4.3 Improved Heat Exchanger Design

Heat exchanger design is a constantly evolving science with new ideas of how to maximize heat transfer. MicroGroove technology is one of the latest ways of enhancing efficiency.

MicroGroove technology involves the use of smallerdiameter, specially enhanced copper tubes in heat exchangers. New systems based on these designs may give owners and engineers the opportunity to reduce operational costs and energy consumption, according to the U.S.-based Copper Development Association (CDA) in a 2020 report.87

Smaller-diameter copper tubes have been used in hydrocarbon systems requiring a small charge. In a paper presented at the 2018 Purdue Conferences, optimized domestic refrigerator condenser coils using hydrocarbon refrigerants were shown to deliver needed cooling capacity while using smaller- diameter (5mm/0.2in) MicroGroove copper tubes that contain a small charge of refrigerant.88

Israeli heat-exchanger manufacturer Lordan Coils has developed a cold-climate R290 residential heat-pump water heater (HPWH), using 5mm MicroGroove copper tubes to achieve a low charge.89 The MicroGroove 5mm copper tubes are used to create bent L-shape heat exchanger coils with high heat-transfer coefficients, resulting in higher seasonal energy efficiency ratios (SEER). The small- diameter tubes mean less material is needed, giving lower system weight while maintaining the same capacity.

The International Copper Association (ICA) has released new design and simulation software for heat exchangers that use small-diameter MicroGroove tubes. The software – HXSim “Small Diameter Copper Tube Air Conditioning Heat Exchanger Simulation Tool” Version 3.0 – can be freely downloaded online.90

Cutting cost, charge

MicroGroove tubes could help reduce the cost of hydrocarbon-based self-contained display cases, improving efficiency and keeping charges to a minimum.