Many owners of country real estate and avid travelers wonder how a refrigerator runs on gas, since this technology is radically different from conventional household models. Unlike standard kitchen units, where the main engine of the cycle is a noisy compressor, this uses the principle of absorption, which does not require electricity to create cold. This makes such devices ideal for places where there is no reliable power supply, or for self-contained motorhomes.
The process is based on the circulation of a refrigerant, usually ammonia, inside a sealed system of tubes filled with an inert gas. Absorption refrigerator has no moving mechanical parts, which ensures virtually silent operation and a long service life. Understanding the physics of this process will help you operate the equipment correctly and avoid common mistakes during installation.
The uniqueness of the design lies in the fact that the heat obtained from the combustion of gas is used to separate the components of the mixture and create the pressure necessary for condensation of the refrigerant. Gas refrigerator is able to maintain a low temperature even at full lack of electricity, which is its main trump card in wild conditions or frequent power outages in rural areas.
The principle of operation of the absorption system
The fundamental difference from compressor models lies in the way the refrigerant circulates. There is no engine compressing the gas; instead, a heat pump is used. An ammonia-water solution circulates in the system, where ammonia acts as a refrigerant and water as an absorbent. Heating elementoperating on gas, brings the solution to a boil in the generator, causing the evaporation of ammonia.
After the vapor evaporates ammonia under high pressure enters the condenser, where it cools and turns into a liquid state. Next, the liquid refrigerant enters the evaporator located inside the refrigeration chamber. There, mixing with hydrogen, it boils at a very low temperature, actively removing heat from the interior of the chamber. It is this process absorption that creates the necessary cold.
⚠️ Attention: Ammonia circulates in the system under pressure. Despite the small amount of the substance, independent repair of tubes or welding of the body is strictly prohibited due to the risk of explosion and toxicity.
The final stage of the cycle is the reabsorption of ammonia vapor by water in the absorber. The weak solution is heated again and the cycle repeats. It is important to understand that absorption refrigerator works continuously as long as heat is supplied, since interrupting the cycle at any stage can upset the pressure balance in the entire system.
Why is ammonia used?
Ammonia has excellent thermodynamic properties and is capable of boiling at very low temperatures (-33°C) at atmospheric pressure, which makes it an ideal refrigerant for systems without a compressor.
Key components of a gas refrigerator
The design of the device looks more complex than that of a conventional refrigerator due to the presence of a heat exchanger system and a burner device. The main unit is generatorwhere the ammonia-water mixture is heated. This is where a gas burner or electric heating element is installed in combined models. The quality of heating directly affects the efficiency of the entire cycle.
Then the vapors enter the reflux condenser - a special heat exchanger, where partial condensation of water vapor occurs so that it does not enter the evaporator. Pure ammonia moves on to a condenser, which is usually a finned coil on the back of the device. Here heat is released to the environment.
Inside the refrigeration chamber there is evaporatorwhere liquid ammonia is mixed with hydrogen. Hydrogen is needed to create the partial pressure that allows ammonia to boil at low temperatures. After evaporation, the mixture of gases returns to the absorber, where water again absorbs ammonia, completing the cycle of substances.
| Component | Function | Location |
|---|---|---|
| Generator | Heating the mixture and evaporating ammonia | Lower part of the housing (rear) |
| Condenser | Cooling and liquefaction of vapors | Rear grille |
| Evaporator | Creating cold inside the chamber | Inside the freezer compartment |
| Absorber | Ammonia vapor absorption water | The lower part of the system |
All these elements are connected by thin steel tubes filled with an inert gas (usually hydrogen or helium). The tightness of this system is the key to a long life of the device. Any microcrack will lead to failure of the device, therefore gas refrigerators require careful handling during transportation.
Security systems and automation
The use of open fire or hot elements inside a living space requires their safety measures. Modern models are equipped with a system gas control. This device automatically shuts off the gas supply if the flame goes out for any reason, for example, due to a draft or lack of draft.
The operating principle of the gas control is based on a thermocouple. While the flame heats the tip of the thermocouple, an electric current is generated in the system, which keeps the solenoid valve open. If the fire goes out, the thermocouple cools, the current disappears, and the spring instantly closes the valve. This prevents the leakage of natural gas or propane into the room.
⚠️ Attention: Never ignore the clicks of the gas control valve when igniting. Keep the regulator knob pressed for 10-20 seconds after ignition so that the thermocouple warms up and locks the valve.
In addition, many models have overheating protection and draft sensors. If combustion products are not removed effectively, the sensor may block the burner. Combined models (gas/220V) also have automatic switching of energy sources, which ensures continuous operation without human intervention.
Advantages and disadvantages over compressor models
The main advantage of absorption refrigerators is their complete energy independence from electricity. They can work for days on one propane tank, which is critical for long trips to the country or to a campsite. The lack of vibration and noise makes them ideal for bedrooms in motorhomes or small studios.
However, the technology also has its limitations. Absorption cycle less efficient than compressor technology. This means that more energy is required to reach the same temperature and the cooling process takes longer. In addition, such refrigerators are sensitive to tilting: they cannot be tilted too much during operation, as this disrupts the circulation of the mixture.
- 🔇 Completely silent operation - no compressor hum.
- ⛽ Possibility of operation from bottled gas or network 220V and sometimes 12V.
- 📉 Lower energy efficiency compared to classic models.
- ⏳ Long time to reach operating mode after switching on.
Another nuance is the dependence on the ambient temperature. If it's very hot outside, the condenser's heat transfer efficiency drops and the refrigerator may stop freezing. Therefore gas models often require installation in well-ventilated niches with access to fresh air.
Operation and ignition rules
Starting the refrigerator requires following a certain sequence of actions. First you need to make sure there is gas in the cylinder and check whether the valve on the pipeline is open. Then you should open the window or ensure the room is ventilated in case of leakage during the first start-up.
The ignition process usually begins by bringing a fire (match or piezoelectric element) to the igniter and simultaneously pressing the gas supply button. After the wick lights up, you must hold the button for 10-30 seconds. This is necessary to warm up the thermocouple. If you release the button too early, the security system will shut off the gas.
Ignition sequence:1. Open the valve on the cylinder.
2. Press and hold the gas supply regulator.
3. Light the igniter.
4. Hold the regulator for 20 seconds.
5. Release and check the stability of the flame.
After successful start-up, the flame should be smooth and blue. Yellow or orange flames indicate incorrect settings or contamination of the burner. The power is adjusted by turning the thermostat knob, which changes the intensity of the gas supply to the burner.
☑️ Check before first switching on
Typical faults and diagnostic methods
Despite the simplicity of the design, sometimes problems arise with cooling. The most common cause is a clogged circulation system. During long-term operation, plugs from corrosion products or salt crystallization may form in the tubes. This blocks the movement of the mixture, and the refrigerator stops cooling, although the burner is working properly.
Another common problem is a leak. If you smell ammonia (a strong, specific odor) near your running refrigerator, there is a leak. This device cannot be used. Also, a sign of depressurization may be the appearance of yellow spots or crystals on the system tubes.
⚠️ Attention: If the refrigerator makes gurgling sounds after turning off, this is normal (the mixture is overflowing). But if the gurgling is loud and constant during operation, there may be an air lock in the system or a lack of refrigerant.
For diagnostics, it is also worth checking the burner. If it smokes or the flame comes off, you need to clean the nozzle. Often dust or cobwebs get into it, especially if the refrigerator has been sitting idle for a long time. Cleaning should be carried out only after complete cooling and shutting off the gas.
Frequently asked questions (FAQ)
Why does a gas refrigerator take a long time to gain temperature?
The absorption process is inert in nature. Unlike a compressor, which creates cold quickly, the system requires time (from 4 to 12 hours) to stabilize the circulation of the mixture and reach the minimum temperature. This is a standard characteristic of the technology, and not a breakdown.
Is it possible to transport a gas refrigerator lying down?
It is strictly not recommended. When transported in a horizontal position, liquid from the system may flow into the gas part of the circuit or the hydrogen balance may be disrupted. If transportation lying down was unavoidable, the device must stand upright for at least 24 hours before turning it on.
What is the gas consumption of such a refrigerator?
The average consumption of a propane-butane mixture is about 250-350 grams per day at full load and an ambient temperature of +25°C. One standard 50-liter cylinder is usually enough for 2-3 weeks of continuous operation.
Why is the back wall of the refrigerator hot?
This is normal. In absorption refrigerators, the heat taken from the chamber plus the heat from gas combustion must be released to the external environment. Therefore, the condenser grille on the rear wall heats up much more than that of conventional refrigerators.