Absorption chillers
Absorption chillers transform waste heat into cooling energy. An advanced solution for air conditioning large volumes (industries, hospitals, nursing homes, shopping centers), with zero emissions and maximum savings.
What are absorption chillers
Absorption chillers (water-lithium bromide), also known as lithium bromide absorbers (absorption chillers), are thermodynamic refrigeration machines used both in industrial applications for process cooling and in HVAC-R systems.
The main characteristic of an absorber is the absence of a mechanical compressor: the cycle is driven and maintained by an external thermal energy source. This particular operation is also called thermal compression as it generates the pressure differential necessary for the circulation of the refrigerant fluid, which in the case of Water-LiBr absorbers is water vapor.
The refrigerant fluid used is therefore water, a natural and safe solution characterized by GWP = 0 (Global Warming Potential).
Lithium bromide absorption chillers can be powered by various heat sources, including: hot water, superheated water, steam, flue gases. Energy carriers derived from cogeneration, industrial heat recovery, biomass, district heating, solar thermal energy. The use of these energy sources makes it possible to exploit waste heat or thermal energy available in industrial processes, improving the overall efficiency of the systems.
Lithium bromide absorbers are also available in absorption heat pump (Absorption Heat Pump AHP) version, with two different operating modes:
- Type I, used to increase the amount of heat for heating purposes;
- Type II, used to raise the temperature of a hot water source and recover thermal energy.
Thanks to their technology, absorption chillers represent a particularly effective solution for cooling large spaces, industrial plants, and production processes, where a waste heat source is available.
The main advantages of this technology are:
- Energy (and economic) savings: thanks to reduced electrical consumption compared to traditional chillers.
- Environmental sustainability: thanks to the absence of fluorinated refrigerant gases, zero GWP, and the possibility of using waste or renewable thermal energy.
- Low noise: thanks to the absence of compressors and other moving parts, vibrations and noise are minimal.
Remote control, assistance, and training
How an absorption chiller works
The fundamental condition for using water as a refrigerant is high vacuum inside the machine. The process is divided into four main phases that occur inside heat exchangers operating at two different pressure levels.
Absorption chillers are divided into 2 types: single-effect and double-effect
The differences concern the construction of the units:
- Single-effect: There is only one generator where heat separates the refrigerant from the absorbent solution.
- Double effect: Uses two generators (one high-pressure and one low-pressure). The heat supplied to the first generator produces steam which, by condensing, provides heat to the second generator. In this way, internal energy is "reused" to produce additional refrigerant.
And are reflected in performance:
- Single-effect: Has a COP (Coefficient of Performance) typically between 0.7 and 0.8. This means that for every kW of heat input, you obtain 0.7 or 0.8 of cooling.
- Double-effect: Is much more efficient, with a COP that can reach 1.2 - 1.4. In practice, it almost doubles the output for the same energy expenditure.
The choice between one technology or the other depends on the temperature of the available heat source:
- Single-effect: Works with low temperatures. It can operate with hot water at 80-90°C (ideal for solar thermal panels or industrial waste heat).
- Double-effect: Requires much higher temperatures, typically above 140-150°C, often supplied in the form of high-pressure steam or through direct gas burners.
Evaporation (Cooling Generation)
In the low-pressure section, the refrigerant water (green circuit), coming from the condenser, is sprayed onto a tube bundle where the water to be cooled circulates inside the tubes. Thanks to the high vacuum maintained in the machine, the water evaporates at a very low temperature (approximately 4-5°C). To evaporate, it extracts heat from the water circulating in the system tubes, cooling it (typically to 7°C) for final use in air conditioning.
Absorption
The water vapor produced in the evaporator migrates to the absorber. Here it comes into contact with a concentrated lithium bromide solution (brown circuit). The salt, being extremely hygroscopic, absorbs the vapor transforming it into liquid. This process releases heat, which is dissipated through an external cooling circuit, usually an evaporative tower or dry cooler (blue circuit).
Regeneration (Heat Input)
The lithium bromide solution, now diluted by the absorbed water (orange circuit), is pumped to the generator (in the high-pressure section). Here heat is supplied from outside in the form of hot water, steam, or flue gases (yellow circuit). The heat boils the solution, separating the water from the lithium bromide again:
- The water returns to vapor state.
- The salt reconcentrates and returns by gravity to the absorber.
Condensation
The water vapor generated in the previous step arrives in the condenser (blue circuit). Thanks to heat exchange with water from the cooling tower, the vapor returns to liquid state. The water thus obtained is sent back to the evaporator through an expansion valve to restart the cycle.
In AHP (Absorption Heat Pump) versions, the temperatures involved are different and the cooling/condensation circuit (blue circuit) is used to supply the high-temperature service (up to 120°C with Type II AHPs).
Advantages of absorption chillers
Energy savings
absorption chillers reduce electrical consumption as they are driven by thermal energy. They allow industry to use electrical energy for purposes other than air conditioning.
Economic savings
Absorbers, using waste heat, significantly reduce the energy costs of the facilities where they are installed.
CO2 reduction
Absorption chillers, using waste energy from thermal recovery, help reduce CO2 emissions by reducing the carbon footprint of the facilities where they are installed.
environmental sustainability
With a GWP=0, absorption chillers do not use climate-altering gases. In this way they do not release greenhouse gases, contributing to the protection of the environment and atmosphere.
Low noise
Absorbers, having no moving parts such as compressors and fans, are extremely quiet and have no impact on acoustic comfort in installation areas.
Reliability and long life
The absence of mechanical compressors and the use of hermetic pumps only reduce the risk of downtime due to failure, significantly extend the useful life of the system, ensuring service continuity.
Maximum flexibility
The modulation range from 10% to 100% allows the absorber to adapt to the applied load, ensuring high performance and optimal efficiency.
Access to energy incentives
The efficiency in thermal energy use allows benefiting from incentive instruments such as Energy Efficiency Certificates (TEE) or the Thermal Account.
Reduced operating costs
Thanks to the simplicity of components and high efficiency, overall operational and maintenance expenses are lower compared to other traditional air conditioning systems.
Renewable energy, thermal recovery, and trigeneration
Trigeneration
Combined production of electrical, thermal, and cooling energy. A high-efficiency solution that enables rational use of primary energy and a significant reduction in polluting emissions, where the use of the absorber allows the use of thermal energy also in the summer period.
District heating
Allows improving the return on investment by enabling the system to produce also in the summer period for building air conditioning. In heat pump version they are used to recover heat from the thermal power plant activity and increase district heating efficiency.
Thermal recovery from processes
Absorbers recover residual heat from industrial processes, which is normally dispersed into the environment, transforming it into cooling energy useful for cooling new processes, technical rooms with electrical components, or for conditioning work environments.
Use of biomass
Absorbers valorize heat produced from solid biomass, biogas, syngas, and agricultural, livestock, and forestry by-products, transforming it into useful cooling energy, allowing the use of solid biomass also in the summer period.
Who it is suitable for
Industrial (Air conditioning)
absorption chillers are ideal for air conditioning industrial environments where waste heat is available from production processes, cogeneration, or renewable thermal sources. They allow this heat to be transformed into cooling, reducing electrical consumption and emissions. Ideal for manufacturing companies, chemical plants, petrochemical facilities, steel mills, and power generation plants, where thermal stability and efficiency are essential.
Industrial (Production processes)
In production plants, especially those with intense thermal phases (e.g., food industry, metal processing, glass, cement, chemicals), absorbers offer continuous and reliable cooling by exploiting waste heat sources. This translates into significant savings on operating management costs.
Hospitals / Nursing homes (Air conditioning)
Absorption chillers are perfect for air conditioning hospital and nursing home environments where heat is available from cogeneration or district heating. They allow transforming this heat into cooling, reducing electrical consumption and emissions. Ideal for all facilities that cannot interrupt air conditioning and need to have multiple solutions serving the same purpose.
Shopping centers (Air conditioning)
Absorbers are perfect for air conditioning shopping centers where heat is available from cogeneration or district heating. They allow transforming this heat into cooling, reducing electrical consumption and emissions. Ideal for all facilities that need medium-large cooling capacities but want to contain management costs.
Lithium bromide absorption chillers
A complete range of absorbers, designed to adapt to different industrial, process, and air conditioning needs, ensuring energy efficiency, reliability, and sustainable use of resources.
Absorption Chillers vs. Electric Compression Chillers
Absorption chillers
Electric compression chillers
Remote Management of Absorbers
Thanks to the dedicated supervision system, you can monitor and remotely manage the operation of absorbers with complete autonomy, even via mobile devices.
Through a simple internet connection it is possible to turn units on and off, set operating parameters, monitor their performance in real time, and schedule any maintenance. An intuitive interface also allows analyzing consumption data and efficiency, optimizing system performance and reducing management costs.
Case Studies and Testimonials
Absorption chiller FAQ
Do you want to better understand how absorbers work and what benefits they can bring to your company? Here you will find answers to the most frequently asked questions, explained clearly and directly.
An absorption chiller is a refrigeration machine that produces chilled water by exploiting a heat source rather than an electric compressor.
It is advisable to choose a lithium bromide absorber when a heat source is available from renewable sources, thermal recovery, solar thermal, cogeneration, or district heating.
The absorber represents a greener and more sustainable choice, useful for contributing to environmental protection.
Absorbers cover a power range from 50 kW to 10 MW.
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: steam is produced in the generator, which after being condensed in the condenser enters the evaporator. In the evaporator, chilled water is produced thanks to the evaporation of the refrigerant (water). The steam created in the evaporator then enters the absorber and is absorbed by the lithium bromide solution.
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. It is one of the main strengths of absorbers: they can be powered with waste heat from industrial processes, cogeneration engines, biomass plants or waste-to-energy plants, and flue gases from production processes. They can also exploit 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.
Unlike traditional chillers, absorbers do not use climate-altering refrigerant gases, but only water as refrigerant fluid. This means drastically reduced CO₂ emissions and minimal environmental impact. Furthermore, by exploiting waste heat or renewable sources, the absorber contributes concretely to the decarbonization of industrial processes and the energy transition.
