Ammonia: A cool choice for energy efficiency

Ammonia refrigerant has been used since the 1850s in a variety of applications. It is an affordable refrigerant  for reducing the use of GWP refrigerants and meeting international standards. Anil D. Gulanikar, Refrigeration Consultant and Past President of the Association of Ammonia Refrigeration, sheds light on how the practical use of it with regulations and proper design can also reduce the risks associated with the use.

We have to use refrigerant when building an industrial refrigeration unit. Refrigerated systems for food processing, beverage processing, meat processing, and any other kind of cold storage application for food are included in the industrial systems. So, what goes into the decision-making process for the selection of refrigerant?

The refrigerant should be reasonably priced, easily accessible, user-friendly, and energy-efficient. These are the fundamental specifications for industrial applications’ use of refrigerants. With the changing dynamics of the world driving towards curbing carbon release, natural refrigerants have gained momentum. Ammonia is an ideal solution for the refrigerant issue in all these clamors. In India, the cost per kilogram is between 100 and 110 rupees. This is the most affordable refrigerant currently on the market. As it is made in India as a byproduct of the fertilizer industry, the price fluctuation will not leave holes in our pockets. As long as the fertilizer industry remains in India, this refrigerant will be accessible, and imports are not anticipated. 

Insights on Ammonia

Ammonia needs to match the 99.5 percent purity, and in India, we can get it as pure as we want if we insist on it. ASHRAE has categorized it in the B2L category. Ammonia is not flammable; it only catch fire above temperatures of 750–650 degrees Celsius. ASHRAE describes it as having a lower flammability, allowing us to use this refrigerant safely in any refrigeration system.

Ammonia’s basic formula is NH3, a very robust compound refrigerant that does not break; other refrigerants are mixtures / blends. That vary based on the circumstances, the properties of ammonia stay unaltered even after being used repeatedly at different temperatures. Next, there are two criteria: the global warming potential (GWP) and the ozone depletion potential. Ammonia has less  than one potential for global warming, although the focus is currently on that possibility. While HFCs and HCFCs provide a range of substitutes, unlike ammonia, they become more explosive as their GWP drops. Ammonia  have zero ozone depletion potential, while ammonia has a global warming potential of less than 1 , making it a classified substance. 

Precautions

At 30 parts per million for eight hours, ammonia exposure limits are safe for workers to work until retirement. The consumer is responsible for any leaks, and the amount can vary between 25 and 30 parts per million. Many people have misconceptions about ammonia .  Gas cylinder or any other potentially explosive gas we are using in our house.   Disposing of these myths and ensuring ammonia is handled responsibly in the marketplace is imperative.

There have been many reports of gas cylinder explosions, but these incidents will persist if we don’t take safety measures to safeguard everyone. The highly flammable nature of gasoline has resulted in numerous hazardous outcomes using gasoline-powered vehicles. Should we, therefore, discourage using it? Not at all! We are keeping up with it because it benefits us.

The mishaps involving ammonia refrigerant can be avoided if the system is properly designed by an engineer who adheres to standards. We must follow  all standards and procedures during a system’s design or conceptualization phase itself . In that case, the duration of the life of the ammonia refrigeration system plant on a global scale will be  more than  20 years . The ammonia refrigeration system life is normally considered is 15-year lifespan.

I have worked in this field for over 38 years, designing and running systems that have never resulted in an accident. Failure to perform routine maintenance causes malfunctions and mishaps. Although the causes vary, more deadly accidents have resulted from refrigerant leakage, either CFC or HCFC. We cannot smell it, and normally there are no sensors installed . While in ammonia, it is normal practice to install sensors . We will be able to detect a leak if we exercise caution. There are pros and cons to using ammonia, but we need to go beyond the floating myths related to this refrigerant.

Serious problems are at bay until ammonia concentrations surpass 1000 parts per million. Nonetheless, safeguards are in place, and concentrations between 100 and 200 ppm do not create any issues. The energy efficiency is highest than all other refrigerant and  it has the highest COP. Because of its high heat conductivity, low viscosity, high latent heat , low specific volume, and low viscosity, ammonia is the most energy-efficient refrigerant, outperforming any other refrigerant. The excellent energy efficiency of ammonia can be attributed to these specific features.

Case Study

The project comparison between R134A and ammonia consistently shows a higher COP with the latter,  In air-cooled applications, ammonia demonstrates a significant 60 per cent reduction in power usage and a 37.6 per cent in medium temperature application as compare with  Freon. These findings are derived from factual information from one site . Notably, ammonia refrigeration is increasingly prevalent in public facilities like airports, with ongoing research supporting its broader application. A case study involving minus 25 degrees Celsius storage highlights ammonia’s superior energy efficiency compared to CO2. In regions like India, where ambient temperatures are high and the cost of CO2 systems prohibitive; ammonia is considered the most natural and energy-efficient and cost effective refrigerant.

Standards

The Association of Ammonia Refrigeration developed a standard for ammonia refrigeration system design and installation practices. After being given to the environmental ministry, the suggested standard was sent to the Bureau of Indian Standards and eventually published as an Indian standard as IS17773-2-22. Adhering to these guidelines can demonstrate ammonia’s energy efficiency, sustainability, and environmental friendliness, as well as its low accident intensity that poses no risk to users.