Absorption Machines use thermal energy (steam, hot water, …) as their primary energy source. Mechanical or electrical energy is only required for a couple of small pumps which usually consume about 1% of the cooling load.
1. In the evaporator, the liquid refrigerant is colder than the incoming water: it captures the heat from it until it evaporates.
2. In the absorber, the refrigerant vapor is captured by the LiBr solution. It returns to the liquid state and dilutes the LiBr solution (which then loses its absorption capacity). The heat of absorption is released in the LiBr solution, which in turn transfers it to the cooling fluid.
3. In the generator, the heat source transfers its heat to the dilute LiBr solution. The refrigerant picks up the heat and evaporates again. The newly concentrated LiBr solution is reinjected into the absorber.
4. In the condenser, the refrigerant vapor issued from the generator gives its heat to the water which arrives in the exchanger. Thus, the refrigerant liquefies and returns to the evaporator. It captures again the heat of the water, evaporates and thus starts the loop again.