Why do the results of your software differ from those obtained with other programs?


From a principle and methodological standpoint, directly comparing the results of a general-purpose engineering software such as ours with other tools is often not fully appropriate, unless all underlying assumptions, correlations, and tuning criteria are clearly aligned.

Our software is designed to be:

  • Universally applicable, not customer-specific

  • Based on rigorous, published, and widely accepted scientific correlations

  • Developed and validated over decades of industrial experience (in the case of Shell-type exchangers, more than 25 years)

Other software tools may:

  • Be highly customized for a specific manufacturer or project

  • Include user-specific tuning based on proprietary experimental data

  • Reflect commercial adjustments rather than purely scientific calibration

Because of this, numerical agreement alone does not necessarily imply higher accuracy.

Do you allow tuning or calibration of heat transfer and pressure drop?


Yes.
Unlike some other tools, our software allows controlled and transparent calibration.

Tuning can be applied to:

  • Internal tube-side heat transfer coefficients

  • External shell-side heat transfer coefficients

  • Friction factors / pressure drop correlations

This tuning is not arbitrary. It is based on a well-known physical principle:

On a log-log plot of Reynolds number versus heat transfer coefficient, the relationship is approximately linear in most operating regimes.

Our correction factors therefore:

  • Shift the correlation curve up or down

  • Are anchored to a specific reference Reynolds number

  • Preserve the physical behavior of the correlation

This approach avoids unrealistic distortions (e.g. global correction factors of 2–3), which would have no physical meaning.

Can tuning be misused?


Like any powerful engineering tool, calibration must be used responsibly.

Tuning can be:

  • Scientific, when based on experimental or validated analytical data

  • Commercial, when forced to match a competitor’s results without physical justification

While we provide:

  • Reference guidelines

  • Reasonable bounds

  • Technical support

? Responsibility for the applied correction factors always remains with the user.

Are all programs equally flexible in tuning?


No. The level of tuning flexibility depends on the product:

  • Shell-type exchangers

    • Internal tube-side coefficients: adjustable

    • External shell-side correlations: fixed (e.g. Bell–Delaware method is not modified)

  • COILS

    • More advanced tuning options

    • Possibility to modify not only offsets but also correlation slopes

    • This feature exists but must be used with extreme caution

  • PHE

    • Separate treatment for laminar and turbulent regimes

    • Different coefficients per flow regime

What about differences of 5–10% between software tools?


In heat exchanger engineering, such differences are not only normal, but expected.

Experimental data themselves often show:

  • Repeatability errors of ±10–20%

  • In some cases, deviations exceeding ±30%

For this reason, a difference of ~10% between calculation tools is not statistically significant and should not be interpreted as an error.

A heat exchanger is not a static device that delivers a fixed output like an electrical appliance; it is a dynamic system, highly sensitive to:

  • Flow distribution

  • Velocities

  • Boundary conditions

  • Operating point

Can you adapt the software to match a specific competitor or reference?


In specific cases, yes — but this is:

  • A custom engineering activity

  • Typically based on extensive experimental datasets

  • Sometimes requiring modification of internal correlations

This type of work:

  • Is not included in standard maintenance contracts

  • May require a dedicated quotation

  • Can take months or even years of validation work

In some cases, the cost of such customization may exceed the cost of the software itself.


What information is needed to properly assess a discrepancy?


A meaningful comparison requires:

  • Full geometry definition

  • Operating conditions

  • Flow regimes

  • Reference experimental or field data

Without this information, it is not technically possible to explain differences or draw conclusions.


Final remark


Our philosophy is to provide:

  • A scientifically consistent

  • Transparent

  • Physically meaningful calculation tool



If the objective is to obtain results aligned with a specific reference or competitor, this can be evaluated — but it must be done consciously, technically, and as a dedicated activity.