Zudek's ammonia absorbers
Sustainable Technologies, Zudek Products

Zudek’s ammonia absorbers

The rediscovery of a system with more than one hundred years of history

The absorption refrigeration cycle is an invention dating back to 1859 and then developed into a refrigeration system in 1930, when Albert Einstein and his former student Leo Szilard patented for the first time a refrigeration system that had no moving parts and which only required a heat source to work.

Over the years, the discovery of synthetic gases and the development of technology led to the Nobel Prize project being put aside for almost a century.

Recently, however, new discoveries regarding the polluting potential of synthetic gases and the consequent rules that will ban these refrigerant liquids in the coming years have brought the use of natural refrigerants and, consequently, this type of technology back into vogue.

Zudek, which has been using only natural refrigerants for its products for thirty years, designed and produced its own ammonia absorber 10 years ago: Enermatik.

In today’s article we will explain how the ammonia absorption cycle works and the advantages this brings.

The ammonia absorption cycle

The absorption refrigeration cycle is a type of refrigeration system that uses the absorption of a refrigerant liquid by an absorber to remove heat from an environment. This type of system is usually used in applications where there is dissipated thermal energy to exploit and is mainly divided into four phases:

  1. The HOT SOURCE, which can be heat recovery from the cogenerator or thermal waste, is used to transfer heat to the “rich” solution of water and ammonia present inside the GENERATOR.
  2. The ammonia is then separated from the aqueous solution and the “poor” solution is returned to the absorber, while the gaseous ammonia is RECTIFIED to obtain maximum purity. The refrigerant is then cooled and liquefied in the CONDENSER.
  3. The liquid obtained is expanded in the EVAPORATOR, whereby changing its state, produces the desired refrigeration effect.
  4. From the EVAPORATOR, the ammonia, in the form of gas, is sent to the ABSORBER where the refrigerant is absorbed forming a solution rich in water and ammonia. This solution is pumped back into the GENERATOR to complete the cycle.

The heat from the absorber and condenser is then dissipated into the environment via an evaporative tower or a geothermal well.

The absorption refrigeration cycle is composed of seven main components: a generator, a rectification column, a condenser, an evaporative tower, an absorber, a lamination valve and a solution pump. The fluid involved in the process is ammonium hydrate (solution of water and ammonia).

The components of the absorption cycle.

Here is a more detailed description of the components of the ammonia absorber:

Generator: Start the cycle by evaporating ammonia from a concentrated aqueous solution. Evaporation requires heat input in the form of thermal energy provided by an external heat source

Rectification column: once the ammonia has been evaporated in the generator, the lean solution passes through a rectification column to purify the ammonia as much as possible which will then be used to produce the cold.

Condenser: The liquid containing ammonia passes through a heat exchanger where it releases the heat absorbed by the generator. This step causes the ammonia to condense, which returns to its liquid state.

Expansion valve: After passing through the condenser, the high-pressure ammonia is expanded through a controlled expansion (usually an expansion valve). This causes the pressure of the liquid to drop dramatically, causing the temperature to drop.

Absorber: This is the heart of the ammonia absorber. The ammonia vaporized in the evaporator mixes with an absorption solution called lean solution, which is generally water. The ammonia is then absorbed into the solution, releasing heat.

Evaporative tower: The heat generated by the absorption of ammonia by the water (exothermic process) generates heat that must be dissipated and this usually occurs through the use of an evaporative tower.

Solution pump (or liquid pump): After being absorbed, the solution containing ammonia (rich solution) is pumped to the generator. This pump requires energy to move the liquid.

Our idea of absorber: Enermatik

More than ten years ago, in fact, we designed our first ammonium hydrate absorber.

To date, Enermatik has become one of the most important and best-selling Zudek products in our “Refrigeration” line. But let’s see together what the advantages are arising from the use of this type of machinery.

Using an absorber brings various advantages, from an energy, environmental and economic point of view. Even more so an ammonia absorber, which therefore uses the most sustainable natural refrigerant currently on the market.

SUSTAINABILITY: ammonia, in fact, is the most sustainable natural refrigerant that exists. In fact, it is the only refrigerant liquid to have GWP (Global warming potential) and ODP (Ozone depletion potential) equal to zero.

ENERGY EFFICIENCY: the absorption system is certainly the most efficient system available as it is able to exploit the thermal energy dissipated by the system and transform it into electricity and/or cooling energy. Furthermore, in an absorption system we do not have the presence of compressors which are the source of greatest consumption when we talk about cold production.

OPERATIONAL FLEXIBILITY: Zudek ammonia absorbers are designed to suit a wide range of industrial applications, offering a solution tailored to your specific needs. Thanks to the flexibility and customization of our solutions we are able to respond to a very wide range of applications.


Ammonia absorbers represent a cutting-edge and sustainable choice for the world of refrigeration. We at Zudek are here to guide you and help you with the technological choice best suited to your needs, offering you solutions that increase efficiency and promote sustainability.

For further information or to receive personalized advice, do not hesitate to contact us at sales@zudek.com or at the link: CONTACTS

Zudek è un’azienda in continua evoluzione, specializzata nella progettazione e realizzazione di impianti all’avanguardia. Utilizzando la ricerca e l’innovazione, fornisce soluzioni ecologiche e ad alta efficienza energetica.

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