Teaching Aids and instructional materials

Refrigerator as a Teaching Aid

A refrigerator is an essential household appliance used to keep food and beverages cool and fresh. The basic principle of a refrigerator involves the removal of heat from the interior to the exterior environment, thereby lowering the temperature inside the unit.

The refrigeration cycle consists of four main components: the compressor, condenser, expansion valve, and evaporator. The process begins with the compressor, which compresses the refrigerant gas, raising its pressure and temperature. The hot, high-pressure gas then flows into the condenser coils located at the back or bottom of the refrigerator, where it releases heat to the surroundings and condenses into a liquid.

Next, the high-pressure liquid refrigerant passes through the expansion valve, where it undergoes a rapid decrease in pressure, causing it to cool significantly. This cold, low-pressure liquid then enters the evaporator coils inside the refrigerator. As the refrigerant evaporates, it absorbs heat from the interior, thus cooling the air inside the fridge. The cycle then repeats as the refrigerant returns to the compressor.

By continuously cycling the refrigerant through these stages, the refrigerator maintains a consistently low temperature, preserving the freshness and quality of stored items.

Refrigeration Circuit with R134a Refrigerant

Basic Refrigeration Circuit

A refrigeration circuit is a system designed to transfer heat from one place to another, thereby cooling the interior space. This process involves four main components: the compressor, condenser, expansion valve, and evaporator.

Compressor: The compressor is the heart of the refrigeration circuit. Its main function is to compress the refrigerant, increasing its pressure and temperature. The compressed refrigerant, now in the form of a hot gas, is then sent to the condenser.
Condenser: The condenser is a device that allows the refrigerant to release heat to the surrounding environment. The hot gas from the compressor passes through the condenser coils, where it cools down and condenses into a liquid. This process releases heat, which is carried away.
Expansion Valve: The expansion valve regulates the flow of refrigerant into the evaporator. As the liquid refrigerant passes through the expansion valve, it undergoes a rapid decrease in pressure, causing it to cool significantly. This cold, low-pressure liquid refrigerant then enters the evaporator.
Evaporator: The evaporator is where the refrigerant evaporates. As the refrigerant evaporates, it absorbs heat from the interior space, thereby cooling the air inside the device. This process converts the liquid refrigerant back into a gas, which is then drawn back into the compressor, and the cycle repeats.

Refrigerant R134a

What is refrigerant R134a? Refrigerant R134a is a special gas used in refrigerators and air conditioners to keep things cool. It is a colorless gas with a very low boiling point, which means it easily changes from a liquid to a gas and back.

Basic properties:

Colorless gas: It has no color.
Low boiling point: It boils at around -26°C.
Safe for the ozone layer: It does not harm the ozone layer, which protects the Earth from harmful UV radiation.
Uses: It is used in refrigerators, air conditioners, and even some medical devices.

How does it work? Refrigerant R134a works by absorbing heat from the inside of a refrigerator or air conditioner and releasing it outside. This cools the interior space. The process repeats continuously to keep things cool.

Why is it important? Refrigerant R134a is important because it helps keep food fresh and drinks cold. It also provides a comfortable environment on hot days thanks to air conditioners.

Videos demonstrating processes

1. Vacuuming

Vacuuming the refrigeration circuit is a process where air and moisture are removed from the circuit. This step is crucial for the proper functioning of the refrigeration system, as air and moisture can cause corrosion, reduce efficiency, and lead to other issues.

2. Nitrogen Test

The nitrogen test is a procedure used to check for leaks in a refrigeration circuit. This test is important to ensure the system is airtight and functioning properly before charging it with refrigerant.

3. Refrigerant charge

Refrigerant charge is the process of adding the correct amount of refrigerant to a refrigeration circuit to ensure the system operates efficiently.

4. Refrigerant recovery

Refrigerant recovery is the process of safely removing old or unusable refrigerant from a refrigeration circuit. This step is important for the maintenance and repair of the refrigeration system.

Simulator of a Heat Pump with R290 Refrigerant

A heat pump is a device used for heating and cooling buildings. It operates on the principle of transferring heat from one place to another using a small amount of energy.

Operating Principle:

Heat Transfer: The heat pump transfers heat from the outside environment (air, ground, or water) to the interior of the building. In winter, it extracts heat from the outside air and transfers it inside, while in summer, it removes heat from the interior and releases it outside.
Compressor: The compressor compresses the refrigerant, increasing its pressure and temperature. The hot refrigerant then flows into the condenser.
Condenser: In the condenser, the refrigerant releases heat into the interior space of the building and condenses into a liquid.
Expansion Valve: The liquid refrigerant passes through the expansion valve, where it undergoes a rapid decrease in pressure and temperature.
Evaporator: The refrigerant enters the evaporator, where it absorbs heat from the outside environment and evaporates. This process repeats continuously.

Heat pumps are energy-efficient because they do not use fuel to create heat but instead transfer existing heat. This makes them more environmentally friendly.

Refrigerant R290

What is refrigerant R290? Refrigerant R290, also known as propane, is a special gas used in refrigerators and air conditioners. It helps keep things cool and is environmentally friendly.

Basic properties:

Colorless and odorless: It has no color or smell.
Low boiling point: It boils at around -42°C.
Ozone-friendly: It does not harm the ozone layer, which protects the Earth from harmful UV radiation.
Low global warming potential: It has a very low global warming potential (GWP).

Uses:

Refrigerators and freezers: Keeps food and drinks cool.
Air conditioners: Helps cool the air in rooms.
Industrial refrigeration: Used in various industrial equipment.

Why is it important? Refrigerant R290 is important because it is energy-efficient and environmentally friendly. It helps keep our food fresh and provides a comfortable environment on hot days.

More information about the simulator