Increase In Average Efficiency Research Articles

Assessment of a NaOH-based alkaline electrolyser’s performance: System modelling and operating parameters optimisation

Most of the scientific research is focused on KOH-based alkaline electrolysers, while NaOH-based ones are unexplored although they present interesting features. This paper presents a semi-empirical model developed in the Python environment to predict a NaOH-based alkaline electrolyser’s performance to cover such a research gap and perform an optimisation procedure of electrochemical parameters. A sensitivity analysis has been carried out to study how its performance changes while varying the: i) NaOH content, ii) pressure, and iii) both. Separately, the best result has been obtained with a NaOH content and an operating pressure of 8% and 6.5 bar, respectively. Furthermore, the same values have been recorded even by varying both the NaOH content and the operating pressure. Specifically, a maximum average efficiency increase of 3.57% at 35°C, 0.17% at 40 °C, and 3.74% at 35°C in the case of NaOH content, pressure, and both, respectively.

Maximizing oscillating water column efficiency: The impact of vertical plate and guide vane

This study is centered on improving the hydrodynamic efficiency of a conventional Oscillating Water Column (OWC) that has a rectangular cross-section. The OWC chamber is modified by introducing a centrally installed vertical plate, dividing it into two sub-chambers, and further incorporating a quarter-circle guide vane beneath the vertical plate. Physical experiments are conducted under three scenarios: the conventional single-chamber OWC, the OWC with double sub-chambers separated by a vertical plate, and the OWC with both a vertical plate and a guide vane. Hydrodynamic efficiency is examined across varying Power Take-Off (PTO) dampings, incident wave frequencies, and wave heights. Results demonstrate substantial efficiency improvements with the vertical plate, particularly at lower dimensionless wave frequencies. The guide vane also boosts these benefits by preventing vortex formation due to flow separation, resulting in a total average efficiency increase of 42 %. Visual observations highlight the transition from sloshing to piston-like motion induced by the vertical plate, contributing to increased kinetic energy and improved efficiency. The study highlights that basic but effective modifications can substantially enhance OWC efficiency, suggesting promising directions for the development of wave energy conversion technology.

The Evaluation of WaveSAX Power Generation to Support Port Energy Self-Sufficiency

Remarkable advancements have been made in wave energy converters, notably the innovative WaveSAX technology—an oscillating water column system conceptually designed for coastal structures. Proven effective in existing installations, particularly at Civitavecchia Port, Italy, where the WaveSAX-1 prototype was tested in 2018 and the WaveSAX-2 was updated in 2021. The device’s power generation capacity was evaluated using a Simulating WAves Nearshore (SWAN) model that simulated 30 years of wave conditions. Validation with radar and Acoustic Doppler Profiler instruments showed excellent performance in wave height simulation. Results revealed higher wave power generation near the harbor breakwater, surpassing offshore levels, especially in central and northern sections. WaveSAX-2, featuring an improved Wells turbine, demonstrated a remarkable 37% increase in average efficiency compared to WaveSAX-1. If a linear WaveSAX array were installed, it could produce 4 GWh annually, satisfying 20% of the port’s energy needs and reducing around 2800 tCO2e/year. Doubling arrays and incorporating triangular modules could significantly enhance sustainability for port operations, offering a promising path toward self-sufficiency and environmental responsibility.

High-Efficiency Inertial Separation of Microparticles Using Elevated Columned Reservoirs and Vortex Technique for Lab-on-a-Chip Applications.

The discovery of circulating tumor cells (CTCs) has envisioned an excellent outlook for cancer diagnosis and prognosis. Among numerous efforts proposed for CTCs isolation, vortex separation is a well-known method for capturing CTCs from blood due to its applicability, low sample volume requirement, and ability to retain cell viability. It is a label-free, passive, low-cost, and automated method, making it an ideal solution for lab-on-a-chip applications. The previous designs that employed vortex technology have shown reaching high throughput and 70% separation efficiency although it was after three processing cycles which are not desired. Inspired by our earlier design, in this work, we redesigned the chip geometry by elevating the columned reservoir height to capture more particles and consequently reduce particle-particle collision, eventually improving efficiency. So, a height-variable chip with fewer elevated columned reservoirs (ECRs) was employed to isolate 20 μm microparticles representing CTCs from 8 μm microparticles. Also, numerical simulations were conducted to investigate the third axis contribution to the separation mechanism. The new design with ECRs resulted in a 14% increase in average efficiency, reaching ∼80% ± 8.3% in microparticle separation and 61% purity. Moreover, the proposed chip geometry demonstrated more than three times higher capacity in retaining orbiting particles up to 1300 in peak performance without sacrificing efficiency compared to earlier single-layer designs. We came up with an upgraded injection system to facilitate this chip characterization. We also presented an effortless and straightforward approach for purging air bubbles trapped inside the reservoirs to preserve regular chip operation, especially where there is a mismatch between channel and reservoir heights.

Efficiency and productivity analysis of innovation, human capital, environmental, and economic sustainability nexus: case of MENA countries.

Innovation, human capital, economic, and environmental nexus is essential in sustainable development. The Middle East and North Africa (MENA) is an emerging market with the potential to transcend the dilemma of attaining economic and environmental sustainability. Data envelopment analysis through the Malmquist-Luenberger productivity index is utilized to estimate MENA country's innovation, human capital, economic, and economic sustainability efficiency and productivity. Results indicate an upward trend in efficiency, with a 26% increase in average efficiency between 2017 and 2019 compared to 2011 and 2016. However, there is variation in efficiency between countries. The decomposition of the productivity index into technical change and technological change indicates that the efficiency growth in 2017-2019 could be attributed to technical improvement than technological increase. However, there is a shift to more technological progress than technical increase. Study shows that developing human capital and capacity is as integral to sustainable development as innovation advancement. Strategies to simultaneously augment human capital and innovation towards sustainable development are presented.

Precisely nanostructured HfO2 rear passivation layers for ultra‐thin Cu(In,Ga)Se2

AbstractThe quest for material‐efficient Cu(In,Ga)Se2 (CIGS) solar cells encourages the development of ultra‐thin absorbers. Their use reduces material consumption and energy usage during production by increasing the throughput. Thereby, both the bill of materials as well as the energy and capital costs are reduced. However, because thin absorbers are prone to increase back contact recombination, back surface passivation schemes are necessary to reach a similar or higher conversion efficiency than for absorbers with conventional thickness. Here, we investigate nanostructured hafnium oxide (HfO2) rear passivation layers for ultra‐thin CIGS solar cells. We fabricate regular arrays of point contacts with 200 nm diameter through HfO2 layers with thicknesses between 7 and 40 nm using electron beam lithography and reactive ion etching. The current–voltage curves of solar cells with a 500 nm thick CIGS absorber layer and the nanostructured passivation layer show improved performance concerning Voc and Jsc compared to non‐passivated reference devices. Furthermore, external quantum efficiency and optical reflection confirm an effective passivation behavior, with an average efficiency increase of up to 1.2% for the cells with the 40 nm thick HfO2 layer. In addition, simulation work shows that even 40 nm thick HfO2 passivation layers have only a minimal effect on the optical properties of ultra‐thin CIGS solar cells, and hence, the photocurrent increase verified experimentally stems from electrical improvements caused by the HfO2 layer passivation effect. We also investigate the impact of ultra‐thin (0.3, 0.6, 1.3, and 2.5 nm) non‐patterned HfO2 passivation layers on the same type of solar cells. However, these results showed no improvement in solar cell performance, despite an increase in the current density with layer thickness.

Design and Implementation of Automatic Water Spraying System for Solar Photovoltaic Module

Photovoltaic (PV) cell has a characteristic of decrease in power beyond a certain temperature. This decrease in power is due to a drop in the open circuit cell voltage. This decreases the efficiency of the PV cell. The objective of this research is to increase the efficiency of PV cells by reducing the PV cell temperature and reflection loss. The cell temperature and reflection loss can be reduced by spraying water over the PV cells. On spraying water over the USP36, 24V PV module, the power is found to be increased. The test result shows a 1V to 2V increase in voltage, with an efficiency increment of 1% to 1.27%. The test results of USP37 show the voltage increase of 1.2 V to 2.1 V in the PV module voltage. Due to the increase in voltage, efficiency increment of 1.29% is observed. The efficiency of USP36 with water spraying is more than the efficiency of USP37 without water spraying. In the PV power systems, an average increase in efficiency of 0.5% is observed.

Comparative Study of Conventional and Water Circulating-Heat Sink Cooling Base Thermoelectric Generator System for Optimum Solar Thermal Waste Heat Recovery

A novel technique for waste heat recovery in solar thermal power generation is investigated through experimentation and systematically presented. Power generation using Thermoelectric Generator (TEG) is a promising technique in waste heat recovery application. In this topology, TEG array is directly attached to the back of the solar Photovoltaic panel (model AP-AM15) to receive the transmitted heat at the back of the PV panel as waste heat. More so, a circulating water-heat sink is attached to the TEG cold side to improve the temperature gradient. Base on Seebeck effect, the TEG directly converts the temperature difference into electricity. The experimental result shows that efficiency between the range of 2.1% and 4.7% for the conventional cooling system while the output power approximately ranges between 0.05W and 0.47W, the circulating water-heat sink technique has efficiency ranging between 2.9% and 10.3% with output power between the range of 0.10W and 2.2W. The daily average increase in efficiency was found to be 263.76%. This shows that the daily average power is improved by a factor of 2.6376 with the water circulating water-heat sink technique. This is an indication of waste heat recovery from the solar thermal power generation.

Analisis Pengaruh Nilai Beban Unit Terhadap Efisiensi dan Heat Rate Turbin Pada Pltu Moramo

Moramo steam power plant is one of steam power plant in Indonesia that using coal as it fuels with capacity of 2x50 MW. Power produced by Moramo steam power plant is not always in constant condition because of fluctuation power in distribution grid with corresponding of power demand. One of the main indicators of steam turbine performance is the efficiency of steam turbine cycle and turbine heat rate. This research conducted to analyzes the effect of changes in power produced by Moramo steam power plant on the efficiency and turbine heat rate using a thermodynamic analysis approach and energy input-output methods. Analyzed data in this research is actual data during normal operation that taken from Distributed Control System (DCS). Results of this research indicated that the more the power produced by Moramo steam power plant the better of performance of its steam turbine. It is showed by the increase of average efficiency from 39.138% on 30 MW Net load to 39.369 % on 40 MW Net load, and increase to 39.976 % on 50 MW Net load. Furthermore, the increase of performance also showed by the decrease of its average turbine heat rate from 10137.79 kJ/kWh on 30 MW Net load to 9633.95 kJ/kWh on 40 MW Net load, and decrease to 9333.77 kJ/kWh on 50 MW Net load.Keywords: Load, efficiency, heat rate, steam power plant, steam turbine

Heat transfer performance of wet porous solar collectors under periodic conditions

AbstractFourier's law was often used to study the heat transfer of collector plates. However, some scholars have found that under time‐varying periodic boundary conditions, using Fourier's law for research will produce certain deviations. In the current work, periodic boundary conditions are used, so the effect of non‐Fourier efficiency on the heat transfer of the collector plate needs to be considered. Based on the Cattaneo–Vernotte equation, a heat transfer model of the solar collector plate with a limited heat transfer rate is constructed, and the problem is solved by the lattice Boltzmann method. On this basis, the influence of radiation, porous media, humidity, and relaxation time on solar collectors is considered. And the average efficiency, tip temperature, and exergy loss of the collectors are quantitatively analyzed. The results show that when the non‐Fourier effect is considered, the tip temperature of the collector plate decreases, the average efficiency and the exergy loss increase. Moreover, with the increase of relaxation time, the tip temperature is lower, the efficiency and the exergy loss are greater. As the humidity and radiation increase, the tip temperature decreases, and the exergy loss and average efficiency increase. When other factors remain unchanged, the average efficiency, tip temperature, and exergy loss increased with an increase in porosity.

Dual Efficiency and Productivity Analysis of Renewable Energy Alternatives of OECD Countries

This paper examines the dual efficiency of bioenergy, renewable hydro energy, solar energy, wind energy, and geothermal energy for selected OECD countries through an integrated model with energy, economic, environmental, and social dimensions. Two questions are explored: Which renewable energy alternative is more dual efficient and productive? Which renewable energy alternative is best for a particular country? Data envelopment analysis (DEA) is used for the efficiency evaluation, and the global Malmquist productivity index is applied for productivity analysis. Results indicate bioenergy as the most efficient renewable energy alternative with a 20% increase in average efficiency in 2016 compared to 2012. Renewable hydro energy, wind energy, and solar energy show a 17.5%, 16%, and 11% increase, respectively. The average efficiency growth across all renewable energy alternatives signifies major advancement. Country performance in renewable energy is non-monolithic; therefore, they should customize their renewable energy portfolio accordingly to their strengths to enhance renewable energy efficiency. Renewable hydro appears to have the most positive productivity change in 2016 compared to 2012, while solar energy regressed in productivity due to its scale inefficiency. All renewable energy alternatives have relatively equal average pure efficiency change. The positive trend in efficiency and productivity provides an incentive for policy makers to pursue further development of renewable energy technologies with a focus on improving scale efficiency.

Experimental study of a hemispherical three-dimensional solar collector operating with silver-water nanofluid

In this experimental study, a fixed three-dimensional solar collector with a hemispherical geometry has been evaluated in accordance with ASHRAE standards. The collector features spiral tubes that transport fluid from the inlet to the outlet with no riser. Pure water and Ag-water nanofluid at different nanoparticle concentrations (0.1, 0.2 and 0.3%) and different flow rates (0.1–0.6 GPM) were tested under different environmental conditions (temperature and radiation). The results show that this hemispherical solar collector, owing to its geometry and the specific arrangement of its pipes in relation to the overall surface area, exhibits promising thermal performance, making it a viable candidate for both domestic and industrial deployment. The average increase in efficiency when switching from water to Ag-water nanofluid was found to be around 11%, with the maximum efficiency (61.1%) occurring at a nanoparticle concentration of 0.3% and a flow rate of 0.6 GPM.

Study on the fuel economy of fuel cell electric vehicle based on rule-based energy management strategies

This paper designed a fuel cell power system statically to meet the dynamic requirement, with the fuel cell's model and the vehicle model built by GT-Suite. The influence mechanism of different rule-based energy management strategies on the fuel economy was studied. The results revealed that fuel cell worked more efficiently with fuzzy logic control strategy than with power-follower strategy, given an average efficiency increase of 13.27%. Compared with the on/off control strategy, the heat dissipation was reduced by 79.67% with the fuzzy control strategy. Considering the feasibility of real-time implementation, robustness, and low computational burden, the on/off control strategy was optimised by a non-dominated sorting genetic algorithm (NSGA-II), based on ModeFRONTIER (MF). Compared with the original strategy, the fuel consumption was reduced by 17.9%.

Efficiency Comparison and Efficiency Development of the Metallurgical Industry in the EU: Parametric and Non-parametric Approaches

This article deals with the development of technical (production) efficiency in the metallurgical industry in EU countries with an emphasis on the situation in the Czech Republic. The efficiency of individual countries was estimated for the period from 1995 to 2015. The parametric stochastic frontier analysis method with different settings was chosen to estimate efficiency and the results were verified using a competitive non-parametric data envelopment analysis method. It was found that during the period under review, there was an average increase in efficiency in the metallurgical industry. The largest increase in efficiency (confirmed by all types of models) was observed in the Czech Republic. A visible positive efficiency shift was also recorded in Spain and Greece. Surprisingly, there has been a decline in efficiency in Sweden and Italy.

The effect of guide vane type on performance of multistage energy recovery hydraulic turbine (MERHT)

AbstractIn this work, we theoretically analyzed the main factors affecting performance of multistage energy recovery hydraulic turbine (MERHT), and found that the arc radius (r) of the edge at the outlet section of the runner guide vane is the determining factor of the hydraulic efficiency of hydraulic turbines. To further improve the performance of the MERHT, a numerical model is then proposed to optimize the arc radius. The MERHT-type DCSGT250-175 × 9 was taken in the simulation. The hydraulic efficiency ηh and the corresponding distributions of pressure and velocity were numerically studied with four different values of r ranging from 133.5 to 138 mm. It is found that the flow state and the flow field distribution were the best when r equals to 134 mm. With the optimum r, the external diameter of the runner guide vane (D) was further adjusted, which can lead to 3.9% increase of average efficiency according to the simulation results.

ASSESSMENT OF GOLD AND/OR CRUDE OIL AS INVESTMENTS FOR PORTFOLIO DIVERSIFICATION. A WARSAW STOCK EXCHANGE CASE STUDY

The purpose of the study is to assess whether the inclusion of investments in gold and/or crude oil improves an investment portfolio consisting of shares of enterprises included in the WIG20 index (traditional investments). All possible combinations of investment portfolios with minimal risk and maximum efficiency were tested. The portfolios were determined based on Markowitz’s portfolio theory. All results were compared with a naive strategy. In total, nearly 55,000 investment portfolios consisting of three, four or five investments were constructed. The study showed that the application of portfolio theory contributes to obtaining better results than a naive strategy. The minimum risk portfolios that included gold and crude oil showed a risk reduction of 0.39 p.p. on average and a maximum cumulative loss of 7.85 p.p. on average. Portfolios with maximum efficiency achieved an average increase in the rate of return of the investment portfolio of 0.024 p.p. and an average increase in efficiency of 0.0256.

Conjugated ionic (co)polythiophene-based cathode interlayers for bulk heterojunction organic solar cells

The incorporation of conjugated polyelectrolytes as cathode interlayers in organic photovoltaics has been proven to be an effective way to boost the device efficiency. Nevertheless, more detailed investigations of the structure–property relationships of these interlayer materials, in particular related to the film deposition behavior, can provide further insights into their mode of action. With this aim, a series of ionic (co)polythiophenes is successfully synthesized via Kumada catalyst-transfer condensation polymerization and subsequent introduction of ionic moieties on the polymer side chains. Both the topology (i.e. homopolymers, random and block copolymers) and the amount of ionic groups are systematically varied. The polymers are fully characterized and then applied as cathode interlayers in polymer solar cells based on PCDTBT:PC71BM, affording an average efficiency increase of ∼15%. The structural screening on one hand indicates that the efficiency gain is a rather general phenomenon for this material class. On the other hand, the best photovoltaic responses are observed for the conjugated polyelectrolytes with a higher triethylene glycol side chain ratio and the block copolymer structure performs slightly better as compared to the random copolymer with the same (50/50) monomer ratio. Based on these findings, the field can move on to a more rational development of novel interfacial materials and thereby push the device efficiency even further.

CFD simulations to optimize the blade design of water wheels

Abstract. At low head sites and at low discharges, water wheels can be considered among the most convenient hydropower converters to install. The aim of this work is to improve the performance of an existing breastshot water wheel by changing the blade shape using computational fluid dynamic (CFD) simulations. Three optimal profiles are investigated: the profile of the existing blades, a circular profile and an elliptical profile. The results are validated by performing experimental tests on the wheel with the existing profile. The numerical results show that the efficiency of breastshot wheels is affected by the blade profile. The average increase in efficiency using the new circular profile is about 4 % with respect to the profile of the existing blades.

Ultrahigh Efficiency HCPV Modules and Systems

Semprius manufactures high-concentration photovoltaic (HCPV) modules and systems. Module characterization and quality control methods are described in this paper. Module efficiency distribution for thousands of modules is presented, currently showing an increase in average efficiency from 33% in 2013 to 35%. Data from modules and systems in the field are presented showing consistent performance over all seasons and no apparent degradation after 3 years. Finally, the effect of ambient temperature and wind speed on performance was studied.

Influence of Soft Magnetic Material in a Permanent Magnet Synchronous Machine With a Commercial Induction Machine Stator

This paper presents the efficiency study of a 6-pole and 2-pole induction motor (IM), converted into a 6-pole and 2-pole permanent magnet synchronous machine (PMSM). Firstly, the stator of the IM was kept unchanged and the rotor was converted into a permanent magnet (NdFeB magnets) rotor, resulting in higher average efficiency. Secondly, we investigated how much the efficiency can be increased by replacing the electrical steel in the stator by another material grade. The numerical approach is based on the finite element method (FEM), taking into account the rotor movement. Iron losses are computed according to the loss separation theory. From measurements and simulations, it is observed that the efficiency increases significantly compared to the original IM. The average efficiency of the orig inal 1.5 kW IM converted into the 1.5 kW PMSM led to a 14% higher efficiency in a speed range 0.5Ωnom - Ωnom and torque range 0.5Tnom - Tnom. When the stator iron is replaced by M235-35A laminations with the same geometry, the average efficiency increases by an additional 2% for the 1.5 kW PMSM with modified stator.