New Heat Exchanger Introduced

TOKYO, JAPAN (Feb. 22, 2006) - DENSO Corp. announced it has developed a unique double-pipe internal heat exchanger for a car's air conditioning (A/C) system that increases cooling performance by up to 12 percent ...

Jan. 1, 2020

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NEW TECHNOLOGYNew Heat Exchanger Introduced
For A/C Systems TOKYO, JAPAN (Feb. 22, 2006) - DENSO Corp. announced it has developed a unique double-pipe internal heat exchanger for a car's air conditioning (A/C) system that increases cooling performance by up to 12 percent.

AC System Schematic
(Illustration: DENSO) The company says this is the first-ever double-pipe internal heat exchanger developed for a front A/C system that needs to be installed in a limited space. The A/C system was introduced this year in North America on the Lexus GX470 and elsewhere in the world on the Toyota Prado. The double-pipe internal heat exchanger integrates two pipes, which are separated in a conventional refrigeration cycle, into one pipe with inner and outer tubes. In the refrigeration cycle, the low-temperature gaseous refrigerant flows in the inner tube and exchanges heat with the high-temperature liquid refrigerant flowing in the gap between the inner and outer tubes.

Notice the spiral grooves that face the outer tube's walls. These are designed to enhanced the system's heat exchange properties.
(Illustration: DENSO)The inner tube wall has spiral grooves that face the outer tube, enhancing heat exchange. This allows the internal heat exchanger to achieve a higher cooling performance within a shorter pipe length, says DENSO. Specifically, with this unique structure that employs more surface area in the heat exchange process, the system can increase cooling performance by 5 percent to 12 percent at the same power level, within a total length of just under 16 inches, adds the company.

Double-pipe Internal Heat Exchanger
(Illustration: DENSO)

When the air conditioning system is installed in the engine compartment, pipes need to be flexible so they can be bent to fit with the other systems and components. However, in the double-pipe internal heat exchanger, the gap between the inner and outer tubes is likely to be crushed during the bending process, making it unable to function as a refrigerant path. DENSO says it solved this problem by creating the spiral grooves on the inner tube wall. As a result, the tubes are not crushed when bent and A/C systems using this heat exchanger can be installed in the same space as a conventional front air conditioning system.

"DENSO has been dedicated to 'mono-zukuri,' or the art of making things since we opened our doors more than 50 years ago," said Hikaru Sugi, DENSO's managing officer in charge of the Thermal Systems Business Group. "That focus helped us develop the spiral grooves on the inner tube wall of the double-pipe internal heat exchanger."

(Source: DENSO)