Absorption Chiller FAQ
Absorption chillers, also known as absorbers, represent a strategic solution for producing cooling energy by utilizing heat sources, including waste heat. Here you will find answers to the most frequently asked questions about how they work, when it is advantageous to choose them over compression chillers, and how they integrate into existing systems.
An absorption chiller is a refrigeration machine that produces chilled water by utilizing a heat source rather than an electric compressor. The system operates with two fluids: water and lithium bromide. The absorber is particularly suitable when low-cost or waste heat is available (cogeneration, process heat, solar thermal), allowing for reduced electrical consumption and indirect emissions compared to compression solutions in appropriate scenarios.
The operating principle of the lithium bromide absorber is based on the principle of evaporation using an external heat source to supply energy. In summary: vapor is produced in the generator, which after being condensed in the condenser enters the evaporator. In the evaporator, chilled water is produced through the evaporation of the refrigerant (water). The vapor created in the evaporator then enters the absorber where it is absorbed by the lithium bromide solution.
The choice is advantageous when there is an economical or free heat source (heat recovery, cogeneration, district heating, solar thermal) and the cooling load profile is significant and regular. The absorber represents a greener and more sustainable choice, useful for contributing to environmental protection.
Unlike traditional chillers, absorbers do not use climate-altering refrigerant gases, but only water as the refrigerant fluid. This means drastically reduced CO₂ emissions and minimal environmental impact. Furthermore, by utilizing waste heat or renewable sources, the absorber contributes concretely to the decarbonization of industrial processes and the energy transition.
Absorbers use thermal energy as the primary source to initiate the operating cycle. They can operate with hot water, superheated water, steam, diathermic oil, solar, flue gases, geothermal, trigeneration, and with all sources that can provide heat.
Yes. This is one of the main strengths of absorbers: they can be powered by waste heat from industrial processes, cogeneration engines, biomass plants or waste-to-energy facilities, and flue gases from production processes. They can also utilize thermal energy produced by solar thermal systems. This flexibility makes the technology particularly sustainable and economically advantageous, especially in industrial contexts where unused heat is available.
Absorbers cover a power range from 50 kW to 10 MW.
Scheduled routine maintenance must be performed by technicians specialized in absorption. Generally, maintenance includes:
- monitoring and balancing the lithium bromide concentration,
- vacuum verification,
- checking the amount of dirt (e.g., mineral salt deposits) present in the tube bundle heat exchangers,
- verification of the non-condensable automatic purge system.
The term "non-condensables" refers to all gases that are present inside the absorber and are not absorbed by the lithium bromide solution. If not properly purged, these gases can reduce the absorber's efficiency.
As standard, the absorber is equipped with manual purging. It is possible to request automatic purging of non-condensables at the time of order.
Yes. There are lithium bromide absorbers called multi-energy that are specifically designed to use more than one heat source.
It depends. Generally, the use of a cooling tower is the best cost/economic choice. This does not exclude the possibility of using other methods to control the cooling water temperature. For example, dry-coolers, well water heat exchangers, etc. In certain cases, it is possible to recover the heat dissipated by the cooling tower for other uses.
Crystallization is the physical phenomenon that occurs when a solution (water-salt) becomes saturated. When a solution becomes saturated, the salt dissolved within it precipitates to the bottom of the container, forming salt crystals.
A solution is said to be saturated when adding more solute (salt) to the solution does not dissolve. The solubility of a solute is influenced by temperature. Generally, the higher the temperature, the more salt can be dissolved. The lower the temperature, the less salt dissolves.
Yes. The absorber has an automatic system that limits crystallization of the lithium bromide solution.
