Seite - 155 - in Adaptive and Intelligent Temperature Control of Microwave Heating Systems with Multiple Sources

5.3. ResultsofDifferentControlMethods Through numerous practical heating experiments, the main conclu- sioncanbeobtainedthatthecontrollabilityofHEPHAISTOSislargely determined by the heating setup. To be more specific, different heat- ing setups create different boundary conditions for different parts of the workpiece, which significantly affects the overall controllabil- ity. For example, for the setup shown in figure 5.1 with large sizes (1.2m×1m×2mm), it is inevitable tohavehotspots inthecentralpart of the workpiece and cold spots in the corners and edges. A typical heatingprocesscanbe illustratedbythefigures in 5.17. (a) t=5min. (b) t=10min. (c) t=15min. (d) t=20min. Figure5.17. Heating process ( from (a) to (d) ) with the setup of aluminum plate. That is mainly due to different thermal conduction impacts from the aluminum plate and the metal table below the aluminum plate. Dur- 155