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Method and system for measuring heat conductivity coefficient of micro liquid

A technology of thermal conductivity and trace liquid, applied in the direction of thermal conductivity of materials, thermal development of materials, etc., can solve the problems of difficult to measure thermal conductivity of conductive liquids, expensive measuring devices, complex measuring models, etc., to achieve fast measurement speed, good adjustment effect, The effect of low operation difficulty

Pending Publication Date: 2022-04-01
TONGJI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The transient hot wire method (THW) has high precision and small error, and is suitable for various fluids, but requires a large number of liquid samples, the cycle is relatively long, and the thermal conductivity of conductive liquids is difficult to measure
The laser flash method (LF) can measure small-volume liquid samples and can measure conductive liquids, but it is difficult to measure samples with low thermal conductivity
Photon spectroscopy (PCS) can measure high-temperature and high-pressure liquids, and can measure conductive liquids, but the measurement model is complicated and the measurement device is expensive

Method used

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  • Method and system for measuring heat conductivity coefficient of micro liquid
  • Method and system for measuring heat conductivity coefficient of micro liquid
  • Method and system for measuring heat conductivity coefficient of micro liquid

Examples

Experimental program
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Embodiment 1

[0063] A method for measuring thermal conductivity of a trace liquid, comprising the following steps:

[0064] Double-sided metallization is performed on the dielectric film with known parameters, and a free surface of the dielectric film is closely attached to the semi-infinite liquid to be measured;

[0065] External DC voltages are connected on both sides of the dielectric film so that there is a uniformly distributed electric field inside the dielectric film, and laser pulses are applied to the other free surface of the dielectric film to collect the displacement current generated by the dielectric film-semi-infinite thickness liquid under the action of the laser pulse, which is recorded as Experimental displacement current;

[0066] Combining the parameters of the dielectric film and the actual model structure to establish a heat transfer simulation model, the simulation model is used to calculate the temperature distribution change in the dielectric film;

[0067] Take ...

Embodiment 2

[0116] A measurement system for the thermal conductivity of a trace liquid, comprising:

[0117] The holding device is used to place the dielectric film 3 and the liquid 4 to be measured. The dielectric film 3 is a dielectric film 3 with known parameters and metallized treatment. The liquid 4 is placed in the holding device and a free surface of the dielectric film 3 Closely attached to the liquid 4 to be measured; one free surface of the dielectric film 3 is in close contact with the liquid 4 to be measured, and the other free surface receives the laser pulse 5;

[0118] measuring devices such as figure 2 As shown, it includes a voltage unit, a laser unit and an acquisition unit. The voltage unit is used to externally connect a DC voltage on both sides of the dielectric film 3 so that there is a uniformly distributed electric field inside the dielectric film 3. The laser unit is used to control the other free surface of the dielectric film 3. The laser pulse 5 is applied, a...

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Abstract

The invention relates to a method and a system for measuring the heat conductivity coefficient of a micro liquid, which are characterized in that a uniformly distributed electric field is applied to a metallized dielectric film, one side of the dielectric film is thermally excited by laser pulses, and the other side is in close contact with the liquid with semi-infinite thickness; collecting an experimental displacement current generated by the dielectric film-semi-infinite thickness liquid under the action of the laser pulse; establishing a heat transfer simulation model by combining the parameters of the dielectric film and an actual model structure, and calculating a theoretical displacement current according to the temperature distribution change in the dielectric film; and extracting the characteristics of the theoretical displacement current and the experimental displacement current for comparison and fitting, taking the heat conductivity coefficient of the liquid as a unique unknown variable, adjusting the heat conductivity coefficient of the liquid in the simulation model by using an iterative algorithm to enable the fitting degree of the experimental curve and the simulation curve to be optimal, and taking the heat conductivity coefficient in the simulation model at the moment as a measurement result. Compared with the prior art, the method is wide in application range, high in accuracy, high in measurement speed and low in operation difficulty.

Description

technical field [0001] The invention relates to the technical field of thermal conductivity measurement, in particular to a method and system for measuring the thermal conductivity of trace liquids. Background technique [0002] The thermal conductivity of liquid is one of the most important thermophysical properties of liquid, and it is the basic parameter to quantify the heat transfer process and evaluate the thermal performance of materials. In fluid science, the thermal conductivity of liquids is an important heat transport property. Accurate and reliable liquid thermal conductivity data are conducive to accurate calculation and improvement of heat transfer efficiency of fluids in heat exchangers, and are very important for the design and development of working fluids with very efficient heat transfer characteristics. The accuracy of measured values ​​of thermal conductivity of liquid materials is crucial in industrial applications. Inaccurate thermal conductivity of li...

Claims

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Application Information

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IPC IPC(8): G01N25/20G01N25/18
CPCY02E30/30
Inventor 郑飞虎陈师杰
Owner TONGJI UNIV