The absorption chiller uses which of the following to provide cooling?

• A. Heat
• B. Electrical energy
• C. Water
• D. Refrigerant

Answer: (A)

Absorption cooling is driven by heat input. In this type of system, a heat source (like steam, hot water, or gas) provides the energy to drive the cycle. The evaporator absorbs heat from the space to be cooled, causing the refrigerant (often water in a LiBr-water pair) to evaporate at low pressure and take heat from the space. The vapor is then absorbed by the absorbent, releasing heat to the absorber. To keep the cycle going, heat is added to the generator to desorb the refrigerant from the absorbent, allowing it to condense and repeat. Because the cooling effect comes from extracting heat via this heat-driven cycle, the energy source is heat rather than electrical energy, a principle that distinguishes absorption chillers from traditional electric-driven vapor-compression systems.