The ammonia evaporator is a heat exchanger designed to work in the cold section of an ammonia-based refrigeration system. Ammonia (NH3), also known as R-717, is the preferred natural refrigerant for industrial refrigeration of meat, wine, dairy, beer, food, etc.

At the outlet of the expansion valve, the ammonia comes out cold both in the liquid phase and in the gas phase. Therefore, the cold ammonia must pass into a separator container, where the liquid will settle in the lower part and the gas will remain in the upper part. Next, a pump drives the liquid ammonia through the ammonia evaporator, to cool the space to be refrigerated.

From what has been said before, an ammonia evaporator is an industrial evaporator fed by a cold refrigerant in a liquid state. This makes it work differently from a direct expansion evaporator, which is a refrigeration unit that works with gaseous refrigerant. However, both evaporators are physically very similar, both allowing efficient conductive and convective heat transfer.

How is an ammonia evaporator made?

The ammonia evaporator can be designed for the direct transfer of cold to the space to be cooled. In this case, cold ammonia from the refrigeration system is pumped directly into the evaporator coil tubes. A fan then forces air through the evaporator tube fins to cool the space to be cooled.

On the other hand, an industrial ammonia evaporator, designed for indirect cooling, is more complex, since it performs two-stage cooling. That is to say, in a first evaporator or heat exchanger of the shell and tube type, the ammonia cools a solution of water with glycol. Then, said cold water is pumped to a second evaporator, which is inside the space to be cooled. This last evaporator has the same design and operation as the aforementioned direct transfer evaporator.

Because ammonia strongly corrodes both copper and aluminum, all refrigeration unit piping is stainless steel. This is one of the main differences between an ammonia evaporator in relation to another evaporator designed for another type of refrigerant.

Importance of industrial refrigeration with ammonia evaporator

Ferdinand Carré built and patented the first machine to produce ice, using ammonia, in France, in mid-1859. Then, in 1876, the German Carl Von Linde manufactured the first refrigeration unit by mechanical compression of ammonia. Therefore, the use of ammonia in industrial refrigeration is nothing new.

In the mid-1940s, the first synthetic refrigerants based on HFC (hydrofluorocarbon) and CFC (chlorofluorocarbon) compounds were produced. These limited the use of natural refrigerants (ammonia and carbon dioxide) since they simplified the construction of refrigeration systems. However, when it was discovered that these gases destroy the ozone layer and cause global warming, their use was restricted.

From what was said above, natural refrigerants such as ammonia and carbon dioxide have regained great importance in the world. This is because they are not harmful compounds to the environment and because they are the alternative to replace synthetic refrigerants. Consequently, the use of ammonia refrigeration units will be more and more frequent, in industrial and commercial applications.

Maintenance of ammonia refrigeration equipment

Both the industrial ammonia evaporator and the compressor, pipes, condenser, pumps, etc., need periodic inspection and strict preventive maintenance. In this way, the risk of ammonia leaks can be reduced and the risks to people’s health can be reduced. Good maintenance is the main safety measure.

Ammonia detection devices

It is essential that the compressor room, ammonia evaporator, ammonia condenser, pumps, etc., have ammonia detectors. These teams must activate an alert for the operations personnel so that they can take the pertinent measures in time. Currently, there are very accurate and portable detectors.

Implementation of the indirect cooling industrial evaporator

This measure is very important to avoid as much a possible risk to people or possible contamination of food, drinks, meat, etc. With indirect cooling, only water with glycol is used to bring cold to a second evaporator. This second evaporator can go inside the Air Handling Unit of the air conditioning system of the building, hospital, shopping center, etc. In the same way, to protect the food, the second evaporator is placed inside each cold room.

Do you need an evaporator for your ammonia air conditioning or refrigeration system?

If you are looking for an ammonia evaporator to the exact measure of your needs, at Intersam we design and manufacture it for you, complying with all regulations. We are a company with many years of experience in the design and construction of industrial evaporators and condensers. Therefore, we can guarantee you a device that is truly adapted to your air conditioning system, and with a long useful life. The coils of our ammonia evaporators are manufactured with AISI-316 stainless steel and TIG welding. Finally, the coil and the fans are supported by a solid aluminum structure.

You can obtain more information about our industrial ammonia evaporators by visiting our catalog.