This year at the 6th IIR conference there was a new addition to the discussion, CO2. The use of CO2 in combination with ammonia, especially in industrial refrigeration – typically the main focus on the conference – and by itself, has become a more common occurrence in the intervening two years since the last conference. As such, this year’s conference was officially the ‘6th IIR Ammonia and CO2 Refrigeration Conference’.
Rise in use of CO2 requires specific tailored equipment
The emergence of CO2 discussion at the conference comes in line with the growing importance of R744 to the HVAC&R sector. However, with this growth also comes awareness of the idiosyncrasies that come with using R744. Heat Transfer Technologies presented a paper at Ohrid 2015 looking at the available products that tailor to R744’s demands to generate the highest level of system efficiency.
The presentation looked at several of these pieces of equipment: including heat exchangers based on round inner-grooved small-diameter copper tube and newly developed flat copper microchannel tubes, which can be applied in air conditioning and refrigeration equipment. And, it was the copper tubing that generated the biggest discussion point during the presentation.
Copper tubes hold the key to boosting efficiency and lowering costs
In Heat Transfer Technologies’ presentation, they mentioned the qualities of the aforementioned optimised copper tubing that make it suitable for use with CO2. This includes:
- Its small diameter tube
- Inner grooving patterns
- Thinner walls
- Smaller refrigerant charge
- Better for refrigerant mixing
The need for smaller tubing is linked to the fact that the volume of CO2 required to achieve the same cooling effect as fluorinated gases is much lower. This has made the use of CO2 an attractive property for smaller refrigeration applications such as vending machines.
In addition to this, using Microgroove’s copper tubing technology as an example, the presentation showed more practical advantages to using this form of equipment, too. These include cutting metal costs, improving energy efficiency, reducing heat exchanger weight while maintaining all the advantages of copper-,tube-based heat exchangers, but also reducing refrigerant charge by more than 50%. Later in the presentation, the positive properties of high-strength copper alloy were presented, including thin walls (as low as 0.25mm), and the ability to withstand twice the pressure of standard copper tubing.
6th IIR Conference
This was the 6th IIR conference, which occurs biannually in the south-western Macedonian city of Ohrid. The conference combines presentations from companies, academics and professors to create a unique sphere for new and old technologies to be assessed and bettered.