Introduction

Heat exchangers represent a key class of engineering equipment widely used across various industries. They are integral components in power generation, chemical processing, petrochemical plants, food production, vehicle cooling systems, and heating installations.
Heat exchangers are generally classified into direct-contact and indirect-contact types. Among these, recuperative heat exchangers—particularly shell-and-tube types—hold special significance. Due to their high efficiency and versatility, shell-and-tube heat exchangers are the predominant design employed in industrial applications.

Structure and operating of shell-and-tube heat exchangers

A shell-and-tube heat exchanger typically comprises the following core components:

• Shell – a cylindrical housing through which the hot or cold fluid (heat donor) flows,
• Tube bundle – an array of internal conduits where the second medium (heat recipient) circulates,
• Baffles – structural elements that enhance heat exchange efficiency by directing flow patterns within the shell,
• Inlet and outlet nozzles – connections for introducing and removing the working media.

The fundamental function of a heat exchanger is to transfer thermal energy between two fluids at different temperatures without allowing direct contact between them. This ensures both physical and chemical separation of the working media.

Optimization of Shell-and-Tube Heat Exchanger Efficiency

Shell-and-tube exchangers offer significant flexibility due to their modular construction and compatibility with standardized components. Their design is based on advanced computational methods and supported by engineering software, enabling precise adjustment of operational parameters to specific application requirements.
A key aspect in optimizing exchanger performance is the implementation of effective sealing systems, which minimize heat loss resulting from unintended fluid bypass between regions separated by the longitudinal baffle (30).

Design and functionality of longitudinal Baffle Seals

Seals in shell-and-tube exchangers play a critical role in reducing thermal losses. The main sealing challenges occur at:

• Tube sheets,
• Nozzles and flanges,
• The longitudinal baffle.

The longitudinal baffle seal is particularly crucial because the baffle edge does not form a perfect seal with the cylindrical shell. This gap allows uncontrolled medium flow, leading to energy losses and reduced thermal efficiency. This issue is resolved through the use of specialized seals such as Baffle Seal or Lamiflex types:

• JJ style Lamiflex Seal – a single-sided seal comprising a set of resilient blades mechanically fastened to the baffle via mounting holes,
• YY style Baffle Seal – a double-sided seal featuring two sets of blades housed in a metal cassette, ensuring precise alignment with both the baffle and the shell geometry.

Both sealing types are manufactured from materials resistant to high temperatures, pressure, and chemically aggressive fluids, ensuring long service life and operational reliability.

Impact of longitudinal Baffle Sealing on heat exchange efficiency

According to TEMA (Tubular Exchanger Manufacturers Association) standards, the decision to incorporate a longitudinal baffle seal is made during the design phase. We conducted numerical simulations to analyze fluid flow within the exchanger, comparing configurations with and without baffle sealing. Key findings include:

• The presence of a longitudinal baffle seal significantly restricts uncontrolled fluid flow between baffle-divided sections of the exchanger,
• The use of an appropriate seal type improves heat transfer efficiency by better utilizing the designated flow path and heat exchange surface,
• TEMA-compliant calculations show that with Baffle Seal or Lamiflex systems in place, the cross-leakage between sections is reduced by an order of magnitude—substantially improving overall exchanger performance.

Advantages of YY style Baffle Seal and JJ style Lamiflex Seal systems

• Notable increase in exchanger efficiency,
• Availability in a variety of materials to suit thermal and chemical conditions,
• Easy installation,
• Simple transport and handling (seals can be cut to length and assembled on-site). 

Conclusion

Shell-and-tube heat exchangers are critical components in thermal systems across diverse industrial sectors. Their performance can be significantly improved through targeted design optimizations—particularly by implementing effective sealing solutions. Numerical analyses and operational experience confirm that selecting the appropriate sealing system, especially for the longitudinal baffle, has a substantial impact on overall exchanger performance. Proper selection and integration of these solutions are essential to designing modern, energy-efficient heat exchange systems.

Author: Maria Libionka, Technical Sales Engineer, SPETECH^®