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Item Experimental and numerical investigation of nanoparticle assisted PCM-based battery thermal management system(Springer, 2024-04) Verma, Saket; Bhattacharyya, SuvanjanLi-ion batteries generate a large amount of heat in the electric vehicles. The poor heat dissipation from the battery causes temperature rise and affects its performance and life. If the battery temperature is not controlled, it may lead to serious damage to the battery cells; in extreme scenario, it may lead to fire hazards. A properly designed battery thermal management system (BTMS) controls the battery temperature ensuring its safe and efficient operation. In the present work, a nanoparticle assisted phase change material (PCM) and active cooling based BTMS technique has been investigated. The study employs both experimental and numerical approaches in the development of a water-composite PCM-based hybrid BTMS (combination of active and passive cooling techniques). Firstly, the investigation is performed to optimize the amount of PCM in the BTMS as it affects the thermal performance and mass of the system. It is found that an excess amount of PCM results in heat accumulation at the heating surface, which leads to rise in the cell temperature. The reduction in thickness of PCM from 40 to 5 mm results in 26.98% reduction in the maximum temperature. Moreover, it is found that introduction of nanoparticles between 1 and 20% (by volume) in PCM results in improved thermal conductivity. The melting fraction of PCM is improved by 29.33% and 28.0% with 20% concentration of CuO and Al2O3 in the PCM, respectively. It further helps in 70.79% improvement in the thermal non-uniformity in PCM-based hybrid BTMS.Item Experimental and numerical investigation for optimization of a hybrid battery thermal management system based on phase change material and air convection(ASME, 2024-12) Verma, SaketThis work presents the design and optimization of a phase change material (PCM)-based hybrid battery thermal management system (HBTMS). In the first stage, experiments are performed to measure the battery cell temperatures under various charge rates with and without the usage of PCM. Thereafter, a numerical model is developed to conduct a parametric study on the effect of the thickness of PCM layer around the battery cell. The results show that with the PCM thicknesses of 6–12 mm, the maximum cell temperature (36.35 °C) and thermal nonuniformity are within the safe range. In the second stage, a parametric study is conducted in the 6S1P battery module to optimize the spacing between the cells at constant inlet velocity. The result shows that an increase in cell spacing decreases the maximum temperature within the cells. The maximum temperature is within the optimal range when the cell spacing is 10 mm. At the constant cell spacing of 10 mm, an increase in inlet velocities from 0.25 m/s to 2.5 m/s gradually improves the thermal uniformity. The maximum temperature and thermal nonuniformity for the 6S1P battery module are found to be 42.07 °C and 1.17 °C respectively. In the third stage, the 6S1P battery module is optimized for PCM thickness, cell spacing, and inlet air velocity. It is found that effective thermal management is possible with PCM-based HBTMS at a low airflow rate of up to 1.5 m/s. The optimized PCM-based HBTMS shows 53.95% and 40% reductions in PCM mass and air flowrate, respectively.Item Numerical investigation of phase change material-based hybrid battery thermal management system for mass optimization(Taylor & Francis, 2023-12) Verma, SaketIn this work, a hybrid battery thermal management system using active cooling and Phase Change Material (PCM) has been studied. The additional weight of PCM poses design challenges, and hence its optimization is required. In this regard, a PCM enclosure of a cylindrical structure with six cylindrical cells is considered in 6-row and 1-column arrangement in the present work. The thermal performance of the proposed system is numerically investigated with different thicknesses of PCM layers at constant heat generation and coolant (air) flow rates. It is found that the battery thermal management with only PCM shows unsatisfactory performance under extended severe operating conditions. However, the addition low-flow convectional cooling improved the performance and the system’s reliability. It is found that for the proposed system, PCM thickness of 1 mm for the first battery cell and 2 mm for the subsequent battery cells help in better heat dissipation showing minimal thermal non–uniformity (1.1 °C) and reduced maximum temperature (39.6 °C) within the battery pack. Consequently, the optimized system shows 68.3% reduction in PCM mass as compared to the case of uniform thickness of the PCM.Item Dynamic modelling and control strategy of a temperature-driven metal hydride cooling system for buildings(Elsevier, 2025-03) Verma, SaketA temperature-driven coupled metal hydride (MH) based thermal energy storage (TES) system can allow to shave and shift the peak energy demand in buildings. The high energy density and long-term (seasonal) energy storage capability are its major advantages over other energy storage methods. The dynamic nature of the MH operation, however, requires controlled hydrogen transfer between the coupled MHs at a rate needed to meet the building’s transient load. While temperature-driven MH systems are studied in the literature, their application in buildings and control are scarcely reported. This paper presents a control-based dynamic modeling of the temperature-driven coupled MH-TES system for building cooling applications. The dynamic model is developed in MATLAB® Simulink environment, considering the thermodynamic and kinetic behaviors of the MH systems. Based on a preliminary analysis of a property database of over 337 hydrides, we select around 1600 MH pairs suitable for building cooling applications. Each of these MH pairs is studied for their performance using the dynamic model, and among all, Zr0.76Ti0.24Ni1.16Mn0.63V0.14Fe0.18–Ti0.85Zr0.15Cr1.2Mn0.8 MH pair showed fast dynamics along with high coefficient of performance (COP) of 0.71. A parametric investigation is performed on this MH pair to understand the effect of operating temperatures. Finally, three proportional-integral (PI) feedback controllers are investigated to regulate the temperature, pressure and mass exchange between the coupled MH pairs. The developed PI controller is sufficiently capable of rejecting the signal noise from the hydrogen flow and internal heat exchange processes with root mean square error of 5.78 W between reference and actual cooling load.Item Synergistic effect of binary surfactant mixture for enhanced boiling heat transfer(Elsevier, 2025-07) Verma, SaketSurfactants are ubiquitous in our everyday life ranging from household applications to various industrial applications. One such critical application is boiling, wherein, aqueous solution of surfactant is used to enhance the heat transfer coefficient (HTC) compared to pure water. However, this accompanies with the degradation in critical heat flux (CHF). While the binary mixture of surfactants has been widely investigated for its use in numerous applications, such as, corrosion inhibition, foaming, anti-toxicity, and oil and petrochemical industry, among others, its potential to enhance the boiling heat transfer performance, HTC and CHF simultaneously, remains unexplored. In this work, we investigate pool boiling heat transfer performance of aqueous solutions of individual surfactants, namely, SDS (sodium dodecyl sulfate) and DTAB (dodecyl trimethyl ammonium bromide), and their binary mixtures at various mixing ratios. Upon boiling of aqueous solution of individual surfactant, CHF significantly deteriorates. Formation of vapor foam surrounds the heater surface, due to the strong foamability, to impede the supply of fresh liquid from the bulk, leading to the deterioration in CHF. We show that the adverse effect on CHF can be mitigated with binary surfactant mixture. The adsorption dynamics at the liquid–vapor and solid–liquid interfaces are altered favorably, which reduce the foamability and enhance the wettability. Consequently, binary mixtures exhibit not only better CHF than individual surfactant solutions but also demonstrate higher HTC (%) and CHF (%), at suitable mixing ratios and concentration, in comparison to pure water. These findings highlight the potential of binary surfactant mixtures as boiling fluids and opens new area of research for other possible combination of surfactants and ionic liquids for enhanced boiling heat transfer performance.Item Analysis of grid interfaced power converter for uninterrupted hydrogen production using PEM electrolyzer(Elsevier, 2025-07) Verma, SaketPhase-shift full bridge (PSFB) converter is widely used for high-power applications in battery charging, and data centers. However, it also has a strong application for the electrolyzer system to produce hydrogen. But, in this condition, the supply power factor can be distorted due to the nonlinearity of the electrolyzer-interfaced power circuitry. Further, the electrolyzer operates relatively at a lower voltage and higher ripple-free current for its prolonged operation. Therefore, the PSFB converter can be integrated with the interleaved buck (IB) converter that has an almost steady current at its output terminal. In this study, a three-stage power converter is proposed to connect the electrolyzer with the single-phase utility grid. In the first stage, the Vienna rectifier is utilized to connect the single-phase utility grid to the electrolyzer via the cascaded PSFB-interleaved buck converter. The utility grid operates the electrolyzer and exhibits the unity power factor operation, therefore, better power quality can be ensured. Moreover, the modeling and control of the proposed configuration of the cascaded PSFB-IB power converter have been performed. As there are many active switches in the proposed converter circuit, they can be subjected to open-circuit/short-circuit faults. The faulty operation of the power converter can stop the hydrogen production leading to catastrophic failure of the complete system. Therefore, an analysis of the fault-tolerant operation of the studied cascaded converter configuration has also been performed. After the open circuit/short circuit fault occurs in any switch of the PSFB converter, the converter still operates in the symmetric half-bridge configuration, to guarantee the hydrogen as well as oxygen production. For two electrolyzer units of each rating 0.72 kW, the hydrogen and oxygen production rates are maintained at ≈ 354 L/h and ≈177 L/h, respectively under the no-fault as well as in faulty condition. The simulation of the proposed circuit is performed using the OPAL-RT OP4610 XG real-time simulatorItem Progress in design and development of battery thermal management system for electric vehicles(Springer, 2025-08) Verma, SaketReversible electrochemical batteries having reasonable cyclic charging and discharging capabilities are commonly employed in portable applications. The battery technology has improved on various aspects such as high specific energy density, high nominal voltage (up to 3.7 V), long cycle life and low self-discharge, and reached to a level, where it can be incorporated in large-scale applications, e.g. Electric Vehicles (EVs). Lithium-ion (Li-ion) batteries are commonly used in light and heavy-duty vehicles nowadays due to its superior performance, long life, and high energy density. The battery is the most critical component in an EV, and its effectiveness decides the success of the vehicle. In terms of economics, the battery pack represents a significant portion of the overall cost of an EV. Therefore, not only optimum design but also operation and maintenance of the battery pack is considered crucial. In this regard, both high and low temperatures have a significant impact on the performance of the Li-ion battery. Temperature non-uniformity also leads to capacity differences among individual cells, ultimately affecting the overall performance of the battery pack. To enhance electrochemical performance, prolong battery life, and maintain optimal power performance, it is crucial to develop a Battery Thermal Management System (BTMS) that can effectively and reasonably regulate its temperature. Most of the electrical automobile industries have adopted active cooling systems, including both air and liquid cooling. Air cooling systems are simple and low maintenance. However, due to the low heat transfer coefficient, the core part of the battery generally reaches high temperatures, leading to high thermal non-uniformity. Liquid cooling, on the other hand, has a higher heat transfer coefficient, which helps in creating a more effective cooling system. However, liquid cooling requires an external cooling system and a very effective leak-proofing, making it generally costlier. The energy provided to the active system is extracted from the battery pack, compromising the vehicle’s range. Passive cooling systems come into play as they are capable of eliminating or reducing these issues. However, passive techniques alone cannot provide effective cooling during high discharge and charging conditions. It is recommended to use a combination of passive and active techniques in BTMS to achieve the desired maximum temperature and thermal uniformity.Item Prospects of open cathode fuel cells in future powertrains(Springer, 2025-08) Verma, SaketFuel cell technology shows great potential as an eco-friendly alternative to conventional internal combustion engines. Conventional internal combustion engines only manage efficiencies of 20–30%, whereas fuel cells can attain efficiencies of up to 40–60%. In contrast to internal combustion engines (IC engines), which release pollutants into the air and worsen global warming, fuel cells only release water (or vapour) in the exhaust. Despite the fast advancements in fuel cell technology, it still lags IC engines in terms of maturity and encounters challenges such as low life, high costs, unreliability, and a lack of hydrogen refuelling infrastructure. Furthermore, fuel cell vehicles are expensive because of the high price of fuel cell stacks and hydrogen storage systems. Therefore, improving fuel cell performance and reducing costs are of utmost importance to fully utilize its potential and make it practical in future powertrains. A noteworthy advancement in clean energy technologies is open cathode fuel cells that generate power reliably and in an eco-friendly manner. There is no longer a requirement for compressed oxygen or air supply systems in open cathode fuel cells, as they offer an exposed cathode surface that allows direct access to ambient air, in contrast to typical closed cathode designs. Open cathode fuel cells are a promising alternative for several renewable energy applications due to their dependence on natural convection for oxygen delivery, which simplifies the system structure and reduces complexity. Moreover, open cathode fuel cells are more efficient at converting energy and provide more power when operated at higher temperatures. Their exceptional power density and efficiency make them ideal for transportation and distributed power generation, among other uses. However, there are still uncertainties that prevent this technology from being widely used, such as managing humidity, temperature, and durability in exposed locations. This chapter provides an overview of open cathode fuel cell technology, including its background, current uses, and potential future developments. In addition, it outlines a strategy for optimizing and characterizing the performance of open cathode fuel cells using a simplified electrochemical–thermodynamic modelling approach.