Selecting a refrigerant should not be about flammability or toxicity, these are issues that can be addressed by engineering solutions.
The primary factor that should determine refrigerant selection is energy efficiency, according to Selwyn Wallace, managing director of Engas Pty Ltd.
“It is an important decision because a wise choice can save you or your customers a lot of money,” he said.
Wallace said refrigeration and air conditioning systems have improved in efficiency over the years with the introduction of advanced controls, ductless systems, variable refrigerant flow and energy management tools.
“Tie these components together to optimise energy use and the results are impressive. However, blended hydrocarbon refrigerants can deliver energy savings far in excess of any of these technologies as long as they are applied correctly," he said.
Recognising that Australia has one of the hottest climates in the world, Wallace said its important to ask about critical temperature when selecting a refrigerant.
He said conventional refrigeration cycles can only operate efficiently using fluids well below critical temperature.
For example, R22 has a critical temperature of 96 degrees Celsius while R410 and R32 have a critical temperature of 71 degrees Celsius.
“This is why R410a and R32 will not work efficiently in very hot climates such as Australia and the Middle East because the temperatures in those places can rise to over 48 degrees Celsius,” Wallace said.
“In fact it can rise to 70 degrees Celsius for equipment in the direct sun on the roof. Most blended hydrocarbon refrigerants have critical temperatures in excess of 90 degrees Celsius.
“The critical temperature of the refrigerant should be as high as possible above the condensing temperature in order to have a greater heat transfer at a constant temperature.”
Wallace said companies that fail to embrace energy efficient technologies will be left behind. In addition to high critical temperatures, Wallace said hydrocarbon refrigerants reject heat 50 per cent faster than chemical refrigerants.
He said the HVACR industry has a lot to learn from the aviation industry.
“As the world's largest passenger airliner the Airbus A380 was an amazing technological feat but Airbus recently announced plans to cease production in 2022, why?” he asked.
“It's because the A380 wasn't fuel efficient. It's proof that energy efficiency is critical.
“If it can happen in aviation, it can happen in HVACR.”
Wallace said the application of highly efficient but flammable hydrocarbon refrigerants can be done safely.
“There is no reason to choose extremely harmful and inefficient fluorocarbon refrigerants when solutions are readily available using natural refrigerants for the majority of applications,” he said.
A recent development that is set to have a significant impact on hydrocarbon use is the introduction of higher charge limits by the International Electrotechnical Commission (IEC).
The IEC has increased the allowable charge limit on hydrocarbon refrigerant applications to 500g under the IEC 60335-2-89 global standard.
It is a significant increase on the previous maximum approved amount of 150g.
This is an amendment that has been in development since 2014 and the introduction of these long-awaited changes will see A3 refrigerant charge sizes increase to 500g and A2L refrigerants to 1.2kg.
Initially the IEC voted against the amendment, which was lost by one vote. However, a recount was called after Malaysia’s “no” vote was rejected due to a technicality.
Under procedural rules votes must be supported by a technical justification which wasn't provided by Malaysia.
While there has not been an official announcement, the matter will be discussed at an IEC standards meeting on June 17, 2019.