Heat exchangers play an important role in industrial settings for continuous thermal processing of liquid food products. This encompasses the interconnected fluid flow and thermal interactions where heat is transferred through the fluid flow within an enclosed volume and across the boundaries in the heat exchanger with the tube layouts. Shell-and-tube heat exchangers (STHE) are widely used in process industries including food processing. They are accounted for more than 35–40 % of all heat exchangers used in thermal processing due to their design simplicity, reliable working, and acceptable maintenance (Waleed et al., 2025). Baffle placement and tube arrangements of the STHEs have a significant effect on their performances, and thermal performance (heat transfer efficiency like the increase in the overall convective heat transfer coefficient) and pressure drops (leading to increased energy—pumping requirements) are considered as major factors for the process evaluation (Abbasian & Moradi, 2019).

Although the novel electrified technologies (e.g., continuous flow microwave heating) have been introduced in food process industry for an efficient and sustainable thermal processing, heat exchangers with STHEs still continue to have a significant role in the conventional thermal processing. Therefore, it is an important issue to consider the heat transfer efficiency connected with sustainability of these equipments, and any improvement in their designs would lead to a significant advantage for the industrial processes. Achieving an increased thermal efficiency from a STHE could mean to use a compact size heat exchanger to reach to the desired outlet temperature for the tube side fluid or using lower energy to heat the shell side fluid. Selecting a suitable shell side fluid is also expected to minimize the fouling factor and excessive fouling through the extended operational durations. Use of baffles in the shell section with a resulting complicated geometry provides structural support for the tube layout, enhances the flexibility and protects against vibration and deflection. Modification of the flow direction also enhances the heat transfer coefficient (Kakaç et al., 2012). Hence, a major objective of using baffles within the shell side is to improve thermal efficiency and to enhance secondary and vertical flows for increasing the overall convective heat transfer coefficient and heat transfer efficiency while the tube configurations and their arrangement with baffles affect the overall performance.

Segmented baffles have been conventionally used for process improvement due to their low manufacturing costs with simple installation and resulting heat transfer efficiency while they lead to significant pressure drops and strong vibrations caused by the dead zones (Hoang et al., 2025). Dead zones in STHEs are the areas where fluid velocity decreases significantly or where the fluid becomes either entirely or partially stagnant primarily due to the geometric barrier effects and flow redirection caused by the baffles. This might result in an inefficient heat transfer process with high pressure drops and strong vibrations. Conventional STHE designs with conventional segmental baffles induce sudden changes in flow direction with recirculation zones and low-velocity areas closer to the shell wall and behind the baffles (Gu, Chen, Fang, et al., 2020; Gu, Chen, Sundén, et al., 2020). These zones lead to poor fluid renewal, reduce convective heat transfer and promote fouling on heat transfer surfaces. Furthermore, incorrect arrangement of the baffles or an excessive quantity can increase the volume of dead zones (Zhang et al., 2009). Significant number of studies for STHEs have focused on baffle geometries to enhance the thermal performance. Segmental baffles represent the most common ones utilized in STHEs. They are commonly preferred by the industry because of their easy manufacturing and installation. In this context, spiral, louvered, or twisted baffles can be classified as non-segmental baffles. Novel baffle geometries are expected to offer improved efficiency and cost-effectiveness as alternatives to segmental baffles. Wang et al. (2018) compared the conventional STHEs with segmental, helical, and staggered baffles in terms of thermal performance and pressure drops. Ambekar et al. (2016) reported the STHE performance comparison for the same shell-side mass flow rate with single, double, triple segmental, helical, and flower baffles. In addition to helical baffles, two various novel baffles were presented to reduce the stagnation zones. These results reinforced the general belief that almost zero stagnation zones lead to a reduction in fouling and a long operational lifetime as the flow-induced vibration is lowered with significant increases in thermal performance. Lei et al. (2017) proposed two novel STHEs with louver baffles and higher convective heat transfer coefficients per pressure drop compared to the use of segmental baffles. Mahendran (2020) compared the conventional single plate STHE with novel baffles to present the overall heat transfer performance increase. Bicer et al. (2020) investigated the various baffle designs to substantially reduce the shell side pressure drop. El-Said et al. (2021) carried out simulations for the effect of curved baffles for their significant effects on the thermohydraulic performance. Abbasian and Moradi (2019) presented the use of disk baffles compared to segmental baffles for heat transfer performance and performance evaluation. Zhang et al. (2015) demonstrated the performance of non-continuous helical baffles with a helix angle of 10 to 30° where the 30° angle had the best integrative performance at lower mass flow rates. Recent studies also indicated the significant effect of helical baffles (Du et al., 2019; Hoang et al., 2025) while the tube layout within the STHE also played a crucial role on fluid flow and heat transfer. Helical baffles are the mostly used as they lead to a significant turbulence, reduced pressure drops, and increased heat transfer efficiencies. While the helical baffles are preferred with their significant effect on the heat transfer efficiency and reduced dead zones, their repairing costs are higher due to the complete connection to the shell for manufacturing. Hence, use of curved baffles seems to be an alternative choice with their installation and manufacturing flexibilities. A curved baffle can be manufactured by shaping a segmented baffle with a cylinder and applied force for the required dimensions for arcs at the desired radii. Production of cost and efforts in an industial appliance might be accounted to be minimal while the installation costs might be comparatively similar to the segmented baffles regarding their geometries to render them conveniently to the tube layout. Besides the use of baffles, tube layout also affects these parameters. Labbadlia et al. (2017) presented the influence of tube layout on fluid flow where 60° arrangement within the cavity had a significant number of tubes with low flow velocity while 45° arrangement secured a high velocity with maximum number of tubes. Gu, Chen, Fang, et al. (2020), Gu, Chen, Sundén, et al. (2020) designed a novel V-row triangular tube layout to increase heat transfer between adjacent tubes for the twisted elliptical tube heat exchangers. It was indicated that smaller twisted pitch of twisted elliptical tubes, larger aspect ratio, and smaller twisted pitch of twisted elliptical tubes ensured to intensify the turbulence and secondary flows. Kallannavar et al., 2020) carried out an experimental study to understand the effect of tube layouts for shell side of heat exchangers. The results of this study indicated that the 30° layout had higher heat transfer rate compared to the other layouts.

As presented in the literature review, various baffle designs have been explored compared to the conventional segmental baffles for the optimal processing. However, curved baffles might also be considered with their operational, manufacturing and repairment conveniences like the segmental baffles to better affect the shell side fluid direction and to increase the heat transfer (heat transfer coefficient) and hydraulic (pressure drops) efficiencies. Therefore, the objective of this study was to evaluate the STHE performance with the use of curved novel baffle designs and tube arrangement configurations within the heat exchanger for heat transfer enhancement (increase in the convective heat transfer coefficient) and pressure drops.