An Experimental Microwave Drying Device With Power Output Been Adjusted Continuously

In early1950, the microwave drying technology began to develop, and the traditional drying method comparison, microwave drying speed, high efficiency, energy conversion rate, responsive capacity to control environmental pollution, covers an area of relatively small series of advantages. Microwave drying technology in just seven decades has been rapid development, due to the large industrial microwave drying device is very expensive and is mainly used in areas of industrial production. Therefore, most of the small microwave drying laboratory experimental apparatus used directly household microwave oven, but conventional domestic microwave energy control for intermittent switch, that is a constant transmit power of the magnetron microwave magnetron pass through the circuit to change the off time control to control the average output microwave power, the microwave power output of this method is imprecise, can not be continuously adjust the microwave output power can not guarantee the accuracy of automatic control of the drying process, have a greater impact on the drying process and drying quality, it is difficult to meet sciences experiments.In order to overcome the existing laboratory with small dry experimental device output power can only order style grading adjust the drying process does not automatically control the size of the output power of the magnetron, This text presents a small microwave drying device that satisfy the scientific experiments requirement, the microwave output power of the magnetron of the device can be continuous linear adjustable. The device can automated adjust output power and achieve the automatic control of the temperature by comparing the current and the preset temperature. Finally, the curve of the microwave output power of the device is obtained by the experiments. The text also confirms that the microwave output power of the device is continuous linear adjustable. And achieved good results in the actual drying experiments.This thesis rely on the National Natural Science Foundation of China (31060118) and Kunming University of Science and Technology Training Fund (No.2010-07) as well as Yunnan applied basic research fund project (2009ZC041M) A detailed analysis laboratory using traditional drying device, AC voltage regulator technology, to carry out a power continuously adjustable laboratory with small microwave drying device, designed the device’s main circuit, control circuit, such as drive circuit, an extremely important significance, and reached by the microcontroller programming the degree of automatic control.In this paper, the main research contents and results include:1. Makes a brief introduction to the concept of a microwave oven, microwave drying technology, microwave drying device, and explains the main content of this thesis the theoretical value, meaning and research.2. Introduces the working principle of the magnetron according to the working principle of the method to change the output power, and by the traditional household microwave oven power supply circuit as a basis for transformation in the circuit, established rehabilitation programs, gives block diagram of a main circuit.3. The basic scheme of the design of the regulator circuit, through the selection of the chopper circuit to achieve a change of the input voltage to the magnetron anode transformer. By comparison, the final one-way isolation integrated regulator AC voltage regulator module-oriented design program, the module is highly integrated, good stability, less emotional and complex harmonic adjustment tube off sensitive, to support the microcontroller output5V control signals, suitable for use with control chip is connected to the automated control of the apparatus become possible.4. Designed for dynamic control function of the experimental device subject a control circuit, the control circuit core component of the higher cost of selection on the market today AT89S51microcontroller, through DTH11temperature and humidity sensor digital acquisition humidity differential control and threshold comparator, complete automation and control functions. MCU display with1602LCD industrial character liquid crystal display, the DAC module TLC5615voltage-output chip, TI produced the microprocessor control program design ideas and program flow chart at last.5. Chapter design of the two experiments, a microwave transmitting power through the actual measurement of the magnetron, magnetron microwave transmitting power of the experimental apparatus used to authenticate with the anode voltage is continuously adjustable at the same time determine the device power regulation curve, and the error analysis, the final result consistent with topics designed to prove the feasibility of the experimental device designed; another experiment the actual drying comparative experiments of real materials, through the regulation curve the same material drying experiments using two different drying methods were drawn out of the water loss rate curves of the two materials, through comparative analysis, obtained the appropriate set of conclusions, thus proving the practicality of the experimental device designed.