Search Results (263)

Mass spectrometry (MS) and coupled gas chromatography-mass spectrometry (GC-MS) are globally recognized as the primary techniques for the analysis of gases or vapors due to their selectivity, sensitivity, accuracy, and reproducibility. When thermal stress is applied, vapors or gases are released as a result of the reactions and changes that occur. The analysis of these gases during the thermally induced reaction is scientifically referred to as evolved gas analysis (EGA), which is essential for confirming the occurrence of the induced reactions. Pyrolyzers, thermobalances, or simple heaters can increase the temperature of the analyzed samples according to a programmed and software-managed ramp, allowing for control over both the heating rate and isothermal stages. The atmosphere can also be varied to simulate pyrolysis or thermo-oxidative processes. This way, each induced reaction generates a unique evolved gas, which can be linked to a theoretically hypothesized mechanism. Mass spectrometry (MS) and coupled gas chromatography–mass spectrometry (GC-MS) are fundamental analytical methods used for on-line thermally induced evolved gas analysis (OLTI-EGA). Full article

Shifting towards electrified industrial energy systems is pivotal for meeting global decarbonization objectives, especially since process heat is a significant contributor to greenhouse gas emissions in the industrial sector. This review examines the changing role of heat exchanger networks (HENs) within electrified process industries, where electricity-driven technologies, including electric heaters, steam boilers, heat pumps, mechanical vapour recompression, and organic Rankine cycles, are increasingly supplanting traditional fossil-fuel-based utilities. The analysis identifies key challenges associated with multi-utility integration, multi-pinch configurations, and low-grade heat utilisation that influence HEN design, retrofitting, and optimisation efforts. A comparative evaluation of various methodological frameworks, including mathematical programming, insights-based methods, and hybrid approaches, is presented, highlighting their relevance to the specific constraints and opportunities of electrified systems. Case studies from the chemicals, food processing, and cement sectors demonstrate the practicality and advantages of employing electrified heat exchanger networks (HENs), particularly in terms of energy efficiency, emissions reduction, and enhanced operational flexibility. The review concludes that effective strategies for the design of HENs are crucial in industrial electrification, facilitating increases in efficiency, reductions in emissions, and improvements in economic feasibility, especially when they are integrated with renewable energy sources and advanced control systems. Future initiatives must focus on harmonising technical advances with system-level resilience and economic sustainability considerations. Full article

In high-pressure thermal power systems, corrosion-induced wall thinning in steam pipelines poses a significant threat to operational safety and efficiency. This study investigates the effects of gas–liquid two-phase flow on corrosion-induced wall thinning in pipe bends of high-pressure heaters in power plants, with particular emphasis on the mechanisms of void fraction and inner wall surface roughness. Research reveals that an increased void fraction significantly enhances flow turbulence and centrifugal effects, resulting in elevated pressure and Discrete Phase Model (DPM) concentration at the bend, thereby intensifying erosion phenomena. Simultaneously, the turbulence generated by bubble collapse at the bend promotes the accumulation and detachment of corrosion products, maintaining a cyclic process of erosion and corrosion that accelerates wall thinning. Furthermore, the increased surface roughness of the inner bend wall exacerbates the corrosion process. The rough surface alters local flow characteristics, leading to changes in pressure distribution and DPM concentration accumulation points, subsequently accelerating corrosion progression. Energy-Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) analyses reveal changes in the chemical composition and microstructural characteristics of corrosion products. The results indicate that the porous structure of oxide films fails to effectively protect against corrosive media, while bubble impact forces damage the oxide films, exposing fresh metal surfaces and further accelerating the corrosion process. Comprehensive analysis demonstrates that the interaction between void fraction and surface roughness significantly intensifies wall thinning, particularly under conditions of high void fraction and high roughness, where pressure and DPM concentration at the bend may reach extreme values, further increasing corrosion risk. Therefore, optimization of void fraction and surface roughness, along with the application of corrosion-resistant materials and surface treatment technologies, should be considered in pipeline design and operation to mitigate corrosion risks. Full article

The proposed study incorporates a stochastic demand side management (SDSM) strategy for a self-sufficient residential system powered from a PV source with a hybrid battery–hydrogen storage system to minimize the total degradation costs associated with key components, including Li-io batteries, fuel cells, and PEM electrolyzers. The uncertainty in demand forecasting is addressed through a scenario-based generation to enhance the robustness and accuracy of the proposed method. Then, stochastic optimization was employed to determine the optimal operating schedules for deferable appliances and optimal water heater (WH) settings. The optimization problem was solved using a genetic algorithm (GA), which efficiently explores the solution space to determine the optimal operating schedules and reduce degradation costs. The proposed SDSM technique is validated through MATLAB 2020 simulations, demonstrating its effectiveness in reducing component degradation costs, minimizing load shedding, and reducing excess energy generation while maintaining user comfort. The simulation results indicate that the proposed method achieved total degradation cost reductions of 16.66% and 42.6% for typical summer and winter days, respectively, in addition to a reduction of the levelized cost of energy (LCOE) by about 22.5% compared to the average performance of 10,000 random operation scenarios. Full article

This article examines the energy efficiency and climate impact of various heating methods commonly employed across industrial sectors. Fossil fuel combustion heat sources, which are predominantly employed for industrial heating, contribute significantly to atmospheric pollution and associated asset losses. The electrification of industrial heating has the potential to substantially reduce the total energy consumed in industrial heating processes and significantly mitigate the rate of global warming. Advances in electrical heating technologies are driven by enhanced energy conversion, compactness, and precision control capabilities, ensuring attractive financial payback periods for clean, energy-efficient equipment. These advancements stem from the use of improved performance materials, process optimization, and waste heat utilization practices, particularly at high temperatures. The technical challenges associated with large-scale, heavy-duty electric process heating are addressed through the novel innovations discussed in this article. Electrification and the corresponding energy efficiency improvements reduce the water consumed for industrial steam requirements. The article reviews new technologies that replace conventional process gas heaters and pressure boilers with efficient electric process gas heaters and instant steam generators, operating in the high kilowatt and megawatt power ranges with very high-temperature capabilities. Financial payback calculations for energy-optimized processes are illustrated with examples encompassing a range of comparative energy costs across various temperatures. The economics and implications of waste heat utilization are also examined in this article. Additionally, the role of futuristic, radical technical innovations is evaluated as a sustainable pathway that can significantly lower energy consumption without compromising performance objectives. The potential for a new paradigm of self-organization in processes and final usage objectives is briefly explored for sustainable innovations in thermal engineering and materials development. The policy implications and early adoption of large-scale, energy-efficient thermal electrification are discussed in the context of temperature segmentation for industrial-scale processes and climate-driven asset losses. Policy shifts towards incentivizing energy efficiency at the manufacturing level of heater use are recommended as a pathway for deep decarbonization. Full article

Oil shale, an unconventional oil and gas resource, can generate the required hydrocarbons through high-temperature pyrolysis. In situ conversion extraction technology utilizes downhole heaters to directly inject high-temperature heat into the oil shale layer to achieve the effect of oil and gas recovery. For the metal material components of the combustion heaters, the uneven temperature fields experienced during the start of operations, processing, and end of operations can lead to fatigue conditions, such as high-temperature creep, micro-damage, and micro-deformation due to thermal effects. To prevent the occurrence of the aforementioned issues, it is necessary to conduct fatigue life analysis of downhole combustion heaters. By combining actual combustion heater operation experiments with finite element simulation, this paper analyzes the impact of temperature, structure, and stress amplitude on the fatigue life of heaters. The results indicate that the fatigue life of the heaters is most significantly influenced by the metal gaskets, and the higher the exhaust gas temperature, the lower the fatigue life of the heater. Heating operations significantly reduce the fatigue life of the heater, while cooling operations have almost no effect on the fatigue life. Circular-pore metal gaskets have a higher fatigue life than those with a square hole shape. Considering only the thickness of the metal gaskets, the thicker the gasket, the higher the fatigue life. Stress amplitude has the most significant impact on the fatigue life of the heater; when the stress amplitude is doubled, the metal gaskets quickly undergo fatigue damage. Full article

This paper introduces a novel MEMS-based thermal flow sensor designed for high sensitivity and linearity across a wide range of gas flow velocities. The sensor incorporates a single microheater and two pairs of thermistors symmetrically arranged around the heater, with strategically placed obstacles to enhance performance. To ensure accuracy under varying flow conditions, the sensor is divided into two functional regions: one optimized for low flow velocities (0–1 m/s) and the other for high flow velocities (1–6 m/s). Simulations conducted using COMSOL Multiphysics reveal that including obstacles improves heat transfer and increases the interaction time between the heated surface and the flow, particularly in the high-flow region. In the low-flow regime, the sensor achieves a sensitivity of 2.5 SK/m with 91% linearity. In contrast, in the high-flow regime, the sensitivity increases to 6.5 SK/m with similarly high linearity. This dual-region design highlights the sensor’s versatility in handling a broad range of flow velocities, making it suitable for applications in medical, industrial, and environmental monitoring. These findings underscore the advantages of the dual-region design and obstacle integration, providing a robust solution for accurate flow measurement under diverse operating conditions. Full article

This paper presents a procedure for the energy optimization of domestic hot water (DHW) systems in hotels located in tropical climates that use centralized air conditioning systems. The study aims to maximize heat recovery from chillers and reduce the fuel consumption of auxiliary heaters by optimizing operational variables such as water mass flow in the primary and secondary DHW circuits and outlet temperature of the backup system. The optimization is implemented using genetic algorithms (GA), which enable the identification of the most efficient flow configurations under variable thermal demand conditions. The proposed methodology integrates a thermoenergetic model validated with real operational data and considers the dynamic behavior of hotel occupancy and water demand. The results show that the optimized strategy reduces auxiliary heating use by up to 75%, achieving annual energy savings of 8244 kWh, equivalent to 2.3 tons of fuel, and preventing the emission of 10.5 tons of CO₂. This study contributes to the design of sustainable energy systems in the hospitality sector and provides replicable strategies for similar climatic and operational contexts. Full article

This study examines the impact of Au nanoparticles (Au-NPs) on the chemoresistive gas sensing properties as a function of particle size. The sensing material is composed of ultrathin CuO/Cu₂O films, which are fabricated by either thermal deposition technology or spray pyrolysis. These are used on a silicon nitride (Si₃N₄) micro hotplate (µh) chip with Pt electrodes and heaters. The gas sensing material is then functionalised with Au-NP of varying sizes (12, 20, and 40 nm, checked by transmission electron microscopy) using drop coating technology. The finalised sensors are tested by measuring the electrical resistance against various target gases, including carbon monoxide (CO), carbon dioxide (CO₂), and a mixture of hydrocarbons (HC_Mix), in order to evaluate any cross-sensitivity issues. While the sensor response is markedly contingent on the structural surface, our findings indicate that the dimensions of the Au-NPs exert a discernible influence on the sensor’s behaviour in response to varying target gases. The 50 nm thermally evaporated CuO/Cu₂O layers exhibited the highest sensor response of 78% against 2000 ppm CO₂. In order to gain further insight into the surface of the sensors, a scanning electron microscope (SEM) was employed, and to gain information about the composition, Raman spectroscopy was also utilised. Full article

Increasing the efficiency and capacity of nuclear power units is a promising direction for the development of power generation systems. Unlike thermal power plants, nuclear power plants operate at relatively low temperatures of the steam working fluid. Due to this, the thermodynamic efficiency of such schemes remains relatively low today. The temperature of steam and the efficiency of nuclear power units can be increased by integrating external superheating of the working fluid into the schemes of steam turbine plants. This paper presents the results of a thermodynamic analysis of thermal schemes of NPPs integrated with hydrocarbon-fueled plants. Schemes with a remote combustion chamber, a boiler unit and a gas turbine plant are considered. It has been established that superheating fresh steam after the steam generator is an effective superheating solution due to the utilization of heat from the exhaust gases of the GTU using an afterburner. Furthermore, there is a partial replacement of high- and low-pressure heaters in the regeneration system, with gas heaters for condensate and steam superheating after the steam generator for water-cooled and liquid-metal reactor types. An increase in the net efficiency of the hybrid NPP is observed by 8.49 and 5.11%, respectively, while the net electric power increases by 93.3 and 76.7%. Full article

The residential sector is energy-consuming and one of the biggest contributors to climate change. In France, the adoption of photovoltaics (PV) in that sector is accelerating, which contributes to both increasing energy efficiency and reducing greenhouse gas (GHG) emissions, even though the technology faces several issues. One issue that slows down the adoption of the technology is the “duck curve” effect, which is defined as the daily variation of net load derived from a mismatch between power consumption and PV power generation periods. As a possible solution for addressing this issue, electric water heaters (EWHs) can be used in residential building as a means of storing the PV power generation surplus in the form of heat in a context where users’ comfort—the availability of domestic hot water (DHW)—has to be guaranteed. Thus, the present work deals with developing model-based predictive control (MPC) strategies—nonlinear/linear MPC (MPC/LMPC) strategies are proposed—to the management of EWHs in individual dwellings equipped with grid-connected PV systems. The aim behind developing such strategies is to improve both the PV power generation self-consumption rate and the economic gain, in comparison with rule-based (RB) control strategies. Inasmuch as DHW and power demand profiles are needed, data were collected from a panel of users, allowing the development of profiles based on a quantile regression (QR) approach. The simulation results (over 6 days) highlight that the MPC/LMPC strategies outperform the RB strategies, while guaranteeing users’ comfort (i.e., the availability of DHW). The MPC/LMPC strategies allow for a significant increase in both the economic gain (up to 2.70 EUR) and the PV power generation self-consumption rate (up to 14.30%ps), which in turn allows the ${\mathrm{CO}}_2$ emissions to be reduced (up to 3.92 $\mathrm{k}\mathrm{g}{\mathrm{CO}}_{2.\mathrm{eq}})$. In addition, these results clearly demonstrate the benefits of using EWHs to store the PV power generation surplus, in the context of producing DHW in residential buildings. Full article

Many cities are still struggling to comply with current air quality regulations. Road transport is usually a significant source of NOx emissions, especially in urban areas. Therefore, NOx from road vehicles needs to be further reduced below current standards to ultra-low or even zero-impact levels. In a novel, holistic powertrain design approach, this paper presents powertrain solutions to achieve zero-impact NOx emissions with an N1 class III diesel light commercial vehicle. The design is based on a compliance test matrix consisting of six real-world scenarios that are critical for emissions and air quality. As a design baseline, a vehicle concept meeting the emission requirements as set out in the European Commission’s 2022 Euro 7 regulation proposal is used. The baseline vehicle concept can achieve zero-impact NOx emissions in 67% of these scenarios. To achieve zero-impact NOx emissions in all scenarios, further advanced emission solutions are mandatory. In congested urban areas, the use of an exhaust gas aftertreatment system preheating device with at least 20 kW of power for 1 min is required. In high-traffic highway situations, an underfloor SCR unit with a minimum volume of 12 l or the restriction of the maximum vehicle speed at 130 km/h is required. Full article

Solar thermal energy is one of the most interesting sustainable solutions for decarbonizing the energy sector. Integrating solar collectors with other energy sources is common, as seen in domestic heating, where solar collectors are combined with common heaters to reduce fuel consumption (gasoline, electricity, gas, and biomass) and therefore, the energy cost. Similarly, this concept can be applied to nuclear energy, where the reduction in nuclear fuel consumption is very strategic for decreasing not only its cost but also the risk in handling, transportation, and storage (both the fuel and the nuclear waste as well). Nuclear energy, on the other hand, seems to be very useful in reducing the land occupation of concentrated solar power plants (CSPs) and helping a more constant production of electricity, both points being two important bottlenecks of CSP technologies. CSP and nuclear reactors, on the other hand, share common heating technologies and both can produce energy without CO₂ emissions. Solar and nuclear energy, especially with the advent of the fourth generation of small modular reactors (SMRs), present a compelling opportunity for sustainable electricity generation. In this work, we present a brief review of CSP technology, a brief review of SMR concepts and development, and a brief overview of the combination of these two technologies. The review shows that in general, combined SMR + CSP technologies offer several advantages in terms of a strong reduction in the solar field extension areas, improved dispatchability of energy, improved efficiency of the SMRs, and, in particular, lower nuclear fuel consumption (hence, e.g., with a lowered refueling frequency). Full article

Solar air heating systems offer an effective alternative for reducing greenhouse gas emissions at a profitable cost. This work details the design, construction, and experimental evaluation of a novel double-pass V-trough solar air heater with semicircular receivers, which was built with low-cost materials readily available in the Mexican market. Thermal performance tests were conducted in accordance with the ANSI-ASHRAE 93-2010 standard. The results indicated a peak collector efficiency of 0.4461 and total heat losses of 8.8793 W/(m² °C), with an air mass flow rate of 0.0174 kg/s. The instantaneous thermal efficiency varied between 0.2603 and 0.5633 with different air flow rates and an inlet air temperature close to the ambient temperature. The outlet air temperature reached 70 °C, making it suitable for dehydrating fruits or vegetables at competitive operating costs. Additionally, a second-law analysis was carried out, and the exergy efficiency was between 0.0037 and 0.0407. Finally, a Levelized Cost of Energy analysis was performed, and the result was USD 0.079/kWh, which was 31% lower than that of a conventional electric air heater system. Full article

As new energy-efficient technologies emerge, space and water heating systems are continuously evolving. The latest generation of heating, ventilation, and air conditioning (HVAC) systems in Canada and other countries is shifting away from natural gas heating to cleaner electrical options, such as air-source heat pump water heaters (ASHPWH). While many studies focus on reducing space heating, research on the effectiveness of ASHPWHs in cold climates is limited. This study aims to fill that knowledge gap by analyzing the performance of ASHPWHs in typical home applications across various climates in Canada. An experimental setup was constructed, and TRNSYS modeling was employed to evaluate the techno-economic and environmental performances of these systems in comparison to existing natural gas and conventional electric water heating systems. The findings of this research indicate that ASHPWHs possess the capability to substantially decrease greenhouse gas (GHG) emissions when compared to conventional natural gas-fired water heaters. Despite this significant environmental benefit, ASHPWHs may not be the most cost-effective option due to the prevailing natural gas pricing structure. Nevertheless, there is potential for these systems to become more economically viable in the future, particularly if an appropriate level of carbon pricing mechanisms is implemented. Full article