Do-it-yourself dryer for vegetables and fruits. Refrigerator dryer

A homemade dryer for vegetables and fruits made from standard purchased parts will be no worse than an industrial one.

Homemade drying chamber

Before you start making a dryer for vegetables and fruits, familiarize yourself with the main requirements for drying. You can dry any fruits, vegetables and fruits that contain moisture:

• berries;
• mushrooms;
• apples;
• fish.

The drying principle is simple and long known. Under the influence of temperature, moisture is removed from apples, vegetables, berries and fruits. Therefore, a constant temperature of 50 to 60°C must be maintained in the dryer body while moisture is removed. For juicy fruits, a drying mode of one hour at a temperature of 60°C and subsequent hours from 50 to 55°C is provided. We'll look at how to make an electric dryer in this article.

What types of dryers are there?

There can be many reasons for making your own dryers of different volumes and power for vegetables and fruits: you are not satisfied with the performance, high price, high energy intensity, and others.

There are three options for making do-it-yourself dryers for vegetables, fish or fruits:

• electric;
• on wood;
• solar.

We will not consider other options for making homemade products, such as sublimation, UHF, infrared radiation, or using a vacuum due to the complexity of manufacturing.

Of the three options presented above, only electric can operate in automatic mode.

Wood and solar require human presence and adjustment can only be made using slide valves to regulate the inflow and removal of air.

Let's look at making a dryer with a capacity of 50 to 100 kg of wet product weight at home, based on the fact that the home craftsman plans to sell some of the dried products.

Energy intensity

A factory dryer with automation for processing dried apricots consumes about 1.6 kWh of electricity per 5 kg of raw product and dries for 36 hours.

Based on the average data, a handyman should take into account that a homemade dryer for processing 50 kilograms of a raw product such as apricot will consume 16 kW of electricity, and for 100 kg 32 kW. Using simple mathematical operations, you can find out the future costs of preparing 1 kilogram of fruit.

For household consumers, a maximum power consumption of 3 kW/h is provided. Accordingly, 16 kW can be taken from the line in 3 hours, and 32 kW in 6 hours of continuous operation. But you won’t be able to dry foods with a high water content in 3 or 6 hours.

Conclusions: in domestic conditions, building a dryer with a capacity of more than 50 kg of dry product is not problematic if there are no restrictions on energy consumption. Accordingly, if someone decides to build a 100 kg dryer, he will have to increase the drying time by 1.5 times. And then 100 kilograms of raw product will have to be dried for 3-4 days with an increase in electricity consumption to 32 kW.

Do-it-yourself electric dryer for fruits and vegetables

To do this, you need to make an electric dryer body, buy a fan, a heating element, a temperature sensor (thermostat), a time relay, and two chimney draft regulators.

Tips: Before you start building a dryer with a power consumption greater than 3 kW, ask your local power company about the maximum power they can provide you.

Fan

For our purposes, household smoke exhausters for boilers are best suited.

Smoke exhausters for domestic boilers

Their distinctive feature is that they can pass through air at temperatures up to 150°C without damaging the electric motor. An ordinary axial fan is not suitable for these purposes. It is not able to work at a temperature of 50°C for a long time. The diameter of smoke exhausters starts from 150 mm. An electric heating element with an open spiral must be placed in the pipe coming from the smoke exhauster.

Tips: you can buy a fan for snail-type boilers with a capacity of at least 50 times the volume of the drying chamber.

Electric heating element for dryer

For maximum heat extraction, the heating element must have an open coil. The power is calculated based on the permissible rated power for the house and is equal to 3 kW minus the power of the smoke exhaust fan and household appliances. If this norm is exceeded, the automation will work and turn off the lights in the house.

Electric heater with open coil

When choosing an electric heater, consider its dimensions. It must fit into a pipe that is connected to a smoke exhauster or fan that supplies air to the drying chamber.

Smooth thermostat

Thermostats with smooth temperature control from 0 to 300°C are a standard part of all household electric furnaces. It must be connected in series to the electrical circuit with heating elements and a fan. When the required temperature is reached, it will automatically turn off the heating and fan.

Household thermostat

You can use a thermocouple from ovens.

Where to buy a thermostat? There are several purchasing options:

• online store;
• the nearest repair shop for household appliances.

It is quite possible to purchase a thermostat at a flea market.

Time relay

In order to fully automate a homemade dryer, you need to buy an electronic two-channel time relay with weekly programming.

There are many options for designing and programming time relays and everyone can choose the right one for themselves.

By connecting a fan and heating element to the time relay, you can adjust its operation experimentally. To do this, you need to set the turn-on time of the heating element and fan.

Chimney draft regulator

Draft regulators are installed in stainless steel chimneys. This automatic device consists of a precisely fitted valve on an axle. To ensure that it is always closed or open, a small weight is installed on one side.

Install these two valves in the inlet and outlet openings of the dryer. When the fan is turned off, they will close the inlet and outlet of warm air under the weight of the load.

Traction regulator

The use of these valves will allow you to automate air intake and supply without the use of actuators and expensive controllers.

For particularly advanced handymen, we recommend purchasing a programmable controller. This equipment is more complex, but it allows you to automate all drying processes, connecting humidity sensors, temperature sensors, motors, gate valves and other actuators. They are widely used for lumber drying kilns.

When building a drying compartment, use the following materials for the frame:

• wooden slats;
• particle boards;
• fibreboards;
• oriented strand boards;

To insulate the drying chamber use:

• polystyrene foam boards;
• mineral wool;

Please note that the insulation is installed from the outside, not from the inside!

Homemade drying chamber

To fix the insulation, use:

• Titanium glue, mounting foam for polystyrene foam boards:
• plastic mushrooms for mineral wool.

Cover the insulation with fiberboard or seal it with self-adhesive aluminum foil. As a last resort, it can be plastered with synthetic mesh plaster. It is sold in construction stores for insulating houses.

If you do not have the necessary woodworking equipment to stiffen the frame, use metal corners for window frames.

Metal corners

It is better to connect a wooden frame with screws than nails.

Please note: to calculate the cross-section of wires, there is the following rule: for 1 kW you need 0.7 mm 2 cross-sectional area of ​​the wire. Thus, for a drying chamber with a rated power of 3 kW, the cross-section of the wires must be at least 2.5 mm 2.

Dried fruits

For safe operation, the metal parts of the dryer must be grounded.

When calculating the volume of the dryer, design a load of no more than 5 kg of wet product per pallet. If the pallets are placed at intervals of 10 cm, then the height of the chamber for 20 pallets will be 2 meters. In this case, there may be a problem with loading at high heights.

To combat mold and other diseases that occur in a humid and warm atmosphere, use an ultraviolet lamp.

For long-term storage and storage of food products for future use, various methods of processing them are used - drying, drying, smoking, salting. Often processing processes involve air drying. Some products that contain a lot of water are heat-treated, that is, dried at a fairly high temperature in the oven (melons, apples, some fruits). Many other foods are dried in the wind or sun (fruit, fish, poultry, ham, salted meat). An excellent alternative to such methods is a do-it-yourself mushroom dryer, which can also be used for preparing other products. Let's look at how convenient this device is and how you can assemble it with your own hands.

Harvesting difficulties

There are certain difficulties and inconveniences associated with the drying process. It often happens like this: you’ve just put the food out to dry, when suddenly the wind subsides or the sun disappears, or it even starts to rain, and all the work goes down the drain. But the greatest evil in the summer is associated with flies. They swarm around the exposed product and before you can blink an eye, they will lay their eggs in it. In this case, a DIY mushroom dryer will help.

Important! Flies are malicious carriers of infection. Contact of these insects with products is simply unacceptable. It is because of this that before hanging fish and meat preparations in the sun or wind, many wrap them in gauze; however, this does not always guarantee reliable isolation from flies, and in light winds it can complicate the drying process.

Particular difficulties arise for fishermen, because after a good catch and salting of the caught fish, it is simply unrealistic to wrap each fish in gauze to dry, and the likelihood of spoilage of the product by flies increases significantly, especially if the fish is layered. But still, there is a way out.

After many experiments, a wonderful solution was found - to make a dryer for mushrooms with your own hands, reminiscent in shape of matchboxes, or rather, the lid of this box, only several tens of times larger.

Dryer option No. 1

The design of the dryer and the principle of its operation are quite simple. To perform such a dryer, you should:

1. Make a frame in the form of a parallelepiped from slats.
2. Place it on edge (matchbox gray side down).
3. Cover both sides, as well as the bottom and top edges with solid material (oilcloth, roofing felt, cardboard, plywood). Moreover, the top edge will be a lid on hinges, like the lid of a piano.
4. Tighten the end edges with gauze or fine mesh.
5. Stretch wires along the side walls inside the dryer to hang food.
6. Inside, on one side, directly next to the gauze, install a tabletop room fan, and pass its current-carrying wire through the gauze, without leaving a free passage in it, and bring it out to the outlet.

Device Application

Food products should be placed on metal hooks and suspended from taut wires. After a complete check and all flies have been expelled, the lid is closed and the fan is turned on.

Important! The intense air flow created by the fan ensures fairly fast drying of food in compliance with sanitary requirements.

As a rule, the duration of drying in a mushroom dryer is determined experimentally. It will depend on the humidity of the surrounding air, its temperature, as well as on the size of the dried products, their moisture content and the required final moisture content.

• The dimensions of the dryer can be arbitrary and depend on the amount of product to be dried.
• In order to reduce energy consumption, it is recommended to use fans that have several operating modes, which will make it possible to change the ventilation mode in the dryer.
• You can install such a dryer almost anywhere: on the veranda, balcony, under a canopy or even on the street.
• It is better to load food in the evening or early in the morning, when there are no flies.
• It is better to first hang larger parts of food closer to the fan, and then they can be swapped.

Important! Many years of operation of dryers of this type made it possible to study their operation under different conditions. Remarkable results were obtained in drying fruits, churchkhela, low potatoes, dill, parsley, salted chickens and ducks, boiled sausages, hams, and dried mushrooms.

Dryer option No. 2

Let's look at another option, how to make a mushroom dryer with your own hands over a gas stove. So let's get started:

• For work we will need aluminum corners of various lengths and a wire mesh.
• First, measure the dimensions of the slab in order to create a dryer that can later be placed on its surface.
• Use a drill or electric drill to drill holes in the corners so that they can be secured with bolts and nuts.
• Now it comes to the grid on which the mushrooms will be placed. Cut it according to the dimensions of the slab and the frame itself, with a margin.

Important! A mesh made of bandage, gauze or plastic will not work, as it is dangerous to hold such materials over a fire.

• In order to secure the mesh to the frame, use the same aluminum corner, but smaller in size. It should turn out so that the mesh is laid on the platform from the frame from below, and pressed against the top by an overlay plate.
• Also attach the plate to the frame using screws through the pre-drilled holes.
• The height above the fire should be determined independently, approximately 60-70 cm (just saw off the legs to the required length).
• Place the mushrooms, turn on the gas and that’s it, the process has begun.

Important! Never leave gas unattended.

For long-term preservation and storage of food products for future use, they resort to various methods of processing them - salting, smoking, drying, drying, etc.

Most processing processes involve air drying. Some products containing a lot of water are heat-treated, that is, dried at high temperatures in the oven (some fruits, melons, etc.)
Most foods are dried in the sun or in the wind (salted meat, ham, poultry, fish, many fruits).

There are certain difficulties and inconveniences associated with the drying process. It often happens like this: you’ve just put the food out to dry, when suddenly the sun disappears or the wind subsides, or suddenly it starts to rain, and all the work goes down the drain. But the biggest evil in the summer is associated with flies. They swarm around the exposed product and can very quickly lay their eggs on it.

Flies are malicious carriers of infection. Contact of flies with products is unacceptable. That is why, before hanging meat and fish preparations out into the wind, some wrap them in gauze, but this does not always provide a reliable guarantee of isolation from flies, and in light winds it complicates the drying process.
Fishermen are experiencing particular difficulties.

After a successful catch and salting of the caught fish, it is unrealistic to wrap each fish in gauze to dry, and the likelihood of damage by flies is very high, especially if the fish is flaky.

But there is a way out.
After a series of experiments, an excellent solution was found.

We made a dryer with our own hands, reminiscent in shape of a matchbox, or rather, the lid of this box, but only several tens of times larger.

Operating principle of the dryer
The device and principle of operation are very simple. A frame in the form of a parallelepiped is made from slats and placed on an edge (matchbox with gray side down).

Both side faces, as well as the top and bottom edges, are covered with solid material (plywood, cardboard, roofing felt, oilcloth, etc.), and the top edge is a hinged lid (like the lid of a piano). The end faces are covered with fine mesh or gauze.

Inside the dryer, wires are stretched along the side walls to hang the product. On one side, inside, directly next to the gauze, a tabletop room fan is installed, and its current-carrying wire is passed through the gauze without leaving a free passage in it and brought out to the electrical outlet.

Food products are placed on metal hooks and suspended from tensioned wires. After carefully checking and expelling the flies, close the lid and turn on the fan.

The intense air flow created ensures fairly rapid drying of the product in compliance with sanitary requirements.
The drying time is determined experimentally. It depends on the ambient temperature, its humidity, as well as on the size of the product being dried, its moisture content and the required final moisture content.

Dimensions of a homemade dryer

The dimensions of the dryer are arbitrary and depend on the amount of product intended for drying. In order to save energy, it is advisable to use fans with several operating modes, which will also allow changing the ventilation mode in the dryer.

You can install the dryer on the balcony, on the veranda, in the barn, under a canopy, even in the open air. It is best to load food early in the morning or evening when there are no flies. It is advisable to first hang larger parts of products closer to the fan; later they can be swapped.

The long-term use of such a dryer made it possible to comprehensively study its operation under various conditions.

Excellent results were obtained from drying mushrooms, drying hams, boiled sausages, salted ducks and chickens, drying bunches of parsley, dill, low potatoes, churchkhela, fruits, marshmallows poured into baking trays, etc.

The useful work of a dryer when drying fish is simply difficult to overestimate.
I think many people will be interested in such a dryer, because the material used for its manufacture is virtually waste, the work is simple, a fan can be found in almost every home, electricity consumption is low, and the benefits are great.

Drawing of a homemade dryer

About drying apples...

Some readers claim that when apples are dried, neither vitamins nor beneficial microelements remain. Is it so? Yes, when drying, some things are destroyed, in particular, vitamin C. But most useful substances are preserved: potassium, calcium, phosphorus, iron, etc.

Apple chips

There is no cellar, so we dry the apples and make juice. At first I tried to store it in my grandmother’s way - in pillowcases, but this method did not suit us, since there is enough space either in the kitchen on a closet or in the room. In the kitchen there is constantly rising damp steam from the pots, and in the room there is a huge aquarium (200 liters). So I tried storing it in three-liter jars with lids.
For the experiment, half of the jars were covered with lids, half with newspaper. Both were perfectly preserved.
We opened the last jar at the end of summer (we have late varieties of apples). By the way, my daughters really like to nibble on dried apples, especially closer to spring, when vitamin deficiency sets in.
The apples were dried in an electric dryer at 500° for two days (turned off at night). They should become like chips - crispy, otherwise they will not keep. We wrap the jars in newspapers to protect them from sunlight.

Etc. harvest and it still serves faithfully. But its effectiveness always seemed insufficient to me, or rather, I wanted to make it even more effective. And then the other day an old refrigerator came into my hands. And I decided to make a drying cabinet out of it with forced ventilation, which will make the drying and drying process very fast, efficient and safe (in terms of getting rid of flies and wasps that tend to visit the processed products). They are known to not tolerate drafts.

First of all, you should empty the refrigerator body of all internal contents. We only need the body itself, usually metal. The only thing that should be left is the seal on the door.

When removing the refrigerator insulation, you should be careful, as it will most likely be glass wool. To prevent your hands from itching later, you should wear thick clothes and gloves, preferably disposable plastic or rubber ones, stretched over fabric ones. A respirator or just a scarf tied over your mouth and nose would also be a good idea.

The inner case - the “trough” - may be able to be used in some way in the future (for example, as a trolley body), although there are quite a lot of holes in it. And all we have left is a metal cabinet.

We install a regular exhaust fan into the niche where the refrigerator compressor used to be. True, in this case it will work as a pressure one. Generally speaking, I'm faced with a bit of a dilemma here. Formally, for drying it is better to use an exhaust fan, which will create a slight vacuum in the drying chamber. The lower the pressure, the faster the drying. But when installing an exhaust fan, you lose the ability to use a fan heater (which dramatically speeds up drying); you would have to install two of them or install a separate air heater.

Therefore, for now I settled on a blower fan with a diameter of 125 mm (capacity of about 180 cubic meters of air per hour, 18 W of power). Maybe later, when the “drying season” begins, I’ll try to switch it to the hood and compare the results. I specifically installed the fan off-center, so that later I could install either a second fan or install a fan heater (for example, from the dryer of an old washing machine).

I cut a hole in the roof of the refrigerator for a polypropylene pipe and glued it in with hot glue. It can be extended upward by installing a pipe 2 meters high or aluminum corrugation stretched up to 3 meters. It will be possible to install a Volpert-Grigorovich exhaust deflector at the top and then draft (and draft) will be achieved on their own, without a fan. This option will be useful for those who have problems with electricity in their dacha.

By the way, I painted the body of the refrigerator (as long as the spray can lasted) with matte black paint. Now, when the sun appears, the case heats up noticeably and even with the fan on, the air temperature (in the outlet pipe) is 5-8 degrees higher than the ambient temperature (measured with an electronic thermometer in a remote sensor).

To ensure that the refrigerator door was securely fixed, I attached a regular hook to it. The kind that is usually used on utility room doors or gates. I bent the tip of the hook a little and made a notch on it with a file. Now, when closed with a hook, the drying door is additionally attracted to the body, sealing, and fixed in this position. (I didn’t bother with different magnetic latches or clamps.). By the way, this solution to the problem of closing an old refrigerator (a real one) can be useful if it is leaking air under a worn door seal.

The insides of the dryer are “standard”. This is a shelving unit with retractable flat drawers. The bottom of the boxes is mesh, made of fine mesh. I made the shelves for the drawers from a narrow board. I had to make a cutout for the protruding edge of the refrigerator. For the drying process to be effective, the structure should be designed so that all the air passes exclusively through the bottom. Fastening the shelves directly to the walls of the refrigerator using self-tapping screws. Having marked the outside of the wall, I drilled holes in it, through which I secured the shelves with self-tapping screws with a head in the form of a press washer.

I must say that I was a little too clever here. You just had to cover the recess in the door with a sheet of plywood or plastic. Those. just make the door flat so that when closed it is flush with the front wall of the refrigerator. I decided to make curly shelves so that the drawers would almost rest against the door and air would flow through them. At the same time, the volume of the drying cabinet increased by the thickness of the door, and the work required an extra hour or two... In addition, certain difficulties arose with opening the door - the seal caught on the shelves. I had to file them down figuratively. But what's done is done. If anyone repeats the design, this should be taken into account.

Testing the refrigerator dryer completely satisfied me. A bunch of green dill wilted for winter storage in less than a day. I even cured some meat (for beer). Meat (beef, boiled and smoked), cut into long strips and rubbed with salt and pepper, dried to a “rubbery” state in just a few hours. It turned out something like biltong or sujuk. So, I’m ready for the mushroom and apple drying season!

So if you come across a case from an old refrigerator, spend half a day and you will have an excellent dryer for mushrooms, apples, berries, herbs and all sorts of medicinal herbs.

If you are a supporter of a healthy diet, and even more so if you are involved in growing healthy food yourself, a fruit and vegetable dehydrator will be your indispensable ally. I would like to offer you an option for a homemade electric cabinet for drying fruits, vegetables, herbs, berries and mushrooms from Ilya Tretnikov.

Materials and tools:
- plywood sheets for the body
- wooden slats
- self-tapping screws
- mosquito net
- drill
- furniture stapler
- heater
- foil
- power cord with plug
- electrical tape

Preparing the main elements

1. Wooden body for dryer
This could be an old bedside table or a wooden frame you put together yourself.

2. Mesh baking trays
They are made with their own hands from a wooden frame and a mosquito net. It is better to connect the frame slats using self-tapping screws, and fasten the mesh using a furniture stapler. To prevent the mesh from coming apart, its edges are folded several times. It is necessary to stretch the mesh onto a wooden frame first in width and then in length.

3. Rails for placing baking sheets in the dryer
They can be made from the same wooden slats measuring 5*8 mm in profile. They are attached to the wooden body using self-tapping screws.

Let's start calculations and installation

Step 1. We do without nails

For this device, nails are completely unreliable. In this case, the author of the master class recommends using self-tapping screws. To prevent the self-tapping screw from damaging the integrity of the structure, drill a hole with a smaller diameter than the diameter of the self-tapping screw leg and only then screw it in.

Step 2. Decide on the design of the future dryer

Ilya Tretnikov suggests considering two types of dryer designs for vegetables and fruits. The first type - with a volume of up to 13 kg when loading products, square. The second type - the design is complicated and loading volumes of fresh products are possible up to 40 kg. This option is complemented by a pyramidal installation for fans that ensure uniform air circulation. Thanks to the pyramidal shape, the air flow receives a specific direction of movement and reaches the farthest corners.

Step 3. Selecting fans

According to the recommendations of the author of the master class, in a dryer with a depth of up to 57 cm, a height of the internal working surface of up to 39.5 cm, and a width of 41 cm, only one fan is sufficient to obtain high-quality output products. Accordingly, wood with a thickness of 1.7 * 1.7 cm is used, and we get the deco size - 41 * 45 cm.

Basic calculations:

Total depth of the dryer (57 cm) – length of the baking tray (45 cm) = space for air circulation (12 cm). If you are making a dryer for fruits and vegetables with a load of up to 13 kg, this is enough.

When constructing a dryer for fruits and vegetables, along with a pyramidal design and dimensions: width of the internal working surface - 61 cm, height of the internal working surface - 83 cm, depth - 42 cm - 2 fans are installed. Baking tray size 41.5*60.5 cm.

Basic calculations:

The total height of the dryer (83 cm) – the length of the baking sheet (60.5 cm) = space for air distribution from the main body to the wall of the attachment (22.5 cm).

Step 4: Thermostat and Electricity

In order not to delve deeply into physics, Ilya Tretnikov recommends simply buying a “dutik” heater, as it is popularly called, and immediately receiving a set of all the necessary parts.

The main thing is the thermostat built into the fan, which is placed in the middle of the heater body. The author of the master class places it inside the working chamber of the future dryer. Using a regular thermometer, Ilya manually adjusts the thermostat. To do this, it is necessary to rearrange the contacts so that the effect of the thermostat applies only to the heating element. This means that when the maximum temperature is reached, only the coil will automatically turn off, and the fan will continue to operate. When the coil cools, the thermostat will start it again. It is worth paying special attention to this point, since the factory assembly of the heater involves turning off both the heating element and the fan by the thermostat. The method created by Ilya is much more economical in energy consumption.

Step 5: Installing the spiral

Step 6: Install the Dryer Switch

It is better to distribute the functions of the switch in this way: fan on / heating coil on and fan / off.

Step 7: Dryer Operation Indicators

Ilya uses 2 light bulbs:
- the first is an indicator of the overall operation of the device, that is, it lights up in the “on” position, does not light up in the “off” position
- second – indicator of the “on”/”off” positions for the heating element.

Step 8: Install two fans in a pyramid design

When creating a dryer with a pyramidal design, Tretnikov uses 2 fans, each with one heating coil. But the operation of both heating elements will be adjusted by only one thermostat. That is, it is very important to result in the simultaneous opening of the heating elements, since otherwise the drying process will become uneven. To ensure the uniformity of temperatures, it is enough to place several thermometers on different planes throughout the entire cavity of the dryer.