DIY fruit and vegetable dryer: solar, infrared, from improvised items

The most ancient way of preserving fruits and vegetables is drying. Initially, it was made only with the help of sunlight, but now special devices are used for this purpose - solar or infrared dryers. They can be purchased at the store, or you can make them yourself. How to do this, we will consider further.

Content:

  1. What kind of device is this?
  2. Bars Solar Dryer
  3. Infrared dryer with heating elements
  4. Homemade dryers from improvised items

What kind of device is this?

Modern dryers are presented in a wide variety, but mainly they consist of several tiers of mesh drawers located one above the other. The device is closed by a lid, in the middle of which there is an opening for the exit of moist air. The pallet is equipped with a simple electric motor. It heats the incoming air masses, which are then redirected to the working chamber and act on the ingredients.

It is written about how to choose a dryer for vegetables and fruits in an equipment store here.

In the blanks, metabolic processes are activated, which accelerate the process of their drying. During heating, moisture from the fruits evaporates, and their final moisture indicator averages 5-8%. To prevent a sharp impact of the open air flow on the fruits, it is recommended that they be cut and laid out in trays, and simply kept in the dryer after 3-4 days.

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In general, two conditions are required to dry products:

  • to create a warm temperature regime at which the evaporation of moisture from fruits and vegetables begins (about 40 degrees);
  • create ventilation through which moisture will be removed from the container in time.
Dryer for fruits and vegetables

To assemble a dryer of any type with your own hands, one must proceed from these criteria. Beginners can start with solar appliances, while more experienced ones can handle the assembly of infrared dryers.

Bars Solar Dryer

It is the most economical option, since the design works due to the heat of sunlight and does not require any additional energy sources. You can assemble such a dryer from a wooden cabinet, which will have sectional trays for fruits and vegetables. What you need to do for this, read on.

Assembly

To assemble the solar structure, you will need wooden bars of 50x50 mm in size, but their width and length can be changed based on your own needs. It should be borne in mind that the number of trays located inside will depend on the height of the structure.

You can make a wooden dryer according to the following instructions:

  1. Knock down the bars to get a contour of the future dryer. In general, three such circuits will be required, and one of them will be used as a door.
  2. Determine the angle of future shelves. The trays must be placed at an appropriate angle so that the rays warm up the workpieces when the cabinet is located at a right angle to the sun. You can determine the angle empirically, since it depends on the time of year and the territory of residence. To do this, install the frame in the sun and trace its shadow. When it is tilted, it is important to determine the moment when the shadows of the two contours converge. At this time, attach the level to the side wall and use a pencil to mark the location of future shelves.
  3. Sew the side and back walls with plywood or lining. In addition to the back wall, it is worth attaching a thin metal sheet, which will increase the heating of the dryer.
  4. Build ventilation units. In the upper and lower parts of the structure, plywood is to be beaten from the front and back parts, in which to make round holes of 8 pieces on each side to ensure the exit of wet fumes. Close the holes with a mosquito net to prevent insects from entering.
  5. Paint black inside the structure to create a greenhouse effect in the dryer, which will speed up the drying of fruits and vegetables.
  6. Set shelves. For the free circulation of air in the structure, mesh materials are required. For these purposes, it is best to use a mosquito net, which is fixed to the frame.
  7. Place the cabinet on long legs, which are fastened with the help of transverse wooden beams.
  8. Cover the front of the frame with transparent material through which sunlight can pass and affect the fruit. For these purposes, you can use transparent slate, cellular polycarbonate or glass. For even greater heating, tin cans of drinks can be preliminarily placed at the bottom of the cabinet.
  9. On top of the cabinet, close the roof with plywood or metal sheets, and then make a door to tightly close the structure. So, by simple manipulations, you can assemble a solar dryer.

For the best effect of sunlight on fruits and vegetables during drying, the structure should be elbowed to some surface. If not, you can use the pipes by attaching them to the sides of the dryer.

Operating principle

The assembled dryer operates as follows:

  1. The sun's rays penetrate the structure through a transparent coating and heat the back metal sheet.
  2. The temperature in the container rises and exceeds 40 degrees, and therefore the fruits gradually begin to dry out.
  3. Moisture, which comes from fruits and vegetables, is vented out through the ventilation windows, so that the products do not mold. So, ventilation needs to be given special attention so that cold air enters through the lower hole, is heated and discharged through the upper hole, also removing moisture out.

Thus, natural air circulation is carried out, and the heating and ventilated effect is simultaneously. A similar model of the dryer allows you to provide all the necessary conditions for drying fruits and vegetables.

The drying process cannot be accelerated by increasing the temperature to 50 degrees or more, since this will lead to the destruction of large quantities of vitamins and pectins in the blanks, which will ultimately reduce their nutritional value.

In the following video, the home master demonstrates how to assemble a simple but productive dryer from wooden bars:

Infrared dryer with heating elements

This type of dryer emits infrared radiation of a certain wavelength, which is actively absorbed by the water contained in the products, but not absorbed by the fabric of the dried blanks. So, when moisture is removed under conditions of low temperature (40-60 degrees), vitamins and biologically active substances are stored in fruits and vegetables. In addition, they retain their natural color and aroma even after drying.

The device using infrared heating elements has the following characteristics:

  • the level of preservation of nutrients: 80-90%;
  • loss of vitamins: 5-15%;
  • reduction of blanks in volume: up to 3-4 times;
  • reduction in the mass of blanks: 4-8 times;
  • storage of products after drying: up to 2 years in an airtight container.

Heating element selection

To make such a dryer, you need an infrared heating element in the form of a flexible polyester film. It can be purchased on the radio market. The optimal characteristics of this element are as follows:

  • power consumption: 30 W;
  • supply voltage: 12 V;
  • temperature on the surface of infrared radiation: up to 65 degrees;
  • operating temperature range: from -40 to 50 degrees;
  • dimensions: 28x20 cm;
  • weight: up to 15 g;
  • Warranty period: 2 years from the date of purchase;
  • service life: 50 years.

Such a heating element will become the heart of an infrared dryer, which you can assemble yourself in several stages.

Assembly

Two lattice plastic boxes are used as the basis of the design. Their optimal length is 48 cm and a width of 29 cm. They have a convenient initial shape and are suitable for the dimensions of the heating elements. In addition, the boxes are made of plastic, so it’s convenient to work with them.

Having prepared the heating element and two drawers, you can start assembling the dryer:

  1. Trim part of the wall of one box, as this will allow to maintain the optimal distance from the surface of the heating element to the products inside the box. This distance can be from 7 to 10 cm. So, if the standard height of the sides was 11.5 cm, then after trimming it should be 7-10 cm. Also trim the corner supports of the drawer. The optimal length is 13.5 cm. The finished box will later be the main (bottom).
  2. Take the second box with a side height of 18 cm. Trim part of the wall, but do not touch the reference angles. Install on the main drawer to get a compact and lightweight frame.
  3. Prepare holder for infrared heating elements. To do this, you can use double-folded cardboard with a thickness of 6 mm, since it will provide greater rigidity. So, you need to cut three cardboard partitions along the contour of the box - upper, middle and lower.
  4. Take the usual food foil and glue the partitions as follows: the lower and upper - on the one hand, and the middle - on both. To attach the foil, you can use double-sided tape. The foil is used as a reflector because it helps direct the infrared rays created by the heating elements towards the products.
  5. Attach heating elements to the foil walls using double-sided tape. Do this as follows: attach 2 elements (4 in total) to the upper and lower septum, and 2 elements on each side (4 in total). In this case, you need to do all the conclusions of the heating elements in one direction, so that it is easier when connected. At this stage, the dryer assembly is completed, so it remains to connect.

It should be noted that on the partitions there may be free areas that could not be covered with heating elements. You should not worry about this, because there is a small spread of infrared rays, therefore they will heat the entire area of ​​the trays, that is, all the workpieces will be dried under a similar effect.

Connection

When assembling the dryer, only 8 heating elements were used. Each of them consumes 30 watts, so the total power of the device is 240 watts. In addition, it must be borne in mind that a voltage of 12 V is required for drying. To ensure it, it is advisable to use a step-down transformer 220/12 V and a power of 250 watts. Here are its characteristics:

  • manufacturer: Feron;
  • input voltage: 230 V;
  • output voltage: 12 V;
  • power: 250 W;
  • Dimensions: 84x29x42 mm.

Particular attention must be paid to the connection step, because in case of an incorrect or unreliable connection the device simply will not work, and failure of the heating elements can lead to a breakdown of the lowering transformer.

In order to correctly perform all the work, initially you need to understand the connection diagram of the heating elements. Since they must work in parallel, two elements can be connected as follows:

Connection diagram for heating elements

In the case of a dryer, 8 heating elements will need to be connected, with each polarity connected to a transformer. Therefore, the exact design of a 240 W dryer will look like this:

Dryer Connection Diagram

Having figured out the circuit, you can proceed directly to the connection of the wires together. In this case, it is worth using flat connectors “mother-father”, since with their help you can make a high-quality connection without the ability to solder, only using pliers and electrical tape. In addition, with such a connection, you can later turn off one of the heating partitions so that only one box works. This is convenient if you want to dry some foods.

Connection works are carried out in the following order:

  1. Connect the ends of the wires to each other, using the above diagram, and secure with a male connector on the heating elements.
  2. In addition, fasten with electrical tape of different colors to prevent confusion when connecting the mother-to-father connector with a transformer. In general, electrical tape will help prevent moisture from entering the connections.
  3. Connect on the transformer with 4 connectors for each polarity. To do this, use 4 wires of different colors, which will facilitate the connection process. You need to act carefully when connecting the transformer to the cable, which will be included in the 220 V.
  4. The design is ready, so it remains only to assemble the entire system. To do this, you need to insert the partitions into the frame: the top - on the top box with the heating element down, the middle - between the drawers, the bottom - under the second box, the heating element up.
  5. Turn on the transformer.

Check

To check a home-made dryer, you can use a thermal imager, because it will allow you to clearly see how the device works in the infrared spectrum. If the connection is made correctly, on the right you can see the operation of the heating elements 12 V. At the same time, it will be seen in the photographs that they create infrared radiation over the entire surface of the dryer, which is what is required for drying fruits and vegetables.

With the help of a thermal imager, it will also be possible to determine how much the whole structure heats up. Normally, the cardboard reflector will heat up to 34 degrees. This will mean that the main part of the infrared rays is directed in the right direction, that is, to the products. In the very center, the structure can heat up to 45 degrees. If you bring your hands to a running dryer, you can feel the pleasant warmth. In this case, there should not be any unpleasant aromas.

In order to increase the efficiency of the construction, it is possible to install a foam layer 2-3 cm thick on top and bottom of the dryer in order to direct infrared rays more than 80-90% towards the workpieces.

Homemade dryers from improvised items

You can assemble an electric dryer from old household appliances. We consider the various options below.

Homemade Fruit Dryer

Air grill

A number of simple manipulations are required to turn an aerogrill of any modification into a dryer. The instruction is as follows:

  1. Remove a baking sheet from the stove on which to spread vegetables, fruits, berries or mushrooms.
  2. Remove the lamp cover and fan from the air grill.
  3. Take the high grid from the kit to the baking sheet and install it exactly in the middle of the baking sheet, while it should rest firmly on steel, and not swing.
  4. Place the air grill cover on the grid and connect to the outlet.
  5. Open the handle to block the inclusion.
  6. Place the baking sheet with the air grill lid on the floor, stool or table. In this case, it is important to monitor safety in order to prevent fire. Keep curtains, pets, and children away.
  7. Run the grill according to the instructions at a low temperature, and care must be taken, since the heat will be quite strong.
  8. Set the timer for the makeshift dryer for 60 minutes. At the signal of the workpiece, mix, and after 20 minutes turn it on again. Continue until food is completely dry.

Fridge

If available old refrigerator and don’t know where to put it, then it can be easily turned into a dryer using the following instructions:

  1. Remove the freezer and compressor from the refrigerator. In such devices, as a rule, a double-glazed window is used as a heater. When removing it, you must act carefully, after putting on tight clothes and rubber gloves.
  2. In the lower and upper part of the refrigerator, make windows through which air flows will enter the structure, and then exit.
  3. Lock the door using a regular hook. If you bend it slightly and make a notch on it, when you close the door, it will fit as tightly as possible to the refrigerator, ensuring a tight closure of the case.
  4. To establish a fine-mesh mesh of metal as the bottom.

Grill grates

A primitive appliance can be assembled with a grill. Act in this order:

  1. Remove wire handles from the grate.
  1. On the grid, fix the fan, which is equipped with an engine. A similar element can be obtained from old technology or make it yourself. If there is no fan, two incandescent lamps with a power of 150 watts can be used as its replacement. It is worth considering that in the case of using lamps, drying will require a little longer.
  1. At the top of the drawer, install trays, which will be affected by the flow of air from the fan.

Heating film

It is used for installing underfloor heating. On its basis, you can make a simple and economical dryer.

The following materials will be required:

  • heating film measuring 50x100 cm and a power of 110 W;
  • electric wire with plug and switch;
  • insulation kit.

Masters with experience recommend using bitumen insulation, which is used for installing infrared floors. On top of this material, it is worth laying PVC insulation, which can be purchased at points of sale of the heating film. In general, the assembly of the dryer is as follows:

  1. Connect the wire to the heating tape, using 2 clamps, eyelets and terminal - rings.
  2. Connect the wires using a soldering iron. In the process of soldering, it is worthwhile to place a metal bar under the film in order to prevent its overheating.

After connecting the wires, you can get a dryer, the temperature of which can reach 58 degrees, which is quite enough for drying the products. A similar device is rolled up, so it is easy to store or transport. In cold seasons, it can also be used as a heater.

The following video provides step-by-step instructions for assembling an electric dryer from improvised means:

Each home craftsman can assemble a productive dryer for vegetables and fruits with his own hands, and for this you can use the most affordable materials and tools. There are many ways to assemble such a device, so everyone can choose the option that suits them.

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