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Enhanced methods of energy conversion present a viable solution for addressing energy load challenges. This study introduces a vibrating combustion engine designed to enhance energy conversion efficiency by harnessing flexible dynamics and variable asymmetric motion. However, the consideration of its unique dynamic effects has emerged as a pivotal challenge in fuel-air mixing and combustion research. This study introduces a fuel spray and mixing simulation method that facilitates the reciprocal exchange of coupling parameters between the combustion and dynamics models. It iterates the simulation outcomes of motion and combustion to predict mixture formation. Subsequently, the method is employed to explore the impact of injection position on fuel spray and mixture formation. Results show that there is an optimum injection position for the operation frequency, and retarding or advancing leads to slow compression and weak gas motion for fuel spray and mixing, although retarded injection provides high in-cylinder gas pressure and temperature. The early injection generally causes long penetration, small droplet diameter, slight impingement, and fast evaporation, unless it is too early. The results further indicate that when IAP = 6 mm, a more uniform mixture can be attained at the beginning of combustion, leading to a thermal efficiency of up to 42.9% for the engine. [ABSTRACT FROM AUTHOR]

With their high storage capacity and energy efficiency as well as the compatibilities with renewable energy sources, high‐temperature aquifer thermal energy storage (HT‐ATES) systems are frequently the target today in the design of temporally and spatially balanced and continuous energy supply systems. The inherent density‐driven buoyancy flow is of greater importance with HT‐ATES, which may lead to a lower thermal recovery efficiency than conventional low‐temperature ATES. In this study, the governing equations for HT‐ATES considering buoyancy flow are nondimensionalized, and four key dimensionless parameters regarding thermal recovery efficiency are determined. Then, using numerical simulations, recovery efficiency for a sweep of the key dimensionless parameters for multiple cycles and storage volumes is examined. Ranges of the key dimensionless parameters for the three displacement regimes, that is, a buoyancy‐dominated regime, a conduction‐dominated regime, and a transition regime, are identified. In the buoyancy‐dominated regime, recovery efficiency is mainly correlated to the ratio between the Rayleigh number and the Peclet number. In the conduction‐dominated regime, recovery efficiency is mainly correlated to the product of a material‐related parameter and the Peclet number. Multivariable regression functions are provided to estimate recovery efficiency using the dimensionless parameters. The recovery efficiency estimated by the regression function shows good agreement with the simulation results. Additionally, well screen designs for optimizing recovery efficiency at various degrees of intensity of buoyancy flow are investigated. The findings of this study can be used for a quick assessment and characterization of the potential HT‐ATES systems based on the geological and operational parameters. Key Points: Four key dimensionless parameters for the high‐temperature aquifer thermal energy storage systems are identifiedThe displacement processes are classified into a buoyancy‐dominated regime, a conduction‐dominated regime, and a transition regimeMultivariable regression functions are demonstrated for the estimation of thermal recovery efficiency [ABSTRACT FROM AUTHOR]

The thermal recovery is facing the challenge of improving quality and efficiency. Steam-assisted gravity drainage (SAGD) steam circulation has a profound implications for the formal production. There is a lack of research on the situation when the steam injection pressure of injection well is lower than that of production well during startup stage. In this paper, the effects of diverse injection pressure difference on SAGD steam circulation and production stage are investigated by analytical modeling and numerical simulation, especially when the steam injection pressure of producer well is larger than that of injection well, and reliable results are obtained by temperature falloff test and model comparison validation. Meanwhile, in order to minimize the factors affecting the simulation accuracy, a sensitivity analysis of the temperature prediction model for the startup stage is carried out using Monte Carlo method and the finest possible mesh is used in the numerical simulation. The results show that:①The preheating results are faster and more uniform than the conventional preheating method when steam injection pressure of producer is greater than that of injector, and the subsequent production indexes are also superior to those of the conventional preheating method. ②The injected steam temperature had the greatest effect on the prediction accuracy of the analytical model; The finer the numerical simulation grid division, the lower the midpoint temperature of the horizontal well pair; ③An optimal range of injection pressure differences that achieves the best balance between preheating efficiency and thermal recovery effectiveness is achieved with Pprod-Pinj in the range of 400–500 kPa. ④The preheating method investigated in this paper minimizes the effect by unfavorable factors such as reservoir non-homogeneity, which holds the potential for more uniform, time-saving preheating and without the addition of field equipment. [ABSTRACT FROM AUTHOR]

It is necessary to take effective ways to reduce friction and wear grading of a friction pair for the purpose of improving the thermal efficiency and operating reliance of the internal combustion engine. As an effective way, coordinated multi-scaling structure optimization has gained more and more attention, however, its effect on coating adhesion strength remains unclear, and there is less systematic research on its interactive role in friction properties. The paper takes advantage of the stretching test and dynamic simulation calculation to study the influence of piston skirt waviness on coating adhesion as well as profile, waviness, and roughness on friction and wear performance. The research results show that coating adhesion strength will increase first and then decrease in the conditions of enlarging waviness depth, width, and roughness; in addition, surface roughness could generate a bigger effect on coating adhesion than waviness shape. Increasing the waviness width also reduces friction losses and wear in the piston skirt. When the waviness width increases from 0.25 mm to 0.40 mm, the friction losses of the piston skirt decrease by 27%, and the cumulative wear load on the skirt is reduced by 26%. However, under conditions of limited lubrication, smaller waviness widths are more effective in reducing wear. Additionally, increased roughness has a negative impact on the friction and wear characteristics of the piston skirt. This study provides valuable guidance for optimizing designs aimed at reducing friction and wear in internal combustion engine pistons and other mechanical components subject to friction and wear. [ABSTRACT FROM AUTHOR]

The organic Rankine cycle (ORC) is an effective way for engine waste heat recover (WHR). The selection of the working fluid is crucial. In recent years, low GWP and ODP working fluid have been invented. For R123, which is commonly used in engine ORC-WHR system, the alternative working fluid is R1233zd(E). In order to explore the performance of R123 and R1233zd(E) when applied to ORC-WHR system, this study conducted experimental studies of R123 and R1233zd(E) under a wide range of engine working conditions. The experiments were carried out under seven sets of engine working conditions with gradually increasing loads. Variable operating parameter experiments were carried out for R123 and R1233zd(E) at each engine load. The selected operating parameters include expander speed and superheat degree. The experimental results show that R123 has higher output power and thermal efficiency compared to R1233zd(E) at all engine conditions.The maximum output power and thermal efficiency of R123 are 1.55 kw and 5.81% respectively.The maximum output power and thermal efficiency of R1233zd(E) are 1.43 kw and 5.29% respectively. Taking the net output power as the evaluation index, the optimal expander speed of R123 is higher than that of R1233zd(E) under the same engine working condition, and the superheat degree has little effect on the net output power. [ABSTRACT FROM AUTHOR]

Methanol, as a carbon-neutral resource, exhibits significant potential in the automotive sector. The objectives of this study are to investigate the fuel economy, emission characteristics, and combustion properties of methanol in compression-ignition engines. The research findings indicated that the combustion duration of methanol significantly extended with increasing speed and load. In comparison to diesel, methanol exhibited a relatively lower peak heat release rate under various operating conditions. With an increase in injection pressure or an advancement in injection timing, the brake specific fuel consumption (BSFC) decreased initially and then increased. The optimal injection pressure for methanol was lower than that for diesel, while the optimal injection timing was advanced. As the EGR rate increased, BSFC gradually decreased at each speed. When comparing optimized methanol with diesel, the brake thermal efficiency (BTE) of methanol was 37.54%, slightly lower than that of diesel. Methanol's NOx, soot, and CO emissions were significantly lower than diesel, while methanol and formaldehyde emissions were higher, especially with a methanol emission of 0.83 g/kW.h. Overall, applying pure methanol as fuel in compression-ignition engines can significantly reduce emissions while maintaining the BTE as compared with that of diesel fuel, but the methanol emissions in the exhaust increase significantly. [ABSTRACT FROM AUTHOR]

Shortage of available freshwater has been becoming a critical issue, recently. For this matter, different types of solar still have been used to supply freshwater in rural places; however, their low performance is the main restriction. In this research, a stepped solar still is designed and built, and the steps are covered by wick porous material. This is a novel strategy for the stepped solar still. The distilled water productivity, the temperature of the internal space, first, middle and bottom steps as well as energy and exergy efficiencies are investigated experimentally. Experiments are carried out with porous material thicknesses of 4, 6, 8, and 12 mm and without porous materials in winter. Results indicate that the stepped solar still with a thicker porous medium has higher freshwater productivity and efficiency, and the temperature of internal space is affected by the presence of porous material as compared to no porous material. In addition, results show that the efficiency of stepped solar still with porous material thickness of 4, 8, 10, and 12 mm is 2.41%, 2.7%, 6.44% and 7.02% higher than the efficiency of the unmodified solar still, respectively. As a result, the porous material with a thickness of 12 mm is the optimal porous medium with productivity of one liter and thermal and exergy efficiencies of 24.71% and 3.528%. [ABSTRACT FROM AUTHOR]

Utilizing long-wavelength laser diodes (LDs) for pumping to achieve high-power fiber laser output is an effective method for attaining high quantum efficiency and excellent thermal management. In this work, we report on a Master Oscillator Power Amplifier (MOPA)-structured long-tapered Yb3+-doped fiber laser directly pumped by long-wavelength laser diodes. By shifting the center wavelength of the pump source to 1010 nm, the heat generation within the fiber laser is effectively controlled, thereby increasing the transverse mode instability (TMI) threshold. Additionally, the use of a long-tapered fiber enlarges the mode area and suppresses stimulated Raman scattering (SRS) effects that typically arise from increased fiber length. As a result, an output of 6030 W is achieved with an optical-to-optical (O–O) efficiency of 83.7%, a SRS suppression ratio exceeding 50 dB, and no occurrence of dynamic TMI. This approach provides a valuable reference for optimizing long-wavelength pumping to suppress nonlinear effects and also holds potential for wide-temperature operational applications. [ABSTRACT FROM AUTHOR]

Syngas produced from glycerol using aqueous phase reforming for nickel-based catalysts with different support materials were tested in a compression ignition (CI) engine. Experiments were conducted using nickel–alumina, nickel–lanthanum (NL), and nickel–ceria catalysts at 1:1, 1:2, 1:3, and 1:4 glycerol–water ratios and temperatures of 240°C, 260°C, and 280°C. The NL catalyst showed the highest syngas and hydrogen yield of 90.58% and 76.42%, respectively, at 1:3 ratio and 260°C. The optimized NL syngas and diesel were tested in a CI engine at 6 to 30 lpm flow rates. At 30 lpm flow, brake thermal efficiency increased by 3.15%, NOx emission was reduced by 21.22%, and smoke lowered significantly compared to diesel. The faster hydrogen combustion in syngas increased the heat release rate and cylinder peak pressure. CO and HC emissions increased at lower loads due to diluted combustion but reduced at higher loads. NL showed the best performance and emissions among the syngases due to higher hydrogen content. In summary, the NL syngas at 30 lpm showed great potential in CI engines by improving combustion and performance and reducing emissions. [ABSTRACT FROM AUTHOR]

The present work focuses on the impact of combustion phase shifting from CDC (conventional diesel combustion) to RCCI (reactivity controlled compression ignition) mode of operation under various premixed ratios of hydrogen on the combustion, performance and exhaust emissions of a partially modified CI (compression ignition) engine. The hydrogen premix ratios are varied from 10% to 60% with 10% increment and the engine is tested at 0.9 kW, 1.8 kW, and 2.7 kW. The experimental results have shown that the hydrogen participation up to 40% premixed ratio improves the homogeneousness and stability of the combustion, resulting in 8.19% increase in cylinder pressure and 27.81% increase in heat release rate (HRR) at 2.7 kW brake power. It is also observed that the premix phase of combustion is faster with up to 40% hydrogen participation as the 50% mass burn is found to shift towards TDC. At the same operating point, the combustion is also found to be more stable with 72% reduction in COVIMEP. The brake thermal efficiency (BTE) increases by 10.07% when operating at 2.7 kW brake power with a 40% premix ratio, compared to diesel CDC operation. The unburned hydrocarbon (UHC), carbon monoxide (CO), and PM emissions are reduced by 9.17%, 21.68%, and 9.51%, respectively, for the hydrogen premixed ratio of 40%, with a marginal increase in the oxide of nitrogen (NOX) emissions. [ABSTRACT FROM AUTHOR]

The combustion technology of hydrogen enriched natural gas can directly apply hydrogen energy to household gas, playing an important role in promoting the development of hydrogen energy. This study designed a domestic burner with porous media for hydrogen enriched natural gas. The effect of hydrogen blending ratio on the primary mix process in the injector was analyzed numerically, and an experiment was conducted to investigate the flame morphology, thermal efficiency and pollutant emissions of the hydrogen-enriched natural gas. The results show that there is a risk of backfire inside the injector when the hydrogen blending ratio exceeds 45%, and the pre-mixing uniformity decreases as the hydrogen doping ratio increases. Corresponding to variable hydrogen doping ratios, two combustion modes appear in the porous medium region, immerged combustion and surface combustion. When a combustion mode transition occurs, CO emissions increase rapidly, while thermal efficiency and NOx emissions show a downward trend. Additionally, the critical hydrogen doping ratio of mode transition drops as the porous density increases. Overall, taking the environmental characteristic and efficiency into considerations, the maximum hydrogen blending ratio should be not exceed 35%. [Display omitted] • A domestic burner with porous media for hydrogen enriched natural gas was designed. • The effect of hydrogen blending ratio on the primary mix process was analyzed. • The combustion performance and emissions of the domestic burner was investigated. • The transition of combustion mode induced by hydrogen doping ratio was observed. [ABSTRACT FROM AUTHOR]

The current energy and environmental problems demand the replacement of fossil fuels with renewable fuels. Research shows that hydrogen-enriched CNG fuels enhance the thermal efficiency of diesel engines while reducing gaseous emissions. This experimental work investigates the performance and emissions parameters of a diesel engine in dual fuel mode with hydrogen-enriched Bio-CNG (HBCNG). It is performed on a single-cylinder, four-stroke common rail direct injection (CRDI) diesel engine at 1500 rpm and 3.5 kW. The outcomes of this experiment are compared to a neat diesel operation. It is observed that at low load with 30% gaseous fuel substitution (GFS), brake thermal efficiency decreases by 13.70% and 15.53% for hydrogen and BCNG-enriched diesel, respectively. Similarly, at medium load, with the gaseous mixture of 40% H 2 and 60% BCNG co-combusted with 60% diesel, the BTE improves by 15.83%. At high load, 40% gaseous fuel mixture (40% H 2 + 60% BCNG) combustion with diesel results in 21.25% enhanced BTE. Moreover, at the same load condition and GFS, emissions of HC increase by 41.59%, CO decreases by 30%, CO 2 decreases by 55.36%, and NO x decreases by 25.94%. • The experiment is performed on a common rail direct injection diesel engine. • Hydrogen and Bio-CNG enriched diesel are used as the fuel. • Hydrogen and Bio-CNG mixture proportion in diesel are varied between 0 and 40%. • The engine load is varied between 0 and 80%. • The performance and emission parameters enhanced for 40% gaseous fuel mixture. [ABSTRACT FROM AUTHOR]

Ammonia, as a zero-carbon fuel, has the potential to serve as a medium for the production, transportation, and utilization of clean energy. The scaling up of green ammonia production also necessitates broader utilization channels for ammonia. Applying ammonia as a fuel in engines is an effective way to reduce carbon emissions. This paper employs dual direct injection technology of ammonia and diesel in a novel ammonia-fueled engine to implement various control strategies and investigates their effects on combustion and emission performance. The results indicate that when the ammonia injection timing is advanced from −40°CA ATDC to −60°CA ATDC, the flash boiling of liquid ammonia decreases the indicated thermal efficiency (ITE) below 39% and increases unburned gas emissions. Globally, injecting ammonia during the intake stroke could receive better performance. Split injection strategies of diesel significantly improve the ITE, especially under a higher pilot-injection ratio of 75%. Additionally, increasing the load benefits the ammonia combustion process. Raising the IMEP to 12 bar improves ammonia combustion efficiency to over 95%, with an ITE reaching 49%. [Display omitted] • Lifecycle zero carbon emission is achieved through green ammonia combustion. • Zero-carbon fuel ammonia is directly injected into a heavy-duty engine. • The influence of flashing boiling of ammonia in the cylinder is talked about. • Flexible control strategies are tested for lower unburned emissions and higher ITE. [ABSTRACT FROM AUTHOR]

This study examined the impact of varying concentrations of ammonia-borane (AB) in gasoline on engine performance and emissions across different load conditions. Four fuel formulations were tested: pure gasoline (G100) and gasoline blends containing 10%, 15%, and 20% AB (AB10, AB15, AB20). Increased AB concentration resulted in higher brake-specific fuel consumption (BSFC). While exhaust gas temperatures were highest with G100 (730.9 °C at full load), the AB blends, particularly AB20, exhibited lower temperatures, with a maximum reduction of 13.8%. The AB20 blend demonstrated elevated BSFC and increased oxygen (O₂) emissions but significantly reduced carbon monoxide (CO) emissions, with up to an 88.2% decrease at full load. Nitrogen oxide (NO x) emissions were generally lower for all AB blends. The highest NO x value was measured with G100 fuel at full load, while the lowest NO x value was measured with AB10 fuel. Under these conditions, a 23% decrease in NO x value was observed with AB10 fuel compared to G100. The engine's thermal efficiency decreased with AB blends at all load levels compared to pure gasoline. Thermal efficiency decrease of 13.76%, 22.32%, and 30.88% occurred for AB10, AB15 and AB20, respectively compared to G100.Overall, incorporating AB in gasoline reduced thermal efficiency and led to a notable decrease in NO x , hydrocarbons (HC), and CO emissions. [Display omitted] • Alcohol-gasoline blend fuels AB10, AB15 and AB20 were created. • All blended fuels were tested in a single cylinder gasoline engine. • AB blends show higher brake specific fuel consumption (BSFC) values compared to pure gasoline. • AB10, AB15 and AB20 showed lower thermal efficiency compared to G100 at all engine loads. • AB blends reduced harmful emissions such as CO, HC and NOx. [ABSTRACT FROM AUTHOR]

The vehicle sector has seen an upsurge in energy demand due to population expansion. Due to the escalating costs and exhaustion of fossil fuels, researchers are now dedicating more of their endeavors to exploring other options. The objective of this investigation, which is being conducted on a single-cylinder DI diesel engine propelled by hydrogen and diesel, is to optimize engine load. We evaluated the investigation on hydrogen/diesel composites against unadulterated diesel (D100). Different variations of fuels with varying percentages of hydrogen supplementation, viz., DH5 (diesel and 5% hydrogen), DH10 (diesel and 10% hydrogen), and DH15 (diesel and 15% hydrogen), were analyzed. In the experimental investigation, we used an injection pressure of more than 220 bar at 18:1 compression ratio for load optimization, and we used a single fuel injector with a diameter of 0.25 mm, The results showd improved brake thermal efficiency of 1.8% for DH5, 5.2% for DH10, and 17.6% for DH15, along with a drop in fuel consumption of 1.7% for DH5, 14.5% for DH10, and 31.6% for DH15. In addition, the addition of hydrogen to diesel demonstrates a promising reduction in smoke emissions of 10.5%, carbon monoxide (CO), and hydrocarbon (HC) emissions by DH15 under full load conditions. The results were subjected to regression analysis using an artificial intelligence network (ANN), to enhance the performance and reduce emissions of fuel mixtures. The ANN proves to be a very good method for the regression of data and prediction. The ANN provides an excellent fit for all the parameters, with a fitting value of more than 99%. [Display omitted] • Diesel-H2 mixes outperformed pure diesel fuel in terms of BTE. • Blends of diesel with H2 lowered BSFC and smoke emissions. • NOx emissions are increased by diesel-H2 mixes. • The engines performance and emission characteristics were predicted using ANN. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative design for an "inorganic salt-expanded graphite" composite thermochemical system. The storage unit is made of a perforated, compressed, expanded graphite block impregnated with molten CaCl2∙6H2O; the humid air passes through the holes that allow the moisture to diffuse and react with the salt. The prepared block underwent 90 hydration-dehydration cycles. Although most of the performed cycles were carried out with salt overhydration and deliquescence, the treated samples have remained mechanically and thermally stable with no drop in energy density. The volumetric energy density of the composite ranged from 135.5 to 277.6 kWh/m3, depending on airflow rate and absolute humidity. To ensure composite material cycling stability, the energy density of the block was measured during hydration at similar conditions of absolute humidity, inlet temperature, and airflow rate (0.01 kgwater/kgair, 20 °C, 400 l/min). The average energy density at these conditions was sustained at 219 kWh/m3. The block integrity was monitored by visual inspection after removing it from the reactor chamber every few cycles. Both the composite material and its manufacturing process are simple and easy to scale up for future commercialization. [ABSTRACT FROM AUTHOR]

This paper presents an analysis and optimization of a polygeneration power-production system that integrates a concentrating solar tower, a supercritical CO2 Brayton cycle, a double-flash geothermal Rankine cycle, and an internal combustion engine. The concentrating solar tower is analyzed under the weather conditions of the Mexicali Valley, Mexico, optimizing the incident radiation on the receiver and its size, the tower height, and the number of heliostats and their distribution. The integrated polygeneration system is studied by first and second law analyses, and its optimization is also developed. Results show that the optimal parameters for the solar field are a solar flux of 549.2 kW/m2, a height tower of 73.71 m, an external receiver of 1.86 m height with a 6.91 m diameter, and a total of 1116 heliostats of 6 m × 6 m. For the integrated polygeneration system, the optimal values of the variables considered are 1437 kPa and 351.2 kPa for the separation pressures of both flash chambers, 753 °C for the gasification temperature, 741.1 °C for the inlet temperature to the turbine, 2.5 and 1.503 for the turbine pressure ratios, 0.5964 for the air–biomass equivalence ratio, and 0.5881 for the CO2 mass flow splitting fraction. Finally, for the optimal system, the thermal efficiency is 38.8%, and the exergetic efficiency is 30.9%. [ABSTRACT FROM AUTHOR]

The present work proposes the application of CH 4 and H 2 synergy to improve the performance of the Wankel rotary engine (WRE). The whole work was experimentally conducted at 1500 r/min. The results indicate that CH 4 WRE can achieve similar power and significantly higher thermal efficiency than gasoline WRE based on quantitative control, with a maximum absolute efficiency improvement of 11.4%. At the same time, it also can achieve 64% and 77% maximum reduction of CO and NO emissions, respectively. CH 4 –H 2 synergy can further improve the performance of CH 4 -fueled WRE, which can broaden the lean flammability limits and make qualitative control application possible. Compared with CH 4 WRE with quantitative control, qualitative control hybrid fuel WRE can achieve a maximum relative improvement of 6.54% in brake thermal efficiency and significantly reduced NO and CO emissions. However, the extent of qualitative control is limited by cyclic variation. Overall, CH 4 –H 2 synergy can be a potential alternative to elevate the performance of WRE, the key to which is the reasonable match of synergy level and qualitative control extent. • Comparison of performances between CH4 and gasoline Wankel rotary engines. • CH4 has significant advantages in efficiency, CO and NO emission than gasoline. • CH4–H2 synergy can further improve the performance of the CH4 Wankel rotary engine. • Blending H2 coupling qualitative control is a good load control model in CH4 WRE. [ABSTRACT FROM AUTHOR]

The hydrogen internal combustion engine (H 2 -ICE) is proposed as a robust and viable solution to decarbonise the heavy-duty on- and off-road, as well as the light-duty automotive, sectors of the transportation markets and is therefore the subject of rapidly growing research interest. With the potential for engine performance improvement by controlling the internal mixture formation and avoiding combustion anomalies, hydrogen direct injection (H 2 DI) is a promising combustion mode. Furthermore, the H 2 -ICE poses an attractive proposition for original equipment manufacturers (OEMs) and their suppliers since the fundamental base engine design, components, and manufacturing processes are largely unchanged. Nevertheless, to deliver the highest thermal efficiency and zero-harm levels of tailpipe emissions, moderate adaptations are needed to the engine control, air path, fuel injection, and ignition systems. Therefore, in this article, critical design features, fuel-air mixing, combustion regimes, and exhaust after-treatment systems (EATS) for H 2 DI engines are carefully assessed. [Display omitted] • Key design aspects for achieving high efficiency and low emissions summarised. • Injection and intake ports are critical for good in-cylinder mixture formation. • Thermal management is required to mitigate abnormal combustion. • Advanced boosting system required to obtain high power density. [ABSTRACT FROM AUTHOR]

The effect of cyclization degree of nitrogen thermal pretreatment on the radial structure difference of polyacrylonitrile(PAN) oxide fibers is explored. In this paper, PAN fibers were isothermally heated in nitrogen at 170°C, 190°C and 210°C for 0, 10, 20, 30, 40, and 50 min, respectively, so as to obtain pre‐treated fibers with cyclization degrees of 0%, 19.96%, 35.18%, 38.92%, 42.80%, and 53.12%, respectively. The pre‐treated fibers were further stabilized in an oxygen atmosphere. The scanning results show that the radial structure difference of oxide fibers first decreases and then increases with cyclization degree increasing. Through FTIR, SEM and Raman characterization, it is found that this phenomenon is mainly related to the influence of nitrogen thermal pretreatment on oxygen diffusion. Therefore, to improve the thermal stability efficiency of PAN fibers by means of nitrogen thermal pre‐treatment, it is necessary to control the degree of cyclisation, and the appropriate degree of cyclisation in the present work is about 35%. [ABSTRACT FROM AUTHOR]

Solar desalination has a significant potential for addressing the increasing water scarcity of the world. Solar stills offer a sustainable solution for desalination of brackish water. Integration of Phase Change Material (PCM) in the still is one of the options for enhancing its productivity. Integration of PCM in solar stills has gained attention due to its capability to efficiently store and release thermal energy thereby enhancing its productivity. The present work proposes a modeling framework for the performance assessment of simple double slope solar stills integrated with PCM. The methodology is based on energy and exergy balance of the overall system. The exergy destruction associated with the still has been evaluated for the basic still and is compared with the case of PCM integrated still. The developed mathematical modeling framework is validated based on comparisons with the experimental observations for the south Indian location of Kozhikode. Lauric acid is considered as the representative PCM due to its favorable thermal properties for the application in solar stills. There is a reasonable agreement between the theoretical and experimental observations. With the incorporation of lauric acid as the PCM in the system, daily yield, daily thermal efficiency and exergy efficiency were found to be increased by 8.9%, 10.6%, and 3% respectively. A generic modelling framework for energy and exergy-based performance assessment of a PCM integrated still has been presented, which will be a useful tool for system optimization. Integration of different PCM with enhanced thermal properties are planned as future work for overall system optimisation for maximum energy efficiency. [ABSTRACT FROM AUTHOR]

Drying is a crucial step in cocoa production, for storing and reducing grain humidity. In Colombia, particularly in the Antioquia region, solar energy is used in simple structures called marquesinas. In this work, the authors characterized the process energetically by determining its specific energy consumption (SEC, 27793.9kJ/kg), the thermal efficiency of the system (ν, 12.94%), and specific cocoa drying process cost: 2.27 USD$/kgdry,cocoa (aprox.10442COP$/kgcacaposseco). At the end, with this information, is constructed grain mass loss curve versus time. The drying on the first day was faster than the following days. The main disadvantage of the greenhouse was that the beans gained moisture at night. For this reason, extra energy and time were necessary to remove the additional humidity acquired by the air condensing over the cocoa beans. This phenomenon decreased the thermal efficiency of the processes and increased its drying time. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to examine the environmental effects of plastic waste on the atmosphere and its implications for disaster waste management. It focuses on using ammonia, pyrolyzed plastic oil and the effectiveness of alumina nanoparticles as a catalyst. Design/methodology/approach: The research explores different combinations of conventional diesel and nano Al2O3 derived from pyrolyzed plastic oil (ranging from P10 to P40). Critical performance metrics evaluated include brake mean effective pressure (BMEP), brake specific fuel consumption, brake thermal efficiency and emissions of CO2, CO and NOx. The study specifically investigates the impact of adding 50 ppm of Al2O3 nanoparticles to these blends. Findings: The findings indicate that using blended fuels with nanoadditives significantly lowers pollution. Specifically, the P30 blend with 50 ppm of Al2O3 nanoparticles greatly reduced CO emissions. Additionally, the same blend reduced NOx emissions and CO2 emissions. The P30 mix showed improved BMEP and brake thermal efficiency due to its density, calorific value and viscosity (6.3 bar). The P30 blend exhibited higher thermal efficiency due to decreased heat loss, whereas conventional diesel demonstrated the best mechanical efficiency due to its longer ignition delay. Originality/value: This study highlights the potential of using Al2O3 nanoparticles and pyrolyzed plastic oil to reduce emissions and enhance the performance of internal combustion engines. It underscores the environmental benefits and implications for disaster waste management by converting plastic waste into useful resources and reducing air pollution. [ABSTRACT FROM AUTHOR]

Aim: Understanding the ecological determinants of interspecific achromatic (light‐to‐dark) plumage variation in birds is crucial yet challenging due to the complex interplay of climatic, habitat‐related, and morphological influences. This study aimed to disentangle the effects of temperature, precipitation, habitat openness, body mass and hand‐wing index (HWI, a widely used single‐parameter proxy for the extent to which a species relies on flight) on shaping achromatic plumage variation among bird species. Location: Global. Time Period: Contemporary. Major Taxa Studied: Birds. Methods: Based on data from over 8000 sessile bird species globally, we employed phylogenetic linear regressions to account for achromatic plumage colour in relation to temperature, precipitation, habitat openness, body mass and HWI, while correcting for phylogenetic non‐independence between species. Furthermore, we conducted phylogenetic path analyses to decompose direct from indirect effects. Results: We found that temperature, precipitation, habitat openness and body mass exerted separate but interactive effects on the variation in achromatic colour across species. Species inhabiting cold, wet or densely vegetated environments were darker coloured, while smaller species were lighter. Darker plumage was more strongly related to higher precipitation in colder regions for nocturnal species. For diurnal species, darker plumage was more closely associated with higher precipitation in more open habitats, whereas lighter plumage was more linked to lower mass in denser habitats. Noteworthy was the identification of a substantial correlation between achromatic colour and HWI. Diurnal species that are more aerial were lighter. Conversely, nocturnal flyers, especially females, tended to be darker. Main Conclusions: The findings highlight the multifaceted nature of plumage coloration evolution, with adaptations for thermal efficiency, crypsis, signalling, waterproofing or protection against bacteria. However, the variable relative importance of these factors among groups emphasizes the significance of each factor in different contexts. [ABSTRACT FROM AUTHOR]

Heat transfer enhancement is showing a relatively positive effect on compact heat exchanger performance in automobile applications. Heat transfer enhancement helps to increase the thermal efficiency of the heat exchanger, allowing it to transfer more heat in less time. This helps to reduce the fuel consumption of the vehicle and increase its efficiency. Present researches focus on the enhancement of high-performance heat exchangers in heavy cargo vehicles in the automobile sector. Compact heat exchangers having low space occupancy and high performance coolant blends need to be studied for heat transfer applications. The work is a case study of blends comparison with and without Nano addition to check the variation after adding 1% Al2O3 to locally available coolants like TFC Anti-freeze coolant, MFC, Castrol. The experiments were run at 60℃ and 80℃ and 1.765, 3.53 bar pressure taken as full flow and pressure drop conditions. The Sonication process was also explained to evaluate the thermal properties of coolant blends before and after NANO-addition. The addition of NANO-Al2O3 with MFC gave good results when compared with the others. [ABSTRACT FROM AUTHOR]

This paper presents a computational analysis of the thermoelectric efficiency of hybrid solar chimneys equipped with ventilated photovoltaic (PV) panels with multiple fresh air inlets. The problem addressed is the overheating of the photovoltaic cells, which reduces their electrical efficiency. The influence of multiple air inlets on the electrical and thermal performance of PV/T collectors is the focus of this study. The main objective is to reduce the overheating of the photovoltaic cells and improve their efficiency. This is achieved by using multiple passive ventilation sources instead of placing ventilation systems behind the photovoltaic panels to extract heat and distribute warm air. The implicit finite difference approach is used to discretize the governing heat and mass transfer equations, which are then solved using the Thomas algorithm and the iterative Gauss-Seidel method. The results are obtained by adjusting several important factors, including Raleigh and Reynolds numbers and chimney geometric aspects. The results show that the simultaneous addition of several fresh air openings improves the thermal efficiency by 68% and the electrical efficiency by 5% compared to a chimney with a single vertical duct. The study concludes that this system offers an effective solution for improving the performance of photovoltaic panels, thus contributing to clean energy production. [ABSTRACT FROM AUTHOR]

In the study, the focus was on evaluating the second law efficiency of a heat exchanger tube operating under continuous heat flux and turbulent flow conditions. The evaluation involved the use of a hybrid GnP and Fe3O4 and modified coiled wire as passive heat transfer enhancement techniques. The primary objective was to investigate the impact of these combined techniques on thermal and hydraulic performance, entropy generation number, Bejan number and second law efficiency. To achieve this, different mass fractions of GnP and Fe3O4 nanoparticles were used in the hybrid nanofluid, along with two forms of modified coiled wire: barrel type and hourglass type. The experimental results indicated that the utilization of hybrid nanofluids and modified helical inserts led to a noticeable improvement in the second law efficiency of the heat exchanger tube. However, it was observed that the differences in entropy generation number and Bejan number between the barrel and hourglass types were not significant, mainly due to higher frictional losses associated with the latter. The highest recorded second law efficiency was 0.416, while the lowest entropy generation number was 0.118. These values were achieved through the combined use of GnP and Fe3O4 with a mass fraction of 0.4% and a barrel-type coiled wire insert with a pitch ratio of 0.5. [ABSTRACT FROM AUTHOR]

Hybrid oils ensure multifaceted technological (self‐lubricating and favorable fatty acid properties), and sustainable (environmental, economic, and societal) benefits towards biodiesel conversions. The hybrid oils (Hydnocarpus wightiana oil and waste cooking oils [40:60 v/v]) were synthesized to methyl ester with alkaline catalyst sodium hydroxide through the base‐transesterification process. The resulting hybrid oil methyl ester (HOME) is 96.68%. The crude oil (CO) and its HOME underwent characterization using gas chromatography–mass spectrometry, Fourier transform infrared spectroscopy, and hydrogen‐1 nuclear magnetic resonance spectroscopy. The physicochemical properties of crude oils and hybrid biodiesel were analyzed and compared to pure diesel. Different blends of biodiesel–diesel, including binary (20% HOME + 80% diesel [D]), ternary (60% D + 20% HOME + 20% heptanol [H]), and quaternary (20% HOME + 20% H + 10% CO + 50% D) blends, were tested in a single‐cylinder compression ignition (CI) engine under various load conditions to assess their performance, emissions, and combustion properties. Experimental findings indicate that the addition of heptanol to diesel or hybrid biodiesel (ternary blend) enhances brake thermal efficiency, reduces brake‐specific fuel consumption, and leads to longer ignition delays, resulting in higher internal combustion pressure and thermal energy release rates compared to the quaternary blend. Additionally, compared to pure diesel, the ternary blend exhibits decreased emissions of carbon monoxide (CO) and hydrocarbon (HC), with a slight increase in nitrous oxide (NOx) and carbon dioxide (CO2). Notably, the ternary blend emerges as a distinct alternative biodiesel blend suitable for direct use in CI engines without requiring any engine modifications. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are considered as promising next‐generation light sources for optoelectronic and biomedical applications. Nevertheless, NIR phosphors with large bandwidths, long emission peaks, high external quantum efficiencies (EQEs) and valuable thermal stabilities are challenging to develop. Herein, this study reports a novel gallium germanate host, Ga3Al3Ge2O13 (GAGO), with a large bandgap and rigid host lattice for Cr3+ ion doping. The blue LED excitable GAGO:0.012Cr3+ phosphor can produce broadband NIR emission with a maximum intensity at 816 nm and a full‐width at half‐maximum (FWHM) of 187 nm. Notably, the phosphor also exhibits an excellent EQE of 35.8% and perfect thermal stability (I423 K/I298 K = 67.4%). Moreover, an attractive NIR afterglow duration of more than 24 h is achieved in the GAGO:0.004Cr3+ phosphor. The type and origin of the traps are discussed, and a possible long persistent luminescent (LPL) mechanism is proposed. Finally, an NIR pc‐LED based on a GAGO:0.012Cr3+ phosphor is fabricated. The results demonstrate that the obtained phosphors show great potential for use in night vision, nondestructive detection, bioimaging and information encryption. This study provides new insight into the development of broadband NIR luminescent materials with high efficiency, good thermal stability and extraordinary afterglow performance. [ABSTRACT FROM AUTHOR]

A photovoltaic thermal panel (PV/T) is an integrated module that harnesses both photovoltaic and solar thermal technologies to convert solar energy into electricity and heat, thereby enhancing overall energy efficiency. This paper aims to explore the suitability of PV/T solar heat pump systems across various climate zones and assess their potential for widespread application. By analyzing the operating principles of an indirect expansion PV/T solar heat pump system in conjunction with the climate characteristics of different regions, MATLAB R2019b/Simulink software was employed to evaluate the photoelectric performance of PV and PV/T systems in representative cities across five distinct climate zones in China during typical winter days. Key metrics, such as power generation, hot water storage tank temperature, indoor temperature, and system COP, were chosen to assess the heating performance of the PV/T solar heat pump system. The findings indicate that the winter ambient temperature significantly affects the photoelectric efficiency of both the PV and PV/T systems. While higher latitudes with lower ambient temperatures yield greater photoelectric efficiency, the southern regions exhibit higher power generation during winter. The winter heating effectiveness of the PV/T solar heat pump system is mainly influenced by indoor and water tank temperatures, with Harbin's system performing the poorest and failing to meet heating demands, whereas Nanjing's system shows the best results. [ABSTRACT FROM AUTHOR]

Cogeneration is widely recognized as one of the most efficient methods of electricity generation, with gas turbine-based systems playing a critical role in ensuring reliability, sustainability, and consistent power output. This paper presents an energy efficiency analysis of a 14 MW high-efficiency cogeneration unit, featuring a modernized gas turbine as its core component. Since gas turbines often operate under varying loads due to fluctuating demand, this study examines their performance at 100%, 75%, and 50% load levels. It is observed that the efficiency of the gas turbine declines as the load decreases, primarily due to losses resulting from deviations from the design flow conditions. A detailed energy balance, Sankey diagram, and a comparative analysis of performance metrics against the manufacturer's guarantees are provided for each load scenario. The results indicate that net thermal efficiency decreases by 10.7% at 75% load and by 30.6% at 50% load compared to nominal performance at full load. The performance at full load closely aligns with the values guaranteed by the gas turbine supplier. The gross electrical power output is 1.33% higher than the guaranteed value, and the thermodynamic circuit's efficiency is 0.49% higher under real conditions. This study represents the initial phase of transitioning the turbine to operate on a fuel blend of natural gas and up to 20% hydrogen, with the goal of reducing CO2 emissions. As a novel contribution, this paper provides a systematized method for calculating and monitoring the in-service performance of gas turbines. The mathematical model is implemented using the Mathcad Prime 8.0 software, which proves to be beneficial for both operators and researchers. [ABSTRACT FROM AUTHOR]

This study focuses on the great challenges for combined cooling and power supply on hypersonic aircrafts. To address the issues of low thermal efficiency and high fuel consumption of heat sink by the existing CO2 supercritical Brayton cycle, a novel fuel-based CO2 transcritical cooling and power (FCTCP) system is constructed. A steady-state simulation model is built to investigate the impacts of combustion chamber wall temperatures and fuel mass flow rates on the FCTCP system. Thermal efficiency of the CO2 transcritical cycle reaches 25.2~32.8% under various combustion chamber wall outlet temperatures and endothermic pressures. Compared with the supercritical Brayton cycle, the thermal efficiency of novel system increases by 54.5~80.9%. It is found from deep insights into the thermodynamic results that the average heat transfer temperature difference between CO2 and fuel is effectively reduced from 153.4 K to 16 K by split cooling of the fuel in the FCTCP system, which greatly enhances the matching of CO2–fuel heat exchange temperatures and reduces the heat exchange loss of the system. Thermodynamic results also show that, in comparison to the supercritical Brayton cycle, the cooling capacity and power generation per unit mass flow rate of working fluid in the FCTCP system increased by 75.4~80.8% and 12.9~51.6%, respectively. The FCTCP system exhibits a substantial performance improvement, significantly enhancing the key characteristic index of the combined cooling and power supply system. This study presents a novel approach to solving the challenges of cooling and power supply in hypersonic aircrafts under limited fuel heat sink conditions, laying the groundwork for further exploration of thermal management technologies of hypersonic aircrafts. [ABSTRACT FROM AUTHOR]

Biofuel made from Syzygium cumini, often known as Jamun, has the potential to be a low-cost, sustainable, and emission-free alternative. In this work, we experimentally explore the performance of a compression ignition (CI) engine that burns a blend of hydrogen and biodiesel. Hydrogen is pumped into the air intake manifold by means of a hydrogen gaseous supplement that, when exposed to atmospheric conditions, co-combusts with a pilot flame ignited by Jamun oil. To investigate the impact of hydrogen supplementation on performance and exhaust emission, a variety of hydrogen–Jamun fuel mixture proportions are provided to the engine. The research demonstrates that adding hydrogen improves the thermal efficiency (5%) of diesel engines whereas lowering specific energy fuel consumption (4%) at fixed Jamun flow rates. The gas emission data demonstrates that when hydrogen (HC) emission (12%) supplements decreases, NOx emission (10%) increases somewhat but opacity (8%) increases significantly. The experiment demonstrates that hydrogen and Jamun duel fuel in compression ignition engines burn smoothly. [ABSTRACT FROM AUTHOR]

The effects of compression ratio and injection timing on a direct injection spark ignition hydrogen engine under various excessive air ratios were analyzed using a 0.4-L single-cylinder engine in this study. The engine speed was set to 1500 rpm, and the excessive air ratio was changed by controlling the amount of injected hydrogen under wide-open throttle conditions. The compression ratio was changed from 10, 12, and 14 and the injection timing was varied from BTDC 200, 160, 120°CA. The results revealed that for a compression ratio 14 at a rich limit, late injection timing reduced knocking incidence by taking advantage of stratified mixtures combustion and increased indicated thermal efficiency by reducing combustion loss while producing lower NOx emissions. For compression ratio 14 at an excessive air ratio of 2.2, late injection timing increased indicated thermal efficiency by reducing both combustion and heat losses, achieving the higher indicated thermal efficiency of 42.3%. Although NOx emissions increased with the injection timing retardation, NOx emissions decreased to under 1 g/kWh under excessive air ratios above 2.5 conditions at all injection timings. [ABSTRACT FROM AUTHOR]

With the tightening of emission regulations for marine engines, it has become increasingly important to explore efficient and clean combustion strategies in diesel–natural gas dual–fuel marine engines. This study, for the first time, compared and analyzed the effects of single and split injection strategies on the combustion process in a marine medium-speed dual-fuel engine with a natural gas substitution rate of 93.3%. Optimal strategies were compared for single injection [Case A: start of injection (SOI)=−15° crank angle (CA) after top dead center (ATDC)] and split injection (Case B: SOI1=−60°CA ATDC, SOI2=−10°CA ATDC). The analysis of Cases A and B revealed that employing a split pilot diesel injection strategy enhances engine thermal efficiency—Case B had a 0.77% increase in efficiency compared with Case A. More importantly, the split injection strategy proved to be more effective in reducing emissions; compared with Case A, Case B had a 36.3% and 49.4% decrease in NOx and CH4 emissions, respectively. A deeper examination of the combustion process in Case B revealed that the reactivity in specific cylinder regions was enhanced, thereby increasing the flame propagation speed in those areas. Moreover, the strategy reduced the proportion of pilot diesel diffusion combustion, leading to lower high temperatures and aiding in the reduction of NOx formation. These findings provide a technological reference for improving energy conversion efficiency and facilitating cleaner combustion in future applications of low-carbon fuels in dual-fuel marine engines. [ABSTRACT FROM AUTHOR]

Improving the quality of fuel represents an effective solution to address the long-standing issue of engine emissions. This study adopts CeO2 and carbon nanotubes as additives, which are blended with neat diesel using a physicochemical method to produce nanofuel. The research investigated the combustion and emission performance of a high-pressure common rail four-cylinder engine under various operating conditions, utilizing different types of nanomaterials, nanoparticle sizes, and biofuel substitutes as variables. The outcomes of the study indicate superior performance of the nanofuel compared with neat diesel across all evaluated aspects. Notably, the size of the added particles directly influenced the beneficial enhancements achieved in diesel fuel. Additionally, the nanofuel containing carbon nanotubes demonstrated a greater improvement effect than the one incorporating CeO2. Furthermore, when compared with neat diesel, the combustion of carbon nanotubes (CNT) nanofuel at 100% load resulted in a notable 4.0% increase in brake thermal efficiency, coupled with reductions of 3.0% in brake specific fuel consumption and 8.8%, 4.4%, 4.9%, and 9.6% reductions, respectively, for carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and smoke emissions. It is noteworthy that the incorporation of biofuel alternatives, such as biodiesel and ethanol, into nanofuels exhibited even further enhanced effects in terms of promoting combustion and reducing emissions. The findings of this study serve as an important reference for selecting suitable nanofuels tailored to meet diverse operational demands of engines. [ABSTRACT FROM AUTHOR]

Compared with Earth, the lunar surface's environment is more complex, which suggests that the nuclear energy Helium–Xenon closed Brayton cycle (NHCBC), supplying electricity to the lunar base, may operate under off-design conditions. A thermodynamic model coupled with the lunar surface environment is established in this paper to analyze the effects of lunar environment exposure, including solar radiation exposure, lunar dust toxicity, and meteorite impact, on a given NHCBC. The results show that the output capacity of a given NHCBC is suppressed during the daytime and enhanced during the nighttime. The lunar dust will improve the system's output capacity at night but will also significantly inhibit the output capacity of the cycle during the daytime, resulting in a fluctuation of 824 % of the system without lunar dust. The output fluctuation of NHCBC is reduced after meteorite impact, while the output capacity of the NHCBC is suppressed, destroyed even worse. The optimization of cycle parameters can alleviate the influence of the lunar environment exposure on NHCBC to a minimal extent. This paper aims to analyze the impact of lunar surface environment exposure on the cycle parameters and output work characteristics of NHCBC and to provide some guidance for the subsequent application of nuclear energy in the lunar base. • A mathematical model of a nuclear energy cycle for a lunar base was established. • Lunar surface environment threats pose economic and safety risks to the energy cycle. • Optimizing a single-cycle parameter is unlikely to enhance energy cycle robustness. • Reducing radiator area to enhance cycle robustness sacrifices thermal efficiency. [ABSTRACT FROM AUTHOR]

This article presents the production and performance analysis of biodiesel from a blended oil comprising 20% soybean oil and 80% rice bran oil. The production process utilizes transesterification with methanol and NaOH, and the biodiesel synthesis time is optimized using a homogenizer. The biodiesel is tested on a four-stroke single-cylinder internal combustion (IC) engine, where key parameters such as brake thermal efficiency and specific fuel consumption are measured. The study compares the performance of biodiesel derived from the blended oil with biodiesel produced from pure soybean oil. Experimental results reveal that the biodiesel from the blended oil offers higher efficiency. Specifically, the brake thermal efficiency of the blended biodiesel increases with load, achieving values of 7.4%, 14.3%, 21.9%, and 23.6% at loads of 1kg, 2kg, 3kg, and 4kg, respectively. In terms of brake-specific fuel consumption, the blended biodiesel showed values of 2.425, 1.536, 1.168, and 0.989 kg/kW-hr for the same loads. The time required to consume 5 ml of blended biodiesel at a constant 1500 RPM decreases as the load increases, with times of 38.50, 35.72, 28.19, 24.72, and 21.88 seconds for loads of 1 kg, 2 kg, 3 kg, and 4 kg, respectively. The overall findings suggest that biodiesel from the rice bran and soybean oil blend is more efficient than pure soybean oil biodiesel, indicating its potential for more effective use in IC engines. [ABSTRACT FROM AUTHOR]

This research paper investigates a novel triangular honeycomb thermochemical energy storage reactor for low- and medium-temperature applications in buildings, emphasizing its potential to enhance sustainable heating. Using a validated 3D numerical model, the reactor's performance is analyzed in depth across various configurations, focusing on key parameters such as energy storage density, pressure drop, internal air flow distribution, and round-trip efficiency. Results show that the reactor achieved an energy storage density of 872 kJ/kg and a round-trip thermal efficiency of 41.51% under optimal conditions. Additionally, the triangular honeycomb reactor (30°, 60, and 90°) configuration achieved the highest temperature lift of 48.7 °C. In a feasibility analysis for residential heating in northern China, the reactor with 30°, 60°, and 90° angles required 24.91% less volume to meet daily heating demands compared to other configurations. This study contributes valuable insights for the development of efficient, low-carbon heating solutions for low- and medium-temperature applications in buildings, offering interesting advancements in the field of thermochemical energy storage technology. [ABSTRACT FROM AUTHOR]

In hot and arid regions like the Saharan area, effective methods for cooling and humidifying intake air are essential. This study explores the utilization of a water trickle cooler as a promising solution to meet this objective. In particular, the HASSI MESSAOUD area is considered as a testbed. The water trickle cooler is chosen for its adaptability to arid conditions. Modeling results demonstrate its effectiveness in conditioning air before it enters the compressor. The cooling system achieves a significant temperature reduction of 6 to 8 degrees Celsius, enhancing mass flow rate dynamics by 3 percent compared to standard cases without cooling. Moreover, the cooling system contributes to a remarkable 10 percent reduction in power consumption of gas turbines and a notable 10 percent increase in turbine efficiency. These findings highlight the potential of water trickle coolers in improving the performance and efficiency of gas turbine systems in hot and dry climates. [ABSTRACT FROM AUTHOR]

Plastic waste is a rich source of hydrocarbons that can be converted into bio-oil through pyrolysis. In this study, bio-oil was produced by pyrolysis of waste-polypropylene using spent FCC catalyst. Gas chromatography-mass spectrometry (GC–MS) analysis revealed that catalytically produced oil has the majority of compounds in the hydrocarbon range of C6–C18. The catalytic pyrolysis oil was blended with conventional fuel (diesel) to extensively investigate its suitability as a fuel substitute in a single-cylinder, four-stroke, 3.5 kW, diesel internal combustion (IC) engine. Furthermore, four fuels, i.e., CF100PO00 (pure diesel), CF90PO10 (10% v/v pyrolysis oil blended with diesel), CF85PO15 (15% v/v pyrolysis oil blended with diesel), and CF80PO20 (20% v/v pyrolysis oil blended with diesel), were tested in IC diesel engine for performance, combustion, and exhaust emission analysis at 1500 rpm. The tests were carried out at five loads, i.e., 1, 5, 10, 15, and 20 Nm. It was found that CF90PO10 produced 6.61% higher brake thermal efficiency (BTE), whereas CO2 exhaust emission decreased by 20% for CF80PO20 with respect to the pure diesel. Diesel blends with plastic pyrolysis oil can be a promising biofuel to improve engine performance and combustion characteristics without any significant engine modification. [ABSTRACT FROM AUTHOR]

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Solar thermal collectors are being widely used for water heating applications in domestic, commercial, and industrial sectors. The main drawback of these collectors is their low thermal efficiency. The thermal efficiency of these collectors can be significantly increased by enhancing the heat transfer fluid’s thermal properties. This problem can be overcome by homogeneous mixing of nanoparticles in the base fluid such as water. The fluids with nanoparticles have better heat transfer efficiency and thermo-physical properties as compared to monofluid (water). In this study, the percent rise in thermal conductivity of the nanofluids is measured through experimentation by dissolving carbon nanotubes (CNTs) as nanoparticles in different concentrations (v/v %) inside the base fluid. The nanofluids are characterized by using the computer controlled thermal conductivity of liquids and gases unit, (TCLGC) by varying the CNTs sample composition from 0.01-0.05 v/v %. The results show that the inclusion of CNTs as nanoparticles significantly improves the thermal conductivity of nanofluids. Moreover, when CNTs are used at 0.05 v/v% inside a 100 ml sample solution, the highest increase in thermal conductivity is observed as 72%. [ABSTRACT FROM AUTHOR]

This paper aims to examine the effect of a biodiesel blend (Bio20) substitute for diesel on methanol dual-fuel HCCI engine performance. In this work, the existing CI engine is modified into a dual-fuel HCCI engine by attaching the carburetor to the inlet manifold for the supply of methanol. Fuel Jet No. 60 in the carburetor was used to provide a predetermined amount of methanol fuel. The mixture of methanol and air is ignited by diesel/Bio20 injection at the end of the compression stroke. Experimental results showed that methanol with diesel increased ignition delay (ID) and reduced NOX. However, HC, smoke opacity and CO emissions increased drastically compared to a conventional diesel engine. Conversely, methanol with Bio20 reduced ID and promoted combustion helping to reduce smoke opacity, HC and CO emissions. In terms of brake thermal efficiency (BTE) Bio20 instead of diesel gave better performance for a methanol dual-fuel HCCI engine. [ABSTRACT FROM AUTHOR]

The design and optimization of blast furnace (BF) profiles generally rely on limited empirical knowledge and experience. Such exercise can now be improved by means of process modeling and optimization. In this work, the effect of furnace profile on BF performance is numerically investigated across a wide range of furnace volumes (500 to 6000 m3), focusing on the ratio of effective height to belly diameter (H/D ratio). This is done based on the recently developed 3D multi-fluid BF process model. The results indicate that the optimized H/D ratio under different furnace volumes can be determined by minimizing the total energy consumption, namely, the summation of chemical and physical energy consumptions. Comparative analysis indicates that the industrial data on the variation of H/D ratio with furnace volume, collected over years, can be reproduced quantitatively by the current model. The increase in BF size or volume results in high thermal energy efficiency and low coke rate, primarily attributed to the reduced heat dissipation from the top gas and furnace wall. But there exists a size threshold between small and large BFs, approximately 2000 m3 under the conditions considered. Beyond this threshold, the BF performance and in-furnace states do not change significantly. Optimum BF profile needs to consider the coupled effect of H/D ratio and effective furnace volume. [ABSTRACT FROM AUTHOR]

Shipping containers that remain in ports after exporting or importing products cause an environmental and logistical problem. Transporting them to the port of origin is costly; therefore, some of them are stored in the regions of destination. Recycling or reusing them in an efficient and sustainable way represents a clean alternative. The purpose of this article is to analyze the feasibility and impact of implementing different insulating configurations on the energy demands required by a house based on a construction with standardized shipping containers. More specifically, it assesses the impact of the different orientations in which the dwelling can be arranged, depending on the location and its meteorological data. To this aim, a construction model will be developed in which first, the geometrical parameters are defined, and second, the energy characteristics are identified. The results show that, in Southwest Europe, the western orientation generates a saving of 10% of the energy demand compared to the less favourable orientation, which is the southern one. [ABSTRACT FROM AUTHOR]

Solar energy is one of the main renewable energy resources due to its abundance. It can be used for two purposes, thermal or photovoltaic applications. However, when the resource obtained is mixed, it is called photovoltaic thermal hybrid, where the solar panels generate electricity and are provided with a heat exchanger to absorb energy through a water flow. This is one of the techniques used by the scientific community to reduce the excess temperature generated by solar radiation in the cells, improving the electrical efficiency of photovoltaic systems and obtaining fluid with higher temperature. In this work, the thermal behavior of a heat exchanger equipped with fins in its interior to increase the thermal efficiency of the system was analyzed using CFD (Computational Fluid Dynamics). The results showed that the average fluid outlet temperature was 75.31 °C, considering an incident irradiance of 1067 W / m 2 and a fluid inlet temperature of 27 °C. The operating conditions were obtained from published experimental studies, achieving 97.7% similarity between the two. This was due to the boundary conditions of the heat flux (1067 W / m 2 ) impinging directly on the coupled cells and the heat exchanger in a working area of 0.22 m 2 . [ABSTRACT FROM AUTHOR]

This work demonstrates the potential of CO2 + SiCl4 binary mixture as a working fluid for power generation cycle. Recompression Brayton cycle configuration is considered due to its proven record of high performance for medium- to high-temperature sources. The objective of this study is to assess the thermodynamic performance of a recompression Brayton cycle using a CO2 + SiCl4 binary mixture as a working fluid, particularly under warm climate conditions. The cycle is simulated using the Peng–Robinson equation of state in Aspen Hysys (v11) software, and the model is validated by comparing VLE data against experimental data from the literature. The analysis involves the assessment of cycle's thermal efficiency and exergy efficiency under warm climatic conditions, with a minimum cycle temperature of 40 °C. The results demonstrate a notable improvement in the cycle's thermodynamic performance with CO2 + SiCl4 binary mixture compared to pure CO2. A small concentration (5%) of SiCl4 in CO2 increases the thermal efficiency of the cycle from 41.7% to 43.4%. Moreover, irreversibility losses in the cooler and the heat recovery unit are significantly lower with the CO2 + SiCl4 binary mixture than with pure CO2. This improvement enhances the overall exergy efficiency of the cycle, increasing it from 62.1% to 70.2%. The primary reason for this enhancement is the substantial reduction in irreversibility losses in both the cooler and the HTR. This study reveals that when using a CO2 + SiCl4 mixture, the concentration must be optimized to avoid condensation in the compressor, which can cause physical damage to the compressor blades and other components, as well as increase power input. This issue arises from the higher glide temperature of the mixture at increased SiCl4 concentrations and the limited heat recovery from the cycle. [ABSTRACT FROM AUTHOR]

In the last few decades, the problem of pollution resulting from human activities has pushed research toward zero or net-zero carbon solutions for transportation. The main objective of this paper is to perform a preliminary performance assessment of the use of hydrogen in conventional turbine engines for aeronautical applications. A 0-D dynamic model of the Allison 250 C-18 turboshaft engine was designed and validated using conventional aviation fuel (kerosene Jet A-1). A dedicated, experimental campaign covering the whole engine operating range was conducted to obtain the thermodynamic data for the main engine components: the compressor, lateral ducts, combustion chamber, high- and low-pressure turbines, and exhaust nozzle. A theoretical chemical combustion model based on the NASA-CEA database was used to account for the energy conversion process in the combustor and to obtain quantitative feedback from the model in terms of fuel consumption. Once the engine and the turbomachinery of the engine were characterized, the work focused on designing a 0-D dynamic engine model based on the engine's characteristics and the experimental data using the MATLAB/Simulink environment, which is capable of replicating the real engine behavior. Then, the 0-D dynamic model was validated by the acquired data and used to predict the engine's performance with a different throttle profile (close to realistic request profiles during flight). Finally, the 0-D dynamic engine model was used to predict the performance of the engine using hydrogen as the input of the theoretical combustion model. The outputs of simulations running conventional kerosene Jet A-1 and hydrogen using different throttle profiles were compared, showing up to a 64% reduction in fuel mass flow rate and a 3% increase in thermal efficiency using hydrogen in flight-like conditions. The results confirm the potential of hydrogen as a suitable alternative fuel for small turbine engines and aircraft. [ABSTRACT FROM AUTHOR]

Thermal simulation is essential in wire-arc-directed energy deposition (W-DED) to accurately estimate temperature distributions, impacting residual stress and distortion in components. Proper calibration of simulation models minimizes inaccuracies caused by varying material properties, machine settings, and environmental conditions. The lack of standardized calibration methods further complicates thermal predictions. This paper introduces a novel calibration method integrating both machine learning, as the high-fidelity (HF) model, and response surface modeling, as the low-fidelity (LF) model, within a multi-fidelity (MF) framework. The approach utilizes Bayesian optimization to effectively explore the search space for optimal solutions. A two-tiered model employs the LF model to identify feasible regions, followed by the HF model to refine calibration parameters, such as thermal efficiency (η), convection coefficient (h), and emissivity (ε), which are difficult to determine experimentally. A three-factor Box–Behnken design (BBD) is applied to explore the design space, requiring only thirteen parameter configurations, conserving resources and enabling robust model training. The efficacy of this MF model is demonstrated in multi-layer W-DED calibration, showing strong alignment between experimental and simulated temperatures, with a mean absolute error (MAE) of 7.47 °C. This method offers a replicable framework for broader additive manufacturing processes. [ABSTRACT FROM AUTHOR]