Table of contents

Preface

The 2nd International Conference on New Energy and Future Energy System (NEFES2017) was held from September 22nd to 25th, 2017 in Kunming, China. The technical program comprised three keynote speakers, fifty invited speakers, five oral presentation sessions and an interesting poster session.

NEFES 2017 is sponsored by Yunnan Normal University. It aims to provide a platform for researchers and practitioners in both industry and academia to have a brainstorm, share their latest achievements and discuss the possible challenges in terms of new energy and future energy system. This volume records the proceedings of NEFES 2017 and contains 81 rigorously selected manuscripts submitted to the NEFES 2017 conference. All the manuscripts were selected depending on their quality and relevance to the conference.

The Organizing Committee would like to thank all the authors who contributed to NEFES 2017 and also the reviewers who provided their valuable comments and suggestions.

The 3rd International Conference on New Energy and Future Energy System (NEFES 2018) will be held in Shanghai, China. Everybody is welcomed to submit high quality papers to NEFES 2018! More information will be available at the conference website: http://www.intergridconf.org/2018/

Editor

Dr. Grigorios L. Kyriakopoulos

National Technical University of Athens, Greece.

All papers published in this volume of IOP Conference Series: Earth and Environmental Science have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Drying is one of the important steps in the deep processing of agricultural and sideline products. It is a main tendency to research and develop the high-efficient and energy-saving drying pattern and technology. However, it is found that drying uneven phenomenon often exists in the material-drying oven in the production practice of hot air flow drying process. In order to explore the causes of the formation of uneven phenomenon, and to propose the ways to eliminate the inhomogeneity, experimental research was conducted concerning a multifunctional drying equipment with the hot air circulation. The temperature distribution uniformity and drying efficiency in the oven were tested under no-loaded and loaded conditions, in aspect of oven tray structure improving, wind direction switching and moisture controlling of exhaust air. Experimental results show that the drying inhomogeneity and thermal efficiency could be improved by the ways of changing the wind direction from cross-flowing to cross-swept-flowing, and as well as proper moisture controlling of exhaust air.

For the standard all-glass vacuum tube collector, enhancing the vacuum tube axial natural convection can improve its thermal efficiency. According to the study of the standard all-glass vacuum tube, three kinds of guide plates which can inhibit the radial convection and increase axial natural convection are designed, and theory model is established. Experiments were carried out on vacuum tubes with three types of baffles and standard vacuum tubes without the improvement. The results show that T-type guide plate is better than that of Y-type guide plate on restraining convection and increasing axial radial convection effect, Y type is better than that of flat plate type, all guide plates are better than no change; the thermal efficiency of the tube was 2.6% higher than that of the unmodified standard vacuum tube. The efficiency of the system in the experiment can be increased by 3.1%.

Biological aviation kerosene was produced by one-step catalytic hydrotreatment of waste lard oil over Pt/SAPO-11 in a high-pressure fixed bed micro reactor. The influence of reaction conditions such as temperature, pressure, hydrogen oil ratio, and space velocity on the deoxygenation rate, the selectivity of C₈-C₁₆ hydrocarbons and the isomerization rate of C₈-C₁₆ hydrocarbons have been investigated. The experimental results showed that the temperature of 400°C, pressure of 5 MPa, hydrogen oil ratio of 1000 and space velocity of 1.2 h^-1 were the best experimental reaction conditions. Under these conditions, the conversion rate is 96.62%, the selectivity of C₈-C₁₆ hydrocarbons is 50.25%, and the isomerization rate of C₈-C₁₆ hydrocarbons is 35.68%.

With the rapid development of the aviation industry, appearing of the aviation carbon tax and the increasingly serious environmental problems have forced the world to research the development of renewable bio-aviation fuel. Renewable biological aviation fuel contains phosphorus that could reduce the synthesis of noble metal catalysts such as Pd, Pt activity. In order to get low content of phosphorus in degummed oil of non-edible vegetable oil, in this paper, with rubber seed oil as raw material, making the experiment of single factor at the influence of temperature, stirring speed, adding amount of monoethanolamine (MEA) and water amount. The experimental results show that the added amount of MEA is 2.5% in the weight of oil, and temperature is 60°C, while the amount of added water is 2% in the weight of oil, reaction time is 40 min, and stirring speed is 200 r/min. Under these conditions, the phosphorus content of rubber seed oil can be reduced to below 3 mg/kg, degumming rate is 91.37%, and the degumming effects are obvious, which also provides some foundation for follow-up studies.

To overcome the problem that the heat source temperature is limited and the lower part of the adsorption tube cannot effectively absorb the solar radiation when solar radiation as the heat source of the adsorption refrigeration system. From the perspective of enhancing the adsorption refrigeration unit tube to absorb solar radiation, thereby strengthening the heat transfer characteristic of adsorption bed, which can improve the efficiency of the refrigeration unit refrigerating capacity and system refrigeration efficiency. Solar adsorption refrigeration system based on CPC was designed and constructed in this paper. The heat and mass transfer performance of the adsorption refrigeration system were studied. The experimental results show that the temperature of the adsorption bed with parabolic concentrating structure can rise to 100°C under low irradiation condition. When the irradiation intensity is 600 w/m² and 400 w/m², the average temperature rising to desorption temperature reaches 0.67°C and 0.50°C, respectively. It can effectively solve the problem that the conventional adsorption bed is difficult to reach the required desorption temperature due to the low power density of the sunlight. In the experiment, the system COP were 0.166 and 0.143 when the system in the irradiance of 600 w/m² and 400 w/m².

Biogas slurry is one of anaerobic fermentations, and biomass fermentation biogas slurries with different compositions are different. This paper mainly presents through the anaerobic fermentation of Eichhornia crassipes solms biogas slurry and biogas slurry of corn straw, the organic components of two kinds of biogas slurry after extraction were compared by TLC, HPLC and spectrophotometric determination of nucleic acid and protein of two kinds of biogas slurry organic components, and analyzes the result of comparison.

Protein concentration process using filter membrane has a significant advantage on energy saving compared to the traditional drying processes. However, fouling on large membrane area and frequent membrane cleaning will increase the energy consumption and operation cost for the protein concentration process with filter membrane. In this study, the membrane filtration for protein concentration will be conducted and compared with the recent protein concentration technology. The analysis of operating factors for protein concentration process using filter membrane was discussed. The separation mechanism of membrane filtration was developed according to the size difference between the pore of membrane and the particle of filter material. The Darcy's Law was applied to discuss the interaction on flux, TMP (transmembrane pressure) and resistance in this study. The effect of membrane pore size, pH value and TMP on the steady-state flux (J_st) and protein rejection (R) were studied. It is observed that the J_st increases with decreasing membrane pore size, the J_st increases with increasing TMP, and R increased with decreasing solution pH value. Compare to other variables, the pH value is the most significant variable for separation between protein and water.

Battery-based energy storage has emerged as a cost-effective solution for peak reduction due to the decrement of battery's price. In this study, a battery-based energy storage system is developed and implemented to achieve an optimal peak reduction for commercial customers with the limited energy capacity of the energy storage. The energy storage system is formed by three bi-directional power converter rated at 5 kVA and a battery bank with capacity of 64 kWh. Three control algorithms, namely fixed-threshold, adaptive-threshold, and fuzzy-based control algorithms have been developed and implemented into the energy storage system in a campus building. The control algorithms are evaluated and compared under different load conditions. The overall experimental results show that the fuzzy-based controller is the most effective algorithm among the three controllers in peak reduction. The fuzzy-based control algorithm is capable of incorporating a priori qualitative knowledge and expertise about the load characteristic of the buildings as well as the useable energy without over-discharging the batteries.

Offshore wind energy has been attracting great attention. Compared with onshore wind power systems, offshore wind power applications present significantly greater economic challenges mainly due to the required bulky and costly offshore substation. To lower the cost of offshore wind power systems, various configurations are proposed in both industry and academia. The present work investigates existing offshore wind farm configurations.

This paper reports the results of the investment strategy analysis in different electricity sources. New methodology and theory of calculating the market value of the power plant and value of the electricity market supplied by it are presented. The financial gain forms the most important criteria in the assessment of an investment by an investor. An investment strategy has to involve a careful analysis of each considered project in order that the right decision and selection will be made while various components of the projects will be considered. The latter primarily includes the aspects of risk and uncertainty. Profitability of an investment in the electricity sources (as well as others) is offered by the measures applicable for the assessment of the economic effectiveness of an investment based on calculations e.g. power plant market value and the value of the electricity that is supplied by a power plant. The values of such measures decide on an investment strategy in the energy sources. This paper contains analysis of exemplary calculations results of power plant market value and the electricity market value supplied by it.

This paper reports the evaluation of a conical solar cooker. This prototype was designed in galvanized sheet with an opening diameter of 120 cm. The experiment was carried out on the roof of the building of the solar energy laboratory of FHB University. Tests of boiling eggs were carried out. During operation, two configurations of the conical cooker were adopted. In the first configuration, the cooker was used without modification. On the other hand, in the second configuration, a removable glass plate is placed in the cone and at a distance of 25 cm from the base. This contribution has the role of creating a greenhouse effect between the absorber and the glass. During the tests, the temperature of cooking, the ambient temperature as well as the solar illumination were measured. The tests were conducted in accordance with the maximum cooking time of some foods given by "Solar cookers international". Despite the observed cloudy periods, maximum temperatures obtained by the eggs were 82°C in 2 hours cooking for the first configuration and 100°C in cooking 1h10 for the second configuration. These results show that the addition of the glass plate in the conical solar cooker gives good satisfaction. In addition, in both cases, a perfect cooking of the eggs was observed.

This paper presents a systematic approach for optimizing the design of ultra-high concentrator photovoltaic (UHCPV) system comprised of non-imaging dish concentrator (primary optical element) and crossed compound parabolic concentrator (secondary optical element). The optimization process includes the design of primary and secondary optics by considering the focal distance, spillage losses and rim angle of the dish concentrator. The imperfection factors, i.e. mirror reflectivity of 93%, lens' optical efficiency of 85%, circumsolar ratio of 0.2 and mirror surface slope error of 2 mrad, were considered in the simulation to avoid the overestimation of output power. The proposed UHCPV system is capable of attaining effective ultra-high solar concentration ratio of 1475 suns and DC system efficiency of 31.8%.

Low efficiency is the key factor restricting the development of EV wireless charging systems in recent years. In order to improve the efficiency, the main circuit of the system is simplified by removing the DC/DC circuit and replacing full bridge inverter with half bridge inverter. And the output power control strategy is optimized by changing the duty cycle of PWM that controls the inverter. Besides, the peaks are reduced by changing the frequency of the system, and the output power can also be controlled by changing frequency. The performance of two most common magnetic couplers is compared and a direction of how to select couplers is given. The methods are all verified by simulations and experiments. By optimizing of the circuit and control strategy, the efficiency and the safety of the system are all improved.

In order to improve the situation of voltage violation caused by the grid-connection of photovoltaic (PV) system in a distribution network, a bi-level programming model is proposed for battery energy storage system (BESS) deployment. The objective function of inner level programming is to minimize voltage violation, with the power of PV and BESS as the variables. The objective function of outer level programming is to minimize the comprehensive function originated from inner layer programming and all the BESS operating parameters, with the capacity and rated power of BESS as the variables. The differential evolution (DE) algorithm is applied to solve the model. Based on distribution network operation scenarios with photovoltaic generation under multiple alternative output modes, the simulation results of IEEE 33-bus system prove that the deployment strategy of BESS proposed in this paper is well adapted to voltage violation regulation invariable distribution network operation scenarios. It contributes to regulating voltage violation in distribution network, as well as to improve the utilization of PV systems.

In this context, a typical lead-acid battery producing process is introduced. Based on the formation process, an efficiency management method is proposed. An optimization model with the objective to minimize the formation electricity cost in a single period is established. This optimization model considers several related constraints, together with two influencing factors including the transformation efficiency of IGBT charge-and-discharge machine and the time-of-use price. An example simulation is shown using PSO algorithm to solve this mathematic model, and the proposed optimization strategy is proved to be effective and learnable for energy-saving and efficiency optimization in battery producing industries.

Sun-tracking is an important mechanism to boost the electricity generation from photovoltaic systems by adjusting the orientation of the systems to receive more solar radiation. However, compared to the fixed-array systems, the use of the single-axis and dual-axis sun-tracking systems is usually impeded by increased cost, decreased reliability, and cumbersome maintenance. In this paper, we compare the performance of fixed-array, single-axis, and dual-axis rooftop photovoltaic systems in California using the data envelopment analysis method. For each system, an efficiency score is computed based on capacity, electricity generation, system cost, module use, solar irradiance and ambient temperature. We find the single-axis systems perform significantly better than the fixed-array and dual-axis systems. The fixed-array systems are more efficient than the dual-axis systems but the difference is not significant. The results imply the policymakers and solar installers should promote the single-axis sun-tracking and be cautious of using the dual-axis systems.

Generally, polymer electrolyte fuel cells (PEFCs) need humidifiers to prevent the drying of the membrane, but this use of humidifiers creates water management issues, such as the flooding/plugging phenomena and decreased system efficiency because of an increase in the electric energy needed for auxiliary equipment. Although most researchers have developed high-temperature membranes that do not need humidifiers, a lot of time is necessary for the development of these membranes, and these membranes drive up costs. Therefore, we propose a new cathode separator design that can recycle water generated by power generation in the same cell and a stack structure that can redistribute water collected in the cathode outlet manifold to drying cells. Because the new cathode separator has a bypass channel from the gas outlet to the gas inlet to transport excess water, a dry part in the gas inlet is supplied with excess water in the gas outlet through the bypass channel even if the PEFC is operated under dry conditions. Excess water in the PEFC stack can be transported from the cell with excess water to the drying cell through the cathode outlet manifold with a porous wall. Therefore, we confirm the influence of the plugging phenomenon in the cathode gas outlet manifold on the cell performance of each cell in the stack. As a result, the cell performance of the new cathode separator design is better than that of the standard separator under the low humidity conditions. We confirm that the plugging phenomenon in the cathode outlet manifold affects the cell performance of each cell in the stack.

The comparative experimental analysis of flow boiling of pure water and four different self-rewetting fluids (6% butanol, 2% pentanol, 0.6% hexanol and 0.15% heptanol aqueous solution) was performed in an array of interconnected 50×50 μm microchannels. The results show that the onset of boiling was postponed to higher surface superheats when SRFs were used instead of water. In addition, the visualization of the flow boiling of self-rewetting fluids showed a substantially more abrupt and unstable flow, which was observed as a misty two-phase flow in the microchannel array. Both occurrences are attributable to (i) the absence of properly sized nucleation cavities in the microchannels and (ii) higher achieved temperatures during boiling of self-rewetting fluids, which lead to a higher momentum force of the emerging vapor phase. The measured static and dynamic contact angles and therefore also the surface tension of the used self-rewetting fluids are lower in comparison with water.

We have developed micro generation system for effective use of unutilized energy and the spread of a self-controlled dispersion energy supply system. The turbine blade was designed for achieving high performance by special shape. The turbine type was called quasi-Peace turbine type. Turbine with a diameter of 30cm is made of metal, it was created by the 5-axis milling machine. The experimental apparatus was fabricated by the 3D printer. An experiment was carried out in the scale down model. The specific speed of this turbine was much lower than that of existing turbines.

Currently, electric energy is used in practically all modern human activities. Most of the energy produced came from fossil fuels, making irreversible damage to the environment. Lately, there has been an effort by nations to produce energy using clean methods, such as solar and wind energy, among others. Wind energy is one of the cleanest alternatives. However, the wind speed is not constant, making the planning and operation at electric power systems a difficult activity. Knowing in advance the amount of raw material (wind speed) used for energy production allows us to estimate the energy to be generated by the power plant, helping the maintenance planning, the operational management, optimal operational cost. For these reasons, the forecast of wind speed becomes a necessary task. The forecast process involves the use of past observations from the variable to forecast (wind speed). To measure wind speed, weather stations use devices called anemometers, but due to poor maintenance, connection error, or natural wear, they may present false or missing data. In this work, a hybrid methodology is proposed, and it uses a compact genetic algorithm with an artificial neural network to reconstruct wind speed time series. The proposed methodology reconstructs the time series using a ANN defined by a Compact Genetic Algorithm.

In this paper, study on metal aluminum solid and fluid conversion was carried out by using crucible resistance furnace, and observing the phenomenon of metal aluminum solid and fluid conversion. In the experiment, the same shape aluminum block was kept under the same heating rate and heated by the resistance furnace. The experimental results show that the melting point of metal aluminum is between 650°C and 660°C, and after the melting point, the metal aluminum began to melt when it maintained for a long period of time, however, when the temperature is higher than the melting point, the aluminum will melt very quickly. In addition, in ANSYS simulation, the solid aluminum melted completely at 670°C in 5430 seconds, much longer than the actual experiment, it due to the heating rate was faster, not in an ideal experimental environment and there is heat exchange with the outside world and convection, at the same time, the aluminum block may contain impurities, so the actual melting time could be shorter than the simulation. In this paper, it was explored for the liquid and solid conversion in depth, and had a certain actual value.

Using the experimental method, the experimental research of creep properties were conducted under different temperature ranging from 10°C to 60°C. The similar material of new soft rock consists of paraffin, which can obtain that the deformation contains the instantaneous elastic deformation and creep deformation through the uniaxial creep experimental results. And thus the increase of temperature has great influence on the creep characteristics of similar soft rock according to the creep curve of similar soft rock at 10°C to 60°C. With the increase of temperature, the slope of the stress-strain curve of similar soft rock is increasing, while the average of the creep modulus is decreasing, which means that the capacity of resist deformation is reduced. Therefore, the creeps law of high-temperature and short-time can be shown the creep phenomenon of low-temperature and long-time, and further shorten the creep experimental cycle.

Heat transfer fluid is one critical component for transferring and storing heat energy in concentrating solar power systems. Molten-salt mixtures can be used as high temperature heat transfer fluids because of their thermophysical properties. This paper studied the thermophysical properties of Li₂CO₃-Na₂CO₃-K₂CO₃ eutectic salt and three eutectic chloride salts NaCl-KCl-ZnCl₂ with different compositions in the range of 450-600°C and 250-800°C, respectively. Properties including specific heat capacity, thermal conductivity, density and viscosity were determined based on imperial correlations and compared at different operating temperatures. The heat transfer coefficients of using different eutectic salts as heat transfer fluids were also calculated and compared in their operating temperature range. It is concluded that all the four eutectic salts can satisfy the requirements of a high-temperature heat transfer fluid.

In order to select effective samples in the large number of data of PV power generation years and improve the accuracy of PV power generation forecasting model, this paper studies the application of clustering analysis in this field and establishes forecasting model based on neural network. Based on three different types of weather on sunny, cloudy and rainy days, this research screens samples of historical data by the clustering analysis method. After screening, it establishes BP neural network prediction models using screened data as training data. Then, compare the six types of photovoltaic power generation prediction models before and after the data screening. Results show that the prediction model combining with clustering analysis and BP neural networks is an effective method to improve the precision of photovoltaic power generation.

Solar irradiation and ambient temperature are characterized by region, season and time-domain, which directly affects the performance of solar energy based car system. In this paper, the model of solar electric cars used was based in Xi'an. Firstly, the meteorological data are modelled to simulate the change of solar irradiation and ambient temperature, and then the temperature change of solar cell is calculated using the thermal equilibrium relation. The above work is based on the driving resistance and solar cell power generation model, which is simulated under the varying radiation conditions in a day. The daily power generation and solar electric car cruise mileage can be predicted by calculating solar cell efficiency and power. The above theoretical approach and research results can be used in the future for solar electric car program design and optimization for the future developments.

As the important Environmental Interests of Subjects, government behooves to undertake the corresponding responsibility of Pollution Control and Environmental Protection. The current situations in our country, however, appear as government environmental responsibility failure. Based on the analysis of law and economics, this article reaches the conclusion through game analysis, principle-agency relationship and utility theory that the prisoners dilemma of environmental interest game between government and enterprise, and the inherent defect of the principal-agency relationship between central government and local government are the inherent causes of government environmental responsibility failure. Many officials tends to graft and corrupt to maximum their own benefit, thus leading to the government failure among environmental pollution treatment and the environmental responsibility to undertake.

As the important Environmental Interests of Subjects, enterprises behoove to undertake the corresponding responsibility of Pollution Control and Environmental Protection. The current situations in our country, however, appear as the serious lack of enterprise environmental responsibility. Based on the analysis of law and economics, this article reaches the conclusion through game analysis and cost-benefit analysis that the prisoners dilemma of environmental interest game between enterprises is the inherent causes for the serious defect of enterprise environmental responsibility. Meanwhile, at the point of cost-benefit, the externality of environment illegal act results in the imbalanced cost-benefit, lacking of the motivation to control pollution and protect environment in an active way.

As the important environmental interests subject, enterprises, public and government should assume the corresponding responsibility of pollution control and environmental protection. However, in the aspect of environment, there are failure existing in performing government responsibility, the financial expense and investment our government has participated in the aspects of pollution control and environmental protection are serious insufficient. In the meantime, in spite of the clear definition of the range and principles of enterprises' environmental responsibility according to some corresponding law documents, in view of our country's condition, enterprises always fail to assume their own environmental responsibility, and there are cases existing in pollution control and environmental protection that the investment is insufficient and the treatment effect is not obvious. In addition, it is especially outstanding in our country that the awareness of public environmental rights is pretty weak. The issues of ecological damage and environmental pollution get worse and worse and the total environmental interests get injured seriously because of the failure and vacancy of environmental responsibility of different subjects of right.

Local government should be regarded as the main subject to be stipulated by environmental law, thus to avoid local government's alignment with commercial interests. Such a shift would, furthermore, discourage collusion against environment law or speculative behaviors motivated by maximizing production at the expense of environment pollution. Moreover, whether companies make proactive decisions to prevent pollution or not depends on the severity of appropriate environment legal system's sanctions for their action. It would encourage enterprises to undertake their own environmental responsibility if environmental law could further enhance their environmental liability. In addition, public environmental rights should be embedded into environmental law. In this way, the public may become more aware of their environmental rights as well as the positivity of total environmental interests.

Transformers are essential devices of the power system. The accurate computation of the highest temperature (HST) of a transformer's windings is very significant, as for the HST is a fundamental parameter in controlling the load operation mode and influencing the life time of the insulation. Based on the analysis of the heat transfer processes and the thermal characteristics inside transformers, there is taken into consideration the influence of factors like the sunshine, external wind speed etc. on the oil-immersed transformers. Experimental data and the neural network are used for modeling and protesting of the HST, and furthermore, investigations are conducted on the optimization of the structure and algorithms of neutral network are conducted. Comparison is made between the measured values and calculated values by using the recommended algorithm of IEC60076 and by using the neural network algorithm proposed by the authors; comparison that shows that the value computed with the neural network algorithm approximates better the measured value than the value computed with the algorithm proposed by IEC60076.

In this paper, heat conduction problems are analyzed from the view of information entropy. The variation law of temperature with time in the lumped-heat-capacity system can be expressed in the form of exponential distribution. It is proved that exponential distribution is the solution of a conditional extreme value problem with information entropy as an objective function. The general analysis procedure of heat conduction problems from the view of information entropy is proposed. Fundamental solution of heat conduction equation can be written in the form of normal distribution, and normal distribution can be derived from the maximum entropy principle.

Flue gas desulfurization (FGD) has been implemented for sulfur dioxide gas emission reduction by pyrolusite in iron ore sintering. However, the mechanism of SO₂ reduction through FGD is still not fully clear. And in present work, the effects of operating conditions on desulfurization rate and Mn²⁺ leaching rate of pyrolusite were investigated. Six hours later, the desulfurization rate and Mn²⁺ leaching rate all can be higher than 70%. And a higher absorption temperature was good for desulfurization rate, while a middle temperature was good for Mn²⁺ leaching rate. A higher manganese ore granularity and SO₂ concentration were good for desulfurization rate and Mn²⁺ leaching rate. However, a higher liquid-solid rate was only good for desulfurization rate, but Mn²⁺ leaching rate. The results demonstrate that the pyrolusite is a kind of very promising adsorbent in industrial flue gas desulfurization application due to its low cost and good desulfurization capacity.

Orthogonal experiments were conducted to study the effect of each single factor on the desulfurization rate and leaching rate of Mn²⁺ to obtain improved process parameters. The results showed that the use of pyrolusite flue gas and the process method of by-product MnSO₄ can not only effectively remove the sulfur in the gas, thereby controlling environmental pollution, but can also recover sulfur.

Oil provides a powerful impetus for modern society's production and life. The influences of oil price fluctuations on socio-economic development are obvious, and it draws more attention from scholars. However, the distribution of oil is highly centralized, which leads to the vast majority of oil trading through foreign trade. As a result, exchange rate plays an important role in the oil business. Study on the relationship between exchange rate and crude oil gradually becomes a hot research topic in recent years. In this paper, we use copula and CARR model to study correlation structure and relationship between crude oil price and exchange rate. We establish CARR models as marginal models and use five copulas which are Gaussian Copula, Student-t Copula, Gumbel Copula, Clayton Copula and Frank Copula to study the correlation structure between NYMEX crude oil price range and U. S. Dollar Index range. Furthermore, we use Copula-CARR model with structural breaks to detect the change points in the correlation structure between NYMEX crude oil price range and U. S. Dollar Index range. Empirical results show that the change points are closely related to the actual economic events.

This paper aims to analyze the energy efficiency of water electrolysis under high pressure and high temperature conditions. The effects of temperature and pressure on four different kinds of reaction mechanisms, namely, reversible voltage, activation polarization, ohmic polarization, and concentration polarization, are investigated in details. Results show that the ohmic and concentration over-potentials are increased as temperature is increased, however, the reversible and activation over-potentials are decreased as temperature is increased. Therefore, the net efficiency is enhanced as temperature is increased. The efficiency of water electrolysis at 350°C/100 bars is increased about 17%, compared with that at 80°C/1bar.

The city conducted groundwater artificial recharge test which was taken a typical site as an example, and the purpose is to prevent and control land subsidence, increase the amount of groundwater resources. To protect groundwater environmental quality and safety, the city chose tap water as recharge water, however, the high cost makes it not conducive to the optimal allocation of water resources and not suitable to popularize widely. To solve this, the city selects two major surface water of River A and B as the proposed recharge water, to explore its feasibility. According to a comprehensive analysis of the cost of recharge, the distance of the water transport, the quality of recharge water and others. Entropy weight Fuzzy Comprehensive Evaluation Method is used to prefer tap water and water of River A and B. Evaluation results show that water of River B is the optimal recharge water, if used; recharge cost will be from $0.4724/m³ to $0.3696/m³. Using Entropy weight Fuzzy Comprehensive Evaluation Method to confirm water of River B as optimal water is scientific and reasonable. The optimal water management decisions can provide technical support for the city to carry out overall groundwater artificial recharge engineering in deep aquifer.

Offshore wind farms promise to become an important source of energy in the near future. The high-rise pile cap foundation is one of the typical foundation types for offshore wind turbine. This paper introduces the structural characteristics and construction technology of high-rise pile cap foundation, aiming at the characteristics of the sea area of Taiwan Strait and combining with engineering examples. The construction technology of high-rise pile cap foundation is expounded emphatically from the manufacture and transportation of steel pipe piles, pile foundation construction and bearing platform construction. Compared with the traditional construction technology, the construction technologies used in this project are safer and more reliable. The construction period of piles cap foundation is shortened by 10 ∼ 48 days. The construction technology provides reference for offshore wind power foundation construction.

In order to achieve the targets for energy conservation and economic development goals in Jiangsu Province under the constraint of carbon emission, this paper uses the gray GM (1,1) model to predict and optimize the consumption structure of major energy sources (coal, oil, natural gas, etc.) in Jiangsu province in the "13th Five-Year" period and the next seven years. The predictions meet the requirement of reducing carbon dioxide emissions per unit GDP of China by 50%. The results show that the proposed approach and model is effective. Finally, we put forward opinions and suggestions on the way of energy-saving and emission-reduction, the adjustment of energy structure and the policy of coal consumption in Jiangsu Province.

This paper has studied the Off-design characteristic of low temperature economizer system based on thermodynamics analysis. Based on the data from one 1000 MW coal-fired unit, two modes of operation are contrasted and analyzed. One is to fix exhaust gas temperature and the other one is to take into account both of the average temperature difference and the exhaust gas temperature. Meanwhile, the cause of energy saving effect change is explored. Result shows that: in mode 1, the amount of decrease in coal consumption reduces from 1.11 g/kWh (under full load) to 0.54 g/kWh (under half load), and in mode 2, when the load decreases from 90% to 50%, the decrease in coal consumption reduces from 1.29 g/kWh to 0.84 g/kWh. From the result, under high load, the energy saving effect is superior, and under lower work load, energy saving effect declines rapidly when load is reduced. When load changes, the temperature difference of heat transfer, gas flow, the flue gas heat rejection and the waste heat recovery change. The energy saving effect corresponding changes result in that the energy saving effect under high load is superior and more stable. However, rational adjustment to the temperature of outlet gas can alleviate the decline of the energy saving effect under low load. The result provides theoretical analysis data for the optimal design and operation of low temperature economizer system of power plant.

Lithium-ion (Li-ion) battery is a core component for various industrial systems, including satellite, spacecraft and electric vehicle, etc. The mechanism of performance degradation and remaining useful life (RUL) estimation correlate closely to the operating state and reliability of the aforementioned systems. Furthermore, RUL prediction of Li-ion battery is crucial for the operation scheduling, spare parts management and maintenance decision for such kinds of systems. In recent years, performance degradation prognostics and RUL estimation approaches have become a focus of the research concerning with Li-ion battery. This paper summarizes the approaches used in Li-ion battery RUL estimation. Three categories are classified accordingly, i.e. model-based approach, data-based approach and hybrid approach. The key issues and future trends for battery RUL estimation are also discussed.

With the energy crisis and the increasing environmental pollution, more and more efforts have been made about wind power development. In this paper, a four blades bionic wind turbine was proposed, and the outline of wind turbine was constructed by the fitted curve. This paper attempted to research the effects of setting angle and chord length on performance of four blades bionic wind turbine by computational fluid dynamics (CFD) simulation. The results showed that the setting angle and chord length of the bionic wind turbine has some significant effects on the efficiency of the wind turbine, and within the range of wind speed from 7 m/s to 15 m/s, the wind turbine achieved maximum efficiency when the setting angle is 31 degree and the chord length is 125 mm. The conclusion will work as a guideline for the improvement of wind turbine design

An advanced voltage sag detection method and compensation technique can improve the power quality of the distribution network to a entirely new level. A high performance voltage sag detection method demands fast response and good accuracy, even detecting distorted grid voltage sag caused by new energy accessing to distribution network. The voltage sag detection method, based on sliding window iterative discrete fourier transfer (DFT) algorithm, has excellent filtering ability but long detection time. On the other hand, the voltage sag detection method, based on nonrecursive DFT algorithm, has short detection time but poor filtering ability. Aiming to meet the requirements of fast response and good accuracy, this paper proposed a voltage sag detection method based on improved nonrecursive DFT algorithm. By means of disturbance filter, which is combined with several notch filters and a low-pass filter, the filter characteristic of nonrecursive DFT algorithm has been improved, and the detection delay time is reduced. The proposed algorithm can guarantee shorter detection time and higher detection accuracy.

This paper puts forth a rolling modification strategy for day-ahead scheduling of electric power system with wind power, which takes the operation cost increment of unit and curtailed wind power of power grid as double modification functions. Additionally, an improved Nondominated Neighbor Immune Algorithm (NNIA) is proposed for solution. The proposed rolling scheduling model has further improved the operation cost of system in the intra-day generation process, enhanced the system's accommodation capacity of wind power, and modified the key transmission section power flow in a rolling manner to satisfy the security constraint of power grid. The improved NNIA algorithm has defined an antibody preference relation model based on equal incremental rate, regulation deviation constraints and maximum & minimum technical outputs of units. The model can noticeably guide the direction of antibody evolution, and significantly speed up the process of algorithm convergence to final solution, and enhance the local search capability.

Traditional power equipment, power-grid structures, and operation technology are becoming increasingly powerless with the large-scale renewable energy access to the grid. Thus, we must adopt new technologies, new equipment, and new grid structure to satisfy future requirements in energy patterns. Accordingly, the multiterminal direct current (MTDC) transmission system is receiving increasing attention. This paper starts with a brief description of current developments in MTDC worldwide. The MTDC project, which has been placed into practical operation, is introduced by the Italian–Corsica–Sardinian three-terminal high-voltage DC (HVDC) project. We then describe the basic characteristics and regulations of multiterminal DC transmission. The current mainstream of several control methods are described. In the third chapter, the key to the development of MTDC system or hardware and software technology that restricts the development of multiterminal DC transmission is discussed. This chapter focuses on the comparison of double-ended HVDC and multiterminal HVDC in most aspects and subsequently elaborates the key and difficult point of MTDC development. Finally, this paper summarizes the prospect of a DC power grid. In a few decades, China can build a strong cross-strait AC-DC hybrid power grid.

To improve the power line communication distance, shorten the networking time and the reliability of the system communication, a method based on the clustering algorithm to change the network time and based on the distance between nodes is proposed in this paper. Firstly, the physical structure and logical topology of the low-voltage power line network are described in details. Then, the clustering algorithm and the method of route reconstruction are described. Finally, the method is simulated and analyzed. The results show that the proposed method can not only reduce network time, but also improve the communication stability of nodes within the network.

How to raise the efficiency of energy storage and maximize storage capacity is a core problem in current energy storage management. For that, two-stage energy storage equalization system which contains two-stage equalization topology and control strategy based on a symmetric multi-winding transformer and DC-DC (direct current-direct current) converter is proposed with bidirectional active equalization theory, in order to realize the objectives of consistent lithium-ion battery packs voltages and cells voltages inside packs by using a method of the Range. Modeling analysis demonstrates that the voltage dispersion of lithium-ion battery packs and cells inside packs can be kept within 2 percent during charging and discharging. Equalization time was 0.5 ms, which shortened equalization time of 33.3 percent compared with DC-DC converter. Therefore, the proposed two-stage lithium-ion battery equalization system can achieve maximum storage capacity between lithium-ion battery packs and cells inside packs, meanwhile efficiency of energy storage is significantly improved.

At less than 30% electrification, Tropical Africa is the most energy-poor electrified region of the world. At home level, the annual per-capita electric energy consumption ranges between 0 and 150 kWh in rural areas, where 83% of the population reside. This is well below the 250 kWh recommended by the International Energy Agency (IEA) as the threshold for exiting rural 'Energy Poverty'. Some governments have tried to extend the grid to such areas but these efforts have not yielded much. The approaches of rural electrification – as is being done now have therefore failed – and they may not be able to electrify every home in the countries concerned. An alternative approach promoting stand-alone photovoltaic (PV) and other solar powered heat and mass transfer systems at home level is proposed. An example of the approach in a village home in rural Uganda, East Africa is given. It is estimated that the combined unit energy cost over the systems' lifespan would be just about US 3 cents. Health, Education, and Sustainability in all its forms would be greatly improved. The main recommendation is for policy makers to adopt this approach for rural homes while sparing grid supply only for commercial and industrial activities.

This paper presents the design of a low-cost data acquisition system for monitoring a photovoltaic system's electrical quantities, battery temperatures, and state of charge of the battery. The electrical quantities are the voltages and currents of the solar panels, the battery, and the system loads. The system uses an Atmega328p microcontroller to acquire data from the photovoltaic system's charge controller. It also records individual load information using current sensing resistors along with a voltage amplification circuit and an analog to digital converter. The system is used in conjunction with a wall power data acquisition system for the recording of regional power outages. Both data acquisition systems record data in micro SD cards. The data has been successfully acquired from both systems and has been used to monitor the status of the PV system and the local power grid. As more data is gathered it can be used for the maintenance and improvement of the photovoltaic system through analysis of the photovoltaic system's parameters and usage statistics.

A solar photovoltaic/thermal (PV/T) module based on internally extruded fin flow channel was investigated numerically in this paper. First of all, the structures of the thin plate heat exchanger and the PV/T module were presented. Then, a numerical model of the PV/T module considering solar irradiation, fluid flow and heat transfer was developed to analyze the performance of the module. Finally, the steady electrical and thermal efficiencies of the PV/T module at different inlet water temperatures and mass flow rates were achieved. These numerical results supply theory basis for practical application of the PV/T module.

Nowadays, more and more people are beginning to use hybrid vehicles (HVs). The drive system of HVs needs to produce the electric energy with the electric generator and gearbox powered by an engine. Therefore, the structure becomes complex and the cost is high. To solve this issue, this research proposes a new drive system design that combines the engine and a linear switched reluctance generator (LSRG). When the engine is operating, the LSRG can simultaneously assist the engine's mechanical output or can generate power to charge the battery. In this research, three research steps are executed. In the first step, the LSRG is designed according to the size of normal engine. Then, finite element analysis is used to get the data of flux linkage and calculate the inductance and translator force. Finally, Simulink models of control system are constructed to verify the performance of LSRG.

Light intensity directly affects the output current of photovoltaic (PV) modules. The output characteristics of underwater photovoltaic modules are directly affected by light intensity. In this paper, utilizing the matrix simulation of light, and solar module analyzer (PROVA) test equipment, the electrical parameters of polycrystalline silicon PV modules are tested underwater. The relationship between the output characteristics of the PV module and water depth is analyzed. The results show that the output characteristics of PV modules is insensitive to increasing water depth. For the vertically irradiated photovoltaic module, the short-circuit current of the silicon photovoltaic module decreased by 2.39 A, the power decreased by 2.57 W, and the efficiency decreased by 5% when the water depth was increased by 1 cm. Similarly, the when the dip angle is 30 degrees, 45 degrees, 60 degrees, with an increase of water depth by 1cm, the PV module of short-circuit current, power and efficiency were decreased by 2.05 A, 2.1 W, 8%; 1.85 A, 2.07 W, 6.93%; 1.05 A, 0.74 W, 3.67%, respectively. Relative to the 0 degree angle, when the dip angle is 30 degrees, 45 degrees, 60 degrees angle, the percentage drop in PV module of short circuit current is14%, 23%, 56% and the power is 18.3%, 19.5%, 71.2% respectively.

Dish-Stirling concentrated solar power system (DS-CSP) is an important pathway for converting solar energy into electricity at high efficiency. In this study, a rated power 38 kW DS-CSP system was developed (installed in Xiangtan Electric Manufacturing Group). The heat engine adopted the alpha-type four cylinders double-acting Stirling engine (Stirling Biopower Flexgen S260). The absorber flux distribution simulation was conducted using ray tracing method and then the 204 m² parabolic dish concentrator system (diameter is 17.70 m and focal length is 9.49 m) with single concentrator plus single pillar supporting has been designed and built. A water-cooled disc target and an absorber imitation device were adopted to test the tracking performance of the dish concentrator system, homogeneity of the focal spot and flux distribution of the absorber. Finally, the S260 Stirling engine was installed on the focal position of the dish concentrator and then the net output power date of the 38 kW DS-CSP system was tested. The absorber overheating problem on the DS-CSP system performance was discussed when the DS-CSP system was installed in different locations. The testing result shows that this system achieved the net output power of 38 kW and solar-to-electricity efficiency (SEE) of 25.3% with the direct normal irradiation (DNI) at 750 W/m². The net output power can further increase to 40.5 kW with the SEE of 26.6% when the DNI reaches up to the maximum of 761 W/m². The net output power of the 38 kW DS-CSP system has a linear function relationship with the DNI. The fitting function is Net power output=0.1003×DNI－36.129, where DNI is at the range of 460∼761 W/m². This function could be used to predict the amount of the 38 kW DS-CSP system annual generation power.

Residents of Southern China are increasingly concerned about the space heating in winter. The chief aim of the present work is to find a cost-effective way for residential space heating in Shanghai, one of the biggest city in south China. Economic and energy efficiency of three residential space heating ways, including ground source heat pump (GSHP), air source heat pump (ASHP) and wall-hung gas boiler (WHGB), are assessed based on Long-term measured data. The results show that the heat consumption of the building is 120 kWh/m²/y during the heating season, and the seasonal energy efficiency ratio (SEER) of the GSHP, ASHP and WHGB systems are 3.27, 2.30, 0.88 respectively. Compared to ASHP and WHGB, energy savings of GSHP during the heating season are 6.2 kgce/(m².y) and 2.2 kgce/(m².y), and the payback period of GSHP are 13.3 and 7.6 years respectively. The sensitivity analysis of various factors that affect the payback period is carried out, and the results suggest that SEER is the most critical factor affecting the feasibility of ground source heat pump application, followed by building load factor and energy price factor. These findings of the research have led the author to the conclusion that ground source heat pump for residential space heating in Shanghai is a good alternative, which can achieve significant energy saving benefits, and a good system design and operation management are key factors that can shorten the payback period.

The most frequently used refrigerants in the refrigeration and air conditioning (RAC) sector in Mauritius are currently hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC). However, because of their strong influence on global warming and the impact of HCFCs on the ozone layer, refrigerants such as ammonia (NH₃), carbon dioxide (CO₂) and Hydrocarbons (HC), having minimal impact on the environment, are being considered. So far, HCs have only been safely used in domestic refrigeration. Ammonia has been used mainly for industrial refrigeration whereas CO₂ is still under study. In this paper, a comparative study of the various feasible alternatives is presented in a survey that was undertaken with major stake holders in the field. The retrofitting possibility of existing equipment was assessed and safety issues associated with each refrigerant were analysed. The major setback of hydrocarbons as a widely accepted refrigerant is its flammability which was considered as a major safety hazard by the majority of respondents in the survey and the main advantages are the improved equipment coefficient of performance (COP) and better TEWI factor. This resulted in a 12 % drop in energy consumption. Despite the excellent thermodynamic properties of ammonia, its use has mainly been confined to industrial refrigeration due to its toxicity. In Mauritius, the performance of ammonia in air conditioning is being evaluated on a pilot basis. The major setback of carbon dioxide as a refrigerant is the high operating pressure which is considered a safety hazard. The high initial investment cost and the lack of qualified maintenance technician is also an issue. The use of CO₂ is mainly being considered in the commercial refrigeration sector.

Energy consumption of residential buildings has grown fast in recent years, thus raising a challenge on zero energy residential building (ZERB) systems, which aim at substantially reducing energy consumption of residential buildings. Thus, how to facilitate ZERB has become a hot but difficult topic. In the paper, we put forward the overall design principle of ZERB based on analysis of the systems' energy demand. In particular, the architecture for both schematic design and passive technology is optimized and both energy simulation analysis and energy balancing analysis are implemented, followed by committing the selection of high-efficiency appliance and renewable energy sources for ZERB residential building. In addition, Chinese classical residential building has been investigated in the proposed case, in which several critical aspects such as building optimization, passive design, PV panel and HVAC system integrated with solar water heater, Phase change materials, natural ventilation, etc., have been taken into consideration.

Solar photovoltaic systems are commonly utilized in China. However, the associated research is still lack of its resource potential analysis in all regions in China. Based on the existed data about solar radiation and system conversion efficiency data, a new method for distributed photovoltaic potential assessment has been presented. The experiment of three kinds of solar photovoltaic system has been set up for the purpose of analyzing the relationship between conversion efficiency and environmental parameters. This paper fits the relationship between conversion efficiency and solar radiation intensity. This method takes into account the amount of solar radiation that is effectively generated and drives away the weak values. With the spatial analysis function of geographic information system (GIS) platform, frequency distribution of solar radiation intensity and PV potential in China can be derived. Furthermore, analytical results show that monocrystalline-silicon PV generation in the north-western and northern areas have reached a level of more than 200 kWh/(m².a), making those areas be suitable for the development of PV system. However, the potential for southwest areas reaches a level of only 130 kWh/(m².a). This paper can provide the baseline reference for solar energy development planning.

In this study, a laser holographic interferometer experimental system was developed for studying the gas-liquid mass diffusion coefficient. Then the experimental system's uncertainty was analyzed to be at most ±0.2%; therefore, this system was reliable. The mass diffusion coefficient of hydrogen in dimethyl phosphate and n-heptane was measured at atmospheric pressure in the temperature range of 273.15–338.15 K. Then, the experimental data were used to fit the correlations of the mass diffusion coefficient of hydrogen in dimethyl phosphate and n-heptane with temperature.

The functional performance, such as magnetic flux leakage, power density and efficiency, is related to the structural characteristics and design technique for the disc permanent magnet synchronous generators (PMSGs). Halbach array theory-based magnetic circuit structure is developed, and Maxwell3D simulation analysis approach of PMSG is proposed in this paper for integrated starter generator (ISG). The magnetization direction of adjacent permanent magnet is organized in difference of 45 degrees for focusing air gap side, and improving the performance of the generator. The magnetic field distribution and functional performance in load and/or unload conditions are simulated by Maxwell3D module. The proposed approach is verified by simulation analysis, the air gap flux density is 0.66T, and the phase voltage curve has the characteristics of a preferable sinusoidal wave and the voltage amplitude 335V can meet the design requirements while the disc coreless PMSG is operating at rated speed. And the developed magnetic circuit structure can be used for engineering design of the disc coreless PMSG to the integrated starter generator.

Gas pipeline network is a major hazard source in urban areas. In the event of an accident, there could be grave consequences. In order to understand more clearly the causes and consequences of gas pipeline network accidents, and to develop prevention and mitigation measures, the author puts forward the application of improved bow-tie model to analyze risks of urban gas pipeline network. The improved bow-tie model analyzes accident causes from four aspects: human, materials, environment and management; it also analyzes the consequences from four aspects: casualty, property loss, environment and society. Then it quantifies the causes and consequences. Risk identification, risk analysis, risk assessment, risk control, and risk management will be clearly shown in the model figures. Then it can suggest prevention and mitigation measures accordingly to help reduce accident rate of gas pipeline network. The results show that the whole process of an accident can be visually investigated using the bow-tie model. It can also provide reasons for and predict consequences of an unfortunate event. It is of great significance in order to analyze leakage failure of gas pipeline network.

3.0 MeV proton-irradiation effects on the GaAs middle cell and the GaInP top cell of n⁺-p GaInP/GaAs/Ge triple-junction (3J) solar cells have been analyzed using temperature-dependent photoluminescence (PL) technique. The E5 (E_c - 0.96 eV) electron trap in the GaAs middle cell, the H2 (E_v + 0.55 eV) hole trap in the GaInP top cell are identified as the proton irradiation-induced non-radiative recombination centers, respectively, causing the performance degradation of the triple-junction solar cells. The GaAs middle cell is less resistant to proton irradiation than the GaInP top cell.

The problem that misalignment between the transmitting coil and the receiving coil significantly impairs the transmission power and efficiency of the system has been attached more and more attention. In order to improve the uniformity of the magnetic field between the two coils to solve this problem, a new type of coil called pan-shaped coil is proposed. Three-dimension simulation models of the planar-core coil and the pan-shaped coil are established using Ansoft Maxwell software. The coupling coefficient between the transmitting coil and the receiving coil is obtained by simulating the magnetic field with the receiving coil misalignment or not. And the maximum percentage difference strength along the radial direction which is defined as the magnetic field uniformity factor is calculated. According to the simulation results of the two kinds of coil structures, it is found that the new type of coil structure can obviously improve the uniformity of the magnetic field, coupling coefficient and power transmission properties between the transmitting coil and the receiving coil.

The operation strategy for a small-capacity grid-tied DC-coupling power converter interface (GDPCI) integrating wind energy, solar energy and battery energy storage is proposed. The GDPCI is composed of a wind generator, a solar module set a battery bank, a boost DC-DC power converter (DDPC), a bidirectional DDPC power converter, an AC-DC power converter (ADPC) and a five-level DC-AC inverter (DAI). A solar module set, a wind generator and a battery bank are coupled to the common DC bus through the boost DDPC, the ADPC and the bidirectional DDPC, respectively. For verifying the performance of the GDPCI under different operation modes, computer simulation is carried out by PSIM.

In order to study the frequency characteristics of the wireless energy transmission system based on the magnetic coupling resonance, a circuit model based on the magnetic coupling resonant wireless energy transmission system is established. The influence of the load on the frequency characteristics of the wireless power transmission system is analysed. The circuit coupling theory is used to derive the minimum load required to suppress frequency splitting. Simulation and experimental results verify that when the load size is lower than a certain value, the system will appear frequency splitting, increasing the load size can effectively suppress the frequency splitting phenomenon. The power regulation scheme of the wireless charging system based on magnetic coupling resonance is given. This study provides a theoretical basis for load selection and power regulation of wireless power transmission systems.

This paper analyses the relationship between the output power, the transmission efficiency and the frequency, load and coupling coefficient of the four kinds of magnetic coupled resonant wireless charging system topologies. Based on mutual inductance principle, four kinds of circuit models are established, and the expressions of output power and transmission efficiency of different structures are calculated. The difference between the two power characteristics and efficiency characteristics is compared by simulating the SS (series-series) and SP (series-parallel) type wireless charging systems. With the same parameters of circuit components, the SS structure is usually suitable for small load resistance. The SP structure can be applied to large load resistors, when the transmission efficiency of the system is required to keep high. If the operating frequency deviates from the system resonance frequency, the SS type system has higher transmission efficiency than the SP type system.

In the context of current energy Internet, the emergence of a large number of energy productive consumers will create a new business model. In the decentralized electricity market, the cost of traditional centralized solution construction, management and maintenance is too high, and it is difficult to support the collection, transmission, reception, storage and analysis of massive data. To provide a solution to this phenomenon, we apply the blockchain technology to this distributed electricity market to achieve peer to peer transactions in the power systems. The blockchain technology which is very popular nowadays will be used in power system to establish a credible direct transaction between devices. At first, this article analyzes the future direction of the development of power systems, studies the characteristics of decentralized power systems and summarizes the main issues in the development process. Then, we analyze the basic characteristics of blockchain and put forward a new transaction framework in consideration of problems existing in current energy market. The transaction framework is based on the blockchain technology in the distributed electricity market and includes the pricing method, the power transaction system architecture, various modules of the trading system and the details of the whole transaction system runtime. This framework provides a viable solution for increasingly complex energy transactions.

A novel energy management of wind farms is proposed in this paper. Firstly, a novel comprehensive evaluation system is proposed to quantify economic properties of each wind farm to make the energy management more economical and reasonable. Then, a combination of multi time-scale schedule method is proposed to develop a novel energy management. The day-ahead schedule optimizes unit commitment of thermal power generators. The intraday schedule is established to optimize power generation plan for all thermal power generating units, hydroelectric generating sets and wind power plants. At last, the power generation plan can be timely revised in the process of on-line schedule. The paper concludes with simulations conducted on a real provincial integrated energy system in northeast China. Simulation results have validated the proposed model and corresponding solving algorithms.

The air-cooled heat exchanger plays an important role in the field of industry like for example in thermal power plants. On the other hand, it can be used to remove core decay heat out of containment passively in case of a severe accident circumstance. Thus, research on the performance of fins in air-cooled heat exchangers can benefit the optimal design and operation of cooling systems in nuclear power plants. In this study, a CFD (Computational Fluid Dynamic) method is implemented to investigate the effects of inlet velocity, fin spacing and tube pitch on the flow and the heat transfer characteristics of flat fins constructed of various materials (316L stainless steel, copper-nickel alloy and aluminium). A three dimensional geometric model of flat finned tube bundles with fixed longitudinal tube pitch and transverse tube pitch is established. Results for the variation of the average convective heat transfer coefficient with respect to cooling air inlet velocity, fin spacing, tube pitch and fin material are obtained, as well as for the pressure drop of the cooling air passing through finned tube. It is shown that the increase of cooling air inlet velocity results in enhanced average convective heat transfer coefficient and decreasing pressure drop. Both fin spacing and tube pitch engender positive effects on pressure drop and have negative effects on heat transfer characteristics. Concerning the fin material, the heat transfer performance of copper-nickel alloy is superior to 316L stainless steel and inferior to aluminium.

This paper proposes a design steps in sizing of standalone photovoltaic system with hydrogen storage using intuitive method. The main advantage of this method is it uses a direct mathematical approach to find system's size based on daily load consumption and average irradiation data. The keys of system design are to satisfy a pre-determined load requirement and maintain hydrogen storage's state of charge during low solar irradiation period. To test the effectiveness of the proposed method, a case study is conducted using Kuala Lumpur's generated meteorological data and rural area's typical daily load profile of 2.215 kWh. In addition, an economic analysis is performed to appraise the proposed system feasibility. The finding shows that the levelized cost of energy for proposed system is RM 1.98 kWh. However, based on sizing results obtained using a published method with AGM battery as back-up supply, the system cost is lower and more economically viable. The feasibility of PV system with hydrogen storage can be improved if the efficiency of hydrogen storage technologies significantly increases in the future. Hence, a sensitivity analysis is performed to verify the effect of electrolyzer and fuel cell efficiencies towards levelized cost of energy. Efficiencies of electrolyzer and fuel cell available in current market are validated using laboratory's experimental data. This finding is needed to envisage the applicability of photovoltaic system with hydrogen storage as a future power supply source in Malaysia.

The protection is an essential part for power device, especially for those in power grid, as the failure may cost great losses to the society. A study on the voltage and current abnormality in the power electronic devices in Distribution Electronic Power Transformer (D-EPT) during the failures on switching components is presented, as well as the operational principles for 10 kV rectifier, 10 kV/400 V DC-DC converter and 400 V inverter in D-EPT. Derived from the discussion on the effects of voltage and current distortion, the fault characteristics as well as a fault diagnosis method for D-EPT are introduced.

Conservation voltage reduction (CVR) includes peak demand reduction, energy conservation, carbon emission reduction, and electricity bill reduction. This paper analyzes the energy-reduction of Siwei Feeders with applying CVR, which are situated in Penghu region and equipped with smart meters. Furthermore, the applicable voltage reduction range for the feeders will be explored. This study will also investigate how the CVR effect and energy conservation are improved with the voltage control devices integrated. The results of this study can serve as a reference for the Taiwan Power Company to promote and implement voltage reduction and energy conservation techniques. This study is expected to enhance the energy-reduction performance of the Penghu Low Carbon Island Project.

Smart grid has attracted much attention by the requirement of new generation renewable energy. Nowadays, the real-time state estimation, with the help of phasor measurement unit, plays an important role to keep smart grid stable and efficient. However, the limitation of the communication channel is not considered by related work. Considering the familiar limited on-board batteries wireless sensor in smart grid, transmission power schedule is designed in this paper, which minimizes energy consumption with proper EKF filtering performance requirement constrain. Based on the event-triggered estimation theory, the filtering algorithm is also provided to utilize the information contained in the power schedule. Finally, its feasibility and performance is demonstrated using the standard IEEE 39-bus system with phasor measurement units (PMUs).

In co-pyrolysis of biomass-plastics, bio-oil produced contains both oxygenated and non-oxygenated compounds. High oxygen composition is responsible for instability and low heating value of bio-oil and high acid content for corrosiveness. Aims of the present work are to evaluate possibilities of achieving phase separation between oxygenated and non-oxygenated compounds in bio-oil using a proposed stirred tank reactor and to achieve synergistic effects on bio-oil yield and non-oxygenated compound layer yield. Separation of bio-oil into two layers, i.e. that containing oxygenated compounds (polar phase) and non-oxygenated compounds (non-polar phase) is important to obtain pure non-polar phase ready for the next processing of hydrogenation and used directly as bio-fuel. There has been no research work on co-pyrolysis of biomass-plastic considering possibility of phase separation of bio-oil. The present work is proposing a stirred tank reactor for co-pyrolysis with nitrogen injection, which is capable of tailoring co-pyrolysis conditions leading to low viscosity and viscosity asymmetry, which induce phase separation between polar phase and non-polar phase. The proposed reactor is capable of generating synergistic effect on bio-oil and non-polar yields as the composition of PP in feed is more than 25% weight in which non-polar layers contain only alkanes, alkenes, cycloalkanes and cycloalkenes.

Modelling, simulation, optimization and control strategies are used in this study to design a stand-alone solar PV/Fuel Cell/Battery/Generator hybrid power system to serve the electrical load of a commercial building. The main objective is to design an off grid energy system to meet the desired electric load of the commercial building with high renewable fraction, low emissions and low cost of energy. The goal is to manage the energy consumption of the building, reduce the associate cost and to switch from grid-tied fossil fuel power system to an off grid renewable and cleaner power system. Energy audit was performed in this study to determine the energy consumption of the building. Hourly simulations, modelling and optimization were performed to determine the performance and cost of the hybrid power configurations using different control strategies. The results show that the hybrid off grid solar PV/Fuel Cell/Generator/Battery/Inverter power system offers the best performance for the tested system architectures. From the total energy generated from the off grid hybrid power system, 73% is produced from the solar PV, 24% from the fuel cell and 3% from the backup Diesel generator. The produced power is used to meet all the AC load of the building without power shortage (<0.1%). The hybrid power system produces 18.2% excess power that can be used to serve the thermal load of the building. The proposed hybrid power system is sustainable, economically viable and environmentally friendly: High renewable fraction (66.1%), low levelized cost of energy (92 $/MWh), and low carbon dioxide emissions (24 kg CO₂/MWh) are achieved.

Ultrasonic testing technology has been used essentially in non-destructive testing of wind turbine blades. However, it is fact that the ultrasonic flaw detection method has inefficiently employed in recent years. This is because the testing result will illustrate a small deviation due to the artificial, environmental and technical factors. Therefore, it is an urgent technical demand for engineers to test the various flaws efficiently and quickly. An automatic positioning system has been designed in this paper to record the moving coordinates and the target distance in real time. Simultaneously, it could launch and acquire the sonic wave automatically. The ADNS-3080 optoelectronic chip is manufactured by Agilent Technologies Inc, which is also utilized in the system. With the combination of the chip, the power conversion module and the USB transmission module, the collected data can be transmitted from the upper monitor to the hardware that could process and control the data through software programming. An experiment has been designed to prove the reliability of automotive positioning system. The result has been validated by comparing the result collected form LABVIEW and actual plots on Perspex plane, it concludes that the system possesses high accuracy and magnificent meanings in practical engineering.

In this paper, two identical solar driers with the same cross-corrugated solar air collectors and drying chamber were developed, one with phase-change materials (PCMs) and the other without PCMs. These two solar drying systems were tested in typical sunny and cloudy days in Kunming and their thermal performances were analyzed. The experimental results show that the temperature changing is smoother in the collector with the PCMs, which is beneficial for the drying as the useful drying time was prolonged. The same trend was also found in the chamber with the PCMs. The PCMs in solar drying system was found to play a role in temperature regulating. There were several cycles of heat charging-discharging in a cloudy testing day while the temperatures on collectors and in chambers with the polyalcohol PCMs is higher than each phase-change temperature. Nevertheless, there was only one cycle of heat charging-discharging in a sunny testing day. The collector with PCMs has higher daily useful heat gain than the collector without PCMs.

With the seriousness of environmental issues and the shortage of resources, the applicability of green energy technology has been paid more and more attention by scholars in different fields. However, the current researches are often single in perspective and simple in method. According to the Theory of Applicable Technology, this paper analyzes and defines the green energy technology and its applicability from the all-around perspectives of symbiosis of economy, society, environment and science & technology etc., and correspondingly constructs the evaluation index system. The paper further applies the Fuzzy Comprehensive Evaluation to the evaluation of its applicability, discusses in depth the evaluation models and methods, and explains in detail with an example. The author holds that the applicability of green energy technology involves many aspects of economy, society, environment and science & technology and can be evaluated comprehensively by an index system composed of a number of independent indexes. The evaluation is multi-object, multi-factor, multi-level and fuzzy comprehensive, which is undoubtedly correct, effective and feasible by the Fuzzy Comprehensive Evaluation. It is of vital theoretical and practical significance to understand and evaluate comprehensively the applicability of green energy technology for the rational development and utilization of green energy technology and for the better promotion of sustainable development of human and nature.

In this paper, a distributed on-line monitoring system based on a two-level wireless sensor network (WSN) is proposed for real time status monitoring of photovoltaic (PV) arrays to support the fine management and maintenance of PV power plants. The system includes the sensing nodes installed on PV modules (PVM), sensing and routing nodes installed on combiner boxes of PV sub-arrays (PVA), a sink node and a data management centre (DMC) running on a host computer. The first level WSN is implemented by the low-cost wireless transceiver nRF24L01, and it is used to achieve single hop communication between the PVM nodes and their corresponding PVA nodes. The second level WSN is realized by the CC2530 based ZigBee network for multi-hop communication among PVA nodes and the sink node. The PVM nodes are used to monitor the PVM working voltage and backplane temperature, and they send the acquired data to their PVA node via the nRF24L01 based first level WSN. The PVA nodes are used to monitor the array voltage, PV string current and environment irradiance, and they send the acquired and received data to the DMC via the ZigBee based second level WSN. The DMC is designed using the MATLAB GUIDE and MySQL database. Laboratory experiment results show that the system can effectively acquire, display, store and manage the operating and environment parameters of PVA in real time.

The Internet of Things (IoT) Technology is used to inspect photovoltaic (PV) array which can greatly improve the monitoring, performance and maintenance of the PV array. In order to efficiently realize the remote monitoring of PV operating environment, an on-line monitoring system of PV array based on IoT is designed in this paper. The system includes data acquisition, data gateway and PV monitoring centre (PVMC) website. Firstly, the DSP-TMS320F28335 is applied to collect indicators of PV array using sensors, then the data are transmitted to data gateway through ZigBee network. Secondly, the data gateway receives the data from data acquisition part, obtains geographic information via GPS module, and captures the scenes around PV array via USB camera, then uploads them to PVMC website. Finally, the PVMC website based on Laravel framework receives all data from data gateway and displays them with abundant charts. Moreover, a fault diagnosis approach for PV array based on Extreme Learning Machine (ELM) is applied in PVMC. Once fault occurs, a user alert can be sent via E-mail. The designed system enables users to browse the operating conditions of PV array on PVMC website, including electrical, environmental parameters and video. Experimental results show that the presented monitoring system can efficiently real-time monitor the PV array, and the fault diagnosis approach reaches a high accuracy of 97.5%.

In this paper, the topology of a single-phase grid-connected photovoltaic (PV) micro-inverter is proposed. The PV micro-inverter consists of DC-DC stage with high voltage gain boost and DC-AC conversion stage. In the first stage, we apply the active clamp circuit and two voltage multipliers to achieve soft switching technology and high voltage gain. In addition, the flower pollination algorithm (FPA) is employed for the maximum power point tracking (MPPT) in the PV module in this stage. The second stage cascades a H-bridge inverter and LCL filter. To feed high quality sinusoidal power into the grid, the software phase lock, outer voltage loop and inner current loop control method are adopted as the control strategy. The performance of the proposed topology is tested by Matlab/Simulink. A PV module with maximum power 300W and maximum power point voltage 40V is applied as the input source. The simulation results indicate that the proposed topology and the control strategy are feasible.

A novel snake-shape vacuum tube with inserted tubes solar collector is designed in this paper, the heat transfer characteristics of the collector are analyzed according to its structural characteristics, and the influence of different working temperature on thermal characteristics of the collector is studied. The solar water heater prototype consisting of 14 vacuum tubes with inserted tubes is prepared, and the hot water storage control subsystem is designed by hysteresis comparison algorithm. The heat characteristic of the prototype was experimentally studied under hot water output temperature of 40-45°C, 50-55°C and 60-65°C. The daily thermal efficiency was 64%, 50% and 46%, respectively. The experimental results are basically consistent with the theoretical analysis.

We have investigated InGaN-based multi-striped orthogonal photon-photocarrier propagation solar cell (MOP³SC) in which sunlight propagates in a direction being orthogonal to that of photocarriers generated by the sunlight. Thanks to the orthogonality, in MOP³SC, absorption of the sunlight and collection of the photocarriers can be simultaneously and independently optimized with no trade-off. Furthermore, by exploiting the degree of freedom along the photon propagation and using multi-semiconductor stripes in which the incoming photons first encounter the widest gap semiconductor, and the narrowest at last, we can convert the whole solar spectrum into electricity resulting in the high conversion efficiency. For processing MOP³SC, we have developed Clean Unit System Platform (CUSP), which turns out to be able to serve as clean versatile environment having low power-consumption and high cost-performance. CUSP is suitable not only for processing devices, but also for cross-disciplinary fields, including medical/hygienic applications.