Fast and economical drying of agricultural materials and maintaining their good quality has always been an important subject for us to study. Generally, the drying method of agricultural products is time-consuming and slow, and the negative temperature gradient is formed from the surface to the inside, which is not conducive to water evaporation. At the same time, the first drying of the surface layer of conventional drying will hinder the diffusion of internal water. Moreover, hot air drying consumes a large amount of gas or fuel, which not only pollutes the environment, but also has a negative impact on the nutritional value of agricultural products. The microwave drying equipment is different from hot air and other drying methods. The grain directly warms up after absorbing microwave to form a smaller positive temperature gradient, which is conducive to the diffusion of internal moisture and greatly accelerates drying speed. It is a new technology worthy of in-depth study.
Professor M ujumdar, chairman of IDS, pointed out that since 1990, the price of dry energy has remained important, but it is no longer the most critical factor for drying research. It is now driven by the demand for new products and processes. At the same time, it is pointed out that hot air drying is not an environmentally friendly operation nowadays. Carbon dioxide produced by fossil fuel combustion is the main component of the so-called “green room effect”.
Based on these considerations, the general objective of current drying is “to remove liquids (usually water) at the fastest speed and to minimize adverse effects on the product; not to damage the environment and to invest the lowest funds and operating costs”.
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