Method for measuring densities based on circular magnetic levitation

Patent metadata

Field	Value
Publication number	US-11965904-B2
Application number	US-202117147721-A
Country	US
Kind code	B2
Filing date	Jan 13, 2021
Priority date	Jan 15, 2020
Publication date	Apr 23, 2024
Grant date	Apr 23, 2024

Abstract

A sample to be measured is placed in a medium solution between two circular magnets to ensure that the sample to be measured is levitated in a set circular area between the two circular magnets, and a levitation position of the sample to be measured in the magnetic field is measured. The density of the sample is calculated according to formula (I):ρs=ρm+χm-χsg⁢μ0⁢(Br⁢∂Bz∂r+Bz⁢∂Bz∂z).Compared to the prior art, the method of the present disclosure provides a novel method for measuring a density of a substance, in which the involved device is easy to operate and has low cost, and the measurement results are easy to observe and have high accuracy.

First claim

What is claimed is:

1. A method for measuring a density based on circular magnetic levitation, comprising:
placing a sample to be measured in a medium solution located between two circular magnets to ensure that the sample to be measured is levitated in a set circular area between the two circular magnets;
measuring a levitation position of the sample to be measured in a magnetic field; and
calculating the density of the sample to be measured according to formula (I):

ρ
s

=

ρ
m

+

χ
m

-

χ
s

g
⁢

μ
0

⁢

(

B
r

⁢

∂

B
z

∂
r

+

B
z

⁢

∂

B
z

∂
z

)

;

wherein:
ρ s is the density of the sample to be measured, g/cm 3 ;
ρ m is a density of the medium solution, g/cm 3 ;
χ s is a magnetic susceptibility of the sample to be measured, dimensionless;
χ m is a magnetic susceptibility of the medium solution, dimensionless;
g is a gravitational acceleration, m/s 2 ;
μ 0 is a vacuum permeability, N/A 2 ;
B r and B z are respectively a radial magnetic field intensity and an axial magnetic field intensity at the levitation position;
r is a levitation radius of the sample to be measured in the medium solution being a distance from a center line of the two circular magnets to the sample to be measured; and
z is a levitation height of the sample to be measured in the medium solution being a distance from an upper surface of a lower magnet to the sample to be measured; and

wherein a distance between the two circular magnets satisfies:
(1) a curve expressed by a formula

B
r

⁢

∂

B
r

∂
r

+

B
z

⁢

∂

B
r

∂
z

=
0

 does not completely coincide with a center line of the two circular magnets; and
(2) a gradient of the curve expressed by an expression

B
r

⁢

∂

B
r

∂
r

+

B
z

⁢

∂

B
r

∂
z

 in r direction is greater than 0.

2. The method of claim 1 , wherein the two circular magnets are arranged coaxially up and down; and like poles of the two circular magnets face each other; and the medium solution is arranged between the two circular magnets.

3. The method of claim 2 , wherein an outer radius of each of the two circular magnets is 20-40 mm; an inner radius of each of the two circular magnets is 10-30 mm; a height of each of the two circular magnets is 10-30 mm; a magnetic induction intensity of each of the two circular magnets is 0.08-0.2 T; and a distance between the two circular magnets is 30-50 mm.

4. The method of claim 1 , wherein the medium solution is a solution of manganese salt, iron salt, or gadolinium salt.

5. The method of claim 4 , wherein the medium solution is an alcoholic solution or an aqueous solution of manganese salt, iron salt, or gadolinium salt with a concentration of 0.5-5 mol/L.

6. The method of claim 1 , wherein an outer radius of each of the two circular magnets is 20-40 mm; an inner radius of each of the two circular magnets is 10-30 mm; a height of each of the two circular magnets is 10-30 mm; a magnetic induction intensity of each of the two circular magnets is 0.08-0.2 T; and a distance between the two circular magnets is 30-50 mm.

7. The method of claim 1 , wherein the sample to be measured is a spherical sample, an ellipsoidal sample, an oblate sample, a disc-shaped sample, a cylindrical sample, a biconical sample, a cube-shaped sample, or a rectangular parallelepiped sample with a square cross section.

8. The method of claim 1 , wherein the density of the sample to be measured is 0.8-1.5 g/cm 3 .

9. The method of claim 1 , wherein the mediu

Assignees

• Univ Zhejiang

Inventors

• Zhao Peng
• Zhang Chengqian
• Gu Fu
• Zhang Xuechun
• Xie Jun
• Fu Jianzhong

Classifications

• G01N9/08 Primary

  by measuring buoyant force of solid materials by weighing both in air and in a liquid · CPC title

• G01N9/12 Primary

  by observing the depth of immersion of the bodies, e.g. hydrometers · CPC title

• G01N9/18

  Special adaptations for indicating, recording, or control · CPC title