JAPAN: Mitsubishi Electric has developed an aluminium vertical flat tube (VFT) heat exchanger design which it claims can provide a 40% increase in heat pump air conditioner performance.
The new VFT heat exchanger is said to combine small-diameter flat tubes, arranged vertically and very compactly, and a high-performance refrigerant distributor with a double-tube structure that evenly distributes refrigerant.
With around 20% smaller internal volume than conventional aluminium horizontal flat tube (HFT) heat exchangers, the new VFT heat exchanger allows for reduced refrigerant charges.
To reduce refrigerant charge and also improve heat exchanger performance, Mitsubishi Electric focused on reducing the internal volume of the heat exchanger and increasing the surface area of air in contact with the refrigerant, in part by compactly arranging a large number of small-diameter flat tubes.
Conventional HFT heat exchangers also use a large number of flat tubes, but Mitsubishi Electric maintains that the design suffers from low heat exchanger performance because it does not evenly distribute the refrigerant.
Mitsubishi Electric says it also used proprietary analysis technology to develop a new fin design that significantly improves drainage, eliminating the problem of melted frost water freezing on the fins and reducing air contact with the heat exchanger, which reduces performance.
Mitsubishi Electric became the first air conditioning manufacturer to adopt aluminium heat exchangers in 2014 when the company included it in its City Multi VRF air conditioners.