Leading edge erosion (LEE) of wind turbine blades causes decreased aerodynamic performance leading to lower power production and revenue and increased operations and maintenance costs. LEE is caused primarily by materials stresses when hydrometeors (rain and hail) impact on rotating blades. The kinetic energy transferred by these impacts is a function of the precipitation intensity, droplet size distributions (DSD), hydrometeor phase and the wind turbine rotational speed which in turn depends on the wind speed at hub-height. Hence, there is a need to better understand the hydrometeor properties and the joint probability distributions of precipitation and wind speeds at prospective and operating wind farms in order to quantify the potential for LEE and the financial efficacy of LEE mitigation measures. However, there are relatively few observational datasets of hydrometeor DSD available for such locations. Here, we analyze six observational datasets from spatially dispersed locations an... [more]

Natural gum derived from the natural surrounding (gum arabic, guar gum, xanthan gum, gellan gum, fenugreek gum, karaya gum, and acacia gum) is one of the most abundant polysaccharides currently present around the world. As natural gum dissolved solution can be very sticky in nature, its role as a binder for both anodes and cathodes in rechargeable batteries have been recently significantly researched. Although much research has been delved into using natural gum as a feasible binder for rechargeable batteries, little investigation so far has taken place to compile, summarize, analyze, and evaluate the current status-quo of the natural gum-based binder research, as well as understanding some of the obstacles and issues that may need to be addressed. This review gives a comprehensive review on the natural gum-based binder that was used for both anode and cathode in rechargeable batteries and how each kind of natural gum improved the electrochemical performance in terms of cycle retention... [more]

Spark-ignited natural gas engines have received increasing attention in the heavy-duty market due to their low cost and reliability advantages. However, there are still some issues with natural gas engines retrofitted from 10 to 15 L diesel engines, which is a valuable medium-term goal for the automotive industry. In this work, the effect of intake port structure on the performance of a spark-ignited heavy-duty natural gas engine was investigated by multidimensional numerical simulations. A newly designed intake port was proposed, with strengthened in-cylinder turbulent kinetic energy and homogeneous air-fuel mixtures. Bench tests show that the proposed intake port has impressive thermal efficiency, cycle variation, and acceptable emissions performance. The effective thermal efficiency improves from 41.0% to 41.4%, and the cycle variation is 36% lower than traditional schemes. However, with the accelerated flame propagation, the in-cylinder temperature and NOx emission of the mixed-flo... [more]

The thermal management system of batteries plays a significant role in the operation of electric vehicles (EVs). The purpose of this study is to survey various parameters enhancing the performance of a heat pipe-based battery thermal management system (HP-BTMS) for cooling the lithium-ion batteries (LIBs), including the ambient temperature, coolant temperature, coolant flow rate, heat generation rate, start-up time, inclination angle of the heat pipe, and length of the condenser/evaporator section. This review provides knowledge on the HP-BTMS that can guarantee achievement of the optimum performance of an EV LIB at a high charge/discharge rate.

The article summarizes the results of the 25-year time horizon performance analysis of the ground source heat pump that serves as a heat source in a detached house in the climatic conditions that prevail in Wrocław, Poland. The main aim is to assess the potential of ground regeneration and reduction of CO2 emission by passive cooling application. The study adds value to similar research conducted worldwide for various conditions. The behavior of the lower source of the heat pump was simulated using EED software. The ground and borehole properties, heat pump characteristics, heating and cooling load, as well as the energy demand for domestic hot water preparation have been used as input data. Based on the brine temperatures for all analyzed cases including the ground with lower and higher values of conductivity and heat capacity, the borehole filler of inferior and superior thermal properties, and the passive cooling option turned on and off, the seasonal efficiencies of the heat pump h... [more]

Today, electricity tariffs play an essential role in the electricity retail market as they are the key factor for the decision-making of end-users. Additionally, tariffs are necessary for increasing competition in the electricity market. They have a great impact on load energy management. Moreover, tariffs are not taken as a fixed approach to expense calculations only but are influenced by many other factors, such as electricity generation, transmission, distribution costs, and governmental taxation. Thus, electricity pricing differs significantly between countries or between regions within a country. Improper tariff calculation methodologies in some areas have led to high-power losses, unnecessary investments, increased operational expenses, and environmental pollution due to the non-use of available sustainable energy resources. Due to the importance of electricity tariffs, the authors of this paper have been inspired to review all electricity tariff designs used worldwide. In this p... [more]

Water scarcity is a global issue recognized by the United Nations under Goal 6 of its Sustainable Development Goals (SDGs), which is to ‘Ensure availability and sustainable management of water and sanitation for all’. This challenging goal requires innovations, especially in areas with freshwater scarcity. Coupling this with the expected significant growth in population, especially in developing countries, presents major challenges to obtaining the appropriate levels of water provision needed. The development of seawater desalination technologies offers hope to alleviate freshwater shortages whilst supporting SDG 6. This research addresses the development of small-scale technology utilizing solar energy for providing clean drinking water in rural, hot, arid, and remote communities. To alleviate water scarcity in rural and isolated areas, a micro solar still (MSS) system that supports a multistage distillation process can be utilized, which evaporates and condenses the saline feed water... [more]

Because the road surfaces of the underground roadways in coal mines are slippery, uneven, with dust and water mist, and the noise and light illumination effects are significant, global positioning system (GPS) signals cannot be received, which seriously affects the ability of the odometer, optical camera and ultrasonic camera to collect data. Therefore, the underground positioning of coal mines is a difficult issue that restricts the intellectualization of underground transportation, especially for automatic robots and automatic driving vehicles. Ultra-wide band (UWB) positioning technology has low power consumption, high performance and good positioning effects in non-visual environments. It is widely used in coal mine underground equipment positioning and information transmission. In view of the above problems, this research uses the WLR-5A mining unmanned wheeled chassis experimental platform; uses two UWB receivers to infer the position and yaw information of the vehicle in the und... [more]

Higher carbon alcohols such as n-propanol, n-butanol, and n-pentanol that can be produced from biomass can be used as alternative fuels in diesel engines. These alcohols can mix with both diesel fuel and biodiesel without any phase separation. Currently, unregulated emissions such as toxicity and total polycyclic aromatic hydrocarbon (PAH) from the use of these alcohols are not monitored. Investigating the effects of increasing the alternative fuel concentration for use in a diesel engine on PAH emissions will contribute to the protection of the environment and extend the engine’s operating life. In this study, the effects of adding 35% (by volume) n-propanol, n-butanol and n-pentanol to diesel and biodiesel on unregulated emissions in a diesel engine were compared. In the total PAH emission of biodiesel, the mixture containing n-pentanol stood out compared to other mixtures with a decrease of 39.17%. In higher alcohol-diesel mixtures, the highest reduction was observed in the n-butano... [more]

Thermal efficiency and power density improvement are the main research foci of the literature on diesel engines. The Miller cycle is considered to be one of the most promising methods of diesel engine operation. In this study, a fully variable valve timing and lift mechanism (CD-HFVVS) was studied to determine the possibility of a Miller operation. Firstly, the valve seat impact buffer in the mechanism was tested, which proved that the buffer can effectively eliminate the valve seat impact. Then the influences of different speeds and oil temperatures were studied. The results show that the valve opening duration is prolonged when engine speed increases, and the valve lift and duration are reduced while the oil temperature increased. The valve timing and lift can be fully adjusted by changing the oil discharge position and the initial plunger position, which further proves that CD-HFVVS can achieve the performance optimization of the Miller cycle. By using the mechanism, a single cylind... [more]

This study reports on the structure analyses of NiO-BCZY (BCZY = BaCe0.54Zr0.36Y0.1O3-δ) anode composite materials with the ratio of 50:50 for proton ceramic fuel cells (PCFCs) application. A product of sintered NiO-BCZY was developed to understand the structural properties of the anode materials. The objectives of this work were (a) to investigate the lattice expansion of the anode by using a high-temperature XRD (HT-XRD) from 400−700 °C; and (b) to calculate the crystallite size of the sample by using Scherrer’s and Williamson Hall’s methods. The results obtained from the HT-XRD revealed that the diffraction peaks of NiO and BCZY are matched with the cubic phase perovskite structure. For example at T = 400 °C, the lattice parameter of NiO is a = 4.2004 Å and BCZY is a = 4.3331 Å. The observation also showed that the lattice expansion increased with the temperature. Furthermore, analyses of the Scherrer and Williamson Hall methods, respectively, showed that the crystallite size is str... [more]

There is a huge requirement for power systems to reduce power losses. Adding distributed generators (DGs) is the most common approach to achieving lower power losses. However, several challenges arise, such as determining the ideal size as well as location of the utilized distributed generators. Most of the existing methods do not consider the variety of load types, the variety and size of the utilized DGs besides reducing the convergence time and enhancing the optimization results. The paper performed an optimization algorithm that integrated a golden search-based flower pollination algorithm and fitness-distance balance (FDB) to find out the optimal size as well as the location of the distributed generators. It was then compared with different optimization methods to determine the best optimization technique, and it was determined to be the best technique. In addition, different types of DGs are considered, including solar energy, wind energy, and biogas, along with optimizing the si... [more]

Compared to mechanical compressors, ejector-based refrigeration systems can make direct use of many forms of thermal energy, including waste heat, solar thermal, or biogases. It is known that SE systems have a lower thermal efficiency compared to mechanical compressors because of their lower performance at high compression ratios. In the present work, binary fluid ejector heat pumps with high efficiency are presented based on a proper selection of the binary fluids and the ejector geometry for specific operating conditions of a ground-source heat pump cooling system (GSHP). The existing literature on ejector-based refrigeration systems considers the thermal COP and does not account for many energy losses across the system. In the present paper, the system COP of an ejector-based GSHP that accounts for all energy exchange processes is determined. A method for the calculation of the work done by the boiler feed pump, the refrigeration expansion valve, and the ground loop circulation pump... [more]

One of the best precursors for winter wheat is fallow. Its application aims to solve two important tasks: preserving and accumulating soil moisture and weed control. The authors of this paper have designed a new modular harrow for fallow tillage, which can work stably at a depth of 5−6 cm tillage while maintaining and even accumulating soil moisture. This article describes a method designed by the authors for a reasonable selection of the design parameters concerning the working devices mounted inside the new harrow, such as their length and working width, as well as the angles of vertical inclination (ε) and horizontal deviation (γ) of blades, depending on the accepted depth of the upper soil layer loosening. To reduce the soil tillage resistance of the harrowing unit resulting in a reduction in the tractor fuel consumption, the value of the inclination angle (ε) of its vertical blade should be chosen so that the corresponding change in the value of the deflection angle of the horizon... [more]

To mitigate the consequences of climate change, there is an increasing need to minimize the usage of fossil fuels, especially in the industrial sector because the majority of the industrial sector primarily rely on fossil fuels to meet their needs for heat energy, and a practical strategy to reduce reliance on fossil fuels is to use energy from the sun. Due to their environmental advantages, energy security, and viability as a potential substitute for fossil fuels, solar thermal collectors are acknowledged as promising technology to harness solar thermal energy fir process heating applications. This review is a thorough compendium and evaluation of contemporary literature on solar thermal collectors and their applications in industry. Apart from applications, this review paper also assesses the challenges and limitations currently hindering the global acceptance of this technology in the industrial sector.

Research over several years has shown that municipal engineering is an important source of humic substance formation (HS). Effluents from municipal landfills and digested sludge, due to high concentrations of organic pollutants, including HS and inorganic pollutants, are discharged to a biological treatment plant, where their largely non-biodegradable pollutants constitute a burden on the activated sludge and generate problems related to wastewater treatment. To demonstrate that humic substances, primarily soluble acids, are the carriers of micro-pollutants, their isolation was carried out from samples taken at different municipal management sites. The following analyses were performed: elemental composition, and the content of inorganic micropollutants, including heavy metals. In addition, the sorption affinity of pure HS to selected pharmaceuticals was investigated. The sorbed pharmaceuticals were Diclofenac and Estrone. HS commonly found in municipal engineering have been shown to b... [more]

With the recent developments in renewable energy generation and addition of power electronic devices, power system dynamics have become extremely complex. One of the challenges faced due to this transition is the sub synchronous oscillations caused by the interaction of renewable energy sources and various components of the power grid. Recently reported incidents due to sub synchronous oscillations highlight the need of monitoring and suppression of these harmful oscillations in real time. This paper gives an overview of the phenomena of sub synchronous oscillations and discusses the existing monitoring and damping techniques along with their limitations. Further, it highlights the research trends along this path.

The deployment of renewable energy (RE) needs to be policy-driven and supported by public funds. Hence, the aim of this study was to find out whether urban and rural areas benefit from public funds for RE deployment equally and whether factors determining other types of investments also determine investments in RES. To do so, we carried out: (i) comparative analyses of qualitative and quantitative data describing 2642 investments in solar RE supported by the European Union funds and carried out in Poland under operational programmes in 2014−2020; (ii) multiple linear regressions, evaluating the predictions. Findings showed that principles of supporting solar RE investments were the same for all kinds of beneficiaries in both urban and rural areas. However, in rural areas, most RE investments cumulated in eastern, north-eastern and south-eastern parts of Poland, and depended only on few socio-economic characteristics. RE investments in urban areas were dispersed all over the country rat... [more]

A thermoelectric effect occurs when a material’s intrinsic property directly converts temperature differences applied across its body into electric voltage. This manuscript presents the prediction for maximum and optimal heat transfer efficiency of a thermoelectric fluid via the non-classical approach of the differential operator. The fractionalized mathematical model is also established to analyze the efficiency and characteristics of thermoelectric fluid through a temperature distribution and velocity field. The comprehensive analytical approach of integral transforms and Cardano’s method are applied to provide analytical solutions that include the dynamic investigation of the temperature distribution and velocity field. A dynamic investigation of the temperature distribution and velocity field of the thermoelectric fluid is explored on the basis of magnetization and anti-magnetization, which describe the behavior for sine and cosine sinusoidal waves. The rheological parameter, i.e.,... [more]

Rising wind energy integration, accompanied by a decreasing level of system inertia, requires additional sources of ancillary services. Wind turbines based on doubly fed induction generators (DFIGs) can provide inertial and primary frequency support when equipped with specific controls. This paper investigates the effect of frequency support provision by DFIGs on the small-signal stability of power systems. To this end, a modified version of the Kundur two-area test system is employed to analyze different scenarios. Wind energy generation is either added to the existing system or displaces part of the synchronous generation. Simulations show that primary frequency support tends to improve the damping of electromechanical oscillations and deteriorate it for converter control-based ones. On the other hand, the inertial response depends on the control parameters.

For the high performance of a fuel cell where a bipolar plate (BP) is applied, rectangular channel, microchannel width, micro-rib, enough channel quantity, adequate channel depth, and innovative flow field design should be realized from a configuration standpoint. In this study, a stainless-steel BP with a microchannel flow field is fabricated with a powder bed fusion (PBF) 3D printer to improve fuel cell performance. A BP with a triple serpentine flow field, rectangular channel, 300 μm channel width, 300 μm rib, and 500 μm channel depth is designed. The print is completed perfectly until the flow field. The bending phenomenon due to thermal deformation does not occur in the BP fabricated by designing the thickness at 2 mm. Performance tests are conducted using fabricated stainless-steel BPs. The current density value is 1.2052 A/cm2 at 0.6 V. This value is higher by 52.8% than the BP with 940 μm channels (rectangle, 940 μm ribs, and 500 μm channel depth). In addition, the value is hig... [more]

As clean and low-carbon energy, wind energy has attracted the attention of many countries. The main bearing in the transmission system of large-scale wind turbines (WTs) is the most important part. The research on the condition monitoring of the main bearing has received more attention from many scholars and the wind industry, and it has become a hot research topic. The existing research on the condition monitoring of the main bearing has the following drawbacks: (1) the existing research assigns the same weight to each condition parameter variable, and the model extracts features indiscriminately; (2) different historical time points of the condition parameter variable are given the same weight, and the influence degree of different historical time points on the current value is not considered; and (3) the existing literature does not consider the operating characteristics of WTs. Different operating conditions have different control strategies, which also determine which condition pa... [more]

Natural gas is a fossil fuel that has been widely used for various purposes, including residential and industrial applications. The combustion of natural gas, despite being more environmentally friendly than other fossil fuels such as petroleum, yields significant amounts of greenhouse gas emissions. Therefore, the optimization of natural gas consumption is a vital process in order to ensure that emission targets are met worldwide. Regarding residential consumption, advancements in terms of boiler technology, such as the usage of condensing boilers, have played a significant role in moving towards this direction. On top of that, the emergence of technologies such as smart homes, Internet of Things, and artificial intelligence provides opportunities for the development of automated optimization solutions, which can utilize data acquired from the boiler and various sensors in real-time, implement consumption forecasting methodologies, and accordingly provide control instructions in order... [more]

Multiple faults in new energy vehicle batteries can be diagnosed using voltage. To find voltage fault information in advance and reduce battery safety risk, a state-partitioned voltage fault prognosis method based on the self-attention network is proposed. The voltage data are divided into three parts with typical characteristics according to the charging voltage curve trends under different charge states. Subsequently, a voltage prediction model based on the self-attention network is trained separately with each part of the data. The voltage fault prognosis is realized using the threshold method. The effectiveness of the method is verified using real operating data of electric vehicles (EVs). The effects of different batch sizes and window sizes on model training are analyzed, and the optimized hyperparameters are used to train the voltage prediction model. The average error of predicted voltage is less than 2 mV. Finally, the superiority and robustness of the method are verified.

Two-phase flow in non-circular cross-section flow channels such as micro-heat sinks and micro-channel heat exchangers has received extensive attention due to its heat-enhancing properties. In this paper, under the boundary of constant heat flux, an experimental investigation of the heat transfer properties of gas−liquid two-phase flow in horizontal channels with cross-sections of 4 × 4 mm and 8 × 3 mm is carried out using air and water as working fluids. The effects of different inlet gas and liquid inlet Reynolds numbers on the wall temperature and Nusselt number are discussed. The results show that the effects of the liquid Reynolds number and the gas phase Reynolds number on the heat transfer coefficient of the square tube and the rectangular tube are different. Under the same gas−liquid Reynolds number, the Nusselt number of the gas−liquid two-phase flow in the square-section tube can be increased by 3.2 times compared with that in the single-phase flow, while the Nusselt number of... [more]