Experiments have shown that the dehumidifier accumulates heat in just 140 minutes of a sunny day, and then gives it away for almost 24 hours.
Photo Credit: Vladimir Alekhin.
Scientific Frontline: Extended "At a Glance" Summary: Ecological Hybrid Food Dryer
The Core Concept: The ecological hybrid dryer is an advanced agricultural dehumidification device designed specifically for high-latitude regions with cold but highly illuminated "northern" summers. It utilizes solar energy combined with a thermal-storage core to provide continuous, 24-hour food dehydration without relying on conventional electrical grids.
Key Distinction/Mechanism: Unlike traditional solar dryers that cease functioning after sunset or electric models that consume costly energy, this hybrid device relies on a "smart" block containing an organic, phase-changing material (a paraffin-like substance). During daylight hours, the material melts to accumulate solar heat like a battery; at night, it freezes, releasing the stored thermal energy back into the drying chamber to maintain a stable, continuous drying temperature.
Major Frameworks/Components:
- Solar Collection Unit: Captures and utilizes available sunlight during extended high-latitude summer days.
- Thermal Accumulator (Phase-Changing Material): The core module filled with organic material that shifts between liquid and solid states to absorb, store, and distribute heat over a 24-hour cycle.
- Modular Architecture: The dryer is composed of interchangeable modules, allowing the system to be scaled and customized based on geographical latitude, seasonal solar radiation, and specific user needs.
Branch of Science: Thermodynamics, Materials Science, Agricultural Engineering, and Environmental Science.
Future Application: The technology is primed for immediate deployment in regions such as the Russian Urals, Siberia, Scandinavia, Canada, Alaska, and Northern China. It will be utilized for preserving vital crops—including vegetables, fruits, mushrooms, berries, herbs, and grains—ensuring food safety in cold climates. Researchers are currently negotiating with Chinese manufacturing partners for large-scale commercial production.
Why It Matters: This development provides a highly economical and energy-efficient solution to a critical geographic limitation in global agriculture. By maintaining stable internal temperatures, the dryer prevents crop spoilage, reduces drying times (e.g., accelerating mushroom dehydration by five hours), and yields substantial financial benefits, saving an estimated $77 annually in electricity costs per unit with a payback period of less than one month.
The device distributes heat around the clock, which optimizes the drying time of products
Russian and Chinese specialists from Ural Federal University have developed a hybrid dryer that is relevant for areas with a "northern" summer (high-latitude regions of Russia, northern Europe, northern China). The device works 24 hours: during the day it accumulates sunlight and accumulates heat, and at night it continues to dry foods thanks to a "smart" block – a phase-changing material. The cost of such a dryer is low due to the use of inexpensive components, the developers explain, and the payback period is less than a month. The researchers published a description of the new model and economic indicators in the journal International Communications in Heat and Mass Transfer.
"We live in a region where snow lies for half a year, and the sun is shining, but even in summer it does not warm much. At the same time, in summer, the days are long. That is, these are conditions in which there is no heat in winter, and in summer there is a lot of light, but there is no constant heat. Therefore, it is extremely difficult to dry crops outdoors or use solar dryers, and the use of electric analogues is expensive and economically unprofitable at high electricity prices. For such conditions, which, by the way, are relevant not only for the Russian Urals or Siberia, but also for Scandinavia, Canada, Alaska, and Northern China, we have developed a hybrid dryer adapted for the northern summer," says Vladimir Alekhin, Head of the Department of CAD Systems in Civil Engineering at UrFU.
The device contains a special unit with organic material (a paraffin-like substance). During the day, when the sun is shining, it melts, accumulating heat like a battery. At night, the material freezes and releases the stored energy back into the drying chamber. According to the developers, thanks to this, the dryer can work around the clock, using the accumulated heat even after sunset.
Such an air dryer can be used not only for drying vegetables or fruits, but also mushrooms, berries, herbs, and grains. These products are very important for regions with a cold climate, where food safety issues are more acute than, for example, in low-latitude regions.
"Experiments have shown that the dehumidifier accumulates heat in just 140 minutes of a sunny day, and then gives it away for almost 24 hours. Due to this, the temperature inside the unit is stable: during the day it does not overheat not to over-dry the products, and at night it does not decrease much. This approach allows you to reduce the drying time of products in comparison with a conventional solar dryer, and significantly save energy. For example, the drying time of mushrooms is reduced by five hours," says Yue Huang, a co-author of the development, a PhD student at the Department of CAD Systems in Civil Engineering.
The savings on electricity alone on one device will amount to about $77 per year. The payback period for such a device is less than a month. The Ural air dryer consists of modules, which, on the one hand, simplifies its assembly, and on the other hand, allows it to be customized to the needs of users, seasonal light radiation and geographical latitudes by changing the number of modules and rebuilding them.
There are analogues in the world, the researchers add, but these are mainly electric or solar dryers, which are either more expensive to use or take more time and are less productive to dry products.
The scientists plan to improve the efficiency of the device by increasing the thermal insulation properties of the thermal accumulator. In addition, scientists are searching for and negotiating with Chinese potential partners for further implementation of the device in production.
Funding: It should be noted that the Chinese Scholarship Council supported the work of Chinese PhD students.
Published in journal: International Communications in Heat and Mass Transfer
Authors: Wentao Hu, Yue Huang, and Vladimir N. Alekhin
Source/Credit: Ural Federal University | Delfina Zakharova
Reference Number: ms032326_01
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