Solar drying is another main form of solar thermal utilization. There are generally two drying methods: one is direct suction type, also known as open type; the other is indirect absorption type, also called convection drying type. The former is the traditional sun exposure, which requires direct sunlight and a large area of drying platform, and in the process of direct exposure, the dried objects are prone to local overheating and environmental pollution. The latter needs to be equipped with corresponding solar air collectors to generate a large flow of hot air, and force the hot air to penetrate into the dried material for dehydration and drying. From the perspective of the development of various countries, the indirect absorption type, that is, the natural or forced circulation convective drying method, is mainly used in industrial and agricultural production. The key to adopting convection drying is to solve the design and manufacture of high-efficiency hot air heat collection system, as well as the coordination and matching of solar drying device and storage building, scientific management, information collection and supervision and control.
Using air and liquid fluid as working medium, relying entirely on indirect heating by natural circulation, convection drying, and at the same time, long-term safe storage and preservation of the dried items, the technology development and production application of the two-in-one silo-type solar drying device ‘s report.
Using the two most common natural resources of air and water as working fluids, through the organic complementary application of their natural circulation heat conduction mechanism; and the mutual bridging and unification of the two functions of drying and storage; The new process of solar vertical drying process with completely different furnace drying process is applied as the main heat exchange method of the equipment due to the use of convective heat transfer mechanism of different working fluids. Power-driven new silo-type solar drying process.
This dual working medium natural circulation silo solar dryer can realize the control of indirect heating and convection drying through adjustable indirect heating and convection drying without consuming auxiliary energy and mechanical power in the process of dehydration drying and long-term safe storage. High-efficiency heating and dehydration of the dried material; it can also maintain the dry environment inside the storage device through temperature adjustment and dehumidification, and natural ventilation; and prevent insects, birds, rodents, dust pollution and other protective measures: achieve energy saving, emission reduction, low carbon, Reduce production management costs and ensure the safety, hygiene and long-term preservation of warehoused goods. The equipment is generally suitable for rural households, or industrial and agricultural mass production applications.
The so-called dual-mode natural circulation pod solar dryer is actually a solar water heater that transforms the inner tank of the vertical thermal insulation circulating hot water storage tank into a convection circulating solar dryer with a central heat storage exchange system: water tank thermal insulation The layer is the dried material in the dryer container; and the space between the metal of the water tank and the outer shell constitutes the hot chimney cylinder with the function of natural circulation ventilation and dehumidification. Therefore, regardless of spring, summer, autumn and winter, or wind, frost, rain and snow, there is a dynamic balance of heat exchange between the heat storage system centered on the tank liner and the dried material in the long water drop-shaped metal screen container, as well as the existence of the heat exchange phenomenon in the tank. The natural convection ventilation mechanism of hot chimney is not based on people’s subjective will, but is a physical phenomenon that exists objectively. Once this kind of system enters the running state, without the need of auxiliary energy or human intervention, it can run safely for a long time indefinitely, and there will be no so-called downtime or equipment failure at any time. It can be considered that the silo-type dual-substance solar dryer is a new generation of solar drying device with development prospects and a wide range of applications.
The invention can form a series of products according to the needs: it can be manufactured as small as a household hybrid dryer with an area of 2m²~4m² that can process or store two or three hundred kilograms of fresh heat at a time, and it can also be designed and manufactured into a large-scale dryer with a processing capacity of several tons. It is a large and medium-sized solar drying device specially used for industrial, agricultural production, or storage inventory. Compared with the existing drying devices such as drying stoves, ovens, box-type, drum-type, tunnel-type, belt-type and fluidized-bed-type, the system structure of the invention is also different in that the latter Generally, the drying process is carried out in a horizontal process or a frame-type system structure of a baking room; therefore, the land occupation area is large, and the energy consumption is large; the drying process must also be continuously turned over and forced ventilation, so the labor intensity is also very high. Big. The invention adopts the vertical drying process, and one device can complete the whole process from dehydration and drying to long-term safe storage; moreover, in principle, no auxiliary energy and extra power are needed. During the drying process, there is no large-flow cargo turnover handling, which saves labor, trouble, and consumption, and does not occupy indoor construction area. When the dehydration and drying are completed and transferred to conventional storage, it is only necessary to turn off or remove the solar (water, air) collector; switch the central heat exchange circulating water tank to the central (normal temperature or water cooling) temperature adjustment system; By opening or closing the natural ventilation and temperature adjustment of the hot chimney and the moisture-removing tubular air inlet of the system, the flow rate of the (cold and hot air) in the silo can be effectively regulated, so as to achieve natural temperature adjustment and ventilation without consuming auxiliary energy. Dehumidification, maintaining the low temperature and dry environment of the system, and realizing the purpose of long-term safe storage and preservation of the dried objects. The system can also effectively solve the contradiction between seasonal production and long-term safe storage and storage, and improve the utilization rate of equipment. The solar air collector and solar hot water collector group of the system can be used as other heating, thermal insulation, hot water supply systems or air heating systems after the dryer is converted into a normal storage state.
The social and economic significance of the invention lies in that the product technology has a wide range of practical applications: not only can it be applied to large-scale industrial and agricultural production; moreover, it can also be applied to thousands of rural households for dehydration and drying of agricultural and sideline native products, and non-staple food processing. Dehydration drying and long-term safe storage of household cereals, corn, beans, grains, and peanuts, walnuts, and nuts. In the new era of global energy-saving, emission-reduction and low-carbon economic development, the promotion and application of this achievement will expand a new field of solar thermal utilization and open up a new market space for application technology.