We offer you an option solar drying, which does not consume electricity.
Many of us already use dryers to prepare food for the winter. It is much more environmentally friendly than freezing, since it lasts throughout the entire storage period of the food.
Modern dryers are very efficient and fast, but they also run on electricity.
Let's look at a simple compact drying that can be done at home. 
Here's the front view. The cover is made of polycarbonate sheet. There is a ledge at the bottom for water drainage. Bottom and back panel covered with black plastic 
This is a side view. Again, the side is covered with a protective layer of polycarbonate. Side panel height (61 cm), width (71 cm). The shelves are staggered so each shelf gets some direct sunlight.
Products on the top shelf tend to dry faster, so I often shuffle them to the top when upper layer dries out. I forgot to take a photo of the shelf, but they are mostly rectangular wooden structures with plastic mesh.
The shelves run on wooden runners and can be easily pulled out through the back door. 
Here's the back panel. It is (61 cm) high and (64 cm) wide. A ventilation opening 6 cm high is made in the rear wall and is covered with a mesh. 
The same opening is located at the bottom front under the polycarbonate sheet.
The essence of ventilation openings is very simple. During drying warm air rises and exits into the rear opening, and the cold one is drawn in from the front into the lower one. This creates good airflow for drying food.
The only problem I ever had was ants, but that was solved by having ditches around each leg that they couldn't climb. To do this, you can use inverted cans medium sizes that need to be placed under the legs. You can also use large containers of water.
The height of the legs is about 15 cm.
Hopefully this is enough to get you started on your own solar drying dehydrator. I like it and the products dry in it in 1-2 days and, most importantly, it uses free energy and reduces harmful effects on the planet.
You can dry almost anything in it: apples, pears, plums, strawberries, herbs and tea leaves, any vegetables and root vegetables. But, most importantly, this does not require electricity or money.
Someone will probably think - what a curiosity. In the meantime, many summer residents are faced with the issue of preserving berries and fruits grown on their plots. Of course, most of us make canned food. But there are cases when fruits or berries need to be dried for further storage. And here the dryer comes to our aid.
However, please note. If you ask the word “Dehydrator” in Russian on YouTube, you will be given a myriad of videos with a variety of electric and gas dryers. We are artificially pushed towards dependence on electricity and spending money on buying household appliances. But as soon as you ask the same word “Dehydrator” in English transcription, the English-language part of YouTube will give you dozens of videos with homemade structures solar dryer. You will be surprised how varied these designs are.
Unlike us, the entire Western world is actively trying to use endless solar energy. Residents of private houses make a variety of dryers, which they actively use.
Why do you need a dehydrator? You can dry almost anything in it. Apples, pears, plums, strawberries, herbs and tea leaves, any vegetables and root vegetables. The same strawberries or roots. Anything that can be cut into slices or folded into a small layer. But, most importantly, this does not require either electricity or money.
Let's see how a dehydrator works. We won't consider it very much complex designs or very primitive. Let's take a look at a classic dehydrator with a solar panel.
The frame of the dehydrator consists of bars. Usually a block of 50*40 mm or 40*40 mm is used. The framework is quite simple and does not require much knowledge to create. Its width and depth are chosen at the discretion of the master. Usually this is 500 - 600 mm, depending on your desire.
The height with the roof ridge is approximately 2 - 2.2 m. It makes no sense to do it higher; it will be inconvenient to maintain.
From the inside, slats for retractable mesh shelves are placed on the frame. The outside of the dehydrator can be lined with clapboard or plywood. Some are simply covered with black film. But in my opinion, it is better not to use polymers.
Mesh shelves are made from a 20*30 mm block and covered with any mesh you have.
A swing door is made at the back of the dehydrator. And on the front side at the very bottom they make a cut for solar panel.
It is also made without any fuss. This is an ordinary box covered with glass and painted black on the inside. The top and bottom of this box are drilled to allow air to pass through. The sun heats the panel through the glass and the air from it begins to rise.
Many craftsmen install tubes from ordinary beer cans with a drilled bottom inside the solar panel. They are glued together into tubes and also painted black. The air in such tubes heats up even faster and rises faster into the dryer.
There are also craftsmen who connect fans to the solar panel. This will speed up the movement of hot air, but requires electricity. Which turns a solar dehydrator into an electric air dehydrator with solar heating. I won’t say that this is bad, but you can’t leave such a dehydrator unattended. And besides, this requires costs both for the fans themselves and for electricity. Perhaps such a decision is justified if you have solar battery, which can be installed on the dehydrator. But you must admit, this is a slightly different design.
plot, then, as a rule, the problem arises of where to put the entire harvest. Of course, you can simply eat a lot of things during the season, and some can be preserved for the winter. But many more different fruits and vegetables have to be thrown away because there is nowhere to put them.
The best way to stock up for the winter is drying. This way, the maximum amount of vitamins is preserved in the products, and this process is much simpler than canning. In addition, dried fruits and vegetables take up little space and are not heavy.
Today we will look at how you can make a simple dryer that runs on... solar energy. This will be especially convenient for those who like to save money, or for those whose home has long been running on alternative energy, using wind or solar power. In addition, the construction of such a dryer will cost much less than buying an electrical appliance.
The basic principle of a solar dryer is to force hot air to circulate inside the device. The more actively it circulates and the hotter it is, the faster and better the food will dry. The air in the homemade product is heated due to special panel, which is painted black with heat-resistant paint. Cold air enters through the bottom, then is heated by the sun's heat, expands, and exits through the top of the dryer. Here it is important to correctly calculate the diameter of the inlet and outlet holes in order to obtain desired temperature and air speed.
Materials and tools for homemade work:
List of materials:
- square pipes;
- sheet metal;
- polycarbonate sheet;
- two hinges for the door and a locking mechanism;
- screws, self-tapping screws and more.
List of tools:
- welding;
- Bulgarian;
- drill;
- marker and tape measure;
- metal scissors;
- stationery knife;
- hacksaw.
Solar dryer manufacturing process:
Step one. We make a frame
It all starts with making the frame. The author used square pipes as the material. Everything is assembled using a grinder and welding. As for the sizes, you can choose any of them, depending on your needs and the availability of materials. The author was guided here by the dimensions of the polycarbonate sheet.
You can see in the photo what shape the dryer should be, but you can come up with your own.
Step two. Making a door
The author is making a metal door; here you will need sheet metal and square pipes. First you need to cut four pieces square pipe and weld a rectangle out of it, the shape of which should fit the frame of the dryer. The door must fit tightly to the frame, since if gaps form, the efficiency of the device is reduced.
Well, in the end the frame is covered with a sheet of metal. Here you can use self-tapping screws, screws with nuts, and so on. More steel sheet can be welded. The door is installed after the trim.
Step three. Covering the dryer
Before sheathing the dryer, you will need to make fastenings for the baking sheets. For such purposes you can use wooden blocks. They can be secured using self-tapping screws, or better yet, screws. In total, the author has space for 4 pallets.
Now you need to install such a thing as an absorber in the dryer. To make it you will need a sheet of metal. This sheet is placed at the very bottom of the dryer to heat the cold air there. The sheet must be painted black using heat-resistant paint.
As for the thickness of the metal, the thinner it is, the faster the dryer will start working when exposed to sunlight. It is better to use copper or aluminum as a material, as they conduct heat well, but steel will also work.
After installing the absorber, you can assemble external cladding. It can be attached using self-tapping screws or using welding. An important element dryer is the roof, it must be transparent, since it is through it that warm Sun rays. The roof can be made of glass, polycarbonate and other materials.
To prevent flies and other living creatures from flying into the dryer, the author attaches ventilation windows mask net.
That's all, the design is almost ready. Now you just need to secure the door. The ones you need will be here door hinges, a locking mechanism, and it would also be a good idea to attach a handle.
Step four. Making baking trays
The baking trays needed here are different from those in conventional ovens. They must allow air to pass through well so that food can dry. They are made very simply. To make them you will need a metal mesh, as well as a wooden beam.
First, you will need to make frames from timber. Well, then these frames are simply covered with mesh. To make it easy to install and remove the trays, the screws on the sides are not completely screwed in, and the tray is held on to them.
Step five. Testing the dryer
First of all, the dryer must be installed correctly. It should be such a place that there is a maximum amount of sun during the day. The sun's rays will shine through the cover, so the unit is oriented accordingly.
The choice of drying method is determined by the scale of production, climatic features of the area, type of material to be dried and cost. extra energy. The supply of heat to the material from the drying agent can be carried out by convection or by radiation; accordingly, convective and radiation dryers are distinguished. In the first, the product comes into contact with air heated by solar energy, in the second, the product is directly irradiated by the Sun, the temperature in dryers of this type reaches 60... 75°C. Combined dryers can also be used, in which both types of heat exchange are involved, but convection predominates, and the installation consists of an air heater and a drying chamber with transparent walls.
Natural drying of agricultural products has been widely used for a long time, with products spread on the ground, hung under a canopy or placed on pallets. When drying unprotected agricultural products in air, large losses occur due to incomplete drying, contamination, mold, bird pecking, insect damage, and precipitation.
Application of solar installations of the type " hot box» increases drying efficiency and reduces product loss. The drying time is significantly reduced and the quality of the product is improved, including the preservation of vitamins. However, the utilization rate of solar dryers for Agriculture, as a rule, low. In some cases, they may only be used for a few weeks over the course of a year. And this, naturally, does not contribute to achieving high economic indicators of solar dryers. Currently, it is economically feasible to use solar dryers for drying hay. The situation is quite favorable when drying wood, fish, and when using solar dryers in laundries.
Rice. 1. Solar dryer with direct irradiation of wet material:
1 - translucent insulation; 2 - platform for material; 3 - wall; 4 - thermal insulation; 5, 7 - holes; 6 - foundation.
There are solar dryers with direct and indirect action of solar energy. In installations of the first type, solar energy is absorbed directly by the product itself and the black-painted inner walls of the chamber in which the material being dried is located. A solar dryer of this type is shown in Fig. 1. It has top translucent insulation, a perforated platform for placing the material to be dried, side walls (the southern wall is made of translucent material), thermal insulation with holes for air intake and a base. For removing humid air From the solar dryer, holes are provided in the upper part of the northern wall. Drying plants of the second type contain a solar air heater and a chamber or tunnel dryer. In a solar chamber dryer, air moves through a layer of material to be dried, placed on mesh trays, from bottom to top, while in a tunnel dryer, the material moves on a conveyor belt in one direction, and the air moves countercurrently in the opposite direction.
Rice. 2. Chamber solar dryer with film air heater:
1 - film air heater; 2 - air duct; 3 - drying chamber; 4 - grate; 5 - visor; NE and BB - fresh and humid air.
Let's look at examples of the design of chamber solar dryers. Simple dryer using polymer film can be manufactured in accordance with Fig. 2. It works on natural draft. The air is heated in a film solar air heater and enters through an air duct into the lower part of the drying chamber, where it is placed on perforated trays (grids, grates). wet material. Heated air moves in the drying chamber from bottom to top through the layer of material and is removed from the chamber through the gap between the top edge and the visor. The walls of the drying chamber can be thermally insulated or made of translucent material. A film air heater is made of a polymer film stretched over wire frame. The upper surface of the heater is made of transparent film, and the lower surface is made of black film (Fig. 3, a). It can also be made in the form of two cylindrical surfaces - the outer transparent and the inner black (Fig. 3, b).
Rice. 3. Film air heater made of transparent (1) and black (2) polymer film.
The forced-air solar chamber dryer is shown in Fig. 4. It includes:
- air heater;
- drying chamber;
- fan.
Rice. 4. Chamber solar dryer with fan and corrugated air heater absorber:
1 - air heater; 2 - drying chamber; 3 - fan; 4 - thermally insulated body; 5 - translucent insulation; 6 - absorber; 7 - air duct; 8 - support; 9 - visor.
The heat-insulated body of the air heater with translucent insulation contains a blackened radiation-absorbing surface made of corrugated metal. Hot air through a thermally insulated air duct enters the drying chamber with perforated trays for the material to be dried, which is installed on supports and covered with a canopy on top.
In Fig. Figure 5 shows another design of a solar dryer with natural blast, differing in the type of air heater. The galvanized iron casing with thermal insulation houses two sections of a matrix-type air manifold. The housing has an opening for outside air and translucent insulation. Solar energy is absorbed in a matrix consisting of 2 rows painted black metal mesh with steel wool between them. It can also be made from several layers of black mesh. The heated air enters the drying chamber, which has a tapering shape and a series of meshes on which the wet material is placed. To supply air under each layer of material, vertical partitions are provided in the chamber, forming the necessary air gaps. The top of the camera is covered with a visor.
Rice. 5. Solar dryer with porous air heater absorber:
1 - air heater body; 2 - glazing; 3 - porous radiation-absorbing nozzle; 4 - drying chamber; 5 - grid for material; 6 - partition; 7 - visor.
The described solar dryer has high efficiency. The collector efficiency reaches 75% due to high air flow, and pressure loss - up to 250 Pa. Payback period - up to 5 years.
Rice. 6. Film solar dryer:
1 - transparent polymer film; 2 - black film on the flooring to place the product; 3 - thermal insulation; 4 - side walls.
A simple and cheap solar dryer can be made of transparent and black polymer film, stabilized against ultraviolet radiation (Fig. 6). On wooden frame 0.1 m thick polyethylene film is stretched, and the bottom is black plastic film(0.1 mm), laid on a layer of husk 75 mm thick, serving as thermal insulation. Side walls covered with earth at the bottom, the length and width of the collector are respectively 30 and 4.6 m. Heated air enters a cylindrical chamber with a diameter of 1.5 and a height of 1.8 m, which houses 1.75 tons of agricultural product (grain) in several layers thick 150 mm each.
Another design of a highly efficient solar dryer for various agricultural products is shown in Fig. 7. The air collector is made of individual modules with an area of 5 m2, which, when assembled, form panels installed in an inclined position on the roof of the barn. Inside the barn there are:
- horizontal chute or vertical hopper for wet material;
- fan;
- air distribution chamber.
Rice. 7. Solar dryer with modular type air heater:
1 - air heater module; 2 - drying chute; 3 - fan; 4 - air distributor; 5 - air duct.
Air panels solar collector connected to the fan using an air duct. The radiation-absorbing surface of the air collector is a porous matrix that captures solar radiation and has an extremely developed contact surface for heating the air. Lateral and back wall galvanized iron casings have thermal insulation. Translucent insulation - made of special durable polymer material, UV resistant, high transmittance for solar radiation.
Typically, modules 4.2 m wide and 2.5 m long are connected in series. Two 14.5 m long panels are connected to a single fan that forces air through this solar collector. Thus, for a solar dryer with a solar collector surface area of 120 m2, one fan with a power of 3.5 kW is sufficient, the dryer capacity is 800 kg of raw or 400 kg of dried product per day with an average daily solar radiation flux density of 19 mJ/m2 per day. The grain is placed in a horizontal chute blown with heated air. Similar installations can be used for drying corn and other grains and tobacco leaves.
To dry grain in a ventilated horizontal chute or vertical bin, heated air can be used, the temperature of which is only 2...3°C (with a layer height of up to 4 m) or 5...15°C (in a layer with a height of up to 1. 5 m) above temperature environment. The limitation of the layer height is due to the danger of water vapor condensation in the upper part of the layer, especially on cloudy days with high humidity air.
The following methods can be used to dry green feed and hay:
- drying with hot air (300°C) or warm air (40...80°C);
- ventilation with slightly heated air (0...10°C);
- ventilation with unheated outside air and drying hay on the ground under natural conditions.
Energy consumption when drying hay using solar energy is less than when using a dryer on liquid fuel, and is approximately equal to the energy consumption when drying with unheated air. The system uses an air solar energy collector, which raises the air temperature by 20°C on a bright sunny day and by 1°C on a cloudy day. At the same time, the moisture content of the hay decreases by 5% on a cloudy day. An ordinary glazed solar collector or the roof of the building itself, under which the bottom of the solar collector is mounted and a fan circulates air, can be used as a solar energy collector.
Timber timber can be dried in a heat-insulated chamber with a volume of 65 m3, in which up to 10 m3 of material is placed on a trolley; Fans circulate air through closed loop; the air is heated in a collector with an area of 75 m 2.
Dried fruits and vegetables are a storehouse of vitamins and pectins. This means that if you stock up on them in the summer, you can enjoy all these gifts of nature in the winter. Of course you can buy fresh vegetables and fruit in the store, today this is not a problem, but a large number of summer residents are trying to hold out their harvest until winter by canning or drying it. So, let's look at several design options in which drying can be done. By the way, let’s add that a homemade dryer for fruits and vegetables is a reality.
General device design
It should be noted that today gardeners use three types of dryers, which are based on different principles drying.
- Using air flow movement. Basically, the device of this device It is a box, inside of which grids are laid one above the other, and chopped fruits or vegetables are placed on them. One or two holes are made on the side of the box into which fans are inserted. With their help, airflow occurs.
- Using the sun. This is a chamber in the form of a box, installed at an angle so that the sun's rays always fall on the pallets where fruits and vegetables are placed. The front part of the device is often covered with glass or mesh. Experts recommend not using a metal body in this type of dryer. It becomes very hot under the influence of the sun's rays and itself begins to emit a large thermal energy, which negatively affects the quality of dried fruits.
- Dryer with infrared heating element. In principle, this is all the same as the solar variety. Only instead of sun rays (free), ultraviolet rays are used here, which are emitted, for example, by a special film connected to a transformer. A very effective design that dries quickly and efficiently. But of all those described above, it is the most expensive. True, one of the advantages is the fact that the design of the dryer itself can be simplified to a minimum. There is no need for a drawer or chamber, you just need to install mesh shelves and direct the UV rays from the heating element onto them.
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Use of air flow movement for drying
Manufacturing rules
Making your own fruit dryer is easy. Any design that resembles a box is suitable for this. For example, it could be a cabinet from kitchen set or an element of a wardrobe, you can make it from a refrigerator or hob, or rather, from her oven. Or you can assemble a box from scrap materials: plywood, chipboard, fiberboard, and so on.
let's consider homemade dryer. To do this you will need four identical sheets, for example, plywood, wooden slats section 30x30 and 20x20 mm, self-tapping screws, mosquito net.
- First of all, the frame of the box is assembled, for which it is necessary to connect 30x30 mm bars together into a structure that appearance will look exactly like a box.
- Then the frame is sheathed on three sides plywood sheets, which are pre-cut to fit the frame dimensions. You need to make holes on one of them (one above the other in vertical plane), in which fans will need to be installed. Installation can be carried out immediately or after assembling the entire structure.
- A fourth sheet is hung on the fourth side, in which a large number of holes with a diameter of 8-10 mm must first be made. The bigger, the better. Air driven by fans will be exhausted through them. By the way, the wall with fans is installed opposite the dryer door.
- Now we need to make the shelves. They are made from slats 20x20 mm, they should be rectangular and slightly less wide than the width of the drying equipment. This frame is stuffed with a mosquito net using a stapler and staples, you can also use adhesive composition. The number of shelves is determined by the height drying plant. There should be a distance of 10-15 cm between them.
- Therefore, taking this distance into account, guides made from the same 20x20 cm slats are installed inside the device (across). The shelves are placed on them.
- It should be noted that in this design there is no need to install a bottom and ceiling. Air from fans should be discharged not only through the perforated door. By the way, the latter is hung on hinges and there is no point in creating a tight connection to the frame of the box.
- Now we need to install the fans and connect them to the network alternating current, install shelves, having previously laid out chopped vegetables and fruits on them.
- Everything is ready, you can turn on the fans and wait for the laid out fruits to dry.
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Dryer manufacturing diagram
Assembling a solar dryer
Solar fruit dryer is energy efficient economical option. Electricity or other types of fuel are not used here. But there is one point in this design on which the efficiency of the process depends. This is the angle of inclination of the entire installation relative to the sun. That is, the sun's rays should cover the volume in which vegetables or fruits are located as much as possible.
Therefore, first, a regular box without a lid is assembled. This is the same wooden frame, trimmed with plywood or other sheets. Now this box must be installed at an angle, placing it on legs made from the same timber as the frame of the dryer. So that you understand what we mean we're talking about, look at the photo below.
Now we need to make the shelves. They are made in exactly the same way as in the case of the fan model. The main thing is to correctly install the guides under them in the drawer itself. The slats should be packed horizontally.
Basically, everything is ready. You can install shelves in the dryer and place chopped gifts of nature on them.
Several nuances of assembling a solar dryer.
- Holes must be made at the ends of the box so that air can pass through them. This is a kind of ventilation. The holes must be closed mosquito net to prevent insects from getting inside the unit.
- It is best to close the bottom of the device metal sheet. It will heat up and radiate its thermal energy, which will increase the efficiency of the drying process itself.
- All internal surfaces of the device must be painted black. It is clear that it attracts the sun's rays, and white repels them.
- The front part of the dryer must be covered with glass, or polycarbonate. The main thing is that the material used is transparent.
- Vegetables and fruits should be cut into small and not very thick pieces.
- If you are using a fan dryer, you do not need to turn on the air flow right away. It is necessary that the slices lie in the dryer for 2-3 days.
- Temperature is the main criterion correct process drying. 40-50C is optimal temperature, in which a maximum of vitamins and nutrients will remain in dried products. Therefore, some summer residents cover internal surfaces dryers thermal insulation material. This is especially true if the device is made from an old refrigerator.
- Shelves should only be mesh. Just in internal space Air must constantly circulate.
