Do-it-yourself dryer for vegetables and fruits: solar, infrared, from improvised elements

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Dry­ing is the old­est way to pre­serve fruits and veg­eta­bles. Ini­tial­ly, it was pro­duced 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 your own. How to do this, we will con­sid­er fur­ther.

What is this device?

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

How to choose a dry­er for veg­eta­bles and fruits in a hard­ware store is writ­ten here.

In the blanks, meta­bol­ic process­es are acti­vat­ed, which accel­er­ate the process of their dry­ing. In the process of heat­ing, the mois­ture from the fruits evap­o­rates, and their final mois­ture index is on aver­age 5–8%. To pre­vent a sharp effect of open air flow on the fruits, it is first rec­om­mend­ed to cut them and arrange them on trays, and after 3–4 days sim­ply keep them in the dry­er.

In gen­er­al, two con­di­tions are required for dry­ing prod­ucts:

  • cre­ate a warm tem­per­a­ture regime at which the process­es of evap­o­ra­tion of mois­ture from fruits and veg­eta­bles begin (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, you must pro­ceed from these cri­te­ria. Begin­ner crafts­men can start with solar appli­ances, while more expe­ri­enced crafters can also han­dle the assem­bly of infrared dry­ers.

Solar beam 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. Read on for what you need to do.

Assembly

To assem­ble the solar struc­ture, you will need wood­en bars mea­sur­ing 50x50 mm, but their width and length can be changed based on your own needs. It should be tak­en into account 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 between them­selves to get the out­line 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. Trays must be placed at an appro­pri­ate angle so that the rays warm up the work­pieces well when the cab­i­net is locat­ed at right angles 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, set the frame in the sun and fol­low its shad­ow. When tilt­ing it, 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 mark the loca­tion of future shelves with a pen­cil.
  3. Sew up the side and back walls with ply­wood or lin­ing. In addi­tion, a thin met­al sheet should be attached to the back wall, which will increase the heat­ing of the dry­er.
  4. Build ven­ti­la­tion blocks. In the upper and low­er parts of the struc­ture, from the front and back, nail ply­wood, in which to make round holes of 8 pieces on each side to ensure the release of wet fumes. Close the open­ings with a mos­qui­to net to pre­vent the entry of insects.
  5. Paint the inside of the struc­ture black to cre­ate a green­house effect in the dry­er, which will speed up the dry­ing of fruits and veg­eta­bles.
  6. Install shelves. For free air cir­cu­la­tion in the struc­ture, it is required to use mesh mate­ri­als. For these pur­pos­es, it is best to use a mos­qui­to net, which is fixed on the frame.
  7. Put the cab­i­net on long legs, which are fixed with trans­verse wood­en beams.
  8. Cov­er the front of the frame with a trans­par­ent mate­r­i­al through which the sun’s rays can pass and affect the fruit. For these pur­pos­es, you can use trans­par­ent slate, cel­lu­lar poly­car­bon­ate or glass. For even more heat­ing, you can first place cans of drinks on the bot­tom of the cab­i­net.
  9. From above, close the cab­i­net with a roof made of 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 bet­ter expo­sure to sun­light on fruits and veg­eta­bles dur­ing dry­ing, the struc­ture should be leaned against some sur­face. If there is none, you can use pipes by attach­ing them to the sides of the dry­er.

Operating principle

The assem­bled dry­er oper­ates as fol­lows:

  1. The rays of the sun pen­e­trate the struc­ture through the trans­par­ent coat­ing and heat the rear met­al sheet.
  2. The tem­per­a­ture in the con­tain­er ris­es and exceeds 40 degrees, and there­fore the fruits grad­u­al­ly begin to dry out.
  3. The mois­ture that comes from fruits and veg­eta­bles is vent­ed out­side through the ven­ti­la­tion win­dows, so that the food does not get moldy. So, ven­ti­la­tion needs to be giv­en spe­cial atten­tion so that cold air enters through the low­er hole, heats up and exits through the upper hole, also remov­ing mois­ture to the out­side.

Thus, nat­ur­al air cir­cu­la­tion is car­ried out, and the heat­ing and ven­ti­lat­ing effect is simul­ta­ne­ous. This dry­er mod­el 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 and above, since this will lead to the destruc­tion of a large amount of vit­a­mins and pectins in the prepa­ra­tions, which will ulti­mate­ly reduce their nutri­tion­al val­ue.

In the fol­low­ing video, the home mas­ter clear­ly shows how you can assem­ble a sim­ple but pro­duc­tive dry­er from wood­en beams:

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 is not absorbed by the fab­ric of the dried blanks. So, when mois­ture is removed at low tem­per­a­tures (40–60 degrees), vit­a­mins and bio­log­i­cal­ly active sub­stances are pre­served 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 use­ful sub­stances: 80–90%;
  • vit­a­min loss rate: 5–15%;
  • reduc­tion of blanks in vol­ume: up to 3–4 times;
  • weight reduc­tion of blanks: 4–8 times;
  • stor­age of prod­ucts after dry­ing: up to 2 years in sealed con­tain­ers.

Heating element selection

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

  • pow­er con­sump­tion: 30 W;
  • sup­ply volt­age: 12 V;
  • infrared sur­face tem­per­a­ture: 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 with your own hands in sev­er­al stages.

Assembly

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

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

  1. Cut off part of the wall of one draw­er, as this will keep the opti­mal dis­tance from the sur­face of the heat­ing ele­ment to the prod­ucts inside the draw­er. 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 cut the cor­ner sup­ports of the box. The opti­mal length is 13.5 cm. The fin­ished box will lat­er be the main (low­er).
  2. Take a sec­ond box with a side height of 18 cm. Cut off part of the wall, but do not touch the sup­port­ing cor­ners. Install on the main draw­er for a com­pact and light­weight struc­ture.
  3. Pre­pare a hold­er for infrared heat­ing ele­ments. For this, you can use dou­ble-fold­ed card­board with a thick­ness of 6 mm, since it will pro­vide greater rigid­i­ty. So, you need to cut out three card­board par­ti­tions along the con­tour of the box — the top, mid­dle and bot­tom.
  4. Take ordi­nary food foil and glue the par­ti­tions as fol­lows: the low­er and upper ones on one side, and the mid­dle one on both. You can use dou­ble sided tape to attach the foil. The foil is used as a reflec­tor as it helps direct the infrared rays gen­er­at­ed by the heat­ing ele­ments onto the food.
  5. Attach the heat­ing ele­ments to the foil par­ti­tions using dou­ble-sided tape. Do it as fol­lows: attach 2 ele­ments to the upper and low­er par­ti­tions (4 in total), and 2 ele­ments to each side (4 in total) to the mid­dle one. In this case, it is nec­es­sary to make all the con­clu­sions of the heat­ing ele­ments in one direc­tion, so that it is eas­i­er to con­nect. At this stage, the assem­bly of the dry­er is com­plet­ed, so it remains to con­nect.

It should be not­ed that there may be free areas on the par­ti­tions that could not be cov­ered with heat­ing ele­ments. You should not wor­ry about this, since there is a small spread of infrared rays, so they will heat the entire area of ​​u200bu200bthe trays, that is, all work­pieces will dry under such influ­ence.

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 dry­ing will require a volt­age of 12 V. To ensure it, it is advis­able to use a 220/12 V step-down trans­former with a pow­er of 250 W. Here are its char­ac­ter­is­tics:

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

The con­nec­tion stage must be giv­en spe­cial atten­tion, because in case of incor­rect or unre­li­able con­nec­tion, the device sim­ply will not work, and the fail­ure of the heat­ing ele­ments can lead to dam­age to the step-down trans­former.

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

Heating elements connection diagram

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

Dryer connection diagram

Hav­ing dealt with the cir­cuit, you can pro­ceed direct­ly to the con­nec­tion of the wires to each oth­er. In this case, it is worth using flat female-male con­nec­tors, 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, one of the heat­ing par­ti­tions can lat­er be turned off so that only one draw­er works. This is con­ve­nient if you want to dry a few prod­ucts.

Con­nec­tion work is 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. Addi­tion­al­ly secure with elec­tri­cal tape of dif­fer­ent col­ors to pre­vent con­fu­sion when con­nect­ing the female-male con­nec­tor to the trans­former. In gen­er­al, duct tape will help keep mois­ture out of the joints.
  3. Make the con­nec­tion on the trans­former with 4 con­nec­tors for each polar­i­ty. To do this, you need to use 4 wires of dif­fer­ent col­ors, which will facil­i­tate the con­nec­tion process. Care must be tak­en when con­nect­ing the trans­former con­nec­tion to the cable that will be con­nect­ed to the 220 V net­work.
  4. The design is ready, so it remains only to assem­ble the entire sys­tem. To do this, you need to insert par­ti­tions into the frame: the top one — on the top box with the heat­ing ele­ment down, the mid­dle one — between the box­es, the bot­tom one — under the sec­ond box with the heat­ing ele­ment up.
  5. Plug in the trans­former.

Examination

To test a home­made dry­er, you can use a ther­mal imager, as 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 12 V heat­ing ele­ments. In this case, the pho­tographs will show that they cre­ate infrared radi­a­tion over the entire sur­face of the dry­er, which is required for dry­ing fruits and veg­eta­bles.

With the help of a ther­mal imager, it will also be pos­si­ble to deter­mine how much the entire struc­ture heats up. Nor­mal­ly, the card­board reflec­tor will heat up to 34 degrees. This will mean that the bulk of the infrared rays are direct­ed in the right direc­tion, that is, on 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 a pleas­ant warmth. There should not be any unpleas­ant odors.

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

Homemade dryers from improvised items

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

Homemade fruit dryer

air grill

It is required to per­form a series of sim­ple manip­u­la­tions to turn an air grill of any mod­i­fi­ca­tion into a dry­er. The instruc­tion looks like this:

  1. Remove a bak­ing sheet from the stove, on which to spread veg­eta­bles, fruits, berries or mush­rooms.
  2. Remove the cov­er with the lamp and fan from the air fry­er.
  3. Take the high grid from the kit for the bak­ing sheet and place it exact­ly in the mid­dle of the bak­ing sheet, while it must rest firm­ly on the steel, and not swing.
  4. Place the 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 air­fry­er lid on the floor, stool or table. At the same time, it is impor­tant to mon­i­tor safe­ty in order to pre­vent fire. It is worth keep­ing away cur­tains, pets and chil­dren.
  7. Start the con­vec­tion oven accord­ing to the instruc­tions at a low tem­per­a­ture, while cau­tion is required, since the heat will be quite strong.
  8. Set the makeshift dry­er timer to 60 min­utes. At the sig­nal, mix the work­piece, and after 20 min­utes turn it on again. Con­tin­ue until the prod­uct is com­plete­ly dry.

Fridge

If you have an old refrig­er­a­tor and you don’t know where to put it, then you can eas­i­ly turn it 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 cloth­ing and rub­ber gloves.
  2. In the low­er and upper parts of the refrig­er­a­tor, make win­dows through which air flows will enter the struc­ture, and then exit.
  3. Fix the door using a reg­u­lar hook. If it is slight­ly bent and a notch is made on it, when closed, the door will fit as tight­ly as pos­si­ble to the refrig­er­a­tor, ensur­ing a her­met­ic clo­sure of the case.
  4. As a bot­tom, install a fine-mesh met­al mesh.

Grill grates

A prim­i­tive appli­ance can be assem­bled using a grill grate. Pro­ceed in this order:

  1. Remove the wire han­dles from the grill.
  1. On the grid, fix the fan, which is equipped with a motor. A sim­i­lar ele­ment can be obtained from old tech­nol­o­gy or made inde­pen­dent­ly. If there is no fan, two 150 W incan­des­cent lamps can be used as a replace­ment. It is worth con­sid­er­ing that in the case of using lamps, dry­ing will take a lit­tle longer.
  1. Install trays at the top of the box, which will be affect­ed by the air flow from the fan.

Heating film

It is used for the instal­la­tion of under­floor heat­ing. Based on it, you can make a sim­ple and eco­nom­i­cal dry­er.

You will need the fol­low­ing mate­ri­als:

  • heat­ing film 50x100 cm in size and 110 W;
  • elec­tri­cal wire with plug and switch;
  • insu­la­tion kit.

Expe­ri­enced crafts­men rec­om­mend using bitu­mi­nous insu­la­tion, which is used for installing infrared floors. On top of this mate­r­i­al, it is worth lay­ing PVC insu­la­tion, which can be pur­chased at the 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, an eye­let and a ter­mi­nal — rings.
  2. Con­nect the wires with a sol­der­ing iron. Dur­ing the sol­der­ing process, it is worth plac­ing a met­al bar under the film to pre­vent it from over­heat­ing.

After con­nect­ing the wires, you can get a dry­er, the tem­per­a­ture of which can reach 58 degrees, which is quite enough for dry­ing prod­ucts. Such a 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 offers 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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