This actual photograph of a cut-open portion of a AX Section shows the internal ribs and swirler fins.

INTERIOR DESIGN: The picture above shows the interior of a typical Section. Integrally-cast longitudinal fins are interrupted by swirl strips for higher heat transfer efficiency. Advantages of this design are:

  1. More heat transfer surface is in contact with the process fluid within the Sections where it is normally most needed.

  2. Relationship between the various factors influencing heat transfer is improved by the use of fins and swirlers. The equivalent diameter is reduced compared to the cross section area because of the fins. Turbulent flow characteristics are maintained under virtually all conditions because of the effect of the swirlers which not only induce a turbulent action, but also have a beneficial reducing effect on the L/d Ratio resulting in a higher heat transfer rate. This turbulence also has a definite effect on keeping the interior of the Sections scrubbed clean.

  3. True radii of return bends produce gradual change in direction of flow of fluid, minimizing the effects of erosion and decreasing pressure drop.

  4. Several types of Sections with various thermal design characteristics are available, making possible an installation effecting optimum balance between heat transfer and pressure drop.

EXTERNAL DESIGN: The exterior of the Sections is planned for maximum efficiency and minimum maintenance, for sprayed or submerged service. Various factors influencing the design are:

  1. The smooth surface in contact with the cooling water presents less opportunity for heavy scaling or growths. Maintenance labor for keeping these surfaces clean is greatly reduced, compared with other types of equipment using lugs or fins on the exterior.

  2. To provide maximum water utilizations when operating in sprayed service, small collector ribs are provided at the top and bottom of the Sections. These enable the cooling water to form a thin, cohesive film with its own surface tension. This curtain of water is passed from one Section to another with a minimum of splashing and consequent water wastage.

  3. The relatively close vertical spacing between the Sections helps to maintain the water film uniformly over the Section. A unit consisting of several closely spaced stacks of Sections acts virtually as its own wind break. This provides maximum water utilization. It also reduces corrosion, because the metal is kept in a constantly wetted state. On other types of cascade cooling equipment where alternate wetting and drying is inherent, corrosion rates tend to become accelerated. In addition, these other types require extensive supporting structures and take up much more ground space for catch basin area.
Comparison with Shell and Tube H2SO4 Coolers
Design Features of Sections
Push Nipple Sections
Installation Advantages
Physical Characteristics
Type of Installations