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Data sets of internal resistances and open-circuit voltage of a particular battery are needed in ANSYS Fluent program to predict the heat generation accurately. However, one set of available data, called Chen's original, does not cover all types and shapes of batteries. Therefore, this research was intended to study the effects of shapes and polarization chemistries on heat generation in Li-ion batteries. Two kinds of material chemistries (nickel manganese cobalt oxide, NMC, and lithium iron phosphate, LFP) and three forms (cylindrical, pouch, and prismatic) were studied and validated with the experiment. Internal resistance was unique to each cell battery. Differences in shapes affected the magnitude of internal resistance, affecting the amount of heat generation. Pouch and prismatic cells had lower internal resistance than cylindrical cells. This may be the result of the forming pattern, in which the anode, cathode, and separator are rolled up, making electrons difficult to move. In contrast, the pouch and prismatic cells are formed as sandwich layers, resulting in electrons moving easily and lowering the internal resistance. The shapes and chemistries did not impact the entropy change. All batteries displayed exothermic behavior during a lower SOC that gradually became endothermic behavior at around 0.4 SOC onwards. [ABSTRACT FROM AUTHOR]

The thermal management system of batteries plays a significant role in the operation of electric vehicles (EVs). The purpose of this study is to survey various parameters enhancing the performance of a heat pipe-based battery thermal management system (HP-BTMS) for cooling the lithium-ion batteries (LIBs), including the ambient temperature, coolant temperature, coolant flow rate, heat generation rate, start-up time, inclination angle of the heat pipe, and length of the condenser/evaporator section. This review provides knowledge on the HP-BTMS that can guarantee achievement of the optimum performance of an EV LIB at a high charge/discharge rate. [ABSTRACT FROM AUTHOR]

Understanding the thermal characteristics of lithium-ion batteries (LIBs) under various operating situations is critical for improving battery safety. Although the application of LIBs in the real world is mostly transient, many previous models consider the phenomenon of the constant state. This study examines thermal behavior by developing a 2D electrothermal model to predict the thermal behavior of LIBs with overcharge abuse in high thermal conditions. The 18,650 cylindrical LiCoO2 graphite is investigated in a thermally controlled chamber at 35, 50, and 60 °C with a K-type thermocouple mounted on the LIB surface under charging rates of 1C, 2C, and 3C to acquire quantitative data regarding the thermal response of LIBs. Maximum critical temperatures are found at 62.6 to 78.9 °C, 66.4 to 83.5 °C, and 72.1 to 86.6 °C at 1C, 2C, and 3C, respectively. Comparing simulation analysis and experimental conditions, the highest relative error of 1.71% was obtained. It was found that relative errors increase as the charging rate increases. Moreover, increasing the charging current and surrounding temperature significantly increases the battery's surface temperature. Furthermore, battery heat distribution appears almost uniform and tends to increase towards the positive terminal because cathode material is highly resistant. In addition, increasing the LIB heat transfer coefficient could positively improve the battery performance by eventually curbing the rise in battery temperature and reducing non-uniformity. [ABSTRACT FROM AUTHOR]

Temperature stratification between outgoing hot water and incoming cold water is a key factor in diminishing energy loss during the discharging process and maximizing the useful hot water delivered from the tank or enhancing the thermal efficiency of the heating device during the heating process. In this study, the inlet structure and the obstacle plate were designed and modified based on two main factors, the reduction of inlet water velocity and the stipulation of the water recirculation area, to develop temperature stratification through the computational fluid dynamics method. The simulation model's accuracy was validated against the experimental results. The results showed that using the equalizer as an inlet pipe's auxiliary device was the best approach for decreasing the inlet water velocity, which resulted in enhancing temperature stratification. The discharging efficiency improved from 77.3% for the original tank model to 86.1% for the tank with equalizer IV model, which meant an additional 45 L of useful hot water was gained from the good temperature stratification storage tank. The installation of the obstacle plate for controlling the turbulence zone could not improve temperature stratification significantly, which resulted in an increase in discharging efficiency by only 4% more than the original tank model. [ABSTRACT FROM AUTHOR]

The fuel cell is an electrochemical energy converter that directly converts the chemical energy of the fuel into electrical current and heat. The fuel cell has been able to identify itself as a source of clean energy over the past few decades. In order to achieve the durability and stability of fuel cells, many parameters should be considered and evaluated Therefore, in this study, a single-channel high-temperature polymer exchange membrane fuel cell (HT-PEMFC) has been numerically simulated in three-dimensional, isothermal and single-phase approach. The distribution of the hydrogen and oxygen concentrations, as well as water in the anode and cathode, are shown; then the effect of different parameters of the operating pressure, the gas diffusion layer porosity, the electrical conductivity of the gas diffusion layer, the ionic conductivity of the membrane and the membrane thickness are investigated and evaluated on the fuel cell performance. The results showed that the pressure drop in the cathode channel was higher than the anode channel, so that the pressure drop in the cathode channel was higher than 9 bars but, in the anode channel was equal to 2 bars. By examining the species concentration, it was observed that their concentration at the entrance was higher and at the output was reduced due to participation in the reaction and consumption. Also, with increasing the operating pressure, the electrical conductivity of the gas diffusion layer and ionic conduction of the membrane, the performance of the fuel cell is improved. [ABSTRACT FROM AUTHOR]

Halloysite nanotube (HNT) which is cheap, natural, and easily accessible 1D clay, can be used in many applications, particularly heat transfer enhancement. The aim of this research is to study experimentally the pool boiling heat transfer (PBHT) performance of novel halloysite nanofluids at atmospheric pressure condition from typical horizontal heater. The nanofluids are prepared from halloysite nanotubes (HNTs) nanomaterials-based deionized water (DI water) with the presence of sodium hydroxide (NaOH) solution to control pH = 12 to obtain stable nanofluid. The nanofluids were prepared with dilute volume concentrations of 0.01–0.5 vol%. The performance of PBHT is studied via pool boiling curve and pool boiling heat transfer coefficient (PBHTC) from the typical heater which is the copper horizontal tube with a thickness of 1 mm and a diameter of 22 mm. The temperatures of the heated tube surface are measured to obtain the PBHTC. The results show an improvement of PBHTC for halloysite nanofluids compared to the base fluid. At 0.05 vol% concentration, HNT nanofluid has the best enhancement of 5.8% at moderate heat flux (HF). This indicates that HNT is a potential material in heat transfer applications. [ABSTRACT FROM AUTHOR]

A CFD model was performed with commercial software through the adoption of the finite volume method and a SIMPLE algorithm. SiO2-P25 particles were added to water/ethylene glycol as a base fluid. The result is considered a new hybrid nanofluid (HN) for investigating heat transfer (HT). The volume concentrations were 0.5, 1.0, and 1.5%. The Reynolds number was in the range of 5000–17,000. The heat flux (HF) was 7955 W/m2, and the wall temperature was 340.15 K. The numerical experiments were performed strictly following the rules that one should follow in HT experiments. This is important because many studies related to nanofluid HT overlook these details. The empirical correlations that contain the friction factor perform better with higher Reynolds numbers than the correlations based only on Reynolds and Prandtl numbers. When temperature differences are moderate, researchers may consider using constant properties to lower computational costs, as they may give results that are similar to temperature-dependent ones. Compared with previous research, our simulation results are in agreement with the experiments in real time. [ABSTRACT FROM AUTHOR]

Electric vehicles (EVs) are currently emerging as alternative vehicles due to their high energy efficiency and low emissions during driving. However, regarding the raising concern, the safety of EVs can further be improved before they completely replace conventional vehicles. This paper focuses on reviewing the safety requirements of EVs, especially those powered by Li-ion battery, based on the mechanical abuse tests from the international standards, national standards, regulations and other laboratories standards, and safety of occupants from the regulations and safety programs. Moreover, the publicly reported real-world fire incidents of EVs based on road crashes were collected and reviewed. The objective is to highlight the gap and challenges arose between the current safety requirements and real-world fire incidents of EVs and provide the way for assisting the future research in the area of EV safety, particularly light duty passenger vehicle. The serious challenges observed include high impact speed, multi-crashes per incident, multiple barriers of different types involved in the accident, and post-crash safety (serious injury and demise) of occupants and rescue teams. While addressing these challenges, this review will aid researchers and manufacturers working in batteries, EVs, and fire safety engineering to narrow the gap and enhance the safety of future EVs in areas of battery materials, fire extinguishing, and vehicle's body structure. [ABSTRACT FROM AUTHOR]

A comparative research on stability, viscosity (µ), and thermal conductivity (k) of carbon nanosphere (CNS) and carbon nanopowder (CNP) nanofluids was performed. CNS was synthesized by the hydrothermal method, while CNP was provided by the manufacturer. Stable nanofluids at high concentrations 0.5, 1.0, and 1.5 vol% were prepared successfully. The properties of CNS and CNP nanoparticles were analyzed with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), specific surface area (SBET), X-ray powder diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), and energy dispersive X-ray analysis (EDX). The CNP nanofluids have the highest k enhancement of 10.61% for 1.5 vol% concentration compared to the base fluid, while the CNS does not make the thermal conductivity of nanofluids (knf) significantly higher. The studied nanofluids were Newtonian. The relative µ of CNS and CNP nanofluids was 1.04 and 1.07 at 0.5 vol% concentration and 30 °C. These results can be explained by the different sizes and crystallinity of the used nanoparticles. [ABSTRACT FROM AUTHOR]

Nanofluids obtained from halloysite and de-ionized water (DI) were prepared by using surfactants and changing pH for heat-transfer applications. The halloysite nanotubes (HNTs) nanofluids were studied for several volume fractions (0.5, 1.0, and 1.5 vol%) and temperatures (20, 30, 40, 50, and 60 °C). The properties of HNTs were studied with a scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX), Fourier-transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), Raman spectroscopy and thermogravimetry/differential thermal analysis (TG/DTA). The stability of the nanofluids was proven by zeta potentials measurements and visual observation. With surfactants, the HNT nanofluids had the highest thermal conductivity increment of 18.30% for 1.5 vol% concentration in comparison with the base fluid. The thermal conductivity enhancement of nanofluids containing surfactant was slightly higher than nanofluids with pH = 12. The prepared nanofluids were Newtonian. The viscosity enhancements of the nanofluid were 11% and 12.8% at 30 °C for 0.5% volume concentration with surfactants and at pH = 12, respectively. Empirical correlations of viscosity and thermal conductivity for these nanofluids were proposed for practical applications. [ABSTRACT FROM AUTHOR]

Subcooled flow boiling is one of the major issues in the nuclear and power generation industries. If the fluid inlet temperature in the boiling area is less than the boiling temperature, the boiling process is called subcooled boiling. The symmetry of a physical system is a constant property of the system and is fixed by deformation. Using magnetohydrodynamic (MHD) forces and broken symmetry induced by nanosized particles, fluid and thermal systems can be more controlled. In this study, the effect of a magnetic field and nanoparticles on subcooled flow boiling in a vertical tube was investigated. For this purpose, a one-dimensional numerical code was used to simulate the flow and variations of various parameters that have been investigated and evaluated. The results showed that as the flow entered the heated area, the vapor volume fraction, Froude number, fluid cross-sectional area forces, mixture velocity, fluid velocity, bubble departure diameter, liquid and vapor Reynolds numbers, squared ratio of the Froude number to the Weber number, and fluid cross-sectional area forces coefficient increased. In the same region, the Eötvös number, root mean square (RMS) of the fluid cross-sectional area force, sound velocity, liquid superficial velocity, critical tube diameter, bubble departure frequency, and density of the active nucleation site were reduced. It was also observed that after the heated area and under the influence of the magnetic field and the nanoparticles, the values of the vapor volume fraction, Froude number, fluid cross-sectional area force, mixture velocity, fluid velocity, vapor, liquid Reynolds number, and squared ratio of the Froude number to the Weber number were decreased. Moreover, there was no significant effect on the Eötvös number, liquid superficial velocity, Taylor bubble Sauter mean diameter, bubble departure diameter, critical tube diameter, bubble departure frequency, or density of the active nucleation site. [ABSTRACT FROM AUTHOR]

This is the Editorial article summarizing the scope and contents of the Special Issue, Non-Equilibrium Thermodynamics of Micro Technologies. [ABSTRACT FROM AUTHOR]

An exergy analysis of a novel integrated power system is represented in this study. A Solid Oxide Fuel Cell (SOFC), which has been assisted with a Gas Turbine (GT) and Organic Rankine Cycle (ORC) by employing liquefied natural gas (LNG) as a heat sink in a combined power system is simulated and investigated. Initially in this paper, the integrated power system and the primary concepts of the simulation are described. Subsequently, results of the simulation, exergy analysis, and composite curves of heat exchangers are represented and discussed. The equations of the exergy efficiency and destruction for the main cycle’s units such as compressors, expanders, pumps, evaporators, condensers, reformers, and reactors are presented. According to the results, the highest exergy destruction is contributed to the SOFC reactor, despite its acceptable exergy efficiency which is equal to 75.7%. Moreover, the exergy efficiencies of the ORC cycle and the whole plant are determined to be 64.9% and 39.9%, respectively. It is worth noting that the rational efficiency of the integrated power system is 53.5%. Among all units, the exergy efficiency of the LNG pump is determined to be 11.7% the lowest exergy efficiency among the other investigated components, indicating a great potential for improvements. [ABSTRACT FROM AUTHOR]

We investigate the effect of viscous dissipation on the thermal transport characteristics of heat and its consequence in terms of the entropy-generation rate in a circular Couette flow. We consider the flow of a Newtonian fluid through a narrow annular space between two asymmetrically-heated concentric micro-cylinders where the inner cylinder is rotating at a constant speed. Employing an analytical methodology, we demonstrate the temperature distribution and its consequential effects on the heat-transfer and entropy-generation behaviour in the annulus. We bring out the momentous effect of viscous dissipation on the underlying transport of heat as modulated by the degree of thermal asymmetries. Our results also show that the variation of the Nusselt number exhibits an unbounded swing for some values of the Brinkman number and degrees of asymmetrical wall heating. We explain the appearance of unbounded swing on the variation of the Nusselt number from the energy balance in the flow field as well as from the second law of thermodynamics. We believe that the insights obtained from the present analysis may improve the design of micro-rotating devices/systems., Competing Interests: The authors declare no conflict of interests.