This work examines how varying hydrogen addition levels-namely 0% (D100), 10% (D90H10), 20% (D80H20), and 30% (D70H30)-to a premixed diesel-air charge influence combustion behavior and emission formation when tested in a rapid compression machine (RCM). All tests were carried out under conditions of a 423.5 K chamber temperature and a unity equivalence ratio, with the fuel blend being prepared in a premixing chamber prior to its delivery into the combustion chamber. The results indicate that increasing the hydrogen fraction leads to higher in-cylinder pressure and temperature, accompanied by a pronounced shortening of ignition delay. Compared with D100, the D70H30 case shows a 94.85% reduction in ignition delay (1145.88 ms), while the in-cylinder pressure and temperature rise markedly by 108.51% (31.4 bar) and 69.33% (964.93 K), respectively. Regarding emissions, CO levels increased markedly, rising from 0.84 vol% for D100 to 4.35 vol% for D70H30, which corresponds to more than a fivefold increase. In contrast, CO2 shows a pronounced decline as hydrogen content increases, dropping by nearly three times from 9.46 vol% to 3.25 vol%. Meanwhile, unburned hydrocarbons (UHC) emissions also intensify with hydrogen enrichment, with D70H30 exhibiting an increase of 826 ppm, equivalent to a 74.41% rise compared with D100. With increasing hydrogen content, the combustion process accelerates markedly, as evidenced by the reduction in combustion duration from 190 ms for D100 to 77.5 ms for D70H30, representing a shortening of 112.5 ms or 59.21%. Based on the above results, it can be concluded that hydrogen addition has a significant influence on both combustion characteristics and exhaust emissions. These findings deepen the understanding of hydrogen-assisted combustion and establish a useful reference dataset for combustion kinetics and emission analysis in diesel-hydrogen systems, while also supporting the validation of existing kinetic models under RCM conditions. Moreover, the results highlight hydrogen as a practical near-term decarbonization option without requiring major engine design modifications and simultaneously improving ignition behavior. Collectively, this work lays a basis for dual-fuel engine development and for determining appropriate hydrogen blending levels in future applications.

This study experimentally investigates the combined effects of ammonia fraction, equivalence ratio, and swirl intensity on flame stabilization and emission characteristics of premixed CH4/NH3/air combustion in a swirl combustor. Three axial swirlers with vane angles of 30 degrees, 45 degrees, and 60 degrees were employed to vary the swirl intensity. Flame structures were visualized using OH* chemiluminescence imaging, and gaseous emissions (NO, NO2, N2O, CO, CO2, CH4, and NH3) were measured by Fourier-transform infrared (FTIR) spectroscopy. The results indicate that ammonia addition significantly modifies flame anchoring behavior and pollutant formation pathways. At an ammonia fraction of 0.3 at phi = 0.9, NOx emissions exceeded 8000 ppm, reflecting the dominance of fuel-NO formation. Reducing the ammonia fraction to 0.1 and operating under slightly lean conditions (phi approximate to 0.85) led to a significant reduction in NOx emissions from approximately 8000 ppm to below 5000 ppm, while maintaining negligible levels of unburned NH3 and CO. Swirl intensity was found to play a critical role in this balance. Enhanced swirl promoted fuel-air mixing and reduced NOx emissions by up to 69%, whereas excessive swirl at high ammonia fractions resulted in flame instability and incomplete combustion. Among the investigated configurations, the intermediate swirl case (45 degrees vane angle) provided a favorable compromise between flame stabilization and emission control, achieving NOx levels below 2000 ppm while maintaining stable flame operation over a wide range of operating conditions. These results highlight the importance of coordinated control of equivalence ratio, ammonia fraction, and swirl intensity in swirl-stabilized ammonia-methane combustors and provide practical insights for the development of low-emission combustion systems for energy applications. The novelty of this study lies in the systematic investigation of the coupled effects of swirl intensity, fuel composition, and equivalence ratio on flame behavior and emissions in ammonia-methane combustion.

Amonijak privlači pažnju kao perspektivno alternativno gorivo zbog svog sastava bez ugljenika i potencijala za smanjenje štetnih emisija. Ova studija istražuje uticaj amonijaka, koji se koristi kao dvostruko gorivo sa dizelom pri koncentraciji energije amonijaka od 10% ili manje, na sagorevanje, performanse i emisije stacionarnog jednocilindričnog motora sa kompresionim paljenjem, koristeći AVL BOOST simulacioni model. Motor RV-125, popularan model za ruralna područja u Vijetnamu, projektovan je da radi u opsegu brzina od 900 do 2400 o/min pri opterećenju motora od 85%, sa tri različita trajanja sagorevanja: 80, 100 i 120 stepeni ugla radilice (CD80, CD100 i CD120). Rezultati pokazuju da povećanje sadržaja amonijaka na 10% energije goriva neznatno poboljšava snagu motora za približno 1%, ali takođe dovodi do veće potrošnje goriva specifične za kočenje zbog niže gustine energije amonijaka. Kada je amonijak prisutan u smeši, vrhovi brzine oslobađanja toplote (HRR) i pritiska u cilindru se blago povećavaju na CD80, ali se blago smanjuju na CD100 i CD120; u međuvremenu, utvrđeno je da vrh temperature u cilindru postepeno opada sa dužim vrednostima CD, a vremena vrhova HRR, pritiska u cilindru i temperature su blago usporena. Rezultati takođe pokazuju da mešanje amonijaka značajno smanjuje emisije NOx za više od 22% i emisije CO za približno 27%, dok emisije čađi ostaju praktično nepromenjene. Studija zaključuje da mešanje amonijaka predstavlja obećavajuću alternativu za ublažavanje štetnih zagađivača i emisija gasova staklene bašte bez ugrožavanja snage ili efikasnosti motora. Ovaj rad pruža ključnu osnovu za buduća istraživanja usmerena na primenu amonijačnog goriva za ruralni razvoj u Vijetnamu.

This study proposes a novel contraction duct structure outside the cold-side heat exchanger (CHE) of a motorcycle exhaust thermoelectric generator unit (TGU) and investigates the effects of its parameters-contraction profile order, inlet, Hi, and outlet height, Ho-on the TGU's output power and thermal uniformity. These parameters influence the outside air velocity distribution along the CHE, impacting the heat transfer capacity and temperature distribution, ultimately affecting output power and thermal uniformity. The results indicate that increasing contraction profile order (i.e., steeper profile) increases output power, while its effect on thermal uniformity varies depending on Hi. An increase in Hi enhances both these characteristics, whereas an increase in Ho reduces both. Ho presents the most significant effect, followed by Hi, and the contraction profile order. In this case study, two optimal parameter sets are the 7th order polynomial profile and the symmetric matched cubic profile with Hi = 240 mm and Ho = 60 mm, improving 1.15 and 1.20% in output power and 13.78 and 13.53% in thermal uniformity at 50 km/h motorcycle speed. This research elucidates the significant impact of the contraction duct on TGU performance, demonstrating that this simple structural modification can effectively enhance both the TGU's power and uniformity. The findings provide a valuable foundation for the optimal design of TGUs, which is essential for advancing their application in recovering engine exhaust heat.

In this study, a rapid compression machine (RCM) was used to study the traditional JP-5 fuel and the JP-5 surrogate. In the experiment, the ignition delay characteristics with low-to-intermediate temperature compression temperatures ranging from 675 to 800 K, compression pressures of 10, 15 and 20 bar, and equivalence ratios of 0.25 and 0.37 are discussed. Among them, the auto-ignition delay time of JP-5 and the surrogate all shorten the ignition delay time as the compression pressure and equivalence ratio increases, where the negative temperature coefficient (NTC) phenomenon begins to occur at temperatures of approximately 732–746 K. It is worth noting that an increase in pressure or the equivalence ratio of the two fuels changes their low-temperature oxidation reaction pathway, thereby increasing the initial temperature of the NTC. The two fuels showed similar ignition characteristics in the measured temperature range. The difference between the two fuels was approximately 6.18

This study presents an optimal design process for the muffler geometry to reduce the pressure drop of a motorcycle thermoelectric generator system by applying elliptical and contraction profiles. The elliptical profile is used at the junction between the front wall of the muffler and the inlet pipe as well as between the outlet pipe and the rear wall, with optimized semi-major axes, b and e, respectively. Two profiles are applied and compared at the junction between the front wall and muffler body, containing an elliptical profile with optimal semi-major axis, c, and contraction with optimal polynomial order, P-i. Finally, the contraction profiles are selected to be used at the junction between the rear wall and the muffler body, P-o. The results reveal that these profiles reduce the impact of sudden cross-sectional changes and diminish vortex formation, thus decreasing local pressure drop at the applied locations and contributing significantly to the overall pressure drop reduction of the thermoelectric generator system. Besides, the effects of optimal elliptical profiles at the inlet and outlet are more substantial than those of the optimal contraction profiles at the muffler body. The optimal parameters, b = 20mm, third-order polynomial P-i, e = 20mm, fifth-order polynomial P-o, reduce pressure drop by 43% compared to the original and nearly 8% compared to the previous. This study contributes an optimal design process to reduce pressure drop for motorcycle thermoelectric generator systems by practically applying high-efficiency aerodynamic profiles, thereby providing a foundation for designing, manufacturing, and commercializing the system.

The study employs AVL Boost software to investigate the effects of different methanol blending ratios (BR) in diesel-methanol mixtures (ranging from 0 to 50%), ignition timings (IT), and combustion durations (CD) on the power and brake specific fuel consumption (BSFC) of a single-cylinder diesel engine under various loads of 85, 70, and 50%. Throughout this study, the term IT refers to the start of combustion of diesel fuel in the combustion chamber. The simulation model is validated by comparing the power and torque simulated results and experimental data, with the discrepancy less than 5%. The optimal ITs for maximum power and minimum BSFC are identified, then predictive models are developed based on these optimal IT values as functions of BR at various engine loads and CDs. The results show that the correlations between the IT, BR, CD, and engine load are linear functions. The ITs that simultaneously deliver peak power output and the lowest BSFC are governed primarily by CD, with the BR exerting a secondary effect; whereas, engine load plays a comparatively minor role. For maximum power, the largest variations in optimal ITs are approximately 15oCA for CD, 5oCA for BR, and 4oCA for load. For minimum BSFC, the corresponding maximum differences are about 15, 5, and 3oCA for CD, BR, and engine load, respectively. Optimal IT prediction models have been established that can minimize the time and cost associated with engine experimental tests to obtain the lowest BSFC and highest engine power at various CDs, engine loads, and methanol BRs.

Thermoelectric material properties are crucial for simulating thermoelectric modules (TEMs); yet, determining them requires complex and costly experiments due to temperature-dependent behavior and parasitic losses. This work proposes an approach for estimating TEM's equivalent properties from its output characteristics using thermal resistance (TRM) and numerical simulation modeling (NSM) accessibly, cost-effectively, and time-efficiently. Sensitivity analysis and cross-module validation confirm the method's reliability. The obtained equivalent property sets enable accurate prediction of TEM's output characteristics for the TRM and NSM compared with manufacturer data, with deviations of open-circuit voltage, maximum power, and conversion rate of 0.87%, 2.53%, and 3.07% for TRM, and 0.91%, 2.51%, and 3.24% for NSM, respectively. This finding implies that a TRM of TEMs can replace NSM in large-scale simulations, saving resources while ensuring accuracy. The proposed approach makes determining TEM properties less challenging; also, the equivalent properties reduce computational efforts required for simulating the thermoelectric generator system characteristics.

Effective thermal management ensures safe operation and improves battery packs' energy efficiency and longevity in electric vehicles (EVs). This computational fluid dynamics study investigates the thermal performance of a lithium-ion battery pack used for the two-wheeled EV under its two practical conditions on the road and four different environmental temperatures. Seven models were proposed for structural optimization to improve the heat transfer capacity of the battery pack. The Taguchi method was employed to consider the influence level of key factors on battery pack temperature, including environmental temperature, vehicle operating condition, cap and case material, and structural parameters of a fixing rib on the cap. The results show that all proposed structural models considerably enhance the heat transfer, maintaining the mean cell temperatures below the operational limit of 60 degrees C, and reducing the average cell temperature up to 13 degrees C (about 23.24%) compared with the original model. The battery pack's cap and case material strongly impact its heat dissipation, so it should be prioritized for studies to improve the thermal management of the battery. This work serves as a reference for similar thermal management research to improve battery pack lifespan and efficiency, particularly on low-power EVs.

This study investigates the effects of magnetic field intensity on the combustion characteristics and emissions of methane-air mixtures in an optical constant volume combustion chamber (CVCC). Experiments were conducted at five air-fuel ratios (AFRs = 10, 11, 12, 13, and 14) under three magnetic field conditions: 0 Gauss (NG), 7000 Gauss (NGM-1), and 9000 Gauss (NGM-2). Results show that the application of a magnetic field enhances combustion pressure and accelerates flame propagation. At AFR = 11, the peak pressure increased by 1.024 bar under NGM-2 compared to NG, and the time to peak pressure was shortened by 59.02 ms. Emission analysis revealed significant reductions in hydrocarbon (HC) and nitric oxide (NO) emissions, with HC reduced by up to 95.35% and NO by 45.57% under magnetized conditions. Although changes in CO and CO2 emissions were modest (maximum variations of 0.08% and 0.73%, respectively), combustion completeness improved with increasing magnetic intensity. The unstretched laminar flame speed increased from 15.58 cm/s (NG) to 22.1 cm/ s (NGM-2) at AFR = 13, corresponding to an 88.73% relative increase at AFR = 14. High-speed flame imaging confirmed faster and more luminous flame propagation under stronger magnetic fields. These findings provide systematic experimental evidence that externally applied magnetic fields can accelerate flame development and improve combustion completeness in methane-air mixtures. The demonstrated reductions in HC and NO emissions, together with the pronounced enhancement of laminar flame speed under lean-burn conditions, highlight the novel role of magnetic pre-conditioning as a previously unexplored strategy to control combustion dynamics. The results indicate a promising potential for magnetic assistance in lean methane combustion, which may help improve flame development and combustion completeness under the conditions investigated.

This study investigates the impact of cold air inlet duct positions and their flow rates on the temperature distribution inside the refrigerated container. Computational fluid dynamics simulations are combined with response surface methodology to examine and optimize temperature uniformity in the container environment. Central composite design is applied to optimize the simulation samples with twenty-nine cases. A second-order temperature difference prediction model with four variables, including two inlet duct position parameters and two flow rate parameters, is developed and validated through analysis of variance, showing strong statistical significance with a coefficient of determination R² of 0.95. The results show that the identified optimal configuration has a container temperature difference of 2.09 K, substantially improving temperature uniformity by 40% compared to the conventional model. Ten optimal cases of temperature difference are selected based on the desirability functions to conduct simulations and compare with the predicted values ​​from the regression model, resulting in an average relative error of 3.37%. The current work contributes to more economical and environmentally friendly frozen transportation options by enhancing temperature uniformity within the container, thereby enabling the potential to reduce energy demand for refrigeration and lower CO2 emissions. Additionally, the proposed approach maintains high prediction accuracy while improving overall optimization for refrigeration containers.

This work examines the influence of key structural parameters—the first-stage gear ratio, the gear module, and the number of teeth on the driving gears—on the total gear weight of a two-stage reduction gearbox for electric vehicles. An analytical model relating these parameters to the gear geometry, the contact and tooth-root strength, and the resulting mass is first established and implemented in Microsoft Excel; analysis of variance is then applied to quantify the relative contribution of each factor. The results indicate that the gear-ratio distribution has the greatest influence, accounting for 77.41% of the variation, with lower first-stage ratios and higher second -stage ratios generally reducing gear weight. The number of teeth on the second-stage driving gear has a greater effect (18.64%) than that on the first-stage driving gear (2.95%), and the overall gear weight reduces as the number of teeth goes up. The gear module produces a complex yet minor net effect (0.03%), increasing or decreasing the gear weight depending on whether the configuration has fewer or more teeth. The lightest (minimal) configuration—a first-stage gear ratio of 2.259, a module of 4 mm, and 27 teeth on both the first and second-stage driving gears—weighs 5.15 kg, which is 42.66% lighter than the heaviest (maximum) configuration—a first-stage gear ratio of 4, a module of 4 mm, and 17 teeth on both driving gears—weighing 8.98 kg. The work provides an innovative approach to multiparameter optimization for the design of lightweight two-stage electric-vehicle gearboxes.

Accurate yet computationally efficient multiphysics modeling of thermoelectric generator systems for internal combustion engine waste heat recovery remains challenging due to the strong coupling between fluid flow, heat transfer, and thermoelectric conversion. This study develops three improved multiphysics fluid-thermal-electric modeling approaches, including a two-way coupled computational fluid dynamics-thermal-electric model (CFD-TE(SC)), a two-way coupled CFD-thermal resistance model (CFD-TR(UDF)), and a simplified one-way coupled CFD(sim)-TR model, which are systematically compared under various operating conditions. The results show strong agreement in predicting overall thermal and electrical characteristics of three models, particularly around the maximum power operating point, while also revealing the impact of thermoelectric effects on system energy balance. The CFD-TE(SC) model provides the most physically complete results by fully coupling the fluid-thermal with thermal-electric fields, enabling comprehensive analysis of TGS characteristics. The CFD-TR(UDF) model achieves high accuracy in predicting system-level performance, with negligible deviations in output power, heat absorption, TEM temperature gradient, and temperature non-uniformity from CFD-TE(SC) of 1.93, 0.43, 0.46, and 1.38%, respectively, while significantly reducing simulation time and resources through an improved coupling strategy. Moreover, its deviations are insensitive to exhaust mass flow rate and temperature. Conversely, the CFD(sim)-TR model offers advantages in simplicity and computational efficiency while maintaining good consistency around the maximum power points by employing an appropriate TEM's equivalent thermal conductivity; however, its deviations increase considerably away from this region. Over the entire operating range, the corresponding average deviations are 8.71, 3.40, 5.00, and 3.75%, respectively. Additionally, exhaust temperature substantially affects deviations of this model, while the impact of mass flow rate is relatively small. This work clarifies principles and trade-offs among modeling completeness, accuracy, and computational efficiency in multiphysics approaches for TGS, thereby providing practical guidance for selecting appropriate modeling approaches based on specific analysis objectives in TGS design and optimization.

In this study, the effects of different lifting cylinder diameters of 40mm, 50mm, 63mm, and 80mm, which are called Model I, Model II, Model III, and Model IV, respectively, on the kinematics, dynamics, and overall performance of the bin lifting-flipping mechanism of a garbage truck were investigated using numerical methods. Verification of the simulation results demonstrated high consistency with the analysis calculation. The results show that increasing the lifting cylinder diameter reduces its working pressure and velocity, increases its peak force, and the system consumes more energy. The lifting mechanism is mechanically suspended on the flipping mechanism and also connected via sequence valves. Therefore, stability is constantly enhanced through Models I, II, and III by reducing the sequence valve partial opening and the lifting mechanism stoppage inertia. However, Model IV is unstable in the lifting process because of the extreme lifting cylinder's peak force. That force magnitude is also the reaction on the flipping mechanism, which leads to the formation of double oscillation. The energy consumption difference is insignificant, at only 2.3% between the least and most energy-consuming models. Model III is proposed as the overall well-performing model with stability in both the lifting and flipping processes. It generates 37.8%, 11.9%, and 73.9% less maximum lifting cylinder force, maximum flipping cylinder force, and force at the revolute joint, respectively, than the worst model for each considered aspect. This work provides a reference for designing and optimizing the parameters of mechanical-hydraulic systems to enhance stability, operating performance, and reduce dynamic loads.

This study investigates various hot-side heat exchanger (HHE) structures within motorcycle exhaust thermoelectric generator systems (TGS). Models including trapezoid, rectangular, accordion, serial-plate, incline-plate, and finless nonuniform rational B-splines (NURBS) were scaled in the same size and evaluated under identical conditions of similar mufflers. The HHE's impacts on TGS's output power, thermal uniformity, and pressure drop were assessed through computational fluid dynamics simulations. Results indicate that rectangle and NURBS models yield the highest output power but poor thermal uniformity; rectangle provides the highest output power, while NURBS has the lowest thermal uniformity. Conversely, incline-plate and serial-plate offered substantial thermal uniformity but lower power. The trapezoid and accordion provide dramatic output power while maintaining high thermal uniformity, with the trapezoid excelling in thermal uniformity. Besides the significantly higher pressure drop of serial-plate, other models' pressure drops are equivalent. This comparison suggests that the trapezoid and accordion models are promising for TGS design and optimization.

Liquefied petroleum gas (LPG) is considered one of the alternative fuels used in engines to solve the energy security problem and mitigate environmental pollution. This study investigates the combustion, performance, and emissions of diesel-LPG blends, with different LPG concentrations from 0 to 50 %, in a stationary diesel engine using AVL Boost software. Combustion parameters such as combustion duration, start of combustion, and Vibe function shape factor were adjusted, based on experimental research results, to vary with the LPG concentration in the blend to simulate the combustion process more closely to reality. The results indicate the 70 % diesel-30 % LPG blend (D70L30) improves engine torque, power, and specific fuel consumption by up to 5.60, 8.45, and 6.90 %, respectively. The peaks of in-cylinder pressure, temperature, and heat release rate are improved by up to 32.62, 7.04, and 35.02 %, respectively, at the 50 % diesel-50 % LPG blend (D50L50). As the LPG concentration in the blend increases, NOx tends to increase while soot and CO decrease. The D50L50 blend produces 130.62 % more NOx than diesel; at the same time, it also produces 66.36 and 25.37 % less soot and CO than its counterpart, respectively. These findings suggest the D70L30 is the optimal diesel-LPG blend, achieving improvements in engine performance while balancing the trade-off-based emissions between NOx, soot, and CO. This study adds valuable insights to the refinement of AVL Boost simulation approaches. In addition, the current work is significant in contributing to the research, development, and application of alternative fuels for sustainable rural development in Vietnam.

The depletion of fossil fuel supplies and the harmful environmental effects of combustion have emerged as significant issues. One viable approach to address these challenges is optimizing fuel injection timing to improve diesel engine performance. This work studies the effects of ignition timing (IT) and premixed ratio (PR) on the performance of a diesel engine at various combustion durations (CDs) and engine loads using the Multiple Vibe 2-Zone model of the AVL BOOST program. The predictive models of optimal ITs according to CD, PR, and engine load were established based on the engine's maximum power and minimum brake-specific fuel consumption. The findings show that optimal IT and CD correlations are linear at every PR and engine load. The optimal IT rises with increasing CD and reducing PR and engine load. CD has the most significant effect on optimal IT, followed by PR, and engine load has the least influence. The largest differences in optimal IT for the maximum torque and power are 1.0, 2.3, and 11.1 crank angle degrees when changing the engine load, PR, and CD, respectively. Meanwhile, for the optimum IT to achieve minimum brake-specific fuel consumption, those corresponding values are 1.0, 2.0, and 11.0 crank angle degrees. This study aids in lowering the resources, time, and cost needed to conduct experiments to determine the ideal injection timing of the engine.

This work investigates the temperature distributions in a refrigerated truck container using three typical arrangement methods of cargo boxes, including the centerline, offset, and pinwheel. The effects of parameters, such as the gap between cargo boxes and the container floor, the lateral gap between cargo boxes, the longitudinal gap between cargo boxes, and the gaps between the cargo boxes and the side wall and front wall, are analyzed by the computational fluid dynamics approach in each cargo arrangement method. The results indicate that the layout parameters considerably affect the temperature distributions for centerline and offset methods, while their effects are insignificant for pinwheel methods. The set of optimal layout parameters reducing the temperature differences of 3.5, 6.5, and 1 K for the centerline, offset, and pinwheel arrangement methods correspond to temperature uniformity improvements of up to 50, 65, and 12 %, respectively. The centerline method achieves the most temperature uniformity due to enhanced airflow across cargo gaps, reducing stagnant zones and minimizing temperature differences. The offset approach does not indicate the more considerable decrement of the stagnant zone, as revealed in the centerline one. The pinwheel method showed limited improvement due to the restricted airflow at the container rear. This study offers an optimized cargo arrangement strategy to enhance temperature uniformity, conserve energy in refrigerated containers, and ultimately improve the quality of the product while minimizing operating costs and environmental impact.

The generation of a recirculation zone in jet flow has recently been demonstrated to influence flame stability and soot formation. In this study, we conducted both experiments and numerical simulations to elucidate the mechanisms underlying vortex formation in laminar coflow diffusion flames. Numerical models were developed by incorporating various parameters, including fuel density, jet velocity, fuel temperature, and ambient air temperature. The flow patterns near the nozzle indicated how these parameters affect the development of the recirculation zone. Simulation results were validated against experimental data. Among the studied parameters, fuel density, jet velocity, and nozzle diameter emerged as the primary factors influencing recirculation flow, whereas fuel and ambient air temperatures exerted secondary effects. Detailed analysis of each parameter unveiled critical conditions at which the recirculation zone forms.

This paper presents research on raising the efficiency and pressure of centrifugal fans at different speed ranges. This problem is related to the incompatibility of the fan characteristics with the speed conditions of the impeller and flow conditions of the installation when the centrifugal fans are operated, which decreases efficiency and raises energy consumption. In this research, a novel concept of regulating the blade parameters of centrifugal fans was given. The basis of this study is that a change in the blade angles and impeller outer diameter at different speeds significantly affects the power and the pressure rise of the fan. The scientific basis of this idea, which is using flexible blades for the fan, is aimed at providing high flow rates at relatively low running speeds, relatively low power requirements, and high efficiency when the fan operates in high-speed regions. Therefore, the design of the fan uses variable angles of the impeller blades by linking each blade to two springs. It enables adjustment to change the inlet and outlet blade angle of the impeller, which allows extending the range of operating parameters in accordance with the impeller speed. The flow simulation tests (CFD) of the novel method demonstrated the feasibility of adjusting the blade parameters and confirmed the benefits of this solution. The results of the research are given on the basis of the numerical analysis method and statistical computation method.