Наукові вісті Національного технічного університету України "Київський політехнічний інститут" (Oct 2017)

Effect of the Convection Processes in Liquid on Thermal Conductivity Measurement Error by Direct Heating Thermistor Method

  • Gregory S. Tymchik,
  • Andrey M. Matvienko,
  • Mykola F. Tereschenko,
  • Sergey M. Matvienko

DOI
https://doi.org/10.20535/1810-0546.2017.5.107938
Journal volume & issue
no. 5
pp. 110 – 122

Abstract

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Background. The problems of choosing the optimal utensil diameter for the test liquids on the basis of the investigation of the convection phenomenon effect on the error when measuring the thermal conductivity of liquids by the method of direct heating of a thermistor are considered. Objective. The aim of the paper is to carry out experimental studies to determine the effect of the convection phenomenon on the error in measuring the thermal conductivity of liquids. Methods. An estimation of the thermistor heating temperature measuring accuracy by the method of direct heating of the thermistor for the test liquid in utensils of different diameters in determining the coefficient of thermal conductivity is carried out. Series of experimental research was carried out with the help of a device for measuring the liquids TPC in order to determine the optimum design of the probe and the thermostat, to select the optimum volume of the material research and to choose the materials of construction. Results. The results of experimental research with control liquids using the developed instrument based on the method of direct heating of the thermistor are presented, the thermistor heating temperature fluctuation values depending on the utensil diameter with the test liquid are determined. Conclusions. It is substantiated that when designing devices for measuring the TPC of liquids, it is necessary to take into account the individual properties of the liquids under investigation and to create the greatest possible uniform heating or cooling of the utensil with the test material. Also, it is necessary to use the minimum diameter utensils. It is recommended to use utensils for the test liquid with a diameter of up to 10 mm to reduce the error in measuring the liquid thermal conductivity.

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