Approach Temperature and Duty Are Different Exchanger Questions

Define the Thermal Model

The approach temperature is a local terminal gap between the exchanging streams. Alfa Laval’s heating-and-cooling FAQ identifies approach as a sizing factor. A smaller positive gap reduces the available driving force; a quoted kW figure alone does not describe the temperature program that must produce it.

Compare a Hypothetical Case

Suppose a hypothetical process must reach 59°C using a hot stream entering at 60°C. That end approach is 1 K. If the utility instead arrives at 65°C, the same requested process outlet gives 6 K. The desired outlet and duty may be unchanged, but the thermal design has a different terminal constraint.

Complete the Engineering Review

Record the closest approach for every required operating case, including the warmest cooling supply or coolest heating supply. Check the other end too; the smallest gap is not always where a summary table suggests. Keep achievable endpoints distinct from a simple heat-balance calculation, which can balance energies without validating transfer area.

For a manufacturing-vessel project, obtain the actual utility envelope. The example’s temperatures are invented and convey no HM close-approach specification. Have the exchanger supplier calculate the selected arrangement rather than importing an advertised minimum from a different equipment family.

Can the selected temperature approach coexist with the required duty and conditions?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Related Equipment References

Review the actual offered equipment and application separately from this educational example.

• manufacturing-vessel project

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Alfa Laval’s heating-and-cooling FAQ
• manufacturing-vessel project