MITSUBISHI ELECTRIC CORPORATIONPUBLIC RELATIONS DIVISION

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Mitsubishi Electric’s Aluminum Vertical Flat Tube Design Improves
Heat Exchanger Performance by an Unprecedented 40%
Lower energy consumption and less refrigerant will realize more efficient air conditioners

Fig. 1 Aluminum vertical flat tube heat exchanger

TOKYO, November 1, 2023 - Mitsubishi Electric Corporation (TOKYO: 6503) announced today that it hasdeveloped an aluminum vertical flat tube (VFT) design that improves heat exchanger performance by up to anunprecedented* about 40% in heat-pump** air conditioners used for heating and cooling (Fig. 1).
The new VFT heat exchanger combines small-diameter flat tubes, arranged vertically and very compactly, anda high-performance refrigerant distributor with a double-tube structure that evenly distributes refrigerant.
Compared to conventional aluminum horizontal flat tube (HFT) heat exchangers, Mitsubishi Electric’s new
VFT heat exchanger also reduces refrigerant charge thanks to about up to 20% smaller internal volume
compared to HFT designs. In addition, Mitsubishi Electric used proprietary analysis technology to develop a
new fin design that significantly improves drainage, eliminating the problem of melted frost water freezing on* According to Mitsubishi Electric review of stationary air conditioners for cooling and heating, as of November 1, 2023** Heats, cools, or warms water with high efficiency by transferring heat between outdoor and indoor air

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the fins and reducing air contact with the heat exchanger, which reduces performance.
While traditional heat-pump air conditioners use fluorocarbon refrigerants that contribute to global warming,reducing the refrigerant charge tends to lower heat exchanger performance. To reduce refrigerant charge andalso improve heat exchanger performance, Mitsubishi Electric focused on reducing the internal volume of theheat 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 the design suffers from low heat exchanger performance because it does not evenly
distribute the refrigerant, a mixture of gas and liquid under the influence of gravity.
Key Features
1) New design achieves unsurpassed heat transfer with less refrigerant
In conventional HFT heat exchangers, the refrigerant flows vertically inside the distributor and then into tubes
arranged horizontally, but the large number of tubes increases the difficulty of distributing the gas and liquid
refrigerant to all tubes evenly due to gravity’s influence. In the new VFT design, refrigerant flows horizontally
inside the distributor and then into the tubes arranged vertically, achieving uniform distribution unaffected bygravity (Fig. 2).
Also, using simulation technology and high-speed cameras to visualize the flow of gas and liquid refrigerant
inside the distributor, Mitsubishi Electric designed a new distributor with a double-tube structure that discharges
gas and liquid refrigerant through multiple small holes for even mixing (Fig. 3). The design incorporates theindustry’s smallest class diameter* flat aluminum tubes arranged highly compactly (more than 100 tubes perheat exchanger), which is about four times more tubes than in a conventional HFT heat exchanger.
As a result, heat exchanger performance is up to about 40% more efficient than that of a conventional HFT heatexchanger, and less refrigerant is required because the internal volume of the VFT heat exchanger is up to about
20% smaller.

Fig. 2 HFT and VFT heat exchangers

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Aluminumflat tubes
Double-tube
structure
Outer pipeInner pipe

Fig. 3 High-performance refrigerant distributors2) Newly designed fins efficiently drain water to maintain air conditioner efficiency
Heat-pump air conditioners use a defrost operation to melt frost on the outdoor unit during heating. However,
if melted frost water is not drained away, it can freeze on the fins and thus lower performance by reducing theamount of air coming in contact with the heat exchanger. Since the new VFT heat exchanger arranges the finshorizontally and therefore on top of each other, the fin design used in HFT units was not suitable, so Mitsubishi
Electric used proprietary drainage analysis technology to develop the industry’s first* high-drainage fins, which
combine drainage slits and a cut structure. (Fig. 4). Going forward, Mitsubishi Electric expects to develop heatpump air conditioners for heating and cooling that incorporate the company’s new VFT heat exchanger.

High drainage fins

Drainage slits
Cut structure

Fig. 4 High-drainage fins

Future Plans and Prospects
Going forward, Mitsubishi Electric will continue to refine its newly developed VFT heat exchanger, which itplans to combine with heat-pump air conditioners with the goal of contributing to a more carbon-neutral world.

“VFT” and “HFT” are pending trademarks of Mitsubishi Electric Corporation.
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###About Mitsubishi Electric Corporation
With more than 100 years of experience in providing reliable, high-quality products, Mitsubishi Electric
Corporation (TOKYO: 6503) is a recognized world leader in the manufacture, marketing and sales of electricaland electronic equipment used in information processing and communications, space development and satellite
communications, consumer electronics, industrial technology, energy, transportation and building equipment.
Mitsubishi Electric enriches society with technology in the spirit of its “Changes for the Better.” The company
recorded a revenue of 5,003.6 billion yen (U.S.$ 37.3 billion*) in the fiscal year ended March 31, 2023. For
more information, please visit www.MitsubishiElectric.com*U.S. dollar amounts are translated from yen at the rate of ¥134=U.S.$1, the approximate rate on the Tokyo
Foreign Exchange Market on March 31, 2023

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