Ammonia Absorption System

According to Science Direct, ammonia absorption refrigeration systems are “a well-known alternative to vapor-compression systems to achieve a cold space, especially where electricity prices are high.” 

These refrigeration systems may take up more space compared to more traditional alternatives, but they can be located outside of a building or structure and can be designed vertically to take up as little space as possible. What’s more, they don’t have a noisy compressor, which makes them quieter than other refrigeration systems. 

But many don’t know about how ammonia—a naturally-occurring substance with a very low boiling point—is used for its cooling properties, including in food processing and preservation, as an industrial refrigerant, and even in some air conditioning applications.  

Anhydrous ammonia and water come together to create a refrigerating effect. Here’s how the system works. 

How Does the Ammonia Absorption Cooling Cycle Work? 

An ammonia absorption refrigeration system uses industrial ammonia for cooling because it has a very low boiling point of -28° Fahrenheit. Typically, an absorption cooling system relies on two fluids, like ammonia and water to absorb the coolant, which provides the desired cooling effect.

The absorption cooling cycle has three phases: 

1. Evaporation: Ammonia, a liquid refrigerant, evaporates at a low temperature in a partial pressure environment. This extracts heat from its surroundings, including the compartment around it. 
2. Absorption: The second fluid draws out the depleted ammonia in its gaseous state, which creates a refrigerant-saturated liquid for cooling. This liquid subsequently flows to the next step. 
3. Regeneration: To complete the cycle and begin again, the refrigerant-saturated, ammonia-based liquid is heated, which causes the refrigerant to evaporate out once more.
    

In many instances, evaporation happens at the bottom end of a narrow tube. Bubbles of refrigerant gas force the refrigerant-depleted liquid to a higher chamber, which allows the refrigerant liquid to flow into the absorption chamber due to gravity. 

Once heated, the gaseous refrigerant must pass through a heat exchanger, sending heat outside the system. It’s why many refrigeration systems expel hot air. After expelling the head, the liquid condenses and flows to begin the evaporation phase again. 

Through this process, ammonia is used to create the mechanical circulation of cooled liquid for refrigeration, all without the use of a compressor pump that requires electricity and has the potential to fail. 

A (Brief) History of the Ammonia Absorption System 

In the late 1800s, any existing refrigeration systems used the absorption principle. It didn’t use electrical energy and the main energy source, needed to heat the ammonia, came from something like a steam boiler or a burner.  

However, in the 1950s, low energy prices and emerging energy-based compressors took the place of ammonia absorption refrigeration systems. For quite some time, these cooling systems were only used in specific applications and industries, typically where users needed a highly-reliable solution that could create very low temperatures.  

So, why are ammonia absorption systems used more widely today? It has to do with low energy consumption. These ammonia absorption cooling systems run on residual heat, which limits the total energy consumption level needed for refrigeration. 

Today, thermodynamic ammonia absorption-based systems are often used in tandem with more modern refrigeration control techniques. This increases the efficiency of the system while still protecting the environment and saving energy. 

How Does It Compare? 

An ammonia absorption refrigeration system is an appealing alternative to more conventional refrigeration systems. Traditionally, we think of refrigeration as cooling a substance, a space, or a system, but the actual process of refrigeration is all about removing heat to create the desired cooling effect. 

Refrigeration systems extract heat, bringing refrigerant substances (like ammonia) to cooler temperatures and expelling the heat to the ambient area around it. Traditional refrigeration systems, like an ammonia absorption system, require the use of a refrigerant that evaporates at low temperatures. These systems then increase the pressure to condensate the refrigerant again in a repeated cycle.  

However, unlike the ammonia absorption refrigeration system that uses only industrial ammonia, water, pressure, and heat, conventional systems are mechanically-driven and require the use of a compressor that’s powered by electricity.  

In an ammonia absorption refrigeration system, this electricity-powered compressor is traded out for a circuit that allows the liquid to flow freely. By exposing water and ammonia to a heat source, thermal energy, not electricity, is used to create a cooling effect. 

So, besides not needing as much energy to power it, what additional benefits are there to choosing an ammonia absorption system? 

• Wasted heat or heat that is a by-product of other processes can be used to cool your systems. 
• Ammonia has a low boiling point, which means that it can be used to cool a refrigeration system to subzero temperatures. 
• Because it doesn’t rely on mechanical compression, an ammonia absorption system is more reliable—and quieter—than other refrigeration solutions. 
• Ammonia is a naturally-occurring refrigerant that does not contribute to greenhouse gasses or harm the ozone layer. 
• Ammonia has a very strong smell that makes it impossible to be around. It also creates a burning sensation in the air. This means that even the slightest leak is easy to detect, making it much safer to use compared to other refrigerants. 

Airgas Specialty Products: Your Supplier of Industrial Ammonia 

At Airgas Specialty Products, we are the leading supplier of anhydrous and aqueous ammonia across the continent, with a reputation for reliable service anytime, anywhere. This includes providing industrial ammonia for use in a range of applications including: 

• Water purification 
• Manufacturing plastics and textiles 
• As one of the most common agricultural fertilizers (thanks to its high Nitrogen content) 
• In the creation of explosives, chemicals, dyes, and even pharmaceuticals
   

Additionally, Airgas Specialty Products provides industrial ammonia for refrigeration systems, as well as safety and risk management training programs, inspection, sales, rental, and design of storage containers, system maintenance and repair, researched answers to technical questions, system engineering, emergency response services, and more. To learn how we can fulfill your industrial ammonia, engineering, and safety requirement needs, connect with our team of experts today.