A heat exchanger and a condenser are both devices used to transfer heat from one fluid to another, but they have different applications and designs.
Purpose: A heat exchanger is used to transfer heat between two fluids without allowing them to mix. A condenser is used to condense a vapor into a liquid.
Design: Heat exchangers typically have multiple tubes that the fluids flow through, separated by a barrier to prevent mixing. Condensers have a larger surface area and are designed to promote the transfer of heat from the vapor to the surrounding cooling fluid.
Operating conditions: Heat exchangers are used under a wide range of temperatures and pressures, but condensers are typically used in high-pressure applications to condense steam or other high-pressure gases.
Fluid flow: In a heat exchanger, the fluid flow is usually counter-current or parallel, while in a condenser, the fluid flow is usually counter-current.
In summary, heat exchangers are used to transfer heat between two fluids while maintaining their separation, while condensers are used to condense a vapor into a liquid by removing heat from it.