Steam-to-water, hot water and glycol loops, thermal fluid, tank and suction heating, and product heating. Steam duty is where the U-bend earns its keep, because the differential temperature is large by definition.
Process cooling on tower, chilled or glycol water, and gas cooling where the low gas-side coefficient and the pressure drop budget fight each other.
Vapor condensing, reflux and column overhead duty, and condensate and feedwater heating. Where noncondensable gas and condensate drainage decide performance more than surface area does.
CIP solution heating, pasteurization and HTST, culinary and clean steam, and sanitary product cooling. Duty that has to hit a thermal target and survive an audit at the same time.