The heat exchanger system can have a huge impact on the overall energy efficiency of an industrial process. Most heat exchangers handle one “hot stream” at a relatively high temperature and one “cold stream” at a lower temperature; the temperature of the hot stream falls, while that of the cold stream rises. Simple, right? Not always.
Shell-and-tube heat exchangers (STHEs), the main workhorses in the process industries, consist of shells (pressure vessels) with bundles of tubes inside. Relatively cheap and robust, STHEs can be fabricated from a variety of materials and are typically easy to clean and maintain. They also can be designed for a wide range of sizes, operating temperatures and pressures.
An STHE has two flow paths — the “tube side” (i.e., inside the tubes), and the “shell side” (i.e., inside the shell, but outside the tubes). Depending on various factors, such as flow rates, viscosities, and propensity to fouling, we can choose to route the cold stream through the shell side and the hot stream through the tube side, or vice versa. Below we assume the hot stream is on shell side.
To learn more, read "Energy Saver: Squeeze Out The Heat" from Chemical Processing.