Maximum Efficiency Increase Research Articles

Numerical investigation of the performance and flow field of an annular jet pump with throat aeration

The method of throat aeration was used to improve the performance of the annular jet pump (AJP). In order to study the influence of throat aeration on the performance and flow field of the AJP, the CFD method was used. The results show that at a low flow rate ratio ( q) the appropriate aeration rate can narrow or even eliminate the recirculation region. Meanwhile, the efficiency of AJP is improved at a medium-to-high q. Notably, the maximum increase in efficiency is 7.32% at q = 0.7 and the optimal aeration rate should be between 1% and 2%. Since the dynamic viscosity of air is much lower than water, a small amount of air attached to the wall can reduce friction loss. The air flows along the wall after the air aerated into the throat, reducing the shear stress between the high-speed jet and the wall. At a low q, most of the area in the throat is the high efficiency drag reduction region which the drag reduction rate exceeds 80%. Moreover, the high efficiency drag reduction region extends toward the diffuser when the q is high. In addition, throat aeration can optimize the pressure distribution near the wall and axis.

Performance investigation of a thermoelectric generator for vehicle exhaust recovery using graded pore density foam metal

Improving the efficiency of thermoelectric generators (TEGs) used to harness residual heat from automobile exhausts is crucial for their widespread adoption. To enhance fluid heat transfer, the Kelvin tetrahedron model is employed for metal foam, and a multiphysical field model of the thermoelectric generator based on metal foam is established. The effects of inserting metal foam with uniform and gradient pore densities into the heat exchanger on the performance of the TEG are investigated. Experimental verification is conducted by constructing a test bench with dimensions identical to those of the model The findings suggest that inserting foam metal significantly enhances the output performance of the TEG, resulting in increases in both output power and efficiency as pore density rises. At Ta = 573 K and ma = 30 g/s, the output power of the TEG with inserted 20 PPI foam metal is enhanced by 140.46 %, while the efficiency experiences a remarkable increase of 197.50 % compared to a smooth pipe. Compared to the performance metrics of uniform foam metal, the positive gradient foam metal exhibits a maximum power increase of 7.89 % and a maximum efficiency increase of 34.46 %, along with an average pressure drop reduction of 27.29 %.

A comprehensive review of the energy efficiency on nano coated fin and tube condenser

AbstractThe condenser is a piece of equipment used to effectively transfer heat from water to the environment. The fin and tube condenser is the most commonly used in commercial applications. The improved performance of heat transfer in the fin and tube condenser is a significant area of study all over the world because optimizing the efficiency of heat transfer in the condenser will contribute to enhancing the effectiveness of system performance. The vapor deposition, plasma spray, and thermal spray techniques are being used, and it is determined that a heat transfer enhancing coating improves condenser performance. This review discusses the nanomaterial coating over the fin and tube condenser in detail. The various nanomaterial coatings with various propositions and coating methods had been discussed with the evidence of previous researchers. At a 50‐degree inclination angle on the condensate plate, the condensate over the coating surface increases by more than 30%. The thermal properties of the working fluid are improved over the condenser, and the overall effectiveness of the condenser is increased by approximately 40% over the non‐coated condenser. A 1% volumetric concentration of Nanoparticles in the coated material achieves a maximum efficiency increase of 78.7%.

Conceptual design, energy, exergy, economic and water footprint analysis of CO2-ORC integrated dry gasification oxy-combustion power cycle

Among various techniques for CO2 capture and sequestration from coal-fired power plants, Dry Gasification Oxy-Combustion (DGOC) is a promising technology due to its efficiency, in-situ sulphur capture, and low water usage. In this work, a novel DGOC power cycle integrated with CO2-Organic Rankine Cycle (CO2-ORC) has been proposed for power generation and carbon capture. This study presents Energy, Exergy, Economic, and water footprint analysis of DGOC and its integration with CO2-ORC for different operating pressures and with different types of coal using Aspen Plus simulator. Steam cycle and CO2-ORC have been optimized for the process. Integration of CO2-ORC not only reduces the penalty for CO2 capture but also improves the efficiency by providing extra power output. Integration of CO2-ORC shows improvements in energy, exergy, and economics. Energy analysis shows a maximum increase in efficiency of 6.92% points by integrating CO2-ORC with DGOC for Bituminous coal and a maximum increase of about 6.7% points for high ash coal. The highest thermal energy efficiency of about 41.63% was noticed for Bituminous coal DGOC with CO2-ORC. Exergy analysis shows a positive impact of CO2-ORC integration for all operating pressures with a maximum increase of 5.74% points and 5.87% points for bituminous and high ash coals respectively. Economic analysis shows that combining CO2-ORC improves the specific capital cost of the cycle by 13.17% and 13.27% for the Bituminous and high ash coal cases respectively. Levelized cost of electricity (LCOE) analysis shows an improvement of 12.94% for Bituminous coal and 12.69% for high ash coal by the addition of ORC. The water usage for the plant is also reduced significantly with the addition of CO2-ORC.

Isomerization Directed Molecular Packing toward Suppressing Energy Loss in Nonfullerene Ternary Solar Cells

Organic semiconductors based upon conjugated frameworks are often isomeric and display distinct optoelectronic properties within minor structural variation. In this work, two isomeric nonfullerene acceptors (NFAs) ThMeCl-1 and ThMeCl-2, having the methyl and chlorine atoms attached on different positions of the electron-withdrawing end group, are synthesized and incorporated as the third component in ternary solar cells. Although these NFA isomers exhibit a similar bandgap, energy levels, and energy loss in their PM6 based binary devices, the efficiency enhancements in ternary devices differ significantly. Compared to ThMeCl-1, the incorporation of ThMeCl-2 in PM6:C5-16 solar cells enables less energy loss, leading to an extra 0.03 eV open-circuit voltage gain and a maximum efficiency increase from 17.8 to 18.9%. Grazing-incidence X-ray diffraction and molecular dynamics simulations reveal that this is attributed to the versatile intermolecular π–π stacking forms between ThMeCl-2 and the host NFA, which result in improved charge transport and suppressed recombination. This work provides a rational guidance for controlling the molecular packing in ternary systems to prepare high performance organic photovoltaics.

Structural optimization of multistage centrifugal pump via computational fluid dynamics and machine learning method

Abstract To implement energy savings in multistage centrifugal pumps, a return channel is utilized to replace the origin inter-stage flow channel structure, and then a single-objective optimization work containing high-precision numerical simulation, design variable dimensionality reduction, and machine learning is conducted to obtain the optimal geometric parameters. The variable dimensionality reduction process is based on the Spearman correlation analysis method. The influence of 15 design variables of the impeller and return channel is investigated, and seven of them with high-impact factors are selected as the final optimization variables. Thereafter, a genetic algorithm-backpropagation neural network (GA-BPNN) model is used to create a surrogate model with a high-fitting performance by employing a GA to optimize the initial thresholds and weights of a BPNN. Finally, a multi-island genetic algorithm (MIGA) is employed to maximize hydraulic efficiency under the nominal condition. The findings demonstrate that the optimized model’s efficiency is increased by 4.29% at 1.0Qd, and the deterioration of the pump performance under overload conditions is effectively eliminated (the maximum efficiency increase is 14.72% at 1.3Qd). Furthermore, the internal flow analysis indicates that the optimization scheme can improve the turbulence kinetic energy distribution and reduce unstable flow structures in the multistage centrifugal pump.

Multi-scale multi-physic coupled investigation on the matching and trade-off of conversion and storage of optical, thermal, electrical, and chemical energy in a hybrid system based on a novel full solar spectrum utilization strategy

In order to achieve a reasonable utilization of the full solar spectrum at low-cost, a photovoltaic/thermoelectric/electrolysis (PTE) hybrid system based on a novel full solar spectrum utilization strategy is proposed. The PTE mainly consist of a thermal collector with the spectrally selectively absorption fluid (water), a photovoltaic-thermoelectric (PV–TE) component and a water electrolysis component. Based the structure of the PTE, the full solar spectrum energy can be reasonably and efficiently allocated and utilized. For the complicated coupling physical process in PTE hybrid system, an integrated multi-scale multi-physic theoretical model is developed to optimize and investigate the PTE hybrid system. After the analyses on the multis-scale multi-physic effect of the air insulation layer between the thermal collector and the PV–TE component, it is found that removing air insulation layer leads to the less reflection loss and parasitic absorption, and more the maximum achievable photo current density and the internal heat source for TE component. Moreover, not only does the PV–TE component without the air insulation layer have higher efficiency (27.03%), but the concentration corresponding to the maximum efficiency increase to 31 from 3, which means more output power. By matching the structure and energy between components, the efficiency of the PTE hybrid system can be further improved, while the efficiency and energy storage of the PTE hybrid system can be adjusted according to the demand. Compared to single PV system, the efficiency of the PTE hybrid system has been increased by 15.38% at the concentration of 20, and this difference increases with the concentration. Moreover, the PTE hybrid system can simultaneously generate 200 W/m2 of hydrogen energy at the concentration of 20. In summary, the PTE hybrid system not only offers better performance (generation and storage), but also better integration, providing a guiding idea for the full solar spectrum utilization. Moreover, the multi-scale multi-physic coupled model also provides precise theoretical guidance for the optimization and design.

Investigating a new approach to enhance the discharge capacity of labyrinth weirs

AbstractClimate change has caused the inefficient operation of a significant number of old weirs to pass large discharges. Therefore, this study aims to increase the discharge capacity of the labyrinth weir. A new approach was proposed by modifying a labyrinth weir structure. The data was obtained from the quarter-round crest and different sidewall angles ranging from 8 to 35°. A conventional labyrinth weir was used for comparison. The results showed that the percentage of the notches area to sidewalls area of the weir (An/Aw) does not exceed 8%. Also, the percentage of the notches' length to total crest length (ΔL/Lc) does not exceed 32%. Also, the percentage of the notch depth to the sidewall depth (ΔP/P) does not exceed 30%. The other parameters are kept constant. These dimensionless terms provided a maximum compound coefficient of discharge of 0.74. Also, the compound discharge coefficient initially increased at low water head ratios and decreased at higher values of water head ratios. The regression empirical equations were generated. The maximum increase in efficiency was 10% for a sidewall angle of 6° when compared to conventional labyrinth weirs. The maximum improvement of the compound coefficient of discharge was 18.8% for a sidewall angle of 8°.

Influence of Bionic Waveform Leading Edge Blade on Drag Reduction Characteristics of Mixed Pump

Because the helical axial flow gas-liquid mixing pump has the great advantage of conveying gas-liquid two-phase mixed medium, it has become the main core equipment for deep-sea oil and natural gas exploitation. The gas phase aggregation and bubble movement trajectory in the impeller channel have been widely studied, but the increase of medium flow resistance caused by flow separation has not been deeply discussed. Combined with the Euler multiphase flow model and the SST k-ω turbulence model, the numerical calculation of the helical axial flow gas-liquid mixed pump is carried out. Under design flow conditions Q = 100 m3/h, head H = 30 m, speed n = 4500 r/min, specific speed ns =213.6 r/min, and under different inlet gas content conditions, the influence of the bionic waveform leading edge blade on drag reduction characteristics of the helical axial flow gas-liquid mixed pump was investigated. By designing the blade with a leading-edge structure with different heights and pitches, the separation of the mixed medium and the suction surface is effectively suppressed, and the flow resistance of the medium in the 1/10 area of the inlet end of the blade is reduced. The results show that when the height A is 0.25%L and the pitch λ is 12.5%h, the maximum drag reduction rate in this region is 52.6%, the maximum increase in efficiency of the mixed pump is 2.2%, and the maximum increase in head is 4.8%. This study can provide technical support for flow drag reduction in gas-liquid mixed pump.

Magnetophoretically enhanced separation of particles in engine oil filters

This study conceptualizes the use of magnetic fields to improve the performance of engine oil filters for the first time. Experimental analysis of the particles extracted from multiple engine oil filters indicates the sensitivity of a large portion of them to external magnetic fields indicating the capability of the magnetophoresis to separate particles. The effect of several parameters, including flow velocity, particle size, oil viscosity, magnetic field intensity, and dipole arrangement on the capture efficiency of the magnetic field is numerically investigated. The capture efficiency of the magnetic field substantially increases with increasing its intensity. Increasing the particle diameter at a fixed particle density or increasing the particle density at a fixed diameter increases the capture efficiency. Also, increasing the oil viscosity generally decreases the magnetic field capture efficiency. Using more dipole moments, up to an optimum number, and placing them equidistantly around the filter raises the capture efficiency significantly. The efficiency rise is higher at lower magnetic dipole moments. The maximum efficiency increase obtained by increasing the dipole number is 20%. When the overall dipole moment is fixed, a similar trend is observed for the capture efficiency, although with a different optimum dipole number. Finally, employing a compound magnetic field generated by means of a magnetic belt to assist particle separation in oil filters is proven to be a promising idea.

Deep-Learning Algorithmic-Based Improved Maximum Power Point-Tracking Algorithms Using Irradiance Forecast

Renewable energy is a key technology for achieving carbon-free energy transitions, and solar power systems are one of the most reliable resources for achieving this. Solar power systems have a simple structure and are inexpensive. However, depending on the input irradiance, the existing maximum output control algorithm (P&O) has disadvantages due to its slow transient response and steady-state vibration. Therefore, in this paper, we propose a maximum output control algorithm based on a deep learning algorithm that can predict the input irradiance. This can achieve a quick transient response and steady-state stability. The proposed method predicts the irradiance based on the output voltage/current and power of the photovoltaic (PV) system and calculates the duty ratio that can accurately follow the maximum output point according to the irradiance. The deep learning model applied in this study was trained based on the experimental results using a 100 W PV panel, and the performance of the proposed algorithm was verified by comparing its performance with that of the conventional algorithm under various input irradiance conditions. The proposed algorithm exhibits a maximum efficiency increase of 11.24% under the same input conditions as those of the existing algorithms.

Experimental analysis on CPA-free thin-disk multipass amplifiers operated in a helium-rich atmosphere

We present an experimental investigation on the benefits of helium as an atmospheric gas in CPA-free thin-disk multipass amplifiers (TDMPAs) for the amplification to average powers exceeding 1 kW and pulse peak powers reaching 5 GW. Both the performance of the amplifier and the properties of the amplified sub-400 fs laser pulses centred at a wavelength of 1030 nm are compared for different helium concentrations in air, outlining and quantifying the benefits of a helium-rich atmosphere. The amplification of 100 µJ pulses in an atmosphere with 60% helium instead of air led to a maximum increase in efficiency from 24% to 29%. This translated into an increase of average output power and pulse energy of 34 W (i.e +19%) and 0.34 mJ (i.e. +19%) respectively. At the same time an improvement of the beam quality from M2 = 1.18 to M2 = 1.14 was achieved. For the amplification of 10 µJ pulses to over 1 kW of average power an atmosphere with 33% helium led to an improved beam pointing stability by a factor of 2. Moreover, the beam propagation factor M2 improved by 0.1, and the power stability improved by approximately 10%.

Flow Characteristics and Optimization Design of the Stator–Rotor Cavity of the Full Tubular Pump

The full tubular pump device is taken as the research object in this article. This research method adopts the numerical simulation technology based on the SST (Shear-Stress-Transport) k-ω turbulence model to explore the internal flow characteristics of the stator–rotor cavity of the full tubular pump and optimize the stator–rotor clearance structure. The research shows that under the design conditions, compared with the axial flow pump, the torque increases by 47.91 N·m at the stator–rotor cavity structure and the efficiency decreases by about 20%. The torque at the rotor clearance of the full tubular pump accounts for about 50% of the torque at the rotor. Since there is a large area of backflow on both sides of the cavity, and there is a vortex structure on the inlet side of the cavity, it shows that the rotor structure and its area greatly affect the operating efficiency of the pump device. With the reduction in the rotor force area, the clearance length, and the outer diameter of the disc, the operating efficiency of the pump device gradually increases. Under the design conditions, the optimized model has a maximum efficiency increase of 14.04% and the torque at the cavity rotor is reduced by 39.25 N·m. The results show that the operating efficiency of the full tubular pump is closely related to its rotor structure area, and the force area of the rotor structure needs to be controlled in the actual design process.

A global thermal node model for no-load indirect solar dryer

ABSTRACT This paper presents a global thermal node model for predicting heat transfer in no-load indirect solar dryer. The overall influence of the interaction of the indirect solar dryer with the uppermost soil layer is considered. The mathematical model describing the solar drying system with a double-pass air-circulation collector is derived. Based on the Moore and Fisch approach, the soil surface fluxes are calculated using the surface layer similarity theory. The drying air temperature distribution based on dynamic descriptions of the drying environment is studied. The unsteady convection heat transfer results low thermal efficiency of the dryer at low air speed. The linear increase of the inner air speed from to makes the maximum efficiency increases of . When the offsetting air speed undergoes a convex quadratic increase, the average value of the energy efficiency in this case increases of compared to the scenario of constant air speed.

Enhancement of distillate output of solar still by cooling glass cover

The difference in temperature between the temperature of the basin water and the temperature of the glass cover is the most important regulating factor for getting yield from a solar still. The higher the temperature differential, the more distillate the solar still produces. This temperature difference can be enhanced either by increasing the temperature of basin water by decreasing glass cover temperature or combining both strategies together. A strategy for lowering the temperature of a glass cover is to cool it with air or flowing water. Cooling the glass cover by water not only boosts the production of the still but also cleans it. The presence of dust particles on the glass cover reduces the amount of solar energy impacting on water in basin, which is continuously cleaned by water flowing over it. In present work a detailed review on the various methods used to cool glass cover have been discussed. The decrease in temperature of cover is up to 20oC by cover cooling and the maximum increase in efficiency of solar still by cover cooling is about 20%.

Hydrodynamic Performances of Aeronautical Propeller for Drones

Currently, several countries already invest on the application of drones for different scopes. These purposes are mainly civilian and military and some of these include the presence of water as search and rescue, inspection of pipelines, getting a bird’s eyes view over oil spills or structural integrity monitoring of bridges. For this reason, an interesting feature for drones is their ability to maneuver in fluids with different density as air and water. This research topic, shows strong scientific potentiality but it also represents a great challenge from scientific and technical view point: i) aeronautical propeller for drones in water must generate reverse thrust or braking force through an off-design rotation in off-design condition (different fluid’s density); ii) the propeller rotational velocity in water is generally one order of magnitude lower than the one for air application requiring the motors to be properly desing to meet such a wide operational range. In this paper, an experimental campaign aimed at the performance quantification of a three-bladed propeller for drone propulsion in water has been carried out in a towing tank. In particular, the generated forces are acquired through a load cell for different advance ratios J provided by varying both rotational regime and free stream velocity. The results show expected losses in the performance for the off-design rotation in terms of both thrust and efficiency. At low rotational speeds, higher values of efficiency are presented for small advance ratio. The maximum efficiency increase for higher RPS and it’s slightly influenced by small variation of propeller disk angle.

Performance of Magneto Hydro Dynamic (MHD) as a Power Generation Support Tool

<p>Magnetohydrodynamics is a method for generating electricity by utilizing the interaction between a magnetic field and an electrolyte fluid. MHD components: salt water electrolyte, Neodymium N52 magnet, and Cu-Zn electrode. The MHD used is a coarse salt water electrolyte. The purpose of the MHD model is as an innovative technological breakthrough that is used to support increasing the efficiency of the power generation system. The lowest efficiency is shown in the second data with variations in salt content of the 5 grams/liter experiment without MHD support, which is 0.08%. The highest efficiency is shown in the twentieth data with variations in salt content of the 95 gram/liter experiment supported by MHD, which is 0.59%. The maximum efficiency increase that can be achieved is 0.37% with variations in salt content of 60 grams/liter.</p>

Aerodynamic Efficiency Improvement on a NACA-8412 Airfoil via Active Flow Control Implementation

The present paper introduces a parametric optimization of several Active Flow Control (AFC) parameters applied to a NACA-8412 airfoil at a single post-stall Angle of Attack (AoA) of 15∘ and Reynolds number Re = 68.5×103. The aim is to enhance the airfoil efficiency and to maximize its lift. The boundary layer separation point was modified using Synthetic Jet Actuators (SJA), and the airfoil optimization was carried on by systematically changing the pulsating frequency, momentum coefficient and jet inclination angle. Each case has been evaluated using Computational Fluid Dynamic (CFD) simulations, being the Reynolds Averaged Navier–Stokes equations (RANS) turbulence model employed the Spalart Allmaras (SA) one. The results clarify which are the optimum AFC parameters to maximize the airfoil efficiency. It also clarifies which improvement in efficiency is to be expected under the operating working conditions. An energy balance is presented at the end of the paper, showing that for the optimum conditions studied the energy saved is higher than the one needed for the actuation. The paper clarifies how a parametric analysis has to be performed and which AFC parameters can be initially set as constant providing sufficient previous knowledge of the flow field is already known. A maximum efficiency increase versus the baseline case of around 275% is obtained from the present simulations.

Multi-Objective Optimization for the Radial Bending and Twisting Law of Axial Fan Blades

The performance of low-pressure axial flow fans is directly affected by the three-dimensional bending and twisting of the blades. A new blade design method is adopted in this work, where the radial distribution of blade angle and blade bending angle is composed of standard-form rational quadratic Bézier curves. Dendrite Net is then trained to predict the pneumatic performance of the fan. A non dominated sorting genetic algorithm is employed to solve the global optimization problem of the total pressure coefficient and efficiency. The simulation results show that the optimal blade load distribution along the radial direction becomes uniform, and the suction surface separation vortex and passage vortex are restrained. On the other hand, the tip leakage vortex is enhanced and moves toward the blade leading edge. According to the experimental results, the maximum efficiency increases by 5.44%, and the maximum total pressure coefficient increases by 2.47% after optimization.

Thermal efficiency of a ferrofluid-based flat-plate solar collector under the effect of non-uniform magnetic field

• A flat-plate solar collector with ferrofluid under magnetic field is studied. • Without magnetic field, the collector's efficiency increased with flow rate increase. • Without field, the maximum efficiency increase is 39.9% for 0.8 vol% and 0.05 kg/s. • The field effect on the efficiency enhancement increased with decreasing flow rate. • The maximum efficiency enhancement of is 52.15% for 0.8 vol%, 0.0083 kg/s, 1.0 T. Mn–Zn Fe 2 O 4 magnetic nanoparticles have high magnetization capability. They can be stimulated well with an external magnetic field for producing a high magnetic body force, which is added to the momentum equation. Applying an Mn–Zn Fe 2 O 4 ferrofluid in a flat-plate solar collector influenced by a strong magnetic field can be a compelling method in improving the thermal efficiency of the collector compared with other nanofluid-based ones. This experimental investigation, for the first time, presents an Mn–Zn Fe 2 O 4 /water ferrofluid-based flat-plate solar collector, equipped with a set of permanent magnets, to study the impact of the non-uniform magnetic field on the collector efficiency based on ASHRAE Standard. Simultaneous effect of the various parameters like the nanoparticles volume fraction ( φ = 0, 0.2, 0.4, and 0.8%), the fluid flow rate ( m ̇ = 0.0083–0.05 kg/s), and the remanent magnetization of the magnets ( B r = 0.0–1.0 T) on the collector efficiency have been taken into the consideration. According to the results, using the ferrofluid-based collector has a relatively significant impact on the collector efficiency than other nanofluid-based collectors. For the ferrofluid case studies without a magnetic field, the maximum enhancement in the collector efficiency compared to water is 39.9% for the case with φ = 0.8% and m ̇ = 0.05 kg/s. Also, when the magnets are used, the collector efficiency is improved with volume fraction augmentation and decreasing the fluid flow rate. Finally, with applying the magnetic field, the maximum enhancement in the efficiency has been 52.15% obtained for φ = 0.8%, m ̇ = 0.0083 kg/s, and B r = 1.0 T.