Calculation Of Energy Efficiency Research Articles

Improving Net Energy Efficiency of Dimethyl Ether Production Process by Methanol Dehydration

Dimethyl ether (DME) is a source of fuel that produces clean energy for the future. Methanol can be used as a raw material for the manufacture of DME as a natural gas that is treated for synthesis. This paper evaluates how to improve net energy efficiency in DME production and how to review the net energy efficiency calculations in DME production. Methods used for production of DME are methanol dehydration, thermodynamics examination, also improving the net energy efficiency of DME with the addition of the heat exchanger (E-100), the addition of a heater (E-104) before entering a column (T-102), and moved the mixer position before the heater (E-100). By modifying the addition of a heat exchanger (E-100), heater (E-104), and changing the position of the mixer in DME production, it has been proven that it can reduce energy requirements in the dimethyl ether synthesis process from methanol and increase net energy efficiency by up to 98.83%. The results of the case study indicate that the addition heat exchanger (E-100) able to reduce the heater load after the creation process and remove the cooler (E-101) that existed before creation, then the addition of the heater (E-104) serves to reduce the load of Qcond2 and Qreb2 on columns (T-102), also the position of the mixer for the methanol recycling flow is moved before the heater (E-100) is intended to remove the heaters (E-103). Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Partitioning among-animal variance of energy utilization in lactating Jersey cows

Animals vary in the way in which they utilize energy due to diet, genetics, and management. Energy consumed by the animal supports milk production, but considerable variation among-animals in energy utilization is thought to exist. The study objective was to estimate the among-animal variance in energy utilization in data collected from Jersey cows using indirect calorimetry. Individual animal-period data from 15 studies (n = 560) were used. The data set included 115 animals from 44 to 410 DIM producing 11.5 to 39.1 kg/d of milk. On average, the 63 treatments in the data set ranged 14.8 to 19.5% CP, 21.4 to 43.0% NDF, 16.2 to 33.3% starch, and 2.21 to 6.44% crude fat. Data were analyzed with the Glimmix procedure of SAS (9.4) with random effects of cow, treatment nested within period, square, and experiment. The percentage of among-animal, dietary treatment, and experimental variance was calculated as the variance associated with each fraction divided by the sum of variance from animal, dietary treatment, experiment, and residual which was considered the total variance. The percentage of among-animal variance was characterized as high or low when the value was greater than or less than the mean value of 29.2%. Among-animal variance explained approximately 29.3 - 42.5% of the total variance in DM intake (DMI), gross energy (GE), digestible energy (DE), metabolizable energy (ME), and net energy of lactation (NEL) in Mcal/d. When energetic components of feces, urine, and heat in Mcal/d were expressed per unit of DMI the among-animal variance decreased by 20.4, 4.82, and 9.55% units, respectively. However, among-animal variance explained 4.80, 8.78, and 5.02% units more of the total variation for methane energy, lactation energy, and tissue energy in Mcal/d when expressed per unit of DMI. Variance in energetic efficiencies of DE/GE, ME/GE, and ME/DE were explained to a lesser extent by among-animal variance (averaging 17.8 ± 1.95%). The among-animal contribution to total variance in milk energy was 28.8%. Milk energy was a large proportion of the energy efficiency calculation which included milk energy plus corrected tissue energy over net energy intake which likely contributed to the 22.2% of total among-animal variance in energy efficiency. Results indicate that among-animal variance explains a large proportion of the total variation in DMI. This contributes to the variance observed for energy fractions as well as energy components when expressed in Mcal/d. Variation in energetic loss associated with methane was primarily explained by differences among-animals and was increased when expressed per unit of DMI highlighting the role of inherent animal differences in these losses.

MAPPING THE LINKS BETWEEN RESOURCE EFFICIENCY AND THE INNOVATIVE CAPACITY OF NATIONAL ECONOMIES

The article examines studying the relationship between the level of innovation in different countries and the efficiency of their resource use, in order to better understand the potential impact of increased adoption of new technologies on the responsible use of resources in the future. Two country’s samples were created for the study: the first includes 36 world economies, with calculations of energy and labour resource use efficiency, taking into account the size of the economy and the level of innovation achieved; the second sample includes data on the material footprint of 121 countries, along with levels of innovation and economic development. The empirical confirmation of the hypothesis that there is a relationship between the level of economic innovation achieved and the efficiency of resource use is a key finding. Furthermore, the results of the correlation analysis indicate a direct and close relationship between a country’s economic innovativeness and its consumption volume of natural resources. This relationship can be described by a linear function. The analysis also confirms that as the population’s welfare and economic innovativeness grow, the state’s material footprint increases. The study is of theoretical and practical importance, encouraging the improvement of tools to ensure innovative development based on responsible production and consumption of resources. This approach aims to achieve better results at the same cost. Identifying the necessary factors related to innovative activity and efficient resource use by enterprises, as well as establishing functional dependencies between these variables, represent prospective areas for further research. In addition, a detailed examination of the experiences of Russian companies and their implications regional differentiation in terms of innovation and resource efficiency is a logical next step.

Measurement of steam dryness using one-dimensional acoustic waves in pipelines

Heavy oil, extra-heavy oil and bitumen exceed 6 trillion barrels, roughly three times the world total Conventional oil and gas reserves. Thermal-chemical flooding (TCF) is an effective alternative to enhance heavy oil recovery after steam injection. In the steam injection and extraction process of oil, the accurate measurement of water steam dryness can provide a strong guarantee for the efficient exploitation of oil fields. The traditional steam dryness measurement device is affected by the steam flow state, and the error generated will affect the enthalpy calculation of the injected steam, which affects the judgment of energy efficiency of oil well injection in the field. Firstly, this paper proposes a mathematical model for calculating water steam dryness using mixed sound velocity and operating temperature, which is based on the mathematical relationship between water steam dryness and gaseous volume fraction, combined with Wood's formula and the density and sound velocity calculation formula for each region in the IAPWS-IF97 model to derive the monotonic correspondence function of sound velocity and dryness. Secondly, the one-dimensional acoustic wave model of the pipeline is applied to establish a set of sound velocity equations for the frequency-domain data of the array sensors, and the traversal iteration method is used to solve the mixed sound velocity of water steam. Finally, the dryness of steam injection under the operating condition of 270°C∼290°C at the wellhead was measured in the experimental area H33 in Xinfanguan of Liaohe Oilfield, and compared with the standard dryness value, the relative error of the experiment was -3.33% and the repeatability was 1.24%, the accuracy met the requirements of energy efficiency calculation, which verified the feasibility of the sound velocity method to measure the dryness of water steam. Therefore, it is of great engineering guiding significance to utilize sound velocity method to realize the measurement of dryness in the thick oil steam injection process.

Energy, exergy and sustainability analyses of nanoparticles added to fuels to reduce carbon footprint

In this study, experimental and thermodynamic analyses were used to investigate the use of fuel blends created by adding cerium oxide (CeO2) and aluminium oxide (Al2O3) nanoparticles to diesel/heavy fuel oil (HFO) fuel blends in a compression ignition engine. In the study, a single-cylinder compression ignition engine was tested at four different engine loads at a constant engine speed of 3000 rpm. The experiments measured engine power, fuel consumption, exhaust gas temperature, engine casing temperature and exhaust pollutants. Thus, a study on energy, efficiency and sustainability was carried out by comparing fuel blends. All fuel blends were subjected to energy and exergy efficiency, lost exergy and sustainability index calculations. The addition of nanoparticles to the fuel increases the energy loss compared to the D80F20 (80% Diesel + 20% HFO) fuel blend. Comparing D80F20AL100 (80% Diesel + 20% HFO + 100 ppm Al2O3) and D80F20CE100 (80% Diesel + 20% HFO + 100 ppm CeO2) fuel blends, the exergy loss of D80F20 fuel is 10.76% and 14.23% higher when the engine power is 4000 W, respectively. The energy efficiency of D80F20 fuel increases as more nanoparticles are added and reaches 12.60% and 12.80% for D80F20CE25 (80% Diesel + 20%HFO + 25 ppm CeO2) and D80F20CE100 fuels under 3000 W engine load, respectively. The inclusion of nanoparticles in diesel/HFO fuel blends gives results in line with the sustainability index.

Influence of Balcony Thermal Bridges on Energy Efficiency of Dwellings in a Warm Semi-Arid Dry Mediterranean Climate

Thermal bridges significantly influence the energy performance of buildings. However, their impact varies depending on the type of thermal bridge, climate conditions, construction methodologies, and geometric characteristics of the building. On the Spanish Mediterranean coast, buildings with large balconies are predominant. Nevertheless, the Spanish energy efficiency regulations do not adequately specify the thermal bridges at the junctions of balconies with facades, leading to a lack of consideration for their influence in the majority of architectural projects. The objective of this study is to qualitatively and quantitatively assess the impact of such thermal bridges on the energy efficiency of buildings in a dry Mediterranean climate (BShs) within a warm semi-arid climate (BSh). As a case study, the influence of this thermal bridge is analyzed in two residential buildings located on the Mediterranean coast of southeastern Spain. The study also examines the modification of various construction parameters of this thermal bridge and determines the optimal design parameters to reduce its thermal transmittance. The results demonstrate that the energy needs caused by thermal bridges account for approximately 40% of the total annual energy needs of the studied residential buildings. Balcony thermal bridges account for 25% to 40% of the energy needs caused by all thermal bridges. The lack of differentiation in Spanish standards between balcony–facade and facade–slab edge junctions causes an imprecision in calculations equivalent to 12% of the total annual energy needs of dwellings. The novelty of this research lies in highlighting that current regulations and calculation programs need improvement to better characterize balcony thermal bridges and enhance the accuracy of building energy efficiency calculations.

Ensuring Sustainability of Residential Buildings by using Local Materials in the Conditions of the Republic of Moldova

The study is an overview of the current situation in the Republic of Moldova regarding the sustainability of residential buildings. Advances in the building industry indicate a shift towards energy efficiency with minimal consumption. The authors aim to find a sustainable solution for implementation in the Republic of Moldova. To achieve this, they perform energy efficiency calculations for the envelope of a residential building that utilizes locally available limestone blocks, sourced from 44 quarries across the territory. Technical abbreviations will be defined upon their first use. For thermal insulation, the authors suggest using two layers of masonry enclosing 6 cm thick polyurethane foam. The purpose of this study is to highlight the importance of sustainability in the construction of new residential buildings in the Republic of Moldova. This is particularly relevant in the absence of a comprehensive regulatory framework on energy efficiency for residential buildings.

Solar-assisted poultry production in small-scale farms: a case study in the Bekaa semi-arid region, Lebanon

BackgroundIn Lebanon, poultry production is one of the major components of the agricultural sector; however, it suffers from increasing energy costs necessary to cover poultry heating requirements. This affects the profits of brooding farms, namely, small-scale farms in rural areas. Few studies have addressed the use of renewable energy in the poultry industry in Lebanon, with most having focused on modelling ventilation and air quality requirements in poultry houses. Therefore, there is a need to investigate the efficiency of renewable energy sources in providing heating requirements for poultry production. Accordingly, this study evaluates the performance of a solar-assisted, localized heating system in providing heat requirements for chicks in a renovated green poultry house in the Bekaa semi-arid rural region in Lebanon. For this aim, two brooding cycles were conducted during the warm and cold seasons in a greenhouse and were later replicated in a conventional poultry house.ResultsThe energy inputs in the green and conventional houses, respectively, were 33,995.39 and 40,656.97 MJ (1000 birds)−1 in the warm season, and 37,058.25 and 45,770.05 MJ (1000 birds)−1 in the cold season. Calculated energy efficiency values for the green and conventional poultry houses were, respectively, 0.58 and 0.50 in the warm season, and 0.46 and 0.41 in the cold season. The net return was negative for both systems and the benefit-to-cost ratio from broiler production was calculated to be 0.49 and 0.50 in the green and conventional houses, respectively. Life cycle cost analysis showed that adopting the green heating system in the studied farm would entail an 18.89% increase in cost over a period of 20 years as compared to the conventional system.ConclusionIt was concluded that poultry production is not profitable in small-scale farms in the studied area in Lebanon. The use of renewable energy might be more suited for large-scale broiler operations to achieve their purpose in reducing overall production costs. Optimization of the green system to fully satisfy the poultry energy requirements would render it more economically competitive.

Experimental study on a concentrating solar photovoltaic/thermal system using different fluid spectral beam filters

Spectral splitting photovoltaic/thermal technology is the leading field in the area of extremely efficient utilization of solar energy. Due to its complexity, experimental research on spectral splitting photovoltaic/thermal devices is relatively limited, mainly focusing on the laboratory scale energy efficiency test or calculation process verification. These studies do not provide intuitionistic guidance for the actual operation of engineering systems. In this paper, a fluid filter-based compound parabolic concentrator solar photovoltaic/thermal system with engineering application dimensions is designed and experimentally studied under actual outdoor environments. Different fluid filters are prepared and used to regulate the spectral splitting characteristics of the proposed system, including the deionized water, silver/water nanofluids and silver-cobalt sulfate/water nanofluids. When the environmental parameters are relatively stable, the method of adjusting the composition of the fluid filter is used to obtain the dynamic operating characteristics of the system. The results show that silver nanoparticles and cobalt sulfate can improve the spectral absorptivity of the deionized water. Compared with the deionized water, when the silver/water nanofluids is used as the fluid filter, the thermal efficiency of the system increases, the electric efficiency and overall exergy efficiency of the system both decrease, and the three efficiencies are 56.0%, 8.5% and 19.6%, while for the silver-cobalt sulfate/water nanofluids, the efficiencies are 58.0% 8.0% and 20.0%. Moreover, the results reveal that for the photovoltaic/thermal system with a low solar concentration ratio, by enhancing the absorptivity of the fluid filter, the fill factor of the photovoltaic module can increase, but the output electric power will decrease. When the silver-cobalt sulfate/water nanofluids is used, the fill factor and maximum output power of the proposed system are 0.633 and 69.2 W. For a unit consisting of four sets of the proposed photovoltaic/thermal systems, the emission reductions of CO2, NOx, SO2 and dust for the whole lifetime are approximately 7794.19 kg, 181.48 kg, 191.95 kg and 111.68 kg, respectively.

Benincasa hispidas-inspired pore-gradient aerogel with integrated water and thermal management for highly efficient solar vapor generation and water purification

Engineering the pore structure of evaporator to effectively integrate water and thermal management is critical for efficient solar-driven interfacial vapor generation. Here, inspired by the unique structure of Benincasa hispidas, a bioinspired pore-gradient aerogel was fabricated for the first time. Experiments and numerical simulations reveal that the unique anisotropic porous structure of aerogel, which consists of small-pores at top region and large-pores at bottom region, enabling it to maximize the heat gains from the sunlight and localize the generated heat while provide adequate water supply concurrently. Under solar illumination (1 kW m−2), the fabricated aerogel can achieve a high evaporation rate of 2.49 kg m−2h−1, and the calculated energy efficiency is approximately 96.3 %, which is comparable to most of state-of-the-art evaporators. Additionally, with this aerogel employed, effective purification toward various undrinkable water can be achieved. This work derives from nature, providing us a design blueprint to integrate water and thermal management in a bulky material, and it is expected to advance one step further toward the design and practical application of high-performance solar evaporators.

High Purity Hydrogen and Carbon Dioxide Separation with Electrochemical Pump Operation of HT-PBI Fuel Cell at 120°C

A commercially available, polybenzimidazole (PBI) membrane based electrochemical hydrogen pump (EHP) platform was thoroughly evaluated to generate a benchmark set of performance. A primary gas mixture of CO2 and H2 with a ratio of 4:1 was selected to demonstrate the performance of EHPs while addressing concerns of CO2 poisoning effect. There is no indication of significant CO poisoning as a result of reverse water gas shift reaction (RWGS), and nearly Faradaic current efficiencies were successfully achieved. 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 tightly controlled relative humidity of feed gas. A new perspective on EHP energy efficiency calculation methodology is also provided by inclusion of the cell heating requirement into the calculation. In this manner, an overall improvement to energy efficiency nearing 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%.

Investigating the energy efficiency determinants in EU countries by using multi-criteria decision analysis and the Tobit regression model

ABSTRACT This study investigates the effects of several contextual variables, including renewable energy intensity, capital stock per labor, natural resource rent, the share of imported energy in total energy consumption, the ratio of carbon emissions to GDP, population, and energy production on energy efficiency in EU countries. While Tobit regression is used to examine the effects of contextual variables on energy efficiency, Data Envelopment Analysis (DEA), Slack-Based Data Envelopment Analysis (SBM-DEA), and Technique for Order of Preference by Similarity to the Ideal Solution (TOPSIS) are used to calculate energy efficiency values of countries. Four different Tobit regression models are estimated as a function of the censored value for the energy efficiency series. The results show that renewable energy intensity, the ratio of carbon emissions to GDP, and population size have negative effects on energy efficiency. In contrast, regardless of the efficiency level, the share of imported energy in total energy consumption, total energy production, capital stock per labor, and technological progress have positive effects on energy efficiency.

Energy Efficiency Model Construction of Building Carbon Neutrality Design

We aim to create a feasible quantitative method to calculate the energy efficiency of building designs that are carbon-neutral and to develop a workable way of calculating energy efficiency in buildings that achieve carbon neutrality and the system for such a building’s design energy efficiency function. This paper first clarifies the idea of the design energy efficiency function for a carbon-neutral building over its whole life cycle. Subsequently, through the efficient analysis of carbon-neutral design dimension measures, this paper summarizes and integrates the mature theories of various disciplines, puts forward the energy efficiency function model of carbon-neutral design background, propulsion, and coverage, and implements the energy efficiency function model of carbon-neutral design in the whole life cycle of buildings. The index value of a building’s carbon emission factor is established based on the carbon accounting factor published by the Intergovernmental Panel on Climate Change, and a carbon neutrality energy efficiency model for buildings over the duration of their whole life cycle is constructed. The results were as follows. 1. Technology energy efficiency is far better than scale energy efficiency and comprehensive energy efficiency. 2. The better the energy efficiency value inside the building stage, the less consumption and the higher the production. 3. Construction is when technical energy is used the least. This paper refers to a systematic design method that makes the level of building carbon neutrality design technologically advanced with the aid of all types of big data related to the building life cycle and various innovative design theories in order to fully represent the fundamental level, development potential, and the effectiveness of choosing the strategy of building carbon neutrality.

Design of IOT-Based Framework for Evaluation of Energy Efficiency in Power Transformers

Two prototypes with energy efficiency calculations have been developed to enable real-time efficiency assessment and data collection. The results of the experiment demonstrate that the use of microprocessor technology and the Internet of Things can significantly improve the efficiency and accuracy of energy audits in power transformers. The prototypes developed in this study provide real-time efficiency assessment and data collection, enabling more effective energy management and cost savings for industrial users. During the experiment, it was found that resonance can cause the same losses as a poor power factor of the system, highlighting the importance of addressing energy quality issues in addition to energy efficiency. These findings have important implications for energy efficiency policies and practices in the context of climate change mitigation and rising energy prices.

Reserves of available soil moisture, productivity and mass of root residues of winter wheat and post-harvest white mustard depending on cultivation, precursors and fertilizer

Three-year (2020–2022) research at the experimental field of Bila Tserkva National Agrarian University, make it possible to calculate the economic and energy efficiency and to recommend a differentiated system of the main tillage on typical deep, low-humus medium-loamy chernozems of the Right Bank Forest-Steppe of Ukraine in a five-field specialized (cereal) crop rotation, which involves deep plowing only for row crops, and for winter wheat after both predecessors (peas and buckwheat) and post-harvest mustard for green manure cultivation with heavy disc harrows, respectively, to a depth of 8–10 and 10–12 cm with the introduction of N140P60K100 under the bread plant and N120P60K90 – after peas, and under cabbage – N80P60K80 after both predecessors. For the placement of winter wheat after legume and cereal crops and recommended agricultural measures, the cost of one ton of grain was 3.82 and 4.06 thousand hryvnias respectively, conditional net profit was 18.11 and 16.06 thousand hryvnias/ha, profitability 44.4 and 37.1 %, energy efficiency ratio 2.4 and 1.9. Reserves of available soil moisture under winter wheat are higher in the link with peas than buckwheat. The highest reserves of it in the upper, arable and meter layers in the seedling phase of the culture after both predecessors under differentiated cultivation in crop rotation. In the phase of entering the tube, this indicator is the lowest in the arable layer under differentiated, and in the meter layer - under disk cultivation in crop rotation. On the date of sowing white mustard in the row with peas, the reserves of available soil moisture in the upper layer differed insignificantly according to tillage options, and in arable land they are the highest under shelf-disc tillage. In the meter layer, this indicator did not undergo significant deviations from the control, although it increased compared to it by 1.2–2.5 mm. For the predecessor of buckwheat, the content of soil moisture in the investigated layers (0–10, 0–30 and 0–100 cm) on the date of sowing white mustard increased significantly under differentiated and decreased significantly under disk tillage. In the upper layer of the soil, this indicator is slightly higher in the link with peas (by 0.5 mm), in the arable one with buckwheat (by 2.6 mm), and in the meter layer – it is almost the same for both predecessors. The yield of winter wheat is 0.59 t/ha higher in the link with peas than with buckwheat. After both predecessors, it is the largest under differentiated cultivation of fertilized and unfertilized plots. With chisel-disk and disk processing, this indicator is significantly reduced. Only on unfertilized plots under shelf-disk and disk tillage, the yield of green mass of white mustard is higher in the link with peas than with buckwheat, in the remaining variants of the experiment, the preference is for the grain predecessor. This indicator in the link with peas decreased, for all tillage options, compared to the control, but significantly only for disc tillage. In the link with buckwheat, its significant decrease is observed under disc cultivation and a significant increase under differentiated cultivation of fertilized areas. The dry mass of root residues of winter wheat is significantly lower for chisel-disc and disc than for shelf-disc treatments in both predecessors. Under differentiated processing, this indicator increased, compared to the control, but insignificantly. The mass of the dry root of white mustard in the link with leguminous crop is less for all tillage options, compared to the control, but it is significantly (by 0.19–0.25 t/ha) less for discing the soil. With an increase in fertilizer application rates, the dry weight of the root residues of the studied crops grows more slowly than the yield. At the same time, a slower growth of both above-ground and underground mass of both agrophytocenoses was established for placing them after the leguminous than for the cereal predecessor. Calculations of economic and energy efficiency give reason to recommend a differentiated system of the main soil cultivation on typical deep, low-humus, medium-loam chernozems of the Right Bank Forest Steppe of Ukraine in a five-field specialized (cereal) crop rotation, which involves deep plowing only for row crops, and for winter wheat after both predecessors (peas and buckwheat) and post-harvest mustard for green manure tillage with heavy disc harrows, respectively, to a depth of 8–10 and 10–12 cm with application of N140P60K100 under the bread plant after 1 buckwheat and N120P60K90 – after peas, and under cabbage – N80P60K80 after both predecessors. For placing winter wheat after leguminous and cereal crops and recommended agromeasures, the cost price of one ton of grain was UAH 3.82 and 4.06 thousand respectively, conditional net profit was UAH 18.11 and 16.06 thousand/ha, profitability 44.4 and 37.1 %, energy efficiency ratio 2.4 and 1.9. Key words: soil, cultivation, productivity, fertilizers, predecessors, cultures, root residues, crop rotation.

Combined numerical approach for the evaluation of the energy efficiency and economic investment of building external insulation technologies

The objective of this paper is to examine the energy efficiency and economic feasibility of different coating technologies used to improve the thermal insulation of external walls in buildings. The comparison is made between traditional coat insulation and ventilated façade, evaluating their impact on energy consumption to maintain a constant indoor temperature throughout the year by means of a combined numerical approach. . Furthermore, the paper investigates the effect of opening and closing the air gap in ventilated façades on thermal insulation during the winter and summer seasons. Energy efficiency calculations are employed to estimate the economic investment required for implementing the different insulation solutions.The paper proposes an innovative combined approach to determine the performance of the building insulation technologies. Firstly, a computational fluid dynamics (CFD) simulation is carried out on the full three-dimensional geometry of the building during two reference days representing extreme temperature and sun radiation conditions during the summer and winter. This modeling includes the effects of solar radiative heat transfer during the day: for a chosen date, time, and geographical location, the model computes sun altitude and azimuthal angles, along with the corresponding direct and diffuse solar fluxes. In addition, the model uses a multiband thermal radiation approach to capture the different nature of radiative heat exchange according to the light wavelengths. The total heat transfer coefficient of the building walls in each scenario is calculated through the computational fluid dynamic analysis and implemented in an in-house developed library based on the open source Open-Modelica platform to simulate the energy requirement of the building throughout the year. This combined numerical approach provides a comprehensive performance analysis of the studied technologies in terms of electric energy and fuel consumption required for maintaining a constant indoor temperature and internal ambient comfort.The results of the simulations demonstrate that by adopting the two proposed solutions, there was a potential to save approximately 37% of the fuel required for the heating system and more than 51% of electric energy required for the air conditioning systems. Finally, the payback period for each scenario is calculated, and it was found that coat insulation offers the best balance between thermal performance improvement and economic effort, with a payback time close to 20 years.

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.