Determination thermal and physical characteristics of liquids using pulse heating thermistor method
Abstract
This work addresses of the research thermal and physical characteristics of different liquids by non-destructive method. Proposed to determine the thermal conductivity of liquids used by pulse heating thermistor method. Considered calculation the unit to determine thermal and physical characteristics of liquids. Presented scheme thermistor probe design and block diagram the device for research. The results of experimental studies with control materials using established device based on pulse heating thermistor method showed high accuracy and efficiency of use to determine the thermal conductivity of liquids. Describes possibility of using proposed method for measuring the thermal conductivity of solid, conditional-solid and friable materials in biology and medicine.
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Introduction
Relevance of the research is that the thermal and physical characteristics of materials according to requests of scientific and industrial organizations, most interest are the thermal conductivity, heat capacity and thermal diffusivity. Thus, for through the presence of functional relationship between these characteristics and because the vast majority of stationary thermal processes defined methods, the greatest number of requests concerning heat. This is due to the fact that the thermal conductivity is sensitive to the chemical composition and structure of the material varies widely values.
The widespread introduction of new materials industry requires the development of instruments for research of thermal and physical characteristics (TPC), and in particular the thermal conductivity and thermal diffusivity, due to several reasons. First, the thermal conductivity is passport characteristic of existing and emerging new substances and materials, whose number is constantly growing. With thermal conductivity closely related issues saving energy and resources, calculations of thermal regimes of complex structures, optimization of manufacturing processes and many others. In addition, the thermal conductivity as structurally sensitive parameter is an effective tool in research [1].
Conclusion
1) By using the device, whose work is based on pulse heating thermistor method can be measure thermal conductivity λ in the range of 0.1 to 1.0 W/m*оK with an error not exceeding 3%. Also, using the device is the ability to measure thermal diffusivity α and the measurements obtained by the value of λ and α can calculate the thermal characteristics of experimental fluids - heat capacity Cρ and thermal activity ε.
2) The advantage of this method is use small volumes of liquids investigated by small size of thermistor probes and simultaneously test a large number of test liquid by increasing the number thermistor probes.
3) The probe affects thermal performance, availability containment chip thermistor (glass or epoxy), rejecting the electrical characteristics of various design and thermistor measuring probe.
4) If you are measuring static and dynamic errors. The statistical error is due to slow temperature variations experimental fluid contamination of surface thermistor probe formation on surface of balloons air stratification components of liquids research solutions and more. Reduction is achieved by statistical error correction values obtained based test liquid temperature, ensuring purity and homogeneity research probe liquids. Dynamic measurement errors that occur due to different kinds of vibrations measuring electrical signals in circuits, offset accumulation values and their subsequent statistical processing. To ensure the required accuracy of measurement TPC, advisable to increase the term measurement session and sessions measurement.
5) The proposed device can be modified with minimal time and material costs to significantly increase the number of thermistor probes. This allows both to test large number of experimental fluids that reduces testing time and measurement error.
6)This method can be used in biology to measure TPC biological materials, in medicine - to determine the immunological reactions in biological fluids, where limited volume of research material and requires a large number of investigated materials, food and oil industry.
7) The proposed method can be used to measure TPC solid, opportunistic solid, plastic, bulk materials. Thus to ensure reliable thermal contact with the research material enough to change the design thermistor probe.