Heat Exchanger Differential Thermal Expansion

Download Acrobat (PDF) Specification Sheet CMS_Design_Selection.pdf (601kb)

Heat Exchanger Designs & Selections • Differential Thermal Expansion • Pass Arrangements for Flow Through Tubes
Shell Side Fluid Flow • Impingement Plates (based on application) • Maintenance and Servicing Considerations
Principal Components • Heat Exchanger Tubes • Materials of Construction • Economic Considerations in Heat Exchanger Selection
Heat Exchanger Rating versus Expected Loads • Fundamental Heat Transfer • Load is the Measure of Heat Transferred
A Combination of Three Factors Governs Load Capacity • Heat Transfer Coefficient (U) Depends on Many Variables
Area is the Total Effective Tube Area

Differential Thermal Expansion

Since fluid in the shell is at a different temperature than the fluid in the tubes, there are corresponding differences in expansion of shell and tubes. Some provision must be made in design to compensate for this difference in thermal expansion.

“U”-Tube Design
In the “U” -tube exchanger, the shape of the tubes takes care of differential expansion. As the name implies, the tubes have a “hairpin” shape, with both ends of the tube fastened to one tubesheet. This “U” bend design allows each tube to expand and contract independently.

Floating Head Designs
This type meets the expansion problem by having one stationary tubesheet, and one free to move - “float” - back and forth as the tubes expand and contract under the influence of temperature changes.

Fixed Tubesheet Design
The fixed tubesheet heat exchanger employs straight tubes secured at both ends into tubesheets, which are welded to the shell. When a thermal expansion problem exists, an expansion joint is incorporated in the shell. This permits the shell to expand and contract.

When the possibility of intermixing of the shell side and tube side fluids cannot be tolerated, double tubesheet construction will offer positive assurance against one fluid leaking into the other at a tube to tubesheet joint. A second tubesheet is installed with a small space between tubesheets - usually open to the atmosphere.

CMS Heat Transfer Division, Inc.

273 Knickerbocker Avenue ï¿½ Bohemia, NY 11716 USA

Tel: 631-968-0084 ï¿½ Fax: 631-968-0184 ï¿½ Email: info@cmsheattransfer.com

CMS Heat Transfer products include shell and tube heat exchangers, fixed tubesheet and u-tube exchangers, oil coolers, pre-heaters, condensers, after-coolers, steam converters, kettles, reboilers and evaporators. CMS engineering include custom heat exchanger, process and mechanical design services to all TEMA and ASME conformance requirements.

IMPORTANT DISCLAIMER: All information on this site is provided for reference. While we make effort to provide accurate information, CMS cannot be held responsible for errors either of omission or typographical.

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