On-line Detection System Of Alcohol Degree Based On Perturbation Method

Liquor is very important consumer goods in people’s daily life, its main ingredient is ethanol, how to detect the alcoholic strength of wines rapidly with high precision, is one of the key factors to reduce costs and improve the product quality in the actual production process. In the real production, to ensure the stability of product concentration, operators need to sample site generally, then use alcohol hydrometer to measure the sample’s concentration substantially, sometimes,samples should be send to laboratory for more accuracy, using the expensive equipment such as gas chromatography to test, that is very inconvenience and the cost is also very high. In order to meet some distillery’s demands of measuring the alcoholic strength of wines fast and accurately, and real-time measurement, this paper developed a new type of on-line detection system to measure alcohol strength, which is based on microwave resonance characteristics.This design of alcohol detection system uses DSP technology, ADF4350 frequency synthesizer chip developed microwave source controlled by DSP controller, the source excites the microwave resonator cavity, the output signal of the resonator is detected by the detector, then sampled and processed by the DSP processor, and the concentration of alcohol is calculated by perturbation theory and dielectric properties of alcohol. The human-computer interaction of this system is realized by touch screen, so that the display looks easy to operate and very user-friendly. This thesis focuses on several studies carried out as the following aspects:1. Researched on the dielectric properties of different concentrations of alcohol at different frequencies. Fitted the standard curve of the dielectric properties of different concentrations of alcohol by Cole-Cole formula and logarithmic law, and tested it experimentally by the strip-line terminal short-circuit equipment, selected the resonant frequency of the perturbation cavity based on the standard curve and test results to develop the resonator.2. Designed and developed the hardware of the system. Developed a microwave resonant cavity for perturbation method have been used in this paper to test the alcohol strength. Perturbation method is generally used to measure low loss material, while the loss of alcohol and water is relatively large, and the dielectric constant of alcohol changed with frequency largely, so gave full consideration of alcohol dielectric properties and the convenience of practical application, Selected the cylindrical cavity’s resonance frequency is around 1.9GHz and designed a frequency source with 1-4GHz, and a detector works at 1-8GHz3. Compiled the software of detection systems based on DSP technology and designed touch screen interface. System software includes frequency source controlling program, AD sampling program, the communication program of DSP processor and the touch screen and so on. The system’s function is complete, and the touch screen interface is beautiful and simple with a good human-computer interaction effect.