Many medical institutions today install specialized refrigerators. Moreover, often their presence is a mandatory requirement.

What are medical refrigerators for?

Conventionally, all medical refrigeration equipment can be divided into three large groups:

• Refrigerators are pharmaceutical;
• Freezing medical chambers;
• As well as mobile refrigeration equipment.

And each of these types of technology has its own range of applications. Refrigerators are installed in pharmacies, laboratories, health centers, etc. in the event that it is necessary to ensure the storage of medicines or samples taken for examination at temperatures from plus 2 to plus 23 degrees Celsius.

At the same time, it is necessary to determine the model features of refrigerators. For example, if it is supposed to store narcotic substances, of course, it should be a safe-refrigerator that can be locked with a combination or other lock.

Medical freezers

Such equipment is designed to ensure long-term storage of drugs at fairly low temperatures - from minus 15 to minus 85 degrees Celsius. For example, this may be necessary when storing donated blood, some drugs.

There are quick-freezing freezers. These are intended, as a rule, for high-speed freezing of plasma or blood. You can also note the possibility of acquiring ultra-low temperature freezers. They are designed to solve fairly specialized tasks. For example, they allow storage of viruses or bone marrow, organs, etc. Such devices operate on the basis of liquid nitrogen and can provide cooling down to minus 152 degrees Celsius.

Mobile refrigerators

Compact and lightweight mobile cooler bags perform well at ambulance stations and in general wherever there is a need to transport medicines. Temperature range may vary from model to model. Here the choice must be made based on the specific operating conditions. They can operate offline for up to a day, after which, most likely, they will require recharging or changing batteries.

From this article it will be known what are chemical refrigerators by the principle of operation, by design, as well as what is used as a coolant.

Chemical refrigerator- This is a laboratory apparatus used to collect condensate during the extraction or separation of individual fractions of a liquid, and also as one of the elements of installations for the study of various substances.

As a rule, this is a device made of glass. It is a vessel in which condensation occurs, plus a cooling circuit. Air, water or special refrigerants, including solid ones, can act as a coolant.

According to the principle of operation, chemical refrigerators can be:

• straight;
• reverse;
• universal.

Direct refrigerator (another name is descending) used to separate a liquid into low and high boiling components.

Reverse refrigerator used during high-temperature reactions, while the steam is returned to the reactor (glass flask). Of course, boiling could also be carried out in a sealed vessel, but then there is a high probability of a reactor explosion due to high pressure.

The purpose of these two devices is determined by their design difference. A reflux condenser is installed vertically above the flask with boiling liquid so that the vapor after condensation flows down. A straight refrigerator is installed at an angle so that the liquid from it can freely drain into the receiver.

Universal devices have a design that allows them to be used as direct and reverse refrigerators.

Types of refrigerators depending on the types of condenser vessels

In total, according to the design features, four types of chemical coolers are distinguished. Consider the features of each of them.

Liebig refrigerator

Other names for this downward cooling device are once-through cooler or straight tube cooler (SRT). It was invented by the German chemist Justus von Liebig. The design of the apparatus consists of two glass tubes sealed one inside the other. The inner tube is filled with vapors of a boiling liquid, and running water circulates inside the outer tube.

This design has wide application and may be part of a device by which simple or vacuum distillation is carried out.

Refrigerator Allina

Another name - "ball" device received from the shape of the inner tube, reminiscent of series-connected balls. This design allows you to increase the heat exchange area and increase productivity. But since, with its inclined installation, condensate can accumulate in the balls, the Allin refrigerator can only work as a reverse one.

coil refrigerator

Lauren R. Graham changed the design of a simple chemical refrigerator in a different way by placing a glass coil inside the tube. Condensation in it occurs much faster than in a direct-flow or ball, but the device can only be used as a descending one due to the capillary effect.

A variation of the spiral refrigerator is the Städeler cooling device. Here, ice with common salt or solid carbon dioxide with acetone is used as a coolant. It is used for liquids with a low boiling point.

Dephlegmator Dimrota

It is similar in design to a spiral (coil) refrigerator, but has a slightly different principle of operation of the Dimroth dephlegmator.

This refrigerator is a flask, inside of which there is a spiral cooled by water. The coils of the helix can be extended or tightly wound depending on the application. Liquid vapors condense on spirals and are discharged through an opening at the bottom of the flask. The temperature is easily adjusted thanks to the thermometer fitting located at the top of the flask.

finger-shaped refrigerator

This apparatus is also called a "cooling finger" or immersion cooler. It has a number of advantages: compact dimensions, no need to specifically fix it in the cooling system

Air and water coolers

Depending on the cooler used, cooling devices are divided into air and water.

The air cooler can be used in chemical industry in the synthesis of rubber, alcohol, rectification of oil in areas with limited water resources or to reduce the cost of cleaning, pumping and softening water. Such devices are easy to maintain, do not require large repair and maintenance costs, and also have a longer service life compared to water coolers.

If the condensation reaction occurs at temperatures above 150°C, water cooling will cause the glass to crack due to the sudden temperature change. In this case, an air cooler is used. By design, it can be direct-flow or ball.

The water apparatus for cooling uses running water as a refrigerant. It is used not only in laboratory experiments, but also in industry or medicine, for example, to obtain distilled water. They are made in any of the designs listed above.

Important: regardless of the design of the refrigerator, water or other required refrigerant is supplied to the condenser from the bottom up so that the shirt is completely filled and the operation of the device is efficient.

Conclusion

Chemistry has found wide application in the daily life of modern man. Not only modern housewives use the reaction of the interaction of soda and acid to give splendor to pastries, but laboratory equipment has also found its use. For example, chemical refrigerators are used by those who prefer homemade alcohol to store-bought.

Video: What is a direct and reverse refrigerator | USE Chemistry | Leah Mendeleeva

Video: Refrigerator Overview

Before going to the store, decide on a place for your future refrigerator. Measure this patch with a tape measure (length, width and height): the type of model will depend on this. Consider whether there is enough space to open the doors, whether there is an outlet nearby.

Refrigerators are single, double and multi-chamber. Single-chamber consists only of a refrigerating chamber. Sometimes inside, behind the same door, there is a small freezer shelf.

The height of a single-chamber refrigerator, as a rule, does not exceed 150 cm, width and depth - no more than 60 cm.

Such refrigerators were popular in the USSR, now they are installed in offices and dachas.

Now the greatest demand is for two-chamber refrigerators. They have separate refrigerators and freezers. The first is intended for at a temperature of 5-8 ° C, the second - for freezing.

Freezer power is indicated by snowflakes. One snowflake - the temperature is about -6 ° C, products can be stored for a week. Two snowflakes - the temperature is -12 ° C, the food will lie quietly for a month. Three or more snowflakes indicate that it is -18 ° C in the freezer and food can lie there for up to a year.

Two-chamber refrigerators are:

1. With top freezer(top). Their depth and width are 60 × 60 cm. The height is from 1.5 to 2.5 m.
2. With bottom freezer(combi). The dimensions are about the same.
3. french door(French door). Such models suggest a wide (from 70 cm) freezer at the bottom and a double-leaf refrigerating chamber at the top.
4. (American model). The refrigerator and freezer are located side by side. The width of such refrigerators can reach up to 120 cm. In height and depth, they are usually the same as "top" and "combi".

Multi-chamber (three or more compartments) may have a different layout. A feature of such models is the presence of a zone of freshness. There is a special temperature and humidity, so that vegetables and herbs are like from the garden for a long time, and fresh meat and fish remain chilled, but not frozen.

All modern refrigerators have electromechanical (without fine adjustment) or electronic control. The latter assumes the presence of a panel with a digital display and allows you to set the temperature to a degree, control energy consumption and set special programs(for example, "Vacation" or "Super Freeze").

Some models connect to Wi-Fi: they can be controlled remotely using gadgets.

main parameters

The second thing you need to decide before buying is the technical specifications. In the store, you will only have to select models that meet the specified criteria. A special sticker on the refrigerator door will help you navigate.

Refrigerator volume

Volume is general and useful. The first refers to the entire space along with shelves and drawers. The useful volume is calculated based on the number of products that the refrigerator can hold.

To calculate the minimum usable volume, use the following formula:

120 liters per person + 60 liters per family member.

That is, if you live together, you need a refrigerator with a volume of 240 liters or more. But it is also important to consider the food habits of the family. For example, if you cook for the future and the refrigerator is full, then it is better to take a model with a larger volume.

Defrost type

Soviet refrigerators were defrosted by hand: unplugged, collected water, washed - and use again. Modern models are equipped with a drip defrost system (“Weeping Wall”) or a No Frost system (“No frost”).

1. Drip system: moisture is collected on the back wall of the refrigerator in a special tray and evaporates due to the heat of the compressor. Over time, frost forms on the walls of the chambers, so the refrigerator needs to be defrosted and washed at least once every six months.
2. The No Frost system is based on air circulation in the chambers, the cooling element is placed in a special element of the system, where moisture condenses and evaporates. Frost does not form on the walls of the chambers, so regular defrosting is not necessary. But washing the refrigerator at least once a year is necessary.

If Full No Frost is written on the refrigerator, this means that both cameras are equipped with the No Frost system.

This system is considered the most perfect, but do not forget about its disadvantages. Due to the fan, the usable volume of the refrigerating chamber is reduced, additional noise is created, and products can become airy, so it is better to store them in containers.

Climate class

Depending on the operating conditions, four climatic classes are distinguished.

1. N - operation at temperatures from +16 °С to +32 °С. Suitable for most apartments and houses.
2. SN - operation at temperatures from +10 °С to +32 °С. If the refrigerator will stand in a poorly heated room, for example, in the basement or on the veranda.
3. ST - operation at temperatures from +18 °С to +38 °С. Suitable for regions where it is very hot.
4. T - operation at temperatures from +18 °С to +43 °С. For those who live in a very, very hot climate, or if the refrigerator will stand in a small room in direct sunlight.

90% of buyers do not pay attention to this parameter and choose N or SN class refrigerators by default. But there is an important nuance.

If the refrigerator breaks down and the examination shows that the operating conditions did not correspond to the climate class, the manufacturer's warranty will not work.

Type and number of compressors

There are absorption, thermoelectric and compressor cooling systems. The first ones, although silent, are not very popular with domestic consumers, as they require a lot of energy and have a number of other disadvantages.

Most household refrigerators are equipped with one compressor that runs simultaneously on the refrigerator and freezer compartments. The cameras cannot be turned off individually, but in modern models there is a “Vacation” option: when the freezer is running, the refrigerator compartment goes into economy mode.

In two-compressor models, the refrigeration compartment and the freezer are completely autonomous, each has its own temperature regime. Two compressors, as a rule, are equipped with two-chamber premium refrigerators and Side-by-Side.

Compressors are linear (turned on / off - turned on / off) and inverter. The latter, thanks to a special current converter, work constantly, but with different power. Inverter compressors are less noisy and wear out and allow. Their disadvantage is the susceptibility to voltage drops.

Noise level

The noise level emitted by the refrigerator depends on the type and number of compressors.

This parameter is especially important if the unit is located not in the kitchen, but in the living room, or if the kitchen is combined with the living room.

energy efficiency

The refrigerator operates 24 hours a day, seven days a week. Therefore, it is important to choose the most economical option.

The energy consumption class is determined based on the nominal and actual power consumption and is indicated in Latin letters.

Nominal value - how much a unit of this type should theoretically consume (100%). Then it is measured how much light a particular model takes. If less than 55% of the face value, class A is assigned, if 75% - B, from 75% to 90% - C, 90-100% - D, 100-110% - E and so on.

The most economical electrical appliances are labeled A, as well as A +, A ++ or A +++. Such refrigerators consume a minimum of energy due to high-quality insulation and modern compressors.

But the energy class does not give an answer to the question of how much energy a refrigerator will consume per year or month. To find out, you need to look at another value in the data sheet: energy consumption kWh / year.

The annual number of kilowatt-hours must be multiplied by the cost of one kWh in your area. So you will find out how much it will cost you to use a particular refrigerator.

Useful and useless options

Sales assistants in stores say little about the main parameters of equipment, but enthusiastically talk about additional ones. They try to convince us that without such and such a sensor or sensor, the device is simply useless. This is no coincidence.

Additional features make the refrigerator more expensive.

Let's see what bells and whistles are in refrigerators and which ones are really useful.

1. Antibacterial coating. The walls of the refrigerating chamber are covered with silver ions, which prevent the growth of bacteria. Sounds like a marketing gimmick: if you keep your fridge clean, you don't need any ions.
2. carbon filter. It drives the air inside the refrigerator compartment and absorbs unpleasant odors (not to be confused with individual flavors). It is not required if you do not allow products to stale, but put strongly smelling ones in containers.
3. Door open indicator. If it is not closed or closed tightly, an audible signal is emitted. Useful if there are children or elderly people in the house who often casually slam the refrigerator.
4. Autonomous cold storage. When the lights are turned off, food stays fresh for a long time. Useful if there are frequent power outages in the region.
5. Super Freeze. This is a mode in which the temperature in the freezer briefly drops to -24-28 ° C. The advertisement says that quick freezing allows you to save maximum amount useful components in products. In fact, it just saves time. There is a similar function for refrigerators: you can quickly cool a bottle of wine.
6. Cold water supply. In budget models, it is implemented as follows: water is manually poured into a special reservoir in the door and permanently cooled. So all this is easily replaced by an ordinary jug of water in the refrigerator. In premium models, water is supplied directly from the water supply. But it's much more expensive.
7. ice maker. Ice cells can also be filled with water manually or automatically. This also affects the price. But first of all, you need to understand how often you freeze ice for drinks and whether it is impossible to do with ordinary silicone molds in the freezer.

What else to pay attention to

So, you have decided on the basic characteristics and nice options. We went to the store and found the right models. What else to pay attention to?

1. What is the lighting inside the refrigerator compartment? It is practical if the bulbs are halogen and are located not on the back wall, but on the sides. So you always see the contents of the refrigerator, even if the shelves are densely filled with food.
2. What are the shelves made from? Glass shelves are the most practical: durable, easy to clean, do not obstruct the view. It is convenient if there are folding shelves or the refrigerator compartment is designed according to the principle of the designer. By changing the location of the shelves, you can even place overall utensils.
3. Do the doors move to the other side? It will come in handy if you are thinking of making a change.
4. Is there a handle on the door? If the refrigerator is in the aisle, you will cling to it.
5. Are the seals on the doors elastic? If the rubber is hardened, the door will not fit snugly.
6. Does the refrigerator have wheels? At least two. Their presence greatly simplifies transportation.
7. Are there any scratches on the case? Any flaws are a reason to take a copy from the warehouse or demand a discount.

After getting acquainted with the characteristics and inspection, you can safely go to the checkout.

What is a refrigerator and why is it needed? This question currently sounds very strange!!! Today in Russia, almost every family owns a stationary household refrigerator, and no one needs to explain the value of this household item. However, only a small part of car owners have a car refrigerator. But auto-refrigerators are indispensable for long trips to the country, on vacation, on a picnic, and even just for long standing in traffic jams, especially in hot weather.

In order for the auto-refrigerator to be a faithful assistant in life, and not turn out to be a useless thing, it is very important to choose the right one. Given the large selection of car refrigerators on the Russian market, the selection process can take a long time. To prevent this from happening, we propose to understand this issue more carefully.

This is a miniature unit that is installed in the car and will help you deliver food to a picnic place in nature, as well as chilled drinks during a long journey. If you like to travel in a car and spend a lot of time on the road, then you cannot do without a portable food storage device. This convenient and compact device will store food and drinks that you are going to take on a long trip.

Car refrigerators have thermoelectric, absorption or compression cooling.

Thermoelectric refrigerators have no moving parts and no refrigerant, so they are environmentally friendly. Cooling of the chamber of the device occurs during the passage of a constant electric current through thermocouples.

The ability to work in the mode of heating products is the main advantage of a thermoelectric refrigerator over absorption and compression. Another advantage is the operability at any inclination of the vehicle. Some models of thermoelectric refrigerators are able to work not only in a vertical position, but also on the side and on the back wall. The disadvantage of thermoelectric refrigerators is a large thermal inertia: they very slowly gain temperature. Before the trip, it is recommended to pre-cool food and drinks in a household refrigerator, or cool the chamber of a thermoelectric refrigerator using cold accumulators. Regular ice should not be used for cooling, as melt water will corrode metal parts.

Thermoelectric refrigerators are made in the form of stand-alone bedside tables, cabinets, chests and boxes of the appropriate shape built into various niches. In order to make the most efficient use of the total volume, all the working elements of a thermoelectric refrigerator are built into the door of the cabinet or the lid of the chest. The easy-to-open lid provides easy access to food.

Most thermoelectric refrigerators operate in cooling and heating modes. Models with a low price level work only in cooling mode and only from the vehicle's on-board network. Refrigerators-food warmers are preferred for long-haul drivers and long-haul flights in all modes of transport. The capacity of thermoelectric refrigerators on the Russian market is from 0.5 to 49 liters.

AT compression refrigerator cooling of products is carried out due to the circulation of the refrigerant, which is provided by the compressor. When circulating, the refrigerant changes its physical state from liquid to gaseous. Cooling of the refrigerator chamber occurs when the liquid refrigerant boils in the evaporator. Compression refrigerators pick up cold faster (less inertial) than thermoelectric and absorption refrigerators and are more economical in operation. They have practically no restrictions on the size of the cooling chambers. The capacity of refrigerators presented on the Russian market is from 18 to 220 liters.

Refrigerator-freezers automatically maintain the set temperature in the range from +4 °C to -18 °C, which satisfies the requirements for storing both fresh and chilled and frozen products. Refrigerators are resistant to vibrations and remain operational at inclinations up to 30 degrees. After a power failure, acceptable food temperatures are maintained for up to 6 hours.

Absorption refrigerators, working on a water-ammonia solution, also do not have moving parts. The circulation of the refrigerant is carried out due to the absorption (absorption) of ammonia by water and the heating of the water-ammonia mixture from an electric or gas heater. The ability to work without electricity on liquid or gaseous fuels is the main advantage of the absorption cooling method over thermoelectric and compression ones. The disadvantages include hypersensitivity to large inclinations at work.

Refrigerators with low prices, operate on direct current 12/24 V. The most expensive, combined electro-gas refrigerators able to work continuously and alternating current and on liquefied gas (propane / butane). The latter mode is more economical than the electric energy mode. Gas models have manual or electric ignition. A gas cylinder with a capacity of 5 liters is enough for 230 hours of continuous operation - this is enough to relax in nature for a whole month.

The capacity of absorption car refrigerators ranges from 24 to 140 liters. Built-in models with one and two doors are installed on executive, intercity and tourist buses, special vans and shift buses, on trucks, yachts and in railway cars.

In terms of specific energy consumption, compression refrigerators are the most economical, absorption refrigerators are less economical, and thermoelectric refrigerators are even less economical. The difference in power consumption increases with the capacity of the refrigerator. The most economical are compression mini-refrigerators in the form of chests with top lids. Chests are more reliable and hold the cold better.

Very important for a car refrigerator, the presence of a protective device that controls the maximum permissible discharge of the battery. It shows when the refrigerator must be disconnected from the car's on-board network so as not to create problems for starting the engine.

In addition to refrigerators, there are isothermal bags and containers. They are used for short-term storage of chilled and frozen products for delivery from the store to the home (from the place of purchase to the place of consumption). To preserve cold and hot liquid dishes, isothermal thermos containers are used in the form of flasks and cans, made from environmentally friendly materials. In an insulated flask, chilled drinks with ice cubes stay cold for up to 10 hours, and preheated drinks stay hot for up to 8 hours.

An isothermal container equipped with a refrigeration unit turns into a car refrigerator, which allows you to significantly increase the shelf life of products. Car refrigerators are made both in the form of free-standing portable models, and for embedding in various niches on vehicles. On passenger cars, they are built into the armrests and in the niches between the seats, on buses - in various niches that are not suitable for accommodating passengers.

When you know the type of your future auto-refrigerator, pay attention to the following things when choosing a specific model.

. Firstly, should be carefully studied technical specification a specific model of refrigerator in a car. Find out also the possibility of power supply from sources with different voltages.

Secondly, it is necessary to focus on the quality of the manufacture of the auto-refrigerator.

Thirdly, befits to learn about the ease of management and functionality of the refrigerator in the car.

Fourth, you should find out the possibilities of transforming the space of the refrigerator chamber.

Fifth, it is advisable to pay attention to the possibility of fixing the refrigerator inside the car in order to avoid unnecessary injuries during the journey of the refrigerator through the passenger compartment, during sudden braking and accidents, since the mass of the refrigerator during the above events can increase several times.

Purchases of automobile refrigerators will inevitably increase as the well-being of the population improves and effective demand increases.