What is Absorption Chiller

Flue Gas Operated Absorption Chiller

In contrast to typical chillers, absorption chillers use waste heat from other processes or equipment to drive a thermodynamic process that allows water to be chilled and distributed for HVAC needs. In place of conventional refrigerants, water is often coupled with either ammonia or lithium bromide, with lithium bromide being the more preferred option because to its non-toxicity. 

Important factors 

Because absorption chillers do not require electric compressors, they may provide significant cooling capacity while contributing to peak energy consumption. The most crucial element to consider when assessing the use of such a chiller is that they do need a significant and consistent source of waste heat to function. Although industrial manufacturing facilities are the most obvious candidates, other places like as university campuses, larger hospital complexes, or large hotels may also benefit considerably from the addition of an absorption chiller. 

The advantages of using absorption chillers 

The principal refrigerants used in absorption chillers have no negative effects on global warming or ozone depletion. An absorption chiller might assist the business in saving money on electricity, hot water, heating, and cooling. The lack of compressors in the machine decreases noise and vibration in the building, resulting in a tranquil environment with high reliability. 

An absorption chiller is nearly entirely powered by heat that would otherwise be squandered. It does not need energy to generate chilled water or heat. A considerably larger capacity will not be required in an emergency backup power system. 

The Science of Absorption Chilled Water 

A condenser, generator, evaporator, absorber, and heat exchanger are all part of an absorption chiller. Initially, the absorber contains the refrigerant or lithium bromide water. It will be driven into the generator tank on the top of the chiller through the heat exchanger. The chiller’s generator will use solar heat or waste steam from other systems. Lithium bromide and water are separated by heat. Water evaporates slowly and rises to the condenser, while lithium bromide sinks. 

A conduit will carry the lithium bromide back to the absorber. The vapor will next pass via a cooling tower. The air pressure in the cooling tower pipe is lower than in the condenser. When the air pressure drops, water condenses. The cold water is then evaporated and re-mixed with lithium bromide. 

An absorption chiller, in a nutshell, cools water by quickly changing pressure. As the water in the generator warms up, the air pressure rises. Water vaporizes when it loses heat. The vapor is then sent to the evaporator to cool. The vapor swiftly cools and condenses to become cold water. Heat is absorbed by vapor, which then condenses to form water. 

When water evaporates, it absorbs heat. In a low-pressure environment, the vapor cools and returns to water. The water in the absorber reacts with the lithium bromide and returns to the heat exchanger, carrying with it undesired heat. 

With low energy input, an absorption chiller generates cooled water. Throughout the heating and cooling cycles, it will continue to remove heat from the structure. 

Working concept 

To describe the technique, let’s start with the generator. A condenser, absorber, and evaporator are all part of this chiller. This process produces a liquid refrigerant solution that can be pushed to greater pressures. This pumping method is used to replace mechanical compression that is powered by electricity. 


Pour in the heated, diluted solution. On a heat exchanger that carries hot water or another source of heat. When the solution boils, it produces refrigerant vapor as well as a hot concentrated solution. 


Once in the condenser, the vapor is converted back into a liquid via a colder heat exchanger. The liquid refrigerant can reach the evaporator thanks to a temperature and pressure reduction expansion valve. 


Low-pressure refrigerant is introduced as a mixture of liquid and vapor. This area is designed to help you unwind. The evaporator chills water for cooling in commercial buildings. 


The refrigerant enters the absorber after passing through the evaporator. The absorber absorbs the refrigerant vapor and dilutes it. The heat generated is dissipated by the cooling water. 

Absorption chillers Utilization 

While absorption chillers outperform conventional cooling systems in the areas we’ve just addressed, proper and regular maintenance is essential for best performance. This is the only way to ensure that the equipment will endure the whole 25 years. A chiller will run perfectly if maintenance staff focus on the following areas: controls, mechanical components, and heat transfer components. 

Here are a few examples of issues that need to be addressed: 

  • Inspect pump shaft seals for wear. • Check for refrigerant leaks. The loss rate should not exceed 1%. 
  • Heat transfer surfaces must be clean and sludge and scale free. 
  • Heat exchanger tubes should be free of cracking, pitting, and corrosion. 
  • Pump bearings may need to be repaired or cleaned. 

Absorption Chiller Selection 

Even if you use all of the recommended maintenance measures, the equipment will deteriorate, and your maintenance costs will climb. That might be the time to upgrade to more modern, durable, and efficient equipment. If the system is working at part load for a lengthy period of time, a chiller with high part load efficiency may be all that is needed. It is also vital to size the chiller correctly. A chiller that is too big for a certain application will almost definitely operate inefficiently. If exposed to such stresses over an extended length of time, it may develop serious problems. A detailed evaluation of operational requirements, facility type, and timetable should be used to establish the chiller upgrade/selection procedure. 

Advantages of absorption chillers 

Advantages of absorption chillers (Source: Shuangliang)

It was briefly discussed at the opening of this article. The following are scenarios when absorption chillers would be favored, according to the concept of absorption chiller functioning and demands. 

  • Expensive electricity and inexpensive gasoline  
  • Check to see whether the change is substantial enough. 
  • There isn’t enough electricity. 
  • Waste heat is provided (for example from exhaust flow or hot water from engine jacket). 
  • A adequate supply of hot water or low-grade waste steam. 

It will also fit in situations where a quiet environment is required — an absorption chiller is a silent, wear-free system due to the lack of moving components — and needs no maintenance. 

How to Install an Absorption Chiller 

It is best to work with a contractor that is familiar with sophisticated systems like absorption chillers. Experts can help you design, install, and finance an absorption chiller system that makes financial sense for your company and has a clear path to delivering a fair return on investment. 

Apart from its equipment and units that combine into LNG process or LNG storage system, one of the most important part of the system is the connection between each unit and each section. Of course, in the Oil & Gas business or in the petroleum business we use steel pipe as the main transportation means and as the linkage between modules.