Over the past several months, the Epsilon team has engaged on a number of Central Utility Plant (CUP) projects that include the validation of ammonia as a refrigerant versus more traditional CFC/HCFC-based refrigerants.
Traditionally, ammonia is used as a refrigerant in industrial applications such as food processing and cold storage. It is far less common in HVAC applications, where synthetic refrigerants – those based on CFCs and HCFCs – have dominated the market. But while our industrial clients often ask us to look at ammonia, we’ve also seen increasing requests from non-industrial clients with aggressive sustainability goals, given the very low Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) ratings.
Here’s a high-level overview of key considerations for ammonia as a refrigerant for your next CUP project:
Cost
A typical chiller using ammonia costs twice as much as an equivalent centrifugal chiller utilizing synthetic (CFC/HCFC-based) refrigerants. This can easily add 30 to 50 percent to the cost of the CUP as a whole.
Size
A typical chiller using ammonia is comparable in physical size to an equivalent centrifugal chiller utilizing synthetic refrigerants. However, the design of an ammonia-based CUP must accommodate additional ventilation to meet engine room codes. This adds extra complexity and space requirements to the CUP.
Schedule
Selecting chillers that use ammonia can easily add months to an overall CUP build schedule. The manufacturing lead-time for ammonia-based chillers is currently an order of magnitude longer than more traditional, synthetic-refrigerant chillers.
Efficiency
Chillers utilizing ammonia may provide better energy efficiency than comparable centrifugal chillers using synthetic refrigerants. However, the actual impact on CUP efficiency is highly dependent on the operating temperatures (both chilled-water and condenser-water), meaning that CUP design must be first optimized for system needs and then evaluated for chiller efficiency impacts.
Safety
Ammonia is toxic, flammable, and corrosive, so careful consideration must be given to the potential impacts on operating personnel and the materials used in the systems.
Sustainability
Ammonia has far better ODP and GWP ratings than traditional synthetic refrigerants, which can be meaningful depending on the importance of sustainability metrics to the client and application.
What does all this mean for project owners and stakeholders considering ammonia as a refrigerant? Every project, client, and circumstance is different and should be evaluated on the metrics specific to that case. If you’re considering a new or replacement CUP and want to better understand the relative merits of ammonia as a refrigerant, reach out to Epsilon for a comprehensive analysis of your project.
