Question

For a specified fluid pair, inlet temperatures, and mass flow rates, what kind of heat exchanger will have the highest effectiveness: double-pipe parallel- flow, double-pipe counterflow, crossflow, or multipass shell-and-tube heat exchanger?

Short answer

Answer: The multipass shell-and-tube heat exchanger usually has the highest effectiveness for a specified fluid pair, inlet temperatures, and mass flow rates.

Step-by-step solution

Double-Pipe Parallel-Flow Heat Exchanger

In a double-pipe parallel-flow heat exchanger, the fluids flow in the same direction along the pipes, and heat transfer occurs between the two fluids. The performance tends to be limited as the temperatures equilibrate at lower effectiveness than other exchanger designs.

Double-Pipe Counterflow Heat Exchanger

In a double-pipe counterflow heat exchanger, the fluids flow opposite to each other, increasing the temperature difference along the heat exchanger and enhancing heat transfer between the two fluids. This design results in higher effectiveness compared to the parallel flow.

Crossflow Heat Exchanger

A crossflow heat exchanger is designed in such a way that the fluid streams flow perpendicular to each other resulting in a continuous temperature difference along the flow passages. This configuration is known for its compactness, and it can achieve relatively high effectiveness.

Multipass Shell-and-Tube Heat Exchanger

In a multipass shell-and-tube heat exchanger, fluid flow through tubes multiple times, changing direction after each pass. This design is intended to increase heat transfer effectiveness while maintaining a more compact design. The effectiveness of these heat exchangers is usually higher than that of the other three types and can be even optimized further.

Comparison and Conclusion

In summary, among double-pipe parallel-flow, double-pipe counterflow, crossflow, and multipass shell-and-tube heat exchangers, the multipass shell-and-tube heat exchanger usually has the highest effectiveness for a specified fluid pair, inlet temperatures, and mass flow rates. This is due to its design capabilities to increase heat transfer effectiveness while maintaining a more compact design compared to other configurations.