TEAP tech report highlights natrefs as alternatives under Kigali

At 39th Meeting of the Open-Ended Working Group (OEWG39) of the Parties to the Montreal Protocol in Bangkok, Thailand (11-14 July), the Replenishment Task Force of the Technology and Economic Assessment Panel (TEAP) – an advisory body to the Montreal Protocol Parties – presented a report highlighting natural refrigerant alternatives that are and will be used in the future.

The 2017 progress report takes a look at alternatives to HFCs for HVAC&R applications. Household refrigerators are particularly likely to use hydrocarbons, throughout the world.

“By 2020 around 75% of new refrigerators will likely contain [hydrocarbon, HC] R600a (a small proportion using HC-HFO blends), with the remainder containing HFC134a or HFO-1234yf,” the report says.

The use of the HFO will be limited “due to higher cost, and concerns on flammability,” it adds. 

Some difficult roads to go down

For fisheries, the move to low-GWP solutions is being addressed and there has been some shift towards ammonia and CO₂. 

“R717 is in use in fishing vessels, but the adoption of R744 systems and especially transcritical systems will require further development,” the TEAP report says.

However, when it comes to trucks and logistics providers, there is quite a lot of disagreement about what the solution should be. Some recommend flammable refrigerants, while others are looking at CO₂ or cryogenic freezing using nitrogen, the report explains.

Cars also seem to be a market full of different competition. “For cars, R744 is also an alternative (as well as HFOs), which some premium models have started using in 2017. R744 is also under evaluation for use in heat pumps on electrified vehicles,” the report says.

Other product markets such as air conditioners and heat pumps will likely see competition between natural refrigerants CO₂ or HCs, HFC R32, and HFOs. Many manufacturers look set to go down the natural refrigerant path.  “In India, there is widespread commercialisation of production of HC R290 split air conditioners, with production line conversions underway in several other high ambient temperature countries,” it says.

Hope lies with CO₂ innovation

The report also takes a look at the commercial refrigeration sector, highlighting growing use of CO₂ in cascade and transcritical systems in the supermarket sector.

“Transcritical systems are undergoing extensive component and system R&D on ejectors, adiabatic condensing, sub-cooling and parallel compression to reduce their energy consumption at higher ambient conditions,” the Montreal Protocol advisory body’s report states.

They place particular emphasis on smaller applications. “Walk-in applications with condensing units are increasingly using R744,” the report says.

“Self-contained systems are moving from R404A and HCFC R22, to HC R290 or R744,” it says.

However, TEAP warns that safety standards remain a barrier for larger equipment using propane as the refrigerant.

Low-charge ammonia – a way forward?  

The need to embrace low-charge ammonia solutions in Industrial refrigeration, the report says, is of particular importance to achieve the HFC phase-down.

“Market reports indicate a move from NH₃ to HFCs in some countries after accidents due to neglected rules and standards,” it says.

TEAP adds that increased training and lower charge could increase uptake.

The report adds: “Low charge is not clearly defined and is used in different contexts, creating confusion about the terminology.”

As previously reported on ammonia21.com, there have been moves to remedy this situation. 

Recently Professor Pega Hrnjak from the University of Illinois at Urbana-Champaign, an expert on ammonia refrigeration systems, offered three categories for low-charge ammonia in the absence of an industry consensus, namely:

• Ultra-low charge: Up to 2.5kg charge
• Very low charge: Up to 50kg charge
• Low charge: Up to 100kg charge

The TEAP report also identifies energy performance and operation in high ambient temperature conditions as particular concerns to address.