OVERVIEW OF SOLAR DRYERS FOR DRYING LUMBER AND WOOD

Аннотация

This paper presents the results of using solar energy for drying lumber and wood in different countries: Canada, Russia, Poland, Finland, Bulgaria, and Syria. Also described is an innovative solar dryer for drying lumber developed at the Ferghana Polytechnic Institute at the Department of Ground Vehicles and Their Operation. KEYWORDS Solar dryer, lumber, fans, housing, drying process, moisture, thermal conductivity, sidewalls, air slots, air, absorber, transparent polyethylene film, chamber. INTRODUCTION placed in a heat-resistant moisture-proof material [15- 21]. Attempts to use solar energy for drying wood are being made in England, Canada, Poland, Germany, S. Nikolov, I. Drozdov, N. Terziev (Bulgaria) offer a China, France, Syria, Finland, Holland, Puerto Rico, two-zone drying chamber for drying wood, into which India, Taiwan, Uganda, Philippines, Ghana, Russia, 12 stacks (6 *1.2 *2.4 m) are loaded simultaneously Bulgaria, Pakistan. and other states [1-7]. with a capacity of 100 m3 of conditional material. The main element of the solar dryer is an air-type solar H. Oinas (Finland) gives the design of the dryer, which collector system. The upper southern transparent wall is a frame structure, in the sidewalls of which there is inclined vertically at a certain angle, and the are air slots. Above the material (shavings, straws) northern heat-insulating wall is located vertically. The installed transparent films that form a ventilation air rear sidewall is a panel sheathed in an aluminium space. At the bottom, under the drying object, there is sheet and coated in matt black. Conventionally, the an air duct through which air is supplied by a fan. In chamber is divided into two main and one zone sunny weather, transparent films roll up into tubes [8- between the stacks, which provided a low- 12]. temperature drying process to a moisture content close to or below the saturation limit of wood (15 ... A. B. Adamovich with employees (Russia) for drying 20%) from the simultaneous provision of high-quality materials of plant origin (fruits, vegetables, drying of the material in relation to internal stresses mushrooms, medicinal plants) offer an helio dryer, and plastic deformations due with a large amount of which includes an air heater and a mesh tray. The air evaporated water in the initial stages of drying. Air heater itself is a metal frame, which is covered with a transparent front and reflective rear and side films. An circulates between the curved panel and the solar collector system [22-29]. The aluminium trim on the absorber is located vertically in the middle of the solar front wall is perforated. Supply and exhaust frame itself. The collector-absorber of radiation is channels are located in the rear (northern) heat- made of a sheet of non-metallic heating element, insulated panel. Three axial fans are arranged Volume 02 Issue 04-2022 48 American Journal Of Applied Science And Technology (ISSN – 2771-2745) VOLUME 02 ISSUE 04 Pages: 47-57 SJIF IMPACT FACTOR (2022: 6. 108) OCLC – 1121105677 METADATA IF – 5.582 Publisher: Oscar Publishing Services Servi vertically in the stack space. There is a dampening V. Poskorobko (Poland) for the conditions of Cape pipe between the fans. The air circulation is two- Hajnówka (53 north latitude), when the average circular [30-37]. The second, main zone, is a weakly integral radiation is exactly 340 ... 419 kJ/cm2 per year, typical periodically operating drying chamber, in introduced a solar dryer. The heating device included which two stacks are located in pairs, where the wood a battery of solar collectors, a circulating water tank is dried to a moisture content of 8 ... 12%. for heating tubular heaters, and instrumentation. In the case when the solar collector system does not The chamber was provided with heat from two provide thermal power, then an additional installation independent systems, one of which was designed for of a steam or water heater system is provided. The water, heated by solar collectors, and the other for circulation in the last zone is carried out by 6 axial fans technically saturated steam. In 4 flat collectors, located horizontally [38-44]. The authors determine double glasses were installed above the absorber, that the use of solar energy in comparison with steam they let in solar radiation only in the direction of the convective dryers allows reducing fuel costs by 30% absorbers. Heated water up to 90 ℃. Circulated and provides, in combination (combinations) with between the solar battery. It should be noted that other types of technical fuel energy, year-round during full insolation between 10 and 15 hours the operation. water temperature reached 60 ... ℃. It is also noted here that an oak parquet frieze 25 mm thick at an air M. Al-Haddat (Syria) recommends a drying chamber temperature of 40 ... 45 ℃ reached a final moisture (38.5 *10, 2 *8.9 m) for drying, in which a tank with content of 22% in 12 days, and softwood lumber with water (135 m3) i