JP3670847B2 - Cryogenic fluid density measurement system - Google Patents
Cryogenic fluid density measurement system Download PDFInfo
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- JP3670847B2 JP3670847B2 JP18768698A JP18768698A JP3670847B2 JP 3670847 B2 JP3670847 B2 JP 3670847B2 JP 18768698 A JP18768698 A JP 18768698A JP 18768698 A JP18768698 A JP 18768698A JP 3670847 B2 JP3670847 B2 JP 3670847B2
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- Prior art keywords
- cryogenic fluid
- waveguide
- microwave
- dielectric constant
- density
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Description
【０００１】
【発明の属する技術分野】
本発明は、固体水素と液体水素とがシャーベット状に混合しているスラッシュ水素等の極低温流体（本発明では単に極低温流体と称する）の密度を、マイクロ波を使って測定する密度計測装置に関する。
【０００２】
【従来の技術】
固体水素と液体水素とをシャーベット状に混合してなるスラッシュ水素は、輸送、貯蔵コストの面で液体水素等よりも有利な新燃料として注目されている。このように固体と液体とが混合している極低温流体を例えば宇宙燃料として使う場合などはその正確な密度を知ることが必要となる。
【０００３】
スラッシュ水素のような極低温流体の密度を計測するやり方として、その極低温流体中にマイクロ波をアンテナから導入し極低温流体を通過したマイクロ波を他のアンテナで受け、その間におけるマイクロ波の位相変化からその極低温流体の誘電率を測定し、得られた誘電率から密度を求める方法がある。
【０００４】
すなわち、上記方法を用いれば、固液混相状態の平均値としての誘電率が求まり、得られた誘電率と物性値として与えられている固体単相及び液体単相の誘電率から、固液混合割合を計算し、密度を求めるのである。
このように極低温流体中にマイクロ波をアンテナから導入して他のアンテナで受け、その間のマイクロ波の位相変化から極低温流体の誘電率を測定する原理は次の式によって与えられる。
【０００５】
【数１】
マイクロ波を極低温流体中に導入したり、極低温流体中を通過したマイクロ波を受けるのに従来は図３に示すような導波管１の先にホーンアンテナ２を付けたものが使われていた。マイクロ波は導波管の内面をマイクロ波反射面として導かれ一方のホーンアンテナから出て、他方のホーンアンテナから入って導波管の内面をマイクロ波反射面として測定器具へと導かれる。
【０００７】
【発明が解決しようとする課題】
このように導波管とホーンアンテナを使ってマイクロ波を極低温流体中に導き、その密度を計測する従来の装置では、導波管が比較的細い管であるため、極低温流体が中に含まれている固体のために流動性が悪い場合、極低温流体が細い導波管中に入って行かない場合が生じた。このように導波管中への極低温流体の入り込みにむらがあると先に示した数式中のマイクロ波光路長Ｌが変化し、これが原因で測定された誘電率に誤差を生ずるという問題があった。
【０００８】
そこで本発明は、極低温流体内にマイクロ波を導入して同極低温流体の誘電率を測定し、得られた誘電率を基に同極低温流体の密度を計測するマイクロ波密度計測装置において、極低温流体内にマイクロ波を導入するアンテナにおける光路長の変化により計測結果に誤差を生ずるのを防止可能にした極低温流体の密度計測装置を提供することを課題としている。
【０００９】
【課題を解決するための手段】
本発明は、前記課題を解決するため、マイクロ波を極低温流体内に導入する導波管の側面に、極低温流体を同導波管内に流入させるための開口を設けたホーンアンテナを使用した極低温流体の密度計測装置を提供する。
【００１０】
マイクロ波導波管の断面形状は周波数によって規格化されているが、マイクロ波反射面でない２つの面にはマイクロ波が漏れない程度の開口部を設けることが可能であり、本発明の装置では使用するマイクロ波導波管の側面に対し、前記したように極低温流体を流入させる為の適当数の開口を設ける。
【００１１】
従って、導波管内にはその開口から固体水素を含むスラッシュ水素のような極低温流体が流入し、導波管内に常に安定したマイクロ波光路長が形成され、従来のもののようにマイクロ波光路長が変って測定値に誤差を生ずることがない。
【００１２】
更にまた、本発明は、前記課題を解決するため、マイクロ波を極低温流体中に導入する導波管の内部に誘電率が既知の誘電体を充填した極低温流体の密度計測装置を提供する。
このように、導波管内に既知の誘電体を充填しておいたものを使用すると、計測時に導波管内には極低温流体が侵入せず、導波管の誘電率は常に一定となる。
【００１３】
従って、本発明の極低温流体の密度計測装置によれば導波管内への極低温流体の侵入の良否により誘電率測定に光路長変化に基づく誤差を生ずるという事がない。
【００１４】
【発明の実施の形態】
以下、図１及び図２に示した実施の形態に基づいて本発明による極低温流体の密度計測装置について具体的に説明する。なお、以下の実施形態では、極低温流体としてスラッシュ水素を対象とした場合について説明する。
【００１５】
（第１実施形態）
まず図１に示した第１実施形態について説明する。
図１は、本第１実施形態による密度計測装置において使用するホーンアンテナ２付きの導波管１のみを示している。
導波管１の中をマイクロ波６は、対面する２枚のマイクロ波反射面３で反射を繰り返しながら導かれるが、この対面するマイクロ波反射面３と隣り合う２つの面４に対し、複数個の開口部５が設けられている。
【００１６】
設ける開口の大きさは、スラッシュ水素中の固体水素を通過させる大きさであって、かつ、マイクロ波が外に漏れない程度のものとし、その数は適宜選定してよい。このように、導波管１に開口部５を設けたものを用いることにより、スラッシュ水素の密度計測に際してホーンアンテナをスラッシュ水素中に浸漬したとき、導波管１内には開口５からスラッシュ水素が流入可能である。
従って、導波管内にはスラッシュ水素の液柱が安定的に形成され、従来のもののように導波管内にスラッシュ水素が流入しない場合が生じて測定誤差が出るという事態が回避される。
【００１７】
（第２実施形態）
次に、図２に示す第２実施形態について説明する。図２において、導波管１の中にはテフロン ( 登録商標 )７が充填されている。導波管１の先にはホーンアンテナ２が取付けられており、その他の構造は従来のホーンアンテナと同じである。
このように構成されたホーンアンテナを密度計測に当って、スラッシュ水素中に浸漬すると、導波管１内にはテフロン ( 登録商標 )７が充填されているのでスラッシュ水素は導波管１内に流入することがない。
【００１８】
導波管１内に充填したテフロン ( 登録商標 )の誘電率は既知であるから、計測された位相変化から充填テフロン ( 登録商標 )による位相変化を差引いてスラッシュ水素の誘電率を知ることができる。
この第２実施形態の計測装置によれば、従来のもののように、導波管１内にスラッシュ水素の流入程度にむらが生じて誘電率計測に誤差を生ずるという事態が回避される。
【００１９】
【発明の効果】
以上説明したように、本発明の極低温流体の密度計測装置では、マイクロ波を極低温流体内に導入する導波管の側面に、極低温流体を同導波管内に流入させるための開口を設けたホーンアンテナを使用する。
【００２０】
従って、本発明の密度計測装置で使用するホーンアンテナの導波管内には、その開口から固体を含む極低温流体が円滑に流入し、導波管内に常に安定したマイクロ波光路長が形成され、従来のもののようにマイクロ波光路長が変って測定値に誤差を生ずることがない。
【００２１】
また、マイクロ波を極低温流体中に導入する導波管の内部に誘電率が既知の誘電体を充填したホーンアンテナを使用した本発明の密度計測装置によると、計測時に導波管内に極低温流体が侵入せず、導波管の誘電率は常に一定となる。
【００２２】
以上のとおり、本発明の極低温流体の密度計測装置によれば導波管内への極低温流体の侵入の良否により誘電率測定に光路長変化に基づく誤差を生ずるという事がない。
【図面の簡単な説明】
【図１】本発明の第１実施形態による極低温流体の密度計測装置に用いられるホーンアンテナの構成を示す斜視図。
【図２】本発明の第２実施形態による極低温流体の密度計測装置に用いられるホーンアンテナの構成を示す斜視図。
【図３】従来の極低温流体の密度計測装置に用いられるホーンアンテナの構成を示す斜視図。
【符号の説明】
１ 導波管
２ ホーンアンテナ
３ マイクロ波反射面
４ 面３と隣り合う面
５ 開口部
６ マイクロ波
７ テフロン ( 登録商標 ) [0001]
BACKGROUND OF THE INVENTION
The present invention relates to a density measuring apparatus for measuring the density of a cryogenic fluid such as slush hydrogen (in the present invention, simply referred to as a cryogenic fluid) in which solid hydrogen and liquid hydrogen are mixed in a sherbet shape using a microwave. About.
[0002]
[Prior art]
Slush hydrogen, which is a mixture of solid hydrogen and liquid hydrogen in a sherbet, is attracting attention as a new fuel that is more advantageous than liquid hydrogen in terms of transportation and storage costs. Thus, when using a cryogenic fluid in which a solid and a liquid are mixed, for example, as space fuel, it is necessary to know the exact density.
[0003]
As a method of measuring the density of a cryogenic fluid such as slush hydrogen, a microwave is introduced into the cryogenic fluid from an antenna, and the microwave that has passed through the cryogenic fluid is received by another antenna, and the phase of the microwave in between There is a method of measuring the dielectric constant of the cryogenic fluid from the change and obtaining the density from the obtained dielectric constant.
[0004]
That is, by using the above method, the dielectric constant as an average value of the solid-liquid mixed phase state is obtained, and the solid-liquid mixing is obtained from the obtained dielectric constant and the dielectric constant of the solid single phase and the liquid single phase given as the physical property values. The ratio is calculated and the density is obtained.
Thus, the principle of measuring the dielectric constant of the cryogenic fluid from the phase change of the microwave during the introduction of the microwave into the cryogenic fluid from the antenna and receiving by another antenna is given by the following equation.
[0005]
[Expression 1]
In order to introduce a microwave into a cryogenic fluid or to receive a microwave that has passed through a cryogenic fluid, a waveguide 1 having a horn antenna 2 attached to the tip of a waveguide 1 as shown in FIG. 3 is conventionally used. It was. The microwave is guided from the inner surface of the waveguide as a microwave reflecting surface, exits from one horn antenna, enters from the other horn antenna, and is guided to the measuring instrument using the inner surface of the waveguide as a microwave reflecting surface.
[0007]
[Problems to be solved by the invention]
In the conventional apparatus for guiding the microwave into the cryogenic fluid using the waveguide and the horn antenna and measuring the density in this way, the waveguide is a relatively thin tube, so that the cryogenic fluid is contained inside. When the fluidity is poor due to the contained solid, the cryogenic fluid may not enter into the narrow waveguide. As described above, if the cryogenic fluid enters the waveguide in an uneven manner, the microwave optical path length L in the above formula changes, which causes an error in the measured dielectric constant. there were.
[0008]
The present invention provides a microwave density measuring device for measuring the density of the electrode by introducing a microwave into the cryogen to measure the dielectric constant of the cryogenic fluid, resulting the cryogenic fluid based on dielectric constant Another object of the present invention is to provide a cryogenic fluid density measuring apparatus capable of preventing an error in measurement results due to a change in optical path length in an antenna for introducing microwaves into a cryogenic fluid.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention uses a horn antenna having an opening for allowing a cryogenic fluid to flow into the waveguide on the side surface of the waveguide for introducing the microwave into the cryogenic fluid. A cryogenic fluid density measuring device is provided.
[0010]
Although the cross-sectional shape of the microwave waveguide is standardized by the frequency, it is possible to provide openings on the two surfaces that are not the microwave reflection surfaces so that the microwaves do not leak, and are used in the apparatus of the present invention. As described above, an appropriate number of openings for allowing the cryogenic fluid to flow in are provided on the side surface of the microwave waveguide.
[0011]
Therefore, a cryogenic fluid such as slush hydrogen containing solid hydrogen flows from the opening into the waveguide, and a stable microwave optical path length is always formed in the waveguide. Will not cause an error in the measured value.
[0012]
Furthermore, the present invention provides a cryogenic fluid density measuring apparatus in which a dielectric having a known dielectric constant is filled in a waveguide that introduces microwaves into a cryogenic fluid in order to solve the above-described problems. .
As described above, when a waveguide having a known dielectric filled therein is used, cryogenic fluid does not enter the waveguide during measurement, and the dielectric constant of the waveguide is always constant.
[0013]
Therefore, according to the cryogenic fluid density measuring apparatus of the present invention, an error based on the change in optical path length does not occur in the dielectric constant measurement due to the penetration of the cryogenic fluid into the waveguide.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the cryogenic fluid density measuring apparatus according to the present invention will be described in detail based on the embodiment shown in FIGS. In the following embodiment, a case where slush hydrogen is used as the cryogenic fluid will be described.
[0015]
(First embodiment)
First, the first embodiment shown in FIG. 1 will be described.
FIG. 1 shows only a waveguide 1 with a horn antenna 2 used in the density measuring apparatus according to the first embodiment.
The microwave 6 is guided through the waveguide 1 while being repeatedly reflected by the two microwave reflecting surfaces 3 facing each other. A plurality of microwaves 6 are adjacent to the two surfaces 4 adjacent to the facing microwave reflecting surface 3. Openings 5 are provided.
[0016]
The size of the opening to be provided is a size that allows solid hydrogen in slush hydrogen to pass therethrough and is such that microwaves do not leak to the outside, and the number thereof may be selected as appropriate. As described above, when the horn antenna is immersed in slush hydrogen when measuring the density of slush hydrogen by using the waveguide 1 having the opening 5, the slash hydrogen is introduced into the waveguide 1 from the opening 5. Can flow in.
Accordingly, a liquid column of slush hydrogen is stably formed in the waveguide, and a situation in which measurement error occurs due to a case where slush hydrogen does not flow into the waveguide as in the conventional case is avoided.
[0017]
(Second Embodiment)
Next, a second embodiment shown in FIG. 2 will be described. In FIG. 2, the waveguide 1 is filled with Teflon ( registered trademark ) 7. A horn antenna 2 is attached to the tip of the waveguide 1 and the other structure is the same as that of the conventional horn antenna.
When the horn antenna configured in this manner is immersed in slush hydrogen for density measurement, the waveguide 1 is filled with Teflon ( registered trademark ) 7, so the slash hydrogen is contained in the waveguide 1. There is no inflow.
[0018]
Since the dielectric constant of Teflon ( registered trademark ) filled in the waveguide 1 is known, the dielectric constant of slush hydrogen can be known by subtracting the phase change caused by the filled Teflon ( registered trademark ) from the measured phase change. .
According to the measurement apparatus of the second embodiment, unlike the conventional apparatus, a situation in which the slush hydrogen flows into the waveguide 1 is uneven and the dielectric constant measurement error is avoided.
[0019]
【The invention's effect】
As described above, in the cryogenic fluid density measuring apparatus according to the present invention, an opening for allowing the cryogenic fluid to flow into the waveguide is provided on the side surface of the waveguide for introducing the microwave into the cryogenic fluid. Use the horn antenna provided.
[0020]
Therefore, a cryogenic fluid containing a solid flows smoothly through the opening of the horn antenna used in the density measuring device of the present invention, and a stable microwave optical path length is always formed in the waveguide. There is no error in the measured value due to the change in the optical path length of the microwave unlike the conventional one.
[0021]
In addition, according to the density measuring apparatus of the present invention using a horn antenna filled with a dielectric having a known dielectric constant inside a waveguide for introducing microwaves into a cryogenic fluid, the waveguide is cryogenic in measurement. The fluid does not enter and the dielectric constant of the waveguide is always constant.
[0022]
As described above, according to the cryogenic fluid density measuring device of the present invention, there is no possibility that an error based on a change in optical path length is caused in permittivity measurement due to the penetration of the cryogenic fluid into the waveguide.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a horn antenna used in a cryogenic fluid density measuring apparatus according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a configuration of a horn antenna used in a cryogenic fluid density measuring apparatus according to a second embodiment of the present invention.
FIG. 3 is a perspective view showing a configuration of a horn antenna used in a conventional cryogenic fluid density measuring apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Waveguide 2 Horn antenna 3 Microwave reflective surface 4 Surface adjacent to surface 5 Opening 6
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18768698A JP3670847B2 (en) | 1998-07-02 | 1998-07-02 | Cryogenic fluid density measurement system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18768698A JP3670847B2 (en) | 1998-07-02 | 1998-07-02 | Cryogenic fluid density measurement system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000019132A JP2000019132A (en) | 2000-01-21 |
| JP3670847B2 true JP3670847B2 (en) | 2005-07-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18768698A Expired - Fee Related JP3670847B2 (en) | 1998-07-02 | 1998-07-02 | Cryogenic fluid density measurement system |
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| Country | Link |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107240782A (en) * | 2016-03-28 | 2017-10-10 | 克洛纳测量技术有限公司 | The induction element of antenna and the method for manufacturing such induction element |
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| KR101174403B1 (en) * | 2010-01-28 | 2012-08-17 | 한국전기연구원 | Spectroscopy Analysis Method and Apparatus for Spectroscopy and Imaging using Waveguide with Antenna |
| NO331262B1 (en) * | 2010-04-12 | 2011-11-14 | Kongsberg Maritime As | Method and apparatus for measuring the density of a liquid |
| CN107192635B (en) * | 2017-06-14 | 2019-06-07 | 中国科学院遥感与数字地球研究所 | The method and system of nondestructive measurement density of wood |
| US20230236005A1 (en) * | 2020-04-22 | 2023-07-27 | Nippon Telegraph And Telephone Corporation | Permittivity measuring device and thickness measuring device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107240782A (en) * | 2016-03-28 | 2017-10-10 | 克洛纳测量技术有限公司 | The induction element of antenna and the method for manufacturing such induction element |
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| JP2000019132A (en) | 2000-01-21 |
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