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Herein, (CH3)4NMnCl3 doped with Sb3+ single crystals were grown at room temperature. The crystal structure was confirmed by the single-crystal X-ray diffraction at 293 K. The doping of Sb3+ not only improves the excitation intensity in the blue-light region but also red emission only from Mn2+. The emission intensity (Ie) of (CH3)4NMnCl3:0.5%Sb3+ is about 1.5 times higher than that of (CH3)4NMnCl3. The internal and external quantum yield (IQY and EQY) values excited by 450 nm light for the former are 78.6% and 16.0%, which are much higher than those of the latter (56.3% and 10.7%), indicating that Sb3+ can effectively transfer energy to Mn2+. Moreover, the doping of Sb3+ is beneficial to the thermal stability. The Ie of (CH3)4NMnCl3:0.5%Sb3+ at 150 °C is about 1.2 times higher than that of (CH3)4NMnCl3 at 25 °C. Meanwhile, the white LED based on (CH3)4NMnCl3:0.5%Sb3+ also exhibits good optoelectronic performance. Hence, this work provides a new strategy to explore hybrid manganese(II) chlorides for white LEDs. [ABSTRACT FROM AUTHOR]

Herein, (CH3)4NMnCl3 doped with Sb3+ single crystals were grown at room temperature. The crystal structure was confirmed by the single-crystal X-ray diffraction at 293 K. The doping of Sb3+ not only improves the excitation intensity in the blue-light region but also red emission only from Mn2+. The emission intensity (Ie) of (CH3)4NMnCl3:0.5%Sb3+ is about 1.5 times higher than that of (CH3)4NMnCl3. The internal and external quantum yield (IQY and EQY) values excited by 450 nm light for the former are 78.6% and 16.0%, which are much higher than those of the latter (56.3% and 10.7%), indicating that Sb3+ can effectively transfer energy to Mn2+. Moreover, the doping of Sb3+ is beneficial to the thermal stability. The Ie of (CH3)4NMnCl3:0.5%Sb3+ at 150 °C is about 1.2 times higher than that of (CH3)4NMnCl3 at 25 °C. Meanwhile, the white LED based on (CH3)4NMnCl3:0.5%Sb3+ also exhibits good optoelectronic performance. Hence, this work provides a new strategy to explore hybrid manganese(II) chlorides for white LEDs. [ABSTRACT FROM AUTHOR]

To enhance the ignitability and burning rate of ammonia-fueled spark ignition engines, it is an effective way to adopt active pre-chamber (PC) ignition with high-reactivity fuel. Therefore, in this paper, the ammonia combustion characteristics using methanol-enriched active PC ignition were investigated, based on optical engine experiments with simultaneous in-cylinder flame imaging and pressure measurement. Results show that the overall combustion process is characterized by a three-stage heat release: (I) jet flame controlled combustion; (II) ammonia flame propagation; (III) post jet induced combustion. In stage I, methanol active PC jets with high-momentum and high-reactivity are discharged to ignite MC ammonia mixture, contributing to the first peak of heat release rate. In stage II, ammonia turbulent flame propagation dominates the combustion. In stage III, post jets induce the third peak of heat release rate. In this way, with a minimal methanol energy ratio (ER) of lower than 10 %, stable and fast ammonia combustion is achieved under stoichiometric (λ MC = 1) and lean-burn (λ MC = 1.2) condition, with cyclic variation of indicated mean effective pressure (IMEP) lower than 5 %, flame probability higher than 80 % and maximum global flame speed of about 4 m/s. A highest IEMP of 0.72 MPa and a peak indicated thermal efficiency (η it) of 30 % is obtained at λ MC = 1 and λ MC = 1.2, respectively. However, at the rich limit of λ MC = 0.9 and lean limit of λ MC = 1.4, the quenching of jet flames leads to weak ignition and unstable combustion, which is identified by reduced flame probability distribution and increased cyclic variation of IMEP. In addition, to ensure the cyclic combustion stability, there is also an operating range of methanol ER. At λ MC = 1.2, unstable ignition and deteriorated combustion occur below the lower limit of ER = 6 % and above the upper limit of ER = 17 %. This paper can provide data support and operation strategy for the combustion improvements of ammonia-methanol active jet ignition engines. • Methanol active jet-ignited ammonia combustion in optical engine was studied for the first time. • Ammonia in-cylinder combustion features a three-stage heat release. • Stable and fast ammonia combustion is achieved under stoichiometric and lean-burn conditions. • Jet flame quenching leads to unstable combustion with a reduced flame probability. [ABSTRACT FROM AUTHOR]

High temperature corrosion and slag deposition significantly reduce the thermal efficiency and lifespan of biomass-fired boilers. Surface modification with protective coatings can enhance boiler performance and prevent commercial losses due to maintenance and damage. This review focuses on the development of corrosion-resistant coatings (CRCs) and anti-slagging coatings (ASCs) over the past decade. CRCs are explored through thermal spray processes that include arc spray, atmospheric plasma spray (APS), high-velocity oxygen fuel (HVOF), detonation gun (D-gun™), and cold spray. Studies on alloys, ceramics, and ceramic–metal composites are summarised, highlighting the high temperature corrosion prevention mechanisms and discussing new coating materials. ASCs are reviewed in the context of advancements via thermal spray and slurry spray methods. The mechanisms for slag reduction, testing methods to evaluate ASC effectiveness, and the necessary architecture for preventing slag deposition are examined. A lab-based rig simulating fly ash deposition onto water-cooled coating coupons for anti-slagging investigations is also presented. Further research is needed to develop and evaluate materials for ASCs effectively. [ABSTRACT FROM AUTHOR]

Demand for electricity and cooling is increasing due to population growth, which in turn increases pollution. Renewable energy sources are gaining popularity due to their lower levels of pollution. Resource utilisation efficiency is an important factor in maximising the efficiency of low-temperature heat sources. In this study, a vapour absorption cooling cycle and a Kalina power cycle were merged. At the economiser, heat is recovered from the heat exchanger and divided into two basic solution streams. The high-pressure flow passes through the boiler evaporator to produce wet steam, while another stream is throttled to an intermediate pressure. The thermal efficiency of the cycle improves with increasing separator temperature, separator pressure, concentration, and heat recovery temperature, but there is an optimal separator temperature for resource utilisation capacity. Increasing separator pressure and heat recovery temperatures improves resource utilisation efficiency. The proposed cycle has a better temperature match in the heating process. The resource utilisation efficiency of the present cycle is 31.13%, which is 90.63% higher than the reference study. [ABSTRACT FROM AUTHOR]

Flat-plate solar collectors (FPSC) are commonly used for low-temperature heating applications, making system modeling and sensitivity analysis crucial. However, most sensitivity analyses for these collectors are conducted under steady-state conditions. Because of the inherently dynamic nature of ambient conditions, dynamic modeling and sensitivity analysis are needed to better understand and determinate important influencing design parameters. This study presents a comprehensive parametric analysis using a dynamic model of the solar flat-plate collector. The impact of deviations from nominal values of each parameter on system performance and final storage tank temperature is investigated. The findings reveal that pitch tube and absorber thickness significantly influence system efficiency, with a 20% deviation in each parameter resulting in a 10% efficiency change. Moreover, ambient temperature and irradiance have a high impact, causing changes of over 10%. Additionally, a multiparameter sensitivity analysis utilizing the Monte-Carlo method (MPSA) is employed to assess the relative importance of each parameter on FPSC performance. The results highlight that system efficiency is highly sensitive to absorber thickness, while tube pitch, ambient temperature and solar irradiance are crucial for tank temperature. The MPSA is further applied across various ambient temperatures (ranging from 5 to 35 degrees) to determine changes in parameter sensitivity indices. The outcomes indicate that at lower ambient temperatures, certain parameters, such as solar irradiance and tube pitch, exhibit increased sensitivity. However, the sensitivity of system efficiency to all parameters remains relatively constant across different ambient temperatures. [ABSTRACT FROM AUTHOR]

• Residential heat pumps in cold climates were analyzed through an in-house model. • CO 2 -based mixtures are used as refrigerant of a combined demand heat pump. • The refrigerant mixture of 90% of R32 and 10% of CO 2 obtained the best performance. • Refrigerant mixtures rich in CO 2 reduced the heat pump pressure ratio. • CO 2 -rich refrigerant mixtures were able to return more compact heat pumps. Extremely cold climates subject residential heat pumps to significant temperature differences between the heat source and the ambient being heated, which may lead to system failure and reduced compressor performance. The present study considers the possibility of improving the performance of heat pump systems that are simultaneously used for residential space and domestic water heating while subjected to climates varying from -25 °C to 5 °C by exploring the use of zeotropic mixtures. CO 2 -based binary mixtures composed of low-GWP (global warming potential) refrigerants are considered – R32, R1234yf, and R290 – aiming to benefit from environmentally friendly and flame suppressants characteristics of CO 2 , as well as the improved thermal efficiency granted by the addition of a secondary refrigerant. A thermodynamic model was developed for a standard vapor-compression heat pump cycle and used to maximize the coefficient of performance limited by the minimum pinch point in the heat exchangers. Our analysis explores the effect of several parameters, such as, the mixture components, mass fractions, space and water heating demands, and heat source temperature on the heat pump's performance. For cold climates, the mixture of R32 (90%)/CO 2 (10%) yields the highest COP and CO 2 -rich mixtures exhibit the lowest. However, by increasing the mass fraction of CO 2 within the zeotropic mixture, the pressure ratio of the heat pump was improved. When considering combined performance criteria, such as the volumetric heating effect and the total heat delivered related to heat pump size, CO 2 -rich mixtures tend to allow more compact systems, especially in colder climates. [ABSTRACT FROM AUTHOR]

This research paper details an experimental study on airflow dynamics in a solar air heater. The heater's design incorporates unique, discrete V‐shaped ribs with staggered elements to enhance thermal performance. The study investigates the influence of various roughness parameters on flow characteristics. These parameters include a relative coarseness pitch (P/e) ratio of 12, a rib inclination angle (α) of 60°, a relative coarseness height (e/Dh) of 0.043, and a staggered element arrangement with a positioning ratio (p′/P) of 0.65. Additionally, the investigation includes scenarios with three gaps (Ng) between elements and a gap‐to‐rib width (g/e) ratio of 4. The research focuses on how changes to the Reynolds number, ranging from 3000 to 14,000, and alterations to the ratio of staggered element positioning to rib height (r/e), from 2 to 5, impact the flow dynamics. The outcomes indicate a significant boost in heat transfer performance, with the Nusselt number rising to 3.76 compared with a conventional smooth duct. The highest thermal efficiency recorded was 86%, at an r/e ratio of 3.5. These results underscore the potential of using discrete V‐ribs with staggered elements in rectangular ducts to improve heat transfer efficiency. [ABSTRACT FROM AUTHOR]

Heat exchanger research is mainly exploited to develop and optimize new engineering systems with high thermal efficiency. Passive methods based on nanofluids, fins, wavy walls, and the porous medium are the most attractive ways to achieve this goal. This investigation focuses on heat transfer and entropy production in a nanofluid laminar flow inside a plate corrugated channel (PCC). The channel geometry comprises three sections, partially filled with a porous layer located at the intermediate corrugate channel section. The physical modeling is based on the laminar, two‐dimensional Darcy–Brinkman–Forchheimer formulation for nanofluid flow and the local thermal equilibrium model for the heat equation, including the viscous dissipation term. Numerical solutions were obtained using ANSYS Fluent software based on the finite volume technique and the appropriate meshed geometries. The numerical results are validated with theoretical, numerical, and experimental studies. The simulations are performed for CuO–water nanofluid and AISI 304 porous medium. The coupled effects of porous layer thickness (δ), Reynolds number (Re), and nanoparticle fraction (φ) on velocity, streamlines, isotherm contours, Nusselt number (Nu), and entropy generation (S) are analyzed and illustrated. The simulation results demonstrate that heat transfer enhancement in clear PCC can be achieved using a porous layer insert. For the porous thickness range of [0.1–0.6], the corresponding range of average Nusselt number increase is [35.7%–176.9%], and the average entropy generation is [105.4%–771.9%]. The effect of the Reynolds number is more important in a porous duct than in a clear one. For δ = 0.4 and φ = 5%, the increase of Re in the range of [200–500] induces an increase in average Nusselt number in the range of [80.9%–108.4%] and average entropy in [222.9%–309.1%] comparatively to clear PCC. The effect of φ is practically the same for porous and clear channels. For φ = 5%, the increase on average Nu is about 9%, and entropy generation is 5%. Accordingly, important improvements in heat transfer in PCC can be achieved through the combined effect of flow Reynolds number and porous layer thickness. [ABSTRACT FROM AUTHOR]

The current research work involves the design and performance assessment of a solar still, which is a conventional single‐slope basin‐type solar still (CSSBTSS) and a modified single‐slope basin‐type solar still (MSSBTSS) under the meteorological conditions of Solan city, Himachal Pradesh, India (30.90° N, 77.09° E). The individual and the combined effect of different sample quantities of sensible Himalayan Rambaan fibers (HRFs) and mass of latent paraffin wax (PW) A48 on the performance of MSSBTSS is evaluated and compared with CSSBTSS. The use of HRF material enhanced the evaporation rate significantly and improved the daytime distillates. Besides, different masses of latent PW filled inside the aluminum tubes improved the nocturnal distillates. For the analysis, three cases have been considered which are, namely: Case 1, solar still with sensible HRFs (MSSBTSS‐HRF); Case 2, solar still with latent PW A48 (MSSBTSS‐PW); and Case 3, solar still with sensible and latent material (MSSBTSS‐HRF‐PW). The results showed that the maximum thermal efficiency for Cases 1 and 2 was improved by 30.02% and 42.41% with five sample quantities of HRF material and 5000 g of PW. For Case 3, the maximum energy efficiency was 90.71% with a gain of 45.16% over CSSBTSS. The economic analysis concluded that the cost per liter of distillate yield produced using MSSBTSS‐HRF‐PW and CSSBTSS is ₹1.5 and ₹1.6, respectively. These outcomes showed the great potential of MSSBTSS‐HRF‐PW approach towards enhancing the overall performance and cost‐effectiveness of solar still. [ABSTRACT FROM AUTHOR]

This study explores the thermal efficiency of high compression ratio Miller cycle engines and the impact of methanol and methanol/gasoline blends on combustion and emissions. Comparative experiments were conducted to investigate the thermal efficiencies of the Miller cycle compared to the conventional Otto cycle at different compression ratios and how methanol affects combustion and emissions. The results show that under high-speed and high-load conditions, the Miller cycle offers higher thermal efficiency and better tolerance to high compression ratios than the Otto cycle. In experiments conducted at 2000 rpm and 0.66 MPa GIMEP, using the Miller cycle with compression ratios of 11.5 and 14.5 increased thermal efficiency by about 0.6 and 0.8 percentage points compared to the Otto cycle. Using methanol/gasoline blends can advance the combustion phase without changing the load, further improving the engine's thermal efficiency. Burning pure methanol under heavy load significantly improves combustion; it increases in-cylinder pressure by about 30%, thermal efficiency by 7.2 percentage points, and NOx emissions by 80% compared to gasoline. Furthermore, using methanol fuel significantly increases nucleation mode particles and decreases accumulation mode particles, with peak values shifting to smaller diameters. [ABSTRACT FROM AUTHOR]

Based on the self-developed hydraulic variable valve mechanism of four-cylinder engine, this paper proposes a variable displacement valve control strategy based on the VOC-CDA mode of electro-hydraulic. The variation rules of in-cylinder pressure, oxygen mass fraction in exhaust gas, torque fluctuation and other parameters in the process of cylinder deactivation cycle and working mode conversion are analyzed, and the control parameters of inlet and exhaust valves at the best cylinder deactivation time are optimized. The energy saving mechanism of variable displacement technology is analyzed from the aspects of indicated thermal efficiency, mechanical efficiency and effective thermal efficiency. Based on the optimal intake and exhaust valve closing time, the engine can improve the fuel economy by 8.7% at medium and small loads. It provides a certain design reference for the development of variable displacement engine based on hydraulic variable valve mechanism. [ABSTRACT FROM AUTHOR]

Thermographic inspection is particularly effective in identifying thermal bridges because it visualizes temperature differences on the building's surface. The focus of this work is on energy-efficient computing for deep learning-based thermal bridge (anomaly) detection models. In this study, we concentrate on object detection-based models such as Mask R-CNN_FPN_50, Swin-T Transformer, and FSAF. We do benchmark tests on TBRR dataset with varying input sizes. To overcome the energy-efficient design, we apply optimizations such as compression, latency reduction, and pruning to these models. After our proposed improvements, the inference of the anomaly detection model, Mask R-CNN_FPN_50 with compression technique, is approximately 7.5% faster than the original. Also, more acceleration is observed in all models with increasing input size. Another criterion we focus on is total energy gain for optimized models. Swin-T transformer has the most inference energy gains for all input sizes (≈ 27 J for 3000 x 4000 and ≈ 14 J for 2400 x 3400). In conclusion, our study presents an optimization of size, weight, and power for vision-based anomaly detection for buildings. [ABSTRACT FROM AUTHOR]

This study conducts a comprehensive numerical investigation into enhancing thermal transfer within square enclosures filled with water-based oxide nanoparticle suspensions, subjected to central sinusoidal heating. Further flow configuration, influenced by an inclined magnetic field, is designed with a focus on enhancing thermal efficiency for engineering applications. Key innovations include the application of sinusoidal heating elements to enhance thermal performance significantly. Computational analysis supported by finite element analysis, quantifies the impact of these parameters on flow dynamics and thermal transmission, presenting a substantial advance in the understanding of nanofluid-filled enclosure thermal management. The study reveals that the undulation of the heating element plays a crucial role in the heat transfer rate, with improvements observed as undulation increases. The introduction of magnetic fields further controls flow distribution and buoyancy effects, as demonstrated by our findings that an increase in the Rayleigh number correlates with enhanced convection, dominating the cavity's thermal dynamics. Additionally, the report outlines the conditions under which the Nusselt number increases, indicating enhanced thermal performance. These insights are pivotal for designing optimized heat transfer systems and energy-efficient applications, setting a new benchmark for thermal management strategies in practical engineering contexts. [ABSTRACT FROM AUTHOR]

The present study details the development of a solar dryer with double pass flat plate solar collector having carbon nanodots (CNDs) coated absorber surface. Among the various concentrations of CNDs (0.1, 0.2, 0.5, 1, and 2%), the 0.5% CNDs coated absorber surface recorded the highest absorptance and lowest reflectance with higher spectral selectivity of 0.933. Hence, the 0.5% coating was selected as the optimum concentration and coated over the absorber surface of flat plate solar air collector. SEM image of black painted surface is clear and smooth and CNDs coated absorber surface is having dispersed particle with rough surface. FTIR absorption peak values revealed that the presence of black paint and CNDs in the 0.5% CNDs coated aluminium sheet. The efficiency of collector coated with 0.5% CNDs was calculated at various air flow rate of 0.008, 0.016, 0.018, and 0.021 kg/s and results revealed that the rise in air flow rate from 0.008 to 0.021 kg/s increased the efficiency from 39.22 to 82.99%. The solar dryer connected with the developed collector was tested for the performance and the drying studies revealed that shrimp and false white sardine required 10 h and 11 h drying time during the experimental studies. [ABSTRACT FROM AUTHOR]

The growing demand for electrical energy in several fields makes it crucial to have a performant and sustainable way of transporting electricity; aluminum wires represent an attractive solution to save weight and reduce economic expenses. Improving the electrical performance of wires is fundamental for their usage in several fields, and graphene represents a candidate solution for this scope. In this paper, a novel graphene coating realized through electrophoretic deposition (EPD) is proposed to improve the thermal and electrical properties of lightweight aluminum wires. Voltages, magnesium salts, and salt concentrations in the deposition bath were varied through a full-factorial plan to determine the role of the EPD parameters in the morphology and performances of the coated wires. A significant variation in the roughness and thickness of the coating was noticed by varying the process parameters because of the presence of hydrogen reactions during the deposition. All scenarios presented a reduction in electrical resistivity ranging from – 2.78% to – 4.01%, showing a statistically significant correlation between roughness and resistivity. All the coated wires presented a noteworthy improvement in thermal performance compared to the as-received wire. The analysis of variance was adopted to evaluate the role of EPD parameters in the morphology and performances. [ABSTRACT FROM AUTHOR]

The results of mathematical modeling of a building's thermal insulation influence on the efficiency of intermittent heating mode are presented. This work aim is to assess the influence of thermal insulation on the efficiency of using the intermittent heating mode for the educational building of the Odessa National Polytechnic University's Heat Engineering Laboratory. The paper analyzes the factors related to improving the efficiency of the programmed heat supply mode. Modeling of the operating modes for heat supply system operated in intermittent heating mode is carried out. There was performed the mathematical modeling of the heating system operation modes for the most unfavorable climatic conditions at low outdoor temperatures, with respective system efficiency indicators obtaining. The potential of energy saving level for administrative, educational, and office buildings depending on the thickness of thermal insulation of external and internal walls is studied. Recommendations have been elaborated for the use of buildings thermal insulation to improve the efficiency of intermittent heating. [ABSTRACT FROM AUTHOR]

The current study aims to amplify the predictive ability of the numerical model developed for a gas turbine engine-based power plants by process of regeneration and intercooling. Artificial neural networks (ANN) and adaptive neuro-fuzzy interface systems (ANFIS) are the two techniques mainly concentrated in this study which were not properly implemented previously. The performance parameters namely, specific power (SP), thermal efficiency (η), and enthalpy based specific fuel consumption (EBSFC) of a Turboprop engine were predicted using thermodynamic parameters namely, pressure ratio (PR), nozzle pressure ratio (NPR), turbine inlet temperature (TIT), for constant regeneration (R), and intercooling (E) efficiencies. The results showed that a high regression result R2 of 0.9831 and 0.9899 was found for the ANFIS model for η for training and testing, respectively. Also, the ANFIS model resulted in best performance of the performance characteristics when compared to ANN. [ABSTRACT FROM AUTHOR]

Conventional preheating methods for large steelmaking ladles typically use natural gas or liquified petroleum gas burners, which often have low thermal efficiencies depending on the fuel and oxidizer used. Common issues with these burners include lower overall bottom ladle temperatures and initiating decarburization in newly lined ladles with carbon‐rich refractory materials caused by the entrainment of air and combusting by‐products. In response to these issues, this study investigates the feasibility of using DC plasma torches for ladle preheating with nitrogen as carrier gas. Numerical models are developed to simulate ladles preheated by plasma torches, considering two variations: a 0.7 and a 1.5 MW torch. Additionally, a comparative model for a natural gas‐heated ladle is developed. The numerical results show that ladles heated by plasma torches achieve higher overall bottom temperatures due to strong convective heat flux, with average bottom temperatures of 983 and 1402 °C for 0.7 and 1.5 MW torch respectively, compared to 874 °C for natural gas heated ladle. The developed models are validated with industrial measurements on full‐sized ladles, confirming the feasibility of using plasma torches for preheating steelmaking ladles to temperatures similar to or higher than those achieved by conventional gas burners. [ABSTRACT FROM AUTHOR]

Warmer and more variable temperatures have been implicated in the recent decline of Atlantic salmon (Salmo salar) in Eastern Canada. To date, we know little on how ecologically relevant thermal fluctuations affect swimming performance in fishes. The goal of this study is to determine the effects of warm versus cool diel thermal variability on swimming efficiency and the speed limit for sustainable aerobically fueled swimming. We acclimated wild S. salar juveniles to a cool and a warm ecologically realistic diel thermal profile (16–21 and 19–24°C), and then tested individuals over a common acute change in temperature (16–24°C). We measured metabolic rate and swimming kinematics at a range of swimming speeds, at five temperatures (16, 18, 20, 22, and 24°C) and calculated swimming efficiency. Our temperature acclimation did not appear to significantly affect energetic and kinematic swimming efficiency, but acute exposure to high temperature did increase overall metabolic rate. It appears that wild S. salar can swim efficiently and sustainably during both acute cool and warm exposures, and after acclimation to diel thermal variation of 16–21 or 19–24°C. [ABSTRACT FROM AUTHOR]

Enhancing the thermal decomposition efficiency and safety of ammonium perchlorate (AP) is of far‐reaching significance in composite propellants. Most catalysts act well on the thermal decomposition of AP, however, synergistically achievements of fastened decomposition and improved mechanical safety are still in challenge. Herein, neutral red (NR) is selected from typical dyes through theoretical calculations, acting as an organic decoration of AP crystal with improved performances. Among the four organic dyes, NR demonstrated the highest adsorption energy and evident charge transfer at the interface. Following preparations through a freeze‐drying technique obtained a quasi‐homogeneous energetic composite (NR‐AP‐5%). The large interaction force between NR and AP promoted the rupture of chemical bonds between Cl and O as proved by TG‐MS, showing excellent energy‐release performance with the decreased exothermic peak from 437.0 to 355.5 °C. Correspondingly, the activation energy is reduced from 213.59 to 107.72 kJ mol−1, with largely increased heat release from 447.29 to 1014.86 J g−1. In addition, the inert decoration of NR endowed considerable advances in the safety performances of AP, achieving remarkably improved impact and friction sensitivity of 35 J and 288 N, respectively. This unique assembly structure provides a novel strategy to achieve high‐effective catalysis for functional propellants. [ABSTRACT FROM AUTHOR]

In this study, the split-channel supercharge and fuel-air mixing technology (SCS-FAM) is firstly proposed for large-bore ammonia (NH 3)-hydrogen (H 2) engine, which involves the separation of fuel and air intake ports to mitigate the risk of H 2 backfire in intake system. We explored the activity stratification under different intake schemes and H 2 blend ratios through simulation, as well as how it affects the NH 3 –H 2 combined combustion characteristics including in-cylinder flow turbulence, temperature, concentration, and key intermediates distribution. The results show that in Scheme 2 when air entered the high swirl ratio intake 1 and fuel entered the low swirl ratio intake 2, a rich mixture was formed near the spark plug, accompanied by localized NH 3 thermal reforming phenomena, which improved the activity distribution of H 2. Additionally, the strong swirl promoted combustion in the squish zone and significantly shortened the post-combustion period. Scheme 2 achieved a higher indicated thermal efficiency (ITE) than Scheme 1 with a small amount of H 2 addition, with the highest ITE of 42.1% obtained at 15 vol% H 2 blend ratio. Notably, the addition of H 2 promoted NH 3 consumption and the generation of active radicals, resulting in reduced N 2 O emissions during the expansion stroke, but causing an increase in NO emissions. • Split-channel supercharge and fuel-air mixing technology is proposed to prevent H 2 backfire. • Different NH 3 –H 2 blend mixtures are compared and higher thermal efficiency is reached by lower H 2 fraction. • The localized ammonia-rich auto-thermal reforming improves the activity distribution of NH 3 –H 2 mixture. • Improved in-cylinder swirl could enhance the flame propagation in squish zone and reduce post-combustion. [ABSTRACT FROM AUTHOR]

This study presents a sophisticated numerical simulation model for a forced circulation solar water heating system (FC-SWHs), specifically designed for the unique climatic conditions of Algeria. The model aims to cater to the hot water needs of single-family houses, with a daily consumption of 246 L. Utilizing a dynamic approach based on TRNSYS modeling, the system's performance in Ain Temouchent's climate was scrutinized. The model's validation was conducted against literature results for the collector outlet temperature. Key findings include a maximum monthly average outlet temperature of 38 °C in September and a peak cumulative useful energy gain of 250 W in August. The auxiliary heating system displayed seasonal energy consumption variations, with the highest rate of 500 kJ/hr in May to maintain the water temperature at 60 °C. The energy input at the storage tank's inlet and the consistent high-level energy output at the hot water outlet were analyzed, with the former peaking at 500 W in May. The system ensured an average water tank temperature (hot, middle and bottom) and water temperature after the mixer, suitable for consumption, ranging between 55 °C and 57 °C. For applications requiring cooler water, the mixer's exit temperature was maintained at 47 °C. The study's key findings reveal that the TRNSYS model predicts equal inlet and outlet flow rates for the tank, a condition that is particularly significant when the system operates with high-temperature water, starting at 55 °C. The flow rate at this temperature is lower, at 7 kg/hr, while the water mass flow rate exiting the mixer is higher, at 10.5 kg/hr. In terms of thermal performance, the system's solar fraction (SF) and thermal efficiency were evaluated. The results indicate that the lowest average SF of 54% occurs in July, while the highest average SF of over 84% is observed in September. Throughout the other months, the SF consistently stays above 60%. The thermal efficiency of the system varies, ranging from 49 to 73% in January, 43–62% in April, 48–66% in July, and 53–69% in October. The novelty of this research lies in its climate-specific design, which addresses Algeria's solar heating needs and challenges. Major contributions include a thorough analysis of energy efficiency metrics, seasonal auxiliary heating demands, and optimal system operation for residential applications, supporting Algeria's goal of sustainable energy independence. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the thermal behavior of water-based nanofluid flow over a rotating surface, focusing on understanding the effects of different types of nanoparticles on thermal efficiency, considering Catteneo–Christov heat flux and variable viscosity effects. By considering four distinct nanoparticles — silicon dioxide, titanium dioxide, copper oxide and zinc oxide — this study aims to provide insights into how nanoparticle addition influences heat production, thermal boundary layer thickness and overall thermal performance. The study employs computational methods by utilizing the BVP Midrich algorithm for the solution procedure. The computational approach allows for a detailed investigation of the thermal behavior of nanofluid flows across a rotating surface under varying conditions. The study concludes that adding nanoparticles in the base liquid increases heat production in the system, resulting in enhanced thermal boundary layer thickness. The comparative analysis shows that different nanoparticle types exhibit varying effects on thermal efficiency, suggesting that careful selection of nanoparticles can optimize heat transport and thermal management processes. Moreover, it seems there’s a noteworthy downfall in the thermal profile concerning the relaxation time parameter, whereas a converse trend is observed for Biot number. [ABSTRACT FROM AUTHOR]

This study explored the recovery of oil from lemon peel biomass and then tested it in a spark ignition as a substitute for gasoline. The study adopted the micro-arc oxidation coating technique, intending to improve the engine performance of the lemon peel oil-gasoline blends. The oil was recovered from discarded lemon peel biomass using steam distillation and then tested in the engine as a fuel by blending it with gasoline at volume ratios of 10, 20, and 30%. An endoscopic visualization approach was employed in this research work to assess the combustion initiation and flame characteristics of gasoline and lemon peel oil blends under different test conditions. Compared to gasoline and blends comprising 20 and 30% lemon peel oil, the 10% lemon peel oil mix produced higher thermal efficiency and lower emissions. The optical analysis demonstrated that premixed combustion with the 10% blend was found to be the highest, resulting in improved combustion and subsequently increased cylinder pressure. To improve the engine performance of the lemon peel oil blends with higher substitution (20 and 30%), the piston was coated with a ceramic coating. A novel technique, namely the micro-arc oxidation technique, was utilized for the coating. The coated piston engine fueled with a 20% lemon peel oil blend showed a 3% and 4.69% increase in thermal efficiency compared to the uncoated piston fueled with a 20% blend and sole gasoline, respectively. The hydrocarbon and carbon monoxide emissions of the engine with a coated piston fueled by the 20% lemon peel oil blend were reduced by 12.7% and 12%, respectively, as compared to gasoline operation in the engine with an uncoated piston. [ABSTRACT FROM AUTHOR]

Dilution combustion technology is an effective method for improving the thermal efficiency of methanol engines. To further explore the application potential of this technology, this study employed blending dissociated methanol gas and optimizing dilution working fluids to enhance the dilution combustion performance of the engine. The results indicate that, under the same dilution ratio, increasing the blending ratio of dissociated methanol gas and reducing the EGR proportion in the dilution working fluid lead to advancements in CA10, CA50, and CA90, a decrease in HC emissions and BSFC, and an expansion of the dilution combustion limit, while also resulting in an increase in NOx emissions. When the dilution ratio is extended to the combustion limit and the ignition timing is optimized, the optimal trade-off between BSFC and BSNOx for different blending ratios of dissociated methanol gas is achieved using air as the dilution working fluid. At this point, when the blending ratios of dissociated methanol gas are 7.5% and 15% compared to 0%, BSFC decreases by 3.1% and 5.7%, respectively, while NOx emissions also experience a slight decline. [Display omitted] • Effect of blending dissociated methanol gas on engine performance. • Effect of dilution working fluid on engine performance. • Optimization of ignition timing and dilution ratio for BSFC and COV IMEP. • The optimal compromise effect on BSFC and BSNOx at the dilution limit. [ABSTRACT FROM AUTHOR]

The utilization of nanofluids in thermal engineering presents a promising avenue for addressing high-temperature challenges. Similarly, many industries still use air-cooled intercoolers for multistage air compressors which results in lower efficiency of the system. This study explores the application of Al2O3 nanoparticles mixed with water as a base fluid to analyze the effect of intercooling in a two-stage reciprocating air compressor. The study employs a shell and tube heat exchanger with parallel and counter flow conditions. The computational analysis, facilitated by computational fluid dynamic software compares the thermal conductivity and heat transfer rates of water and Alumina Oxide based nanofluid to an air-intercooled system. Additionally, the study evaluates the isothermal and volumetric efficiency of the compressor, along with the work requirements for its low-pressure and high-pressure cylinders without using a chiller or external medium. While, achieving ideal intercooling conditions remains elusive in practical experiments, ongoing research focuses on enhancing intercooler efficiency through various nanofluid techniques. The findings suggest notable enhancements in isothermal efficiency by 7.18% and reductions in work input by 3.4% for the air compressor under specified parameters. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the performance of engines and the produced emissions by adding diethylene glycol dimethyl ether (DGM), an oxygen-rich additive with a high cetane number, into n-pentanol and diesel fuel blends. Using pure diesel (OXG0) as the benchmark, five fuel blends were tested in a single-cylinder compression ignition engine. While always keeping a diesel ratio of 70%, the blends displayed a range of DGM content ranging from 5 to 20%. Analysis showed that by 1.27% in contrast to pure diesel, the mix of 70% diesel, 10% n-pentanol and 20% DGM (OXG4) enhanced brake thermal efficiency (BTE). Moreover, OXG4 was shown to be efficient in lowering CO and NOx emissions under all load conditions, therefore demonstrating its ability to control negative emissions. Still, when the DGM content rose, CO2 emissions clearly started to rise—probably because of improved combustion efficiency. Furthermore, the study showed that compared to OXG0 other blends—OXG1, OXG2 and OXG3—often produced greater brake-specific fuel consumption and slightly worse BTE. The findings highlight the feasibility of DGM as a suitable additive to enhance diesel fuel blends to get better emission characteristics without appreciably compromising engine performance. [ABSTRACT FROM AUTHOR]

A stationary, symmetrical hemispherical solar collector with helical risers is experimentally investigated. Pure water and Ag-CuO/water hybrid nanofluid are used as the working fluid. The nanoparticle's volume fractions are 0.1 and 0.3%, and the flow rates of the working fluid are 1, 1.5, and 2 Lmin−1. A total of 9 tests have been conducted in 9 consecutive days during August 2022. All tests were performed according to ASHRAE standards. The main novelty of this study is the practical use of hybrid nanofluid and helical risers in a solar collector with hemispherical geometry. According to the results, a hemispherical solar collector exhibits hopeful and favorable thermal efficiency due to its particular shape and the unique arrangement of its helical risers. The results show that with the increase in flow rate, the temperature difference between the inlet and outlet of the hemispherical solar collector and the heat exchanger inside storage tank decreases, while the thermal performance of the solar collector increases. Also, when the concentration of nanoparticles increases, the temperature difference between the inlet and outlet of the collector, and the thermal efficiency, increases. The results show that the maximum thermal efficiency of the solar collector is 86.8% and the maximum average temperature of the fluid around the heat exchanger in the storage tank is 79.8 °C, and these results are related to the hybrid nanofluid with a volume fraction of 0.3% and a flow rate of 2 Lmin−1. [ABSTRACT FROM AUTHOR]

Dual fuel combustion has gained attention as a cost-effective solution for reducing the pollutant emissions of internal combustion engines. The typical approach is combining a conventional high-reactivity fossil fuel (diesel fuel) with a sustainable low-reactivity fuel, such as bio-methane, ethanol, or green hydrogen. The last one is particularly interesting, as in theory it produces only water and NOx when it burns. However, integrating hydrogen into stock diesel engines is far from trivial due to a number of theoretical and practical challenges, mainly related to the control of combustion at different loads and speeds. The use of 3D-CFD simulation, supported by experimental data, appears to be the most effective way to address these issues. This study investigates the hydrogen-diesel dual fuel concept implemented with minimum modifications in a light-duty diesel engine (2.8 L, 4-cylinder, direct injection with common rail), considering two operating points representing typical partial and full load conditions for a light commercial vehicle or an industrial engine. The numerical analysis explores the effects of progressively replacing diesel fuel with hydrogen, up to 80% of the total energy input. The goal is to assess how this substitution affects engine performance and combustion characteristics. The results show that a moderate hydrogen substitution improves brake thermal efficiency, while higher substitution rates present quite a severe challenge. To address these issues, the diesel fuel injection strategy is optimized under dual fuel operation. The research findings are promising, but they also indicate that further investigations are needed at high hydrogen substitution rates in order to exploit the potential of the concept. [ABSTRACT FROM AUTHOR]

Combustion and emission characteristics of a heavy-duty single-cylinder ammonia engine with a hydrogen-fueled active pre-chamber ignition system are investigated experimentally at the condition of IMEP 10 bar, 1000 rpm, where effects of spark timing, excess air ratio (λ), and hydrogen energy ratio are tested. Three distinguishable combustion phases are observed, including pre-chamber combustion, turbulent-jet-controlled combustion, and ammonia-chemical-kinetics-controlled combustion. Advancing spark timing makes combustion phases earlier, increasing pressure rise rate, combustion pressure, and NOx emissions. The optimal spark timing for the highest indicated thermal efficiency (ITE) is −12°CA ATDC in the experiment. λ range for stable combustion is 1.1–1.5 and ITE peaks at λ = 1.3. The hydrogen energy ratio, 7.9%∼10.5%, has little influence on the engine performance. However, a low hydrogen energy ratio could increase the risk of misfire. The optimal hydrogen energy ratio is about 9∼10%. • The performance of a hydrogen-jet-ignited heavy-duty ammonia engine is tested. • Three-stage heat release of the hydrogen-jet-ignited ammonia engine is revealed. • Effects of spark timing, λ, and hydrogen energy ratio are uncovered. • λ range for stable combustion is 1.1–1.5 and ITE peaks at λ = 1.3. • The optimal hydrogen energy ratio is about 9–10%. [ABSTRACT FROM AUTHOR]

District heating systems play a pivotal role in providing efficient and sustainable heating solutions for urban areas. In this sense, district heating systems that use geothermal resources have been gaining prominence in recent years, due to the non-intermittent nature of their application, among many other reasons. The present study investigates the thermal performance of novel coaxial pipes in comparison to conventional pipes within district heating distribution networks supplied by geothermal energy. Through experimental simulation and analysis, key thermal parameters such as heat transfer efficiency, thermal losses, and overall system effectiveness are evaluated through laboratory tests developed on a scale model. Experimental analysis concludes that, at a laboratory scale, heat energy efficiency can be improved by around 37% regarding the traditional geothermal distribution network. This improvement translates into a significant economic and environmental impact that has a direct influence on the viability of this type of system in different application scenarios. The results highlight the potential benefits of coaxial pipe designs in enhancing heat transfer efficiency and minimizing thermal losses, thus offering insights for optimizing geothermal district heating infrastructure for improved energy efficiency and sustainability. The novelty of this study lies in the innovative design and experimental validation of coaxial pipes, which demonstrate a 37% improvement in heat energy efficiency over conventional pipe designs in geothermal district heating systems, offering a breakthrough in optimizing heat transfer and minimizing thermal losses. [ABSTRACT FROM AUTHOR]

Hydrogen, as a promising renewable energy source, is considered to have significant potential for achieving the dual-carbon goal. In the present study, a 1D engine model is used to investigate the impact of hydrogen injection pressure and its changing law on the performance of hydrogen engines. The results indicate that under low load conditions, increased hydrogen injection pressure from 5 bar to 25 bar initially improved power performance and fuel economy and then declined them; an injection pressure of 10 bar got the highest power of 51.91 kW and thermal efficiency of 43.25%. Under medium load conditions and high load conditions, increased hydrogen injection pressure from 5 bar to 25 bar, power performance and fuel economy declined. The NOx emission of engine declined gradually with the increase of injection pressure from 5 bar to 25 bar. The NOx emission is reduced by approximately 2.5% as the injection pressure is raised from 5 bar to 15 bar, and then, as the injection pressure continues to increase, the reduction becomes less significant. Additionally, selecting the End Peak curve for hydrogen injection pressure change increased indicated power by 0.4 kW, thermal efficiency by 0.2%, and reduces NOx emission by around 8% than other curves. The study also found that near-zero emissions can be achieved when λ value exceeds 2.5. • Different hydrogen injection pressure and its variation law are investigated. • The effects of different hydrogen injection pressures on engine performance are investigated. • The influences of various hydrogen injection pressure variation law on engine performance are investigated. • The near zero emission conditions of the engine are investigated. [ABSTRACT FROM AUTHOR]

This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the focus was placed on investigating the specific impacts of ethanol and n-butanol additives on diesel engine performance. Research shows that a fuel mixture consisting of 70% diesel, 10% biodiesel, and 20% ethanol reduced NOx emissions by 5.56% compared to pure diesel at 75% load. Furthermore, this study explores the combustion performance of diesel/biodiesel blended with butanol/ethanol. The findings indicate that n-butanol improves thermal efficiency, particularly at 100% load, with the D70B10E20 and D70B10BU20 blends demonstrating thermal efficiencies of 9.94%and 8.72% higher than that of diesel alone, respectively. All mixed fuels exhibited reduced hydrocarbon and CO emissions under different loads, with a notable reduction in hydrocarbon emissions of 34.4% to 46.1% at 75% load. [ABSTRACT FROM AUTHOR]

The combustion optimization problem of the circulation fluidized bed boiler is regarded as a difficult multi-objective optimization problem that requires simultaneously improving the boiler thermal efficiency and reducing the NOx emissions concentration. In order to solve the above-mentioned problem, a new multi-objective optimization framework that incorporates an interpretable CatBoost model and modified slime mould algorithm is proposed. Firstly, the interpretable CatBoost model combined with TreeSHAP is applied to model the boiler thermal efficiency and NOx emissions concentration. Simultaneously, data correlation analysis is conducted based on the established models. Finally, a kind of modified slime mould algorithm is proposed and used to optimize the adjustable operation parameters of one 330 MW circulation fluidized bed boiler. The experimental results show that the proposed framework can effectively improve the boiler thermal efficiency and reduce the NOx emissions concentration, where the average optimization ratio for thermal efficiency reaches +0.68%, the average optimization ratio for NOx emission concentration reaches −37.55%, and the average optimization time is 6.40 s. In addition, the superiority of the proposed method is demonstrated by ten benchmark testing functions and two constrained optimization problems. Therefore, the proposed framework is an effective artificial intelligence approach for the modeling and optimization of complex systems. [ABSTRACT FROM AUTHOR]

Energy demand has increased gradually. Meeting the energy demand through available sources in the country leads to self-sufficiency. Alternate fuel production and implementation-based research have been more concentrated on encountering that demand for CI engine fuels. Here, transesterification produced biodiesel from the Ziziphus mauritiana seed oil is used. While running, the 5.2 kW CI engine with this new neat Ziziphus mauritiana biodiesel (ZMBD) has 8.7% lesser brake thermal efficiency and 4% and 33% higher NOx and smoke emissions than diesel at full load. Therefore, this biodiesel is blended with 10% and 20% by volume of camphor oil biofuel (COBF) to improve the performance. Also, exhaust gas recirculation (EGR) of 10% and 20% is employed for the better result-produced blend. At full load, 80% ZMBD with 20% COBF blend produced 6.9%, 19.8%, and 15.3% increased brake thermal efficiency, maximum heat release rate, and NOx emission and also 19.05%, 23.73%, 5.78%, and 19.75% drop in CO, unburnt HC, CO2, and smoke emission than ZMBD. With this blended fuel operation and 20% EGR employment is produced 52.99% reduction in NOx and a 13.96% reduction in smoke emission with 3.33% increased brake thermal efficiency compared to straight ZMBD. Therefore, this 80% ZMBD and 20% COBF blend with 20% EGR is recommended for the CI engine with improved performance and reduced NOx emission. [ABSTRACT FROM AUTHOR]

The growing need for renewable and sustainable energy sources has prompted researchers to explore alternative fuels for engines traditionally powered by gasoline or diesel. Biodiesel derived from tamarind oil shows great potential as a sustainable fuel due to its renewable and eco-friendly nature. This investigation emphasizes the efficiency, emissions, and combustion characteristics of tamarind seed-based biodiesel blends with magnetite (Fe3O4) nanoparticles in a direct ignition engine. The magnetite nanoparticles in concentrations of 50 and 100 ppm are added to tamarind biodiesel blends with the help of an ultrasonicator. The prepared fuels were tested in a single-cylinder, four-stroke, vertical compression ignition engine. The experimental results revealed that the TME20M100 blend exhibits an increase in brake thermal efficiency by 5.85%, and SFC decreased by 6.18% with the maximum values of HRR and cylinder pressure are 44.5 J/°CA and 69.58 bar, respectively. Additionally, the TME20M100 blend exhibited a significant reduction of 27.32% in CO emissions, 7.93% in HC emissions, 4.05% in NOx emissions, and 3.23% in smoke emissions, as compared to the TME20. This study presents a promising approach to producing high-performance, eco-friendly biodiesel, contributing to the broader adoption of renewable energy sources. [ABSTRACT FROM AUTHOR]

Increases in fossil fuel consumption and the effect of engine emissions on the environment lead researchers to work on alternate methods to control this situation. This present work focuses on evaluating the performance, combustion, and emission characteristics of fish oil (FO)–diesel blends in a mono-cylinder compression ignition engine with Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles added at a concentration of 25 ppm, 50 ppm, and 75 ppm. The results were compared with conventional compression ignition engines with diesel for varying loads at a constant speed of 1500 RPM. An investigation revealed that adding Mg-doped ZnO nanoparticles to FO–diesel blends enhanced the performance and combustion characteristics of CI engines because of the higher surface-to-volume ratio and thermal conductivity of the nano-additives. In addition, Mg-doped ZnO nanoparticles improved brake thermal efficiency (BTE) for biodiesel–diesel blends and lowered brake specific fuel consumption (BSFC) by 2.8% and 14%, respectively, for a B30 Mg-ZnO 75 ppm fuel blend than B100 at full load condition. On the other hand, emissions such as HC, CO, and smoke were reduced by 29%, 31%, and 23%, respectively, for the B30 Mg-ZnO 75 ppm fuel blend at full load condition. Overall, the B30 Mg-ZnO 75 ppm fuel blend was best compared with other blends for improved combustion, performance, and lower exhaust emissions. [ABSTRACT FROM AUTHOR]

For the semi-batch isoperibolic homogeneous exothermic reaction, the dosing rate is an effective method to control the exothermic rate. In this work, the esterification of propionic anhydride and sec-butanol is taken as an example to obtain the heat of reaction by considering the heat of mixing effect. The effect of dosing rates on reaction temperature and heat transfer efficiency are investigated for the semi-batch reaction system. The dosing rate is optimized by kinetic-free thermal runaway criteria based on Ψ number and the νADaREκ-Xac,max & Rymin-Wt plots. The effect of cooling jacket temperature on the optimal dosing rates calculated by the criteria is investigated. The obtained results have been compared with the boundary and temperature diagrams criterion. The results show that safe operation conditions can be approximately obtained when lack of kinetic information for semi-batch reaction process. This work can provide a guidance which can facilitate the optimization of dosing rate to improve reaction efficiency and prevent thermal runaway. [ABSTRACT FROM AUTHOR]

This study presents a thermodynamic analysis of the bottoming cycle in a triple-pressure reheat combined-cycle power plant to evaluate the effects of various design parameters on the cycle performance. The important design parameters include the three inlet pressures and temperatures in the steam turbines, condenser pressure, and pinch point temperature of the heat recovery steam generator. These parameters significantly affect the power output of each steam turbine, which, in turn, influences the overall power output of the combined-cycle power plant. The analysis showed the effect of each parameter on the bottoming-cycle power output and thermal efficiency. Off-design conditions can significantly affect cycle performance, which can be used to understand the behavior of the combined cycle plant. A better understanding of the cycle can help achieve better bottoming-cycle designs that produce higher power outputs and efficiencies. [ABSTRACT FROM AUTHOR]

Helium-xenon (HeXe)-cooled mobile nuclear reactors have promising potential in future low-carbon energy systems. However, there is currently a lack of fast and reliable tools for analyzing the complicated dynamic characteristics of such systems. In this study, we developed a comprehensive dynamic modeling approach for a HeXe-cooled nuclear power system coupled with a closed Brayton cycle (CBC). The system's key components, including the reactor, printed circuit heat exchanger (PCHE), and turbomachinery, are lumped-modeled to capture their time-varying behavior. A step-solving algorithm that incorporates HeXe mass conservation iteration is designed. The verification results demonstrate that the dynamic program is robust and reliable, with each time step converging within 25 iterations and the HeXe mass remaining within the range of 3.755 ± 0.01 kg throughout the simulation meeting the law of mass conservation. Then, a 1500 s frozen start-up simulation for the coupled system is conducted, in which the CBC is started in the first 500 s by increasing the main shaft speed to 40% of the rated value, and then the reactor is started by inserting external reactivity between 500 and 800 s. Both the dynamic process and the steady-state performance after the start-up are analyzed. The results show that the system achieved a stable electrical output of 5.7 MWe with a thermal efficiency of 32.5%. This study lays a solid foundation for future work aimed at improving the overall efficiency and performance of HeXe-cooled nuclear power systems. [ABSTRACT FROM AUTHOR]

A significant challenge in utilizing hydrogen in conventional internal combustion engines is achieving a balance between NOx emissions and brake power output. A lean premixed charge (Lambda ≈ 2.5) allows for efficient and stable combustion with minimal NOx emissions. However, this comes at the cost of reduced power density due to the higher air requirements of the thermodynamic process. While supercharging can mitigate this drawback, it introduces increased complexity, cost, and size. An intriguing alternative is the 2-stroke cycle, particularly in an opposed piston (OP) configuration. This study presents the virtual development of a single-cylinder 2-stroke OP engine with a total displacement of 0.95 L, designed to deliver 25 kW at 3000 rpm. Thanks to its compact size, high thermal efficiency, robustness, modularity, and low manufacturing cost, this engine is intended for use either as an industrial power unit or in combination with electric motors in hybrid vehicles. The overarching goal of this project is to demonstrate that internal combustion engines can offer a practical and cost-effective alternative to hydrogen fuel cells without significant penalties in terms of efficiency and pollutant emissions. The design of this novel engine started from scratch, and both 1D and 3D CFD simulations were employed, with particular focus on optimizing the cylinder's geometry and developing an efficient low-pressure injection system. The numerical methodology was based on state-of-the-art commercial codes, in line with established engineering practices. The numerical results indicated that the optimized engine configuration slightly surpasses the target performance, achieving 29 kW at 3000 rpm, while maintaining near-zero NOx emissions (<20 ppm) and high brake thermal efficiency (~40%) over a wide power range. Additionally, the cost of this engine is projected to be lower than an equivalent 4-stroke engine, due to fewer components (e.g., no cylinder head, poppet valves, or camshafts) and a lighter construction. [ABSTRACT FROM AUTHOR]

Biodiesel has been chosen as a decent alternative to diesel in the context of establishing environmentally pleasant conditions and saving petroleum‐based resources for future generations. It is well‐established that biodiesel‐powered diesel engines may achieve outcomes equivalent to those of diesel engines. The current investigation was conducted to study the effect of injection pressure (190, 210, and 230 bar) and exhaust gas recirculation (EGR) (5%, 10%, and 15%) on a single‐cylinder variable compression ratio (VCR) diesel engine running using a B20 (20% MB + 80% PD) blend of microalgae biodiesel (MABD). This experiment was conducted in two stages. During the first stage of experimentation, the efficiency and emission characteristics of a diesel engine with a B20 blend of MABD at various fuel injection pressures and fresh air were investigated. During the second phase, fresh air was mixed with 5%, 10%, and 15% exhaust gases, and the experiment was conducted. It was discovered that increasing injection pressure to 230 bar provided considerable improvements. Brake thermal efficiency increased by 2.35%, brake‐specific fuel consumption decreased by 3.57% and pollutants such as carbon monoxide (CO), hydrocarbon, and smoke were reduced by more than 50% compared to conventional diesel. These reductions were similarly significant (over 22%) as compared to the B20 blend at lower injection pressure (210 bar). However, there was a slight trade‐off: nitrogen oxide (NOx) emissions increased partially (3.14%), while exhaust gas temperature (EGT) increased by 1.72% at a higher pressure. The study then investigated the influence of EGR (5%, 10%, and 15%) at various injection pressures. The optimal value seems to be 10% EGR at 230 bar injection pressure. This combination substantially reduced NOx emissions (by over 41% compared to the normal B20 blend) and EGT (by more than 8%), while having no notable effect on other performance or emission variables. Overall, the results show that employing a B20 MABD blend with high injection pressure (230 bar) and moderate EGR (10%) improves engine performance while reducing hazardous emissions. [ABSTRACT FROM AUTHOR]

The improvement in the efficiency of the thermal system can be achieved by disrupting the laminar flow of fluid and boundary layer separators. Passive techniques are already incorporated by industries because it increases heat transfer rate up to many folds. The numerical investigation purpose is to find techniques for heat transfer augmentation in the square duct in the laminar flow regime. The thermo-hydraulic characteristics of ribs and helical screw tape (HST) insert fitted in the square ducts have been presented. The effect of rib orientations on the Nusselt number has been analyzed by the Finite volume-based commercial software ANSYS "Fluent". A SIMPLE algorithm has been used. The fluids having different Prandtl numbers are investigated under an imposed uniform wall heat flux boundary condition. The combination performance is better than the bare and ribbed square ducts. The 45° angled ribs with HST performance is better than the combination of transverse ribs with HST. At Reynolds number 200, the Nusselt number achieved by 45° angled ribs with HST is 4.3% higher than the 30° angled ribs with HST, 22.26% higher than the 60° angled ribs, and 35.82% higher than the transverse ribs with HST. Among the three working fluids, the Nusselt number for Servo-therm oil is the highest because Servo-therm oil minimizes entropy generation. Also, the thermal enhancement factor is greater than one for all considered cases and it is the highest for Servo-therm oil is the highest. [ABSTRACT FROM AUTHOR]

In order to have a heat transfer per volume, heat exchangers have to have high overall heat coefficient. The effects of a transverse wedge on the heat transfer, the pressure drop, and the thermal efficiency factor (TEF) of air flow through a tube bundle heat exchanger was investigated. TEF increases continuously with the wedge aspect ratio (α). Form α = 0.275, 0.550, 0.758 to 1, TEF increases continuously from 1.157 to 1.84, 1.11 to 1.72, 1.05 to 1.42, and 1.02 to 1.39 for x/L = 1/3, 2/3, 1, and 0, respectively. [ABSTRACT FROM AUTHOR]

The investigation of heat transmission and entropy optimization in the thin-film flow of electromagnetic micropolar nanofluids has important implications in industrial lubrications, surgical instruments, and improved cooling systems. The Maxwell–Bruggeman and Krieger–Dougherty models are employed in this study to provide the nanoparticle aggregation/without aggregation attributes affecting the fluid characteristics. The Krieger-Dougherty model examines the modified viscosity caused by concentration of nanoparticle and accumulation, whereas the Maxwell-Bruggeman model assesses the effective thermal conductivity. The flow of micropolar nanofluid is assumed unsteady and laminar. The fundamental equations that govern the flow model are coupled into differential equations by applying appropriate similarity variables. The modeled problem have been solved through the implementation of the Runge–Kutta numerical technique. The findings elucidate that the micropolar effects such as Eringen parameter, spin gradient viscosity, and microrotation have a significant impact on the thin film thermodynamic behavior and flow kinetics. The electromagnetic fields alters the flow and thermal behavior significantly. It has been established that uniform dispersion of nanoparticles is crucial for optimizing thermal efficiency and reducing problems associated with aggregation and without aggregation. It is observed that when agglomeration is considered, the skin friction, entropy and Nusselt number increases significantly. [ABSTRACT FROM AUTHOR]

The present study investigates the significance of the utilization of biodiesel derived from waste cooking oil in diesel engines and its impact on engine output and environmental pollution after blending with diesel and 1-pentanol. The higher values of the ignition index and comprehensive performance index of 4.34 × 10 − 4 mass/min°C2 and 13.71 × 10 − 6 mass2/min2 °C3, respectively, for D70B20P10 (70 % diesel, 20 % biodiesel & 10 % 1-pentanol by volume) indicate superior combustion performance. At full load, carbon monoxide and unburned hydrocarbon emissions from 1-pentanol blended fuels decrease significantly, ranging from 40 % to 52 % and 30.76–46.15 % compared to diesel. The D70B20P10 also showed an improved thermal efficiency of 28.68 % among all tested fuels at full load but slightly lower than diesel (29.56 %). Diesel demonstrated superior in-cylinder pressure (ICP) of 77 bar and heat release rate (HRR) of 41.1 J/ºCA owing to its excellent combustion characteristics. Introducing 5–10 % 1-pentanol in blend improved combustion, elevating ICP and HRR, attributed to enhanced fuel atomization and oxygen content. The sustainable process index value obtained for a global index per person is 0.002 × 10 − 4 cap Litre-1, which lies between 0 and 1, indicates sustainability and compatibility of biodiesel production demonstration by universal biofuels (Andhra Pradesh). [Display omitted] [ABSTRACT FROM AUTHOR]

The present study investigated the performance of dual function reverse flow solar collector (RFSC). The impact of the mass flow rate of air and water on outlet temperature, thermal performance, and overall performance of dual‐function solar air heater (SAH) has also been investigated. An experimental investigation of three different working models namely, Model‐A: SAH, Model‐B: solar water heater (SWH), and Model‐C: integrated solar air‐water heater (SAWH) for dual heating applications was performed to analyze the actual performance of these models. The investigation of the impact of time intervals on the water inlet and outlet temperatures at various mass flow rates of water is conducted to analyze the time‐varying efficiency of SWH systems. Furthermore, the effect of solar intensity on the performance of the dual‐function heating system has also been explained. The result reveals that the maximum thermal efficiency of Models: A and B can be achieved at about 78.8% and 67.9%, at a mass flow rate of 0.0644 and 0.10 kg/s, respectively, according to the experimental findings. The maximum temperature rise of air and water reaches about 52.4 and 55.58°C for Models A and B, respectively. The total efficiency of Model C reaches 81.69%, exceeding that obtained in Models A and B individually. The efficiency, outlet temperature of the fluid, and heat transfer effectiveness of the system strongly depend on the mass flow rate. The increase in heat removal factor is negligible for a higher flow rate (more than 0.10 kg/s). [ABSTRACT FROM AUTHOR]

Researchers demonstrated that implementing new combustion technology and optimising fuel quantity results in a significant reduction in traditional fossil fuel usage and emission levels. The Reactivity Controlled Compression Ignition (RCCI) combustion strategy is one of the low temperature combustion technologies, and it is used to reduce the overall combustion temperature while also providing better combustion control. This study looks into RCCI combustion technology, which uses conventional diesel fuel as the high reactivity fuel (HRF) injected through the injector and acetylene gas as the low reactivity fuel (LRF) injected into the cylinder via a modified inlet manifold alongside air. The modified engine setup was tested for performance, emissions, and combustion under various load conditions, as well as different mass flow rates of acetylene gas, a low reactivity fuel that is injected with air. The flow field of the low reactivity fuel at the inlet manifold is analysed using the Computational Fluid Dynamics principle, which is used to determine the best flow rate for improving combustion quality. According to the simulation results, the optimal acetylene flow rate is 3 Litres Per Minute (LPM), and experimentation shows that at 3 LPM acetylene injection, the brake thermal efficiency (BTE) improves by about 3.2%, and emissions such as carbon monoxide (CO), hydrocarbon (HC), smoke intensity, and oxides of nitrogen (NOx) are reduced by about 35%, 17%, 10%, and 21%, respectively. [ABSTRACT FROM AUTHOR]