24/05/2023
Three way refrigeration, a look inside.
A 3-way fridge, also known as an absorption refrigerator, is a type of refrigerator that can operate using three different energy sources: electricity, liquid propane (LP) gas, and 12-volt battery power. It is commonly used in recreational vehicles (RVs), campers,
and off-grid locations where multiple power options are available.
The basic working principle of a 3-way fridge involves a combination of heat, pressure, and chemical reactions. Here's an overview of the process:
Heat Source: The fridge requires a heat source to function. The three available options are electricity, LP gas, and battery power. The selected heat source determines how the fridge
operates.
Absorption Process: The heart of the 3-way fridge is the absorption system, which consists of a closed-loop system containing a mixture of chemicals, primarily ammonia, hydrogen
gas, and water. The chemicals are contained within a series of interconnected tubes and chambers.
Ev***rator: The ev***rator is located inside the fridge compartment and is responsible for cooling the interior. It consists of a set of metal fins or coils that are in direct contact
with the items to be cooled.
Condenser: The condenser is located outside the fridge and is responsible for dissipating heat from the system. It consists of a set of metal fins or coils that help transfer heat
to the surrounding environment.
Expansion: The absorption system relies on the expansion of ammonia gas to create a cooling effect. When the ammonia gas expands, it absorbs heat, causing the surrounding environment
to cool down.
Now, let's look at how the 3-way fridge operates with each heat source:
Electricity: When connected to an electrical power source, the fridge uses an electric heating element located at the bottom of the absorption system. This heating element provides
the necessary heat for the absorption process. The electricity powers the heating element, which warms up the ammonia mixture, causing it to v***rize. The ammonia v***r then rises to the condenser, where it cools down and turns back into a liquid state. The
liquid ammonia then flows to the ev***rator, where it ev***rates, absorbing heat from the interior of the fridge, thus cooling it. The cycle continues as the ammonia v***r returns to the absorber, and the process repeats.
LP Gas: When using LP gas, the fridge utilizes a gas flame as the heat source. The flame is ignited by a pilot light or an electronic ignition system. The gas flame heats a section
of the absorption system called the boiler, which causes the ammonia mixture to v***rize. The rest of the process is similar to the electricity-powered mode, where the v***rized ammonia rises to the condenser, cools down, turns back into a liquid, and flows
to the ev***rator to cool the fridge's interior.
Battery Power: In battery mode, the fridge employs a 12-volt heating element similar to the one used with electricity. The heating element warms up the absorption system, causing
the ammonia mixture to v***rize, and the subsequent cooling process follows the same steps as with electricity or LP gas.
It's important to note that the heat generated from the selected heat source, be it electricity, LP gas, or battery power, is what drives the absorption process, allowing the fridge to cool its interior.
Overall, a 3-way fridge provides flexibility in power sources and allows users to operate it using the most suitable energy option available to them.
