Additional Energy Consumption Research Articles

Fault Diagnosis of Centrifugal Chiller Based on Extreme Gradient Boosting

Centrifugal chillers have been widely used in medium- and large-scale air conditioning projects. However, equipment running with faults will result in additional energy consumption. Meanwhile, it is difficult to diagnose the minor faults of the equipment. Therefore, the Extreme Gradient Boost (XGBoost) algorithm was used to solve the above problem in this article. The ASHRAE RP-1043 dataset was employed for research, utilizing the feature splitting principle of XGBoost to reduce the data dimension to 23 dimensions. Subsequently, the five important parameters of the XGBoost algorithm were optimized using Multi-swarm Cooperative Particle Swarm Optimization (MSPSO). The minor fault diagnosis model, MSPSO-XGBoost, was established. The results show that the ability of the proposed MSPSO-XGBoost model to diagnose eight different states is uniform, and the diagnostic accuracy of the model reaches 99.67%. The accuracy rate is significantly improved compared to that of the support vector machine (SVM) and back propagation neural network (BPNN) diagnostic models.

Magnetic Mn‐Incorporated Cs3Cu2Br5 Nanocrystals for Spin‐Polarized Enhanced Photocatalytic Biomass Conversion Coupled with H2O2 Evolution

AbstractCopper‐based halide perovskite, as an ideal alternative to lead‐based halide perovskite, has attracted much attention in many applications owing to its earth‐abundant element, non‐toxicity, and excellent optical properties. In this report, magnetic Mn‐incorporated lead‐free copper halide perovskite (Cs3Cu2Br5) nanocrystal (NC) is for the first time designed and prepared using a one‐pot hot‐injection route, resulting in a new emission band at ≈540 nm accompanied with self‐trapped exciton (STE) emission centered at ≈445 nm from Cs3Cu2Br5 NC. In situ X‐ray photoelectron spectroscopy and in situ kelvin probe force microscopy (KPFM) confirm that the Mn2+ incorporation causes efficient electron–hole separation and extended charge lifetime in Mn‐doped Cs3Cu2Br5 NC, which exhibits significantly raised selectively photocatalytic biomass conversion coupled with obviously enhanced H2O2 evolution. With an external magnetic field, the spin‐polarized electrons in Mn‐doped Cs3Cu2Br5 NC arouses reduced charge recombination and more available electrons/holes for surface redox reaction, further raising the photocatalytic performance. This is confirmed by in situ steady‐state/transient‐state photoluminescence (PL) spectroscopy, in situ transient photocurrent measurement, and in situ electrochemical impedance spectroscopy with external magnetic field. In situ electron paramagnetic resonance (EPR) spectra reveal the radical‐involved reaction pathway for biomass conversion. This research exhibits the great potential of spin‐polarization‐enhanced photocatalysis by an external magnetic field without additional energy consumption.

Transparent radiative cooling cover window for flexible and foldable electronic displays

Transparent radiative cooling holds the promise to efficiently manage thermal conditions in various electronic devices without additional energy consumption. Radiative cooling cover windows designed for foldable and flexible displays could enhance cooling capacities in the ubiquitous deployment of flexible electronics in outdoor environments. However, previous demonstrations have not met the optical, mechanical, and moisture-impermeable criteria for such cover windows. Herein, we report transparent radiative cooling metamaterials with a thickness of 50 microns as a cover window of foldable and flexible displays by rational design and synthesis of embedding optically-modulating microstructures in clear polyimide. The resulting outcome not only includes excellent light emission in the atmospheric window under the secured optical transparency but also provides enhanced mechanical and moisture-impermeable properties to surpass the demands of target applications. Our metamaterials not only substantially mitigate the temperature rise in heat-generating devices exposed to solar irradiance but also enhance the thermal management of devices in dark conditions. The light output performance of light-emitting diodes in displays on which the metamaterials are deployed is greatly enhanced by suppressing the performance deterioration associated with thermalization.

RSMA-aided V2X communications: A multi-layer perspective

Rate-splitting multiple access (RSMA), a novel technology in next-generation mobile communications, has garnered increasing attention for its powerful and flexible interference management when compared to traditional multiple access methods. However, considering classical vehicle-to-everything (V2X) communication networks with multiple cells, the flexibility of decoding increases with an increasing number of users having different requests, which results in higher outage performance and additional energy consumption. In order to address these problems, this paper proposes a novel multi-layer (ML) RSMA scheme, aiming to enhance the system performance and decrease the decoding flexibility simultaneously. For the first layer, users enjoying optimal quality of service (QoS) are selected to aid the other cluster members. For the second layer, the cluster members are grouped following the QoS and request similarity. In addition, with respect to our proposed ML-V2X RSMA system, this paper investigates the performance over Rayleigh fading channels, where we derive closed-form expressions of achievable sum rate and outage probability, respectively. Numerical results reveal that: (1) For low SNR scenarios, the ML-V2X RSMA system achieves higher achievable sum rates than classical NOMA-aided V2X systems. (2) The outage probability of ML-V2X RSMA system is superior to that of NOMA-aided V2X systems and traditional cooperative communication systems.

Robust Enhancement of Direct Air Capture of CO2 Efficiency Using Micro-Sized Anion Exchange Resin Particles

In the quest to mitigate carbon dioxide emissions, it becomes essential to address the existing atmospheric CO2. Effective and economical methodologies, particularly those without additional energy consumption, are crucial. Currently, a leading method is the direct capture of CO2 using ion exchange resins, which achieve the adsorption and desorption of carbon dioxide simply by using the humidity variations. This technology, though minimizing additional energy cost, still needs improvement in its efficiency in CO2 capture capacity and compared to other methods. In this work, we develop low-cost techniques to reduce the AmberLite™ IRA900 Cl (IRA-900) anion exchange resin to micro size, and observe significant performance enhancement on CO2 capture efficiency contingent on reducing the particle diameters. This performance disparity is attributed to the differential water adsorption capacities inherent in particles of diverse diameters. Our results reveal that smaller resin particles outperform their larger counterparts, exhibiting accelerated adsorption rates and expedited transitions from wet to dry states. Notably, these smaller particles display a quintupled enhancement in adsorption efficacy relative to non-treated particles and a marked increase in relative adsorption capacity. Upon treatment, IRA-900 demonstrates robust CO2 processing efficiency, achieving a peak adsorption rate of 1.28 g/mol·h and a maximum desorption rate of 1.18 g/mol·h. Also, the material is subjected to almost 100 cycles of testing, and even after 100 cycles, the resin particles maintain a capacity of 100%. Moreover, our material can be fully regenerated to 100% efficiency by simply immersing it in water. Simultaneously, storing it in water allows for the long-term maintenance of its performance without other treatment methods. A key observation is the resin’s sustained performance stability post extended exposure to humid conditions. These outcomes offer substantial practical implications, emphasizing the relevance of our study in practical environmental applications.

Grain size prediction for stainless steel fabricated by material extrusion additive manufacturing

Most traditional powder melting-based additive manufacturing (AM) technologies generally yield high-performance parts at the expense of additional cost and energy consumption. As an economical and efficient alternative method, material extrusion (ME) that deploys polymer-based filaments with highly filled metal particles offers the possibility of scalable, low-cost fabrication of metal components. As a critical step, sintering governs the mechanical strength and geometry of the final parts. The grain growth behavior induced during sintering should be well controlled to achieve the parts with the desired mechanical performance. Due to the nature of AM, grain growth kinetics could also involve extremely complex grain boundary migration and atomic diffusion mechanisms caused by the heterogeneous pore distribution. In this work, an analytical model was developed to predict and understand the grain growth behavior of stainless steel (SS) 316L built by ME-based sintering-assisted AM. Such a model accounts for anisotropic viscosity parameters calibrated through a three-dimensional dilatometry test, enabling the prediction of grain size evolution during sintering. Grain growth kinetic parameters were further identified by the grain size data at the heating and holding stages. To validate and generalize the model, we also conducted the grain size evolution prediction under different sintering temperature profiles for as-built SS 316L specimens. This work will provide scientific insights into the grain growth behavior of metal parts built by this AM technique and its understanding can be readily transferred to other sintering-assisted AM processes like binder jetting and ink writing for metal structure creation.

The energy-saving effect of early-stage autonomous vehicles: A case study and recommendations in a metropolitan area

This paper presents the energy-saving potential of early-stage autonomous vehicles (AVs) by analyzing empirical AV driving records from a public road test. Vehicle-specific power-based microscopic energy consumption models are used to estimate the energy efficiency of the tested AVs, including light-duty vehicles and heavy-duty trucks. Overall, AVs do not necessarily save energy, largely depending on driving scenarios, such as traffic conditions and road types. On expressways, autonomous driving (AD) has an insignificant energy-saving effect (within 10 %) due to similar characteristics to human driving (HD). On urban roads with lower traffic speeds and more interventions from surrounding traffic, AD performs higher energy efficiency due to its capability to accelerate more smoothly by up to 60 %; however, frequent human disengagement generates additional energy consumption of 8%–40 %, especially on urban arterials. We further assessed the marginal effect of trip average speed and AD ratio on energy efficiency, illustrating varied relationships for different driving scenarios and power types. The study suggests a more moderate AD acceleration to elevate the energy-saving effect. Nevertheless, applying AD can hardly reduce the energy of early-stage AVs; instead, control methods to maintain an appropriate speed of the mixed traffic flow can help decrease the total energy consumption.

Reducing the level of infrared radiation of a ground vehicle during its movement

Problem. Reducing the visibility of a ground vehicle makes it possible to increase its survivability and provide conditions for the performance of assigned tasks. The development of approaches to the analysis of the conditions for the formation of a heat trace from the engine of the ground vehicle is an extremely important scientific and practical task. Goal. The purpose of the work was to carry out comparative numerical modelling to assess the effectiveness of diluting the EG flow of the engine of the ground vehicle with atmospheric air to reduce their temperature. Methodology. Using the method of finite volumes, a comparative numerical experiment was conducted in a three-dimensional stationary setup. The possibility of sucking atmospheric air with the standard nozzle of the ejector was quantified. Results. The study shows that the addition of atmospheric air can effectively reduce the temperature of exhaust gases. The use of a regular ejection system allows to reduce the temperature of exhaust gases by 10-12 degrees without additional energy consumption. Originality. Using the method of a comparative numerical experiment, the effectiveness of adding atmospheric air to the exhaust gases of a diesel engine in order to suppress the heat trace was evaluated. Practical value. An approach to reducing the temperature of the exhaust gases of the ground vehicle engine is proposed, that allows to decrease its visibility in the infrared radiation spectrum without additional energy consumption.

Novel photoelectrocatalytic system of oxygen vacancy-rich black TiO2-x nanocones photoanode and natural air diffusion cathode for efficient water purification and simultaneous H2O2 production

Photoelectrocatalytic (PEC) system harnesses solar energy for chemical reactions, representing a highly promising renewable energy-based technology for water purification. Herein, we design a novel separated PEC system that integrates water purification on an oxygen vacancy-rich black TiO2 nanocones (b-TiO2-x) photoanode with two-electron O2 reduction reaction for H2O2 production on a natural air diffusion cathode. This integration benefits from thermodynamic advantages, synergy effects and enhanced •OH production, thus exhibiting superior water purification (98.32%, 0.064 min−1) and H2O2 production (6.83 μmol/h/cm2) at ultra-low applied cell voltage of 0.5 V, with the energy consumption of only 0.034 kWh/m3 wastewater treated, where the simultaneous production of value-added H2O2 could fully compensate for the electric cost of the system. Notably, even under real sunlight irradiation, this system achieves efficient water purification and H2O2 production without additional energy consumption, offering a cost-effective and environmental-benign strategy for the dual purpose of water purification and resourcization.

Pyro-catalysis for refrigerator disinfection via ubiquitous temperature fluctuation

Bacteria breeding in refrigerators can greatly compromise the quality and shelf life of stored food, posing a serious concern. The utilization of disinfection treatments, including ultraviolet irradiation, ozone, and precious metal ions, in refrigerators is constrained by the risk of secondary contamination and the associated high costs. To tackle this matter, we developed a pyro-catalytic disinfection technology that takes advantage of ubiquitous temperature fluctuations to trigger the generation of highly cytotoxic reactive oxygen species for antibacterial. By subjecting the synthesized Ba0.68Sr0.32TiO3 (BST) nanowires or composite patches (BST@C) to temperature fluctuations ranging from 5 to 25 °C for 40 cycles, the survival rates of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were found to be below 5%. More importantly, the survival rates of S. aureus and E. coli were reduced to 19% and 34%, respectively, after only 80 refrigerator opening-closing cycles. This effective demonstration highlights the potential of the safety pyro-catalytic disinfection technology, which does not require additional energy consumption, and exhibits great compatibility with refrigerators.

Photochromic Thermoelectric Smart Window for Season‐Adaptive Solar Heat and Daylight Management

AbstractPhotochromic smart windows have drawn increasing attention as an approach to improve building energy efficiency and enhance indoor daylight comfort. However, existing photochromic smart windows still block sunlight from entering the room on sunny winter days, causing additional energy consumption for heating. Herein, a dual‐mode smart window is designed with decoupled photo and thermal functions by combining colorless Fe‐doped WO3 photochromic film with window rotation. Based on this, selective heating and cooling of the room between winter and summer is achieved while maintaining the daylight comfort benefits during all seasons. As a proof of concept, the smart window reduces the temperature of a model house by up to 7.9 °C in summer mode, while in winter mode the temperature is only reduced by 0.7 °C. The proposed seasonally adaptive dual‐mode smart window obtains by window rotation overcomes the limitations of conventional photochromic smart windows, which not only achieves better energy efficiency but also retains improved daylight comfort. Furthermore, it demonstrates that the heat absorbed by the smart window can be harnessed to produce electricity through the integration of thermoelectric modules within the glazing, which enhances its impact on reducing energy consumption.

High-efficiency metal-free electro-Fenton system on oxygenated graphene-based floating electrodes

Metal-free electro-Fenton (EF) are a promising technology for environmental remediation. This paper reports a novel EF modified with oxygenated graphene aerogel used as a floating electrode for efficient degradation of bisphenol A (BPA) through improved H2O2 yield combined with activation of hydroxyl radical (·OH) production. Impressively, the floating configuration of the electrodes allowed oxygen from the air to diffuse naturally into the reaction interface, reducing additional aeration energy consumption. The current efficiency of the floating system for H2O2 production was 40 times higher than the conventional vertical mode. The pollutant degradation trend exhibited a positive correlation with the ·OH production performance of the electrode. The modified catalyst system achieved the highest ·OH yield of 76.48 μM within 60 min, which was 2.72 times greater than that of the catalyst-free (28.10 μM) and 2.06 times higher than that of the unmodified catalyst (37.19 μM). Experiments and theoretical calculations indicated that the oxygen-containing functional groups introduced the graphene skeleton created new sites for in situ activation of electrogenerated H2O2, resulting in increased ·OH production. The primary activation sites were identified as the = O and –COOH groups, with the = O edges playing a particularly significant role. This system offers long-lasting stability and avoids secondary pollution, making it ideal for green environmental remediation compared to the traditional EF process.

The effect of aeration mode (intermittent vs. continuous) on nutrient removal and greenhouse gas emissions in the wastewater treatment plant of Corleone (Italy)

The paper reports the results of an experimental study aimed at comparing two configurations of a full-scale wastewater treatment plant (WWTP): conventional activated sludge (CAS) and oxic-settling-anaerobic process (OSA) with intermittent aeration (IA). A comprehensive monitoring campaign was carried out to assess multiple parameters for comparing the two configurations: carbon and nutrient removal, greenhouse gas emissions, respirometric analysis, and sludge production. A holistic approach has been adopted in the study with the novelty of including the carbon footprint (CF) contribution (as direct, indirect and derivative emissions) in comparing the two configurations. Results showed that the OSA-IA configuration performed better in total chemical oxygen demand (TCOD) and ortho-phosphate (PO4-P) removal. CAS performed better for Total Suspended Solids (TSS) removal showing a worsening of settling properties for OSA-IA. The heterotrophic yield coefficient and maximum growth rate decreased, suggesting a shift to sludge reduction metabolism in the OSA-IA configuration. Autotrophic biomass showed a reduced yield coefficient and maximum growth yield due to the negative effects of the sludge holding tank in the OSA-IA configuration on nitrification. The OSA-IA configuration had higher indirect emissions (30.5 % vs 21.3 % in CAS) from additional energy consumption due to additional mixers and sludge recirculation pumps. The CF value was lower for OSA-IA than for CAS configuration (0.36 kgCO2/m3 vs 0.39 kgCO2/m3 in CAS).

PRICELESS: Privacy enhanced AI‐driven scalable framework for IoT applications in serverless edge computing environments

AbstractServerless edge computing has emerged as a new paradigm that integrates the serverless and edge computing. By bringing processing power closer to the edge of the network, it provides advantages such as low latency by quickly processing data for time‐sensitive Internet of Things (IoT) applications. Additionally, serverless edge computing also brings inherent problems of edge and serverless computing such as cold start, security and privacy that are still waiting to be solved. In this paper, we propose a new Blockchain‐based AI‐driven scalable framework called PRICELESS, to offer security and privacy in serverless edge computing environments while performing cold start prediction. In PRICELESS framework, we used deep reinforcement learning for the cold start latency prediction. For experiments, a cold start dataset is created using a heart disease risk‐based IoT application and deployed using Google Cloud Functions. Experimental results show the additional delay that the blockchain module brings to cold start latency and its impact on cold start prediction performance. Additionally, the performance of PRICELESS is compared with the current state‐of‐the‐art method based on energy cost, computation time and cold start prediction. Specifically, it has been observed that PRICELESS causes 19 ms of external latency, 358.2 watts for training, and 3.6 watts for prediction operations, resulting in additional energy consumption at the expense of security and privacy.

A Polymer Nanocomposite with Strong Full-Spectrum Solar Absorption and Infrared Emission for All-Day Thermal Energy Management and Conversion.

Realizing efficient energy utilization from the heat source of the sun and the cold source of outer space is of great significance for addressing the global energy and environmental crisis. Materials with ideal full-spectrum solar absorption and infrared emission are highly desirable for adapting to the continuous weather dynamic throughout the day, nonetheless, their development remains challenging. Here, a polymer nanocomposite with full-spectrum strong solar (280-2500nm) absorption ranging from 88.8% to 94.8% with an average value of 93.2% and full-spectrum high infrared (8-13µm) emission ranging from 81.3% to 90.0% with an average value of 84.2%, is reported by melt-processing polypropylene and uniformly dispersed low-loading MXene nanosheets (1.9 vol%). The nanocomposite can achieve daytime photothermal enhancement of ≈50 °C and nighttime radiative cooling of 8 °C. The temperature difference throughout the day ensures all-day uninterrupted thermoelectric generation, yielding a power density output of 1.5W m-2 (daytime) and 7.9mW m-2 (nighttime) in real outdoor environment without any additional energy consumption. This work provides an impressive polymer nanocomposite with ideal full-spectrum solar absorption and infrared emission for all-day uninterrupted thermal energy management and conversion.

Sustainability assessment of electron beam melted Ti6Al4V machining: energy consumption and lubricant use

ABSTRACT Electron Beam Melting (EBM) is typically used to produce high performance titanium parts, but it falls short in ensuring the high surface finishing always requested for aerospace applications, and this leads to the need of a post-building finishing resulting in additional resources and energy consumption. An optimization of the post-processing is necessary and the literature lacks guidelines in this regard. In this study, 18 cylindrical samples were produced by EBM and then postprocessed by wet and dry turning by using the same process parameters. Surface roughness, tool wear rate, specific cutting energy and energy consumption were investigated and compared to understand the best compromise to remove the same total depth of cut (2.4 mm). Results showed that dry turning can result in saving up 9% in total energy consumption. Also, feed rate and depth of cut can be varied by fixing the spindle speed without significantly affecting surface roughness by saving up to 73% in total energy consumption.

Rapid synthesis of phosphor-glass composites in seconds based on particle self-stabilization

Phosphor-glass composites (PGC) are excellent candidates for highly efficient and stable photonic converters; however, their synthesis generally requires harsh procedures and long time, resulting in additional performance loss and energy consumption. Here we develop a rapid synthetic route to PGC within about 10 seconds, which enables uniform dispersion of Y3Al5O12:Ce3+ (YAG:Ce) phosphor particles through a particle self-stabilization model in molten tellurite glass. Thanks for good wettability between YAG:Ce micro-particles and tellurite glass melt, it creates an energy barrier of 6.94 × 105 zJ to prevent atomic-scale contact and sintering of particles in the melt. This in turn allows the generation of YAG:Ce-based PGC as attractive emitters with high quantum efficiency (98.4%) and absorption coefficient (86.8%) that can produce bright white light with luminous flux of 1227 lm and luminous efficiency of 276 lm W−1 under blue laser driving. This work shows a generalizable synthetic strategy for the development of functional glass composites.

Heat dissipation performance research of battery modules based on composite phase change materials cooling and electrochemical thermal coupling model

In order to improve electric vehicle lithium-ion batteries (LIBs) performance and increase cycle life, it is crucial to design a reliable and efficient battery thermal management system (BTMS). Compared with other active battery cooling methods, passive phase change material (PCM) cooling has the advantages of simple structure, good temperature control uniformity, strong reliability, and no additional energy consumption. This article uses a series of experimental procedures to add expanded graphite to traditional paraffin wax PCM and obtain composite phase change materials (CPCM) with different mixing ratios. A control experiment is created to compare the cooling performance of the CPCM cooling with natural convection cooling, research shows that the cooling performance of CPCM can well meet the cooling demand which maximum temperature and maximum temperature difference of battery modules. In addition, to study the performance of thermal properties parameters related to CPCM, a COMSOL numerical calculation model of battery module based on CPCM cooling and electrochemical thermal coupling model is established. The effectiveness and accuracy of the model are verified through heat generation experiments at different rates (0.5 C, 1 C, 1.5 C), with a maximum temperature error of 1.6 K and an error accuracy of less than 0.6%. Subsequently, the performance of phase change temperature, thermal conductivity and phase change latent heat is studied and reasonable value ranges are obtained, which are 312 K∼318 K, 2.5 W /(m·K), and 175 J/g∼200 J/g, respectively.

Development of Virtual Sensor Based on LSTM-Autoencoder to Detect Faults in Supply Chilled Water Temperature Sensor

Supply chilled water temperature (SCWT) is an important variable for the efficient and stable operation of heating, ventilation, and air conditioning (HVAC) systems. A precisely measured value ensured by the continuous reliability of the temperature sensor is essential for optimal control of an HVAC system because temperature sensor faults can affect the chiller operation and waste energy. Therefore, temperature sensor fault-detection strategies are imperative for maintaining a comfortable indoor thermal environment and ensuring the efficient and stable operation of HVAC systems. This study proposes a fault-detection method for an SCWT sensor using a virtual sensor based on a long short-term memory-autoencoder. The fault-detection performance is evaluated considering a case study under various sensor fault scenarios to evaluate changes in indoor thermal comfort and energy consumption after correcting sensor faults detected by the virtual sensor. The results verify excellent fault-detection performance in various fault scenarios (F-1 scores ranging from 0.9350 to 1.000). After correcting the SCWT fault, indoor thermal comfort is steadily maintained without additional energy consumption (indoor set-point temperature unmet hour reduced by a maximum of 105.7 hours, and energy consumption decreased by up to 1.8%).

Manipulation of Convection Using Infrared Light Emitted from Human Hands.

Control of convection plays an important role in heat transfer regulation, bio/chemical sensing, phase separation, etc. Current convection controlling systems generally depend on engineered energy sources to drive and manipulate the convection, which brings additional energy consumption into the system. Here the use of human hand as a natural and sustainable infrared (IR) radiation source for the manipulation of liquid convection is demonstrated. The fluid can sense the change of the relative position or the shape of the hand with the formation of different convection patterns. Besides the generation of static complex patterns, dynamic manipulation of convections can also be realized via moving of hand or finger. The use of such sustainable convections to control the movement of a floating "boat" is further achieved. The use of human hands as the natural energy sources provides a promising approach for the manipulation of liquid convection without the need of extra external energy, which may be further utilized for low-cost and intelligent bio/chemical sensing and separation.