Spiral heat exchangers have received in the industry is relatively widespread, due to a number of important advantages compared to other types of heat exchangers. Spiral heat exchangers can be fabricated from any roll of material to be cold-worked and welded. Heat exchangers are compact, their design allows for complete counterflow. Cross-sectional area throughout the length of the channel remains unchanged, and the flow has no abrupt changes in direction, so that contamination of the surface of the spiral heat exchanger is less than the heat exchangers of other types, in addition, a number of designs allows for relatively easy cleaning in the case, is not required for removal sludge mechanical action. Hydraulic resistance of spiral heat exchangers at the same fluid velocity is less than that of shell and tube.

Spiral heat exchangers of various designs have been used for liquid-liquid systems, for liquid-vapor systems as condensers, evaporators and the heaters for heating and cooling of gas-vapor mixtures. Spiral heat exchangers can be arranged a special design with the distillation column and used as reflux condensers. One of the purposes of spiral heat exchangers - heating and cooling of highly viscous liquids. Since the viscous fluid flows in one channel, the problem persists even distribution of the viscous fluid through the tubes (Figure 1.37). Spiral heat exchangers can be successfully applied to liquids and sludges containing fiber materials. The use of special heat exchanger for gases is limited to small cross-section channel.

A spiral heat exchanger comprises two spiral channels wound from the web material around the central partition wall   of the core.

Figure 1.37 – Fields of coolant flow in the spiral device

By type of sealing the ends of the channels are divided into three main types:

- Dead-end channels, each of which is welded on the opposite side by means of the inserted tape. This method of sealing eliminates the possibility of mixing the heat transfer at the break pads. After removing the covers of both channels are easy to be cleaned. This method is the most common seal channels;

- Deaf channels in which the channel is sealed at the ends on both sides. The disadvantage of this type of seals is the inability to clean the channels;

- Through channels open at the ends. The seal is achieved by means of U-shaped cuff sections or sheet gasket material. Feeds of this type are easy to clean; their main drawback is the possibility of coolant flow from one channel to another.

In designs of heat exchangers and there are various combinations of the above channels. Spiral heat exchangers for imparting stiffness, especially at pressures above 0.3 MPa (3 kgf/sm²), most of the heat exchangers to one of the strips prior to winding welded pins. In addition to creating stiffness, pins fixed distance between the coils.

Spiral heat exchangers are available in two types; Type 1 with dead-end channels (with roofs) and type 2 with blind channels (without lids). Type 1 is available in four versions: horizontal heat exchanger on the feet, for liquids (Figure 1.38, a); Horizontal heat exchanger in the journals for liquids (Figure 1.38, b); vertical heat exchanger to condense the vapor journals (Figure 1.38, c); vertical heat exchanger journals for gas-vapor mixture (Figure 1.38, d).

Figure 1.38 – Spiral heat exchangers with a dead-end channels (type 1)

Type 2 is available in three versions: horizontal on the legs; horizontal trunnion; vertical on the feet (Figure 1.39). As the pads used rubber, Paronite, fluorine plastic (PTFE), asbestos board  and others.

Figure 1.39 – Vertical heat exchanger on the blind channel legs (type 2)

Spiral heat exchangers can be performed to move the spiral coolant flow over the cross-crossing the spiral flow and combined flow that combines cross and spiral flow. Constructive design of heat exchangers can be varied.

Foreign firms coiling spiral heat exchangers are made from rolled material width of 0.1 to 1.8 m and a thickness of 2 to 8 mm. Core diameter (core) 200 ... 300 mm. The channel width of 5 to 25 mm, the surface heating produced by heat exchangers from 0.5 to 160 m² . For large surface heat exchangers may be connected into blocks.

At relatively high pressures in part of the channels of foreign firms in order to reduce weight and to give sufficient strength produces coiling coils of steel of different thickness. The internal coils are wound with a smaller radius of thinner material, and the outer coils with a large radius - of greater thickness metal. Panels of different thickness are welded together at an angle, in order to seal tighter spiral coiling interfered.

In some cases, spiral heat exchangers are designed with the expectation of application of the anodic corrosion protection or protective coatings.

Spiral heat exchangers are compact and allow the creation of high velocity coolant traffic (for liquids of 1-2 m/s) at a sufficiently low hydraulic resistance.

However, these devices are complex to manufacture, may not work at pressures above 1 MPa, since the sealing of the spirals causes certain difficulties.

The advantages of the spiral heat exchangers are greater compactness (large heat exchange surface per unit volume) under the same heat transfer coefficient and flow resistance smaller for the passage of coolants, disadvantages are the complexity of their fabrication and lower density.