Microcontroller-based multi-sensor apparatus for temperature control and thermal conductivity measurement
| Autor: | B. M. Taele, L Olumekor, C Kufazvinei, M. Gasseller, R. Mukaro |
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| Rok vydání: | 2003 |
| Předmět: |
Materials science
Temperature control business.industry Applied Mathematics Instrumentation System of measurement Electrical engineering Hardware_PERFORMANCEANDRELIABILITY Multiplexer Temperature measurement Thermal conductivity measurement Microcontroller Data acquisition Hardware_INTEGRATEDCIRCUITS business Engineering (miscellaneous) |
| Zdroj: | Measurement Science and Technology. 14:N45-N49 |
| ISSN: | 1361-6501 0957-0233 |
| DOI: | 10.1088/0957-0233/14/8/402 |
| Popis: | A microcontroller-based multi-sensor temperature measurement and control system that uses a steady-state one-dimensional heat-flow technique for absolute determination of thermal conductivity of a rigid poor conductor using the guarded hot-plate method is described. The objective of this project was to utilize the latest powerful, yet inexpensive, technological developments, sensors, data acquisition and control system, computer and application software, for research and teaching by example. The system uses an ST6220 microcontroller and LM335 temperature sensors for temperature measurement and control. The instrument interfaces to a computer via the serial port using a Turbo C++ programme. LM335Z silicon semiconductor temperature sensors located at different axial locations in the heat source were calibrated and used to measure temperature in the range from room temperature (about 293 K) to 373 K. A zero and span circuit was used in conjunction with an eight-to-one-line data multiplexer to scale the LM335 output signals to fit the 0?5.0 V full-scale input of the microcontroller's on-chip ADC and to sequentially measure temperature at the different locations. Temperature control is achieved by using software-generated pulse-width-modulated signals that control power to the heater. This article emphasizes the apparatus's instrumentation, the computerized data acquisition design, operation and demonstration of the system as a purposeful measurement system that could be easily adopted for use in the undergraduate laboratory. Measurements on a 10 mm thick sample of polyurethane foam at different temperature gradients gave a thermal conductivity of 0.026 ? 0.004?W?m?1?K?1. |
| Databáze: | OpenAIRE |
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