The U.S.-based International Copper Association (ICA) has rejoined  R744.com as a bronze partner to promote small-diameter MicroGroove tubes for heat exchangers.

ICA’s MicroGroove partnership in R744.com began in 2011.

MicroGroove smaller-diameter (such as 5mm/0.2in) copper tubes are used to create heat exchanger coils with high heat transfer coefficients. They are suitable for use in commercial and residential air conditioning and refrigeration products and can handle pressures up to 120Bar (1,740.45psi) in CO2 gas coolers.

“The International Copper Association collaborates with designers in the development of efficient heat-exchangers for ecofriendly products, including systems that use low-GWP refrigerants and natural refrigerants,” said Frank Gao, OEM Team Leader at ICA, who recently replaced Nigel Cotton as ICA’s Microgroove Program Manager.

“Our powerful HXSim simulation software, which is available for free to heat exchanger designers, includes R290 (propane) and R744 (CO2) as refrigerant choices for use with smaller diameter copper tubes,” Gao added. “Our strategy is to steer OEMs in the direction of ecofriendly, cost-effective product design.”

The copper MicroGroove tubes can withstand these high pressures without having to use a special copper alloy, or very thick tube walls. The tubes are ideal for CO2 applications, as the low viscosity of CO2 allows for smaller tubes with long circuits, resulting in optimal pressure drops. 

The technology is also space saving, as the smaller tubes reduce the internal volume and refrigerant charge, allowing for more compact coils in the heat exchanger.

PTAC studies

“New systems based on these designs may give owners and engineers the opportunity to reduce operational costs and energy consumption,” said the Copper Development Association, a member of the Copper Alliance, which is led by ICA, in a report published early 2020.

The report detailed the work of U.S. researchers, which ran simulations to identify optimal heat-exchanger designs in Packaged Terminal Air Conditioning (PTAC) systems and refrigeration systems.

The PTAC studies identified new condenser designs with smaller-diameter copper tubes that can reduce both energy consumption and operational costs for PTAC systems. The PTAC systems are widely used in hospitality and some commercial applications. 

The report also refers to a refrigeration study by U.S. OEM Sub-Zero detailing condenser designs that could reduce internal volume and total system charge while also maintaining or exceeding current performance levels.

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