Extended Surface Heat Exchangers


Customized design for various customers for centrifugal compressor Inter coolers & after coolers. Capable of cooling large volumes of air or nitrogen at minimal pressure loss. Close temperature approach to cooling water is possible. Removable bundle design with multi-pass tube side. Internal demister mounting for Wet Air condensation. Most compact and energy efficient solution for your gas cooling application.

Extended surfaces have fins attached to the primary surface on one side of a two-fluid or a multifluid heat exchanger. Fins can be of a variety of geometry—plain, wavy or interrupted—and can be attached to the inside, outside or to both sides of circular, flat or oval tubes, or parting sheets. Pins are primarily used to increase the surface area (when the heat transfer coefficient on that fluid side is relatively low) and consequently to increase the total rate of heat transfer. In addition, enhanced fin geometries also increase the heat transfer coefficient compared to that for a plain fin. Fins may also be used on the high heat transfer coefficient fluid side in a heat exchanger primarily for structural strength (for example, for high pressure water flow through a flat tube) or to provide a thorough mixing of a highly-viscous liquid (such as for laminar oil flow in a flat or a round tube). Fins are attached to the primary surface by brazing, soldering, welding, adhesive bonding or mechanical expansion, or extruded or integrally connected to tubes. Major categories of extended surface heat exchangers are Tube fin, Tube fin (Figure 1), and Tube-fin (Figure 2, individually finned tubes – Figure 2a and flat fins on an array of tubes – Figure 2b) exchangers. Note that shell-and-tube exchangers sometimes employ individually finned tubes low finned tubing (similar to Figure 2a but with low height fins) [Shah (1985)].

Basic heat transfer and pressure drop analysis methods for extended and other heat exchangers have been described by Shah (1985). An overall design methodology for heat exchangers has also been presented by Shah (1992). Detailed step-by-step procedures for designing extended surface plate-fin and tube-fin type counterflow, crossflow, parallelflow and two-pass cross-counterflow heat exchangers have been outlined by Shah (1988).