How does a catalytic heating pad work? Principle of operation and instructions for use. Catalytic warmer: instructions for using the device Homemade hand warmers

Baking soda (sodium bicarbonate) readily reacts with acetic acid to form salt (sodium acetate) and weak carbon dioxide, which immediately dissociates into carbon dioxide and water. All components and reaction products are completely harmless, and the gas-rich mixture actively foams, making the pies more magnificent and forcing students to point fingers in surprise.

CH 3 COOH + NaHCO 3 → CH 3 COONa + H 2 CO 3 H 2 CO 3 → H 2 O + CO 2

Sodium acetate is widely used not only as food additive(E262), but also in the chemical industry - when dyeing fabrics, vulcanizing rubber, etc. - and, of course, as part of warming "salt warmers". This substance melts at a temperature of about 58 ° C and easily dissolves in water, and if you then evaporate excess moisture from it and cool it, you can get a supersaturated solution that waits only for a slight "push" in order to instantly crystallize.

This exothermic process is accompanied by the release of a large number energy - from 264 to 289 kJ / kg. Unlike the production of sodium acetate, this is not chemical reaction, but a physical process, a phase transition, and it is completely reversible. It is necessary to heat the mixture (for example, in a water bath), the acetate will again dissolve in the remaining water, and the "heating pad" can be reused.

Having briefly familiarized ourselves with the theory, let's move on to practical training... Of course, you can buy a "saline heating pad" at almost any pharmacy, and ready-made sodium acetate - in the first suitable chemical store. But why? All the ingredients you need can be found in your own kitchen.

Take a suitable container (a saucepan will work fine) and add food vinegar. Keep in mind that as a result, the volume will decrease by about an order of magnitude - we had to prepare the acetate solution in several batches.

Add baking soda carefully, do not rush, letting each new portion react, otherwise you really have to get acquainted with the "chemical volcano". For every 500 ml of a 9% vinegar solution, we used 4-5 teaspoons of baking soda.

We got an acetate solution, from which it was left to evaporate excess water. Place the pot on low heat and let the liquid simmer until fine crystals of acetate begin to appear on the sides. At the same time, the solution becomes yellowish and decreases in volume by almost 90% - this can take an hour or more.

While our solution was evaporating, we made an activator for the heating pad: we took out the base, a curved metal tape from the ruler bracelet, and cut out a circle from it, which, when pressed, bends in one direction or the other with a click. To prevent such a "button" from damaging the heating pad, it was tightened with electrical tape.

Warming "volcano"

We poured the oversaturated acetate solution into a heating pad, putting our activator in it - but in principle, the reaction can be started without it. It is enough to throw in one of the crystals that remained on the walls of the dishes, and once spontaneous crystallization began with us simply from a sharp blow. The heat in such a heating pad can last up to several hours, and for reuse it is enough to heat it in a water bath, again converting the acetate into a liquid form.

The article "Homemade heat, a chemical heating pad with your own hands" was published in the magazine "Popular Mechanics" (

Evgeny Sedov

When hands grow from the right place, life is more fun :)

Content

There are several different devices that are used to heat small spaces and personal heating person. One of them is a catalytic heating pad, available on the market in a large assortment. A prerequisite for the creation of this compact device was the inconvenience experienced by soldiers during the First World War in winter period... Find out everything about this device: about how it works, models and prices.

What is a catalytic heating pad

This device is a chemical heating pad, the purpose of which is to individually warm a person with the help of flameless oxidation of high-purity gasoline vapors. Over the four years of the First World War, the inventors of England, Japan and the United States created several versions of pocket-type liquid heating pads. To start the device, the reservoir was filled with alcohol, which was absorbed into the cotton wool, after which the device was heated by the flame of a match - as a result of this, a catalytic reaction occurred.

Today, a catalytic warmer for hands and heating other parts of the body has found wide application among lovers of hiking, fishing, hunting, and winter sports. She gained great demand in the conditions associated with working on the street. In the Soviet Union, manufacturers produced a gasoline heating pad GK-1, which, when fully refueled, was capable of generating heat for 8-14 hours from temperature indicator up to 60 degrees.

The principle of operation of a catalytic heating pad

The catalytic heater device is relatively simple, because the device consists of a body made of metal, without additional external parts. In terms of size, most models are about the size of the palm of an adult man. A reservoir is located inside the housing, and a catalyst is attached to the neck. The latter contains cotton wool, which is soaked in gasoline. The neck is closed with a tight lid, but there are holes in it through which air flows to the catalyst.

The principle of operation of the device is based on the release of heat, which is accompanied by flameless oxidation of gasoline vapors in the presence of a catalyst. Gasoline vapors pass through a special catalytic cartridge. They are oxidized by oxygen on the surface of an already heated catalyst, i.e. these vapors burn without a flame. Oxidation products escape from the instrument through the ventilation holes in the cover. At the same time, air containing oxygen begins to flow through them to the catalyst surface.

The catalyst (catalytic gauze) is a platinum part that looks like a wick - this is the most important component of the heating pad. Inside it is a steel mesh cartridge. To run the mesh in a catalytic cartridge, it must be heated for 10-15 seconds using a flame that does not give off soot, for example, a lighter. The fuel used for the heater is gasoline that has passed the highest degree of purification. The use of other types of fuel leads to rapid deterioration of the mesh - a phenomenon called "catalyst poisoning".

Method of using a catalytic heating pad

It is possible to increase the efficiency of a device that has been clogged by calcining the mesh cartridge together with the catalyst in a muffle furnace or on a gas (non-smoking) flame. Remember that the use of individual catalytic devices in closed rooms is hazardous to health, because gasoline oxidation products are highly toxic. It is necessary to use a catalytic type heating pad in accordance with the instructions:

1. Place the device on a flat surface. If the weather is cold, then warm up the device before starting - for example, you can for 10 minutes. place it under your clothes.
2. Enter the required volume of gasoline for lighters or any other option that has passed the highest purification into the tank using a special watering can / funnel (included in the set). Please note that you must not refuel the heater with gasoline.
3. Be sure to fix the watering can using a special clip. This approach will help avoid leaks.
4. Remove the watering can and put the catalyst in its place.
5. Make sure that there is no spilled fuel on the body of the device, after which you can heat it up with a match or a lighter.
6. The catalyst will heat up to the desired temperature in about 5-10 seconds.

For long-term use of this pocket device, it is very important to follow certain rules of care. The main thing is that before each refueling, it is imperative to shake out the remaining fuel from the tank. Over time, when the surface of the device becomes dirty, warm it up for 1-2 minutes. over the flame gas stove- this way you will restore the device to its previous state. This will bring the heating pad back to its maximum temperature.

During operation, the surface of the catalytic device is capable of heating up to 60 degrees. This temperature is somewhat high for contact with the human body, therefore, in addition to the device, the kit also includes a special bag - in it you need to hold the device. This kind of cover is also necessary to protect the device from cooling, because cold air may cause it to stop working due to insufficient fuel evaporation. Typical uses:

• warm your hands by placing a heating pad in a mitten or keeping it in your pocket;
• dry shoes by placing the device inside the shoe;
• keep warm at night by placing the device in a sleeping bag.

Catalytic heating pad manufacturers

The final cost of a heating device depends on the country of origin and firm. On the market there are models of domestic production, Korean, Chinese, etc. High-quality models cost from 1.5-2 thousand rubles and more. Their difference from cheap counterparts lies not only in the quality of manufacture, but also in fuel consumption - they are more economical and at the same time emit less gasoline odor during operation. TO renowned manufacturers hot water bottles that are widely used by fishermen, hunters and travel enthusiasts include:

• ZIPPO;
• KOVEA;
• Pathfinder.

ZIPPO

ZIPPO heating pads are capable of generating heat for 12 hours. They are used to warm the hands and body of a person. Heat is released without combustion due to the oxidation of gasoline vapors. The mesh (catalyst) is made of fiberglass. The Handwarmer High Polish Chrome model can be an excellent purchase. The device will be useful for fishing, walking, hiking and just in the cold season, for example, for car owners who sometimes have to repair their car in the cold:

• name: Zippo Handwarmer 40365 High Polish Chrome;
• price: 2295 rubles;
• characteristics: dimensions - 66x13x99 mm, weight - 73.7 g, manufacturer - USA, there is a lifetime warranty from the manufacturer, original gift wrapping;
• pluses: durability, gives soft, stable heat for 12 hours;
• cons: expensive.

ZIPPO heating pads are a real lifesaver for sellers who have to stand idle in the winter behind the counter. Another great option from this company:

• name: Zippo 40363 Pink;
• price: 2090 rubles;
• characteristics: dimensions - 51x15x74 mm, weight - 51, steel with a pink matte finish, keeps heat for about 6 hours, warranty - 2 years;
• pluses: compact size, reliability;
• cons: high cost, keeps heat less than analogs;

KOVEA

The Korean manufacturer of catalytic heating devices is KOVEA. This company has been occupying one of the leading places in the market of such heating pads for several decades. The quality of its products is beyond doubt. Distinctive feature the KOVEA heating pad lies in its ergonomic design. In addition, the standard kit often includes a handy pouch for the heating pad. The VKH-PW05M Pocket Warmer M model is ideal for warming hands, feet and for drying boots and gloves.

I recently bought this amazing device and I want to tell you about it.

The catalytic heater is an amazing invention. This little thing heats up to 60 degrees and runs for 6 to 24 hours on a single gas station. I bought a Chinese one for 250 rubles. It is made soundly, the metal is decent, it suits me.

Runs on refined gasoline (for lighters), for example "galosh".
The principle of operation of the heating pad is based on the release of heat during the flameless oxidation of gasoline vapors in the presence of a catalyst. Heat without smoke and fire, almost no smell. The catalyst looks like a shaggy insole made of a refractory material, such as asbestos, and looks like this:

In the dark, you can see how it smolders, and inside it an oxidation reaction takes place with the release of heat:

Wikipedia says that the catalyst is made of platinum, and this is the most important part of the heating pad - efficiency and durability depend on it.
IN good heating pads the catalyst looks like this:

Left GK, right Zippo. Look at Google, one such "replaceable catalytic element" costs 2-3 times more than a Chinese burner.

Today I decided to check: I refueled it, lit it, put it in my pocket and went on business. And every time I put my hand in my pocket, I wondered how effectively this contraption worked. They say that for her it doesn't matter what position she is in, even upside down, the main thing is that there is little access to air. The heating pad gets very hot, so you can even get burned without a cover. In the case it looks like this:

In winter, you can put it in your sleeping bag at your feet and hands, and sleep in comfort. The heating pad can be applied to the gas cylinder of the burner, (just in case, through the cloth) there is just a concave bottom and the burner will start even in subzero temperatures.

And this is a heating pad Zippo Handy Warmer The price varies from to rubles.


Outwardly, the shape and structure of the catalyst are similar to the Chinese one.

It differs from the Chinese zippa in that the catalyst lives much longer, for the Chinese one it is about 1500 hours (2 months of continuous operation)
It differs from Soviet heating pads GK-1 and American JON-E of the 60s by a reduced consumption of gasoline (1.5 - 2 times) because it is done better and gasoline does not evaporate in vain into holes and cracks.

I believe that the quality of the burners is equivalent to their cost, which one to buy is up to you.

And the catalytic burner itself is an excellent device: it consumes very little gasoline, it works for a long time at 1 gas station, heat, light weight, durability. I recommend to all.

Winter came imperceptibly, I felt it when on the way to the store my hands were very cold. Of course I know about gloves, but they do not warm, but only keep the warmth of our hands.So I decided on hastily to assemble a mini heating pad specially for my precious hands.There are a lot of hot water bottles of such a plan in the markets, but still he wanted to make his own.

On sale there are heating pads with a combustible mixture inside, these are camping heating pads with a long reserve based on the principle of catalytic combustion. There are also electric heating pads with a built-in battery and a heating element.

A long time ago I bought several power banks with a metal case, and a heating pad was assembled on the basis of this case.

My heating pad will be electric.

On aliexpress, I bought an infrared heating element used as a heater for a warm floor, they are also wrapped around water pipes so that the water in the latter does not freeze. Well, in general, there are a lot of areas of application for such a heater.

The heater consists of two parts - a fiber resistive material that is actually heated, and a heat-resistant flexible insulation.
Such heaters are powered from the mains, 10 meters of such a wire consumes about 160 watts when powered from a 220 volt network. It was this material that I decided to use in my heating pad.

Empirically, I selected the optimal power of the heating element; for this, a nichrome heater was used. I wound the wire on the aluminum frame of the power bank and selected the length so that when powered from 12 and volts, the case heats up to 50 degrees in a maximum of 20-30 seconds, as a result, I revealed that this requires a heater with a power of about 6 watts.

Knowing some initial data and Ohm's law, you can easily calculate the required length of the heater, but you need to take into account the fact that as the heater heats up, the resistance of the heater will increase, therefore the power will decrease, the length and resistance are not so important for my case, since everyone will calculate the heater individually depending on supply voltage and heater length.

The heater will be powered by just one standard lithium can 18650 , but not directly, but through a step-up converter, it is possible without it, but in order to get the required power from 3.7 Volts, you need to shorten the length of the wire and connect several in parallel. To avoid the collective farm, I decided to use the converter, in this case the heater will be one-piece and will stretch along the entire length of the sleeve, thereby ensuring uniform heating.

In the heating pad, the battery must be protected, otherwise it may fail due to a deep discharge.

I kept some distance between the turns of the heater, having received something like grooves for fingers, so that the heating pad fits perfectly in the hand.

A cheap MT3608 handkerchief is ideal as a boost converter, we supply 3.7 Volts to the board input and turn the trimmer resistor at the module output to 12 Volts. My case turned out to be too small and the converter board simply did not fit, but did not want to change the case, in the end I decided to modify the inverter shawl with wire cutters, and that's what happened.

The size has decreased by two and a half times.

We will make measurements of power and operating time. We supply a voltage of 3.7 volts to the input of the inverter, simulating a battery, connect a heater and a wattmeter to the output of the inverter.

The battery consumption is slightly less than two amperes, of which about 100mA is consumed by the wattmeter itself, which is a little more than 7 watts at the input, and at the output we have 4.5-5 watts, the efficiency is about 70%.Naturally, without an inverter, there would be less losses.But even with all this in mind, a 2200mA / h battery will last a little more than an hour of continuous operation of the heating pad, and if this is not enough, you can take a 3400mA / h battery.

A heat-resistant adhesive tape is wound on the aluminum case of the power bank, in principle it is not needed, it was originally used for thermal insulation of the case. This is necessary so that the battery does not overheat, but later tests showed that most of the heat will be directly transferred to the hand, and the temperature inside the case is not critical.

Despite the stripped-down converter board, I had to lengthen the case, since I completely forgot that in the beginning I was planning to shove the charging system here from the USB.

The heating pad is turned on with a button without fixing.

Hello everyone. Fishermen, hunters, tourists, in general, everyone who reads this article.

Today I will share my idea - how you can make a hand warmer from a SIMPLE PENCIL.

Such a heating pad can provide very good heating, with a relatively low consumption. (SPECIFICALLY, what I got will be lower).

THIS ARTICLE IS NOT A INSTRUCTIONS FOR ASSEMBLING HAND WARMERS, BUT ONLY A DEMONSTRATION OF MY IDEA, ITS IMPLEMENTATION AND WHAT HAS BEEN GOT FROM THIS. REMEMBER YOUR SAFETY IS IN YOUR HANDS.

I took the most ordinary graphite pencil as a basis for such a heating pad (here you can experiment a little with the length and thickness of the rod).

The most common one came up for 8-15 rubles in wooden clothes (it can be more expensive, there is a denser wood, better heat transfer + -3-5 degrees difference) with the same consumption.

As it turned out, plastic (ECO) -that bending is not suitable because they do not conduct current.

Now I decided on a pencil-vibrated the length and the required heating.

grinded it to the desired diameter (cleaned off the paint - reduces heat dissipation) - made additional cuts.

Here it was revealed that the neck itself (without a shell) - heats up very strongly, usually + 15C to the fact that it is in the shell, but without it it becomes very vulnerable (brittle).

I tried different variants protection of the rod .. from simple heat shrinkage to various tubes. Moroki is a little useless. I decided to leave it in its own shell, I just grinded it off as much as possible and made cuts. ON THE PHOTO pencils with different shells (loose and hard wood).

The next step was to connect the USB WIRE - (it was not so simple here - do not solder .. do not squeeze properly).

I tried two of these options for connecting the wire to graphite.

I liked BOTH options (in my own way). If you know your a good option connection to graphite-write-it will be interesting.

After connecting the wire, everything was neatly packed with heat shrinkage.

The result is such a hot-water bottle from POVERBANK.

At the time of this writing, it has worked for more than 150 hours (on average, 3-6 hours, depending on the power bank). The heating pad works clearly, the POVERBANKS are still intact.

The heating pad that is in the photo and in the video heats up to 70C AT 0.7-0.8A - to be honest, this is a lot for the hands (even at an ambient temperature of 0-2C, it gave out 50 + 55C, too much for me (but this is a test version)

The maximum that I managed to squeeze out with a good ratio of + 45 + 50C OR + 30 + 35 was measured at 0-2 (for me the most comfortable temperature). THIS is at 5V-0.5-0.6A.

The length of the wire is already a matter of convenience (the main thing is more powerful, so that it would pull such a strap)

The shell is also a matter of aesthetics and convenience, the main thing is that it has good thermal conductivity.

Well, in principle, all dear readers, the heating pad works and heats up.