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Study On Infrared Ceramics Material And Drying Mechanism For Grain Drying

Posted on:2009-11-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:H Y DongFull Text:PDF
GTID:1103360272976319Subject:Agricultural mechanization project
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Grain drying is one of the key links of the corn processing, it is significant influencing for quality of grain. With the development of the national economy and improvement of people's living standard, requirements the quality of grain becomes higher and higher, regardless of grain for edible or application of deep processing. In addition to through, improved technology of agricultural production and the way of reasonable management to improve the quality of grain, by using of reasonable measures of processing and storage to ensure quality of after harvesting the grains is not serious deterioration. Research in improving the quality of grain of drying; reduce the energy consumption of drying advanced techniques, which plays a crucial role in the development of the rural economy, agriculture and the national economy.Infrared radiation is a new type of grain drying technology of efficient, energy-saving, low pollution. Infrared radiation is a process of radiation objects to spread by the way of electromagnetic waves. When the infrared radiation exposure to a object, if the frequency of the incident infrared and objects of molecule is same, the molecular material will be shown on the strong infrared absorption, the energy of be absorbed will be transformed into the thermal movement, and increase the object temperature, effect of heating and drying. High emissivity infrared ceramics material has wide range of application as one of energy saving materials. Radiation characteristic of infrared ceramics directly related to energy saving effect and drying quality of drying device. So developing a kind of high emissivity infrared ceramics material has important significance.Corn is one of the major crops in northeast region of China. By taking corn as the research object, the goal is ensure corn quality after drying and improve machining efficiency. A high emissivity infrared ceramics material fitting for grain drying was developed and was applied grain-drying device. This technique can improve grain-drying efficiency and have important practical engineering value in reducing energy consumption. This paper mainly studies the following key technologies. 1. In this paper, we were selected Al2O3, SiO2 as main precursor, Fe2O3, CuO, Y2O3 as supplementary material and mullite-ferrite ceramics were produced by high-temperature sintering. Infrared emissivity was determined at 5~15μm wave band. Formula scheme of optimum mass fraction is obtained by orthogonal design.2. Mullite powder ceramics were sintered on corundum ceramics substrate by using sintering technique. This avoids using binder and improves material service life. Compared with XRD test map and infrared properties map of samples, this paper studies the higher infrared emissivity reason of ceramics material and infrared emissivity effect of different materials and madding technique.3. We made powder material that is fit for thermal spraying using composite ceramics material by milling technology and made composite ceramics material coating using plasma-spraying technology. The results show that using heating plate of coating drying efficiency rises 15%.4. By the concept of the water potential introduced, this paper analyzed infrared drying mechanism of corn, and thought that moisture content remove force come from the difference of water potential because of the temperature grad and moisture content grad. Moisture content migrates from inside of higher water potential corn pellet to the lower water potential pellet outside, boils away within an inch of the corn pellet outside and spill over the corn pellet surface. In the same condition, compared with having not far-infrared coating, drying efficiency is higher. This is because that infrared coating emission spectrum is fit for corn absorption spectrum, and it benefits corn inner moisture content faster moving forward surface. The result is that corn is not easy to appear surface hardening and crack. In addition, drying efficiency increases as the infrared plate distance short and heating power rises.5. Based on the theoretical analyses of water potential, the mathematical model of infrared drying has been developedresult was found after the model was analyzed. are undetermined eonstants and t 15 timeinterval.6 .Infrared drying exPerimentaldevce was modifieated based on exPerimental table for grain drying, with heating plate of ceramics material. The model for infrared drying that based on the theoretical is an average moisture content model of corn pellet. Verified the model simulation results by the testing data, the value of simulating average moisture content is as consistent as the trial value; the correlation coefficient is more than 0.98.In summary, using infrared ceramics material, which is suitable for grain can, improves grain drying efficiency greatly and having important practical function in reduce energy consumption and improve the grain quality. This research results provide a technology of practical value and have greater social and economic benefits. Meanwhile, the studies can rich basic theory of grain infrared drying. It has academic significance and practical engineering value.
Keywords/Search Tags:grain drying, infrared, composite ceramics, coating, water potential theoretical
PDF Full Text Request
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