Abstract: The present invention relates to a modular apparatus and methods for active heat exchange involving continuous atomization of chilled or heated fluid droplets, droplets projection, and formation of fluid film on a large surface for reciprocal two way heat transfer with circulating air. A closed, pleated, corrugated, thin-wall, heat conductive chamber (1) provides the large surface for formation of fluid film and separation between fluid and air offering short and rapid heat conductive path between fluid and air. An axial blower (11) integrated with the heat exchanger module provides re-circulation of air where the heat exchanger module (28) is situated. The modular heat exchanger (28) or multiple of which is integrated with other components such as a refrigeration unit (37), a heating element (25), and a central fluid reservoir (23) in which fluid is pre-chilled or preheated in the application of air conditioning and heating.