Calculation Of Energy Efficiency Research Articles

Application of exergy analysis in understanding the performance of a coal-fired steam power plant (120 mw) with single reheat and regenerative configuration

In the present paper, a rigorous analysis of a sub-critical steam power plant (120 MW) with reheating and regenerative configuration is presented, using energy and exergy analysis. The total work output from the power plant is 121.80 MW, which is close to the real value of 120 MW. The calculated energy efficiency of the steam power plant is 34.7%, while its exergy efficiency is 32%. In addition to it, energy analysis introduces the condenser as a major source of heat loss, on other hand, exergy analysis introduces the boiler as a major source of exergy destruction. Further to understand the effect of main steam temperature, reheating temperature and condenser pressure on the power plant, a parametric study is being conducted.

INTEGRATED APPROACH TO ENERGY EFFICIENT BUILDING DESIGNING BASED ON BIM

Problem statement. The design of energy efficient buildings requires compliance with a number of criteria. The use of energy efficient constructions and building materials, the use of energy efficient engineering solutions and high performance equipment can more than halve a building's resource consumption. But it is important to select and define the characteristics individually. A real estate object must therefore, first of all, be designed correctly. Calculated designs, reasonably selected building materials and correct calculations from thermal engineering calculators do not guarantee obtaining a heat-insulating and vapor-insulating envelope without gaps. Due to the complexity of the construction object, it is problematic to identify thermal bridges and take into account weak points without an integrated approach to the design of the future building. The climate, geographical location and terrain must also be taken into account. In order to carefully select the optimal design solution, it is necessary to take a large array of data related to energy efficiency indicators. In classic design systems, such information is not displayed or analyzed. It is very difficult to assess the energy efficiency of the project. The technology of building information modeling, or BIM, makes it possible to radically simplify the task of designing energy efficient buildings. The purpose of the article is to substantiate the use of modern programs based on VIM technologies at the stage of energy efficient building design, to determine the criteria for selecting a software complex that will allow you to perform building simulation, calculate energy efficiency indicators, analyze thermal bridges, visualize the results, and issue a package of working documentation within the framework of one program. Demonstrate a highly detailed three-dimensional model of the building enriched with maximum information: data on the thermal conductivity of building materials and technical characteristics of equipment.

A Brain-Inspired ADC-Free SRAM-Based In-Memory Computing Macro With High-Precision MAC for AI Application

In this brief, an ADC-free SRAM-based IMC macro is proposed, which enables energy-efficient and high-precision MAC operation by brain-inspired computing. We identify two key features that support IMC macro to achieve high energy efficiency and high precision MAC calculation. First, the temporal-coding spiking neuron circuit is used to replace the analog-to-digital converter (ADC) to achieve high-efficiency data conversion. Second, the digital adder tree logic eliminates the cost of moving partial sums between PEs and increases the parallelism of the calculations. The mixed-signal SRAM-based IMC macro is designed for processing artificial intelligence (AI) algorithms with reconfigurable precisions based on bit-wise input and weight. In an experiment, the proposed SRAM-based IMC macro with an area of 3.41 mm2 was designed in 0.18 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu {\mathrm{ m}}$ </tex-math></inline-formula> CMOS technology. Post-layout simulation results indicate that the 16Kb IMC macro achieves 10.8-13.5 TOPS/W with 4-b inputs, 4-b weights, and 14-b MAC-value outputs.

The Environmental Feasibility of Decentralised Solar Ammonia.

Intense efforts have been devoted to developing green and blue centralised Haber-Bosch processes (gHB and bHB, respectively), but the feasibility of a decentralised and sustainable scheme has yet to be assessed. Here we reveal the conditions under which small-scale systems based on the electrocatalytic reduction of nitrogen (eN2R) powered by photovoltaic energy (NH3-leaf) could become a competitive technology in terms of environmental criteria. To this end, we calculated energy efficiency targets based on solar irradiation atlases to guide research in the incipient eN2R field. Even under this germinal state, the NH3-leaf technology would compete favourably in sunny locations relative to the business-as-usual production scenario. The disclosed sustainability potential of NH3-leaf makes it a strong ally of gHB toward a non-fossil ammonia production.

ANALYSIS OF APPROACHES TO DETERMINING THE QUANTITY OF THERMAL ENERGY FOR THE NEEDS OF HOT WATER SUPPLY IN THE ENERGY CERTIFICATION OF BUILDINGS

In Ukraine, at the legislative level, as part of the implementation of EU Directives, mandatory energy certification has been introduced for certain types of new and reconstructed buildings. In addition, in order to receive financing from various investment funds and the possibility of participating in state or local thermomodernization programs, it is necessary to perform their energy audit and justify energy-saving measures, assess the energy efficiency class. In Ukraine, there is a complex of regulatory acts, methodical documents, construction norms and standards in the field of energy certification, which is constantly updated. The national methodology for calculating energy efficiency indicators has been passed and the by-laws have changed several times, in particular, in the part of accounting for energy consumption for hot water supply, which in turn affected the energy efficiency class. The article evaluates the influence of different approaches to the calculation and accounting of additional revenues from hot water pipelines on the example of a residential multi-story building in Kyiv. As part of the research, a detailed energy survey was carried out using instrumental and analytical methods, the geometric, thermal and energy characteristics of the building were specified, and a set of measures to increase the level of energy efficiency was proposed. As part of the research, a detailed energy survey was carried out using instrumental and analytical methods, a calculation model was formed and a series of calculations was performed. The impact on the specific energy demand, total energy consumption and energy efficiency class of the existing building of changes in the regulatory framework, the features of taking into account utilized heat losses, the number of consumers is shown.

Cavity-shaped direct solar steam generator employing conical helical tube for high-temperature application: Model development, experimental testing and numerical analysis

Concentrating solar thermal technologies are drawing more attention since it can substantially contribute to a carbon-neutral society. The solar receivers are essential in this technology to convert solar energy efficiently into thermal energy. Moreover, high-temperature steam generation is the promising application for concentrated solar power plants or industirial processes. Therefore, the direct solar steam generator has been gaining more attention due to its advantages of low operation and maintenance costs. Most solar steam generator designs consist of a tube with helical configuration because of its high heat exchange performance and compactness. However, only few studies address solar steam generators with conical helical tubes. Thus, both experimental and simulation data of this design are scarce. This paper shows the successful development and experimental testing of a solar steam generator with a conical helical tube. The experimental results proved that the developed solar steam generator can produce high-temperature steam of 600 °C at an inlet pressure and mass flow rate of 150–200 kPa and 2.5 kg/h, respectively. The overall calculated energy efficiency (thermal and optical efficiency) was 60–62%. In addition, a coupled 1D-3D numerical model was implemented to analyze the solar steam generator’s performance. The model consists of a 3D cavity heat transfer model and a 1D two-phase fluid flow model. The numerical analysis demonstrated the ideal generator’s performance (energy efficiency of 68–69%) and the great impact of convection in the heat losses (50% of the total energy losses). Although more research of the convection is required, the presented results provide a basis for designing further, upscaled solar steam generators employing conical helical tubes.

High Purity Hydrogen Separation with HT-PBI Based Electrochemical Pump Operation at 120 °C

Electrochemical Hydrogen Pumps (EHP) provide a unique highly efficient means of separating and compressing hydrogen with continuous steady-state operation. In this paper, we demonstrate the performance of a commercially available, polybenzimidazole (PBI) membrane based platform as a benchmark for ultra-high efficiency performance. A primary gas mixture of CO2 and H2 with a ratio of 4:1 respectively was selected to demonstrate the performance of EHPs with near theoretical Faradaic efficiency with negligible CO poisoning due to reverse water gas shift reaction (RWGS). It was found that humidification of the feed gas at room temperature improved polarization performance while also improving energy efficiency, thus reducing the need for a tightly controlled relative humidity of feed gas. A new perspective on EHP energy efficiency calculation methodology is also provided by including the cell heating requirement in the calculation. In this manner, an overall improvement to the energy efficiency of nearly 20% was realized by dropping the cell temperature to 120 °C while paying no significant penalty to electrochemical performance. Nearly 99.99% pure H2 and 99.93% pure CO2 were produced with a hydrogen yield of 99.34%.

Solar-driven polymer electrolyte membrane fuel cell for photovoltaic hydrogen production

The globe will be obliged to discover and investigate alternate energy sources, as at the current pace of use, fossil fuels will cause an energy catastrophe in the coming future. The energy plight can only be minimized or altogether avoided if the energy industry works to develop innovative methods of extracting energy from non-conventional sources such as solar, geothermal, ocean-thermal, biomass, hydro and wind energy. Fuel cell technology is one such renewable energy technology that is proliferating all over the world. Fuel cells will be an important future source of power and energy generation. Various advantages of fuel cells have led many researchers to work towards this technology. Different types of fuel cells are used for energy and power generation. Among all other contenders, Polymer Electrolyte Membrane Fuel Cell (PEMFC) has wide acceptance worldwide due to certain innate advantages. The current study aims to know about the characteristics and primacy of the PEM fuel cells, which involves both experimental and theoretical observations based on Hydro Genius Professional - a laboratory scale model. The experiments were performed to investigate the characteristics of a fuel cell through renewable energy-driven power sources, mainly solar power. However, the last part of the article deals with a solar panel's voltage-current and power-current characteristics. Further, the optimization of parameters for extracting maximum power from the circuit is also analyzed. The research further includes the determination of Faraday and energy efficiencies for an electrolyzer and a fuel cell system, which are around 95.75% and 98%, for Faraday efficiency calculations and 90% and 45% for energy efficiency calculations in an electrolyzer and fuel cell system respectively. The research contributes to a better understanding of renewable fuel cell technology and elaborates on the practical applications of hydrogen generation using photovoltaic systems and their integration with fuel cell systems. The study will also concentrate on fuel cell technology's environmental benefits and green innovation upfront.

Analysis and optimization of acceleration model in coaxial plasma gun in pre-fill mode

Snowplow model is the main method to describe the acceleration process of coaxial plasma gun in the pre-fill mode, which can directly give the analytical expression of plasma velocity versus time. So it has become an important reference in designing the device structures satisfying the requirements for different applications. Through measuring the current, magnetic and optical signals, the characteristics of current during the discharge and the motion of plasmoid are investigated. The variation of discharge current with time is close to the damping sine curve, which is an underdamping solution of RLC equivalent discharge circuit. The measured current in lieu of the sine one is used to calculate the theoretical velocity so as to eliminate the error of magnetic pressure. The variation of plasma velocity with discharge voltage and chamber pressure are consistent with those obtained by solving the equation of plasma motion under snow plough model, but the acceleration process is another story. At the initial stage of the discharge, owing to the low sweep efficiency, the plasma is accelerated to a higher velocity than the predicted one, the increase of voltage and the decrease of pressure further enhance the effect. With the extension of the acceleration distance, owing to the friction resistance between plasma and electrodes, the acceleration slows down and the velocity starts to fall below the predicated value, the saturation of plasma velocity at the nozzle is found. The friction resistance term is added to the equation of plasma motion. Compared with the deviation range of 26.8%–53.6% of the existing model, the differences between the theoretical speed and the measured speed under different voltages and pressures are in a range of 3.1%–8.4% after adding the friction resistance term into the equation of plasma motion. The optimization of snow plow model greatly improves the accuracy of velocity prediction, which can provide an effective reference for designing device structure and calculating energy efficiency.

Improving the energy efficiency of wood harvesting in Finland

To address the issue of climate change, the EU’s climate and energy framework has set targets to improve energy efficiency. Reducing greenhouse gas (GHG) emissions requires higher energy efficiency in the wood supply of forest industries. The aim of the study was to clarify the energy-efficiency baseline for wood-harvesting operations, define useful measures and follow up the total fuel consumption and resulting emissions. The results indicated that wood-harvesting entrepreneurs have a positive attitude towards energy efficiency. The fuel consumption of wood-harvesting machines was the lowest for the final fellings, while in first thinnings, the consumption was highest per cubic metre harvested. The average cubic metre-based fuel consumption and GHG emissions in respect of wood harvesting were more than double in the first thinning compared to the final felling. Better allocation of harvesting machines could reduce fuel consumption and GHG emissions while improving work efficiency. Hour-based fuel consumption is most affected by machines’ engine power and wood-harvesting conditions of forest stands. Fuel consumption per cut cubic metre is affected by wood-harvesting conditions and machine units. The calculated energy efficiency was highest in final fellings. A more significant factor than fuel consumption (input) is the amount of harvested wood (output) in the energy-efficiency equation. Energy efficiency can also be improved by operator education. Trucks which are used for harvesting-machine relocation have a significant impact on wood-harvesting operations' total fuel consumption and emissions. It is therefore essential to minimise the number of relocations and operational and resource planning should be developed. In the future, the examination of fuel consumption and GHG emissions should be extended to the entire wood-harvesting chain, including long-distance transportation and timber trade, and for example the effect of operator should be investigated in more detail.

Study of the Energy Efficiency of an Urban E-Bike Charged with a Standalone Photovoltaic Solar Charging Station and its Compliance with the Ecuadorian Grid Code No. ARCERNNR – 002/20

E-bikes are an emerging sustainable means of transportation, if adopted massively, they can help face the challenges of human mobility in urban centers worldwide. In Cuenca, Ecuador, the local government built cycle routes (13.47 km) connecting strategic points to facilitate and encourage sustainable mobility. However, the effective implementation of the electromobility strategies at a large scale entails impacts on the power grid, like the increase in the energy demand and the possible decrease of the energy quality due to the harmonic distortion that characterizes the battery's charging current. This research aims to obtain a primary input to evaluate such impacts through an energy efficiency study of an urban e-bike charged by a standalone solar photovoltaic charging station implemented in the Microgrid Laboratory of Universidad de Cuenca. The methodology includes the experimental characterization of the battery's charging regime, the vehicle's energy efficiency calculation, and the evaluation of its compliance with Ecuadorian grid code No. ARCERNNR – 002/20. Results show that the battery's charger performs a charging regime standardized by German regulations, delivering 92% of charge in 4.82 hours. The e-bike's calculated average energy efficiency is 2.18 kWh/100 miles or 73.77 m/Wh, and a fuel economy of 1545.1 MPGe. Finally, the magnitude of the first four odd harmonic components and the total harmonic distortion of the charging current exceeds the limits established by the grid code in force.

ИССЛЕДОВАНИЕ МОДЕЛИ ДИССОЦИАЦИИ ГАЗОГИДРАТА В ПЛАСТЕ ПОД ДЕЙСТВИЕМ СВЕРХВЫСОКОЧАСТОТНОГО ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ

The article presents a numerical study of the gas hydrate dissociation model in a reservoir under the action of microwave electromagnetic radiation at 400 MHz, 1 000 MHz, and 2 450 MHz. The decompo-sition of gas hydrate under this influence is faster at lower values of the reservoir’s initial hydrate saturation. The effects of 1 000 MHz and 2 450 MHz frequencies are much stronger than those of 400 MHz. The study shows that during heating times higher than 400 hours, 1 000 MHz frequency radiation electromagnetic heating is more efficient than that of 2 450 MHz frequency. Using the proposed mathematical model, it is possible to determine the optimal frequencies of the radiation source at a given time of heating the reservoir of a particular field. Moreover, the resulting calculation of energy efficiency (EROI ≥ 10) of this method for gas hydrate-extracted gas proves its competitiveness when compared to traditional methods of thermal impact on the reservoir.

Seafarers Involvement in Implementing Energy Efficiency Operational Measures in Maritime Industry

The Fourth GHG Study 2020 of the International Maritime Organization (IMO) reported that 2.89% of total global anthropogenic CO2 emissions had been emitted by international shipping. IMO's initial strategy is to set carbon intensity goals of at least a 40% reduction in CO2 emissions per transport work by 2030, and a 70% reduction by 2050 must be met. This has led IMO to introduce guidelines for calculating energy efficiency in both the design and operation phases using the Energy Efficiency Design Index (EEDI), the Ship Energy Efficiency Management Plan (SEEMP), the Energy Efficiency Existing Ship Index (EEXI), and the Carbon Intensity Indicator (CII). In the decade between 2008 and 2018, the energy efficiency of international shipping operations advanced by one-third. By adopting energy efficiency design and operational measures and introducing innovative technologies, many shipping companies worldwide reported remarkable financial and environmental benefits by saving fuel on every voyage. Ships are operated by ashore technical managers and aboard crewmembers; thus, they are directly involved in implementing energy efficiency operational measures. Therefore, the scope of this study is only limited to ashore technical managers and aboard ship crews only. This study has found that Master and Deck Crews are directly involved in implementing the ship's navigation and port operation-related EE measures. In contrast, the Chief Engineer and Engine Crews are directly involved in all ships’ propulsion, power generation, and management-related operational EE measures to implement onboard ships. Since the ashore managers supervise the ship's Master and Chief Engineer, they have reasonable control in every aspect of the fleet's energy efficiency operations, from navigation to port operations and ship's propulsion to power generation and management.

A 1.45-pJ/b 16-Gb/s Edge-Based Sub-Baud-Rate Digital CDR Circuit

A 16-Gb/s edge-based sub-baud-rate digital clock and data recovery (CDR) circuit is presented. By using the proposed edge-based sub-baud-rate technique and a passive high-pass filter, the complementary clocks are used to save the power. To improve the jitter tolerance, the intrinsic delay of the high-pass filter is compensated by using compensation delay cells. The proposed sub-baud-rate CDR circuit is fabricated in 40-nm CMOS technology. Its active area is 0.0376mm2 and the power is 23.2mW for a supply of 1.2V at the data rate of 16 Gb/s. The calculated energy efficiency of this CDR circuit is 1.45 pJ/b.

A novel flexible multi-effect absorption system for the production of controllable quantities of power, heating, cooling, and desalination

In this work, a modified flexible multi-effect absorption system has been proposed to produce controllable, in quantity and type, products of cooling, power and fresh water. By “controllable” it is meant that the modified system is able to produce one, two, or three types of products, combined or separated and in any ratio, according to the needs. Heating may be considered as the fourth controllable product since it is the already available source. The essence of the current system lies in its flexibility as it is easily able to change the type and amount of the products. The system is studied under different hot source temperatures and different mass fractions. The results show that when the system is operating with equal mass fractions, it can produce cooling capacity, fresh water rate, and electric power up to 21.1 kW, 38 L/h, and 0.58 kW, respectively. In this case, the calculated energy efficiency, exergy efficiency and GOR are 71.6%, 26.8%, and 3.524, respectively.

Data-Driven Approach for Estimating Power and Fuel Consumption of Ship: A Case of Container Vessel

In recent years, shipborne emissions have become a growing environmental threat. The International Maritime Organization has implemented various rules and regulations to resolve this concern. The Ship Energy Efficiency Management Plan, Energy Efficiency Design Index, and Energy Efficiency Operational Indicator are examples of guidelines that increase energy efficiency and reduce shipborne emissions. The main engine shaft power (MESP) and fuel consumption (FC) are the critical components used in ship energy efficiency calculations. Errors in ship energy efficiency calculation methodologies are also caused by misinterpretation of these values. This study aims to predict the MESP and FC of a container ship with the help of data-driven methodologies utilizing actual voyage data to assist in the calculation process of the ship’s energy efficiency indexes appropriately. The algorithms’ prediction success was measured using the RMSE, MAE, and R2 error metrics. When the simulation results were analyzed, the Deep Neural Network and Bayes algorithms predicted MESP best with 0.000001 and 0.000002 RMSE, 0.000987 and 0.000991 MAE, and 0.999999 R2, respectively, while the Multiple-Linear Regression and Kernel Ridge algorithms estimated FC best with 0.000208 and 0.000216 RMSE, 0.001375 and 0.001471 MAE, and 0.999999 R2, respectively.

The puzzle of energy efficiency in Turkey: combining a multiple criteria decision making and the time series analysis

ABSTRACT Enhancing energy efficiency is important for sustainable economic development and environmental-related issues such as carbon emissions. Therefore, measuring energy efficiency is crucial for countries to achieve economic and environmental objectives. In this study, we utilize the TOPSIS method with the intent of monitoring the energy efficiency of Turkey from the 1980 to 2018 period. Several variables such as renewable and nonrenewable energy consumption, GDP, labor force, and capital stock are employed in calculating energy efficiency scores. Thereafter, we analyze the long-term, symmetric and asymmetric effects of some contextual variables such as capital stock-labor force ratio, renewable energy consumption-total energy consumption ratio, and carbon emission-total energy consumption ratio on energy efficiency via ARDL and nonlinear ARDL models. Results from the linear model indicate that an increase in the renewable energy consumption-total energy consumption ratio and capital stock-labor force ratio increase the energy efficiency. In contrast, an increase in the carbon emission-total energy consumption ratio decreases it. The nonlinear ARDL model, on the other hand, signals asymmetric effects in the long-run but not in the short-run.

An analysis of energy efficiency of the Pearl River Delta of China based on super-efficiency SBM model and Malmquist index

With the rapid growth rate of China’s economy, the extensive pattern of economic growth of “high energy consumption and low output” has magnified the constraints of energy issues on China’s economic development and environmental protection, which highlights the importance of improving energy efficiency. As one of the three major economic zones in China, the Pearl River Delta region also faces high energy consumption and pollution emissions while developing at a high speed. Hence, improving the energy efficiency of the Pearl River Delta region is needed, as it not only is conducive to driving its development of the surrounding green economy, but also promotes the subsequent sustainable economic development. However, there are few literatures on the calculation and analysis of energy efficiency in the Pearl River Delta, and lacking a systematic analysis of input–output index system of energy efficiency measurement. Therefore, this paper calculates the energy efficiencies and the Malmquist indexes based on the panel data of the nine cities in the Pearl River Delta from 2005 to 2019 through super-efficiency SBM model and Malmquist index method by using MAXDEA and MATLAB software. The result illustrates that all regions in the Pearl River Delta except Guangzhou and Shenzhen show obvious energy inefficiency, which is mainly caused by the imbalance between technical efficiency and scale efficiency. Based on the calculation results, this paper gives some relevant suggestions for the further approach of energy reform in the Pearl River Delta according to the calculation results.

Techniques For Reducing Energy And Delay For Data Aggregation In Wireless Sensor Networks

WSN have many applications in different fields like medical, military, health and agriculture, etc., due to its data sensing and gathering abilities to Base station. The main issue in wireless sensor network is energy efficiency under consideration of QOS parameter like delay and security. Many of techniques have been proposed in literature but few work on energy efficient network with QOS. Due to lack of prior research in this area of study, this research will optimize the existing result in manner of giving efficient energy mechanisms and will also provide QOS as well as reduction of delay. It is very important to calculate energy efficiency and data transmission rate in wireless sensor networks because it is widely used in every field of life, especially when we are talking about medical, military and navigation system. After identifying main issues, this research will focus on energy efficiency and delay reduction. But other factors like security and average transmission time is not fully focused.

Efficiency estimation of wheel automobile propulsion unit

Problem. Energy efficiency of an automobile is a characteristic of rational use of engine power and consumption of energy sources. The rational use of engine power is the implementation of the maximum dynamics of an automobile at the lowest energy consumption (power). To date, the problem of estimating the efficiency of the automobile wheel propulsion unit is one of the most relevant in modern engineering. Therefore, there is an urgent need to optimize the ability to assess the energy efficiency of automobile by obtaining a mathematical model of the efficiency of the wheel propulsion unit for further rational design of automobiles according to energy efficiency criteria. Goal. The aim of the work is to increase the ability to assess the energy efficiency of the automobile by obtaining a mathematical model of the efficiency of the wheel propulsion unit. Methodology. Analytical, mathematical and research methods were used to develop a model for estimating the efficiency of the automobile wheel propulsion unit. Results. The results of the study allowed to determine that with an increase in the maximum torque on the clutch, there is an increase in the efficiency of the latter. The obtained mathematical model of the instantaneous power consumption factor for the movement of the driven wheel allows to increase the accuracy of estimating the energy efficiency of cars. The obtained analytical expression of the estimation of the instantaneous power consumption factor of the wheel propulsion unit allows to carry out rational design of automobiles on the criterion of energy efficiency in the future. Analysis of the obtained expression showed that with increasing number of drive wheels, the efficiency of the wheel propulsion unit also increases. Originality. The originality is in obtaining a mathematical model of the efficiency of the wheel propulsion unit of automobile, which will further help to select the rational parameters of the chassis and refine the calculation of energy efficiency of automobiles. Practical value. The practical value of the study is to provide practical recommendations for improving the ability to assess the energy efficiency of the automobile by obtaining a mathematical model of the efficiency factor of the wheel propulsion unit.