They are well suited for chilling water, soluble oil & water solutions, or thin oils. The advantages of these types of units are: They can be removed from the product for easy cleaning. They are not be damaged by the formation of ice on the evaporator's surfaces. Thus, this type of unit can be used for an ice bank application.
A DX shell-and-tube heat exchanger is not easily cleaned, therefore, it is best suited for clean fluid applications. This evaporator offers excellent heat transfer. The liquid to be chilled is pumped into the baffled shell of the vessel where it is directed back and forth over tubes that contain the cold refrigerant. This action causes a turbulent flow of the liquid, which rapidly removes the heat.
If the fluid is normally dirty or if Cleaning of the fluid side of the heat exchanger is required, then a flooded shell-and-tube heat exchanger should be used. This heat exchanger is also very efficient. Its refrigerant and liquid positions are reversed from the DX unit. The refrigerant is in the shell and the fluid to be chilled is in the tubes. This allows the tubes to be cleaned. Example
The heads of the flooded heat exchanger may be hinged. Unbolt the heads, swing them open or removing them, then allows you to run a cleaning tool through the tubes. When the tubes have been cleaned, the heads are bolted back in place, and the unit is back in service. The refrigeration side of the unit is not disturbed in this cleaning operation.