Which substances are used in an absorption refrigeration cycle?

In an absorption refrigeration cycle, ammonia and hydrogen are indeed commonly used. This cycle operates on the principle of absorption and utilizes a refrigerant, in this case, ammonia (NH3), which has excellent thermodynamic properties for refrigeration. The hydrogen in the system serves as a carrier gas that helps to maintain the pressure balance within the system.

The absorption refrigeration cycle typically involves an absorbent, which, when combined with the refrigerant, helps to create the cooling effect. Ammonia is absorbed by water or another absorbent, and once the refrigerant is evaporated (in a low-pressure evaporator), it creates a cooling effect. The absorbed refrigerant is then desorbed in a generator with the help of heat, allowing the cycle to repeat.

This process is commonly utilized in applications such as gas refrigerators and certain HVAC systems where electricity is less accessible or efficient. The use of ammonia and hydrogen is favored due to the efficiency and effectiveness of these substances in heat absorption and transfer.