a flow rate of a cryogenic liquid flowing in a flow channel of a pipe, comprising:

the void fraction sensor according to claim 1 ; and

a flow velocity meter configured to measure a flow velocity of the cryogenic liquid flowing in the flow channel.

13 . A cryogenic liquid transfer pipe comprising:

the flowmeter according to claim 12 .