How does short-circuiting occur in the fluid flowing through the shell side of a heat exchanger?
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Recently, while studying GB151, I haven’t been able to understand the short-circuit prevention mechanism in the shell side – how short circuits can occur there. I searched online a lot, but none of the explanations were clear to me
If the distance between the heat exchange tubes and the shell is greater than the distance between the tubes themselves, the resistance encountered by the fluid flowing in the shell side as it passes through this larger distance is lower than the resistance when it flows between the tubes. The fluid passing through this area with lower resistance cannot play a role in heat exchange between the fluids on the tube side and the shell side; thus, a short circuit occurs
The “short-circuit prevention structure for the shell side” of the tubular heat exchanger uses a baffle structure. It involves installing guide plates on the shell side. Just take a look at the schematic diagram of the shell-and-tube cooler to understand.
It turns out that in this area, the gaps are large and the resistance is low; as a result, the fluid tends to move more slowly. To encourage it to participate in heat exchange, several plates should be added here to increase the resistance
When there are no obstacles, fluids take the shortest path, which results in the least resistance. However, this prevents the liquid from reaching the areas where heat exchange should occur; this is known as short-circuiting, and it leads to situations where heat exchange cannot take place in certain areas. Therefore, baffles must be used to artificially change the flow direction of the fluid, thereby creating the largest possible area for heat exchange.