Unlike traditional heat exchangers, the brazed plate heat exchanger consists solely of surfaces that make an active contribution to heat transfer.     Brazed plate heat exchangers are widely used in refrigeration plants. They are normally used to transfer heat from the refrigerant – the primary fluid – and from water or brine as the secondary fluid. Units in the Alfa Laval AC series of copper-brazed heat exchangers are mainly used as : - Evaporators for dry expansion and cooling water - Condensers for rejecting or recovering heat to water - De-superheaters for partial heat recovery to water - Economizers for cooling liquid refrigerant and super-heating vapour refrigerant. They can also be used as : - Sub-coolers to cool liquid refrigerants using well water - Intermediate heat exchangers in the absorption cycle, to preheat the diluted solution or to pre-cool the concentrated solution.