Open AccessArticle
Accuracy Enhancement of Mixed Power Flow Analysis Using a Modified DC Model
Energies 2016, 9(10), 776; doi:10.3390/en9100776 (registering DOI) -
Abstract
The mixed power flow analysis method decreases the computational complexity and achieves a high level of simulation accuracy. The mixed approach combines the ac with the dc power flow models, depending on the area of interest. The accurate ac model is used [...] Read more.
The mixed power flow analysis method decreases the computational complexity and achieves a high level of simulation accuracy. The mixed approach combines the ac with the dc power flow models, depending on the area of interest. The accurate ac model is used in the study area of interest to obtain high simulation accuracy, while the approximate dc model is used in the remainder of the system to reduce the required computations. In the original mixed approach, the errors originating from the use of the dc model may propagate to the area of interest where accurate simulation outcomes are required; thus, the simulation accuracy might not be satisfactory. This paper presents a new method of enhancing the simulation accuracy of the mixed power flow analysis using available information. In the proposed approach, a modified dc model is used instead of the traditional one and is constructed from an initial base-case ac solution. The new dc model compensates for the errors originating from the neglect of the real power losses and the assumption of a flat voltage magnitude in the conventional dc model. Thus, the proposed method can improve the simulation accuracy in the area of interest. The superior computational benefits can also be preserved by maintaining linear characteristics of the dc model. Case studies with the IEEE 118-bus system are provided to validate the enhanced accuracy of the proposed method. Full article
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Open AccessArticle
A Comparative Study of Novel Topologies of Magnetic Gears
Energies 2016, 9(10), 773; doi:10.3390/en9100773 (registering DOI) -
Abstract
The magnetic gear (MG) is an emerging technology that has been proved to possess superior performance over the conventional mechanical gear in many aspects. However, the existing markets of traditional mechanical gears have not yet been replaced by MGs. One of the [...] Read more.
The magnetic gear (MG) is an emerging technology that has been proved to possess superior performance over the conventional mechanical gear in many aspects. However, the existing markets of traditional mechanical gears have not yet been replaced by MGs. One of the major reasons is that MGs are susceptible to the permanent magnet (PM) materials, which are scarce and expensive, while mechanical counterparts are impervious to that. To solve such issues, the comparative studies of various designs of triple-layer PM-excited MGs are carried out to find out the optimal torque per unit PM volume design. The methodology of the Tabu algorithm is coupled with the finite element method (FEM) to search out the optimal solution of MGs. Full article
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Open AccessArticle
Design and Implementation of a High Efficiency, Low Component Voltage Stress, Single-Switch High Step-Up Voltage Converter for Vehicular Green Energy Systems
Energies 2016, 9(10), 772; doi:10.3390/en9100772 (registering DOI) -
Abstract
In this study, a novel, non-isolated, cascade-type, single-switch, high step-up DC/DC converter was developed for green energy systems. An integrated coupled inductor and voltage lift circuit were applied to simplify the converter structure and satisfy the requirements of high efficiency and high [...] Read more.
In this study, a novel, non-isolated, cascade-type, single-switch, high step-up DC/DC converter was developed for green energy systems. An integrated coupled inductor and voltage lift circuit were applied to simplify the converter structure and satisfy the requirements of high efficiency and high voltage gain ratios. In addition, the proposed structure is controllable with a single switch, which effectively reduces the circuit cost and simplifies the control circuit. With the leakage inductor energy recovery function and active voltage clamp characteristics being present, the circuit yields optimizable conversion efficiency and low component voltage stress. After the operating principles of the proposed structure and characteristics of a steady-state circuit were analyzed, a converter prototype with 450 W, 40 V of input voltage, 400 V of output voltage, and 95% operating efficiency was fabricated. The Renesas MCU RX62T was employed to control the circuits. Experimental results were analyzed to validate the feasibility and effectiveness of the proposed system. Full article
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Open AccessArticle
Evaluating the Management System Approach for Industrial Energy Efficiency Improvements
Energies 2016, 9(10), 774; doi:10.3390/en9100774 (registering DOI) -
Abstract
Voluntary environmental management systems (EMS) based on the international standard ISO 14001 have become widespread globally in recent years. The purpose of this study is to assess the impact of voluntary management systems on energy efficiency in the Swedish manufacturing industry by [...] Read more.
Voluntary environmental management systems (EMS) based on the international standard ISO 14001 have become widespread globally in recent years. The purpose of this study is to assess the impact of voluntary management systems on energy efficiency in the Swedish manufacturing industry by means of objective industrial energy data derived from mandatory annual environmental reports. The study focuses on changes in energy efficiency over a period of 12 years and includes both ISO 14001-certified companies and non-certified companies. Consideration is given to energy improvement efforts in the companies before the adoption of ISO 14001. The analysis has been carried out using statistical methods for two different industrial energy parameters: electricity and fossil fuel consumption. The results indicate that ISO 14001 adoption and certification has increased energy efficiency regarding the use of fossil fuel. In contrast, no effect of the management systems has been found concerning the use of electricity. The mixed results of this study are only partly in line with the results of previous studies based on perceptions of company representatives. Full article
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Open AccessArticle
On Optimal Cell Flashing for Reducing Delay and Saving Energy in Wireless Networks
Energies 2016, 9(10), 768; doi:10.3390/en9100768 -
Abstract
To save energy from cellular networks or to increase user-perceived performance, studying base station (BS) switching on–off is actively ongoing. However, many studies focus on the tradeoff between energy efficiency and user-perceived performance. In this paper, we propose a simple technique called [...] Read more.
To save energy from cellular networks or to increase user-perceived performance, studying base station (BS) switching on–off is actively ongoing. However, many studies focus on the tradeoff between energy efficiency and user-perceived performance. In this paper, we propose a simple technique called cell flashing. Cell flashing means that base stations are turned on and off periodically and rapidly so that, when one base station is turned on, the adjacent base stations which make interferences are always off. Thus, both energy efficiency and cell edge user performances can be improved. In general, switching off base stations to save energy can lead to longer file download time (or delay) to customers. Using flow-level dynamics, we analyze average delay and energy consumption of cellular networks when cell flashing is used. We show that both of total energy consumption and average flow-level delay decrease in the case of small cells. Extensive simulations confirm that cell flashing can significantly save the energy of the base stations, e.g., by up to 25% and, at the same time, reduce the average delay by up to 75%. Full article
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Open AccessArticle
Technical Evaluation of Superconducting Fault Current Limiters Used in a Micro-Grid by Considering the Fault Characteristics of Distributed Generation, Energy Storage and Power Loads
Energies 2016, 9(10), 769; doi:10.3390/en9100769 -
Abstract
Concerning the development of a micro-grid integrated with multiple intermittent renewable energy resources, one of the main issues is related to the improvement of its robustness against short-circuit faults. In a sense, the superconducting fault current limiter (SFCL) can be regarded as [...] Read more.
Concerning the development of a micro-grid integrated with multiple intermittent renewable energy resources, one of the main issues is related to the improvement of its robustness against short-circuit faults. In a sense, the superconducting fault current limiter (SFCL) can be regarded as a feasible approach to enhance the transient performance of a micro-grid under fault conditions. In this paper, the fault transient analysis of a micro-grid, including distributed generation, energy storage and power loads, is conducted, and regarding the application of one or more flux-coupling-type SFCLs in the micro-grid, an integrated technical evaluation method considering current-limiting performance, bus voltage stability and device cost is proposed. In order to assess the performance of the SFCLs and verify the effectiveness of the evaluation method, different fault cases of a 10-kV micro-grid with photovoltaic (PV), wind generator and energy storage are simulated in the MATLAB software. The results show that, the efficient use of the SFCLs for the micro-grid can contribute to reducing the fault current, improving the voltage sags and suppressing the frequency fluctuations. Moreover, there will be a compromise design to fully take advantage of the SFCL parameters, and thus, the transient performance of the micro-grid can be guaranteed. Full article
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Open AccessArticle
Feedback Linearization Controller for a Wind Energy Power System
Energies 2016, 9(10), 771; doi:10.3390/en9100771 -
Abstract
This paper deals with the control of a doubly-fed induction generator (DFIG)-based variable speed wind turbine power system. A system of eight ordinary differential equations is used to model the wind energy conversion system. The generator has a wound rotor type with [...] Read more.
This paper deals with the control of a doubly-fed induction generator (DFIG)-based variable speed wind turbine power system. A system of eight ordinary differential equations is used to model the wind energy conversion system. The generator has a wound rotor type with back-to-back three-phase power converter bridges between its rotor and the grid; it is modeled using the direct-quadrature rotating reference frame with aligned stator flux. An input-state feedback linearization controller is proposed for the wind energy power system. The controller guarantees that the states of the system track the desired states. Simulation results are presented to validate the proposed control scheme. Moreover, further simulation results are shown to investigate the robustness of the proposed control scheme to changes in some of the parameters of the system. Full article
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Open AccessArticle
Stator Current Harmonic Reduction in a Novel Half Quasi-Z-Source Wind Power Generation System
Energies 2016, 9(10), 770; doi:10.3390/en9100770 -
Abstract
The generator stator current gets distorted with unacceptable levels of total harmonic distortion (THD) because impedance-source wind power generation systems use three-phase diode rectifiers. The stator current harmonics will cause increasing losses and torque ripple, which reduce the efficiency and stability of [...] Read more.
The generator stator current gets distorted with unacceptable levels of total harmonic distortion (THD) because impedance-source wind power generation systems use three-phase diode rectifiers. The stator current harmonics will cause increasing losses and torque ripple, which reduce the efficiency and stability of the system. This paper proposes a novel half quasi-Z-source inverter (H-qZSI) for grid-connected wind power generation systems, which can reduce the generator stator current harmonics a great deal. When H-qZSI operates in the shoot-through zero state, the derivative of the generator stator current is only determined by the instantaneous value of the generator stator voltage, so the nonlinear relationship between generator stator current and stator voltage is improved compared with the traditional impedance-source inverter. Theoretically, it is indicated that the stator current harmonics can be reduced effectively by means of the proposed H-qZSI. Finally, simulation and experimental results are given to verify the theoretical analysis. Full article
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Open AccessArticle
Template-Free Fabrication of Bi2WO6 Hierarchical Hollow Microspheres with Visible-Light-Driven Photocatalytic Activity
Energies 2016, 9(10), 764; doi:10.3390/en9100764 -
Abstract
Highly hierarchical hollow bismuth tungstate (Bi2WO6) microspheres self-assembled by thin nanoplates have been fabricated via a facile template-free solvothermal route. The possible growth pattern and formation mechanism of hierarchical hollow Bi2WO6 microspheres was investigated. The [...] Read more.
Highly hierarchical hollow bismuth tungstate (Bi2WO6) microspheres self-assembled by thin nanoplates have been fabricated via a facile template-free solvothermal route. The possible growth pattern and formation mechanism of hierarchical hollow Bi2WO6 microspheres was investigated. The excellent visible-light-driven photocatalytic performance on rhodamine B (RhB) degradation was displayed by hierarchical hollow Bi2WO6 microspheres. Such well-organized hierarchical hollow Bi2WO6 microspheres show potential application in water treatment fields by full use of solar energy. Full article
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Open AccessArticle
Energy-Efficient Speed Profile Approximation: An Optimal Switching Region-Based Approach with Adaptive Resolution
Energies 2016, 9(10), 762; doi:10.3390/en9100762 -
Abstract
Speed profile optimization plays an important role in optimal train control. Considering the characteristics of an electrical locomotive with regenerative braking, this paper proposes a new algorithm for target speed profile approximation. This paper makes the following three contributions: First, it proves [...] Read more.
Speed profile optimization plays an important role in optimal train control. Considering the characteristics of an electrical locomotive with regenerative braking, this paper proposes a new algorithm for target speed profile approximation. This paper makes the following three contributions: First, it proves that under a certain calculation precision, there is an optimal coast-brake switching region—not just a point where the train should be switched from coasting mode to braking mode. This is very useful in engineering applications. Second, the paper analyzes the influence of regenerative braking on the optimal coast-brake switching region and proposes an approximate linear relationship between the optimal switching region and the regeneration efficiency. Third, the paper presents an average speed equivalent algorithm for local speed profile optimization in steep sections. In addition, this paper simplifies the proof of the optimality of smooth running on a non-steep track in two steps. The effects on energy consumption from two important factors (optimal coast and running time) are systematically analyzed. Extensive simulations verify these points of view and demonstrate that the proposed approximation approach is computationally efficient and achieves sufficient engineering accuracy. Full article
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Open AccessArticle
A Hybrid Method Based on Singular Spectrum Analysis, Firefly Algorithm, and BP Neural Network for Short-Term Wind Speed Forecasting
Energies 2016, 9(10), 757; doi:10.3390/en9100757 -
Abstract
With increasing importance being attached to big data mining, analysis, and forecasting in the field of wind energy, how to select an optimization model to improve the forecasting accuracy of the wind speed time series is not only an extremely challenging problem, [...] Read more.
With increasing importance being attached to big data mining, analysis, and forecasting in the field of wind energy, how to select an optimization model to improve the forecasting accuracy of the wind speed time series is not only an extremely challenging problem, but also a problem of concern for economic forecasting. The artificial intelligence model is widely used in forecasting and data processing, but the individual back-propagation artificial neural network cannot always satisfy the time series forecasting needs. Thus, a hybrid forecasting approach has been proposed in this study, which consists of data preprocessing, parameter optimization and a neural network for advancing the accuracy of short-term wind speed forecasting. According to the case study, in which the data are collected from Peng Lai, a city located in China, the simulation results indicate that the hybrid forecasting method yields better predictions compared to the individual BP, which indicates that the hybrid method exhibits stronger forecasting ability. Full article
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Open AccessArticle
Energy Consumption and Saving Analysis for Laser Engineered Net Shaping of Metal Powders
Energies 2016, 9(10), 763; doi:10.3390/en9100763 -
Abstract
With the increasing awareness of environmental protection and sustainable manufacturing, the environmental impact of laser additive manufacturing (LAM) technology has been attracting more and more attention. Aiming to quantitatively analyze the energy consumption and extract possible ways to save energy during the [...] Read more.
With the increasing awareness of environmental protection and sustainable manufacturing, the environmental impact of laser additive manufacturing (LAM) technology has been attracting more and more attention. Aiming to quantitatively analyze the energy consumption and extract possible ways to save energy during the LAM process, this investigation studies the effects of input variables including laser power, scanning speed, and powder feed rate on the overall energy consumption during the laser deposition processes. Considering microhardness as a standard quality, the energy consumption of unit deposition volume (ECUDV, in J/mm3) is proposed as a measure for the average applied energy of the fabricated metal part. The potential energy-saving benefits of the ultrasonic vibration–assisted laser engineering net shaping (LENS) process are also examined in this paper. The experimental results suggest that the theoretical and actual values of the energy consumption present different trends along with the same input variables. It is possible to reduce the energy consumption and, at the same time, maintain a good part quality and the optimal combination of the parameters referring to Inconel 718 as a material is laser power of 300 W, scanning speed of 8.47 mm/s and powder feed rate of 4 rpm. When the geometry shaping and microhardness are selected as evaluating criterions, American Iron and Steel Institute (AISI) 4140 powder will cause the largest energy consumption per unit volume. The ultrasonic vibration–assisted LENS process cannot only improve the clad quality, but can also decrease the energy consumption to a considerable extent. Full article
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Open AccessArticle
A Permutation Importance-Based Feature Selection Method for Short-Term Electricity Load Forecasting Using Random Forest
Energies 2016, 9(10), 767; doi:10.3390/en9100767 -
Abstract
The prediction accuracy of short-term load forecast (STLF) depends on prediction model choice and feature selection result. In this paper, a novel random forest (RF)-based feature selection method for STLF is proposed. First, 243 related features were extracted from historical load data [...] Read more.
The prediction accuracy of short-term load forecast (STLF) depends on prediction model choice and feature selection result. In this paper, a novel random forest (RF)-based feature selection method for STLF is proposed. First, 243 related features were extracted from historical load data and the time information of prediction points to form the original feature set. Subsequently, the original feature set was used to train an RF as the original model. After the training process, the prediction error of the original model on the test set was recorded and the permutation importance (PI) value of each feature was obtained. Then, an improved sequential backward search method was used to select the optimal forecasting feature subset based on the PI value of each feature. Finally, the optimal forecasting feature subset was used to train a new RF model as the final prediction model. Experiments showed that the prediction accuracy of RF trained by the optimal forecasting feature subset was higher than that of the original model and comparative models based on support vector regression and artificial neural network. Full article
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Open AccessArticle
Consumer Travel Behaviors and Transport Carbon Emissions: A Comparative Study of Commercial Centers in Shenyang, China
Energies 2016, 9(10), 765; doi:10.3390/en9100765 -
Abstract
Current literature highlights the role of commercial centers in cities in generating shopping trips and transport carbon emissions. However, the influence of the characteristics of commercial centers on consumer travel behavior and transport carbon emissions is not well understood. This study addresses [...] Read more.
Current literature highlights the role of commercial centers in cities in generating shopping trips and transport carbon emissions. However, the influence of the characteristics of commercial centers on consumer travel behavior and transport carbon emissions is not well understood. This study addresses this knowledge gap by examining shopping trips to eight commercial centers in Shenyang, China, and the CO2 emissions of these trips. We found that the locations and types of commercial centers strongly influence CO2 emissions. CO2 emissions per trip to commercial centers in the suburbs of Shenyang were on average 6.94% and 26.92% higher than those to commercial centers in the urban core and the inner city, respectively. CO2 emissions induced by wholesale centers were nearly three times higher than the lowest CO2 emissions of commercial centers in the inner city. These empirical results enhance our understanding of shopping-related transport carbon emissions and highlight the importance of optimizing urban space structure, in particular, the layout of commercial centers. Full article
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Open AccessArticle
A Novel Method to Balance and Reconfigure Series-Connected Battery Strings
Energies 2016, 9(10), 766; doi:10.3390/en9100766 -
Abstract
Cell failure and imbalance are critical problems in battery storage systems, especially in series-connected battery strings. The reconfiguration function and the balancing function are both of great importance, but it is very challenging and problematic to own both functions simultaneously. This paper [...] Read more.
Cell failure and imbalance are critical problems in battery storage systems, especially in series-connected battery strings. The reconfiguration function and the balancing function are both of great importance, but it is very challenging and problematic to own both functions simultaneously. This paper attempts to make contributions on realizing both functions through new circuits and new control strategies. Firstly, a reconfigurable balancing circuit is proposed, which is able to simultaneously balance and reconfigure the battery string. In the circuits, a new way to achieve passive balancing with no bleeding resistor is realized, and the failure cells in the battery string can be bypassed with the same circuits. By taking advantage of fewer switches in the circuits, the method owns the merits of low cost and low system complexity. Secondly, to efficiently balance and reconfigure the battery string, a control strategy is proposed according to the unique structure of the circuits. Thirdly, the reconfigurable balancing circuits are fabricated and an experimental test workbench is established. The reconfigurable balancing circuits and the control strategy are validated in the experimental test workbench. The experimental results indicate that the proposed method is able to realize both the balancing function and the reconfiguration function well, and the performance of the battery string can be maintained and improved significantly. The improvements are 13% and 34% for 4 cell- and 100 cell- series-connected battery strings, respectively. Full article
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Open AccessArticle
Experimental and Numerical Research Activity on a Packed Bed TES System
Energies 2016, 9(9), 758; doi:10.3390/en9090758 (registering DOI) -
Abstract
This paper presents the results of experimental and numerical research activities on a packed bed sensible thermal energy storage (TES) system. The TES consists of a cylindrical steel tank filled with small alumina beads and crossed by air used as the heat [...] Read more.
This paper presents the results of experimental and numerical research activities on a packed bed sensible thermal energy storage (TES) system. The TES consists of a cylindrical steel tank filled with small alumina beads and crossed by air used as the heat transfer fluid. Experimental tests were carried out while varying some operating parameters such as the mass flow rate, the inlet–outlet temperature thresholds and the aspect ratio (length over diameter). Numerical simulations were carried out using a one-dimensional model, specifically developed in the Matlab-Simulink environment and a 2D axisymmetric model based on the ANSYS-Fluent platform. Both models are based on a two-equation transient approach to calculate fluid and solid phase temperatures. Thermodynamic properties were considered to be temperature-dependent and, in the Computational Fluid Dynamics (CFD) model, variable porosity of the bed in the radial direction, thermal losses and the effective conductivity of the alumina beads were also considered. The simulation results of both models were compared to the experimental ones, showing good agreement. The one-dimensional model has the advantage of predicting the axial temperature distribution with a very low computational cost, but it does not allow calculation of the correct energy stored when the temperature distribution is strongly influenced by the wall. To overcome this problem a 2D CFD model was used in this work. Full article
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Open AccessArticle
DagTM: An Energy-Efficient Threads Grouping Mapping for Many-Core Systems Based on Data Affinity
Energies 2016, 9(9), 754; doi:10.3390/en9090754 (registering DOI) -
Abstract
Many-core processors are becoming mainstream computing platforms nowadays. How to map the application threads to specific processing cores and exploit the abundant hardware parallelism of a many-core processor efficiently has become a pressing need. This work proposes a data affinity based threads [...] Read more.
Many-core processors are becoming mainstream computing platforms nowadays. How to map the application threads to specific processing cores and exploit the abundant hardware parallelism of a many-core processor efficiently has become a pressing need. This work proposes a data affinity based threads grouping mapping strategy Data Affinity Grouping based Thread Mapping (DagTM), which categorizes threads into different groups according to their data affinity and the hardware architecture feature of many-core processors. After that, the thread groups are mapped to the specific processing cores to be energy efficiently executed. More specifically, first, the intra-thread data locality is analyzed by computing the data reuse distance, and the inter-thread data affinity is quantified by affinity matrix. Second, the threads are categorized into different groups via affinity subtree spanning algorithm. Finally, the thread groups are assigned to different processing cores through static binding. DagTM is able to reduce conflicts of the shared memory access and additional data transmission, increase utilization of the computing resources, and reduce entire system energy consumption. Experimental results show that DagTM obtains a nearly 14% improvement in computing performance, and a nearly 10% reduction in energy consumption compared with the traditional thread mapping mechanism under the condition of not introducing additional runtime overhead. Full article
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Open AccessArticle
A Flow Rate Control Approach on Off-Design Analysis of an Organic Rankine Cycle System
Energies 2016, 9(9), 759; doi:10.3390/en9090759 (registering DOI) -
Abstract
This study explored effects of off-design heat source temperature (TW,in) or flow rate (mW) on heat transfer characteristics and performance of an organic Rankine cycle system by controlling the flow rate of working fluid R245fa (i.e., [...] Read more.
This study explored effects of off-design heat source temperature (TW,in) or flow rate (mW) on heat transfer characteristics and performance of an organic Rankine cycle system by controlling the flow rate of working fluid R245fa (i.e., the operation flow rate of R245fa was controlled to ensure that R245fa reached saturation liquid and vapor states at the outlets of the preheater and evaporator, respectively). The results showed that the operation flow rate of R245fa increased with TW,in or mW; higher TW,in or mW yielded better heat transfer performance of the designed preheater and required higher heat capacity of the evaporator; heat transfer characteristics of preheater and evaporator differed for off-design TW,in and mW; and net power output increased with TW,in or mW. The results further indicated that the control strategy should be different for various off-design conditions. Regarding maximum net power output, the flow rate control approach is optimal when TW,in or mW exceeds the design point, but the pressure control approach is better when TW,in or mW is lower than the design point. Full article
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Open AccessArticle
Investigation of Energy and Environmental Potentials of a Renewable Trigeneration System in a Residential Application
Energies 2016, 9(9), 760; doi:10.3390/en9090760 (registering DOI) -
Abstract
Micro polygeneration utilizing renewable energy is a suitable approach to reduce energy consumption and carbon emission by offering high-efficiency performance, offsetting the need for centrally-generated grid electricity and avoiding transmission/distribution losses associated with it. This paper investigates the energy and environmental potential [...] Read more.
Micro polygeneration utilizing renewable energy is a suitable approach to reduce energy consumption and carbon emission by offering high-efficiency performance, offsetting the need for centrally-generated grid electricity and avoiding transmission/distribution losses associated with it. This paper investigates the energy and environmental potential of a renewable trigeneration system in a residential application under Incheon (Korea) and Ottawa (Canada) weather conditions. The trigeneration system consists of a ground-to-air heat exchanger (GAHX), photovoltaic thermal (PVT) panels and an air-to-water heat pump (AWHP). The study is performed by simulations in TRNSYS (Version 17.02) environment. The performance of the trigeneration system is compared to a reference conventional system that utilizes a boiler for space and domestic hot water heating and a chiller for space cooling. Simulation results showed substantial annual primary energy savings from the renewable trigeneration system in comparison to the reference system—45% for Incheon and 42% for Ottawa. The CO2eq emission reduction from the renewable trigeneration system is also significant, standing at 43% for Incheon and 82% for Ottawa. Furthermore, trigeneration systems’ capability to generate electricity and thermal energy at the point of use is considered as an attractive option for inclusion in the future smart energy network applications. Full article
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Open AccessArticle
High-Resolution Wave Energy Assessment in Shallow Water Accounting for Tides
Energies 2016, 9(9), 761; doi:10.3390/en9090761 (registering DOI) -
Abstract
The wave energy in a shallow water location is evaluated considering the influence of the local tide and wind on the wave propagation. The target is the coastal area just north of the Portuguese city of Peniche, where a wave energy converter [...] Read more.
The wave energy in a shallow water location is evaluated considering the influence of the local tide and wind on the wave propagation. The target is the coastal area just north of the Portuguese city of Peniche, where a wave energy converter operates on the sea bottom. A wave modelling system based on SWAN has been implemented and focused on this coastal environment in a multilevel computational scheme. The first three SWAN computational belonging to this wave prediction system were defined using the spherical coordinates. In the highest resolution computational domain, Cartesian coordinates have been considered, with a resolution of 25 m in both directions. An in-depth analysis of the main characteristics of the environmental matrix has been performed. This is based on the results of eight-year model system simulations (2005–2012). New simulations have been carried out in the last two computational domains with the most relevant wave and wind patterns, considering also the tide effect. The results show that the tide level, together with the wind intensity and direction, may influence to a significant degree the wave characteristics. This especially concerns the wave power in the location where the wave converter operates. Full article
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