The paper presents a survey of the experimental and numerical studies of shell-and-tube systems in which phase change material (PCM) is used. Due to the multitude of design solutions for shell-and-tube systems, the emphasis is placed on double-tube (DT), triplex-tube (TT), and multi-tube (MT) units. Additionally, only single-pass systems are considered. Particular attention is paid to the method of heat transfer intensification. The analysis of the research results begins with the classification of each of the three mentioned systems. The systems are divided according to the angle of inclination, the method of heat transfer enhancement (HTE), the flow direction of heat transfer fluid (HTF), and the arrangement of tubes in the bundle. Moreover, the simplified schemes of the particular research cases are proposed. Then, the works on each of the mentioned systems, i.e., DT, TT, and MT, are discussed chronologically. Finally, in the corresponding tables, details of the discussed cases are presented, such as geometric dimensions, and the type of PCM or HTF used. A novelty in the present work is the precise classification of PCM TESUs as DT, TTH, and MTH. In the literature, there is a lot of discretion in this regard. Second, the methods of heat transfer intensification in the presented PCM TESUs are listed and discussed. Third, unified schemes of design solutions for the discussed PCM TESUs are proposed. The review shows that development directions for shell-and-tube TESUs include systems with high conductivity fins of different shapes, heights, and spacing, several PCMs, and modified shells.

The results of a comprehensive study on the charging and discharging of latent heat storage systems (LHSS) are presented. Multi-tube shell-and-tube units with variable layouts of tube bundles are examined. Two tube arrangements—in-line and staggered—are tested. A variable number of tubes and different tube positions in a bundle are investigated. Moreover, two pitch ratios are studied. Three commercially available substances are used as phase change materials (PCM). The results show that increasing the number of tubes reduces both the charging and discharging times. It is found that for a bundle of seven tubes with a pitch ratio s/d = 4.5, the in-line tube arrangement results in a shorter charging time, but the discharging time is shorter for a staggered tube arrangement.

The following study investigated the melting behavior of coconut oil as a phase-change material in shell-and-tube and shell-and-coil thermal energy storage systems. The primary objective was to deepen the understanding of PCM melting dynamics under varying boundary conditions, aiming to optimize TES designs for renewable energy applications. This research addresses a gap in understanding how different heat-transfer configurations and boundary conditions affect melting efficiency. Experimental setups included two distinct heat-transfer surfaces in a cylindrical shell—a copper tube and a copper coil—tested under constant wall temperatures (34 °C for the tube, 33 °C for the coil) and constant heat flux (597 W/m² for the coil). Findings reveal that melting under constant heat flux takes approximately twice as long as under constant wall temperatures, underscoring the critical role of heat-transfer conditions in TES performance. The liquid fraction was estimated using two approaches: image-based analysis and the volume-averaged temperature method. The former proved less reliable due to geometric limitations, particularly when the heat-transfer surface was distant from the shell wall. Conversely, the latter yielded higher accuracy, especially in the shell-and-tube setup. Due to the scarcity of correlations for constant heat-flux conditions, the novel contribution of this work is the development of a modified semi-empirical correlation for the shell-and-coil TES system. For this purpose, an existing model, which demonstrated strong alignment with experimental data, was adapted. The findings suggest that slower melting under constant heat flux could benefit applications needing sustained heat release, like solar energy systems. Future work could investigate additional PCMs or novel geometries to further improve TES efficiency and scalability.

Various types of heat pipes are available to purchase off the shelf, from various manufacturers, but most of them have strictly defined geometry and technical parameters. However, when there is a need to use a heat pipe (HP) with an unusual size and shape or working conditions other than the standard ones, it becomes very costly to order them from manufacturers, especially in small quantities, and only a few producers are willing to fulfill such an order. This paper presents a detailed description and step-by-step method of manufacturing and testing a low-cost HP with specific properties and geometry, cooperating with a modular heat recovery system based on the use of phase change materials (PCM) for electromobility applications. The presented heat pipes were made entirely by hand, primarily with the use of basic workshop tools, without the use of specialized and automated CNC machines. Utensils used during the process were either made by hand or using desktop FDM 3D printers. During the evaluation of heat pipes’ performance within PCM (coconut oil), simple statistical functions were used. One-dimensional and two-dimensional histograms were used to visualize data obtained during this research. The presented method allows the manufacturing of heat pipes that are, on average, able to melt about 35% more PCM than an empty copper pipe with the exact same geometry. The HPs’ performance in coconut oil was evaluated on the basis of their future applications.

This paper presents the results of calculations of the shell-side heat transfer coefficient and pressure drop for a shell-and-tube heat exchanger with an inner shell diameter of 200.2 mm and an effective tube length of 518 mm. The exchanger contained 85 copper tubes (12/10 mm), arranged in a staggered layout with a pitch ratio of 1.5. It was equipped with nine segmental baffles, with a 25% baffle cut and a baffle spacing of 48 mm. The inlet temperature of the hot water flowing through the shell, and the mass flow rate, were varied in the ranges of 35–79 °C and 1–3 kg/s, respectively. The calculations were performed using the extended Bell–Delaware method, the VDI (Gaddis–Gnielinski) method, and the Aspen Exchanger Design and Rating. CFD simulations were performed using the OpenFOAM and Ansys Fluent software packages. The calculated results were then compared with the available experimental data. The findings showed that the VDI method generated the greatest overestimation of the heat transfer coefficient and underestimated the pressure drop, whereas the extended Bell–Delaware method demonstrated the highest agreement with the experimental data.