What is the primary function of a heat exchanger in thermal engineering?

A、Toconvertthermalenergyintomechanicalenergy.
B、Tofacilitatethetransferofheatbetweentwoormorefluidswithoutmixingthem.
C、Toincreasethetemperatureofasinglefluid.
D、Tostorethermalenergyforlateruse.