射频解冻数值模拟过程中不同方法所获初始电压值对样品温度的影响

Influences of Various Voltage by Different Obtaining Methods on Sample Temperature in Radio Frequency Thawing During Computer Simulation

针对射频解冻有限元模拟过程中所需极板电压难以由实验获取的问题,以冷冻牛肉为例,采用3种不同方式间接获取的输入电压(固定电压、实际阳极电压和公式推导电压),运用有限元模拟方法对3种尺寸(小:160 mm×102 mm×60 mm;中:220 mm×140 mm×60 mm;大:285 mm×190 mm×60 mm)的冷冻牛肉进行射频解冻,对比了模拟和实验获得加热速率和温度分布中电压选择的有效性。计算机模拟结果与实验结果对照表明,射频解冻能够均匀快速解冻冷冻牛肉样品,但存在少部分边角过热效应。对比三种输入电压模拟与实际试验验证得到的升温曲线和表面温度分布,结果表明阳极电压值数值与实际电压值较为接近,约为7.2～8kV,而推导电压值最高,约为9.2～10.7 kV。选用推导电压值的70%～80%作为模拟值时,所获得的样品升温速率和终温最为接近实验结果。该研究结果可为精确模拟射频解冻过程的输入参数的获取提供参考。

Because experiment could not obtain voltage between 2 electrode plates needed for radio RF thawing finite element in simulation, this paper used COMSOL Multiphysics software to study 3 different voltages ( fixed voltage, experimental anode voltage, and theoretically derived voltage) for simulating RF defrosting frozen beef samples in 3 sizes ( Little: 160 mm×102 mm×60 mm;Middle:220 mm×140 mm×60 mm;Large:285 mm×190 mm×60 mm), and then compared the effectiveness of the voltage selection for heating rate and temperature distribution between the simulated and actual results. The results showed that the experimental anode voltage and fixed voltage were close to each other in the range of 7.2~8 kV. But the theoretically derived voltage was the highest among all, about 9.2- 10.7 kV. The simulated result was mostly close to the experimental results, when selecting 70%~80% of the theoretically deducted value as the input voltage for computer simulation. This research conclusion could provide reference for obtaining input parameter of accurate simulate RF thawing process.