科研之友
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摘要
The results of experimental research determining the coefficient of thermal conductivity lambda of selected liquids have been presented in this article. During measurements, a "hot wire'' method was used, which belongs to the most interesting method because of its simplicity, easiness of realization, and precision. Platinum Pt500 sensor was used during measurements, which along with the measuring system creates precise temperature measuring converter with voltage output. Temperature analog, novel converter was developed individually for the needs of this experiment, connected to the computer measuring system that consists of multifunctional output of 14-bit converter A/C type NI USB-6009 produced by National Instruments together with interactive software for registration and measurements of voltage signals. Measurements were registered with the help of computer measuring system, with sampling time every 0.1 s. In this study, three methods of interpretation measurement data are proposed. Furthermore, for the needs of experiment, a computer program was written that enables fast calculation of values of thermal conductivity coefficients in different time intervals. The biggest challenge in "hot wire'' method is to find the time range (t(min)divided by t(max)) to estimate the thermal conductivity. The study attempts to find the proper range for six liquids with known thermal conductivity. Finally, authors proposed a general relation to estimate thermal conductivity of liquids based on the known parameters: density and specific heat.
- 出版日期2016-4
