Adsorption vs. Absorption Chillers: Applications and Use Overview

Industrial chillers are refrigeration systems that are based on two chiller technologies - adsorption and absorption. While both are advantageous in providing high-quality air conditioning, they differ widely based on their size, construction, working principle, as well as application. Adsorption chillers are purely hot water driven, whereas absorption chillers are driven by hot water, steam, or combustion. There have been many recent innovations in the development of both adsorption and absorption chillers, typically a reduction in their size, complex construction, volume, and weight.

Adsorption chillers work on the principle of adsorption using solid sorption materials such as silica gel and zeolites. These types of chillers are known for their robust construction, ease of installation, and in many cases, considered more advantageous than absorption chillers. There are no possibilities of crystallization, corrosion, hazardous leaks, and the electricity consumption is minimal. This makes them ideal for use in commercial as well as industrial air conditioning, process cooling, and waste heat recovery applications.

The absorption type of chillers is the most common source of commercial climate control and industrial machinery cooling. They use a solution containing water and lithium bromide salt to absorb heat from the surroundings. Since there is no use of CFC's or ammonia, the cooling process is environment friendly. Both adsorption and absorption types of chillers are connected through a network to chilled ceilings or fan coils in room installations.

Apart from the technology used, various other parameters differentiate an adsorption chiller from an absorption chiller. The typical cooling capacity of an adsorption chiller ranges from 5.5 to 500 KW, whereas the cooling capacity of an absorption chiller ranges from 4.5 KW to 5 MW. Adsorption chillers use butterfly valves for simpler operations, while absorption chillers use 3-way control valves.

Advantages of Adsorption Chillers:

  • No crystallization, corrosion, hazardous leaks, or chemical disposal issues
  • Low operational costs and maintenance
  • Only minor service required, 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 for hot, cool and cold water

Advantages of Absorption Chillers:

  • Most distributed chillers worldwide
  • Efficient as gas turbines produce electricity
  • Driven by hot water and hence advantageous than conventional air conditioners
  • No CFC’s or Freon

Absorption Chillers Vs Adsorption Chillers – Which is Better?

Though absorption chillers are more efficient, their lifetime (7 to 9 years), complexity, high maintenance time, and low corrosion protection are some constraints. Conversely, adsorption chillers are highly reliable with a chiller life expectancy of more than 30 years. The following table illustrates the advantages of adsorption chillers over absorption chillers.

FACTORS
ADSORPTION CHILLERS
ABSORPTION CHILLERS
Corrosion Protection
Not Required
High Corrosion Protection Required
Crystallization
No Crystallization
Very High
Inhibitor
Not Required
Heavy Metal Inhibitors
Life Expectancy
Greater than 30 Years
7 to 9 Years
Complexity
Simple, Easy Mechanical Operation
Complex, Chemical Operation
Replacement Requirements
Not Required
Heat Exchangers, Boilers, Absorbent Replacement Required
Temperature
Down to 122°F
Shut down at 180°F, Needs Back-up Heater
Chilled Water Output
40°- 55°F
48°F or More
Comparison of Adsorption Chillers vs Absorption Chillers

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