Operating Temperature Research Articles

Torsional damper design for diesel engine: theory and application

Abstract Torsional vibration is the primary cause of engine crankshaft failure. Consequently, the reduction of engine vibration is of paramount importance for the enhancement of automotive safety and comfort. However, the lack of comprehensive insight into the damping mechanism of the torsional damper has impeded the effective control of engine torsional vibration. In order to gain insight into the vibration characteristics of the shaft system in an inline six-cylinder diesel engine, an analysis of the system’s behaviour during both free and forced vibration was conducted. A mathematical relationship was deduced between the dimensions, material, operational temperature and damping properties of the silicone oil damper. The objective was to determine the optimal damping and moment of inertia of the damper, with the aim of minimizing the torsional amplitude of the sixth harmonic. The results demonstrate a reduction in the six-harmonic torsional amplitude from 0.32° to 0.14° following the installation of the damper. The mean and relative deviations between the calculated and experimental results are 0.0018° and 0.83%, respectively. To facilitate the design of the silicone oil damper, a software program, Vibsim, was developed based on Visual Studio for the design and torsional vibration analysis of the silicone oil damper. This software is reliable in calculating results and is user-friendly.

Permanent magnets with embedded phase changing material for electric motor thermal management

The magnetic performance of NdFeB permanent magnets rapidly decreases as their operation temperature increases. This limits the power output of electric motors as their internal temperature quickly increases with the power demand. This is particularly problematic for applications where high peak power is required for a short period of time, for example during automobile highway acceleration or during an airplane lift-off. With the advances in additive manufacturing, one can envision to fabricate more complex motor geometries and magnetic structures, without additional costs, allowing for enhanced functionalities such as better thermal management. In this context, this paper investigates the feasibility of using phase changing materials (PCMs) to mitigate the temperature rise in permanent magnets (PMs) fabricated by additive manufacturing. The potential of PCM and its relevance was validated by modeling the thermal response of an electric motor during a representative electric vehicle driving scenario. It was found that segmented magnets with embedded phase changing materials would allow to efficiently control temperature rise. To validate the simulation results, PM test pieces with and without embedded PCMs were fabricated using cold spray additive manufacturing and tested using a custom laser thermal cycling setup.

Effectively Improved CH4 Sensing Performance of In2O3 Porous Hollow Nanospheres by Doping with Cd.

Recently, due to the promising application of metal oxide semiconductors in high-performance methane (CH4) sensors, more attention has been paid to the development of feasible strategies for improving CH4 sensing performance. Herein, we present a strategy of cadmium (Cd) doping to improve the CH4 sensing property of In2O3 porous hollow nanospheres (PHNSs). The Cd-doped In2O3 PHNSs were prepared via an impregnation-calcination approach with self-made carbon nanospheres as a hard template. The samples were characterized by various techniques to evaluate their structure, morphology, surface state, composition, and band gap. When applied as a sensitive material in the CH4 sensor, the Cd-doped In2O3 PHNSs, compared with bare In2O3 PHNSs, showed some significant improvements in performance, especially a reduced operating temperature (200 °C vs 300 °C), an enhanced response (9.5 vs 2.5 for 500 ppm of CH4), a faster response speed (16 s vs 276 s), and better selectivity. In addition, the Cd-doped In2O3 sensor can also maintain a commendable long-term stability, and the range of its response amplitude within 30 days is only 6.3%. The sensitization effects of the Cd dopant on the In2O3 PHNSs are discussed.

Numerical Investigation of Turbulent Convection Flow in a Rectangular Closed Cavity

Natural turbulent convection in closed cavities has many practical applications in the field of engineeringsuch as the design of electronic computer chips, atomic installation and industrial cooling among others. Inparticular, it enables in achieving a desired micro-climate and efficient ventilation in a building. Recent studiesshow that turbulent flow is affected by variations in Rayleigh numbers, aspect ratio, and heater positionamong others. Temperature is kept constant in all these studies hence inadequate literature on the effectsof temperature on a turbulent flow. In this study, aspect ratio and Rayleigh numbers are kept constant at2 and 1012 respectively and natural turbulent convection flow in a closed rectangular cavity is investigatednumerically as the operating temperature is varied from 285.5K to 293K. The rectangular cavity’s lower wallwas heated and cooling done at the top face wall while the rest of the vertical walls were kept in adiabaticcondition. Material properties such as density of the fluid kept on changing at any given temperature. Thethermal profile data generated influenced the nature of the turbulent flow. The non-linear averaged continuity,momentum, and energy equation terms were modeled by the SST k − ω model to generate streamlines,isotherms, and velocity magnitude for a different operating temperature and presented graphically. The finitedifference method and FLUENT were used to solve two SST k − ω model equations, vortices, and energy withboundary conditions. It was discovered that, as the operating temperature increased turbulence decreaseddue to a decrease in the velocity of the elements and vortices became more parallel and smaller.

Synthesis of Side-Chain Liquid Crystalline Polyacrylates with Bridged Stilbene Mesogens

In recent years, π-conjugated liquid crystalline molecules with optoelectronic functionalities have garnered considerable attention, and integrating these molecules into side-chain liquid crystalline polymers (SCLCPs) holds potential for developing devices that are operational near room temperature. However, it is difficult to design SCLCPs with excellent processability because liquid crystalline mesogens are rigid rods, have low solubility in organic solvents, and have a high isotropization temperature. Recently, we developed near-room-temperature π-conjugated nematic liquid crystals based on “bridged stilbene”. In this work, we synthesized a polyacrylate SCLCP incorporating a bridged stilbene that exhibited a nematic phase near room temperature and could maintain liquid crystallinity for more than three months. We conducted a thorough phase structure analysis and evaluated the optical properties. The birefringence values of the resulting polymers were higher than those of the corresponding monomers because of the enhanced order parameters due to the polymer effect. In addition, the synthesized polymers inherited mesogen-derived AIE properties, with high quantum yields (Φfl = 0.14–0.35) in the solid state. It is noteworthy that the maximum fluorescence wavelength exhibited a redshift of greater than 27 nm as a consequence of film formation. Thus, several unique characteristics of the SCLCPs are unattainable with small molecular systems.

Delay drift compensation of an optoelectronic oscillator over a large temperature range through continuous tuning

Phase noise reduces target sensitivity in radar and increases bit error rate in telecommunications systems. Optoelectronic oscillators are known for using optical fibre technology to realise the large delay required to attain superior phase noise performance compared to conventional microwave source technology. However, the long fibre is vulnerable to environmentally induced phase perturbations, while conventional phase shifters have insufficient range to compensate for the phase drift over the operational temperature range without the use of a temperature-controlled enclosure. Here we introduce a vector modulator controlled by a Stuart-Landau integrator, as a solution to non-efficient tuning for the phase shift. The concept is verified by simulation and experimentally demonstrated using an optoelectronic oscillator phase-locked to a system reference. Phase lock is maintained over four free spectral ranges equivalent to a tuning phase range of 1440° when the optoelectronic oscillator is cycled over a 10 °C to 85 °C temperature range. These demonstrations highlight the practical potential of our continuous tuning method.

Probing the limits for coherent optical control of a mechanically decoupled defect center in hexagonal boron nitride

The coherent control of a two-level system is among the most essential challenges in modern quantum optics. Understanding its fundamental limitations is crucial, also for the realization of next generation quantum devices. The quantum coherence of a two-level system is fragile in particular, when the two levels are connected via an optical transition, which, at the same time, enables the manipulation of the system. When such quantum emitters are located in solids the coherence suffers from the interaction of the optical transition with the solid state environment, which requires the sample to be cooled to temperatures of a few Kelvin or below. Here, we use a mechanically isolated quantum emitter in hexagonal boron nitride to explore the individual mechanisms which affect the coherence of an optical transition under resonant drive. We operate the system at the threshold where the mechanical isolation collapses in order to study the onset and temperature-dependence of dephasing and independently of spectral diffusion. The insights on the underlying physical decoherence mechanisms reveal a limit in temperature until which coherent driving of the system is possible. This study enables to increase the operation temperature of hBN-based quantum devices, therefore reducing the need for cryogenic cooling.

Innovative materials integrated with PCM for enhancing photovoltaic panel efficiency: An experimental investigation

The electrical power generated by a photovoltaic panel is crucial due to the high demand for electricity. Operating temperatures above the Standard Test Conditions (STC) negatively impact the output power, which is a significant drawback of this technology. Therefore, it is essential to keep the front and back surface temperatures of the photovoltaic panel as low as possible. Phase Change Material (PCM) is a good passive cooling method, but it has low thermal conductivity. This paper introduces a novel material to address this issue. Iron Filling Waste (IFW) is integrated with PCM to cool the photovoltaic panel. This investigation is presented experimentally with three modules. The highest surface temperature of the reference panel, 78 °C, is recorded for the uncooled module, while with PCM- IFW is 70.5 °C. The comparative analysis shows that the PV module cooled by PCM-IFW achieved an efficiency enhancement and power output increase of 39 % and 33 % respectively, compared to the reference panel without cooling. IFW-PCM achieves an average enhancement in efficiency and output power by 23 % and 11 %, respectively, compared with panels that use PCM only. Also, IFW enhances thermal conductivity without any additional economic cost for the cooling systems.

Pivotal copper bimetallic oxide in hierarchical Calcium magnesium materials for low-temperature carbon capture and utilization

Carbon removal from anthropogenic greenhouse gas emissions is essential to achieve net-zero emissions and mitigate climate change, and integrated carbon capture and utilisation (ICCU) has been studied for subsequent in-situ chemical production. However, high temperature and CaO sintering remain critical issues, highlighting the need for improved, low-cost CO2 adsorbents that can be regenerated at lower temperatures. Herin, we innovatively introduce the low-temperature ICCU coupled with reverse water gas shift reactions (RWGS) using dual functional materials (DFMs), exemplifying a range of potential transition metals doped over CaO with or without the MgO support. Among all the prepared DFMs, D-Cu showed desirable enhanced catalytic activity at a comparatively low-temperature performance (550°C) and still maintained a stable CO2 capture capacity (7.0mmol g−1) and CO yield (8.0mmol g−1) with an exceptional CO2 conversion (94.4 %) and CO selectivity (97.6 %) after cyclic hydrogenation. The mechanism study revealed that Ca2CuO3 bimetalliccatalyst in the hierarchical porous 2CaO/MgO matrix of D-Cu plays a crucial role in retaining its cyclic stability, surpassing that of noble D-Pt. Given the ICCU-RWGS performance and cyclic stability of cost-effective D-Cu at reduced operating temperatures, the findings would minimise energy and cost consumption.

The Response Time of the High Operating Temperature and Very Long Wavelength Type-II Superlattice InAs/InAsSb Interband Cascade Photodetectors

The Response Time of the High Operating Temperature and Very Long Wavelength Type-II Superlattice InAs/InAsSb Interband Cascade Photodetectors

MOF nanoflowers-based flexible portable NO sensors for human airway inflammation detection

The concentration of nitric oxide (NO) in exhaled breath is linked to respiratory diseases, requiring precise detection. Traditional two-dimensional (2D) carbon-based materials used in chemiresistive gas sensors suffer from high detection limits due to a lack of functional sites, while metal oxide sensors are limited by poor selectivity and high operating temperatures, restricting their development. Recently, metal–organic frameworks (MOFs) have emerged as an effective material for NO monitoring due to their superior selectivity; however, their inherent insulating properties hinder practical use. In this study, we synthesized Ni, Co-MOF-74-Carbon Nanotube (CNT) heterostructured nanoflowers, leveraging their bimetallic active sites and large specific surface area to enhance NO adsorption. This composite material, integrated with breathable nanofibrous membranes through physical deposition, exhibits high selection to NO, achieving a linear response range of 30 to 1000 ppb at room temperature and a limit of detection (LOD) of 18.6 ppb. This sensor can accurately detect NO levels in the exhaled breath of both healthy and diseased individuals, confirming its potential for respiratory disease diagnosis. Additionally, we developed a portable device integrating the Ni, Co-MOF-74-CNT- polyacrylonitrile (PAN) membrane, a microcontroller unit (MCU), and a Bluetooth module for real-time NO detection. The systematic design and successful validation of this portable gas sensor pave the way for future home-based real-time monitoring of airway inflammation.

Innovative heat sink design for enhanced cooling efficiency in Dual Active Bridge (DAB) topology

Abstract After in-depth research and analysis, aiming at the heat generation mechanism and limitations of the current heat dissipation method, this paper proposes an innovative heat dissipation design scheme. By optimizing the structural design of the heat sink, the heat dissipation surface area is increased, thus achieving more efficient heat emission and maintaining the optimal operating temperature of the equipment. Experimental data show that this new heat dissipation design significantly improves the cooling efficiency, an increase of about 60%, and provides support for the performance improvement of high-power power products, which brings a reliable and efficient cooling solution for related industries.

Thermoregulation and microhabitat use of Tachymenis peruviana (Dipsadidae) in semi-captivity conditions

Abstract We studied Tachymenis peruviana`s thermoregulatory strategy, and microhabitat use and selection in an open enclosure at 3400 m elevation during the wet season. We expected that thermal conditions at a high elevation locality would result in differences in the thermoregulatory efficiency within microhabitats through their use and selection along the day. We obtained preferred temperatures and critical thermal tolerance limits of field-captured individuals. Some individuals were kept in an open enclosure with access to four microhabitat types with retreats where to hide. We measured individuals’ field-body temperatures along with substrate and air temperatures, and recorded where the snakes were found according to microhabitat type and if they were inside or outside retreats. Meanwhile, operative temperatures were registered every hour at each offered microhabitat between 08:00 to 18:00 hours. The body and microenvironmental temperatures were highly correlated. Even though the enclosure offered appropriate thermal sources for snakes to reach their preferred temperatures, results indicate that the species met its energy requirements with a low effort in this high elevation enclosure. Almost three-quarters of the observations were recorded in retreat sites, showing a lower thermoregulatory efficiency compared to when they were captured aboveground. A comparative evaluation of the thermoregulation of the species in the field within a variety of thermal regimes experienced along its altitudinal and latitudinal range must still be carried out to better understand the species’ thermoregulatory strategies across the Andes.

An Exploration of Climate-Responsive Design Strategies Employed by El-Miniawy Brothers in Southern Algeria

In an age marked by globalisation, contemporary design, and diminishing regional distinctiveness, particularly concerning its impact on climate, the integration of passive strategies and climate-responsive design emerges as a critical element in forward-thinking architecture that embraces the unique climatic conditions of various locales. Consequently, this paper offers an in-depth examination of the climate-responsive design implemented by two pioneering architects who specialised primarily in housing projects in Southern Algeria. This investigation is further enriched by on-site measurements conducted on selected case studies. The findings reveal that, on typical scorching days, the actual indoor operational temperatures in 400 housing units situated in El-Oued range from 20.1 °C to 38.9 °C, whereas in 600 housing units in Ouled Djellal, temperatures fluctuate between 31.2 °C and 35.4 °C. It is noteworthy that outdoor air temperatures can soar to as high as 40 °C in El-Oued and 43 °C in Ouled Djellal during peak hours. The architectural achievements of the El-Miniawy brothers in Algeria's southern region stand as tangible examples of architecture that adeptly adapts to the harsh, arid climate. This study underscores the importance of climate-responsive design and passive strategies and offers valuable insights into the indoor thermal environment. Ultimately, this research is poised to inspire architects and decision-makers in their future housing projects.

Tailored PEO/PEG-PPG Polymer Electrolyte for Solid-State Lithium-Ion Battery

Abstract Solid polymer electrolytes (SPEs) offer a promising avenue for advancing the performance and safety of all-solid-state batteries. In this study, we investigated the effects of blending poly(ethylene oxide) (PEO) with amorphous poly(propylene glycol) (PPG) or poly(ethylene glycol-ran-propylene glycol) (PEG-PPG) to engineer SPEs with enhanced electrochemical properties. By blending PEO with PEG-PPG or PPG, we effectively lowered the crystallinity of PEO, facilitating the diffusion of lithium ions through the SPE and broadening its operational temperature range. This optimization strategy enhanced ionic conductivity and significantly reduced the interfacial resistance between the electrolyte and electrode, thus improving electrochemical stability. The solid-state lithium/lithium iron phosphate (LiFePO4 or LFP) with PEO blended with 7% PEG-PPG showed excellent charge/discharge cycling stability, with maximal discharge capacities of 165 mAh g-1 and 162 mAh g-1 at a current rate of 0.2 C at 60 and 125°C, respectively. The PEG-PPG-based SPE outperformed the PPG polymer-based SPE in terms of better electrochemical performance and a wider temperature range due to its longer polymer chain. This combination offered improved ionic conductivity, interface stability, and electrolyte compatibility with electrodes, making it highly suitable for high-demand applications of lithium-ion batteries.

An Exploration of Climate-Responsive Design Strategies Employed by El-Miniawy Brothers in Southern Algeria

In an age marked by globalisation, contemporary design, and diminishing regional distinctiveness, particularly concerning its impact on climate, the integration of passive strategies and climate-responsive design emerges as a critical element in forward-thinking architecture that embraces the unique climatic conditions of various locales. Consequently, this paper offers an in-depth examination of the climate-responsive design implemented by two pioneering architects who specialised primarily in housing projects in Southern Algeria. This investigation is further enriched by on-site measurements conducted on selected case studies. The findings reveal that, on typical scorching days, the actual indoor operational temperatures in 400 housing units situated in El-Oued range from 20.1 °C to 38.9 °C, whereas in 600 housing units in Ouled Djellal, temperatures fluctuate between 31.2 °C and 35.4 °C. It is noteworthy that outdoor air temperatures can soar to as high as 40 °C in El-Oued and 43 °C in Ouled Djellal during peak hours. The architectural achievements of the El-Miniawy brothers in Algeria's southern region stand as tangible examples of architecture that adeptly adapts to the harsh, arid climate. This study underscores the importance of climate-responsive design and passive strategies and offers valuable insights into the indoor thermal environment. Ultimately, this research is poised to inspire architects and decision-makers in their future housing projects.

A Wide‐Temperature Adaptive Electrochromic Device Based on a Poly(vinyl alcohol)/Poly(acrylic acid) Gel Electrolyte

AbstractAs a promising energy‐saving technology, electrochromic technology has been widely investigated for practical applications. However, there is relatively few research about the applications under certain extreme climatic conditions since gel electrolytes often occur freezing and volatilizing. In this work, a poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) gel electrolyte with good anti‐freezing and heat‐resistance performance is developed. Utilizing hydrated tungsten oxide (WO3·xH2O) and polyaniline (PANI) as electrochromic materials and the PVA/PAA gel as electrolyte, a WO3·xH2O/PVA/PAA‐ethylene glycol (EG)‐H2O/PANI electrochromic device (WO3·xH2O/PAEH/PANI ECD) is obtained, which can work efficiently at wide operating temperatures from −20 to 60 °C. The device has multiple reversible color changes, a large optical modulation of 66.2% at 600 nm, high coloration efficiency of 386.0 cm2 C−1, fast responses (with coloration/bleaching times of 1.3/1.1 s), as well as excellent cyclic stability (82.0% of the initial optical modulation is still retained after 2100 cycles). This work reveals the potential application prospects of PAEH gel electrolyte in practical extreme operating conditions.

Optimizing Syngas Production from Municipal Solid Waste Gasification: A Dual Reactor Fluidized Bed Study with Steam and CO2 as Gasification Agents

The escalating production of municipal solid waste (MSW) poses significant environmental and health hazards due to air, water, and soil pollution. Utilizing MSW as an energy source through gasification offers a promising solution to mitigate these impacts. This study investigates the gasification of MSW using a Dual Reactor Fluidized Bed, a thermal technology that converts solid substrates into usable gaseous fuels. The primary objective is to optimize the quality of the produced syngas by employing specific gasification agents, namely steam and CO2, and their mixtures. The research examines the effect of these agents on H2/CO ratios across a wide range of low operating temperatures, from 400°C to 700°C, using silica sand as a heat conduction medium between interconnected combustion and gasification reactors. The results demonstrate that the composition of syngas is strongly influenced by gasification temperature fluctuations. Increasing temperatures from 400°C to 700°C correlate with higher concentrations of CO and H2 in the syngas. The use of steam as a gasification agent yields H2 concentrations up to 25%, while transitioning from steam to CO2 leads to a substantial increase in CO composition, reaching 22.73%. Further analysis reveals that the H2/CO ratio decreases from 1,78 with steam and 0.64 with CO2, highlighting the crucial role of gasification agents in syngas quality. This study underscores the potential for optimizing syngas production from MSW by manipulating gasification temperatures and transitioning between different agents (steam, CO2, and their mixtures), resulting in an overall increase in the calorific value of the produced gas. These findings emphasize the opportunity to transform substantial environmental challenges associated with MSW into promising sustainable energy solutions through advanced gasification technologies.

The influence of temperature on the tribological properties of polyoxymethylene (POM) materials

Polyoxymethylene (POM) has been widely used as a gear material owing to its excellent mechanical properties. One of the key parameters that influence the tribological properties of POM is the operating temperature. In this study, the tribological properties of POM under different operating temperatures (25–110 °C) were studied. The results showed that the friction and wear coefficients tend to increase with increasing temperature. The adhesive wear is the primary wear mechanism influenced by temperature and the adhesive wear increases with an increased temperature. Material transfer was found for all the velocity and load settings.

Functionalization of ZnO Nanorods with Au Nanodots via In Situ Reduction for High-Performance Detection of Ethyl Acetate

Ethyl acetate is a critical medical indicator for detecting certain types of cancer. However, at present, available sensitive materials often exhibit drawbacks, such as high operating temperatures and poor responses to low concentrations of ethyl acetate. In this study, a ZnO nanorod sensing material was prepared using high-temperature annealing and a hydrothermally synthesized metal-organic framework (MOF) as a template. Au nanodots (AuNDs) were subsequently modified on the ZnO nanorods using an in situ ion reduction, which provided a better dispersion of Au nanodots compared with that obtained using the common reductant method. A variety of characterization methods indicate that the highly dispersed AuNDs, which possess a high catalytic activity, were loaded onto the surface as active centers, leading to a significant augmentation in the adsorption of oxygen on the surface compared with the original ZnO material. Consequently, the AuND@ZnO material exhibited heightened responsiveness to ethyl acetate at a lower operating temperature. The Au@ZnO-based sensor has a response rate (Ra/Rg) of 41.8 to 20 ppm ethyl acetate gas at 140 °C, marking a 17.4-fold increase compared with that of the original material. Due to its low power consumption and high responsiveness, AuND@ZnO is a promising candidate for the detection of ethyl acetate gas in medical applications.