In fin tube heat exchangers, the fluid (gas/water/glycol/refrigerant/etc.) circulating through the coil’s tubes is extremely important for the coil’s overall performance – it’s half the battle, along with airside heat transfer. The degree to which the fluid contacts the tube walls affects the coil’s performance and influences a system's overall efficiency – the more the fluid comes into contact with the tube wall, the better – and more economical – the heat transfer.

Around 2010, the first refrigeration systems operating on transcritical (TC) CO2 (R744) – commonly called booster systems – began cropping up in North American supermarkets. Since then, usage of TC CO2 systems has grown steadily and they’ve become viable options for places like supermarkets, food warehouses, and ice rinks, as more organizations move away from traditional HFC refrigerants. Natural refrigerant market accelerator Shecco estimates that TC CO2 systems grew from 140 in 2008 (all in Europe) to more than 35,000 systems worldwide today.

There are dozens of commercially available refrigerant options on the market today, including numerous refrigerant blends, which aim to replicate the effectiveness of former workhorses like R22, the production of which was made illegal as of January of this year. Two popular examples of refrigerants developed in the last 30 years or so that are used in the HVAC industry are R-410A and R-407C. These two refrigerants are often used for similar applications, but they have some marked differences that should be understood and considered when deciding between them.

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For commercial operations that rely on effective heat transfer, external corrosion of heat exchanger components is a major concern. When left unchecked, corrosion can significantly reduce a coil's effectiveness, but sometimes it’s difficult to know which anti-corrosion option best meets your needs.