Optimum Inclination Angle Research Articles

Superhydrophobicity induced antibacterial adhesion and durability of laser bidirectionally-textured zirconia surfaces with different inclination angles

Femtosecond laser bidirectional texturing with different laser energy densities and inclination angles was performed on zirconia (ZrO2) surfaces. The laser bidirectional texturing models under different inclination angles were constructed to predict the water contact angles (WCAs), and the superhydrophobicity induced antibacterial adhesion mechanism was analyzed. The results revealed that under the combined effect of the optimal laser energy density (7.0 J/cm2) and inclination angle (90°), the laser-textured ZrO2 surface could obtain a micro-nano dual-scale structure composed of periodic regular micro-cones and nanoparticles. This structure not only promoted the adsorption of carbon-containing hydrophobic groups from the stearic acid and the air to form a superhydrophobic surface with excellent chemical/mechanical durability and anti-fouling/self-cleaning abilities, but also minimized the contact area with the bacterial suspension (solid/liquid contact area ratio of 6 %) to enhance antibacterial ability. The optimal stearic acid-modified laser-textured ZrO2 surface exhibited an extremely low adhesive force (Fadhesive=6.69 μN) to the bacterial suspension, and thus achieved the highest antibacterial ratio of 85.3 %. This study is expected to enrich the application of ZrO2 ceramics in the medical field.

Opracowanie konstrukcji świdra wiertniczego do zwiercania skał o różnych właściwościach mechanicznych

This paper presents a description of a bit design with a combined cutter layout, aimed at increasing the efficiency of breaking rocks with different mechanical properties. The results from industrial testing of the manufactured bits are analyzed, revealing the need to improve their hydraulic flushing system. Computer modeling was conducted using the Flow Simulation CAD/CAM package of the Solid Works system, where various models of the design options for the bit, the borehole bottom, and a segment of the drill string were created. For each variant, numerical calculations of the fluid motion were carried out using the finite element method. Based on the simulation results, optimal angles of inclination for the jet nozzles relative to the bit axis and their distance from this axis were determined. Key factors influencing the stability of the bit cutters, which destroy the rock by cutting with axial vibrations, were identified, and analytical dependencies for their predictive stability were derived. The wear rate of the bit cutters was determined by instantaneous values of such physical parameters as: the degree of wear, rock cutting speed, temperature, axial loading force on the cutter, and the friction coefficient at the contact between the cutter and rock. Temperature is especially impactful, reaching levels exceeding 1000°C in the cutting zone; it is often regarded as the primary factor influencing bit cutter stability. To maximize the efficiency of rock-breaking in the process of drilling wells, it is necessary to set the following vibration parameters: frequency, amplitude, and vibration mode, which can be determined from the results of mathematical modeling.

NUMERICAL SIMULATION AND OPTIMIZATION OF THE POTATO HARVESTER DIGGING SHOVEL IN HILLY AREAS

The shovel face inclination angle is a crucial parameter of the potato harvester digging shovel. Currently, there is limited research on the relationship between the inclination angles of curved digging shovel surfaces. The purpose of this study was to investigate the impact of the shovel face inclination angle on its soil crushing capacity in hilly terrain. A simulation model for the contact between the digging shovel and the soil was developed. The digging process of the shovel was simulated and analyzed under different shovel face inclination angles (α2). The analysis included comparisons of stress, Plastic Equivalent Strain (PEEQ), and energy. The results show that the larger the angle, the stronger its soil crushing ability; however, if the angle difference is too large, the phenomenon of soil flipping back occurs. When α2 = 16–17 °, the shovel length becomes excessive. When α2 = 18 °, the stress is too small. When α2 = 19 °, the energy is too large, and when α2 = 23–24 °, the PEEQ is too small. Therefore, the optimal shovel face inclination angle α2 is between 20 and 22 °, with fixed angles α1 = 15 ° and α3 = 13 °.

Heat transfer performance of a multiport mini-channel loop thermosyphon for cooling miniaturized electronic devices

Multiport mini-channel thermosyphon with hydraulic diameters less than 2 mm undergoes a severe entrainment problem both in vapor and liquid regions, impeding the flow and affecting the performance characteristics. To address this issue, a novel multiport mini-channel loop thermosyphon (MPMC-LT) design is proposed. This design separates the vapor and liquid flow paths, reducing entrainment and enhancing the performance characteristics. Tests are conducted with heat loads ranging from 5 to 45W at four inclinations (0°, 30°, 60°, and 90°) relative to the horizontal plane. Results revealed that the MPMC-LT design extends the entrainment limit by 10.6 times compared to conventional designs, reducing the interaction between the vapor and condensed working fluid. Additionally, the total entropy and thermal resistance drops by 20.7 % and 19.9 %, respectively at an optimum inclination angle of 30°. It is also noted that the effective thermal conductivity at the optimal inclination is 5.8 times higher compared to the conventional multiport thermosyphon designs. The design effectivity uses the buoyancy, inertial and surface tension forces to reduce resistance in the fluid flow, thereby enhancing the heat transfer characteristics. These results highlight that MPMC-LT is a suitable thermal management device for power electronic systems.

Thermo-hydrodynamic characterization and mapping of the two-phase flow in a capillary tube

The study presents an experimental investigation on the behavior of condensate film and liquid–vapor meniscus in the unit cell of a pulsating heat pipe (PHP) at different operating boundary conditions, and their respective roles in determining PHP’s performance. The orientation and the temperatures of evaporator and condenser sections are taken as the variable operating boundary conditions whereas the amplitude of oscillations influences the performance of the PHP. The entire thermo-hydrodynamic phenomenon is captured using high-speed imaging. By tracking the interface of liquid film and vapor, different regimes for film flow in the condenser section are observed and characterized. Also, the oscillation amplitude has been quantified at different operating boundary conditions. Despite a quite small tube diameter, gravity plays a key role in determining the liquid and vapor phase distributions in the tube. The variation of oscillation amplitude is intimately linked with the nuances of film flow regimes and inter-regime transitions. The optimum inclination angle, and evaporator and condenser temperatures are found to exist for the PHP unit cell which maximize the oscillation amplitude. The dependence of optimum inclination angle on condenser temperature has also been understood along with. Further, the associated film flow regime in condenser which facilitates these optima has also been recognized. All variable operating boundary conditions are observed to have a peculiarly mixed influence on the flow regimes and thus oscillation amplitude. The study would help to achieve a better elementary understanding of the role of condensate film flow in determining PHP’s performance and develop a flow regime map particularly for PHPs.

Impact of Rear Slope Variation on Rubble Mound Breakwater Stability Under Seismic Loading

This study aims to enhance the seismic stability of rubble mound breakwaters, crucial maritime structures, by examining how variations in the rear slope angle affect their response to seismic loads. Utilizing the Plaxis 2D software, a finite element method was employed to simulate the behavior of a conventional rubble mound breakwater under different seismic conditions. The analysis considered three different rear slope angles and subjected each to various seismic loads characterized by differing amplitudes and frequencies. Our findings indicate that the rear slope inclination significantly influences the seismic response of the breakwaters, notably affecting the displacements and deformations within the structure. The most optimal angle of inclination was identified, which minimized the seismic-induced deformations, thereby potentially improving the structural integrity and longevity of these maritime defenses. This investigation not only provides valuable insights into the design of more resilient maritime structures but also introduces an approach to optimize breakwater design for better performance under seismic conditions, marking a notable improvement in the field of maritime engineering. Doi: 10.28991/CEJ-SP2024-010-08 Full Text: PDF

Orbit design for a future geodetic satellite and gravity field recovery

Spherical geodetic satellites tracked by satellite laser ranging (SLR) stations provide indispensable scientific products that cannot be replaced by other sources. For studying the time-variable gravity field, two low-degree coefficients C20 and C30 derived from GRACE and GRACE Follow-On missions are replaced by the values derived from SLR tracking of geodetic satellites, such as LAGEOS-1/2, LARES-1/2, Starlette, Stella, and Ajisai. The subset of these satellites is used to derive the geocenter motion which is fundamental in the realization of the origin of the terrestrial reference frames. LAGEOS satellites provide the most accurate standard gravitational product GM of the Earth. In this study, we use the Kaula theorem of gravitational perturbations to find the best possible satellite height, inclination, and eccentricity for a future geodetic satellite to maximize orbit sensitivity in terms of the recovery of low-degree gravity field coefficients, geocenter, and GM. We also derive the common station-satellite visibility-coverability coefficient as a function of the inclination angle and satellite height. We found that the best inclination for a future geodetic satellite is 35°–45° or 135°–145° with a height of about 1500–1700 km to support future GRACE/MAGIC missions with C20 and C30. For a better geocenter recovery and derivation of the standard gravitational product, the preferable height is 2300–3500 km. Unfortunately, none of the existing geodetic satellites has the optimum height and inclination angle for deriving GM, geocenter, and C20 because there are no spherical geodetic satellites at the heights between 1500 (Ajisai and LARES-1) and 5800 km (LAGEOS-1/2, LARES-2).

CFD and RSM Assist in Reducing the LPG Consumption of Burners for Agarwood Oil Production in Thailand

ABSTRACT This research aimed to optimize LPG consumption in Thai commercial burners used in agarwood oil production, specifically focusing on the KB-10, S-10, and EB-10 burners. Enhancing burner efficiency is crucial due to rising energy costs and environmental concerns. A dual approach using Response Surface Methodology (RSM) and Computational Fluid Dynamics (CFD) was employed in order to achieve the best burner. Central Composite Design (CCD) within the RSM framework determined the optimal swirl and inclination angles combinations. Modified burners with variant combination angles, as suggested by RSM, were numerically investigated. CFD simulations with Ansys Fluent, utilizing the k-ε turbulence and discrete ordinates (DO) radiation models, provided detailed insights into the combustion and heat transfer processes of those modified burners. The modified burners, SB10–1, SS10–3, and SEB10–7, demonstrated significant improvements. Laboratory and field tests indicated energy savings of 16.15%, 23.74%, and 20.75%, respectively. Statistical analysis confirmed these savings with p-values < .05. The 95% confidence intervals for LPG savings were 31.31 ± 0.8%, 33.42 ± 0.7%, and 31.84 ± 0.6%, corresponding to payback periods of approximately 2.99, 4.21, and 8.95 months. Additionally, CO and NOx emissions were kept below 350 ppm and 100 ppm, respectively. The novelty of this study lies in the combined use of RSM and CFD to optimize burner performance, leading to significant energy savings and emission reductions. These findings highlight the potential of these methods for burner optimization, offering both economic and environmental benefits. This research underscores the importance of integrating advanced modeling techniques to achieve sustainable and cost-effective industrial processes.

DETERMINATION OF THE OPTIMAL INCLINATION ANGLE OF THE TRUSS FILLER IN A DOUBLE-WALLED TANK

The paper considers the application of the tank wall design, which is a three-layer panel consisting of two shells, between which there is a truss filler. Such a filler is a repeating spatial structure consisting of pyramids or tetrahedrons.The analysis of references concerning such a construction is carried out. As a result of the analysis, it was revealed that the three-layer panel with a truss filler found its application in aviation and rocket engineering, and all studies were carried out for structures with thickness not exceeding 150 mm, and the applied load was evenly distributed over all surfaces.To research the stress-strain state of the tank structure, two numerical models were created in the SCAD Office software package. All active loads are collected. The calculation was carried out for tank structures, in the inter-wall space of which pyramids and tetrahedrons were located.The technology used relates to cross-cutting digital, namely digital design and modeling, which is currently included in the concept of technological development of our country.The search for the optimal inclination angle of the rods was carried out in the range from 40° to 60°. Five calculations were performed for each placeholder in the corresponding ranges.As a result of geometric parameters dependencies researches of the double-walled tank wall, the inclination optimal angles values of the pyramidal and tetradrael rods fillers for the wall of a tank of 50000 m3volume were obtained. There are obtained dependences to determine the optimal inclination angle of the rods of the truss filler for a tank of any volume, using relative values, as well as the values of forces arising in the rods of the filler depending on the hydrostatic column of the liquid.

Angle-of-attack characteristics of opposing jet for improving drag and heat reduction

While the opposing jet technique has the potential to achieve efficient drag and heat reduction, it can be severely affected by the incoming angle of attack. To analyze the angle-of-attack characteristics of opposing jet for improving drag and heat reduction, a three-dimensional blunt model was studied under various jet stagnation pressure ratios and angles of attack using the verified numerical method. The results showed that the enhanced reattachment shock on the windward side resulted in a higher pressure and temperature rise, which led to the deterioration of drag and heat reduction. Under the influence of the incoming angle of attack, the recirculation vortex transformed into a longitudinal vortex, resulting in a slanted U-shaped distribution of the surface pressure coefficient and Stanton number. Increasing the jet stagnation pressure ratio widened the coverage of the recirculation vortex on both the windward and leeward sides, which brought an improvement in drag and heat reduction. The interaction between the incoming angle of attack and the opposing jet caused a double-peak distribution of Stanton number due to the recirculation vortex reattachment and the compression of the incoming flow. The inclined opposing jet could reduce the peak values of pressure coefficient and Stanton number when subjected to the incoming flow with an angle of attack by spreading the recirculation vortex along the windward side. There should exist an optimal inclination angle that can effectively reduce the peak caused by the compression of the incoming flow without generating an excessive peak due to the recirculation vortex reattachment.

Research on erosion wear law of four-way flow channel of wellhead fracturing in ultra-deep wells

Abstract This paper establishes a 1/2 three-dimensional finite element model that considers multiple factors affecting the erosion rate of the four-way fracturing structure on site. The model can simulate the effects of different inlet velocities, dynamic viscosities, outlet quantities, outlet pressures, and channel wall angles on the velocity and streamline distribution of the four-way channel. It is also possible to analyze the effects of different factors such as inlet velocity, sand carrying mass flow rate, inlet quantity, fluid dynamic viscosity, fracturing fluid particle density, fracturing fluid particle diameter, four-way wall hardness, and channel wall inclination angle on the erosion of the inner wall. Through the established model calculation, it was found that as the inlet flow velocity increases, the maximum flow velocity in the channel also increases, and the value is close to 1.8 times the inlet velocity, with the maximum value appearing at the inlet corner. When the inlet velocity of the four-way valve is low, a significant vortex-like flow field appears in the closed flow channel of the four-way valve, which will lead to the accumulation of particles in the fracturing fluid. The calculation shows that the number and velocity of sand containing fracturing fluid inlets have the greatest impact on the erosion rate of the four-way flow channel, and the optimal inclination angle of the flow channel is 9 degrees. Increasing the hardness of the four-way wall can improve the maximum erosion rate of the flow channel wall, but changing the sand particle density and diameter has little significance in reducing the erosion rate of the four-way flow channel. It is recommended to perform corresponding heat treatment on the inner wall of the four-way valve to reduce the impact of sand containing fracturing fluid on wall erosion. This article provides a theoretical basis and guidance for controlling or avoiding erosion and thinning failure of four-way valves and also provides a theoretical basis for the design of wellhead four-way valves and various safe construction operations.

Effects of inclination angle and fluid parameters on binary fluid convection in a tilted rectangular cavity

Thermal convection of binary fluid mixtures with negative separation ratios in a tilted rectangular cavity heated from below is numerically investigated using a high-accuracy finite-difference method. The fluids under consideration are Newtonian fluids with the Prandtl number (Pr) and Lewis number (Le) in the ranges of 0.01≤Pr≤10 and 0.001≤Le≤1, respectively. Extensive direct numerical simulations are conducted to explore the dynamics of the system by varying the control parameters, namely, the relative Rayleigh number (r) and the inclination angle of the cavity (β) together with the separation ratio (ψ) in the ranges of 1.0≤r≤2.0, 0°≤β≤90°, and −0.6≤ψ≤0. It is found that the inclination angle leads to a distinct trend for heat and mass transfer: the Nusselt number first decreases for small β, then gradually increases for moderate β, and finally decreases again for large β when r varies from 1.4 to 2.0. The optimal inclination angle lies in the range of 54°≤β∗≤64°, where the heat transport peaks. The Sherwood number initially decreases for small β, then increases with increasing β, and finally remains constant for large β. We present the bifurcation diagram of the solutions for different separation ratios, focusing on the distinct variation trends of the inclination angle. The corresponding heat- and mass-transfer properties of the flow on different branches of the bifurcation diagram are investigated. Furthermore, we explore the effect of the relative Rayleigh number, Prandtl number and Lewis number as well as the separation ratio on heat and mass transfer for various inclination angles, and obtain the Nusselt number as a function of the separation ratio and inclination angle.

Study on saline-alkali water distillation system by reflection enhanced solar heating

A saline-alkali water distillation system by reflection enhanced solar heating is proposed to treat the saline-alkali soil washing water. In this system, the heat concentration collector employs heat collecting plate to receive solar radiation energy, and converges to small-area steam generating tube through efficiently heat transfer. Without expensive optical tracking equipment, the system also employs an external reflector to reflect the solar radiation to the surface of the heat concentration collector. Thereby the energy flow density is further increased, and the useful energy and vaporization intensity is promoted. The latent heat of the steam is reused by heat recovery to enhance the energy utilization efficiency. The optimal inclination angles of reflector in different seasons and system performance were theoretically calculated. In the spring equinox, summer solstice, autumn equinox, and winter solstice, the optimal inclination angles of the reflector were 30°, 45°, 30°, and 15°, respectively. The freshwater production, useful energy, and heat recovery efficiency of the system were investigated by experiments. The daily freshwater production of the system was 17.04 kg, and the maximum production rate was 3.44 kg/h. The reflector increased the useful energy and freshwater production of the system by 33.68% and 35%, respectively. With heat recovery, the initial temperature of the saline-alkali water was increased to 53.8 °C and the freshwater production was increased by 13.16%.

Lightweight concrete with low-carbon artificial aggregates recycled from biomass ash and slurry waste

The development of artificial aggregates (AAs) significantly reduces carbon emissions of concrete production since the aggregates account for about 70% volume of all concrete ingredients. Therefore, a type of low-carbon AAs was prepared with full solid wastes of biomass ash (BA) and slurry waste (SW) through a pelletizing technique and carbonation curing methods. This study focused on evaluating the feasibility of AAs produced by the synergistic effect of BA and SW; identifying and optimizing the pelletization parameters through the response surface methodology (RSM) with experimental tests; analyzing the effects of blending amounts of BA on the properties of AAs; discussing the improvement of carbonation curing methods for AAs production; assessing the properties of the prepared lightweight concrete (LWC) with AAs. The results indicate the addition of 20 wt% BA lightened the bulk density of AAs by about 13% but weakened strength by nearly half due to its porous characteristics. The appropriate incorporation of 5 wt% BA could improve the individual pellet and cylinder compressive strength by about 2% and 16%, respectively. AAs cured in pressurized carbonation of 3 d and wet carbonation of 10 min demonstrated similar enhancement effects. Pressurized and wet carbonation curing showed respective superiorities in terms of improving effect and curing efficiency. The effects of inclination angle and moisture content on the average particle size are more significant than those of rotation speed, while rotational speed has a dominant effect on the bulk density. RSM simulations identified the optimal inclination angle, rotation speed, and moisture content as 45°, 38.5 r/min, and 37.5%, respectively. The LC40 high-strength LWC can be prepared by using full substitution pre-wetting AAs.

Investigating the effect of MXene/ethanol nanofluid in thermosyphon cooling of hybrid photovoltaic/thermal (PV/T) panels

Current research focuses on employing MXene/ethanol nanofluid (NF) as a working fluid in an array of two-phase closed thermosyphons (TPCT) for cooling the PV panel of hybrid solar photovoltaic/thermal (PV/T) system from the rear. Unique features such as high electrical conductivity, capacitive capacity, and hydrophilicity were the advantages of MXene nanoparticles. Moreover, comparisons between PV systems are provided in terms of performance and efficiency parameters. The results revealed that the optimum inclination angle for the panels was identified as 30°, and the optimum filling ratio was determined as 50 %. Applying NFs up to an optimal concentration of 1 % instead of the base fluid increased the temperature drop behind the panel, improved the panel output power, and enhanced overall efficiency. A temperature drop of 19.21 °C and an increase in electrical output of 1.62 W were observed behind the module at a 1 wt% MXene concentration. Therefore, the presented study discloses very high performance in PV/T systems.

Optimization of Parameters of Adaptive Spray System for Agricultural Sprayer

Introduction. When growing tall-growth crops (cereal crops in late the phases of development, corn, sunflower, etc.), there are used boom sprayers equipped with twin-fluid spray cones with fixed angles of inclination to the vertical of the spray cones. The working fluid is applied with such sprays are more intensively on the front side of the plant leaves while the intensity of covering the plants from the back side with the working fluid decreases. The development of the spray system will allow improving the quality of crop treatment with boom sprayers. Aim of the Study. The aim of the research is to determine experimentally the algorithm for changing the angles of inclination of a twin-fluid spray cone that provides the same intensity of applying working liquid to the leaves of high-growth plants. Materials and Methods. The research was carried out on a test bench by applying colored water to the front and rear sides of a tall-growth plant model moving at a specified speed. The experiment was carried out according to the method of optimal planning. The difference between the content of droplets on the front and rear sides of the tall-growth plant model was taken as an optimization parameter. Variable factors were the spray cone inclination angles and the operating speed of the sprayer. Results. The algorithm for changing the optimum values of the spray cone inclination angles depending on the sprayer speed was determined based on the equality of the first derivative of the optimization to zero parameter by the value of these angles. Discussion and Conclusion. According to the algorithm, when the sprayer operating speed increases from 1.2 to 3.2 m/s, the optimal angle of inclination to the front spray cone vertical changes linearly from 25 to 21 degrees, and the rear one ‒ from 46.7 to 57 degrees. This algorithm will allow justifying the technical specifications to develop a processor for automatic control of the spray cone inclination angles cones when the sprayer is operating.

Influence of load parameters during landslide slope reinforcement with soil nails based on self-drilling hollow steel bars on their bearing capacity and strength properties

Introduction. Soil nails are widely used to reinforce landslide slopes and ground-retaining structures in many countries, including Russia. The interaction of soil nails with the soil base is of high interest to both engineers and researchers. The method of increasing the stability of landslide slopes with soil nails has proved to be versatile and cost-effective. However, the process of designing soil nails is usually carried out using empirical and semi-empirical methods that may ignore a number of important factors.Aim. To determine the most optimal angle of soil nail inclination, as well as to analyze the characteristics of soil movement of a landslide slope along a potential sliding surface and their influence on the bearing capacity of the soil nail and its strength characteristics.Materials and methods. A review of scientific publications on the influence of load parameters during landslide slope reinforcement with soil nails based on self-drilling hollow steel bar on their bearing capacity and strength properties was carried out. The review sample included 11 publications most relevant to the topic under study. Calculations were carried out using the PLAXIS 2D software environment.Results. The conducted calculations and literature review allowed the optimal angle of soil nail inclination in the slope to be established, which corresponds to a value ranging from 0° to 5° to the horizon. The study also showed that the development of shear stresses along the soil nail in time exhibits a non-uniform nature. Therefore, the assumption of a constant value of shear stresses along the entire length of the nail or anchor root can lead to an overestimation of the soil bearing capacity.Conclusions. The obtained results have confirmed the relevance of further research into the influence of load parameters during the reinforcement of landslide slopes using soil nails.

Multivariate Evaluation of Photovoltaic Utilization Potential of Primary and Secondary School Buildings: A Case Study in Hainan Province, China

Modernization and industrialization have significantly increased energy consumption, causing environmental problems. Given that China is the largest energy user, the rise in building energy consumption necessitates clean energy alternatives. The purpose of this study is to summarize typical building models for primary and secondary schools in Hainan Province, and to use software to simulate and calculate the photovoltaic utilization potential of primary and secondary school buildings. In China, the government is usually the manager of primary and secondary schools, and due to their architectural characteristics, these buildings can be used to assess photovoltaic applications. The aim is to drive the application of photovoltaic systems in all types of buildings and promote urban energy reform. This study summarizes the types of primary and secondary school buildings in Hainan Province and analyzes them. It evaluates rooftop photovoltaic projects at the Second Middle School and the Siyuan School in Wanning City, Hainan Province, and uses PVsyst 7.2 software to assess the photovoltaic utilization potential. The results show that the optimal orientation in Hainan Province is south-facing, and the optimal inclination angle is 10° to 20°. The most favorable orientations of facade photovoltaic systems are 20° southeast or southwest. The longest dynamic investment payback period is approximately 15 years, and the environmental benefits are $0.012/kWh. The findings indicate significant potential for photovoltaic applications in primary and secondary school buildings. A combination of facade and rooftop photovoltaics can result in the zero-energy consumption of these buildings, reducing the pressure on urban power grids and achieving sustainable utilization.

The heat transfer and entropy generation of fin and inclined flat tube heat exchanger

The present work determines the appropriate inclination angles for each flat tube aspect ratio to increase the thermohydraulic performance without extending the heat exchange area. Furthermore, the amount of entropy generation was investigated to evaluate the exergy destruction for device configuration. A numerical simulation was performed with an inlet air velocity in a range from 3.5 to 5.0 m/s, flat tube aspect ratios (e) from 0.3 to 0.6, and tube inclination angles (β) from 10 to 50°. Analysis results indicated that the highest thermohydraulic performance of configuration e = 0.4 and e = 0.5 was obtained at β = 20°, and for configuration e = 0.3, it was obtained at β = 10−20°. The best thermohydraulic performance for configuration e = 0.6 was obtained at β = 20−30°. The thermohydraulic performance at optimal inclination angles extended from 1.011 to 1.069. The lowest entropy generation occurred at configurations with β = 50°. Increasing the aspect ratio and tube inclination angle increased the Colburn factor, increased the friction factor, and decreased entropy generation.

Study on silage mixing device of King Grass stalk particles based on DEM simulation and bench test

This study designed a silage mixing device for King Grass stalk particles and optimized the core component, the blender, based on the discrete element method (DEM). Through simulation tests, the effect of different blender forms, blade lengths and blade orientations on the Lacey mixing index (LMI) was studied, and the structural form of the blender was selected as the inclined blade-same-up impeller blender. Based on simulation tests, to verify the reliability of the simulation test and further determine the optimal blade inclination angle and mixing speed of the blender, a mixing experimental bench was built for bench tests. The LMI was compared between simulation and bench tests. At three speeds of 60, 80 and 100 r min- −1, the average relative errors are 2.3%, 2.1% and 1.5%, indicating that the simulation test can simulate actual tests well. The central composite design (CCD) was used to establish a binary quadratic regression model of the effects of blade inclination angle and mixing speed on LMI and mixing energy consumption. Using the NSGA-II algorithm, it was determined that the best inclination angle of the mixing blade is 42° and the best mixing speed is 78 r min−1.