Editing Heat exchanger (section)

===Flow arrangements===
[[Image:Comparison of con- and counter-current flow exchange.jpg|thumb|right|A comparison between the operations and effects of a '''cocurrent and a countercurrent flow exchange system''' is depicted by the upper and lower diagrams respectively. In both it is assumed (and indicated) that red has a higher value (e.g. of temperature) than blue and that the property being transported in the channels therefore flows from red to blue. Channels are contiguous if  effective exchange is to occur (i.e. there can be no gap between the channels).]]
There are three main types of flows in a spiral heat exchanger:
* '''Counter-current Flow''': Fluids flow in opposite directions.  These are used for liquid-liquid, condensing and gas cooling applications. Units are usually mounted vertically when condensing vapour and mounted horizontally when handling high concentrations of solids.
* '''Spiral Flow/Cross Flow:''' One fluid is in spiral flow and the other in a cross flow. Spiral flow passages are welded at each side for this type of spiral heat exchanger. This type of flow is suitable for handling low density gas, which passes through the cross flow, avoiding pressure loss. It can be used for liquid-liquid applications if one liquid has a considerably greater flow rate than the other.
* '''Distributed Vapour/Spiral flow:''' This design is that of a condenser, and is usually mounted vertically. It is designed to cater for the sub-cooling of both condensate and non-condensables. The coolant moves in a spiral and leaves via the top. Hot gases that enter leave as condensate via the bottom outlet.