This work analyzes the possibility of a provision of force-majeure mode of the combat vehicles with the aid of disk construction installed in the baffler, the base of the operation of which is the method of residual cyclical quadratic chain code of construction of the “windows” of the movable disk. To determine the optimal parameters of the moving disk of the rotor system, mathematical modeling was performed. The results of mathematical modeling were used to create a PC-based calculation program. The calculation was performed for the rotational frequency ω = 300 s−1 andfor harmonic numbers from 1 to 100. The waveforms used in simulation were as follows: quasi-trapezoidal and rectangular. It is established that at the number of “windows” m = 276 in the moving disk of the rotor system the radiation spectrum acquires a uniform distribution. The object of the research is the process of extreme burning of fuel material in the combat vehicles’ engines, ensuring, according to the technical po... [more]

A good thermal environment is important in a place where occupants stay for a long time. Since heating a house consumes a lot of energy, an energy-efficient heating method will be required. Then, by combining a heat pump and underfloor heating, there is a possibility that both thermal comfort and energy saving can be achieved. The survey was conducted on a detached house located in Nagano Prefecture, Japan. The average outside air temperature was 4.2 °C. This study investigated the indoor thermal environment, evaluated the operating performance of the heat pump, and calculated the heat load by two-dimensional analysis. More than 80% of the subjects were satisfied with the thermal environment and the neutral temperature was 18.9 °C. In the operation of the heat pump, defrost operation was confirmed, but the average COP was 2.9, and it operated efficiently. In addition, the heat loss from the foundation slab was examined. Proper insulation placement has shown the potential to reduce heat... [more]

Indonesia has an increasing electricity demand that is mostly met with fossil fuels. Although Indonesia plans to ramp up Renewable Energy Technologies (RET), implementation has been slow. This is unfortunate, as the RET potential in Indonesia might be higher than currently assumed given the archipelago’s size. However, there is no literature overview of RET potentials in Indonesia and to what extent they can meet current and future electricity demand coverage. This paper reviews contemporary literature on the potential of nine RET in Indonesia and analyses their impact in terms of area and demand coverage. The study concludes that Indonesia hosts massive amounts of renewable energy resources on both land and sea. The potentials in the academic and industrial literature tend to be considerably larger than the ones from the Indonesian Energy Ministry on which current energy policies are based. Moreover, these potentials could enable a 100% renewables electricity system and meet future de... [more]

This paper investigates the suitability of the community cooperatives (CC) model for the implementation of renewable energy communities (REC), as prescribed by art. 22 of EU Directive 2018/2001, and temporarily transposed into the Italian law by art. 42-bis of the Law Decree n. 162/2019. The hypothesis explored analyses the potential synergies between RECs and CC, based on their similarities. In particular, the article takes into consideration: the actors involved in both the RECs and the CCs; the geographical scope in which they develop, and the purposes that these two legal forms intended to achieve. Through a literature review and the analysis of EU, national and regional legislations, the paper aims at (1) clarifying the main features of RECs and the CCs in Italy; (2) exploring the main differences between CCs and the other legal forms of cooperative (e.g., mutual cooperative, cooperative benefit, etc.) and assessing the extent to which CCs are more suitable to implement renewable... [more]

Bioenergy with carbon capture and storage (BECCS) can sequester atmospheric CO2, while producing electricity. The CO2 avoidance cost (CAC) is used to calculate the marginal cost of avoided CO2 emissions for BECCS as compared to other established energy technologies. A comparative analysis using four different reference-case power plants for CAC calculations is performed here to evaluate the CO2 avoidance cost of BECCS implementation. Results from this work demonstrate that BECCS can generate electricity at costs competitive with other neutral emissions technologies, while simultaneously removing CO2 from the atmosphere. Approximately 73% of current coal power plants are approaching retirement by the year 2035 in the U.S. After considering CO2 sequestered from the atmosphere and coal power plant CO2 emissions displaced by BECCS, CO2 emissions can be reduced by 1.4 billion tonnes per year in the U.S. alone at a cost of $88 to $116 per tonne of CO2 removed from the atmosphere, for 10% to... [more]

Often, second law-based studies present merely entropy calculations without demonstrating how and whether such calculations may be beneficial. Entropy generation is commonly viewed as lost work or sometimes a source of thermodynamic losses. Recent literature reveals that minimizing the irreversibility of a heat engine may correspond to maximizing thermal efficiency subject to certain design constraints. The objective of this article is to show how entropy calculations need to be interpreted in thermal processes, specifically, where heat-to-work conversion is not a primary goal. We will study four exemplary energy conversion processes: (1) a biomass torrefaction process where torrefied solid fuel is produced by first drying and then torrefying raw feedstock, (2) a cryogenic air separation system that splits ambient air into oxygen and nitrogen while consuming electrical energy, (3) a cogeneration process whose desirable outcome is to produce both electrical and thermal energy, and (4) a... [more]

Heat enhancement and heat removal remain important topics in engineering. Furthermore, flow in a laminar regime can reduce the cost of cooling. In the present study, flow in mini channels in a rectangular cavity is investigated with water as a circulating fluid. The height of the channel in the cavity is varied and interaction of the free flow above the channel with flow through the channel has been investigated. It is shown that a combination of these two flows can provide the optimum heat removal at a Reynolds number of 750. This finding is valid if one ignores the friction effect to the wall. The best configuration is for an aspect ratio AR = 6. If the pressure drop is taken into consideration, then the performance evaluation criterion shows that the mini-channel with aspect ratio AR = 12 is the best configuration. Different correlations have been obtained between the Nusselt number, pressure drop, friction factor, performance evaluation criterion, and the Reynolds number and the he... [more]

In this paper, the energy performance of a university campus in a tropical climate is assessed, and four mixed classroom buildings are compared using benchmarking methods based on simple normalization: the classic Energy Use Intensity (EUI), end-used based EUI, and people-based EUI. To estimate the energy consumption of the case studies, building energy simulations were carried out in EnergyPlus using custom inputs. The analysis found that buildings with more classroom spaces presented higher energy consumption for cooling and lighting than others. In comparison, buildings with a greater percentage of laboratories and offices exhibited higher energy consumption for plug loads. Nevertheless, differences were identified when using the people-based EUI since buildings with larger floor areas showed the highest values, highlighting the impact of occupant behavior on energy consumption. Given the fact that little is known about a benchmark range for university campuses and academic building... [more]

The Stirling engine is an alternative solution to produce cleaner energy in order to achieve the reduction of the fossil fuel consumption and the CO2 emissions. It comprises an external combustion engine that can convert any external heat source into mechanical power, through cyclic expansion and compression of a working gas in a closed-regenerative cycle, with or without driving mechanisms. The free-piston Stirling Engine is significantly preferred because of the absence of any mechanical linkage resulting in longer operating life, lower noise pollution, maintenance and vibration free, self-starting and high thermal efficiency. The aim of this paper is to summarize the research works on the free-piston Stirling engine technologies and models. First, the working principles of the free-piston Stirling engine are described, identifying different configurations. Then, several applications are presented. Finally, a detailed review of the models available in literature is given, pointing ou... [more]

This study examines various low voltage levels applied to a direct current residential nanogrid (DC-RNG) with respect to the efficiency and component cost of the system. Due to the significant increase in DC-compatible loads, on-site Photovoltaic (PV) generation, and local battery storage, DC distribution has gained considerable attention in buildings. To provide an accurate evaluation of the DC-RNG’s efficiency and component cost, a one-year load profile of a conventional AC-powered house is considered, and AC appliances’ load profiles are scaled to their equivalent available DC appliances. Based on the modified load profiles, proper wiring schemes, converters, and protection devices are chosen to construct a DC-RNG. The constructed DC-RNG is modeled in MATLAB software and simulations are completed to evaluate the efficiency of each LVDC level. Four LVDC levels—24 V, 48 V, 60 V, and 120 V—are chosen to evaluate the DC-RNG’s efficiency and component cost. Additionally, impacts of addin... [more]

In most DC power systems, power electronic devices can introduce ripple content into the DC grid, where large input ripple currents on the DC link can have a negative influence. Under these circumstances, DC side filters play an important role in the reduction of ripple content. In this paper, based on a full detailed closed loop model of the entire offshore wind farm multi-terminal DC network, the effect of filter capacitors connected at different sections of the system on the limitation of the AC ripple content, particularly in the DC cables, is studied. In contrast to other work on HVDC for offshore wind, where simplified or equivalent circuits are mainly used while concentrating on the power and control system, this study can be regarded as the specific study of filter capacitors operating within a detailed system model. Utilising the advantages of PLECS, which is a highly effective tool in the simulation of power electronic circuits, no small-signal or simplified equivalent models... [more]

A novel maximum power point tracking (MPPT) technique based on mutual coordination of two photovoltaic (PV) modules/arrays has been proposed for distributed PV (DPV) systems. The proposed technique works in two stages. Under non-mismatch conditions between PV modules/arrays, superior performance stage 1 is active, which rectifies the issues inherited by the perturb and observe (P&O) MPPT. In this stage, the technique revolves around the perturb and observe (P&O) algorithm containing an intelligent mechanism of leader and follower between two arrays. In shading conditions, stage 2 is on, and it works like conventional P&O. Graphical analysis of the proposed technique has been presented under different weather conditions. Simulations of different algorithms have been performed in Matlab/Simulink. Simulation results of the proposed technique compliment the graphical analysis and show a superior performance and a fast response as compared to others, thus increasing the efficiency of distri... [more]

The demand for energy has rapidly grown around the world. Solar floating photovoltaic (FPV) systems are an efficient solution to solve the issues from nonrenewable energy sources, such as reduction of CO2 emission, limitation of global warming, environmentally friendly, a great innovation in sustainable aquaculture, and a new ecofriendly technique, along with reducing production costs, especially regarding the scarcity of habitable land. A large number of installation projects using FPV technology have been operated in water bodies such as lakes and dams/reservoirs. However, deployment of FPV offshore is still limited because of the existing characteristics of marine/sea environments that are different from onshore, such as wind loads and wave loads. Despite these difficulties, there are several projects that have been installed in some countries and gained many significant achievements. It opened possibilities to apply FPV systems offshore worldwide. In this review, we present a brief... [more]

In this work, three-dimensional thermal simulations of single 18650 lithium-ion battery cell and 75 V lithium-ion battery pack composed of 21 18650 battery cells are performed based on a multi-scale multi-domain (MSMD) battery modeling approach. Different cooling approaches’ effects on 18650 lithium-ion battery and battery pack thermal management under fast discharging and external shorting conditions are investigated and compared. It is found that for the natural convection, forced air cooling, and/or mini-channel liquid cooling approaches, the temperature of battery cell easily exceeds 40 °C under 3C rate discharging condition. While under external shorting condition, the temperature of cell rises sharply and reaches the 80 °C in a short period of time, which can trigger thermal runaway and may even lead to catastrophic battery fire. On the other hand, when the cooling method is single-phase direct cooling with FC-72 as coolant or two-phase immersed cooling by HFE-7000, the cell temp... [more]

This article presents comparative results on the energy performance of buildings in the Mediterranean. Many buildings in the Mediterranean exhibit low energy performance ranking. Thermochromic windows are able to improve the energy consumption by controlling the gains from sunlight. In this article, reference buildings in 15 cities around the Mediterranean are investigated. In this work, a dynamic building information modeling approach is utilized, relying on three-dimensional geometry of office buildings. Calculations of the energy demand based on computational simulations of each location were performed, for the estimation of heating and cooling loads. The presented study highlighted the need for high-resolution data for detailed simulation of thermochromic windows in buildings of Mediterranean cities. Temperature is one of the main climate parameters that affect the energy demand of buildings. However, the climate of Mediterranean cities nearby the sea may affect the energy demand.... [more]

The introduction of a complex electrical vehicle charging (EVC) infrastructure consisting of an electrical vehicle (EV) charger and renewable energy source (RES) in the distribution system has been required as an important countermeasure for global environmental issues. However, the problems for hosting capacity and power stability of the distribution feeder can be caused by the penetration of lager scaled RES and EVC infrastructure. Further, it is required for the efficient operation method to prevent congestion and to ensure hosting capacity for the distribution feeder due to the increase of variable RES and EVC infrastructure in the distribution systems. In order to solve these problems, it is necessary to develop a technology which is capable of stably introducing an EVC infrastructure without reinforcing the existing distribution system. Therefore, to maintain the existing hosting capacity of distribution feeder and allowable limits, this paper presents a virtual power line (VPL)... [more]

With regard to safety, efficiency and lifetime of battery systems, the thermal behavior of battery cells is of great interest. The use of models describing the thermoelectric behavior of battery cells improves the understanding of heat generation mechanisms and enables the development of optimized thermal management systems. In this work, a novel experimental approach is presented to determine both the irreversible heat due to ohmic losses and the reversible heat due to entropy changes directly via heat flow measurements. No additional information about thermal properties of the battery cell, such as heat capacity or thermal conductivity, are required. Thus, the exothermic and endothermic nature of reversible heat generated in a complete charge/discharge cycle can be investigated. Moreover, the results of the proposed method can potentially be used to provide an additional constraint during the identification process of the equivalent circuit model parameters. The described method is a... [more]

Twin-screw compressors are widely used in aerodynamics, refrigeration and other fields. The screw rotors are the core component of the screw compressor and affect the performance of the compressor. This paper focuses on variable-lead rotors. A thermal process simulation model considering leakage is established to calculate the efficiency of the compressor. Different lead change methods are compared by evaluating the contact line, exhaust port and simulation results. The results show that the compressor obtains better performance when the lead decreases rapidly on the discharge side. Furthermore, the effects of the wrap angle and internal volume ratio on variable-lead rotors are studied. The work provides a reference for the design of the screw compressor rotor.

This article introduces an application of the recently developed hunger games search (HGS) optimization algorithm. The HGS is combined with chaotic maps to propose a new Chaotic Hunger Games search (CHGS). It is applied to solve the optimal power flow (OPF) problem. The OPF is solved to minimize the generation costs while satisfying the systems’ constraints. Moreover, the article presents optimal siting for mixed renewable energy sources, photovoltaics, and wind farms. Furthermore, the effect of adding renewable energy sources on the overall generation costs value is investigated. The exploration field of the optimization problem is the active output power of each generator in each studied system. The CHGS also obtains the best candidate design variables, which corresponds to the minimum possible cost function value. The robustness of the introduced CHGS algorithm is verified by performing the simulation 20 independent times for two standard IEEE systems—IEEE 57-bus and 118-bus systems... [more]

Carbon capture, utilization, and storage (CCUS) is an attractive technology for the decarbonization of global energy systems. However, its early development stage makes impact assessment difficult. Moreover, rising popularity in carbon pricing necessitates the development of a methodology for deriving carbon abatement costs that are harmonized with the price of carbon. We develop, using a combined bottom-up analysis and top-down learning curve approach, a levelized cost of carbon abatement (LCCA) model for assessing the true cost of emissions mitigation in CCUS technology under carbon pricing mechanisms. We demonstrate our methodology by adapting three policy scenarios in Canada to explore how the implementation of CO2-to-diesel technologies could economically decarbonize Canada’s transportation sector. With continued policy development, Canada can avoid 932 MtCO2eq by 2075 at an LCCA of CA$209/tCO2eq. Technological learning, low emission hydroelectricity generation, and cost-effective... [more]

Solid-state plastic crystal electrolytes (SPCEs) have attracted much attention due to their high ionic conductivity at room temperature and polymer-like plasticity. Herein, we made a LiFePO4||Li solid state battery based on SPCEs. A SPCE film is made up of glass fiber, succinonitrile (SN), lithium bis (triflu-romethanesulphonyl) imid (LiTFSI), and LiNO3. Glass fiber is introduced to improve the mechanical property, and LiNO3 served as an additive to stabilize electrolyte/Li interface. The SPCE film delivers a high ionic conductivity of 7.3 × 10−4 S cm−1 at room temperature and has excellent stability with Li-metal anode. SPCE is also infused into cathode electrode and used as the interface with cathode particles, which can access a large interface contact area and deform reversibly with volume change. The LiFePO4||Li solid state battery based on SPCE can work well at ambient temperature, which shows a high initial specific capacity of 121.4 mAh g−1 and has 86.9% retention after 90 cycl... [more]

The increasing use of lithium batteries and the necessary integration of battery management systems (BMS) has led international standards to demand functional safety in electromobility applications, with a special focus on electric vehicles. This work covers the complete design of an enhanced automotive BMS with functional safety from the concept phase to verification activities. Firstly, a detailed analysis of the intrinsic hazards of lithium-based batteries is performed. Secondly, a hazard and risk assessment of an automotive lithium-based battery is carried out to address the specific risks deriving from the automotive application and the safety goals to be fulfilled to keep it under control. Safety goals lead to the technical safety requirements for the next hardware design and prototyping of a BMS Slave. Finally, the failure rate of the BMS Slave is assessed to verify the compliance of the developed enhanced BMS Slave with the functional safety Automotive Safety Integrity Level (A... [more]

As more countries seek solutions to their de-carbonization targets using renewable energy (RE) technologies, interconnection standards and national grid codes for distributed energy resources (DER) are being updated to support higher penetrations of RE and improve grid stability. Common grid-code revisions mandate DER devices, such as solar inverters and energy storage systems, ride-through (RT) voltage and frequency disturbances. This is necessary because as the percentage of generation from DER increases, there is a greater risk power system faults will cause many or all DER to trip, triggering a substantial load-generation imbalance and possible cascading blackout. This paper demonstrates for the first time a methodology to verify commercial DER devices are compliant to new voltage, frequency, and rate of change of frequency (ROCOF) RT requirements established in IEEE Std. 1547-2018. The methodology incorporates a software automation tool, called the SunSpec System Validation Platfo... [more]

Making full use of wind energy can effectively alleviate the global energy shortage and environment contamination problems. Nevertheless, how to significantly improve the performance of the wind turbine airfoil and blade is a crucial issue. As the novel flow control method, the co-flow jet (CFJ) technology is one of the most potential methods to solve this problem. Thus, the effects of the CFJ technology on the performance enhancement of the S809 airfoil and Phase VI wind turbine blade are explored in this study. Furthermore, the effects of the injection location and jet momentum coefficient are studied, and an adaptive jet momentum coefficient strategy of the CFJ technology is proposed. Results demonstrate that the CFJ technology can significantly improve the maximum lift coefficient and maximum corrected lift-to-drag ratio of the S809 airfoil. Moreover, the power coefficient of the Phase VI wind turbine blade at the low tip speed ratio is greatly enhanced as well. In particular, the... [more]

The rapid growth of aquaculture production has required a huge power demand, which is estimated to be about 40% of the total energy cost. However, it is possible to reduce this expense using alternatives such as renewable energy (i.e., solar energy) instead of non-renewable energy. Solar energy is one of the cleanest energy sources and is touted as a potential renewable energy source for the world with benefits such as reducing CO2 emissions, reversing global warming by being eco-friendly, and bringing innovation to sustainable aquaculture and potential cost-efficiency for manufacturing. In this review, we present an overview of using non-renewable and renewable energy sources for aquaculture by reviewing several articles and applications of solar energy at many companies in the world. Moreover, this review shows potential and future trends using solar energy for aquaculture.