This study experimentally investigates the charging and discharging patterns of the paraffin-based phase change materials (PCM) in a shell and tube thermal energy storage system under varying operating conditions. The effects of heat transfer fluid temperature, flow rate, and system orientation were systematically assessed. The results demonstrate that system orientation and other parameters have a significant impact on thermal performance, influencing both phase change duration and energy recovery characteristics. Melting time varied between 49 and 177 min, while solidification time ranged from 397 to 680 min under various operating conditions. Although the total stored energy remained within a relatively narrow range from 225 kJ to 283 kJ. On the other hand, the recoverable energy time improved by up to 20% for inclined and vertical configurations compared to the horizontal orientation. Moreover, thermographic and visual analysis showed more detailed physical behavior of the PCM during its melting and solidification process, providing more insights into the underlying heat transfer mechanisms.

Effective thermal management in electric vehicle (EV) battery packs is critical due to heat generation during electrochemical processes and its implications for safety and performance. This study presents a three-dimensional thermal model of a cylindrical lithium-manganese oxide (Li-Mn2O4) cell to analyze heat dissipation behavior under dynamic loading. Two advanced passive cooling strategies are examined using metal foam heat sinks with differing thermal performance. The first case embeds phase change material (PCM RT25HC) within high-porosity metal foam, while the second employs metal foam structures exposed to convective cooling air. The impact of these materials on transient heat transfer is analyzed under two discharge rates: 0.5C and 1C respectively. Internal resistance variation with depth of discharge is modeled using a dynamic Internal Resistance model, which directly affects heat generation rate, defined by Joule heating. Boundary conditions assume adiabatic external surfaces, while convective heat transfer is applied through embedded channels simulating hybrid cooling. A finite volume analysis approach in Ansys Fluent is used to resolve conjugate heat transfer between battery surfaces, PCM, and porous media. Performance is evaluated by comparing the evolution of maximum and mean cell surface temperatures. Results highlight that PCM integration with porous metallic medium effectively reduces thermal gradients and delays temperature rise under high C-rate discharge, making it an effective strategy for passive battery thermal regulation.

This study presents a detailed exergetic assessment of a shell and tube latent heat thermal energy storage (LHTES) system having a five-tube heat exchanger configuration with paraffin-based phase-change material. The impact of heat transfer (HTF) mass flow rates (0.0067 to 0.02 kg s−1) on charging kinetics and thermodynamic sustainability was evaluated. The three investigated flow rates exhibited different melting characteristics, indicating that the system response depends on the operating flow rates. While the highest flow rate (0.02 kg s−1) achieved the maximum overall exergetic efficiency of 49.3

With increasing miniaturization and rising power densities of electronic devices, robust thermal management strategies are inevitable for ensuring operational stability. In the pursuit of next-generation thermal management solutions for high-density electronics, impinging jet flow (IJF) systems integrated with metal foam (MF) have emerged as a promising technique. This study investigates the interplay between pore density (measured in pores per inch or PPI), foam thickness, and flow dynamics to identify configurations that deliver optimal thermal performance. By analyzing the coupled effects of these parameters, the work aims to enhance convective heat transfer while minimizing adverse pressure losses. The investigation utilizes several key performance metrics: the average Nusselt number (Nu_avg), Colburn j-factor, Performance Enhancement Coefficient (PEC), pumping power (PP), and dimensionless power number (Np), to comprehensively assess proficient heat transfer in conjunction with hydraulic efficiency. Results reveal that lower PPI structures and increased foam thickness significantly enhance heat transfer, as evidenced by elevated Nusselt numbers resulting from intensified flow interaction and turbulence. Conversely, substrate disc plates with lower thermal conductivity exhibit reduced cooling efficiency. An empirical correlation of the form Nuavg = c1Rec2 is proposed to capture the underlying heat transfer behavior. The findings offer actionable insights into the design of compact, high-performance cooling solutions tailored for next-generation electronic systems.

Due to increasing energy demands around the globe, the excessive consumption of fossil fuels is also increasing. This situation demands new and innovative techniques to avoid further heavy usage by improving efficiency, reliability and optimization. One way to improve efficiency is to recover as much waste heat from already developed system and reuse that energy. This study investigates the use of metal foam (MF) inside the compact heat exchanger to enhance heat recovery performance. For this purpose, an experimental set has been developed using rectangular cross-sectional heat exchanger. In this counter flow heat exchanger configuration, the hot side channel remained empty, while the cold side is embedded with copper MF with pore density of 50 pores per inch (PPI). The hot-side flow rate was maintained constant at 50 NLPM, whereas the cold-side flow rate was varied between 30 and 100 NLPM. 60-Watt energy input is provided to an air-heater to introduce hot air in the hot side the heat exchanger unit. The unit is equipped with several sensors at strategic positions. The observed outcome in the form of dimensionless numbers demonstrates that by adding MF inside the heat exchanger, the heat exchanger can significantly enhance heat transfer performance. This configuration assists in recovering waste heat, thereby increasing efficiency and supporting sustainable and environmentally friendly practices.

Phase change materials are employed to store and release the heat energy at nearly constant temperatures due to their high energy capacity. However, their low thermal conductivity of PCMs make it less competent to use them as thermal energy storage materials. In this study, the heat transfer enhancement in PCM type RT-42 is numerically evaluated with the effect of system inclination. A two-dimensional model under transient condition of rectangular shell and tube TES containing five heated tubes is developed. The problem is solved by means of ANSYS Fluent to study the melting fraction, convective heat transfer coefficient, energy storage and temperature variation inside the rectangular cavity. A detailed analysis is conducted to study and compare the melting behaviour of the PCM for different positions at the inclination angles of 0o, 15o, 30o, 45o, 60o and 90o. The research concluded that the increase in inclination angle of the system enhances the heat transfer inside the TES due to the interplay between conduction and convection modes of heat transfer and the presence of buoyancy force associated with the inclination angles. The buoyancy force promotes the thermal mixing of the PCM which results in faster melting, however, there exists a temperature gradient at various positions inside the channel and this temperature gradient increases with the increase in inclination. The heat transfer at the upper half of the TES is through the convection while in the lower half, it is mainly due to the diffusion. As a result, some PCM remain unutilized throughout the heating cycle, thus requires some alternate approach for the effective PCM utilization at the bottom of the TES cavity. The configuration with high inclination angle performs better as compared to the horizontal orientation and the 90o inclination angle performed better in comparison to others which shows that besides introducing porous structures, nanoparticles or finned surfaces, the system orientation can also positively influence the heat transfer in thermal energy storages.

A detailed experimental investigation was performed to assess the potential of using porous media, specifically metal foams and packed beds, to enhance heat transfer inside compact heat exchangers relevant to the steam reformer design, which will be used in a Micro Gas Turbine-Solid Oxide Fuel Cell hybrid process later. The research utilized different porous materials, specifically metal foams and packed beds, while systematically altering critical variables such as pore densities and channel heights. Various flow rates were tested across a range of 30 to 100 standard normal Liter per minute. The performance of these configurations was compared to a baseline setup consisting of empty channels. This comparison was made using dimensionless indices, including the Nusselt-Number, Colburn j-factor and the Performance Enhancement Criterion. The study conclusively found that integrating porous media significantly increases the heat transfer coefficient. Metal foams add 2-3 times more performance as compared to the conventional heat exchanger. The results indicate the optimum configuration of the porous media for enhanced heat transfer, achieved through the interplay of pore density, porosity, permeability, flow features and geometry. The results, obtained from the experiments, are aligned closely with the previously published data, which serves to confirm the validity of the approach. Additionally, an empirical correlation was formulated for all the tested designs, which offers practical foundational approach in designing a heat exchanger with enhanced performance.

This study presents an innovative approach to sustainable construction materials by integrating bio-based phase change materials (PCMs) within recycled wood aggregates (RWAs) to develop NRG-WOOD, a novel thermal energy storage (TES) bio-aggregate. The research investigates the thermal, mechanical, and durability properties of cementitious composites incorporating NRG-WOOD, comparing their performance with traditional ordinary Portland cement (OPC) and wood-based mortars. Experimental evaluations, including hydration tests, dynamic sphere calorimetry, and mechanical strength assessments, reveal that PCM-enhanced RWAs significantly reduce hydration heat, lower energy demand, and enhance thermal regulation in buildings. Furthermore, the study extends its impact assessment through a Life Cycle Assessment (LCA) to quantify the environmental benefits of NRG-WOOD-based mortars. The LCA, conducted using SimaPro software and the Ecoinvent database, evaluates key environmental indicators such as global warming potential, embodied energy, and water footprint. This research contributes to the advancement of green building materials, offering a viable solution to mitigate climate change and transition towards more sustainable construction practices.

This numerical study proposes a hybrid cooling system design that constructs both phase change materials (PCM), which are embedded with metal foams of different morphological features and liquid cooling channels around a lithium-polymer battery. The battery is discharged at three different C-rates. The study incorporates the change of the internal resistance with respect to depth of discharge and temperature using the Generalized Reduced Gradient Algorithm, using experimental analysis. The model is implemented using the finite volume method. Results show that increasing C-rate raises both battery and PCM temperatures. The highest surface temperatures were recorded for RT35 with 40 PPI, closely matched by RT25HC with 40 PPI (epsilon = 0.9659), indicating similar heat retention at high porosity. Conversely, the lowest surface temperatures occurred with RT35 at 20 PPI (epsilon = 0.949), nearly identical to RT25HC at 20 PPI, confirming that low-porosity foams enhance thermal conductivity and cooling efficiency. PCM temperature trends mirrored the surface data, with RT35-20PPI consistently yielding the lowest values. For both PCMs, 20 PPI foams exhibited up to similar to 0.1% lower maximum surface temperatures compared to 40 PPI foams, attributed to higher effective thermal conductivity at lower porosity. RT35 generally outperformed RT25HC by maintaining similar to 0.05-0.1% cooler PCM temperatures under identical conditions, especially at low porosity. Across all configurations, the maximum temperature of the full battery volume was consistently 0.01-0.02% higher than its surface, reflecting internal heat generation dynamics. These results quantitatively demonstrate the influence of PCM type, foam porosity, and discharge rate on passive thermal management, offering a validated experimental-numerical framework for optimizing PCM-metal foam composites in battery cooling applications.

The present paper presents a pre-feasibility study for the development of a cold ironing system for cruise ships in the Italian context. The aim of the study is to understand if the development of a cold ironing system is more sustainable from the energy, environmental, and economic point of view with respect to onboard generation. To this end, a simple model is developed for the estimation of energy consumption, pollutant, and carbon emissions of a cruise ship while hotelling in port. The model allows to assess the level of consumption and emissions for both onboard generation and cold ironing. Since the parameters of the model are affected by uncertainty, a Monte Carlo analysis is also developed to understand the overall range of variability of the results. Then, a financial model is developed to estimate an appropriate tariff for the cold ironing system and to compare with the fuel cost. Results show that savings of 3ktoe/year of energy, 200 t/day of CO2, 9 M€2021 in operating cost, 12 M€2021 in externality costs can be achieved if a cold ironing system is used. Monte Carlo analysis shows that there is a probability of 95

Phase change materials (PCM) have been widely used in thermal energy storage due to their ability to absorb and release heat energy at constant temperatures. However, the enhancement in the melting process of PCMs is a key challenge in their deployment in practical applications for heat transfer. This experimental study focuses on the effect of system inclination on the melting behavior of PCM in square shell-and-tube thermal energy storage (TES). PCM inside the TES is heated using a high temperature fluid (HTF) flowing inside aluminum tubes at 55 degrees C with a constant flow rate of 2.70 l/min. It is believed that the inclination angle of the energy storage system has a positive effect on the thermal performance due to buoyancy-driven flows inside the PCM. The experiments are carried out by varying the inclination angle of the TES for 0o, 15o, 30o, 45o, 60o and 90o. Temperature variation at the key locations inside the TES has been recorded by thermocouples using a data acquisition system. Various characteristics of the PCM, such as liquid fraction, heat transfer rate by the HTF, and energy storage, have been evaluated. A simple regime map for the conduction and convection phenomenon is established based on Rayleigh Number (Ra). It is concluded that increasing the inclination angle of the TES results in a decrease in the charging time. Vertical orientation (90o) provides the optimum thermal performance among the analyzed cases for effective charging in TES, while horizontal one (0o) is the least effective.

Effective heat dissipation is essential for cooling power-intensive chips and densely packed electronics with significant heat output such as those used in data centers. This study explores the hybrid thermal management strategies that combine the use of impinging jet flow (IJF) and high-porosity metal foam (MF) heat sinks to enhance convective heat transfer. Unlike conventional jet cooling systems, the integration of metal foam introduces a highly conductive, porous medium that amplifies surface area, promotes flow mixing, and accelerates thermal diffusion - resulting in 1-2 times higher heat transfer compared to clear cases (CC). A 2D axisymmetric numerical model is developed in ANSYS Fluent using the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-epsilon turbulence model. The setup features a single circular nozzle, aluminum target plate, aluminum metal foams with air as a cooling fluid. Key parameters including nozzle-to-plate spacing (IH = 2.8-8.5), Peclet number (Pe = 2200-17,000), and foam porosity (epsilon = 0.90-0.95) - are systematically varied. The findings indicate that minimizing porosity and internal heating (IH) substantially enhances heat transfer performance. A novel correlation for average Nusselt number (Nu) has been developed, accompanied by an enhancement factor that quantifies the thermal improvement across the analyzed configurations. This work provides a robust framework for optimizing hybrid cooling systems and can be extended to explore alternative working fluids, foam geometries, and transient thermal loads in future studies.

Thermal energy storage (TES) systems have become highly relevant due to the need to cut carbon emissions, and one of the most promising TES systems is the latent heat one (LTES) based on phase change materials (PCMs). However, the low thermal conductivity and poor heat transfer capabilities of PCMs limit their performance. The LTES, which in this study incorporate phase change materials (PCMs) and metal foams, offer key benefits over traditional sensible heat storage options. The inclusion of metal foams increases the thermal conductivity of PCMs. This research examines a vertical shell-and-tube setup with a non-uniform internal tube cross-section, considering two different configurations: convergent internal tube and divergent one. It is also considered an inclination angle variation of the internal tube. In addition, it is made the assumption of external heat losses on the lateral surface. Heat transfer and phase change processes are analyzed using the Brinkman-Forchheimer-extended Darcy model and the enthalpy-porosity approach. The numerical solutions are performed through Ansys-Fluent. Findings indicate that LTES systems using metal foam and PCM have improved heat transfer, particularly in configurations with converging tube sections. Although higher heat loss during the melting, the convergent configuration has the faster melting time at each inclination angle.

Thermal management in heat exchangers is crucial in many industrial, medical, and scientific applications. However, reducing dependency on active energy sources still represents a substantial challenge. In this context, phase change materials (PCMs) offer an effective solution due to their ability to store and release large amounts of latent heat, assisting in passive thermal management. Therefore, this study proposes the use of RT42 PCM inside a box-type shell-and-tube configuration to establish the relationship between flow rate and charging and discharging behavior of PCM. In the proposed system, heat transferring fluid (HTF) water is circulated in the internal tubes at 60 °C, where the temperature is monitored by a series of thermocouples strategically placed inside the box-type configuration. To evaluate the effect of the flow of HTF on the thermal behavior of the PCM, the charging (melting) and discharging (solidification) analysis is performed by varying the water flow rate at three levels: 1.2, 0.8, and 0.4 L/min inside the laminar region (Re < 2300). A thermal camera and two webcams were used to assess the surface temperature distribution and PCM response, respectively. It was determined that increasing the flow rate accelerates charging and discharging with fluctuations in temperature curves during melting.

The present work applied the Logarithmic Mean Divisia Index methodology to decompose energy consumption in Lithuania, Poland and Slovakia by using a seven-factors equation. The equation allows to highlight the contribution of activity, structure, and intensity components on the energy consumption, jointly with other factors such as climatic conditions, energy consumption per capita, and the impact of district heating sectors which is relevant for the considered countries. Overall, it can be said that the activity component is responsible for a sharp increase in consumption. In contrast, the intensity consumption determines a strong decrease. Finally, the analysis shows that there is an overall increase in district heating consumption attributable to a decrease of the customers’ basis.