HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA COME INTO DIRECT CONTACT WITHOUT CHEMICAL INTERACTION (safety devices in general F16P; fluid heaters having heat generating means F24H; with an intermediate heat-transfer medium coming into direct contact with heat-exchange media F28D15/00 - F28D19/00; details of heat-exchange apparatus of general application F28F)

Description

F28C covers heat exchangers where thermal energy transfers directly between two fluids or media in contact without intermediate barriers or chemical reactions occurring. This subclass includes contact condensers, cooling towers, spray-type exchangers, and direct-contact gas-liquid or liquid-liquid systems where mixing or intimate contact facilitates heat transfer. Devices classified here typically rely on physical heat exchange mechanisms such as evaporative cooling, direct immersion, or fluid spraying rather than separated surface heat transfer covered by other F28 subclasses.

Filing statistics

CPC subclass F28C recorded 6,355 patent applications worldwide between 2013 and 2023. Annual filings grew from 318 in 2013 to 628 in 2023 (+97%), peaking at 770 applications in 2020. The most active applicants in class F28 are VALEO SYSTEMES THERMIQUES (1,945 applications), MITSUBISHI ELECTRIC CORPORATION (1,518 applications) and MAHLE INTERNATIONAL (1,120 applications).

Source: EPO PATSTAT, worldwide filings