Lower Total Energy Consumption Research Articles

Daylight and energy performance of side lighting systems in an office room in a subtropical climate

In office buildings, daylight is an important natural resource, as it is profusely available during occupied hours. However, its use can increase energy consumption for air conditioning. Therefore, combining this resource with side lighting systems and promoting its integration with electric lighting is essential to obtain an energy balance. This paper aims to analyze daylight performance and the energy consumption for lighting and air conditioning considering four types of glazing, four orientations, from window-to-wall ratios varying between 40% to 100% for bare and shaded window models in an office room located in a subtropical city in southern Brazil. The methodology was based on Useful Daylight Illuminance levels of 500 to 2,500 lx, Daylight Autonomy levels of 500 lx, and total energy consumption through simulation in DesignBuilder software. The results showed that L13 glazing is not recommended for bare and shaded windows, regardless of window orientation. M76 presented the best performance for energy consumption for West shaded windows. For the West, shading is necessary irrespective of the glazing type (except L13, whose best performance is for bare windows) from WWR 50%. M76 and M52 had the lowest total energy consumption. The findings of this study add to an understanding of the energy savings and lighting performance of different types of glazing, combined with window apertures, and solar orientations for a subtropical climate. Furthermore, the study shows that the choice of glazing depends not only on the presence of shading but also on the orientation and WWR, without a linear behavior.

Food Consumption and Weight Recurrence in Patients Undergoing Bariatric Surgery with a Minimum of 2 Years Post-surgery.

Eating habits are one of the factors that directly affect weight recurrence after bariatric surgery, and therefore, this study assessed the association between food consumption and weight recurrence in patients who underwent bariatric surgery a minimum of 2 years. A cross-sectional observational study was conducted with patients who underwent bariatric surgery a minimum of 2 years through SUS, in the city of Palmas, Tocantins. Food consumption was assessed through two 24-h dietary recalls (R24). The foods were classified into groups by degree of processing following the NOVA classification system. Also, macronutrients and fiber contents were quantified. Anthropometric variables were evaluated and weight recurrence (WR) was defined as 15%. Ninety-three (93) patients participated in the study, being 83.9% female, with mean age of 43.5 ± 9.13 years, mean post-surgery time of 4 years, and 58% present WR. A lower total energy consumption was found in patients without WR compared to those with WR (p = 0.05). Among the WR group, calories from processed foods (p = 0.00) and culinary ingredients (p = 0.05) were higher. However, carbohydrate consumption (percentage) was lower in the WR group (p = 0.04). A positive correlation was found between total energy (p = 0.03), processed foods (p = 0.03) and weight recurrence (p = 0.03). Weight recurrence is associated with total daily energy intake, carbohydrates and food groups classified according to NOVA.

Effects of microwave dryers on the properties of Jerusalem artichoke: physico-chemical, thermo-physical, energy consumption

Effects of pretreatments and drying methods on physico-chemical, thermo-physical, energy values were investigated. The longest drying duration was seen in control samples dried in hybrid microwave dryer at 350 W + 50 °C and the shortest in citric acid-treated samples dried in temperature-controlled microwave dryer. Citric acid-treated samples dried in temperature-controlled microwave dryer at 70 °C had the closest color values to fresh ones. Effective diffusion values of dried Jerusalem artichoke samples varied between 4.66 x 10−8 − 1.33 x 10−7 m2 s−1 and activation energy values varied between 14.53 − 41.74 kJ mol−1. Drying date was estimated with the Midilli-Küçük model. The highest specific heat, thermal conductivity and thermal diffusivity values were observed in control samples dried in temperature-controlled microwave oven at 60 °C and the highest density values were seen in citric acid-treated samples dried in hybrid microwave oven at 70 °C. The highest SMER value was observed in control samples dried in temperature-controlled microwave dryer at 60 °C. The lowest SEC value was seen in control samples dried in temperature-controlled microwave dryer at 60 °C. The lowest total energy consumption was encountered in citric acid-treated samples dried in temperature-controlled microwave dryer at 70 °C.

A modified beluga whale optimization for optimizing energy-efficient no-idle permutation flow shop scheduling problem

Attention to energy-efficient permutation flow shop scheduling problems is increasing in the context of globalization and environmental awareness. However, the energy-efficient no-idle permutation flow shop scheduling problem (NIPFSP) has rarely been studied. This study proposes a procedure using Beluga Whale Optimization (BWO) to solve the energy-efficient NIPFSP issue to reduce total energy consumption (TEC). The offered procedure is tested using four job and machine variations and compared with the PSO algorithm. An independent sample t-test was performed to test the optimization results of the BWO and PSO in 4 cases. The results indicate that the offered procedure produces lower total energy consumption than the PSO algorithm. In addition, the algorithm also provides more competitive results when solving the energy-efficient NIPFSP problem with a larger number of jobs. The implications of this academic research show that the proposed procedure can be applied to solve the problem of energy-efficient NIPFSP, which is indicated by low energy consumption.

A chemically enhanced backwash model for predicting the instantaneous transmembrane pressure of flat sheet membranes in constant flow rate mode

In this study, a new model was proposed based on the cascade process of the chemical reaction and the physical removal mechanism to predict the instantaneous transmembrane pressure (p(t)) of yeast-fouled 0.1 μm polyacrylonitrile (PAN) membranes in the chemically enhanced backwash (CEB) process. The results indicated that the model predictions were in good agreement with the experimental data. Additionally, the transition point of the CEB mechanism, which changed from a combined cleaning (pore cleaning and cake cleaning) mechanism to an individual cake cleaning mechanism, appeared earlier at higher NaOCl concentrations or CEB fluxes. The corresponding available membrane area ratio also tended to stabilise earlier. In addition, the model predictions for different suspensions or solutions, membranes (0.1 μm polyethersulfone (PES) and polyvinylidene fluoride (PVDF) membranes), and chemical reagents were also in good agreement with the experimental data. Moreover, the integral of p(t) was used to correct Masse's energy consumption equation. The results show that the calculation method for the corrected equation is theoretically more accurate. Lower total energy consumption was obtained at a higher NaOCl concentration or lower CEB flux.

Distributed total-amount optimal coordinated control of multi-motors with input and output saturation

Specific to the double saturation constraints of input and output in multimotor network systems, an anti-windup control framework with distributed total-amount optimal coordination is constructed, and a new saturated super-twisting sliding mode control strategy is designed in this paper. First, a mathematical model of direct torque and flux control of a multipermanent magnet synchronous motor is established. Next, the consistency of the total amount and output saturation are taken as the constraint conditions. Considering the lowest total energy consumption, the optimal multi-axis total-amount coordinated allocation algorithm is designed on the basis of the Karush-Kuhn-Tucker (KKT) condition. Then, the input saturation is introduced into the dynamic integral part of the super-twisting algorithm. A new saturated super-twisting sliding mode tracking control algorithm is designed, and the barrier Lyapunov function is used to prove the input constraint. Finally, the Matlab/Simulink simulation and RT-LAB semi-physical experiments verify that the anti-windup control strategy of distributed total-amount optimal coordination can effectively solve the double saturation constraints of input and output.

Development and Simulation of Natural Gas Refining Mechanism Based on Exergy Study

Abstract: This study will examine a domestic gas field in Bayelsa, Nigeria, to improve the natural gas purification process. This study's main goals are to reduce energy use and improve purification levels. A complete technical and economic assessment was carried out utilizing Aspen Plus TM software. The absorption parameters reflux ratio and stage number were estimated using single-factor sensitivity analysis. The energy system's energy-saving technique was used to examine the heat transfer mechanism and recommend a change. The optimization results show that the suggested system has better purifying performance, lower total energy consumption, and 9 percent improved energy efficiency.

A digital twin-based multi-objective optimization method for technical schemes in process industry

ABSTRACT To solve problems of technical objective conflicts, untimely feedback, and inaccurate decision making, a multi-objective optimization method was developed for technical schemes in process industry based on digital twin. According to actual requirements, a multi-objective optimization problem was established with key technical parameters and constraints determined. A digital twin model was built to achieve a real-time interaction between physical and virtual production systems and assist in optimization. For optimization efficiency and adaptability to different working conditions, a dynamic acquisition function-based Bayesian method was adopted to fit original complicated functions and obtain Pareto optimal solutions. A rapid decision-making was carried out by comprehensively utilizing dynamic parameter set correlation evaluation, entropy weight method, and technique for order preference by similarity to ideal solution. A typical case study of optical fiber preform drawing process was presented to prove the method effectiveness. Results demonstrated that the proposed method was valuable for actual application with better product quality (an improvement by 0.71% for preform rod diameter precision control), higher utilization rate of raw materials (an increase by 3.64%), and lower total energy consumption (a reduction by 4.37%).

Effect of the Surface Treatment Process of Filter Bags on the Performance of Hybrid Electrostatic Precipitators and Bag Filters

Hybrid electrostatic precipitators consisting of electrostatic precipitation (ESP) and a bag filter are potential devices for ultralow emissions. The ESP captures and charges the particles; subsequently, the charged particles that escape enter the bag filter. The charged particles can cause the electric field of the filter bag to develop, thereby enhancing the filtration efficiency due to the force of the electric field. Experiments based on the coupling-reinforced electrostatic–fabric integrated precipitator system were conducted to investigate the outlet total dust concentration, dust removal efficiency, pressure drop, energy consumption of bag filter, and hybrid electrostatic precipitators with various filter bags. The measured results demonstrate that the removal performance of filter bags with smaller fiber diameters was superior. However, the pressure drop and energy consumption were high due to the increased filtration resistance. Compared to bag filters, hybrid electrostatic precipitators had lower total and grade dust mass concentrations at the outlet, higher total and grade dust removal efficiencies, a minor average pressure drop variation per minute, and lower total energy consumption. Consequently, the quality factor was utilized to comprehensively evaluate the overall performance of dust collectors. The hybrid electrostatic precipitators had a significant greater quality factor; their overall performance was superior to that of bag filters. Overall, a smaller filter bag’s fiber diameter resulted in more effective dust removal capabilities. Hybrid electrostatic precipitators with various filter bags were significantly better than bag filters in terms of dust removal performance, cycle life, and energy consumption.

Multi-objective analysis of evacuated tube solar-electric hybrid drying setup for drying lotus bee pollen

This work aims to develop an evacuated tube solar-electric hybrid drying setup and enhance its performance using evacuated collector and photovoltaic systems. The setup performance was evaluated by dehydration of lotus bee pollen using two different strategies inducing solar heating drying and mixed heating drying at three different temperatures (40, 50, and 60 °C). The system was also compared with open sun drying. Compared with open sun drying, about 45%, 23%, 30%, and 41% reduction in the process time was induced by solar heating drying and mixed heating drying (40, 50, and 60 °C), respectively. For both solar heating and mixed heating drying, the mechanical energy, thermal energy generated by electric heating tubes, and radiation thermal energy accounted for were in the range of 12.2–38.5%, 0.0–15.3%, and 60.5–87.8%, respectively. From the perspective of drying efficiency and energy consumption, the developed evacuated tube solar-electric hybrid drying setup was more beneficial under mixed heating drying at 40 and 50 °C. The dryer efficiencies under the cases of mixed heating drying at 40, 50 °C were 48% and 34% higher than that of solar heating drying, while mixed heating drying had lower total energy consumption, specific energy consumption and specific electric energy consumption. The developed equipment can effectively reduce greenhouse gas emissions and has a short payback period of 1.24 years. Based on the findings of this research, it could be concluded that, resulting in decreased drying time, GHG emissions and enhanced energy efficiency, the developed equipment is a promising drying technology.

Augmentation of natural convection heat transfer in enclosures via ultrasound: Effects of power, frequency and temperature

• Ultrasonication improves convective heat transfer in enclosures by as much as 77%. • Effect of ultrasonic power heightens at higher frequencies. • Acoustic streaming observed to contribute the most to the observed enhancement. • Per unit ultrasonic power, the observed enhancement is proportional to frequency. • Only at higher frequencies, integration of ultrasound results in energy-saving. The integration of ultrasound to enhance the natural convection heat transfer in an enclosure was experimentally investigated. The effects of ultrasonic power, ultrasonic frequency and surface temperature on convective heat transfer coefficient were analyzed to optimize the ultrasonic input. A novel dimensionless number is defined that indicates the ultrasound-induced convective heat transfer enhancement per added unit of delivered ultrasonic power. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, the total energy to the system to increase the temperature to a certain degree in non-ultrasonic and ultrasound-assisted experiments was compared. With respect to ultrasonic power, application of ultrasound at any power level enhances the convective heat transfer coefficient by as much as 77% while the effect of power heightens with an increase in frequency. Amongst the three examined frequencies, integration of ultrasound was observed to enhance heat transfer more at higher frequencies. The surface temperature appears to have a negative effect on the observed ultrasound-enhanced heat transfer where higher temperatures abate the enhancement. Per unit ultrasonic power added to the system, higher frequencies show greater improvement in convective heat transfer. Comparing the trends in variation of the augmented heat transfer, the kinematic momentum resulting from acoustic streaming and the acoustic cavitation critical bubble radius with the ultrasonic frequency revealed that at lower frequencies acoustic cavitation is the augmenting mechanism and at higher frequencies acoustic streaming induces the enhancement with acoustic streaming having a higher impact in augmenting natural convection heat transfer. In terms of energy savings, a novel analysis focusing on the energy intensity of utilizing ultrasound unveiled that only at higher frequencies does integration of ultrasound result in lower total energy consumption.

Effects of Tool-Workpiece Friction Condition on Energy Consumption during Piercing Phase of Seamless Tube Production

During the hot piercing phase of seamless tube production, friction and contact conditions between tools and workpiece significantly influence final product quality and energy consumption. The friction effects on the production of high alloyed steels like Super Cr13 steel are critical. This study analyses the effect of different friction conditions at the workpiece-tool interface in the piercing of Super Cr13 steel bars to minimize total energy consumption in such a manufacturing process. For this purpose, a three-dimensional finite element method (FEM) is employed to simulate and analyze the piercing process. The variety of tools (plunge, rollers, and Diescher disks) and contact conditions lead to differences in the applied stress at different workpiece areas. Consequently, various friction models and friction coefficients were selected for different interfaces. The relation between strain rate, temperature, and geometry of pierced tube are discussed, and the selected friction relation with total power and energy consumption is presented. Experimental tests have been used for FEM validation and result analysis, and finally, the most effective conditions with lower total energy consumption are presented.

Latency-aware computation offloading and DQN-based resource allocation approaches in SDN-enabled MEC

The proposed mobile edge computing can transfer the computing tasks in mobile applications to the nearby edge devices, effectively reducing the processing pressure of local servers and avoiding delays in backhaul and core networks, thus better solving the problem that cloud computing cannot effectively handle resource allocation. However, the complexity of the wireless environment during the communication process leads to the fact that the computing tasks are easily caused by the increase in the number of traffic and packet loss when they are uploaded to the MEC side through the wireless link, which cannot guarantee a lower total system energy consumption and shorter total delay. To address the problem that mobile devices cannot handle many computationally intensive tasks in a timely manner, this paper proposes a task offloading optimization scheme for SDN-enabled MEC environments. Modeling the computation offloading problem based on Lyapunov optimization, and then analyzes the offloading delay with respect to the offloading gain. In order to guarantee application requirements, minimize energy consumption and latency, and better satisfy user QoS requests, this paper proposes a resource allocation strategy based on deep reinforcement learning. The strategy designs a DQN-based resource allocation algorithm to deploy a joint optimal offloading decision and resource allocation scheme in a mobile edge computing environment under the limited computational resources and the latency constraints of the computational tasks. Based on the experimental results, it is shown that the proposed task offloading strategy can reduce the overall latency; the proposed resource allocation strategy can reduce the total energy consumption and total latency of the system and improve the successful execution rate of tasks.

Hydrogen production from biogas: Process optimization using ASPEN Plus®

This work is part of the VABHYOGAZ (valorization of biogas into hydrogen) program, which targeted the industrial deployment of hydrogen production from biogas in France. To-date, different processes of methane reforming, such as steam reforming of methane (SRM), dry reforming of methane (DRM) and tri-reforming of methane (TRM), have been studied in the literature, but only SRM is applied at industrial scale. Since SRM is an energy-intensive process, a critical analysis of these routes for hydrogen production from biogas is indispensable for process optimization. This has been addressed in this work, by using ASPEN Plus® simulation. Different global processes of hydrogen production from biogas, via DRM, SRM, or TRM, with or without tail gas recycling, have been studied. Among them, hydrogen production using TRM technique (H2-TRM0.3C process) with a partial recycling of tail gas (30%) was found to be the best option, leading to the highest hydrogen production rate and the best energy yield. H2-TRM0.3C process was also found to be more efficient than the actual industrial process (H2-REF), which is based on SRM technique. Under the same conditions, H2-TRM0.3C process led to a higher H2 production (8.7% more), a lower total energy consumption (18.6% less), and a lower waste heat generation (15.4% less), in comparison with the actual industrial process (H2-REF).

ENERDGE: Distributed Energy-Aware Resource Allocation at the Edge.

Mobile applications are progressively becoming more sophisticated and complex, increasing their computational requirements. Traditional offloading approaches that use exclusively the Cloud infrastructure are now deemed unsuitable due to the inherent associated delay. Edge Computing can address most of the Cloud limitations at the cost of limited available resources. This bottleneck necessitates an efficient allocation of offloaded tasks from the mobile devices to the Edge. In this paper, we consider a task offloading setting with applications of different characteristics and requirements, and propose an optimal resource allocation framework leveraging the amalgamation of the edge resources. To balance the trade-off between retaining low total energy consumption, respecting end-to-end delay requirements and load balancing at the Edge, we additionally introduce a Markov Random Field based mechanism for the distribution of the excess workload. The proposed approach investigates a realistic scenario, including different categories of mobile applications, edge devices with different computational capabilities, and dynamic wireless conditions modeled by the dynamic behavior and mobility of the users. The framework is complemented with a prediction mechanism that facilitates the orchestration of the physical resources. The efficiency of the proposed scheme is evaluated via modeling and simulation and is shown to outperform a well-known task offloading solution, as well as a more recent one.

A novel solution for school renovations: Combining diffuse ceiling ventilation with double skin facade

With the aim to increase today's low retrofitting rate and thus decrease the currently rising energy consumption of the building sector, this work proposes a novel renovation concept for schools. Therefore, two components, double skin facade (DSF) and diffuse ceiling ventilation (DCV), are combined with an exhaust ventilation system, providing an alternative to a traditional renovation where windows are replaced, the external wall is insulated and a balanced ventilation system is installed. Further, based on a Danish case study classroom, different configurations of the novel system, with varying glazing properties and DSF cavity thicknesses are compared against a range of traditional renovations through building performance simulation using IDA-ICE. The results indicate that the new system can achieve up to 11% lower total primary energy consumption as the best traditional renovation while achieving an equal indoor environmental quality and therefore offering designers and engineers a competitive alternative for school renovation projects. Additionally, employing a sensitivity analysis, it could be demonstrated for the primary energy consumption and the global thermal comfort that the glazing (number of panes and physical properties) has a superior influence on the novel system compared to the cavity thickness.

A novel heuristic method for the energy-efficient flexible job-shop scheduling problem with sequence-dependent set-up and transportation time

With the increasing attention on environmental issues, green scheduling in manufacturing industries has become a hot research topic. As a typical scheduling problem, the flexible job-shop scheduling problem (FJSP) has received increasing attention, but research on the FJSP considering set-up and transportation times simultaneously is still rare. To address the energy-efficient FJSP with sequence-dependent set-up and transportation times to minimize makespan and total energy consumption, a multi-objective mixed-integer linear programming model of the problem is formulated and an effective novel heuristic method (NHM) is proposed. To enhance the convergence and distribution of the NHM, three strategies—population initialization, greedy iterative decoding and local intensification—are designed. The performance of the NHM is demonstrated by comparison with three algorithms through 48 instances. The results show that the NHM can obtain a scheduling scheme with lower makespan and total energy consumption than those of the comparison algorithms.

ЭФФЕКТ ВОЗДЕЙСТВИЯ ПЕРЕМЕННОЙ ТЕМПЕРАТУРЫ ИНКУБАЦИИ НА РОСТ И МЕТАБОЛИЗМ КУРИНЫХ ЭМБРИОНОВ ЯИЧНЫХ КРОССОВ И РАЗВИТИЕ ИХ ВИСЦЕРАЛЬНЫХ ОРГАНОВ

The article discusses issues related to the impact of variable incubation temperature (37.8°C – from the 1st to the 14th day; 39.5°C, two hours daily, in the 15th-17th days; 37.5°C – 18th day; 37.0°C – 19th-21st day; relative humidity is 57.0%) on the growth and metabolic rates of the Hysex Brown and Lohmann Brown crosses chicken embryos as well as on the development of their visceral organs and the incubation effectiveness itself. Currently, most of the research is devoted to studying the influence of variable egg incubation temperatures while using one cross of chickens and comparison with the standard incubation mode. A necessary condition for the balanced development of productive bird embryos is the acquisition of knowledge about their morphophysiological parameters and metabolic needs, based on which it is possible to adjust regimes of artificial egg incubation. The research results have shown that the developed and tested incubation regime with variable temperatures is most effective for hen eggs of the Lohmann Brown cross compared to the Hysex Brown cross. This positive effect was expressed in a more intensive growth of chicken embryos and the development of some visceral organs (gizzard stomach, spleen), as well as in the most pronounced rate of gas exchange (CO2), the highest energy value of embryos and the lowest total energy consumption for growth and metabolism in the period from 4 days of incubation to the hatching time. Differentiation of the temperature regime during embryogenesis has a positive effect on incubation results. The percentage of withdrawal of the Lohmann Brown cross young chickens is 4% higher than that of the Hysex Brown cross due to decreased embryonic mortality and decreased number of frozen embryos and suffocated chickens. This kind of research, in our opinion, is an auspicious one, and it is necessary to adjust the existing incubation regimes of hen eggs in various production areas.

Exhaust Emissions and Energy Consumption Analysis of Conventional, Hybrid, and Electric Vehicles in Real Driving Cycles

One of the environmental aims of the European Union is to achieve climate neutrality by 2050. According to European Parliament data, transport emissions accounted for about 25% of global carbon dioxide emissions in 2016, in which road transport had the largest share (approximately 72%). This phenomenon is particularly visible in urban agglomerations. The solution examples are the popularization of hybrid vehicles and the development of electromobility. The aim of this paper is an assessment of the energy consumption and exhaust emissions from passenger cars fitted with different powertrains in actual operation. For the tests, passenger cars with conventional engines of various emission classes were used as well as the latest hybrid vehicles and an electric car. It enabled a comparative assessment of the energy consumption under different traffic conditions, with particular emphasis on the urban phase and the entire RDE (Real Driving Emissions) test. The results were analyzed to identify changes in these environmental factors that have occurred with the technical advancement of vehicles. The lowest total energy consumption in real traffic conditions is characteristic of an electric vehicle; the plug-in hybrid vehicle with a gasoline engine is about 10% bigger, and the largest one is a combustion vehicle (30% bigger than an electric vehicle). These data may contribute to the classification of vehicles and identification of advantages of the latest developments in conventional, hybrid, and electric vehicles.

Comparison of Different Synthesis Schemes for Production of Sodium Methoxide from Methanol and Sodium Hydroxide

This research investigates the process simulation of sodium methoxide (NaOCH3) synthesis from methanol (CH3OH) and sodium hydroxide (NaOH) under three synthesis schemes: schemes A, B, and C. Scheme A consisted of one equilibrium reactor and two distillation columns, scheme B one reactive distillation column and one distillation column, and scheme C one reactive distillation column and pervaporation membrane. The simulation parameters included CH3OH/NaOH feed flow ratio (1.2-1.6), number of stages (5-30), bottom flow rate (1400-1600 kg/h), and feed stage location (5, 10, 15, 20, 21, 22, 23, and 24). The simulation parameters were varied to determine the optimal NaOCH3 synthetic conditions under different schemes with 0.01 wt% water content, maximum 45 wt% NaOCH3, and the lowest total energy consumption. The results showed that scheme C had the lowest total energy consumption (34.25 GJ/h) under the optimal synthetic condition of 1.4 for CH3OH/NaOH feed flow ratio, 25 for the number of stages, 1550 kg/h for the bottom flow rate, and the 24th feed stage location, with the NaOCH3 flow rate of 675 kg/h. Scheme C thus holds promising potential as an energy-efficient alternative for synthesis of NaOCH3. The novelty of this research lies in the use of pervaporation membrane in place of distillation column to separate CH3OH from water and to lower energy consumption and capital cost.