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Electric motor is a critical component of an electric vehicle, and proper thermal management is essential for its efficient and reliable operation. As the electric vehicle industry continues to evolve, there is a growing demand for electric motors that can deliver superior performance and high efficiency. These motors are expected to be more powerful and provide higher torque, speed, and power density to meet the performance requirements of electric vehicles; therefore, effective cooling is essential to maintain optimal motor temperature. Improper thermal management causes several issues in electric motors, including demagnetization of magnets, insulation materials aging, reduced efficiency, shorter lifespan, and motor burnout. This article presents a brief review of cooling techniques for electric motors through both numerical and experimental investigations. The researchers have evaluated various cooling techniques for electric motors, which can be broadly categorized as active cooling, passive cooling, and hybrid cooling techniques. This review highlights the temperature variations in different motor components when these cooling techniques are employed, along with the methods used to analyze the motor under different operating conditions and parameters. In conclusion, the paper recommends the most effective cooling techniques for electric motor components based on the analysis performed, providing reasons for their selection. Liquid cooling and passive cooling techniques are found to be efficient thermal management techniques for which the findings are elaborated in detail. [ABSTRACT FROM AUTHOR]

The study aims to investigate the performance of a thermal management system for lithium-ion batteries in electric vehicles (EVs) by utilizing a helical coiled pulsating heat pipe (HC-PHP) combined with a hybrid nanofluid consisting of Al2O3–MWCNT–ethylene glycol. The experimental investigation focuses on evaluating the effectiveness of this system under various operating conditions. The outcomes of this study will provide valuable insights into the influence of thermal management on power output, driving range, and safety of EVs. During a continuous discharge process at room temperature of 25 °C and discharge rates of 1C, 2C, and 3C, the lithium-ion battery’s temperature remains below 42 °C, ensuring that it does not exceed the specified safety limit. Additionally, the maximum temperature gradient across the battery, which indicates temperature variation within the battery, remains below 2 °C. These findings demonstrate the effectiveness of the thermal management system in maintaining safe and uniform temperature distribution during high-discharge operations. The observed results provide strong evidence for the exceptional heat dissipation capabilities of the thermal management system utilizing HC-PHP and an Al2O3–MWCNT–ethylene glycol-based nanofluid. The system effectively minimizes temperature gradient and enhances thermal uniformity across the battery surface. As a result, the HC-PHP ensures optimal performance of the lithium-ion battery by maintaining temperatures within the desired range of 20–50 °C, which is crucial for its reliable operation. [ABSTRACT FROM AUTHOR]

In the present research work, heat transfer and friction characteristics of in-line elliptical tubes are studied experimentally and numerically with the aiming to enhanced the thermal performance. The elliptical tubes with an aspect ratio (AR) of 0.35 and 0.50 and with circular tubes of the aspect ratio of 1 are selected for Reynolds number (Re) ranging from 5000 to 21000. The results indicate that the elliptical tube shows higher heat transfer rate with a significant reduction in the friction factor for the entire range of Reynolds number. The superior performance of the elliptical tube is often due to the aerodynamic cross-section profile of the tubes which promotes better heat transfer with a reduction in the frontal area of the tubes. The study is performed for the two different pitch to major axis ratios (PR) of 1.25 and 1.5, respectively. The results show that at a pitch ratio of 1.25 the elliptical tube with an aspect ratio of 0.50 leads to the superior heat transfer rate, while at pitch ratio of 1.50 elliptic tubes with an aspect ratio of 0.35 indicate better thermo-hydraulic efficiency relative to 0.50. [ABSTRACT FROM AUTHOR]

• Failure analysis of U-cup thermosetting polyurethane hydraulic seal is investigated using comprehensive methods. • Effect of temperature and pressure on the degradation of mechanical and chemical properties of polyurethane seal are studied. • Complete seal geometry with actual dimensions was tested in a specially designed experimental setup which created the actual field conditions. • The seal failure is expressed in terms of weakening of hydrogen bonding in the material, wear, extrusion of the seal material, and deformation analysis on the different cross-sections of seal. In the hydraulic system, investigation of seal failure is very important for reliable operation. The U-cup seal of thermosetting amorphous polyurethane material was tested to analyze the parameters causing the seal failure. Unlike the tribometer, the experiments were carried out in a novel pneumatically driven reciprocating shaft assembly by varying the pressure from 100 to 400 bar at a shaft velocity of 0.15 m/s. The changes in mechanical and chemical properties of the seal before and after tests were investigated using Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and deformation of seal dimensions. The maximum wear, extrusion, and deformation were observed at 400 bar pressure. It is found that the interfacial temperature developed due to frictional heat in the sealing zone was majorly responsible for seal degradation. Weakening of Hydrogen bonding, wear of sealing surface, extrusion due to rise in temperature, and deformation of seal dimensions were the phenomenon responsible for the seal failure. [ABSTRACT FROM AUTHOR]

Combined solar photovoltaic-thermal systems (PVT) facilitate conversion of solar radiations into electricity and heat simultaneously. A significant amount of work has been carried out on these systems since 1970. Different PVT systems have been invented in the last thirty years. Several theoretical, mathematical, numerical and experimental models are introduced by many investigators across the world. The present article gives a broad classification and review of published research work on these systems. The article mostly covers the experimental work carried out on the different types of PVT systems in the last decade. The latest technology of liquid spectrum filters for PVT systems are also explored in depth. [ABSTRACT FROM AUTHOR]

The terrestrial solar spectrum is not monochromatic; it consists of ultraviolet, visible and infrared radiations. The most commonly used single junction silicon solar cell responds to the visible and near infrared part of the solar spectrum. The ultraviolet and the infrared part of the solar spectrum causes thermal losses in the solar cell, thus reduces its electrical conversion efficiency. In order to reduce these thermal losses, and to improve the conversion efficiency of the solar cells, the concept of spectrum filtration is introduced. Use of liquid spectrum filters for photovoltaic thermal systems (PVT) is reported in some of the recent literatures. In this technique, the selective liquids are used to filter the incoming solar radiations; the desired solar spectrum for photo electricity is only allowed to enter in. The unfiltered part of the spectrum is used separately as heat for the thermal systems. The system gives heat and electricity simultaneously and it is known as Beam Split Photovoltaic Thermal System (BSPVT). The experimental feasibility of these systems has been reported in recent literatures. In the current article, an analytical approach for the performance estimation of a BSPVT system with liquid spectrum filters is reported. C-Si PV module with three different liquids as spectrum filters viz; water, silicone oil and coconut oil are considered. The mathematical analysis is based on the estimation of radiation attenuation by the liquid spectrum filters. The ‘Transmissivity Absorptivity product (τα)’ of the liquid spectrum filters is determined using Snell's law and Bouger's law. The maximum average thermal and electrical efficiency of the system are estimated as 79% and 14% respectively. The detailed analytical approach is discussed in this article. [ABSTRACT FROM AUTHOR]

The experimental and the three-dimensional numerical simulation of cross flow tube bank in staggered arrangements with and without the splitter plate attachment is performed with (5500 ⩽ Re ⩽ 14,500) and splitter plate length to tube diameter ( L / D ) ratio as 1. The longitudinal and transverse tube pitch ratio S L / D and S T / D were maintained constant as 1.75 and 2.0 respectively. The provision of the splitter plate increases the Nusselt number for the fluid flow which results in the increase in the heat transfer along with the decrease in the pressure drop within the tube bank as compared to that of the bare cylinder. The overall thermal performance of the splitter plate attachment is much superior to that of the bare cylinder which indicates higher heat transfer with lower friction factor. An increase of maximum 60–82% in the overall thermal performance was observed by the use of the splitter plate over the bare cylinder at the Reynolds number of 5500. [ABSTRACT FROM AUTHOR]

• Effect of temperature on various modes of hydraulic seal failure. • Insights to various thermal aging phenomenon which causes a hydraulic seal failure. • Study of thermal aging experiments. • Summarization of change in the mechanical properties of hydraulic seal during thermal aging. Hydraulic seal, generally made up of elastomers, is used in hydraulic systems to prevent the leakage and facilitate the efficient transmission of fluid power into mechanical power. Most of the industries dealing with fluid power consider hydraulic seal as a one of the important components. Seal failure during the operation may cause a complete shutdown of the system, downtime in production line and affect the quality of the products. Since the cost of the seal is less, replacement of seals is generally preferred when seal failure occurs. Most of the time, engineering aspects of seal failure is not considered. Understanding of seal failure mechanisms can improve the reliability of operation, life, and design of the seal. Apart from functional failure, a thermal aging phenomenon like swelling, rapid gas decompression (RGD), change in crosslink density, chain scission reaction, and wear process worsens the mechanical and chemical properties of the seal. These mechanisms can cause seal failure and are strongly governed by temperature in the sealing region. This paper explains the failure mechanism of hydraulic seal. The objective of paper is to provide a review on influence of medium to high temperature on seal failure mechanism and provide insights to improve seal performance and reliability. [ABSTRACT FROM AUTHOR]

Cross flow tube bank is an important constituent in most of the industrial heat exchanging systems such as Heating Ventilation and Air Conditioning (HVAC) systems, Waste Heat Recovery systems and Industrial Boilers. Considering the depletion of fossil fuels and allied environmental concerns, there is a huge need for improving the performance of the cross flow tube bank. The present numerical study investigates the effect of longitudinal taper fins on external flow over staggered cross flow tube bank. The longitudinal fins of various length (0.50 ≤ L/D ≤ 1.50), base thickness (0.40 ≤ T/D ≤ 0.80) and end thickness (t/D = 0.12 and 0.28) are used to evaluate the thermal performance of the tube bank. The thermal hydraulic performance is evaluated considering the effects on rate of heat transfer along with pressure drop characteristics across the tube bank. The results shows that the use of longitudinal taper fins significantly enhances the thermal hydraulic performance of cross flow tube banks. Moreover, the increase in length of fin results in an appreciable enhancement in Nusselt number, which overrules the increase in pressure drop penalty. Whereas, the increase in the fin base thickness, results in a significant reduction in pressure drop capable of compensating the reduction in Nusselt number. Hence, increase in both these dimensions results in higher thermal hydraulic performance than the bare tube bank. On the other hand, fin end thickness plays only a minor role in the finned tube bank performance. Lowering the value of fin end thickness slightly increase the thermal performance by suppressing the friction factor. [ABSTRACT FROM AUTHOR]

• The study makes use of splitter plate at the tube downstream. • The use of splitter plate increases the rate of heat transfer. • The use of splitter plate with L/D = 1.0 and above reduces pressure drop. • The overall thermo-hydraulic performance of tube bank is improved. • The correlations for Nusselt number and friction factor are developed. The use of fins for the passive mode of heat transfer enhancement is being used since decades. The use of fin increases the rate of heat transfer by increasing the effective area available for the energy exchange. Hence, most of the modern heat exchanger makes use of different types of the fins to make the device more efficient and compact. Most of the fin configuration used in the heat exchanger not only increases the rate of heat transfer but also causes an undesirable rise in pumping power owing to the additional air/fluid resistance encountered. In the present study, longitudinal fins in the form of a splitter plates are used for the experimental study in case of a staggered cross flow tube bank. The splitter plate geometric configuration such as splitter plate length (0.50 ≤ L/D ≤ 1.50) and plate thickness (0.04 ≤ t/D ≤ 0.20) are varied to further enhance the overall thermal hydraulic performance of the tube bank. The three-dimensional numerical study is also performed for better fluid flow visualization. The use of the splitter plate with L/D = 1.0 and t/D = 0.20 improves the Nusselt number with the reduction in the overall pressure drop for most of the configuration, resulting in an improvement in the thermal-hydraulic performance of tube bank. Moreover, statistical correlations are developed for the Nusselt number and friction factor characteristics for longitudinally finned tube bank for the entire range of Reynolds number from 5000 to 25000. [ABSTRACT FROM AUTHOR]

The cross-flow heat exchanger is a special type of heat exchanger involving the exchange of heat in the case of two fluids flowing in an orthogonal direction. The heat exchanger often comprises of a number of cylinders carrying hot fluid, along with the colder fluid flowing across/over the tubes or cylinders. The system also comprises of additional fins across the tube cross-section along with delta winglets so as to generate the additional turbulence for increasing the rate of heat transfer. The addition of vortex generators helps in promoting system miniaturization. Moreover, the implementation of the passive techniques in cross-flow heat exchangers significantly escalates the pumping power requirement. Thereby, the objective of this paper is to carry out a review on the recent developments and their potential candidature for improving the thermal performance of heat exchanger. The latest state-of-the-art developments are deeply discussed with its evaluating parameters and some recommendations are made for further investigation in this area. • The review of cross flow heat exchanger on passive mode is illustrated. • The effect of different tube geometry on thermal performance is presented. • The effect of different fin surface on heat transfer and pressure drop is shown. • The effect of different vortex generators on thermal performance is discussed. [ABSTRACT FROM AUTHOR]

The nanofluids are widely used for heat transfer applications in the various engineering applications. The nanoparticles dispersed uniformly in the base fluid on proper mixing. In the present study, Al2O3 and CuO nanoparticles were selected and the changes in the heat transfer coefficient were investigated in the complete laminar and discrete points of transition fluid flow through a copper tube with constant heat flux. The heat transfer coefficient was investigated at different loading of Al2O3 and CuO nanopowders ranging from 0.1% to 0.5% of volume concentration in each case for the laminar and transition fluid flow zones, which is then compared with the distilled water as a plain base fluid. It is found that the optimum enhancement in heat transfer is observed at relatively lower volume fraction of nanoparticles ranging between 0.2 to 0.3%. [ABSTRACT FROM AUTHOR]

The present work assesses the real-world performance of novel improved mud-based cookstoves (MBC) - Pavak 1 (P1) and Pavak 2 (P2) in a remote community in Khandwa, Madhya Pradesh, India. These MBC's were designed using multi-parameter optimization based on extensive laboratory testing. These MBCs are affordable and durable, and can be locally manufactured without compromising cooking quality, taste, or convenience while still meeting the Indian cookstove performance standards (BIS IS 13152 (Part 1): 2013) for emissions and efficiency. MBC's performance was compared to traditional stoves (TS) in accordance with the ISO 19869:2019 cookstove field testing protocol. 45 cooking sessions were captured (22 P1; 13 P2; 10 TS). Fuel-based emission factors (EF) for PM 2.5 and CO were estimated using the carbon balance method. Results indicate reductions in PM 2.5 (56% for P1 and 46% for P2) and CO emissions (15% for P1 and 0.85% for P2) compared to TS. Analysis of real-time modified combustion efficiencies showed that MBCs exhibited prolonged periods in pure flaming conditions compared to TS. A user perception survey was conducted in the intervention households to understand community acceptability. Our results demonstrate the potential for increased adoption rates, emphasizing the importance of information, education, and communication (IEC) programs to maximize health and climate benefits. [ABSTRACT FROM AUTHOR]

Magnetic binary oxide particles (MBOP) were prepared by template method using chitosan in the laboratory for the removal of As(III) from water. The prepared MBOP has super paramagnetic property which is sufficient for magnetic separation. Column study was performed at two different flow rates of 2.0 ml/min and 5.0 ml/min and comparison was made with regenerated MBOP, commercial activated carbon and commercial activated alumina. It is observed that fresh MBOP has higher breakthrough time and capacity than regenerated MBOP by a factor of 1.25 and 1.37 respectively. In Logit method, the values of K (adsorption rate constant) and N (adsorption capacity coefficient) were obtained as 0.2066 (L/mg h) and 1014 (mg/L) for 5.0 ml/min flow rate. All the drinking water parameters are within the limit of BIS 10500-2012. Toxicity characteristic leaching procedure (TCLP) and semi dynamic tests were performed for the mix ratios of 01:02:01, 01:02:05 and 01:02:10 and were found safe for the disposal. [ABSTRACT FROM AUTHOR]