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Although several research studies have adopted specific energy consumption (SEC) as an indicator of the progress of improved energy efficiency, publications are scarce on critical assessments when using SEC. Given the increasing importance of monitoring improved industrial energy efficiency and the rising popularity of SEC as an energy key performance indicator (e-KPI), an in-depth analysis and problematization on the pros and cons of using SEC would appear to be needed. The aim of this article is to analyse SEC critically in relation to industrial energy efficiency. By using SEC in the pulp and paper industry as an example, the results of this exploratory study show that although SEC is often used as an e-KPI in industry, the comparison is not always straightforward. Challenges emanate from a lack of information about how SEC is calculated. It is likely that SEC is an optimal e-KPI within the same study, when all deployed SECs are calculated in the same way, and with the same underlying assumptions. However, before comparing SEC with other studies, it is recommended that the assumptions on which calculations are based should be scrutinized in order to ensure the validity of the comparisons. The paper remains an important contribution in addition to the available handbooks.

The objective of this research was to assess the energy consumption of wastewater treatment plants (WWTPs), to apply a mathematical model to evaluate their carbon footprint, and to propose energy saving strategies that can be implemented to reduce both energy consumption and greenhouse gas (GHG) emissions in Greece. The survey was focused on 10 WWTPs in Greece with a treatment capacity ranging from 10,000 to 4,000,000 population equivalents (PE). Based on the results, annual specific energy consumption ranged from 15 to 86 kWh/PE. The highest energy consumer in all the WWTPs was aeration, accounting for 40–75% of total energy requirements. The annual GHG emissions varied significantly according to the treatment schemes employed and ranged between 61 and 161 kgCO2e/PE. The highest values of CO2 emissions were obtained in extended aeration systems and the lowest in conventional activated sludge systems. Key strategies that the wastewater industry could adopt to mitigate GHG emissions are identified and discussed. A case study is presented to demonstrate potential strategies for energy savings and GHG emission reduction. Given the results, it is postulated that the reduction of dissolved oxygen (DO) set points and sludge retention time can provide significant energy savings and decrease GHG emissions.

This study investigates the influence of design, relative density (RD), and carbon fiber (CF) incorporation parameters on mechanical characteristics, including compressive modulus (E), strength, and specific energy absorption (SEA) of triply periodic minimum surface (TPMS) lattice structures. The TPMS lattices were 3D-printed by fused filament fabrication (FFF) using polylactic acid (PLA) and carbon fiber-reinforced PLA(CFRPLA). The mechanical properties of the TPMS lattice structures were evaluated under uniaxial compression testing based on the design of experiments (DOE) approach, namely, full factorial design. Prediction modeling was conducted and compared using mathematical and intelligent modeling, namely, adaptive neuro-fuzzy inference systems (ANFIS). ANFIS modeling allowed the 3D printing imperfections (e.g., RD variations) to be taken into account by considering the actual RDs instead of the designed ones, as in the case of mathematical modeling. In this regard, this was the first time the ANFIS modeling utilized the actual RDs. The desirability approach was applied for multi-objective optimization. The mechanical properties were found to be significantly influenced by cell type, cell size, CF incorporation, and RD, as well as their combination. The findings demonstrated a variation in the E (0.144 GPa to 0.549 GPa), compressive strength (4.583 MPa to 15.768 MPa), and SEA (3.759 J/g to 15.591 J/g) due to the effect of the studied variables. The ANFIS models outperformed mathematical models in predicting all mechanical characteristics, including E, strength, and SEA. For instance, the maximum absolute percent deviation was 7.61% for ANFIS prediction, while it was 21.11% for mathematical prediction. The accuracy of mathematical predictions is highly influenced by the degree of RD deviation: a higher deviation in RD indicates a lower accuracy of predictions. The findings of this study provide a prior prediction of the mechanical behavior of PLA and CFRPLA TPMS structures, as well as a better understanding of their potential and limitations.

BACKGROUND AND OBJECTIVES: Energy efficiency plays a crucial role in the success and sustainability of desalination technologies. Energy considerations are intricately linked with every aspect of planning, management, and operation in water desalination. This study aims to evaluate and enhance energy requirements, energy efficiency, and the economic feasibility of the Hashemite University photovoltaic brackish water reverse osmosis desalination plant at Hashemite University. METHODS: This study's aims were achieved by conducting an energyaudit and detailed assessment to identify the energy efficiency considerations that should be integrated into the facility's planning, management, and operation strategies. To ensure accurate and reliable data collection and enable a comprehensive analysis of the plant's energy performance, portable energy analyzers and loggers were employed to measure energy consumption, and measurements and verification techniques were recommended and implemented to establish the required baseline. A regression model was utilized to determine the potential energy savings resulting from energy conservation measures. This involved determining the expected savings by calculating the area between two curves: the new actual consumption of the brackish water reverse osmosis plant after implementing energy conservation measures and the curve generated by the model representing the usual consumption in the absence of energy conservation measures. FINDINGS: This study underscores the challenges faced by desalination, particularly regarding intensive energy consumption. It also presents innovative ways to achieve sustainability by emphasizing energy efficiency, integrating renewable energy, and advocating for a holistic water management approach. It was determined that the maximum specific energy consumption of the Hashemite University photovoltaic brackish water reverse osmosis plant was 0.625 kilowatts per cubic meter. This reflects the actual consumption and energy performance of the plant, which was found to be 192 percent more efficient than the estimated specific energy and 144 percent more efficient than the calculated specific energy. No energy conservation measures were implemented at this stage, as the plant was already operating efficiently. The measured data shall be considered as a baseline for future investigations and monitoring and evaluation of the plant. Many challenges were identified during the current work, including the low quality of raw water and minimal demand for freshwater, which resulted in lower operation hours outside of sun peak hours, while the direct utilization of photovoltaic energy is recommended. CONCLUSION: Renewable energy and energy recovery were recognized as potential sources for energy savings to achieve sustainable and long-term feasible operation and cost recovery at the Hashemite University photovoltaic brackish water reverse osmosis plant. The feasibility of the plant showed a fast payback period of up to 1.1 years. Utilizing clean solar photovoltaic energy to power the brackish water reverse osmosis plant led to a considerable reduction of greenhouse gases (mainly carbon dioxide). The estimated amount of carbon dioxide reduction during the project's lifetime was 1,289,600 kilograms. The integration of solar energy showed promise for further enhancing energy efficiency and sustainability. This study contributes to making the desalination sector more environmentally friendly and economically viable, which is of paramount importance in addressing global water scarcity concerns.

A novel auxetic honeycomb (RSSHR) is developed by introducing the arc-shaped structure into the re-entrant star-shaped honeycomb (RSSH). Based on theoretical models and finite element methods, the dynamic crushing responses of RSSH and RSSHR plate (RSSH_P and RSSHR_P) structures are investigated to elucidate the dependence of plateau stress, negative Poisson’s ratio (NPR), deformed shape and specific energy absorption (SEA) on crushing velocity. The stress–strain curves of two types of structures are calculated to analyze configuration–mechanical property relationships. The results exhibit that the plateau stress and SEA of the RSSH_P and RSSHR_P structures increase as the crushing velocity increases. Owing to the stress-mitigating effect of the arc-shaped structure, the RSSHR_P structure exhibits a stronger NPR effect. And the SEA of the RSSHR_P structure is higher than that of the RSSH_P structure. In addition, it is also found that at low crushing velocity, the stress–strain curves of the two structures exhibit three distinct stages: the elastic stage (I), the stress plateau stage (II) and the densification stage (III). During the crushing process, there are three deformed shapes. They are the global deformed shape, the local deformed shape and the layer-by-layer deformed shape.

This study investigated the effect of repeated blasting on the stability of surrounding rock during the construction of a tunnel or city underground engineering. The split Hopkinson pressure bar (SHPB) was used to carry out cyclic impact tests on granite samples, each having a circular hole, under different axial pressures, and the cumulative specific energy was proposed to characterize the damage characteristics of the rock during the cyclic impact. The mechanical properties and the energy absorbed by the granite samples under cyclic impact loads were analyzed. The results showed that under different axial pressures, the reflected waveform from the samples was characterized by “double-peak” phenomenon, which gradually changed to “single-peak” with the increase in damage value. The dynamic peak stress of the sample first increased and then decreased with an increase in impact times. The damage value criterion established based on the energy dissipation could well characterize the relationship between the damage and the number of impacts, which showed a slow increase, steady increase, and high-speed increase, and the damage value depended mainly on the last impact. Under the action of different axial pressures, all the failure modes of the samples were axial splitting failures. As the strain rate increased, with an increase in the dimension of the block, the sizes of the rock fragments decreased, and the fragmentation became more severe.

This study introduces a new method for fabricating biphasic architectured structures using self-developed hybrid material extrusion (MEX) process. This approach involves filling the voids of closed-cell structures with a powder material in a single process. The architectured structures were 3D printed using thermoplastic polyurethane (TPU) and subsequently filled with polyamide 12 (PA12) powder in two distinct configurations: partially filled (50%) and fully filled (100%), named as biphasic architectured structures. Experimental and numerical uniaxial quasistatic compression tests were conducted on partially filled and fully filled local and global closed-cell architectured structures, and their results were compared with those of empty architectured structures. The comparative analysis revealed that the partially filled structures, representing a transitional phase, exhibit enhanced properties which is influenced by the amount of powder filling within the structure. A substantial enhancement in stiffness and specific energy absorption (SEA) was observed in the consolidation phase. The fully filled architectured structures exhibit rapid increase in its loading response, characterized by high stiffness and SEA. Furthermore, this study paves the way for future exploration into strategic filling of multiple powders in different regions, thereby tailoring the mechanical and functional responses. Potential applications include manufacturing components and equipment that absorb energy, provide impact protection, and offer vibration damping and soundproofing capabilities.

This study explores the existing literature on specific energy consumption (SEC) use for paddy drying and consolidates all relevant data for comparisons across technologies. Energy consumption data for a range of drying technologies are consolidated from published literature and normalized to enable comparison. A large proportion of the source data are generated from operational performance in industrial or laboratory settings, while the remainder is derived from computer simulations. The SEC of paddy drying is driven primarily by technology type; however, operational factors (such as the system size, temperature, and airflow) and external factors (such as the local climate and paddy moisture content) also heavily influence system energy use. The results of our analysis show that the industrial drying technologies explored in this study have an average SEC of 5.57 ± 2.21 MJ/kg, significantly lower than the 20.87 ± 14.97 MJ/kg observed in a laboratory setting, which can potentially be attributed to differences in processing capacity. Multi-stage drying typically has higher energy efficiency when tempering stages are incorporated. The self-circulating design of some drying systems may provide additional opportunities for heat exchange, leading to efficient drying performance without the need for a separate tempering stage. Beyond traditional methods, we have observed a notable shift towards solar-assisted and infrared drying technologies in laboratory settings, reflecting an increasing interest in sustainable and efficient drying solutions. In summary, this review consolidates SEC data for rice drying technologies, analyzes the energy intensity and performance of each drying technology, and identifies data gaps that might be addressed in future research.

A novel energy-absorbing structure, the Koch hierarchical honeycomb, which combines the Koch geometry with a conventional honeycomb structure, is proposed in this work. Adopting a hierarchical design concept using Koch has improved the novel structure more than the honeycomb. The mechanical properties of this novel structure under impact loading are studied by finite element simulation and compared with the conventional honeycomb structure. To effectively verify the reliability of the simulation analysis, quasi-static compression experiments were conducted on 3D-printed specimens. The results of the study showed that the first-order Koch hierarchical honeycomb structure increased the specific energy absorption by 27.52% compared to the conventional honeycomb structure. Furthermore, the highest specific energy absorption can be obtained by increasing the hierarchical order to 2. Moreover, the energy absorption of triangular and square hierarchies can be significantly increased. All achievements in this study provide significant guidelines in the reinforcement design of lightweight structures.

A global manufacturing community is dedicatedly striving to implement the concept of NetZero in precision cutting of difficult-to-machine materials, specifically, Inconel 617 (IN617) with due consideration to environmental protocols. The fast strain hardening issue of the said alloy during conventional processing rationalizes the application of electric discharge machining (EDM). However, EDM has been criticized for its high energy consumption and limited cutting efficiency. Moreover, conventional dielectric (kerosene) employed in EDM has drastic environmental and operator health concerns. To address the abovementioned issues, waste cooking oil (WCO) has been employed in this study which enhances the reusability of resources and minimizes the cost of the dielectric. Making the process sustainable is imperative along with continuously escalating scarcity of engineering resources. Therefore, the potential of shallow and deep cryogenically treated electrodes (SCT and DCT) has been comprehensively examined against nanofilled WCO to achieve the aforementioned objective. Three different concentrations of powder ( C p ) and surfactant ( C s ) to uplift the machining responses are investigated through a detailed parametric experimental design. Core machining factors such as material removal rate (MRR), surface roughness (SR), and specific energy consumption (SEC) are examined through optical and electron microscopy studies and 3D surface profilometry. Hereafter, machining factors are modelled using the artificial neural network (ANN) technique. An exceptional improvement of 80%, 25.3%, and 75.16% has been achieved in MRR, SR, and SEC respectively using nanopowder-mixed WCO against SCT brass compared to the responses’ values obtained against conventionally used kerosene. Furthermore, compared to kerosene, the maximum CO 2 reduction of 79.97 ± 11.2% is achieved with WCO.