Plate heat exchangers consist of metal plate pairs arranged to provide separate flow paths for two fluids. Heat transfer occurs across the plate walls. Plate heat exchangers typically have U-factors three to five times higher than shell-and-tube heat exchangers. The high turbulence created by the corrugated plate design increases convention and increase U-factor.
Usually plate heat exchangers have a larger pressure drop than shell-and-tube heat exchangers. Plate heat exchangers takes less space than shell-and-tube for some capacities. Plate heat exchangers for HVAC are not designed to use steam.
Plate heat exchangers are designed for high static pressure and are used for the heating and cooling systems (buildings with high static pressure). Boilers are usually designed for maximum of 150 psi working pressure, and chillers are designed for maximum of 300 psi working pressure; and cannot be used for high static pressure applications. Plate heat exchangers in HVAC systems are more common than shell and tube heat exchangers. In heat exchangers, the primary hot water temperature should be designed for 10℉ higher than secondary hot water for heating systems and the primary chilled water should be designed for 5℉ lower than the secondary chilled water for cooling systems.
