Corrugated tubes (DRLL)

Calculation of heat transfer and pressure drop in flow through corrugated tubes

DRLL module

Fundamentals:

In flow of liquids and gases through tubes the heat transfer and pressure drop, in addition to the fluid properties and the flow regime, are dependent to a large measure on the structure of the heat transfer surface.

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Program features:

The DRLL program calculates, based on empirical data, the heat transfer coefficient α [1], the friction factor ζ , and pressure drop Δp [2] in flow through corrugated tubes.

Price: 310 EUR plus VAT

Literature:

[1] Wärmeübergang in einphasig durchströmten Drallrohren (Heat Transfer in single-phase flow through corrugated tubes), Heat transfer information from hde Metallwerk GmbH, Menden 1994

[2] Druckabfall bei Strömungen in einseitig- und kreuzgedrallten Rohren (Pressure drop in flow through simple and cross-corrugated tubes), idem, Menden 1992

Comparison of heat exchangers with corrugated vs. smooth tubes (Design Calculation)

Corrugated tubes may be used in heat exchanger construction, so long as the fouling tendency of the medium permits, and providing the design calculation shows the heat transfer stands to be improved as a result.

The following example illustrates the difference between corrugated tubes and smooth tubes:

Water is to be heated from 90 to 110°C with 2-bar steam

A bundle with 8 rows of 30 tubes each and 3 tube-side passes is being considered

The tubes are to be Æ 13.5 x 0.7 mm

An overdesign of 15% is desired.

The calculation is performed with the AC program package using the DRLL module as an extension.

Result:

Corrugated tubes result in a 14 - 17% shorter tube length over the considered throughput range compared with smooth tubes. The pressure drop is slightly lower.

The final decision will require a cost comparison between tube costs and operating costs.

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