The article presents the results of a study aiming to select the optimal source of heat for a newly designed single-family home. Commercial software was used to compare heating and ventilation systems involving a bituminous coal boiler, a condensing gas boiler, a biomass boiler, a heat pump with water and glycol as heat transfer media. The effectiveness of natural ventilation, mechanical ventilation with a ground-coupled heat exchanger, and solar heater panels for water heating were evaluated. The analysis was based on the annual demand for useful energy, final energy, and non-renewable primary energy in view of the pollution output of the evaluated heating systems. The analysis revealed that the heat pump with water and glycol was the optimal solution. However, the performance of the heat pump in real-life conditions was below its maximum theoretical efficiency. The biomass boiler contributed to the highest reduction in pollutant emissions (according to Intergovernmental Panel on Clim... [more]

The dynamic features of microgrid operation, such as on-grid/off-grid operation mode, the intermittency of distributed generators, and its dynamic topology due to its ability to reconfigure itself, cause misfiring of conventional protection schemes. To solve this issue, adaptive protection schemes that use robust communication systems have been proposed for the protection of microgrids. However, the cost of this solution is significantly high. This paper presented an intelligent fault detection (FD) system for microgrids on the basis of local measurements and machine learning (ML) techniques. This proposed FD system provided a smart level to intelligent electronic devices (IED) installed on the microgrid through the integration of ML models. This allowed each IED to autonomously determine if a fault occurred on the microgrid, eliminating the requirement of robust communication infrastructure between IEDs for microgrid protection. Additionally, the proposed system presented a methodolog... [more]

The bioeconomy is the cornerstone of the EU’s policy for shifting economic and societal trends towards circularity and low carbon arrangements. Europe has several crops that can be used as raw materials for this purpose, however pressure on land which might displace other activities and industrial competition for cost efficient raw materials remains a challenge. Hence, ensuring good yielding capacity and examining the likelihood to produce more by exploiting low quality, unused land can present significant opportunities to increase sustainable, locally sourced supply and at the same time offer profitable solutions to both industry and the farmers. This paper estimates the production costs of fourteen crops (oil, sugar, starch and lignocellulosic) and analyses how their profitability can be influenced by yield increases and cultivation in low quality land. Results show that there are profitable options for all crops under current market prices and land types except for cases in countrie... [more]

This study has statistically analyzed the effect of boiler type and model year on CH4 emission factors, focusing on liquefied natural gas (LNG)—the most commonly used fuel in South Korean manufacturing combustion facilities. Samples were collected from the boilers of 39 manufacturing combustion facilities that use LNG fuel. The CH4 emission factors were developed based on 4 overhead fire-tube boilers, 14 once-through boilers, 14 vertical boilers with vertical water tubes, and 7 other boilers. This resulted in an average value of 0.11 CH4 kg/TJ, which is considerably lower than the Intergovernmental Panel on Climate Change (IPCC) 1996 guidelines(G/L) emission factor of 5 CH4 kg/TJ currently used in South Korea. In the Kruskal−Wallis test results, the significance probability was greater than 0.05 for the boiler types and ages, and there was no major difference in the average distributions, according to the boiler type or age. Therefore, according to the results of this study, the differ... [more]

With the rapid development of ultra-high-voltage (UHV) AC/DC, especially the step-by-step upgrading of the UHV DC transmission scale, security presents new challenges. Commutation failure (CF) is a common fault in line commutated converter (LCC) high-voltage direct current (HVDC) power systems. Once failure happens, it may cause power oscillations in a system. In this paper, taking a two-area AC/DC parallel interconnected power system as the example, based on the impulse response model of second-order linear system, the mechanism of power oscillation on the AC tie-line caused by CF are clarified. It is proved that the peak value of the AC tie-line power oscillation is mainly determined by the DC power and the equivalent CF duration, the frequency and damping ratio of dominant area oscillation mode. Meanwhile, the peak time is mainly determined by the oscillation frequency. Finally, the correctness and effectiveness of the algorithms are verified by a simulation analysis of an extended... [more]

Widely used distribution generations (DGs) and energy storage systems (ESSs) enable a distribution system to have a more flexible fault reconfiguration capability. In order to enhance the service reliability and the benefit of distribution networks with DGs and ESSs, this paper proposes a novel distribution system reconfiguration (DSR) model including DGs and ESSs. Meanwhile, the impact of sectionalizing switches and tie switches on reliability is considered. The concept of “boundary switch” is introduced for quantifying the customer interruption duration. The DSR model is presented to minimize the sum of the customer interruption cost, the operation cost of switches, and the depreciation cost of DGs and ESSs. Furthermore, the proposed model is converted into a mixed-integer linear programming, which can be efficiently solved by commercial solvers. Finally, the validity and efficiency of the proposed DSR model are verified by a modified IEEE 33-bus system and a modified PG&E69-bus netw... [more]

The flow control over the blades of a small horizontal-axis wind turbine (HAWT) model using a dielectric barrier discharge plasma actuator (DBD-PA) was studied based on large-eddy simulations. The numerical simulations were performed with a high-resolution computational method, and the effects of the DBD-PA on the flow fields around the blades were modeled as a spatial body force distribution. The DBD-PA was installed at the leading edge of the blades, and its impacts on the flow fields and axial torque generation were discussed. The increase in the ratios of the computed, cycle-averaged axial torque reasonably agreed with that of the available experimental data. In addition, the computed results presented a maximum of 19% increase in the cycle-averaged axial torque generation by modulating the operating parameters of the DBD-PA because of the suppression of the leading edge separation when the blade’s effective angles of attack were relatively high. Thus, the suppression of the leadin... [more]

The acoustic performance of floors plays a primary role in the total quality rating of a residential building. The sound insulation of lightweight frame floors, which are increasingly being used in housing, depends on a number of factors and technical details. In effect, the sound transmission scheme is distinctly more complicated than in the case of homogeneous massive partitions. The aim of the study was to develop effective insulating layers of lightweight floors intended for use in residential buildings. The floor system should satisfy legal requirements in terms of airborne and impact sound insulation. The research was based on laboratory measurements taken in a standard test facility. Ten different models of wood and metal floors were considered. The acoustic performance of their basic structure was insufficient; however, the application of effective floating floors and suspended ceilings improved it greatly and succeeded in potential meeting requirements and satisfying most inha... [more]

Permanent magnet synchronous motors (PMSMs) have commonly been used in a wide spectrum ranging from industry to home appliances because of their advantages over their conventional counterparts. However, PMSMs are multiple-input multiple-output (MIMO) systems with nonlinear dynamics, which makes their control relatively difficult. In this study, a novel model predictive control mechanism, which is referred to as the Runge-Kutta model predictive control (RKMPC), has been applied for speed control of a commercial permanent magnet synchronous motor. Furthermore, the RKMPC method has been utilized for the adaptation of the speed of the motor under load variations via RKMPC-based online parameter estimation. The superiority of RKMPC is that it can take the constraints on the inputs and outputs of the system into consideration, thereby handling the speed and current control in a single loop. It has been shown in the study that the RKMPC mechanism can also estimate the load changes and unknown... [more]

Reliability assessment in traditional power distribution systems has played a key role in power system planning, design, and operation. Recently, new information and communication technologies have been introduced in power systems automation and asset management, making the distribution network even more complex. In order to achieve efficient energy management, the distribution grid has to adopt a new configuration and operational conditions that are changing the paradigm of the actual electrical system. Therefore, the emergence of the cyber-physical systems concept to face future energetic needs requires alternative approaches for evaluating the reliability of modern distribution systems, especially in the smart grids environment. In this paper, a reliability approach that makes use of failure modes of power and cyber network main components is proposed to evaluate risk analysis in smart electrical distribution systems. We introduce the application of Failure Modes and Effects Analysi... [more]

This paper aims at investigating the production of high quality briquettes from olive mill solid waste (OMSW) mixed with corn starch as a binder for energy production. For this purpose, different mass percentages of OMSW and binder were considered; 100%-0%, 90%-10%, 85%-15%, and 70%-30%, respectively. The briquetting process of the raw mixtures was carried out based on high pressures. Physico-chemical and mechanical characterizations were performed in order to select the best conditions for the briquettes production. It was observed that during the densification process, the optimal applied pressure increases notably the unit density, the bulk density, and the compressive strength. Mechanical characterization shows that the prepared sample with 15% of corn starch shows the best mechanical properties. Moreover, the corn starch binder affects quietly the high heating value (HHV) which increases from 16.36 MJ/Kg for the 100%-0% sample to 16.92 MJ/Kg for the 85%-15% sample. In addition, th... [more]

Swap charging (SC) technology offers the possibility of swapping the batteries of electric vehicles (EVs), providing a perfect solution for achieving a long-distance freeway trip. Based on SC technology, a shared SC system (SSCS) concept is proposed to overcome the difficulties in optimal swap battery strategies for a large number of EVs with charging requests and to consider the variance in the battery charging rate simultaneously. To realize the optimal SSCS design, a binary integer programming model is developed to balance the tradeoff between the detour travel cost and the total battery recharge cost in the SSCS. The proposed method is verified with a numerical example of the freeway system in Guangdong Province, China, and can obtain an exact solution using off-the-shelf commercial solvers (e.g., Gurobi).

Decomposing main drivers of CO2 emissions and predicting the trend of it are the key to promoting low-carbon development for coping with climate change based on controlling GHG emissions. Here, we decomposed six drivers of CO2 emissions in Changxing County using the Logarithmic Mean Divisia Index (LMDI) method. We then constructed a model for CO2 emissions prediction based on a revised version of the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model and used it to simulate energy-related CO2 emissions in five scenarios. Results show that: (1) From 2010 to 2017, the economic output effect was a significant, direct, dominant, and long-term driver of increasing CO2 emissions; (2) The STIRPAT model predicted that energy structure will be the decisive factor restricting total CO2 emissions from 2018 to 2035; (3) Low-carbon development in the electric power sector is the best strategy for Changxing to achieve low-carbon development. Under the tested sc... [more]

Electric buses are increasingly appearing on the streets of cities around the world. Thus, it is necessary to consider the impact of their charging on the distribution system operation, especially near the charging point. This article presents the problems that may arise while new charging points are connected. Research was carried out on the existing charging point at Spartańska Street in Warsaw, which allowed to obtain daily bus charging profiles and voltage curves. The authors then proposed an exemplary model of a bus terminus with the designed infrastructure for charging buses, based on the assumptions of the public transport operator in Warsaw. The comparison of these two solutions was made and based on it, a methodology of calculating daily demand for any terminus was prepared. In addition, no problems with the power quality were found during the research. This allows us to state that the introduction of electric buses into the fleet of passenger carriers will have a minor impact... [more]

In 20th century, many countries have liberalized their electricity market. This power markets liberalization has directed generation companies as well as wholesale buyers to undertake a greater intense risk exposure compared to the old centralized framework. In this framework, electricity price prediction has become crucial for any market player in their decision-making process as well as strategic planning. In this study, a prototype asymmetric-based neuro-fuzzy network (AGFINN) architecture has been implemented for short-term electricity prices forecasting for ISO New England market. AGFINN framework has been designed through two different defuzzification schemes. Fuzzy clustering has been explored as an initial step for defining the fuzzy rules while an asymmetric Gaussian membership function has been utilized in the fuzzification part of the model. Results related to the minimum and maximum electricity prices for ISO New England, emphasize the superiority of the proposed model over... [more]

The reliability analysis method and risk assessment model for the traditional single network no longer meet the requirements of the risk analysis of coupled systems. This paper establishes a risk assessment system of electric-gas integrated energy system (EGIES) considering the risk security of components. According to the mathematical model of each component, the EGIES steady state analysis model considering the operation constraints is established to analyze the operation status of each component. Then the EGIES component accident set is established to simulate the accident consequences caused by the failure of each component to EGIES. Furthermore, EGIES risk assessment system is constructed to identify the vulnerability of EGIES components. Finally, the risk assessment of IEEE14-NG15 system is carried out. The simulation results verify the effectiveness of the proposed method.

The energy storage inverter system has the characteristics of nonlinearity, strong coupling, variable parameters, and flexible mode switching between parallel and off grid. In order to improve the control performance of the grid-side inverter of the energy storage system, an improved Linear Active Disturbance Rejection Control (LADRC) based on proportional differentiation is proposed to replace the traditional LADRC in the voltage outer loop control. In this paper, the observation gain coefficient of the sum of the disturbances of the traditional Linear Extended State Observer (LESO) is improved to a proportional differentiation link, which effectively reduces the degree of the disturbance observation amplitude drop and the phase lag, and increases the observation bandwidth of LESO. Compared with traditional LADRC, it not only improves the observation accuracy of LESO for disturbance, but also improves the anti-interference performance of LADRC. Finally, the control effects of improved... [more]

Today, most countries in the world have mandatory regulations, more or less strict, regarding energy efficiency in buildings. However, a large percentage of the buildings already built were constructed under lax or non-existing regulations in this regard. Therefore, many countries are facing the energy refurbishment of their existing buildings to reduce their carbon footprint. Depending on ambient weather conditions where a building settles, its operation with respect to the achievement of maximum energy efficiency should usually be different. This happens in subtropical climates when, during the year and depending on the season, the building needs to conserve heat, evacuate it or even make an exchange with the outside to take advantage of favorable environmental conditions. This paper presents a complete methodology for conducting building energy efficiency refurbishments in subtropical climates in order to convert them into minimum energy buildings. The proposed methodology is illust... [more]

In this study, the effects of the jet fan speed, heat release rate and aspect ratio on smoke movement in tunnel fires have been investigated. The jet fan speed was changed from 6.25 (25%) to 12.5 m/s (50%), 18.75 m/s (75%), and 25 m/s (100%). The heat release rate was set up from 3.9 to 6 MW and 16 MW, the aspect ratio was changed from 0.6 to 1 and 1.5, respectively. The lower the jet fan speed is, the longer the smoke back-layering length is. With a higher velocity, the smoke tends to move out of the tunnel quickly; however, smoke stratification also occurs, and this reduces visibility. This could make it difficult for people to evacuate. With a higher heat release rate, the smoke tends to move far away from the fires quickly when compared with other cases. Additionally, the higher the heat release is, the longer the smoke back-layering is. Finally, with a higher aspect ratio, the smoke back layering length in the tunnel is also longer. The smoke layer thickness is also larger than in... [more]

This study dealt with evaluating the (J85-GE-5H) military turbojet engine (TJE) in terms of exergetic and advanced exergetic analyses at Military (MIL) and Afterburner (AB) process modes by utilizing kerosene (JP-8) and hydrogen (H2) fuels. First, exergy and advanced exergy analyses of the engine were performed using JP-8 fuel as per actual engine operating conditions. These analyses of the turbojet engine using hydrogen fuel were also examined parametrically. The performance evaluation of the engine was lastly executed by comparing the obtained results for both fuels. Based on the parametric studies undertaken, the entire engine’s exergetic efficiency with JP-8 was reckoned 30.85% at the MIL process mode while it was calculated as 16.98% at the AB process mode. With the usage of H2, the efficiencies of the engine decreased to 28.62% and 15.33% for the above mentioned two modes, respectively. As the supreme exergy destructions occurred in the combustion chamber (CC) and afterburner exh... [more]

Reliable transmission expansion planning is critical to power systems’ development. To make reliable and sustainable transmission expansion plans, numerous sources of uncertainty including demand, generation capacity, and fuel cost must be taken into consideration in both spatial and temporal dimensions. This paper presents a new approach to selecting a small number of high-quality scenarios for transmission expansion. The Kantorovich distance of social welfare distributions was used to assess the quality of the selected scenarios. A case study was conducted on a power system model that represents the U.S. Eastern and Western Interconnections, and ten high-quality scenarios out of a total of one million were selected for two transmission plans. Results suggested that scenarios selected using the proposed algorithm were able to provide a much more accurate estimation of the value of transmission plans than other scenario selection algorithms in the literature.

This research work presents a comparative thermal performance assessment of the laminar flow cooling blocks produced for automotive headlight assembly using a high power Light Emitting Diode (LED) chip. A three-dimensional numerical model with conjugate heat transfer in solid and fluid domains was used. Laminar flow was considered in the present analysis. The validation of the numerical model was realized by using the measured data from the test rig. It was observed that substantial temperature variations were occurred around the LED chip owing to volumetric heat generation. The cooling board with lower height performs better thermal performance but higher pressure drop for the same mass flow rates. The cooling board with the finned cover plate performs better thermal performance but results in an increased pressure drop for the same mass flow rates. Increasing the power of the LED results in higher temperature values for the same mass flow rates. The junction temperature is highly dep... [more]

Biogas upgrading is a key operation for transforming raw biogas into valuable biomethane that can be used as fuel or transported through pipelines. Pressure swing adsorption (PSA) is one possible technique that can be used for upgrading. ZSM-5 with high silica/aluminum (Si/Al) ratio has a reasonable CO2/CH4 selectivity and an almost linear CO2 adsorption isotherm, which can reduce power consumption. Extrusion of zeolites uses Al-based binders which can result in a denaturation and in a decrease of Si/Al ratio, promoting a steeper CO2 isotherm and also impacting the water adsorption. In this work, we have extruded a ZSM-5 (with a Si/Al = 200) using only silica-based binder. Different samples were obtained using different extrusion paste compositions and operating conditions and their textural properties characterized. The mechanical strength of the samples as well as the CO2, CH4, and H2O adsorption equilibrium isotherms at 303−343 K were measured. Our results show that it is possible t... [more]

Latent heat thermal energy storage (LHTES) using phase change materials (PCM) is one of the most promising ways for thermal energy storage (TES), especially in lightweight buildings. However, accurate control of the phase transition of PCM is not easy to predict. For example, neglecting the hysteresis or the effect of the speed of phase change processes reduces the accuracy of simulations of TES. In this paper, the authors propose a new software module for EnergyPlus™ that aims to simulate the hysteresis of PCMs during the phase change. The new module is tested by comparing simulation results with experimental tests done in a climatic chamber. A strong consistency between experimental and simulation results was obtained, while a discrepancy error of less than 1% was obtained. Moreover, in real conditions, as a result of quick temperature changes, only a partial phase transformation of the material is often observed. The new model also allows the consideration of the case with partial p... [more]

The pore-fractures network plays a key role in coalbed methane (CBM) accumulation and production, while the impacts of coal facies on the pore-fractures network performance are still poorly understood. In this work, the research on the pore-fracture occurrence of 38 collected coals from Sangjiang-Muling coal-bearing basins with multiple techniques, including mercury intrusion porosimetry (MIP), micro-organic quantitative analysis, and optic microscopy, and its variation controlling of coal face were studied. The MIP curves of 38 selected coals, indicating pore structures, were subdivided into three typical types, including type I of predominant micropores, type Ⅱ of predominant micropores and macropores with good connectivity, and type Ⅲ of predominant micropores and macropores with poor connectivity. For coal facies, three various coal facies were distinguished, including lake shore coastal wet forest swamp, the upper delta plain wet forest swamp, tidal flat wet forest swamp using Q-c... [more]