Shopping for a new heat exchanger? You have come to
the right place. Here you can learn about the different types of
exchangers and then order one by
calling one of the many reviewed manufacturers and retailers of heat
exchangers.
Types of Heat
Exchangers
Heat exchangers come in a large variety of types and sizes. Here are a
few of the most common ones.
Coil
heat exchangers have a long, small-diameter tube placed
concentrically within a larger tube, the combined tubes being wound or
bent in a coil. One fluid passes through the inner tube, and the other
fluid passes through the outer tube. This type of heat exchanger is
robust—capable of handling high pressures and wide temperature
differences. However these exchangers tend to be low-cost, they provide
rather poor thermal performance as a consequence of a small
heat-transfer area. A coil heat exchanger may be the best choice for
low-flow situations, for the reason that the single-tube passage creates
higher flow velocity and a higher Reynolds number. These exchangers are
generally used to establish a fixed temperature for a process-stream
sample prior to taking measurements. These exchangers can also be used
to condense high-temperature stream samples.
Plate heat exchangers consist of a stack of parallel thin plates that
lie between heavy end plates. Each fluid stream passes alternately
between adjoining plates in the stack. The plates are corrugated for
strength and to enhance heat transfer by directing the flow and
increasing turbulence. These exchangers have high heat-transfer
coefficients and area, the pressure drop is also usually low, and they
often provide very high efficiency. Nevertheless, they have
comparatively low-pressure capability.
Shell-and-tube heat exchangers consist of a bundle of parallel tubes that provide the heat-transfer surface separating the two fluid streams. The tube-side fluid passes axially through the inside of the tubes; the shell-side fluid passes over the outside of the tubes. Baffles external and perpendicular to the tubes direct the flow across the tubes and provide tube support. Tube sheets seal the ends of the tubes, ensuring separation of the two streams. The process fluid is generally placed inside the tubes for ease of cleaning or to take advantage of the higher-pressure capability inside the tubes. The thermal performance of such an exchanger generally exceeds a coil type but is less than a plate type. Pressure capability of shell-and-tube exchangers is usually higher than a plate type but lower than a coil type.