Jahar Sarkar

The shell‐tube heat exchanger using phase change material (PCM) is widely employed in thermal energy storage and transfer systems, but is often limited by extended charging/discharging durations. To address this, a novel shell‐and‐tube thermal energy storage featuring dual‐side discharging and single‐side charging has been designed, fabricated, and tested under three unique configurations: PCM only, PCM with fins, and PCM with both fins and metal foam. Tests were conducted across charging‐only, discharging‐only, and simultaneous charging‐discharging modes. The foam‐fin with PCM setup demonstrated superior performance, storing approximately 24% and 51% more energy during charging than the fin with PCM and pure PCM cases, respectively. It also achieved the highest combined energy storage and output, surpassing the fin with PCM case by 52% and 56%, and the pure PCM case by 126.5% and 261%, respectively. Parametric analysis also showed that an increase in the charging fluid inlet temperature significantly enhanced both energy storage and output. On the other hand, a rise in the inlet temperature of the discharging fluid led to a modest increase in stored energy, whereas a notable drop in energy output. Given its rapid thermal response and superior performance, the proposed foam‐fin with PCM integrated thermal storage is highly suitable for rooftop integration to address the variability of solar energy effectively.

Thermal shock, leg design, and current profile may also affect the transient performance and reliability of a segmented thermoelectric cooler (STEC), but it has not yet been studied. Hence, this study conducts a detailed 3-D transient analysis of STEC with two distinct leg geometries: square and circular cross-sections. Effects of various operational conditions, including pulse current profiles, segment leg ratios, and thermal shock scenarios, on the transient supercooling, coefficient of performance and thermal stress of STEC are investigated. The results indicate that the quadratic current pulse demonstrated the best cooling performance among the tested current pulse shapes, achieving temperature reductions of 5.3 K for squareleg and 6.1 K for circular-leg configurations compared to the steady-state minimum temperatures at optimal current. Additionally, the analysis highlights the influence of segment leg ratios, with a hot-side to cold-side segment length ratio of 7:3 showing improved thermal performance by achieving reduced cold-side temperature. Under thermal shock conditions, higher-power current pulses effectively minimized peak temperature rise while maintaining reasonable thermal stress levels. These findings provide valuable insights into optimizing the design and operation of STECs for hotspot cooling applications, paving the way for developing more efficient and reliable next-generation cooling systems.

Multi-objective optimization is vital for a hybrid cylindrical Li-ion battery thermal management system to balance multiple competing goals. However, this has not been explored for ternary hybrid nanofluid-cooled microchannel-integrated foam-enhanced phase change material packs. Some key design parameters and objectives were also neglected in previous optimizations. Hence, the high-fidelity numerical model is developed for multi-objective optimization of the key parameters (coolant inlet temperature, mass flow rate, microchannel spacing and metal foam porosity). Response surface methodology is employed to explore balanced compromise solutions for multiple conflicting objectives, including minimization of maximum temperature, maximum temperature difference, temperature uniformity and entropy generation. The results reveal that the inlet temperature and microchannel spacing are the most influential factors for managing temperature. Higher foam porosity enhances temperature uniformity. Optimizing inlet temperature and microchannel spacing is crucial for reducing irreversibility. Optimized inlet temperature of 300.875 K, mass flow rate of 0.2075 g/s, microchannel spacing of 6.75 mm, and metal foam porosity of 60% yield maximum temperature of 308.95 K, difference of 3.1655 K, uniformity of 0.4173 K and entropy generation of 3.98 W K⁻¹. The findings highlight the importance of strategically optimizing system parameters to achieve optimal thermal performance, reduced entropy generation, and improved cooling efficiency in battery pack designs.

Thermoelectric coolers (TECs) have emerged as promising cooling solutions; however, their relatively low coefficient of performance (COP) remains challenging. Hence, to better understand the factors influencing TEC efficiency and to guide the design of more effective systems, a three-dimensional numerical model is developed. It includes temperature-dependent thermoelectric properties (Thomson effect) and convective–radiative heat interactions. This study explores the TEC performance by analyzing various leg configurations, such as segmented and non-segmented legs, with constant and variable cross section using different material compositions to maximize the cooling effect and COP. Cylindrical legs outperformed conventional square legs, offering a 3% increase in COP and 2.5% in cooling effect. The non-segmented legs emphasize the need for condition-specific material selection, while segmented legs show up to 6.3% higher COP and 5.5% better cooling effect at lower currents, with performance declining at higher currents. A larger temperature lift between the hot and cold sides reduces TEC efficiency. The material-specific segmented leg length ratio can be optimized for maximum performance. A uniform circular leg cross section is more effective than a variable one. Incorporating the temperature-dependent material properties and the Thomson effect in the model significantly increases the TEC performance (up to 30%). Similarly, considering convective–radiative heat interaction in the model increases the performance (about 10%). These two inclusions enhance the accuracy of performance prediction of the model used in this study. These findings provide valuable insights for designing TECs according to application and operating conditions.