果蔬物料变化对微波加热温度特性的影响

The effect of fruits and vegetables changes on the temperature characteristic during microwave heating

[目的]解决微波加热时,果蔬物料内会出现因局部温度过高而引起的焦化现象。[方法]建立介电特性随温度变化的电磁—热传导耦合模型,通过试验验证了模型的正确性。[结果]当形状为正方体、球体时,介电特性值较大的物料更容易在偏离物料中心处、中心处形成高温聚集区,高温聚集区的温度可比周围温度高10℃以上;若尺寸相同,介电特性越小的物料温度均匀性越高,介电常数减少24.8%可使温度均匀性提高43.8%。[结论]通过调节物料的介电特性和尺寸可有效控制物料温度分布的均匀性。

[Objective]This study aimed to solve coking scorch caused by excessive local temperature often occurs when microwave heating of fruit and vegetable materials.[Methods]A coupling model of electromagnetic-heat conduction with dielectric properties varying with temperature was established,and the correctness of the model was verified by experiments.[Results]When the shape is cube,materials with larger dielectric properties are more likely to form a high temperature accumulation zone far from the center,and when the shape is sphere,materials with larger dielectric properties are more likely to form a high temperature accumulation zone in the center.If the size is the same,the temperature uniformity of the material with smaller dielectric properties is higher,and the temperature uniformity is increased by 43.8%when the dielectric constant is reduced by 24.8%.[Conclusion]The temperature distribution uniformity of the material can be effectively controlled by adjusting the dielectric characteristics and size of the material.