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A polyaniline (PANI)/tin oxide (SnO2) composite for a CO sensor was fabricated using a composite film composed of SnO2 nanoparticles and PANI deposition in the present study. Tin oxide nanoparticles were synthesized by the sol-gel method. The SnO2 nanoparticles provided a high surface area to significantly enhance the response to the change in CO concentration at low operating temperature (<75 °C). The excellent sensor response was mainly attributed to the relatively good properties of PANI in the redox reaction during sensing, which produced a great resistance difference between the air and CO gas at low operating temperature. Therefore, the combination of n-type SnO2 nanoparticles with a high surface area and a thick film of conductive PANI is an effective strategy to design a high-performance CO gas sensor.

Thermoelectric generators (TEGs) are a form of energy harvester and eco-friendly power generation system that directly transform thermal energy into electrical energy. The thermoelectric (TE) method of energy harvesting takes advantage of the Seebeck effect, which offers a simple solution for fulfilling the power-supply demand in almost every electronics system. A high-temperature condition is commonly essential in the working mechanism of the TE device, which unfortunately limits the potential implementation of the device. This paper presents an in-depth analysis of TEGs at low operating temperature. The review starts with an extensive description of their fundamental working principles, structure, physical properties, and the figure of merit (ZT). An overview of the associated key challenges in optimising ZT value according to the physical properties is discussed, including the state of the art of the advanced approaches in ZT optimisation. Finally, this manuscript summarises the research status of Bi2Te3-based semiconductors and other compound materials as potential materials for TE generators working at low operating temperatures. The improved TE materials suggest that TE power-generation technology is essential for sustainable power generation at near-room temperature to satisfy the requirement for reliable energy supplies in low-power electrical/electronics systems.

Expecting to gain an excellent operating temperature window and superior catalytic activity of the catalyst in SCR reaction, the Fe-Ce bimetallic oxide catalyst was firstly prepared and sulfated with two different sulfation strategies by H 2 SO 4 . It is interestingly found that both the two sulfation strategies can significantly broaden the operating temperature window of the catalyst. In particular, the SFC and FCS both exhibit superior resistance to H 2 O + SO 2 , and the NO x conversion of the SFC even displays no changes in the coexistence of H 2 O and SO 2 . The characterization results show that different sulfation strategies can generate amorphous sulfate species rather than bulk sulfate species. Furthermore, more surface-adsorbed oxygen as well as higher contents of Ce 3+ and Fe 3+ can be obtained on the sulfated catalysts, especially for the SFC catalyst. Meanwhile, different sulfation strategies will progressively enhance the redox ability and amounts of strong acid sites, which will contribute to broadening the operating temperature window for the NH 3 -SCR reaction. Additionally, different sulfation methods do not change the reaction pathway of catalysts. However, the adsorption of ad-NH 3 species and reactivity of ad-NO x species are significantly changed. These lead to the reaction pathway shifts to E - R direct over the SFC and the promotion of E - R and L – H mechanisms over the FCS catalyst.

The aim of this study is to enhance the energy performance of PV modules in the Ghardaïa region of Algeria by using an additive PCM (CaCl 2 ·6H 2 O). The experimental configuration is set up to provide efficient cooling by reducing the operating temperature of the PV module’s rear surface. The PV module operating temperature, output power, and electrical efficiency for both cases with PCM and without PCM have been plotted and analyzed. In the experiments, it was found that using phase change materials improves the energy performance and output power of PV modules by reducing their operating temperature. In comparison to the PV-PCM module without PCM, the average operating temperature is reduced by up to 20 °C. Besides, PV modules with PCM have an average power of 46.11% higher than PV modules without PCM. The electrical efficiency of PV module with PCM is on average 6% higher than the configuration without PCM.

The flexible lithium-ion batteries (LIBs) are revolutionizing the consumer market mandatory due to their versatility, high energy and power density, and lightweight design. The rising demand of expedient electronic and wearable devices has driven the widespread application of these flexible batteries in view of convenience and efficiency for users. The market demand for next-generation devices has incited the innovative investigation on novel flexible lithium-ion batteries to fulfill evolving needs. In this study, the performance of flexible lithium-ion battery made with PLA-graphite/graphite semi-solid electrodes has been investigated. The semi-solid electrodes were prepared by combining the active and conductive electrode materials with the liquid electrolyte. This setup of viscous and thick slurry enabled an efficient movement for all solid particles within the battery with the application of bending, shear, or pressure forces. In order to investigate the battery’s enactment, the heterogeneous 3D model was developed with the consideration of all electrical and electrochemical parameters of semi-solid electrodes. The COMSOL Multiphysics® software was employed for the finite element analysis (FEA) of the governing equations. The specific discharge capacity of the proposed model has been validated with the experimental results under half- and full-cell modes. Furthermore, the deformation characteristics, battery discharge rate, and operating temperature have been examined using the model of flexible electrodes under half- and full-cell modes. The results of this study suggested the level of optimal functional temperature and rate of discharge for the flexible LIB.

High operating temperature (HOT) detectors, especially state-of-the-art HgCdTe detectors, hold promise for significantly reducing the weight and cost of infrared (IR) detectors. However, HgCdTe detectors suffer from high dark current density dominated by Auger recombination at high working temperatures due to high carrier concentrations. An extremely low doping level is required to decrease the carrier concentration, which is difficult to achieve by molecular beam epitaxy (MBE) due to uncontrollable substrate impurities and equipment background impurities, among other factors. Carriers can also be significantly reduced by creating non-equilibrium working conditions in the HgCdTe detector, where the resulting detector can achieve a low dark current. That dark current is influenced by the thickness and doping level of the absorbers. Herein, we investigated the effects of absorber layer thickness and doping concentration on the dark current of a non-equilibrium photovoltaic long-wavelength (LW) IR HgCdTe detector using Silvaco ATLAS software. It was revealed that the dark current was significantly influenced by the doping level, and a prohibitively low level of doping (5 × 1013 cm−3) was usually required to retain the low dark current. The thickness of the absorber layer could be appropriately designed under a certain doping concentration. Moreover, a higher quantum efficiency via a thinner absorber layer could be achieved by designing an appropriate composition gradient, which effectively increased the signal-to-noise ratio of the detector. This work shows that a high-performance HOT non-equilibrium LW HgCdTe detector can be achieved by optimizing the absorber thickness and Cd composition gradient slope under a relative high doping concentration (1 × 1014 cm−3).

LaFeO 3 (LFO) particles were synthesized by citrate sol–gel method and characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and specific surface and pore size analysis instrument. To investigate the formaldehyde (HCHO)-sensing properties, the side-heating gas sensor based on LFO particles was fabricated. The LFO particle-based gas sensor presented high response and good selectivity to HCHO at an operating temperature of 100 °C. At the range of 1–50 ppm HCHO, the LFO particle-based gas sensor exhibits a nearly linear response, and the linear correlation coefficient is 0.99. The response time and recovery time are about 33 and 27 s, respectively. The results indicate that LFO particles synthesized by citrate sol–gel method have potential applications for fabricating high-performance and low power consumption HCHO gas sensor. Graphical Abstract

Fuel cells, propulsion systems, and reaction control systems (RCSs) are just a few of the space applications that depend on pressure vessels (PVs) to safely hold high-pressure fluids while enduring extreme environmental conditions both during launch and in orbit. Under these challenging circumstances, PVs must be lightweight while retaining structural integrity in order to increase the efficiency and lower the launch costs. PVs have significant challenges in space conditions, such as extreme vibrations during launch, the complete vacuum of space, and sudden temperature changes based on their location within the satellite and orbit types. Determining the operational temperature limits and endurance of PVs in space applications requires assessing the combined effects of these factors. As the main propellant for satellites and rockets, hydrogen has great promise for use in future space missions. This study aimed to assess the structural integrity and determine the thermal operating limits of different types of hydrogen pressure vessels using finite element analysis (FEA) with Ansys 2019 R3 Workbench. The impact of extreme space conditions on the performances of various kinds of hydrogen pressure vessels was analyzed numerically in this work. This study determined the safe operating temperature ranges for Type 4, Type 3, and Type 1 PVs at an operating hydrogen storage pressure of 35 MPa in an absolute vacuum. Additionally, the dynamic performance was assessed through modal and random vibration analyses. Various aspects of Ansys Workbench were explored, including the influence of the mesh element size, composite modeling methods, and their combined impact on the result accuracy. In terms of the survival temperature limits, the Type 4 PVs, which consisted of a Nylon 6 liner and a carbon fiber-reinforced epoxy (CFRE) prepreg composite shell, offered the optimal balance between the weight (56.2 kg) and a relatively narrow operating temperature range of 10–100 °C. The Type 3 PVs, which featured an Aluminum 6061-T6 liner, provided a broader operational temperature range of 0–145 °C but at a higher weight of 63.7 kg. Meanwhile, the Type 1 PVs demonstrated a superior cryogenic performance, with an operating range of −55–54 °C, though they were nearly twice as heavy as the Type 4 PVs, with a weight of 106 kg. The absolute vacuum environment had a negligible effect on the mechanical performance of all the PVs. Additionally, all the analyzed PV types maintained structural integrity and safety under launch-induced vibration loads. This study provided critical insights for selecting the most suitable pressure vessel type for space applications by considering operational temperature constraints and weight limitations, thereby ensuring an optimal mechanical–thermal performance and structural efficiency.

A two-dimensional (2D) Dy2O3-Pd-PDA/rGO heterojunction nanocomposite has been synthesised and tested for hydrogen (H2) gas sensing under various functioning conditions, including different H2 concentrations (50 ppm up to 6000 ppm), relative humidity (up to 25 %RH) and working temperature (up to 200 °C). The material characterisation of Dy2O3-Pd-PDA/rGO nanocomposite performed using various techniques confirms uniform distribution of Pd NPs and 2D Dy2O3 nanostructures on multi-layered porous structure of PDA/rGO nanosheets (NSs) while forming a nanocomposite. Moreover, fundamental hydrogen sensing mechanisms, including the effect of UV illumination and relative humidity (%RH), are investigated. It is observed that the sensing performance is improved as the operating temperature increases from room temperature (RT = 30 °C) to the optimum temperature of 150 °C. The humidity effect investigation revealed a drastic enhancement in sensing parameters as the %RH increased up to 20%. The highest response was found to be 145.2% towards 5000 ppm H2 at 150 °C and 20 %RH under UV illumination (365 nm). This work offers a highly sensitive and selective hydrogen sensor based on a novel 2D nanocomposite using an environmentally friendly and energy-saving synthesis approach, enabling us to detect hydrogen molecules experimentally down to 50 ppm.

Gas turbines have been widely used in power generation and aircraft propulsion. The turbine inlet temperature may be elevated than the metal melting point for improving the gas turbine performance. Therefore, cooling of gas turbines becomes very critical for engine operation and safety. Blade cooling is an important parameter in order to increase the turbine blade life for reaching a temperature. To combat and avert failure of turbine blades in gas turbine engines resulting from the excessive operating temperatures, film cooling has been incorporated into blade designs. Normally in film cooling, cool air is bled from the compressor stage. In this work, the cool air will bleed from the air cycle machine’s output and ducted to the internal chambers of the turbine stator blades and discharged through small holes. Air cycle machine output temperature range from 10°C to -20°C. Analysis for the turbine stator blade for this temperature can be done with many cases in the Autodesk CFD.