What are the main types of compact heat exchangers and their applications?

Types include: Plate-and-frame (gasketed, easy maintenance, food/pharmaceutical/HVAC), Brazed plate (no gaskets, higher pressure to 30 bar, refrigeration), Welded plate (high pressure/temperature, aggressive chemicals), Plate-fin (very high surface area/volume, cryogenic/aerospace), Printed circuit (diffusion-bonded, extreme conditions, offshore), and Spiral (self-cleaning, handles solids, sewage/slurries). Selection based on pressure, temperature, fouling tendency, cleaning needs, and material compatibility. Compact exchangers offer 2-5x higher surface area per volume than shell-and-tube.