Solar Air Conditioning: the Adsorption Cooling System

Solar powered air conditioning is an attractive idea of utilizing solar energy, which is the major component of a building’s cooling load. The system could eliminate or reduce conventional electric-powered air conditioning thus provide us with free energy system to a building.

In the previous editorial we have discussed on the other type of solar air conditioning, which is the absorption cooling. There are only few manufacturers produce solar air conditioning, where most of them produced using the concept of absorption cooling. Readers should not be confused between absorption and adsorption cooling. Adsorption cooling is more innovative process and has several benefits comparing to the absorption cooling.

The applications for absorption or adsorption cooling are not only limited to air conditioning system. Both cooling methods are also could be applied for chiller or any cooling systems.

Benefits of Adsorption Solar Air Conditioning

solar thermalAbsorption type of cooling system is the most common applications today for solar powered commercial climate control and industrial cooling system.

It uses solution containing water and lithium bromide salt to absorb heat from the surroundings. There is no CFCs, HCFC or ammonia, where it generates eco friendly cooling process. Nevertheless adsorption type of cooling is much better than the absorption cooling.

Absorption solar air conditioning system involves difficult to handle fluids such as ammonia or aqueous lithium bromide, as well as complicated system components. On the otherhand adsorption cooling is simpler, smaller, and cheaper to operate than absorption systems. The refrigerant of adsorption cooling or air conditioning is only water, instead of the hazardous refrigerants use in absorption systems.

Problems which exist in absorption cooling is minimize in adsorption cooling. For instance, corrosion, crystallization, hazardous leaks and the almost no electricity is needed. Adsorption air conditioning systems are practically maintenance free because of fewer parts in the whole system. The service life of adsorption air conditioning system is at least 20 years, where normally could be higher than that. Some expertise suggested even greater than 30 years.

Benefits of Adsorption Air Conditioning System

  • No corrosion, crystallization, hazardous leaks or chemical disposal issues
  • Small operational costs and maintenance
  • Need only minor service, roughly once every 3 years
  • More than 30 years of machine life
  • Low carbon emissions, eco friendly operations
  • No vibration or noise
  • Simple and continuous operations
  • Operates over a wide range of temperature either for hot, cool and cold water

Benefits of Absorption Air Conditioning System

  • Most distributed solar air conditioning system/ cooler worldwide
  • Efficient as gas turbines to produce electricity
  • Driven by hot water and thus more beneficial than conventional air conditioners
  • No CFC, HCFC or Freon

Comparison between Absorption and Adsorption Air Conditioning Systems

Regarding the cooling capacity adsorption cooling is less than the absorption system.

  • Typical cooling capacity of an adsorption cooler or air conditioner ranges from 5.5 to 500 kW
  • Typical cooling capacity of an absorption cooler or air conditioner ranges from 4.5 kW to 5 MW

Adsorption air conditioning system use butterfly valves for easier operations, while absorption air conditioning system uses 3-way control valves.

Absorption vs. Adsorption Cooler/Air Conditioner



Corrosion Protection

Not Required

High Corrosion Protection Required


No Crystallization

Very High


Not Required

Heavy Metal Inhibitors





More than 30 Years

7 to 9 Years


Simple, Easy Mechanical Operation

Chemical Operation, Complex

Replacement Requirements

Not Required

Heat Exchangers, Boilers, Absorbent Replacement Required


Down to 122°F

Shut down at 180°F, Needs Back-up Heater

Chilled Water Output

40°- 55°F

48°F or More




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2 thoughts on “Solar Air Conditioning: the Adsorption Cooling System

  1. To whom it may concern, I would like more information on the adsorption system and how it works. I have a customer who would be interested in a Solar Air Conditioner and Solar Hot water heaters.

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