Optimal Design Research On Microwave Oven Used For Making The Caramel Pigment Based On The HFSS Simulation Technology

The caramel pigment is a kind of natural artificial pigment, which is widely used in these industries like food, medicine, condiment, beverage, etc, occupied 90% of the total sales volume of food pigment. The traditional manufacture methods of the caramel pigment are ordinary pressure and high-pressure. However, the temperature of the former is hard to control and its quality is unsteady so that it isn't suitable for applying to large-scale industrial production, while the technology of the latter is complex; the production period is long; the equipment manufacture is expensive and the safety performance needs high requirement.To making up these shortages, the microwave method emerges as the times required. Actually, this new technology is paid higher attention, developed and applied in many fields for its quick heating, high efficiency and convenient operation. Besides, microwave method also can shorten the period of caramel pigment production, reduce costs and make product safe and healthy. But during the operation of caramel pigment production in the existing microwave oven, there are still some problems such as the uneven heating, lower energy efficiency, debased caramel pigment, etc. Therefore, directing at those issues, this study will focus on the optimal design research on microwave oven used for making the caramel pigment based on the HFSS simulation technology.Owing to the complexity of the interaction between microwave and material, during the microwave heating, it is difficult for online testing and calculating precisely the distribution of the electromagnetic wave of the cavity as well as the temperature of the inner material. Hence, most of the enterprises adopt the new designed microwave under the method of"design—sample processing - experiment - adjustment". But this method has its own shortages, such as, the ambiguous directivity, a large quantity of the samples, high cost of the research and development, lower efficiency and long period. In order to make progress, this study tries to introduce the new microwave oven used for making caramel pigment produced under the combined methods of VC programming and HFSS simulation optimizing. This new kind of microwave oven can not only shorten the development period, lessen the cost, but also reduce the energy consumption, improve microwave energy utilization and caramel product quality. Therefore, the mainly work done in this study is as follows: (1) The main factors influenced the microwave acting on the sugar mixture to produce caramel pigment is analyzed firstly, that is, the depth of the microwave penetrating to the sugar mixture, the size of the microwave cavity structure and the waveguide matching position.(2) Based on the dielectric property of the sugar mixture, computational analysis should be done for the penetrating depth of microwave towards mixture of different moisture, from which the sugar mixture height suitable for the production of caramel pigment can be obtained.(3) According to requirements of the caramel making technology, the different cavity dimension of resonant characteristics index through the VC programming can be got to analyze and evaluate the modal number, degeneracy, model complementation, waveform factors, etc., as well as to ensure the cavity's optimum dimension within the prescribed size.(4) By means of establishing cavity electromagnetic field FEM mathematical model and applying HFSS simulation, voltage standing-wave ratio of the cavity under different waveguide position and the distribution of the electric field on the surface sugar mixture can be drawn, which would be analyzed deeply so as to make sure the waveguide's optimum matching position within the prescribed limits.(5) From experiment, it was obtained that the caramel pigment made in the microwave oven created by VC programming and HFSS simulation optimizing not only has the advantage of lower temperature gradient and the high energy efficiency, improving from 48% to 56%, but also owns the merits of high product quality, that is, the color ratio has reached 78359.4 EBC and haematochrome 5.18.