- 學位論文
聲磁式氧氣濃度量測與自動校準系統之整合
Integration of a magneto-acoustic oxygen measurement and calibration system
摘要
本研究目的是發展一台整合量測與自動校準功能之聲磁式氧氣濃度偵測儀。此儀器原理是利用氧氣分子的強順磁特性，使用交流磁場讓樣本氣室中的氧氣分子隨著磁場的強度變化，產生週期性的聚集與擴散，因而造成倍頻的氣壓波動訊號，其強度與氣室內氧氣的濃度成比例，再使用麥克風來量測此氣室內的聲壓訊號，且藉由諧振放大線路放大以提高氧氣濃度訊號檢測的訊雜比，同時為了簡化量測系統之架構與體積，以提升系統的可攜性，直接將市電源經過變壓器耦合至電磁線圈以產生所需之強交流磁場。此外，為能進行自動化的氧氣量測校準，透過資料介面系統遙控質量流量控制器與氣室充氣之電磁閥開關，調控校正用之氧氣濃度，所擷取的氧氣濃度訊號，經由所撰寫的一套監控及量測控制界面能夠即時顯示，以完成氧氣濃度偵測儀之校準及量測的整合。此氧氣濃度偵測儀校準0%~100%氧氣濃度結果經由分析後，可得到R2值為0.997，靈敏度為2.4 mV/%。
並列摘要
The purpose of this project is to develop an oxygen concentration measurement system and to integrate it with a calibration system. The measurement principle is based on the strong paramagnetic property of oxygen molecule. By applying a strong alternating magnetic field on the sample cuvette, the oxygen molecule in the cuvette periodically concentrate and relax following the change in the strength of magnetic field. A doubled frequency of acoustic wave is generated in the cuvette. Its strength is proportional to the concentration of oxygen in the sample cuvette. This acoustic signal is picked up by a microphone and amplified by a tuning amplifier to increase the signal to noise ratio. In order to simplify the system and reduce the size and weight of the instrument, the strong electromagnet is directly driven by the 60Hz power line coupled through a transformer. To calibrate this oxygen measurement instrument, an automatic calibration system was also constructed. A mass flow controller is remote controlled to mix and provide different concentration of oxygen. The purge of sample cuvette by known concentration of oxygen is also controlled by solenoids. The acoustic signal is acquired, analyzed, and shown on screen for real time monitoring. The calibration of oxygen concentration measurement, from 0% to 100%, shows an R2 value of 0.997 and a sensitivity of 2.4 mV/%.
參考文獻
延伸閱讀
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