Liquid thermophysical property device for measuring temperature at symmetrical points of parallel double-line heat source and measuring method

Abstract

A liquid thermophysical property device for measuring temperature at symmetrical points of parallel double-line heat sources comprises a first slender electric heater, a second slender electric heater and a temperature sensor, wherein the first slender electric heater and the second slender electric heater are arranged in parallel and are equal in size and heating power, and the temperature sensor is arranged at the plane-shaped center of the first electric heater and the second electric heater. The two electric heaters are respectively provided with two extraction electrodes, wherein the extraction electrode of the first electric heater is connected with the extraction electrode of the second electric heater through a conductor. According to the method for measuring the thermophysical property of the liquid by using the thermophysical property sensor, a theoretical solution of a transient heat conduction equation under the action of a parallel double-line heat source and an extreme point of a symmetrical point temperature rise rate are utilized, temperature rise and the temperature rise rate are measured, and the thermophysical property of the liquid is measured according to time and temperature rise corresponding to the extreme point of the temperature rise rate. And the thermal diffusion coefficient and the thermal conductivity are directly calculated.

Description

technical field [0001] The invention relates to a device and a method for measuring the thermal properties of liquids, in particular to a device and a method for simultaneously measuring the thermal conductivity and thermal diffusivity of liquids while simultaneously measuring the temperature of a symmetrical point of a parallel double-line heat source. Background technique [0002] Liquid thermal conductivity and thermal diffusivity are important thermophysical properties and are the key basic data for the design of fluid heat exchange equipment. The methods of measuring thermal conductivity and thermal diffusivity at the same time are based on the transient heat conduction theory. The temperature or temperature change rate on the characteristic point or surface, and then calculate the thermal conductivity and thermal diffusivity according to the analytical solution or numerical solution of the heat conduction equation under the boundary conditions. [0003] Theoretically,...

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Problems solved by technology

[0007] The main defect of the transient hot wire method is to avoid the initial temperature rise stage of the measurement, and the approximate solution can only be satisfied after a long enough time, which will lead to excessive temperature rise and cause the natural convection of the fluid, and in order to shorten the During the test time, the temperature measurement point should be as close as possible to the heat source. The common practice is to use the hot wire itself as a thermometer at the same time, for example, use an electrified platinum wire as the wire heat source, and use the relationship between the resistance and temperature of the platinum wire to measure the temperature. Theoretical assumption of a constant power hot wire that deviates from changes in heater resistance during the measurement

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