Parallel Plate Instrument for Measuring the Thermal Conductivity of Fluids and Solid Materials
For the determination of the thermal conductivity various measuring instruments are available. These are usually constructed for special materials. The usability of such instruments for different materials is reduced and/or not possible. In general, there are only limited possibilities for the measurement of the thermal conductivity of different media with only one apparatus.
The determination of the thermal conductivity with the parallel plate principle surely represents the method with the longest tradition. However, the long measuring time typical for steady-state methods and the insufficient measuring accuracy in spite of complex corrections are the main reasons for the fact that parallel plate instruments are hardly used as standard technology so far. Nevertheless, the method offers remarkable advantages such as the simple geometrical configuration. The planar form of the measuring volume allows measurements not only for fluids and bulk materials, but also for solid bodies. With the heating plate arranged at the top, measuring errors by free convection are avoided. Heat losses at the boundaries of the balanced heating plate can be minimized by a geometry optimization of the instrument. Also the interchange of heat between the surfaces of the heating and cooling plates by radiation, which can make up a considerable portion of the effectively measured thermal conductivity, could to be minimized and considered for data evaluation. Exact adjustment and determination of the temperatures, the geometrical parameters of the measuring volume, and the heating power for the heating plate allow absolute measurements of the thermal conductivity for many kinds of materials with an accuracy of better than 5%. By automation of the measuring routine, also the measurement time remains in reasonable dimensions.
In this work, the technical implementation of a parallel plate instrument minimizing the above problems is presented. The measuring accuracy of the equipment is evaluated by comparison of experimental and literature data for reference fluids. Measurements for different materials demonstrate the applicability of the developed instrument in scientific and industrial applications. Furthermore, thermal conductivity data for ionic liquids measured with the new apparatus were used for the development of a simple prediction method of this thermo physical property for this special type of working fluids.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Automated parallel plate instrument; heat transfer; thermal conductivity; thermal conductivity of fluids; thermal conductivity of solid; radiation correction; convection influence; measurement accuracy; ionic liquids
Institute / chair: Technische Fakultät der Universität Erlangen-Nürnberg
Technical consultant for expert services: Prof. Dr.-Ing. A. Leipertz (Betreuer), Prof. Dr.-Ing. S. Will, Prof. Dr.-Ing. A. Fröba
Publication year: 2011
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
About the PhD Dissertation Data Base
In cooperation with the Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK), we provide free access to current dissertations in the field of plastics technology.