Electric Power Efficiency Research Articles

Performance analysis of a bio-diesel fired engine bottoming with micro-ORC

The purpose of this work is to investigate the performance in terms of electric power and electric efficiency of a 11kW bio-diesel internal combustion engine (ICE) coupled with a micro Organic Rankine Cycle (ORC) both in design and off-design conditions. A zero dimensional (0D) thermodynamical engine model has been developed to predict the electric and thermal power with 100% biodiesel fuel (B100). B100 has been selected for the performance analysis of the integrated system due its lower environmental impact. For the ORC system, a subcritical thermodynamic model has been used with various working fluid (R245fa, R1233zd(E), R134a, R1234ze(E) and R1234ze(Z)). A plate heat exchanger (PHEX) has been adopted as evaporator of the organic cycle to directly recover the thermal power of the exhaust gas. Both models have been validated using experimental data from literature. Two different expander configurations, dynamic and volumetric, has been investigated. Model validations show good agreement with the experimental and literature data, respectively. Moreover, the results highlight that the micro-ORC could achieve a maximum electric efficiency of about 7% at full load with R1234ze(Z). Although at part load the dynamic expander show better performance, the volumetric expander has been selected for the system analysis due to its real suitability for small and micro scale ORC. Combined system results show a maximum enhancement of engine efficiency of about 5%, and better results, in terms of good compromise between electric efficiency and operating range width, has been shown for R1233zd(E). Furthermore, the direct coupling of the PHEX with the exhaust gases allows to have heat exchange evaporator areas below 2 m2 for all analysed fluids.

Advances on a free-piston Stirling engine-based micro-combined heat and power system

As a promising supplement to traditional central electric generation technologies, a distributed combined heat and power (CHP) system is conducive to renewable energy deployment and mitigation of carbon emissions. Among the candidate technologies, the free-piston Stirling engine (FPSE)-based CHP technology is competitive in micro- or small-scale applications. In this work, the performance of a FPSE-based micro-CHP system is improved through a combination of numerical optimization and experimental validation. First, by using a third-order model and thermoacoustic analysis, the impact of regenerator length, displacer moving mass, and force factor of the alternator on the free-piston Stirling generator (FPSG) inside acoustic field, supplied thermal power and exergy loss is studied numerically. The numerical results indicate a rational increase of the force factor, the regenerator length as well as the displacer moving mass is positive for improving the CHP performance. Based on the numerical optimization, the FPSG prototype is updated accordingly, and adequate measurements of the internal acoustic field of the FPSG have been deployed. Then, a series of experiments are conducted to evaluate the CHP performance of the refurbished FPSG prototype. The experimental results show that the highest CHP efficiency reaches 95.7%, the output electric power is 4.03 kW, and the corresponding thermal-to-electric efficiency is 32.2% when the average temperature of supply and return water is as high as 75 °C. Compared with the work before upgrade, the output electric power and CHP efficiency are improved significantly by 39% and 9.4%, respectively. An insight into the impact of the temperature difference between supply and return water indicates that it has a slight impact on electric power generation, especially under higher charge pressure. In contrast, thermal production exhibits an apparent negative correlation with the temperature difference.

Energy Storage Investment and Operation in Efficient Electric Power Systems

We consider welfare-optimal investment in and operation of electric power systems with constant returns to scale in multiple available generation and storage technologies under perfect foresight. We extend a number of classic results on generation, derive conditions for investment and operations of storage technologies described by seven cost/performance parameters, and develop insights on power systems with multiple storage technologies. Simulation of a deeply decarbonized “Texas-like” power system with two available storage technologies shows both the non-existence of simple “merit-order” rules for storage operation and the value of frequency domain analysis to describe efficient operation. Our analysis points to the critical role of the capital cost of energy storage capacity in influencing efficient storage investment and operation.

Influences of Divalent Ions in Natural Seawater/River Water on Nanofluidic Osmotic Energy Generation.

Besides the dominant NaCl, natural seawater/river water contains trace multivalent ions, which can provide effective screening of surface charges. Here, in both negatively and positively charged nanopores, influences from divalent ions as counterions and co-ions have been investigated with respect to the performance of osmotic energy conversion (OEC) under natural salt gradients. As counterions, trace Ca2+ ions can suppress the electric power and conversion efficiency significantly. The reduced OEC performance is due to the bivalence and low diffusion coefficient of Ca2+ ions instead of the uphill transport of divalent ions discovered in the previous work. Effectively screened charged surfaces by Ca2+ ions induce an enhanced diffusion of Cl- ions which simultaneously decreases the net ion penetration and ionic selectivity of the nanopore. As co-ions, Ca2+ ions have weak effects on the OEC performance. The promotion from charged exterior surfaces in OEC processes for ultrashort nanopores is also studied, with an effective region of ∼200 nm in width beyond pore boundaries independent of the presence of Ca2+ ions. Our results shed light on the physical details of the nanofluidic OEC process under natural seawater/river water conditions, which can provide a useful guide for high-performance osmotic energy harvesting.

Research on cost analysis of new power system under dual carbon target

Under the influence of the concept of sustainable development, how to build a clean, low-carbon, safe and efficient modern electric power energy system is the focus of innovative development of new electric power enterprises. Especially after the proposed dual carbon target, new energy in various countries shows an explosive growth trend, and the traditional fossil energy power system begins to transform to a high proportion of new energy power system. Therefore, After integrating previous accumulated experience, China's electric power enterprises study the development path of new energy themed new power system from multiple perspectives. In this paper, based on the understanding of the current development status of new energy in China, according to the framework of new power system planning and development, the actual system cost expenditure is deeply discussed, and the future development trend is clarified based on the dual carbon development goal.

Research on cost analysis of new power system under dual carbon target

Under the influence of the concept of sustainable development, how to build a clean, low-carbon, safe and efficient modern electric power energy system is the focus of innovative development of new electric power enterprises. Especially after the proposed dual carbon target, new energy in various countries shows an explosive growth trend, and the traditional fossil energy power system begins to transform to a high proportion of new energy power system. Therefore, After integrating previous accumulated experience, China's electric power enterprises study the development path of new energy themed new power system from multiple perspectives. In this paper, based on the understanding of the current development status of new energy in China, according to the framework of new power system planning and development, the actual system cost expenditure is deeply discussed, and the future development trend is clarified based on the dual carbon development goal.

Electrical Power Improvement of Grid-tied Photovoltaic Solar System

Abstract: The method that is used to improve performance and electrical power is to use optical reflectors. Optical reflectors improve performance and electrical power, because they increase solar irradiation. CIGS is an acronym for Copper Indium Gallium Selenide. CIGS PV solar module is a second-generation thin-film technology. The system with which optical reflectors are attached is 5kWp. CIGS PV solar system is situated at Al-Mansour factory, Baghdad-Iraq (longitude 44.4°E, latitude 33.3°N and 41m above the sea level). This study improves electrical power, current, performance ratio and array efficiency. All these improvements are done by increasing solar radiance via utilizing optical reflectors (fabricated from aluminum metal). The current system is divided into two parts: improved (PV modules with optical reflectors) and reference part (PV modules without optical reflectors). At 12:00 PM, the largest values of the solar irradiance, electrical power and current for improved and reference PV modules are 1346.1 W/m2 and 981.5 W/m2, 2.308 kW and 1.712 kW,6.01 A and 4.44 A, respectively. At 7.30 AM and 5:00 PM, the largest values of performance ratio and array efficiency of 98% and 14.8%, respectively, are recorded, while the minimum values are at 12:00 pm of 91% and 92.5% and 13.8% and 14.1%, respectively. The largest values of the improved and reference PV module temperatures are 56°C and 50°C, respectively, at the ambient temperature of 21°C. At 7:30 AM, the lowest values of the electrical power, current, solar irradiance and temperatures for the improved and reference PV modules are recorded to be 0.276 kW and 0.267 kW, 0.68 A and 0.65 A, 142.67 W/m2 and 138.44 W/m2, 33°C and 34°C, respectively, at an ambient temperature of 16°C. The maximum increment percentages (gains) for power, current, solar irradiance and module temperatures resulting from using optical reflectors are 34.4%, 35.3%, 37.1% and 6°C, respectively. The current work was achieved under clear sky conditions. The mean increment throughout a day is 24.4%, which is a very good indication of economic feasibility. Keywords: PV solar system, Efficiency, Optical reflector, Grid-connected, CIGS.

Feasibility Study and Techno-Economic Analysis of Solar PV-Biomass Hybrid Power System: A Case Study of Kajola Village, Nigeria

Efficient and sustainable electric power supply is needed for effective healthcare delivery, provision of quality education system, and building of impactful social/human infrastructures. Unrestricted access to reliable and affordable electricity will improve people's welfare and enhance quality healthcare delivery globally. The need to reduce the harmful impact of Greenhouse gas emissions along with its fossil fuel emissions have necessitated the need for the numerous research interests in low-carbon power generation systems. The feasibility and techno-economic analysis of an off-grid Solar Photovoltaic (PV)/Biomass (BG)/Diesel (DG)/Battery (BB) hybrid system for a rural village-Kajola, Nigeria was conducted in this paper. Renewable energy sources (RES) parameters such as irradiation data, biomass resources, and DG parameters were collected from National Aeronautics and Space Administration (NASA)’ database, Ekiti State Ministry of Agriculture and manufacturers’ price lists respectively. The load demand assessment of the area was conducted and analyzed through the use of questionnaires. All the relevant data collected were used as input into the HOMER software. The optimal configuration is the PV-BG-BB combination. The Levelized Cost of Energy (COE) is $0.178/ kWh, with renewable energy fraction (RF) of 100%. This means that nearly all of the energy used by the hybrid system to meet the load is generated from renewable sources. The proposed solar PV/Biomass generator/Battery bank hybrid energy system can supply electricity to the village under consideration at an hourly average of approximately 52.7 kW and with an average daily energy need of 483.71 kWh. The study will serve as a template for all electric power system stakeholders and potential investors on the feasibility and optimal design of hybrid renewable energy system for rural electrification.

Experimental Evaluation of the Thermoelectrical Performance of Photovoltaic-Thermal Systems with a Water-Cooled Heat Sink

A design for a photovoltaic-thermal (PVT) assembly with a water-cooled heat sink was planned, constructed, and experimentally evaluated in the climatic conditions of the southern region of Iraq during the summertime. The water-cooled heat sink was applied to thermally manage the PV cells, in order to boost the electrical output of the PVT system. A set of temperature sensors was installed to monitor the water intake, exit, and cell temperatures. The climatic parameters including the wind velocity, atmospheric pressure, and solar irradiation were also monitored on a daily basis. The effects of solar irradiation on the average PV temperature, electrical power, and overall electrical-thermal efficiency were investigated. The findings indicate that the PV temperature would increase from 65 to 73 °C, when the solar irradiation increases from 500 to 960 W/m2, with and without cooling, respectively. Meanwhile, the output power increased from 35 to 55 W when the solar irradiation increased from 500 to 960 W/m2 during the daytime. The impact of varying the mass flow rate of cooling water in the range of 4 to 16 L/min was also examined, and it was found that the cell temperature declines as the water flow increases in intensity throughout the daytime. The maximum cell temperature recorded for PV modules without cooling was in the middle of the day. The lowest cell temperature was also recorded in the middle of the day for a PVT solar system with 16 L/min of cooling water.

A Numerical Analogy of Improving Efficiency for the PVT System in Bangladesh

Mathematical modeling of a three-dimensional PVT system is considered and solved using the FEM. Numerical simulation is applied to explore the influence of solar irradiance on the thermal energy, electrical power, and total efficiency of this system. Water is considered HTF. The solar irradiance, inlet fluid mass flow rate, ambient temperature, and partial shading are all chosen in the range of 200-500 W/m2, 30-180 L/h, 10-37 °C, and 0-30%, accordingly based on the weather condition of Bangladesh. The effects of irradiance, fluid flow rate, ambient temperature, and partial shading on temperatures of cell and output fluid, electrical power and thermal energy, electrical efficiency-thermal efficiency, and total efficiency of this system are examined. Numerical results show that increasing each 100 W/m2 solar irradiance enhances the cell and outlet temperatures and electrical and thermal energy by 2.17 and 0.54 °C and 20.7 and 113.3 W, respectively, and devalues the electrical, thermal, and overall efficiencies approximately 0.17, 0.67, and 0.83%, respectively. The cell and output water temperature reduce almost 0.6 and 0.83 °C, respectively; electrical and thermal energy rise by 0.30 and 3.07 W, respectively, and the electrical, thermal, and overall efficiencies escalate about 0.04, 0.4, and 0.44% for every 10 L/h mass flow rate increment. Due to each 10 °C increment of ambient temperature, cell and output water temperature increase 1.7 °C and 0.05 °C, electrical energy decreases to 0.9 W, thermal energy increases to 9.89 W, and electrical efficiency reduces about 0.1%.

A novel liquid metal MHD enhanced Closed-Brayton-Cycle power generation system for hypersonic vehicles: Thermodynamic analysis and performance evaluation with finite cold source

Closed-Brayton-cycle (CBC) is a potential thermodynamic cycle for high-power dynamic electricity generation on hypersonic vehicles, but finite cold source onboard limits its power level. This study presents a liquid metal MHD (LMMHD) enhanced CBC power generation system and exhibits its theoretical advantages through thermodynamic analysis. The influence of cold source temperature rise, turbine inlet temperature and LMMHD conversion efficiency on system performance is investigated by a zero-dimensional power optimization model, and the electric power and power generation efficiency between LMMHD enhanced CBC and standalone CBC are compared. Results indicate that LMMHD enhanced CBC can theoretically meet the demand for megawatt-class power generation on hypersonic vehicles, the electric power per unit fuel mass flowrate of which can reach 637.84 kW. High-temperature liquid metal and well-designed LMMHD generator are extremely essential to improve the turbine inlet temperature and LMMHD conversion efficiency. Compared with standalone CBC, the electric power increased percentage of LMMHD enhanced CBC is as high as 92.44 %. This paper provides primary performance evaluation for LMMHD enhanced CBC, the key technical issues of which, including the LMMHD generator structure design, mixing and separation process optimization, will be the focus in our next work.

Performance analysis of vortex tube-thermoelectric system in gas stations

At natural gas pressure reducing stations, gas first enters a water bath heater to boost its temperature slightly, and after leaving the heater, it enters the throttle valve to reduce its pressure. This method has two major drawbacks, which are the consumption of natural gas in the heater and the excessive loss of exergy in the throttle valve. The pressure of natural gas can be reduced by using a vortex tube and converting it into hot and cold currents, and then generating electricity by directing these currents to thermoelectric generators (TEGs). Investigation of energy, exergy and environmental performance of the hybrid vortex tube-TEG system and optimization of its performance for the working condition of Kermanshah pressure reducing station is the subject of the present study. The cold mass fraction (CF) and efficiency of vortex tube are considered as decision variables. Moreover, annual average first-law efficiency (ηI-TEG), annual average second-law efficiency (ηII-TEG) and annual total electric power generated by the TEGs (Pout) are considered as optimization target functions. The results of genetic algorithm based three-objective optimization revealed that the specifications of the optimal system are: vortex tube efficiency = 0.36967, CF=0.95598, ηI-TEG=0.03442, ηII-TEG=0.04544, Pout=42770.58 kW and amount of CO2 mitigation per annum = 8.55 tons.

Effectiveness of the Speed Reduction Strategy on Exhaust Emissions and Fuel Oil Consumption of a Marine Generator Engine for DC Grid Ships

Recent developments in power electronics, energy storage systems, and renewable energy; increased market demands for more efficient and cleaner electric power to meet stricter environmental regulations; and development in gigawatt (GW)-class DC (direct current) transmission systems for transmission of greater power over longer distances than similar alternative current (AC) systems, have supported the development of the DC grid, making it a promising solution for both the onshore and offshore industries. This paper presents an experimental study on the effectiveness of an engine speed reduction strategy on exhaust gas emission and fuel consumption when applied to a 4-stroke generator engine equipped with a cam-driven plunger diesel injection system. The experiments were performed on an 8-cylinder V-type 4-stroke generator engine installed in the MASTC laboratory, which is the only demonstration testbed for the ship’s electric propulsion system in Korea. Experimental results showed that fuel consumption decreased, but emission mass fraction in exhaust gas increased when maintaining engine power while reducing engine speed. This study has shown economic benefits in reducing fuel consumption, but incurred penalties for the emission performance of 4-stroke generator engines equipped with cam-driven plunger diesel injection systems when applying the engine speed reduction strategy.

Transactive energy revolution: Innovative leverage for reliable operation of modern energy networks—A critical review

The electric industry is developing towards a more efficient, reliable, and resilient electric power network. In this way, utilizing distributed energy resources (DERs), especially renewable DERs (RDERs) are a paradigm change. DERs offer many advantages in power systems, including transmission loss reduction, environmental benefits of RDERs, and enhancement of security, reliability, and resiliency of the network. However, high penetration of DERs increases uncertainty and challenges the efficient and reliable operation of the power system. This paper provides a thorough review of the transactive distribution platform which is essential to address the aforementioned challenges. This distribution platform includes a transactive distribution system operator providing a seamless and coordinated control to dynamically balance supply and demand and follow uncertain generations of RDERs. Indeed, this review paper highlights the capability of transactive energy (TE) by considering its key aspect in providing energy sharing opportunities for the integration of DERs into smart grids (SGs). TE is acombination of economic and control methods that enable optimum, reliable, sustainable, and efficient operation of SGs. Furthermore, a fully transactive framework offers more choices for DERs to control and manage the energy transactions in the retail market, as well as improves the inter operability among various market players.

Pengaruh Variasi Sudut Kemiringan Dan Debit Air Terhadap Daya Dan Efisiensi Turbin Air Vortex

<p><em>The vortex turbine is a moving turbine using artificial whirlpools that will then be converted into alternate energy turbines on the axis. The purpose of this study is to find out how high the Angle of skeleton tilt and dissipation of water affects the electricity and efficiency generated by vortex's water turbines. This study is using experimental methods. The study involves a few steps by preparing water turbines, sets up tools, data retrieval, and data analysis. The research free variable is a variant of the Angle of the skeletal tilt at 0, 5, 10 and a discharge of water at 6.34 l/s, 7.41 l/s, and 8.29 l/s. The bound variables of research are vortex's type of electric power and electricity efficiency. The research control variable is vortex turbine blade and vortex water turbine. The research instrument used is multimeter-based arduino, flowmeter-based arduino, tachometer, bow and digital balance. Data analysis techniques using quantitative descriptive analysis. The test conducted based on variations of water discharge at 6.34 l/s, 7.41 l/s, and 8.29 l/s and skeletal variant turbine gradient at 0, 5, and 10 of the power and efficiency of the turbines generated. Research shows that the maximum data of electrical calculation is obtained on water-discharge at 8.29 l/s with a tilted point 10 which was 10.3 watts, while the maximum efficiency data is obtained on water-diacharge at 8.29 l/s with a tilted point 10 which was 42.9%.</em></p>

An innovative clustering technique to generate hybrid modeling of cooling coils for energy analysis: A case study for control performance in HVAC systems

Despite past studies, no comprehensive models or empirical correlations cover all aspects of performances of cooling coils under different flow regimes (laminar, transition, and turbulent). Moreover, the cooling coil is characterized by a highly nonlinear dynamic subject to multiple inputs, coupling between the latent and sensible heat transfer modes, uncertain disturbances, and strong dependence of the overall heat transfer coefficient on the flow type, all causing significant challenges when it comes to modeling. Therefore, a hybrid layer structure model was adopted in this study to overcome these challenges. The new approach used two different optimization methods, Neural Networks' Weights and Takagi-Sugeno (TS) fuzzy, and the hybrid layers tuned by the Gauss-Newton algorithm (GNA). The proposed model covered three types of fluid flow to represent the dynamic behavior of the water-side and air-side heat transfer coefficients, each of which was divided into seven clusters and had its unique TS consequence. This study also administered meaningful fitness tests in the responses of the eleven independent variables that serve as its inputs. Furthermore, its application shows the control performance saving more than 44% of HVAC system energy. Based on the results, it was concluded that the proposed model is suitable for estimating energy and cost savings for electric power and water flow rate efficiency. In addition, the response of all types of output flow can be evaluated when changing eleven independent variables that are manipulated by three different controllers.

Temperature and Humidity Control Device In The Server Room PT.BFI Finance Tbk. Karawaci Based on Internet Of Things (IoT)

The monitoring system for server room temperature and humidity at PT.BFI Finance which can increase the efficiency of electrical power using Arduino. At this time, technological advances are very fast, one of which is the presence of the Internet of Things, therefore the server room monitoring system at PT.BFI Finanace will use a temperature and humidity measuring device with an Arduino Uno microcontroller, Ethernet shield, Arduino Nano, buzzer, fan and the DHT22 sensor, which is able to overcome the weaknesses of existing server room monitoring. The purpose of this research is to make a temperature and humidity measuring device in the server room as a monitoring tool. The result of this research is a monitoring system for temperature and humidity conditions in the server room with a device whose temperature and humidity values ??will be stored in the MYSQL database, then displayed on a web application that will assist officers in monitoring the server room.

Uncertainty Estimation of Luminous Flux for LED Lamps Due to the Control of Electric Power

Electrical power efficiency has been of interest to both energy providers and consumers as it plays a pivotal role in our daily life. The voltage fluctuation is a significant issue with power quality since it has a substantial influence on electronic devices in addition to its economic impact. Several contributions have been dedicated to estimating the uncertainty in luminous flux including various parameters; however, most of them have been focused on traditional light sources such as incandescent lamps. One of the main parameters that have not been considered is the uncertainty in electric power due to voltage instabilities. In this study, the effect of regulating the electric power on the luminous flux and its combined uncertainty for different brands of LED lamps were explored. The LED lamps currently available in the Egyptian market have been tested according to their photometric and electric parameters. Three different brands labeled E, T, and V have been chosen with nominal power of 9 and 15 Watt. The experimental testing of such lamps showed that the power factors have a considerable effect on the combined uncertainty of the overall luminous flux.

Direct mapping of edge states in bilayer zigzag phosphorene nanoribbons into a SSH ladder model and optimizing their thermoelectric performance via edge state engineering

We theoretically investigate the thermoelectric properties of zigzag bilayer phosphorene nanoribbons (ZBPNR). We first, draw an analogy between the extended Su-Schrieffer-Heeger (SSH) ladder and ZBPNR edge states and obtain their corresponding band structure and wave functions analytically. Then, by applying the energy filtering method, we show that the electric power and thermoelectric efficiency of the ZBPNRs can be improved remarkably in the presence of mid-gap edge states. We also argue how to engineer the edge modes to further optimize thermoelectric power and efficiency of the system by applying periodic point potentials at the boundaries.

Stability tool for electric power systems with a high penetration of electronic power converters

The increasing use of electronic converters is making possible the development of more sustainable, efficient, and reliable electric power systems, but it is also introducing new challenges that need to be addressed. Power system stability is one of them since the converter multiscale coupling between control loops and the mutual effects of multiple converters make the traditional approaches and specialized software available not fully adequate. In this context, this paper presents a software tool called CSTEP capable of carrying out small- and large-signal stability analysis for electric power systems strongly dominated by electronic converters. By utilizing the tool description, the paper provides the reader with a systematic methodology to obtain the system dynamic representation, and with some software tools for the analysis of the large and small-signal stability. Finally, the validity and functionality of CSTEP have been tested with the implementation of three use cases: a simple ac use case to illustrate the application of the system algorithm step by step, an IEEE 5-bus use case to validate the tool with already established commercial software and a more realistic system based on a medium voltage CIGRÉ benchmark to highlight the potential applications of the tool. The results show that, unlike existing tools that simplify or neglect the electric part of the grid (filters, line impedances, etc.), CSTEP can predict power system instabilities caused by the interactions of fast control loops of electronic converters with the electric part.