18 May 2017

O.3.1.3 Advanced round-tube, plate-fin (RTPF) heat-exchanger coils contribute to the high efficiency of heat pumps

Smaller-diameter, inner-grooved copper tubes can be found in a myriad of heat-pump products. Commonly referred to as “MicroGroove coils,” these advanced heat-exchangers are well suited for use in heat pumps. They are more efficient and more compact and contain a smaller volume of refrigerant compared to earlier generations of coil designs. MicroGroove coils are suitable for refrigerant-to-air heat exchangers, including evaporators and condensers as well as gas coolers. This paper will present examples of how these coils are used in diverse products such as clothes-drying heat pumps and heat pumps for residential heating and cooling. Once the smaller-diameter copper tubes are interlaced with aluminum fin plates and mechanically expanded, the ruggedness of the resulting round tube plate fin (RTPF) heat exchangers is remarkable. Manufacturing equipment and techniques that allow OEMs to produce these coils in volume will be described as well as sophisticated simulation software for optimizing tube circuitry and fin designs for maximum efficiency. These various factors combined are contributing to an atmosphere of creativity and innovation, increasing the energy efficiency of heat pumps while reducing the use of high-GWP refrigerants.