Seite - 5 - in Adaptive and Intelligent Temperature Control of Microwave Heating Systems with Multiple Sources

1.1. DevelopmentofMicrowaveHeating Advantages Drawbacks Autoclave highqualityworkpiece expensive; slow Electron- beam highquality workpiece; low costs; short time very large temperature difference for thick workpieces Ultraviolet (UV) veryshort time special resinmatrix needed; relativelyhigh costs X-rays largepenetrationdepth longcuringtime; safety issues Microwave Heating short time; low costs; large penetrationdepth; highheating efficiency temperaturecontroland non-uniform distributionproblems Table1.1. Comparisonofdifferentcuringmethods (accordingto [BRS01]). [LLG14] and [KMS01], quality failures caused by the non-uniform temperature distribution have become the major problem associated withmicrowaveheatingapplications. It is easy to control a single temperature under microwave heating, by using a temperature sensor and adjusting the microwave power based on the feedback temperature value [SZ06]. Nevertheless, it is way more complicated and difficult to control the entire temperature distributionof theworkpiece. Because the temperaturedistribution is determined not only by the properties of the workpiece, but also by theelectromagnetic (EM)fielddistributionwithinthemicrowavecav- ity. The EM field and temperature distributions are governed jointly by two partial differential equations (PDEs) [BBBB95], which are the Maxwell’s equations [Mer98] and the forced heat transfer equation [Met96]. On the one hand, the EM field distribution influences the 5