The answer to 'types of heat exchanger' is that there are several common types of heat exchangers used in HVAC systems. The most common are the shell and tube heat exchanger, the plate heat exchanger, and the fin and tube heat exchanger. Each type has its own advantages and is used in different HVAC applications.
The shell and tube heat exchanger consists of a series of tubes inside a shell. One fluid flows through the tubes while the other fluid flows around the outside of the tubes, allowing heat to transfer between the two fluids. Plate heat exchangers have a series of thin, corrugated metal plates with the two fluids flowing on opposite sides, maximizing the surface area for heat transfer. Fin and tube heat exchangers have a series of tubes with metal fins attached, which increases the surface area for heat exchange between the refrigerant inside the tubes and the air flowing over the fins.