Heat exchanger
Also known as: plate heat exchanger, shell-and-tube heat exchanger
Short definitionA device that passes heat from one fluid to another through a metal wall, without mixing them. The evaporator and the condenser are heat exchangers too.
The fluid on the warm side gives its heat to a wall, and the cold fluid on the other face of the wall takes it. Between refrigerant and air, finned-tube coils do the work. Between refrigerant and water, the plate type made of thin stainless plates or the shell-and-tube type is used. There is also the coaxial type, made of one tube inside another.
In a project you meet it in the chiller evaporator, in heat recovery, in the glycol loop, between the two circuits of a cascade system and between the liquid and suction lines. Selection needs the capacity, the inlet and outlet temperatures on both sides, the flow rates and the allowed pressure drop. The plate type is compact but sensitive to fouling and freezing; a wrong glycol share or poor flow control leads to freeze damage.