The question of the preservation of products mankind has been puzzled for more than one thousand years. In 2001 in Nigeria, Mohammed Bah Abba received a Rolex Award of $ 100,000 for the invention of the “desert cooler”. He called his invention Pot-in-Pot. A small pot is placed inside a large pot, the space between them is filled with wet sand, the whole structure is covered with a wet cloth. The water gradually evaporates, taking heat from the contents of the inner pot, cooling it. The effectiveness of such a refrigerator is quite high - the temperature decreases in relation to the surrounding by 15-20 degrees Celsius.
Autotourists and travelers, as well as all the rest, need a reliable device that can extend the life of your products.
Kinds of refrigerators
According to the cooling method, automobile refrigerators can be divided into: thermoelectric, absorption and compressor. Each of these refrigeration units has its own design, advantages and disadvantages. Let us consider each option in detail.
The most popular solution when used in conventional cars, due to its low cost, lightness and simplicity of design.
From the history
Jean-Charles Peltier, a watchmaker and an experimenter from France in 1834, placed a drop of water between electrodes made of antimony and bismuth, and then started an electric current through them. The effect struck him - drop is frozen. This effect was named after the person who discovered it - the Peltier effect.
The basis of the thermoelectric cooler unit is thermoelements consisting of thermoelectric semiconductor wafers (Peltier elements). When applied in the cooling mode to the unit of direct electric current, the internal thermocouples (located in the thermobox) are cooled and the outer ones heat up. To put the refrigerator in heating mode, simply change the polarity (change the direction of the current).
- Simplicity of a design, low cost, ease, and reliability. Thermoelectric coolers have no moving parts and no flowing refrigerant.
- The ability to work in cooling mode and in heating mode.
- No dependence of the refrigerator on the angle of inclination.
- In view of the compactness of the refrigeration unit, it is most often placed in the lid of the thermal box. The lid (with wiring) is easily removable, which makes it easy to wash the thermal box itself under running water without fear of damage to the electrical parts.
- Thermal inertness. Thermoelectric refrigerators for a long time gaining the necessary temperature. Manufacturers of such refrigerators write that they can only maintain the cold or warm temperature of food. Therefore, before traveling, the products should be cooled (heated) in familiar household devices, and then placed in a thermoelectric refrigerator. The use of cold accumulators will also be effective.
- Uneconomical. Due to the low efficiency (16-17%), the highest power consumption to achieve acceptable temperature indicators of all the types of refrigerators presented.
The performance of a thermoelectric cooler in cooling mode is usually less than 20 ° C from the ambient temperature. In heating mode, the temperature inside the thermobox reaches 50-60 ° C.
Electricity. Voltage 12/24 or 220V.
Due to its main advantages: low cost, ease, simplicity and reliability of thermoelectric refrigerators are available and very useful to any owner of a car or truck, as well as a bus.
From the history
The principle of cooling by the absorption method was invented in 1858 by the French scientist Ferdinand Carr. In 1922, the first working sample of an uncompressed refrigerator was built by students of the technological university in Stockholm. At the beginning of the 20th century, Moscow offered the Eskimo refrigeration unit operating according to the Carré principle. With large dimensions, the device was silent and versatile. Eel, firewood, alcohol and kerosene were suitable for his work. One cycle of operation of such a refrigerator allowed getting 12 kg of ice.
The name implies that the refrigeration unit operates according to the absorption method. Absorption is a physico-chemical process of absorbing a gaseous substance by a liquid or solid. Namely, the working process takes place due to the circulation and evaporation of the refrigerant (ammonia) in the liquid (hereinafter water). The composition of water-ammonia solution includes: ammonia NH3 (R717 refrigerant), bidistilat of water (absorbent), sodium chromate Na2CrO4 (inhibitor, prevents corrosion on the inner surfaces of the tubes of the refrigeration unit), hydrogen (inert gas, necessary to equalize the pressure in the system). The unit is filled with a water-ammonia solution, weighing 350-750 g, depending on the volume of the refrigerator and hydrogen under a pressure of 1.5 MPa. The concentration of ammonia in the solution is about 35%.
NH3 - hydrogen nitride (ammonia), a colorless gas with a strong odor, which is extremely soluble in water (in a ratio of 1/700 at 20 ° C). Under standard conditions (temperature 25 ° C, pressure 100 kPa) ammonia boiling point is 33.35 ° C. With an increase in pressure in the system (in our case 1.5 MPa), the boiling point (condensation) is approximately 45 ° C. Instead of ammonia in refrigeration units also use: acetone, lithium bromide solution, acetylene.
From the receiver, the concentrated ammonia water solution enters the generator (boiler, boiler) where it is heated (with any heat source) to the boiling point of the solution. The boiling point of ammonia is significantly lower than the boiling point of water, therefore in the process of evaporation of a concentrated solution (at a temperature of about 170 ° C) concentrated ammonia vapors with a small amount of water vapor leave the generator. On the way to the condenser, the concentrated vapor passes through a dephlegmator (heat exchanger). Partial condensation of concentrated steam occurs here. The condensate formed is a weak water-ammonia solution that flows into the absorber, cooled by the environment to the temperature of the beginning of absorption, and even more concentrated vapors with ammonia, through the separator (additional separation of the weakly concentrated solution from the saturated vapors) enter the condenser, where the ammonia cools down, acquires liquid phase (condensed) with heat. Coming out of the condenser, liquid ammonia is mixed with hydrogen and enters the evaporator through a thin tube. As a result of the mixing of hydrogen into the evaporator, the partial pressure of ammonia decreases, which leads to its evaporation at a negative temperature with the intake of additional energy (heat) from the refrigerating chamber. The partial pressure of ammonia in the condenser is equal to the sum of the partial pressures of ammonia and hydrogen in the evaporator. At the same time, the addition of hydrogen does not affect the boiling point of ammonia in the evaporator, since it is determined only by the partial pressure of ammonia vapor. Ammonia vapor coming out of the evaporator enters the absorber, opposite to the weakly concentrated cooled solution moving from the reflux condenser, where the weakly concentrated solution is absorbed (absorbed) by the ammonia vapor. At the same time, as the solution moves along the absorber, it is cooled and a small amount of heat is released into the environment. The highly concentrated solution formed in the receiver, by means of a heat pump, is fed into the generator. The circulation of the water-ammonia solution is carried out continuously while the generator and the thermal pump are running, heated by a heat source. The role of the suction part is performed by the absorber, and the role of the injection part is the heat pump.
- Simplicity of a design, noiselessness and durability due to lack of any moving elements.
- Autonomy. Ability to work from any heat source (electricity, gas).
- Shaking and vibration for such refrigerators are not harmful (within reasonable limits of course).
- Not maintainability of the refrigeration unit. If there is a depressurization of the pipeline connection and the subsequent leakage of the refrigerant - the refrigerator will not help.
- Increased power consumption. It is necessary to constantly warm the reservoir with the refrigerant so that the cooling process does not stop.
- Small efficiency. Part of the energy expended is inevitably converted to heat on a capacitor, which must be brought out into the street. To improve the cooling efficiency, fans (coolers) are additionally installed, which remove heat from the condenser, which also require power. In fairness, we can say that in winter, by closing the ventilation grilles, you can receive additional heat in the cabin from the refrigerator.
- Dependence on the position in space. Since the system does not have a mechanical pump, the deviation of the horizon in space can significantly impair the operation of the refrigerator.
- Long exit to working temperature condition. If the refrigerator is new (or obviously working well), only after 20 minutes you will feel the first signs in the freezer. In the refrigerator, the required temperature will be established after a couple of hours. In old refrigerators it may happen the next day.
Today, absorption refrigerators have won and firmly hold their place in the market. Because of their peculiarities, their application somewhere is not advisable at all, but in other places it is inalienable.
First of all, it comes to gas refrigerators when talking about autonomy (the absence of a constant voltage of 220V). And this is all that goes and floats: motorhomes, caravans, long-haul trucks, buses, houseboats, boats, boats, yachts.
Also such refrigerators are used stationary in conditions of complete absence of electricity. Due to the noiselessness, absorption refrigerators have become widely spread as minibars and mini fridges in hotel and hotel rooms.
Absorption refrigerators can operate from both electricity and gas. In the boiler of the refrigeration unit there are two heating elements, for 12 V and for 220 V. The power of heating elements is usually the same and is about 100 watts. A 220V heating element assumes the operation of a refrigerator in a stationary environment when connected to an external 220V network. A 12V heating element is only used on the way, when it is not possible to connect an external 220V, and it is not safe to use gas on the way. If this is a motorhome, then the voltage is supplied from the internal battery. If you have a caravan, the power to the refrigerator comes from the battery of the towing vehicle. The fog lamp must be on the tractor if the connector of the tractor is a 7 pin. In the 13 pin connector for the refrigerator, a separate contact is provided and nothing additionally is required. The thermostat knob (from 1 to 7) sets the required maintained temperature in the refrigerator.
The operation of the refrigerator from gas implies full autonomy and independence from electricity. On modern models with built-in electronics, gas operation is activated with one button. In older versions of gas refrigerators, skill and skill are required to start. For the first start it is necessary to open the gas cylinder, drown the knob of the gas regulator "away from you", wait about 10 seconds. and start feeding the spark. The spark can be supplied by a mechanical piezo button or electric piezo ignition. In the first case, if you open the door of the refrigerator, in the middle on the left you will see a small viewing window where you can visually check for the presence of a spark and a flame.
It is necessary to hold the gas regulator in the recessed position and simultaneously to give a spark until a blue flame lights up in the window. After that, it is necessary to keep the gas regulator recessed for another 5 seconds, so that the gas control valve would work. Instead of the viewing window, an arrow indicator is used on some models. It is located on the common control panel of the refrigerator. When a flame is ignited, the vertical arrow smoothly changes from left to right (from white to green). If electric piezo ignition is used in the refrigerator, the flame is detected in another way. It is necessary to turn on the ignition switch. His work will be determined by the flashing lamp in it with characteristic clicks. At the same time, it is also necessary to keep the gas regulator recessed. As soon as the lamp on the ignition switches stops flashing and clicks stop, this is evidence that the flame in the refrigerator has been successfully lit. But do not rush to immediately release the gas regulator - 5 seconds. for actuation of the gas control valve are also needed. After successful start-up of the refrigerator from gas with the same regulator (or next to the standing handle), you can change the power of the flame up or down. The more powerful the burner flame, the lower the temperature in the refrigerator.
Possible malfunctions and methods of their elimination
Does not work on electricity (12 or 220V). It is necessary to check whether there is electricity (check plugs, fuses, measure the voltage tester at the entrance to the refrigerator). If there is voltage, the switches are working properly, but the condenser or boiler of the refrigerator is cold - the heating elements may have failed (12 or 220V). Heater need to be replaced. These items can be ordered through the store Retrailer.
Does not work on gas. When searching for the cause and elimination of such a malfunction, you need to act logically. For ignition and burning of gas it is necessary:
- Air (oxygen)
- The output of carbon dioxide and carbon monoxide
1. Check whether there is gas in the system and whether it is flammable. The simplest is to light the stove for cooking. The first launch of the refrigerator, even in the presence of gas, is always long, and especially if you changed the cylinder and air got into the gas pipeline.
2. Check if there is a spark. With a mechanical piezo-spark, the spark can be checked in the viewing window. When electric ignition is on, the spark is determined by the characteristic flashing and blinking of the ignition switch bulb. If there is no spark:
- A break in the wiring or connection between the spark plugs and the electrode located in the burner is possible. It is necessary to remove the refrigerator and carefully examine the wiring and its connections.
- Not good piezo. It is necessary to remove the candle and visually check the spark on any metal object. Instead of the original candle for testing, you can use piezoelectric ignition from a conventional lighter.
- In the case of electric ignition when the spark is not working, both poor contact of the wire and electrode and failure of the piezo-ignition unit are possible. In modern refrigerators, the electronic control board is located behind the refrigerator, opposite the upper ventilation grill. Every time you wash your motorhome (caravan), water inevitably gets there, which leads to the failure of such a board. As a rule, such a fee is not subject to repair. You can purchase a PCB or electrical ignition unit in our Retrailer store.
3. There is a proven gas and there is a spark.There is no flame. Gas does not smell. It is necessary to remove and clean the burner. At the entrance of the gas tube to the burner is a gas jet. It is a "plate" with a calibrated hole, which over time can become clogged with dust. After the nozzle there is a drilling in the burner to release the gas, which can also be clogged with dust, dirt, and soot. It is necessary to thoroughly flush these holes with a compressor.
Attention! The gas jet should only be blown out with a compressor or brushed with a toothbrush. When trying to clean the hole with a metal needle, the jet can be easily rendered unusable. If this happens, it only changes with the burner in our Retrailer store.
4. There is a proven gas and there is a spark. There is no flame. Gas smells. Gas can escape from the side opening (air intake) after the jet, but not from the burner port. It is necessary to do the actions described above.
5. There is a proven gas and there is a spark. The flame does not light up from the spark of the piezo ignition, but it lights up if you bring an open flame (lighter) to the burner. There is a blockage in the burner hole. The blockage does not block the gas outlet to the burner completely, but significantly limits it. The strength of the spark is not enough to set fire to such a small amount of output gas. When an open flame is offered to the burner, additional thrust appears, contributing to the burning of the burner. It is necessary to do the operations described above.
6. There is a proven gas and there is a spark. There is no flame. Gas smells. Or the flame inflames, then goes out. Probably clogged with soot and dirt carbon monoxide withdrawal times. As a result - the lack of traction. It is necessary to remove the refrigerator and completely clean the pipeline.
7. The flame lights up when the regulator is recessed, and when it is released, even after a long time, it goes out. Gas sensor and / or gas control valve is faulty.
8. Everything works, but nothing works. The boiler and condenser are warm, but there is no refrigeration in the cooling chamber. If not only the boiler and the condenser are warm, but the refrigerator itself also resembled an oven, and when turning the refrigerator upside down, nothing gurgles anywhere, the result is sad - somewhere in the pipe weld there was a crack through which the refrigeration unit lost the necessary pressure, and maybe leaked the entire ammonia solution. Such a refrigerator is beyond repair. If the cooling chamber does not heat up, and when turning it over with hearing, the presence of fluid in the aggregate is determined - everything is not so bad.
The problem with absorption refrigerators is the formation of ammonia crystals and hydrogen “bubbles” in the pipeline as a result of temperature changes, long inactivity, as well as metal particles as a result of corrosion, which makes it difficult / impossible for the fluid to move around the circuit. It is necessary to turn the refrigerator upside down and let it stand for half an hour, so that all the liquid from the separator goes through the pipeline and sinks to the boiler. The liquid will collect in its path all the crystals, hydrogen plugs and other debris. After that, the refrigerator must be returned to its original position, wait until all the liquid has flowed down and immediately turn it on from any heat source. It is very likely that after this absorption refrigerator will serve you more than one year.
For the prevention and the approach of the old refrigerator to the factory figures, Retrailer recommends to make such an acrobatic number with a gas refrigerator by the beginning of each season. If your refrigerator doesn’t help anymore, we always have the workers of the used refrigeration absorption refrigerators that you can buy at an affordable price.
Cooling occurs due to the circulation of the refrigerant (most often freon), which is provided by the compressor. During circulation, the refrigerant changes its physical state from liquid to gaseous. Refrigeration chamber cooling occurs when boiling liquid refrigerant in the evaporator.
- Higher efficiency. The difference is especially noticeable in the southern regions of Russia, when the external temperature exceeds 30 ° C.
- The most profitable by specific energy consumption. The compressor does not always work, but only when necessary.
- No dependence of work on the position in space.
- Maintainability. It is possible to solder a depressurized radiator with a subsequent refrigerant charge at a specialized service, as well as replace the compressor.
- Exits to working mode quickly and efficiently.
- Minus all compressor devices - the compressor consumes a starting current of three times the working one, which requires an appropriate return of your autonomous electrical system. If your motorhome is constantly connected to an external 220V network, this feature can be neglected.
- Not autonomy. Not able to work on gas in the absence of electricity.
- The complexity of the design. There are moving parts. From this and a high probability of breakdown.
- Sensitive to voltage drops in the network.
- The refrigeration unit with a highly fluid refrigerant is sensitive to shaking, vibrations and shock loads during movement.
- Keeps working capacity when tilting no more than 30 °.
Compressor refrigerators (freezers) due to their performance and efficiency today are the most widespread. In the home and at work. Also available models of compressor refrigerators for motor homes, boats and yachts from the company Dometic / Waeco, which you can purchase in our store Retrailer.
Compressor refrigerators (freezers) operate with a constant temperature in the cooled chamber from + 4 ° C to - 18 ° C.
Electricity. Voltage: 12/24 / 220V.