Absorption Refrigerator DIY – The appearance of various types of household refrigerators marks a fairly long history of refrigeration development. A household absorption apparatus – a gas refrigerator – can be found among the existing structures.
Gas refrigerator models are available in both stationary and mobile configurations. Their simple design does not rule out the possibility of making a device with their own hands. To build a gas refrigerator, you must first understand its structure and operating principles. Do you agree?
This article details the design of the propane unit, the technical cycle of the cooling and step by step instructions on the assembly and restoration of various gas refrigerator modifications.
What are An Absorption Refrigerator
An absorption refrigerator is a refrigerator that uses a heat source (e.g., solar energy, a fossil-fueled flame, waste heat from factories, or district heating systems) to provide the energy needed to drive the cooling process.
The system uses two coolants, the first of which performs evaporative cooling and is then absorbed into the second coolant; heat is needed to reset the two coolants to their initial states.
The principle can also be used to air-condition buildings using the waste heat from a gas turbine or water heater. Using waste heat from a gas turbine makes the turbine very efficient because it first produces electricity, then hot water, and finally, air-conditioning—trigeneration.
Absorption refrigerators are commonly used in recreational vehicles (RVs), campers, and caravans because the heat required to power them can be provided by a propane fuel burner, by a low-voltage DC electric heater (from a battery or vehicle electrical system) or by a mains-powered electric heater.
Unlike more common vapor-compression refrigeration systems, an absorption refrigerator can be produced with no moving parts other than the coolants.
Propane Refrigerator Device
Refrigeration technology that can work with propane is based on the absorption principle of operation.
It is important to note that when considering the gas refrigerator and the theory of its operation, propane is assigned the minor function of a gas heater in the absorption refrigerator. Ammonia and water are usually the major components of the absorption process in the manufacturing of residential refrigerators.
Water functions as an absorbent and ammonia acts as a refrigerant.
The following process modules are included in the simplified gas model:
- Module for gas heating.
- Generator (more precisely – a boiler).
- Suppressor (absorber).
The generator’s contents are heated by the gas heater. The generator module produces vaporized ammonia and supplies a weak ammonia solution to the absorber zone.
The condenser module is used to bring ammonia vapor to a temperature where it may condense. An ammonia absorber is a module termed a “absorber.” The evaporator of the gas cooler acts as a cold generator.
The principle of the gas refrigerator
The technological cooling cycle begins with a gas burner heating a concentrated aqueous ammonia solution. Because ammonia has a lower boiling point than water, it boils faster. The process of producing concentrated refrigerant vapor, which enters the condenser, starts.
The ammonia vapor condenses here, and liquid ammonia rushes to the evaporator, where it boils as a result of heat selection from the products, forming a vapor-liquid mixture.
The absorption refrigerator circuit also controls the operation of the device known as the “reflux condenser.” This module is installed at the boiler’s outlet and is intended to produce a weak aqueous ammonia solution during partial condensation of saturated vapors.
An absorber collects this weak solution. The evaporator sends a saturated vapor-liquid ammonia mixture there, where it is absorbed. The cycle is then repeated.
Most absorption household refrigerators are equipped with electric heaters.
But it’s perfectly acceptable to replace an electric heater with any other heat source, including a propane burner, a heating radiator, and even chimney smoke.
Therefore, it is theoretically quite acceptable to use the noted models of absorption technology for the creation of a gas fridge, which operates in a constant mode, with one’s hands.
How To Make Homemade Gas Refrigerator
Absorption Refrigerator DIY – A relatively simple method of manufacturing a gas refrigerator, as already noted, is seen as the use of an exhausted absorption apparatus as the basis.
Instead of dismantled heating elements, it will be necessary to introduce gas heating by installing a heat exchanger and a propane burner in the design.
The temperature of the freezer during construction at full power may well reach 10-12 ° C with a minus sign. It was not for nothing that among the craftsmen-designers the idea was born to remake electric heating, replacing it with a propane heating pad.
However, the idea of a gas refrigerator is dubious, and there are a number of reasons to confirm this. So, the absorption process requires almost twice as much time to generate cold than a conventional compression refrigerator.
From the point of view of economy, the design does not seem to be entirely rational, given how much gas it will take to get 1 ° C below zero for a home-made version. Nevertheless, the design interest regarding the possibility of implementing the idea is quite high.
DIY Gas Refrigerator Remaking “Sadko” Refrigetaror
The electric heating elements of the Sadko refrigerator are located on the siphon tube. This structural element (siphon) is located at the bottom of the rear wall of the apparatus. The siphon area is covered by a metal casing, under which there is a layer of heat insulator (mineral wool).
Initially, an amateur designer will need to do the following:
- Place the refrigerator in a convenient place for work.
- Remove the protective cover on the rear wall.
- Remove thermal insulation material.
- Remove the heating elements from the siphon tube.
It should be borne in mind that do-it-yourself modification is associated with some risk. The absorption refrigerator system is filled with ammonia and hydrogen under pressure up to 2 atm. Careless dismantling of system parts and electric heaters can lead to depressurization of the system, which is hazardous to health. Care must be taken.
The next step of the amateur designer is to install a heating system operating on propane. That is, it is necessary to mount a module in the area of the siphon tube, which would be used for heating as a result of gas combustion. It is unacceptable to heat the tube with an open flame.
So, you need to make a heat exchanger. It can be, for example, a massive bar of copper, inside which is built gas-burner.
The manufacture of a gas heating system always includes the organization of an overheating protection complex. The operating temperature range for heating the Sadko refrigerator’s siphon is 50 – 175 ° C. Based on these values, the scheme for turning on and off the gas supply during heating must be considered.
Refrigerator thermostat T-120 series is used for a circuit with electric heaters in absorption models. However, this device regulates the operation of heaters by taking the temperature of the evaporator into account.
A system with a gas burner and an automatic control unit is slightly different. If a propane refrigerator is designed for long-term usage, the automation must be fully functional.
That is, it is possible to manage not only the heat exchanger’s heating temperature, but also the flame and the gas pressure. The system fuse must not be overlooked.
Have you ever built a gas refrigerator? Or do you rely on a commercial absorption system? Please share your thoughts and opinions. In the lower block, there is a contact form.