Keeping food fresh, chilled or even frozen outside the home and without a stationary refrigerator can be easily and simply with a thermal bag. For those who have not yet acquired such a useful accessory, it will probably be interesting to know how the cooler bag works and what determines its effectiveness. Let's figure it out!
Types and principle of operation of cooler bags
Refrigerator bags on store shelves are now apparently invisible. They come in different shapes, colors and sizes. However, functionally, such accessories are divided into:
- thermal bags;
- bags with cold accumulators;
- car refrigerators capable of cooling the air inside themselves.
Let's look at these varieties in more detail.
Thermo bag, only able to keep cold. It is arranged according to the principle of a conventional thermos, moreover, such an accessory can not only maintain low temperatures, but also keep food hot. That is, you can always enjoy ice cream on the beach or treat your friends to warm pizza at a picnic outside the city.
The thermo-bag has a very simple structure - it has an insulating foil layer inside, for example, foamed polyurethane or foil insulation. Such a bag is tightly closed and can maintain the same temperature inside the chamber for 2-3 hours. This bag is very convenient to use if you lead an active lifestyle and spend a lot of time on the road and on your feet. The bag can be worn on the shoulder. There are models made in the form of backpacks, and after use, such an accessory is curled and does not take up much space. There are also thermal boxes. They have a rigid structure, and foam can act as an insulating material.
If on a hot summer day you buy fruits or drinks at the market, put them in a regular thermos bag and go outdoors - you will have to feast on warm fruits and drink warm drinks.
But a bag with cold accumulators can help you out in such a situation and cool the purchased products a little. In fact, this is a regular thermos bag with a thick insulating layer inside. But complete with such a purchase, cold batteries are also sold - sealed flasks with saline or a special gel inside. Such a battery must first be frozen. If the frozen container is placed in a thermo-bag, then the saline solution will thaw very slowly, rendering the food cold inside. The use of rechargeable batteries increases the storage time of food inside the thermos bag - by about 10-12 hours.
However, there are container bags that can actively and continuously cool the air and food inside. These devices are powered by an outlet or car cigarette lighter. Thanks to this, the auto-refrigerator can work for several days. As a rule, such containers are distinguished by the largest volume and are created for autotourists, travelers and those who travel to nature in a large company.
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What determines the time of keeping the temperature inside the thermal bag?
Of course, when buying a cooler bag, we all want our acquisition to be as effective as possible and serve us as long as possible. That is why, when choosing this or that model, focus on the thickness of the insulating layer, ergonomics and the device of your purchase, the presence or absence of cold accumulators, etc.
Remember that a bag made of dense material, with a secure fastener and a protective flap, with a thick insulating layer, is able to maintain temperatures 15 ° lower than the environment. However, without cold accumulators, this effect will be short-lived - about 3 hours.
By the way, we strongly do not recommend buying a cooler bag if you are not sure that the thermal layer in it is more than 0.8 cm.The thinner polyurethane or foil insulation is simply not able to keep cold or heat inside itself, longer than 1-1.5 hours.
If you get cold accumulators or do it yourself, the shelf life of food in the thermo-bag chamber increases by at least 6 hours. And the temperature can be 20-25 ° lower than outside the bag. With the correct placement of food in the middle and a sufficient number of cold accumulators (for 1 liter of food - 50 g of cooler), the temperature retention time inside the bag is from 12 to 24 hours. Depends, again, on the thickness of the thermal layer.
Cold accumulators can be bought ready-made. Or you can use the tools at hand - ice packs, bottles of frozen water or a simple saline solution (for half a liter of water - 3-4 tablespoons of kitchen salt). You can use granular litter from clean baby diapers. It must be wetted, removed from the torn diaper and frozen in a bag.
Try to cool the bag itself before storing food. For example, put it in the refrigerator compartment and put something very cold inside. It is better not just to refrigerate all products to be frozen, but to freeze them well. Well, it's better to pack each product in newspaper or food foil. When stacking food, try to evenly place cold storage accumulators - purchased or made at home. Leave a couple of batteries at the bottom of the bag and under the lid of the bag. Remember, proper stacking of food - plus 1-2 hours to keep the cold inside!
By the way, the frequency of opening the bag, and even its location, affects the time the temperature is maintained. If you put the densest and most reliable bag in the sun or will often look inside, you will not get long cooling and maintaining the desired temperature. The thermal bag should be kept in a shady or cool place, and it can also be covered with a blanket or other items that will interfere with heat transfer. To open your bag less often, get yourself a model with quick-access valves - small side fasteners that allow you to get a small product or a water bottle out of the bag without opening it and letting warm air flow into the middle.
By the way, all the same rules apply in case you need to keep food warm. Only you do not freeze cold accumulators, but heat them in hot water.
See also - How much electricity does the refrigerator consume per month
What is a cooler bag for?
The scope of use of the isothermal bag is extremely wide. Think for yourself:
- You can make large purchases of products without worrying about their safety. Even half a day walking around the market on a hot July day, you can be absolutely calm for the freshness of the purchased meat or dairy products, if you wear them in a thermal bag with cold accumulators;
- You can take cold drinks, ice cream and other products to the beach;
- You can store necessary cosmetics and medicines in a thermal bag that cannot be kept outside the refrigerator;
- You can take perishable food with you on a long trip (to nature, to the sea, to the cottage, on a camping trip);
- You can keep pastries or other dishes, drinks warm, even if you have a sortie or a picnic;
- You can take your lunch, work, study, training in a small thermo-container;
- You can safely wait out an unexpected power outage, repair or defrosting of the refrigerator without losing food from the freezer;
- You can store your fishing catch or hunting meat in the thermal bag.
Some prudent housewives acquire several thermal bags of different sizes for different needs. In a word, it is enough to buy or make a cooler bag with your own hands, and, believe me, you will not have it idle!
A real mini fridge - how it works
As we have already said, in addition to isothermal bags, there are also mini-refrigerators with the possibility of autonomous operation. These are rigid plastic or plywood boxes with a very thick isothermal layer of polystyrene or foam, as well as a foil-coated inner chamber. In addition, when connected to the machine’s electricity or battery, such a device starts to generate cold, acting on the principle of an ordinary household refrigerator. Mini-fridges also have a small amount of refrigerant, a compressor and a piping system. When the power is connected, the compressor starts to drive the refrigerant through the capillary tubes of the device, the air inside the mini-refrigerator chamber begins to cool down.
Sometimes, gas in cylinders is used instead of electricity. However, keep in mind that a 5l cylinder is enough for a week, not more. And yet, such an installation cannot be transported from place to place - it can only function permanently.
More advanced devices work on the basis of such a phenomenon as the absorption of heat at the junction of two semiconductor materials. This phenomenon is known as the Peltier effect. Such a mini-refrigerator can be powered by a simple outlet, a cigarette lighter in the car, or from a built-in generator. Such a model will be completely autonomous - it can be put in the country or carried in the trunk of a car.
As you can see, technology continues to step forward, making human everyday life as comfortable as possible, even where civilization is out of the question. Now, you have the opportunity to sip a cool drink while sunbathing on the beach, even if there are no shops nearby. Now you can go on long picnics and eat fresh food, without the risk of an upset stomach. You can safely defrost and disinfect the refrigerator without breaking your brain, where to put a mountain of products from freezing.
In addition, knowing the principle of operation of the cooler bag, you can choose a truly practical and effective model, as well as use its full potential. Always keep up with the times and live comfortably!
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