BY MONIKA WITT

In Europe, the phase out of fluorinated gases with high global warming potential, known as F-gases in Europe and HFCs in the U.S., is resulting in severe shortages, causing prices to skyrocket and creating challenges for those that operate and maintain the systems.

The first HFC supply reduction of seven percent took place from 2016 to 2017, and demand is already exceeding supply. The European Union’s HFC phase-out regulations took effect in 2015, but there are still approximately 4,000 systems in use that rely on R404A, mainly because alternatives were not available.

Because of the tightened supply, prices had increased nearly every month during 2017, and by the end of the year were eight times higher than at the end of 2016.

From 2018 to 2020, the EU will cut the use of HFCs by 44 percent and then by 60 percent until 2022. After Jan. 1, 2018, large manufacturers, such as Chemours and Honeywell, no longer offered R404A, making R404A for maintenance even more difficult to get.

Part of the challenge has been that replacement refrigerants from the HFO series were not yet available, partially since public authorities would not approve storage vessels for these fluids. HFOs not only burn but create hazardous substances and require additional safety precautions that are not yet fully defined.

There are numerous HFC mixtures currently available, but all have a global warming potential that prohibits longterm use. The HFC mixtures currently offered for R404A have mostly a GWP above 1500 respective 1000, which means they need to be phased out after 2018 and 2024, respectively.

Old systems will have to rely on drop-in replacement refrigerants, but for a limited time. What’s more, most of the available HFC replacements are not suitable as drop-ins, which means they need system modifications.

In the long-term, older systems will need to be replaced and it is still open as to whether they will use HFOs or natural refrigerants, such as carbon dioxide or hydrocarbons such as propane. Going forward, it is likely that small systems will use hydrocarbons with limited charge, whereas larger commercial systems will head towards CO2 and, in some cases, indirect ammonia or ammonia-blend systems.

Another option, besides using ammonia for smaller application, is an ammonia-dimethylether blend, an azeotropic mixture that enables small capacities with air-cooled condensers even in warmer climates. In order to achieve wider acceptance, ammonia-dimethylether would require an ASHRAE classification.

Moving to natural refrigerants would create a long-term, sustainable solution with better efficiency.

THE F-GAS PHASE-OUT

The European Union is gradually reducing the permitted total quantity of F-gases, known in the U.S. as HFCs. The first F-gas regulation, which was designed to make systems leak-tight and spur more frequent checks, was adopted in 2006. That initial measure was replaced in 2014 by a new regulation, which took effect on Jan. 1, 2015.

Core elements of the actual F-gas regulation are:

• Phase-down: The supply of F-gases available on the market will be gradually reduced. The reference point consists of the average available quantity of F-gases available on the market from 2009 to 2012.
• Restrictions on use: F-gases that are particularly harmful to the climate will be gradually prohibited completely.
• Quota system: F-gas quotas will be allocated to the manufacturers and importers to control the actual consumption of F-gases.
• Leak tests: To avoid leakages, stricter regulations will apply in future to leak tests on refrigeration and air-conditioning systems.
• Extended operator obligations: Operators are responsible for ensuring that installation, maintenance, servicing, repairs or decommissioning is performed only by certified personnel. A

SUCCESSFUL AMMONIADIMETHYLETHER INSTALLATION

There is great potential for ammonia-dimethylether to serve as a replacement of F-gases, and WITT has had a successful installation of an ammonia-dimethylether refrigerant system in the old city of Cologne.

In the Cologne application, the challenge was not only to install the system without interrupting operation, but also to install the container in a very tight space on the roof top of an existing building. The goal was to reduce the refrigerant cost and cut the energy bill. At the same time the system needed to be maintenance-free.

WITT turned to a system that was charged with a blend of 60 percent ammonia and 40 percent dimethylether. Dimethylether had already been mixed into ammonia in former East-Germany to reduce the compressor end-temperature, particularly when using air-cooled condensers.

The azeotropic blend of 60 percent ammonia and 40 percent dimethylether was patented until 2016 and commonly sold under the name “R723.” However, the mixture was never classified by ASHRAE and as such has no safety-class assignment in either AHRAE or EN378.

For the risk analysis, the content of EN378 was adhered to and the highest safety standards of B3 refrigerants (compared to B2 for ammonia) were used for electrical equipment. In addition, the low charge of less than 0.25 kg per KW minimized the risk even in the unlikely event of a leakage.

The mixture of ammonia and dimethylether has similar properties of ammonia, including the same pungent typical smell to easily detect the smallest leakages, but with an approximate 10- to 20-degree lower compressor end temperature.

The customer has experienced notable savings, particularly because the cost of R134a and R404a, which the new system eliminated, have increased dramatically, if it would have even been possible to get it. Additionally, it has created a reliable operation and low electrical bill.