Hydrogen (H2) has attained significant benefits as an energy carrier due to its gross calorific value (GCV) and inherently clean operation. Thus, hydrogen as a fuel can lead to global sustainability. Conventional H2 production is predominantly through fossil fuels, and electrolysis is now identified to be most promising for H2 generation. This review describes the recent state of the art and challenges on ultra-pure H2 production through methanol electrolysis that incorporate polymer electrolyte membrane (PEM). It also discusses about the methanol electrochemical reforming catalysts as well as the impact of this process via PEM. The efficiency of H2 production depends on the different components of the PEM fuel cells, which are bipolar plates, current collector, and membrane electrode assembly. The efficiency also changes with the nature and type of the fuel, fuel/oxygen ratio, pressure, temperature, humidity, cell potential, and interfacial electronic level interaction between the red... [more]

This work evaluates date palm waste as a cheap and available biomass feedstock in UAE for the production of biofuels. The thermochemical and biochemical routes including pyrolysis, gasification, and fermentation were investigated. Simulations were done to produce biofuels from biomass via Aspen Plus v.10. The simulation results showed that for a tonne of biomass feed, gasification produced 56 kg of hydrogen and fermentation yielded 233 kg of ethanol. Process energy requirements, however, proved to offset the bioethanol product value. For 1 tonne of biomass feed, the net duty for pyrolysis was 37 kJ, for gasification was 725 kJ, and for fermentation was 7481.5 kJ. Furthermore, for 1 tonne of date palm waste feed, pyrolysis generated a returned USD $768, gasification generated USD 166, but fermentation required an expenditure of USD 763, rendering it unfeasible. The fermentation economic analysis showed that reducing the system’s net duty to 6500 kJ/tonne biomass and converting 30% hemic... [more]

A numerical study was carried out to evaluate the influence of engine combustion chamber geometry and operating conditions on the performance and emissions of a homogeneous charge compression ignition (HCCI) engine. Combustion in an HCCI engine is a very complex phenomenon that is influenced by several factors that need to be controlled, such as gas temperature, heat transfer, turbulence and auto-ignition of the gas mixture. An eddy dissipation concept (EDC) combustion model was used to take into account the interaction between turbulence and chemistry. The model assumed that reactions occur in small turbulent structures called fine-scales, whose characteristic lengths and times depend mainly on the turbulence level. The model parameters were slightly modified with respect to the standard model proposed by Magnussen, to correctly simulate the characteristics of the HCCI combustion process. A reduced iso-octane chemical mechanism with 186 species and 914 chemical reactions was employed... [more]

With the tremendous increase of heterogeneous Internet of Things (IoT) devices and the different service requirements of these IoT applications, machine-type communication (MTC) has attracted considerable attention from both industry and academia. Owing to the prominent advantages of supporting pervasive connectivity and wide area coverage, the cellular network is advocated as the potential wireless solution to realize IoT deployment for MTC, and this creative network paradigm is called the cellular IoT (C-IoT). In this paper, we propose the three-layer structured C-IoT architecture for MTC and review the challenges for deploying green C-IoT. Then, effective strategies for realizing green C-IoT are presented, including the energy efficient and energy harvesting schemes. We put forward several strategies to make the C-IoT run in an energy-saving manner, such as efficient random access and barring mechanisms, self-adapting machine learning predictions, scheduling optimization, resource a... [more]

Annual mean wind speed distribution models for power generation based on regional wind resource maps are limited by spatial and temporal resolutions. These models, in general, do not consider the impact of local terrain and atmospheric circulations. In this study, long-term five-year wind data at three sites on the North, East, and West of the Baltimore metropolitan area, Maryland, USA are statistically analyzed. The Weibull probability density function was defined based on the observatory data. Despite seasonal and spatial variability in the wind resource, the annual mean wind speed for all sites is around 3 m/s, suggesting the region is not suitable for large-scale power generation. However, it does display a wind power capacity that might allow for non-grid connected small-scale wind turbine applications. Technical and economic performance evaluations of more than 150 conventional small-scale wind turbines showed that an annual capacity factor and electricity production of 11% and 1... [more]

This paper deals with the study of multi-channel adaptive noise cancellation with a focus on its application in electromagnetic (EM) telemetry. We presented new variable step-size least mean square (LMS) techniques: regularized variable step-size LMS and regularized sigmoid variable size LMS, for electromagnetic telemetry data processing. Considering the complexity and spatial distribution of environmental noise, algorithms with multiple reference signals were used to retrieve transmitted EM signals. The feasibility of the regularized variable step size LMS algorithms with numerical simulation was analyzed and presented. The adaptive processing techniques were applied in the recovery of frequency and binary phase shift key modulated signal. The proposed multi-channel adaptive technique achieves fast convergence speed, low mean squared error and is shown to have good convergence characteristics compared to conventional methods. In addition to attaining good results from the multi-channe... [more]

Different from the design of conventional permanent magnet (PM) motors, high-speed motors are primarily limited by rotor unbalanced radial forces, rotor power losses, and rotor mechanical strength. This paper aimed to propose a suitable PM motor with consideration of these design issues. First, the rotor radial force is minimized based on the selection of stator tooth numbers and windings. By designing a stator with even slots, the rotor radial force can be canceled, leading to better rotor strength at high speed. Second, rotor power losses proportional to rotor frequency are increased as motor speed increases. A two-dimensional sensitivity analysis is used to improve these losses. In addition, the rotor sleeve loss can be minimized to less than 8.3% of the total losses using slotless windings. Third, the trapezoidal drive can cause more than a 33% magnet loss due to additional armature flux harmonics. This drive reflected loss is also mitigated with slotless windings. In this paper, s... [more]

Recent research has enabled the integration of traditional Volt-VAr Control (VVC) resources, such as capacitor banks and transformer tap changers, with Distributed Energy Resources (DERs), such as photo-voltaic sources and energy storage, in order to achieve various Volt-VAr Optimization (VVO) targets, such as Conservation Voltage Reduction (CVR), minimizing VAr flow at the transformer, minimizing grid losses, minimizing asset operations and more. When more than one target function can be optimized, the question of multi-objective optimization is raised. In this work, a general formulation of the multi-objective Volt-VAr Optimization problem is proposed. The applicability of various multi-optimization techniques is considered and the operational interpretation of these solutions is discussed. The methods are demonstrated using a simulation on a test feeder.

Owing to some nonlinear characteristics in the permanent-magnet synchronous motor (SM), such as nonlinear friction, cogging torque, wind stray torque, external load torque, and unmodeled systems, fine control performances cannot be accomplished by utilizing the general linear controllers. Thereby, the backstepping approach adopting three adaptive rules and a swapping function is brought forward for controlling the rotor motion in the permanent-magnet SM drive system to reduce nonlinear uncertainties effects. To improve the chattering phenomenon, the backstepping control with three adaptive rules using a revised recurring sieved Pollaczek polynomials neural network (RRSPPNN) with reformed grey wolf optimization (RGWO) and a recouped controller is proposed to estimate the internal collection and external collection torque uncertainties, and to recoup the smallest fabricated error of the appraised rule. In the light of the Lyapunov stability, the on-line parametric training method of the... [more]

This paper qualitatively evaluates the application of blockchain technology for three energy efficiency use cases. To achieve the Sustainable Development Agenda, energy efficiency improvements have to double by 2030. However, the adoption of energy efficiency interventions is slow due to several market barriers. Blockchain technology is a nascent technology with the potential to address these barriers or even fundamentally change energy system designs, by enabling transparent, decentralised, and tamper-resilient systems. Nevertheless, a blockchain application comes with trade-offs and needs to be considered on a case by case basis. In this paper, we examine the benefits and constraints of a blockchain application for three different approaches to achieving energy efficiency: (i) peer-to-peer (P2P) energy trading; (ii) White Certificate Scheme (WCS); and (iii) Energy Service Companies (ESCOs). For each of these cases, we apply a decision framework to assess blockchain feasibility and ou... [more]

An investigation of electrolyte-assisted hydrogen storage reactions in complex aluminum hydrides (LiAlH4 and NaAlH4) reveals significantly reduced reaction times for hydrogen desorption and uptake in the presence of an electrolyte. LiAlH4 evolves ~7.8 wt% H2 over ~3 h in the presence of a Li-KBH4 eutectic at 130 °C compared to ~25 h for the same material without the electrolyte. Similarly, NaAlH4 exhibits 4.8 wt% H2 evolution over ~4 h in the presence of a diglyme electrolyte at 150 °C compared to 4.4 wt% in ~15 h for the same material without the electrolyte. These reduced reaction times are composed of two effects, an increase in reaction rates and a change in the reaction kinetics. While typical solid state dehydrogenation reactions exhibit kinetics with rates that continuously decrease with the extent of reaction, we find that the addition of an electrolyte results in rates that are relatively constant over the full desorption window. Fitting the kinetics to an Avrami-Erofe’ev mode... [more]

In this publication, the cooling fluid for direct oil-cooled electric traction drive is investigated. A dedicated thermal resistance model was developed in order to show the influence of the fluid properties on the continuous performance. For this purpose, the heat transfer parameters are adjusted in the simulation using an exponential approach in order to evaluate the cooling fluid. In a sensitivity study, density, heat capacity, thermal conductivity, and viscosity are investigated. Because viscosity, within the range investigated, shows the largest percentage deviation from the reference fluid, the greatest effect on performance can be seen here. In order to check the plausibility of the calculated results of the thermal simulation, two fluids were chosen for performance testing on a dedicated electro motor cooling (EMC) test. Beyond the investigation of heat transfer, aging of the defined fluid at maximum heat input over several hours is also evaluated. Only slight changes of the fl... [more]

The interface behavior between a caisson and the surrounding soil plays an important role in the installation of suction caissons as foundations for offshore wind turbines. A series of shear tests were carried out using a modified direct shear apparatus to study the interface shear behavior between sand and concrete. Sand samples with three particle size ranges (0.63−1.25 mm, 1.25−2.5 mm, 2.5−5.0 mm) and concrete plates with different relative roughness were used to explore the influence of the relative roughness parameter (Rn) and mean particle size (D50) on shear behavior. The responses from the pure sand shear test are also discussed for comparison. Test results show that the higher the relative roughness (Rn), the greater the maximum shear stress (τmax) appeared. The interface shear stress was weaker than that of the pure sand test. Furthermore, the interface friction angle (φ) of sand−concrete was closely related to the relative roughness of the concrete surface. Under the same co... [more]

Balancing holes in single-suction centrifugal pumps are generally applied to attenuate the axial thrust caused by a pressure difference between the front side of a shroud and the rear side of a hub of an impeller. The magnetic drive pump, the subject of this study, has a leak-free airtight structure and an integrated structure of the impeller and inner magnet. To prevent the performance degradation of the magnetic drive caused by heat during operation, complex cooling flow paths connected to balancing holes have been designed so that a sufficient amount of coolant would flow around the magnetic drive. Due to this spatial characteristic, when balancing holes are applied to a magnetic drive pump, the balancing hole flow path becomes very long compared to that of balancing holes applied to conventional pumps. When the balancing hole flow path is long, the flow path loss increases, which in turn increases the adverse effect of balancing holes on the pump performance. Therefore, the design... [more]

Spray impingement on smooth and heated surfaces is a highly complex thermofluid phenomenon present in several engineering applications. The combination of phase Doppler interferometry, high-speed visualization, and time-resolved infrared thermography allows characterizing the heat transfer and fluid dynamics involved. Particular emphasis is given to the use of nanofluids in sprays due to their potential to enhance the heat transfer mechanisms. The results for low nanoparticle concentrations (up to 1 wt.%) show that the surfactant added to water, required to stabilize the nanofluids and minimize particle clustering, affects the spray’s main characteristics. Namely, the surfactant decreases the liquid surface tension leading to a larger wetted area and wettability, promoting heat transfer between the surface and the liquid film. However, since lower surface tension also tends to enhance splash near the edges of the wetted area, the gold nanospheres act to lessen such disturbances due to... [more]

This paper presents a virtual model of a scroll compressor developed on the one-dimensional analysis software Simcenter Amesim®. The model is semi-empirical: it needs some physical details of the modelled machine (e.g., the cubic capacity), but, on the other hand, it does not require the geometrical features of the spirals, so it needs experimental data to calibrate it. The model also requires rotational speed and the outlet temperature as boundary conditions. The model predicts the power consumption and the mass flow rate and considers leakages and mechanical losses. After the model presentation, this paper describes the test bench and the obtained data used to calibrate and validate the model. At last, the calibration process is described, and the results are discussed. The calculated values fit the experimental data also in extrapolation, despite the model is simple and performs calculations within 7 s. Due to these characteristics, the model is suitable for being used in a larger m... [more]

The organic fraction of waste is increasingly used for biogas production. However, the fermentation process used for this purpose also produces waste in the form of digestate in addition to biogas. Its liquid fraction can, among other things, be a source of water, but its recovery requires many advanced technological processes. Among the first in the treatment train is usually coagulation/chemical precipitation. Its application changes properties, including the size and zeta potential (ζ) of the fractions that have to be removed in subsequent processes. Changes in particle size distribution and ζ potential occurring in the liquid fraction of municipal waste biogas plant digestate and solutions after coagulation/chemical precipitation with FeCl₃·6H₂O, PIX 112 and CaO were analyzed. The particle size distribution of the raw digestate was wide (0.4−300 µm; up to 900 µm without ultrasound). The median particle diameter was about 12 µm. The ζ potential ranged from −25 to −35 mV in the pH ra... [more]

One of the repeating themes around the provision of the knowledge and skills needed for delivering sustainable communities is the idea of a “common language” for all built environment professionals. This suggestion has been repeated regularly with each new political and professional review within and between different sectors responsible for the delivery of sustainable communities. There have been multiple efforts to address academic limitations, industry fragmentation and promote more interdisciplinary working and sector collaboration. This research explored the role of skills for sustainable communities, particularly within the higher education (HE) sector, and the responses to support the development of a “common language of sustainability” that can be shared between different sectors, professional disciplines and stakeholders. As an interdisciplinary group of academics and practitioners working with the HE sector in the North East of England, we evaluate the progression of sector c... [more]

The exploitation of solar energy, an unlimited and renewable energy resource, is of prime interest to support the replacement of fossil fuels by renewable energy alternatives. Solar energy can be used via concentrated solar power (CSP) combined with thermochemical energy storage (TCES) for the conversion and storage of concentrated solar energy via reversible solid−gas reactions, thus enabling round the clock operation and continuous production. Research is on-going on efficient and economically attractive TCES systems at high temperatures with long-term durability and performance stability. Indeed, the cycling stability with reduced or no loss in capacity over many cycles of heat charge and discharge of the material is pursued. The main thermochemical systems currently investigated are encompassing metal oxide redox pairs (MOx/MOx−1), non-stoichiometric perovskites (ABO3/ABO3−δ), alkaline earth metal carbonates and hydroxides (MCO3/MO, M(OH)2/MO with M = Ca, Sr, Ba). The metal oxides/... [more]

Electric vehicles represent a necessary alternative for wheeled transportation to meet the global and national targets specified in the Paris Agreement of 2016. However, the high concentration of electric vehicles exposes their harmful effects on the power grid. This reflects negatively on electricity market prices, making the charging of electric vehicles less cost-effective. This study investigates the economic potential of different charging strategies for an existing office site in Austria with multiple charging infrastructures. For this purpose, a proper mathematical representation of the investigated case study is needed in order to define multiple optimization problems that are able to determine the financial potential of different charging strategies. This paper presents a method to implement electric vehicles and stationary battery storage in optimization problems with the exclusive use of linear relationships and applies it to a real-life use case with measured data to prove... [more]

In a bid to respond to the challenges being faced in the installation of flywheel-based electric energy storage systems (EESSs) in customer-side facilities, namely high safety, high energy/power densities and low cost, research work towards the development of a novel, one-body, laminated-rotor flywheel, based on a switched reluctance machine (OBOLAR-Fly SR machine) is presented, where the laminated rotor provides both the energy storage and motor/generator functions. The one-body architecture improves compactness and robustness. Besides, the rotor’s laminated body ensures inherently high safety. From the design perspective, the rotor’s dual purpose causes the traditional electrical machines design aspects, such as power development, cooling, losses, torque ripple, etc., to clash with the typical requirements of a flywheel, namely in-vacuum operation and moment of inertia. This results in six main trade-offs to be addressed during the design process: rotor material, speed ratio, number... [more]

In this research, automatic fouling cleaning systems that clean and prevent the deposit of fouling by regularly circulating sponge or ceramic balls are proposed. Characteristics of the finned and twisted inner tubes of the double pipe heat exchanger for the heat pump unit are also compared. Lastly, the 50RT-scale field test of the automatic fouling cleaning system integrated with the heat pump system was conducted by targeting temperature control of fish farms. The finned inner tube types presented a higher heat transfer rate than that of the twisted inner tube types. For the finned tube types, the refrigerant supply from the tangential direction was more advantageous due to the uniform distribution of refrigerant into 16 channels. The twisted tubes showed a higher water pressure drop than the finned inner tubes. An obvious increase in the fouling factor according to the operating hours was observed; however, it could be successfully decreased by operating the fouling cleaning system f... [more]

As a component of China’s strategic emerging industries, green lighting is an important industry supporting the high-quality and high-efficiency development of China’s economy, and is also an important way to achieve energy conservation and emission reduction. At present, China has basically established a policy framework to promote the development of green lighting industry, but there is no empirical evidence on the performance of existing policies on energy conservation and emission reduction. Based on the development status of China’s green lighting industry, this paper sorts out the milestones of China’s green lighting industry policy and the current status of the framework of the existing green lighting industry development policies, constructs a policy performance evaluation model for China’s green lighting industry based on the difference-in-difference (DID) model, and evaluates the implementation effects of green lighting industry policies in China from the perspective of energ... [more]

The creation of efficient and compact heat exchangers is one of the priority tasks arising during the design of heat and gas supply to industrial and residential buildings. As a rule, finned surfaces and turbulization of heat carrier flows are used to increase the efficiency of heat exchange in heat exchangers. The present paper proposes to use novel materials, namely porous material, in the design of highly efficient heat exchangers. The investigation was carried out experimentally and theoretically. To study the possibility of creating such heat exchangers, a multi-purpose test bench is created. The aim of the study was to assess the intensity of heat transfer in heat exchangers using porous metal. Laboratory tests are carried out as part of the experimental study. In the theoretical study, the classical equation for the change in the heat flux density when the coolant passes through the porous insert was used. As a result, a mathematical model was obtained in the form of a second-or... [more]

Smartness and agility are two quality measures that are pragmatic to achieve a flexible, maintainable, and adaptable system in any business. The automotive industry also requires an enhanced performance matrix and refinement in the development strategies for manufacturing. The current development models used in automotive manufacturing are not optimal enough; thus, the overall expenditure is not properly managed. Therefore, it is essential to come up with flexible, agile techniques incorporating traceability methods. It overcomes the traditional manufacturing approaches that are usually inflexible, costly, and lack timely customer feedback. The article focuses on significant Requirements Management (RM) activities, including traceability mechanism, smart manufacturing process, and performance evaluation of the proposed methods in the automotive domain. We propose a manufacturing framework that follows smart agile principles along with proper traceability management. Our proposed approa... [more]