For more than 20 years, the use of nanofluids to enhance heat transfer in microchannel heat sinks (MCHSs) has been the subject of a large number of scientific articles. Despite the great potentialities reported in several works, the presence of controversial results and the lack of understanding of heat transfer enhancement mechanisms prevent further advancement in the use of nanofluids as coolants. This article reviews the scientific literature focused on several aspects of nanofluids that have a role in the heat transfer enhancement within the MCHSs: nanofluid stability, thermal conductivity, and particle clustering, as well as the particle−surface interactions, i.e., abrasion, erosion, and corrosion. We also include the most relevant works on the convective heat transfer and MCHSs operated with nanofluids in our review.

An economic analysis of the implementation of the power-to-gas (PtG) system between 2030 and 2055 is presented at a large scale. The capacity of the PtG system is adapted to two scenarios in Spain (Bailera and Lisbona 2018), corresponding to growing scenarios of 1.73 and 1.36%/y of its electricity market. The total power capacity of the PtG system has been fixed to 12.7 and 3.84 GW, respectively, at the end of 2055. The levelized cost of storage (LCOS) of the implementation of PtG has been evaluated. Assuming uncertainties in the current cost projections for CAPEX and OPEX, LCOS estimations are between 136 and 686 EUR/MWh with a payback time of 16 years in the best scenario for a reference electricity purchase of 100 EUR/MWh and a CO2 penalty of 100 EUR/ton. A sensitivity analysis and the viability dependence versus energy purchase and CO2 penalty certificates is shown. This work sheds some light for the comparison of PtG implementation costs in comparison with other storage options, s... [more]

The shale gas exploration of the Longmaxi Formation in the Yangtze Region of China has made a significant breakthrough. As an important hydrocarbon generation organism, graptolite is widely distributed in the Longmaxi Formation shales, but its hydrocarbon potential is still unclear. Taking the Longmaxi Formation shales in the Middle Yangtze Region as an example, this paper discusses the organic petrological characteristics of graptolite and its contribution to buried organic carbon. The Longmaxi shales in the study area can be divided into organic-rich shales (TOC > 2.0%) and organic-bearing shales (TOC < 2.0%). The organic-rich shales have high quartz content and low clay mineral content, which is opposite in the organic-bearing shales. Organic maceral results show that graptolite is widely distributed in nearly all the samples, while solid bitumen is relatively developed in organic-rich shale. The equivalent vitrinite reflectance obtained from the conversion of graptolite reflecta... [more]

This study examines the relationships between information and communication technology (ICT) usage and CO2 emissions considering economic growth, trade openness, and renewable electricity in the Organization for Economic Co-operation and Development countries for the period 1990−2018. It adopts pooled mean group (PMG) estimation based on the autoregressive distributed lag model. The PMG estimates indicate that although the coefficient value is small, ICT progress acts as a factor in increasing CO2 emissions in the long run. However, there is no significant short-run relationship between these two variables. Furthermore, economic growth increases CO2 emissions in the short and long run. The expansion of renewable electricity and trade openness reduces CO2 emissions in the long run. To mitigate the CO2 emissions originating from ICT, energy-saving technologies that use ICT as an energy management system should be further enhanced. The expansion of renewable electricity and the promotion... [more]

For safety issues in lithium-ion batteries (LIBs), international standards and regulations for various abusive environments have been developed, and UL1642 in Underwriters Laboratories (UL) currently covers electrical, mechanical, environmental, and fire exposure tests. An impact test is one of mechanical abuse tests in UL1642, which aims to determine the safe prevention of fire or explosion. As the energy density of a lithium-ion battery is continuously increasing, it is difficult to pass the regulation. Therefore, it is necessary to predict failure mode due to an internal short circuit in developing high-capacity cells. For a sudden and measured mechanical force, we speculate that damage to a separator consisting of LIBs makes the battery experience an exothermic phenomenon due to an internal short circuit because a separator is a key component for preventing the electrical contact between two electrodes. Therefore, if we can find mechanical stresses of each component in LIBs, we can... [more]

Concentrating solar thermal (CST) systems are unique among renewable energy options for the ease of integration with thermal energy storage (TES). This enables dispatchable (or continuous) production of electricity, process heat, solar fuels, or other chemical products. The solar receiver in a CST system converts concentrated sunlight to transportable thermal energy. In solar power towers, the solar receiver’s physical limitations are often the constraining conditions for the system; they restrict maximum temperature, maximum solar concentration, or controllable chemical production. It is also a uniquely challenging component to prototype and test at sizes beyond the laboratory scale. Transitioning exceptional research innovations into viable components for an integrated system and ultimately leading to CST market adoption requires a multiscale vision for component de-risking and development. Technical requirements for holistic novel receiver development are reviewed based on learnings... [more]

Traditional power grids are mainly based on centralized power generation and subsequent distribution. The increasing penetration of distributed renewable energy sources and the growing number of electrical loads is creating difficulties in balancing supply and demand and threatens the secure and efficient operation of power grids. At the same time, households hold an increasing amount of flexibility, which can be exploited by demand-side management to decrease customer cost and support grid operation. Compared to the collection of individual flexibilities, aggregation reduces optimization complexity, protects households’ privacy, and lowers the communication effort. In mathematical terms, each flexibility is modeled by a set of power profiles, and the aggregated flexibility is modeled by the Minkowski sum of individual flexibilities. As the exact Minkowski sum calculation is generally computationally prohibitive, various approximations can be found in the literature. The main contribut... [more]

This book covers research relating to advanced analytics in renewable energy and shows how to apply these analytics to many different professional areas, including engineering and management [...]

Accurately predicting the remaining useful life (RUL) of lithium-ion batteries (LIBs) is important for electronic equipment. A new algorithm is proposed to aim at the nonlinear degradation caused by capacity regeneration and random fluctuations. Firstly, the health state degradation curve of LIBs is divided into the normal degradation trend part, capacity regeneration part, and random fluctuation part. Secondly, the capacity degradation curve of LIBs is decomposed by the empirical mode decomposition (EMD) to obtain the known long-term degradation trend part of LIBs. Then, the long short-term memory (LSTM) neural network is used to predict the future normal degradation trend part based on the known long-term degradation trend part of LIBs. In addition, the LIBs’ state of health (SOH), the initial state of charge (SOC), and the rest time are taken as the inputs of Gaussian process regression (GPR) to predict the LIBs’ capacity regeneration part. After that, random numbers obeying the Sta... [more]

Achieving net-zero carbon in the UK by 2050 will necessitate the decarbonisation of the transportation systems. However, there are challenges to this, especially for vehicles in cities where the charging infrastructure is at its minimum. Overcoming these challenges will undoubtedly encourage electrical vehicle (EV) use, with commensurate reductions in emission coupled with better environmental conditions in cities, e.g., air quality. Drivers, on the whole, are reluctant to invest in an EV if they cannot access a convenient charging point within their living area. This research provides a methodology to support the planning for the optimum siting of charging infrastructure, so it is accessible to as many citizens as possible within a city. The work focuses on Winchester City and District in the UK. The multi-criteria decision approach is based on the Analytical Hierarchy Process (AHP) linked to site spatial assessment using Geographical Information System (GIS). The assessment considere... [more]

The underground coal gasification (UCG) technology is an unconventional method of coal mining, and its approaches represent new scientific knowledge [...]

This paper proposes a shielding sensor (SS) coil to solve the misalignment issue and the leakage magnetic field issue of the wireless power transfer (WPT) system for electric vehicles (EVs). The misalignment issue and leakage magnetic field issue must be solved because they can cause problems with power transfer efficiency reduction and electronic device malfunction. To solve these problems, the proposed SS coils are located over the Tx coil. The newly created mutual inductance between the Tx coil and the SS coil is used to detect the misalignment of the receiver in the Tx coil. In addition, the current phase of the SS coil is adjusted through impedance control of the SS coil to reduce the leakage magnetic field. The proposed SS coils were applied to the standard SAE J2954 model for the wireless charging of an EV. The WPT3/Z2 model of SAE J2954 with output power of 10 kW was simulated to compare the shielding effect according to the power transfer efficiency, and it was confirmed that... [more]

The current investigation shows a possible new pathway for more efficient and cost-effective energy-harvesting photovoltaic devices. Our approach could permit all emerging technologies that are currently used for indoors and smart buildings to go a step forward and could be used for outdoor applications. The investigated architecture is a very promising geometry especially for Dye-Sensitized Solar Cells (DSSCs). It turns their main drawback, the lowering of their efficiency and lifetime when operating at high solar irradiation density, into an asset by increasing the total active area per horizontal unit area for light harvesting, while preserving the active elements from degradation and extending durable lifetime. The investigated architecture is based on a symmetric “U” type geometry, which is constructed by a highly reflective material on the inner surface. Solar irradiation is reflected internally at the bottom of the construction and splits towards two opposite sided solar cells;... [more]

With the increasing focus on renewable energy, there is a need to improve the efficiency of vertical-axis wind turbines (VAWTs). The Ugrinsky wind turbine is a type of VAWT, but there are few studies on this turbine. Previous studies have shown that the maximum power coefficient of the Ugrinsky wind turbine reaches 0.170, which is 54.5% higher than that of the Savonius type (0.110), and this turbine maintains a high power coefficient over a wide range of tip speed ratios (TSR). In this study, the dimensions of the two semicircles of the Ugrinsky wind turbine were further optimized to obtain a higher power coefficient. An analysis of the effect of the blade dimensions on the performance was conducted. The flow around the turbine was simulated using the regularized lattice Boltzmann method. The geometry of the turbine was simulated using the virtual flux method for the Cartesian grid. The optimization was conducted in terms of the output power coefficient and the average value of the pow... [more]

The Young’s modulus and Poisson’s ratio, parameters reflecting the elastic response of a rock to stress, are the key parameters used in many engineering activities, such as hard coal mining and natural gas extraction. The objective of this paper was to present the results of complex laboratory measurements of the static and dynamic Young’s modulus and Poisson’s ratio for Upper Carboniferous hard coals from the Upper Silesian Coal Basin. The coals differed in geologic age (Mudstone Series—younger coals; Upper Silesian Sandstone Series—older coals) and petrographic structure (vitrain, clarain, and durain lithotype). Elastic parameters of the coals were determined following compression tests under a complex state of stress, as well as using the ultrasonic method in reservoir conditions. On this basis, linear functional dependences between parameters such as UCS, differential stress, confining pressure, strain rate, P- and S-wave velocities, and the static and dynamic Young’s modulus and P... [more]

One of the most important measures taken in reducing the impact of climate change resulting from global warming is the production of energy from clean and renewable resources. Hydroelectric power plants are leading renewable energy sources. In this study, the effects of climate change on hydroelectric power plants, a renewable energy source, have been investigated. Dogancay I and II Hydroelectric Power Plants, which are built on the Sakarya River located in the Sakarya basin of Turkey, was selected as a study area. Moreover, the monthly average energy, runoff, and efficiency parameters of hydroelectric power plants and the monthly average precipitation, temperature, and humidity physical parameters of the Sakarya province, which is a working area, were considered. The length of time-series data is 48 months (2015−2018). Analysis of the data was performed with the innovative polygon trend analysis (IPTA) method, which is one of the newest trend analysis methods. When the studies in the... [more]

In this paper, the 3-D squeezing flow of viscous incompressible fluid between two parallel plates rotating at the same rate is investigated. The flow is observed under the influence of the varying magnetic field. The flow phenomena are modeled by utilizing the basic governing equations, i.e., equation of continuity, coupled Navier Stokes, and Magnetic Field equations. Using appropriate similarity transformations, the resultant partial differential equations are then transformed into a system of ordinary differential equations. The computational technique is developed via the Homotopy Analysis Method (HAM) to obtain the solution of transformed systems of ordinary differential equations. The influence of several engineering fluid parameters, such as squeeze Reynolds number, magnetic field strength parameter, and magnetic Reynolds number, on velocity and magnetic field components, are observed from different graphs. It has been investigated that by increasing the squeeze Reynolds number,... [more]

The economic crisis caused by the COVID-19 pandemic reinforces the problem of rising electricity prices, which mainly affects countries that are forced to pay ever-higher CO₂ emission allowance fees (e.g., Poland). In the light of signals confirming the need for intensive development of the wind energy market in the Baltic Sea region, the authors consider the need to examine this issue concerning Poland and the Baltic States (i.e., Lithuania, Latvia and Estonia) as extremely important and demanding. The development of the RES market is currently an absolute necessity. The immediate neighbourhood and similar general social and economic conditions of Poland and the Baltic States enable factual comparisons, reinforcing the rationale for choosing the adopted research area. The main objective of the study was to assess the development of the wind energy market in Poland in the background of the Baltic Sea bordering countries in the era of the COVID-19 pandemic, in order to try to answer the... [more]

Consumers are always influenced by external information before making decisions to purchase energy-saving electric appliances. However, the effects of different information sources are overlooked by previous studies. As a kind of green and safe appliance, the Heat Pump Water Heater (HPWH) is expected to be popular in the Chinese market. This study, based on an investigation in eastern China, will reveal the attitudes of potential consumers to HPWHs and verify the effects of different information sources. The results show that official information (Information from enterprises and governments) can arouse consumers’ positive attitudes toward HPWHs, yet can significantly reduce perceived usefulness among consumers, while unofficial information (Information from relatives and friends) negatively affects their attitudes. Although HPWHs are billed as energy-saving and eco-friendly appliances, consumers can obtain different information from online or offline interpersonal communications to ob... [more]

Insufficient rainfall in the dry season and scarcity of surface water has resulted in firms’ reliance on groundwater for agriculture in the northern part of Bangladesh. Most irrigation systems in the country are diesel or electric, which raises the cost and demand for energy and pollutes the environment. Utilizing the abundant sunshine and disseminating solar-based irrigation systems is expected to be a fittingly rewarding experience for irrigation purposes. Therefore, this study identifies the factors influencing the adoption of solar irrigation facilities (SIFs) and the impacts of their adoption on irrigation cost, return on investment (ROI), and production costs, using survey data collected from 405 rice farmers of Dinajpur district. The study employed three treatment effect estimators, namely inverse probability weighting (IPW), regression adjustment (RA), and inverse probability weighted regression adjustment (IPWRA), to address the potential selection bias issue. The results reve... [more]

Glucose, sucrose, D(+)-xylose and α-lactose monohydrate are selected as additives relative to the negative electrolyte of Vanadium Redox Flow Battery (VRFB), with the aim of reducing vanadium permeation and improving electrochemical performance to mitigate capacity decay. The results of a charge−discharge test show that the cell with α-Lactose monohydrate in the negative electrolyte exhibits the best capacity retention. The capacity retention of a single cell employing 1 wt% α-Lactose monohydrate in the negative electrolyte was 71% after 30 cycles, which is 41.5% higher than 29.5% of the control group. Correspondingly, adding α-Lactose monohydrate into the negative electrolyte also significantly inhibits vanadium crossover and water transfer. Furthermore, the effects of additives on the performance of the negative electrolyte are studied by thermal stability experiments, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The stability experiments indicate that th... [more]

The current study employs a Granger causality test within a Quantile approach investigating CO2 emission determinants in China. Results show urbanization, financial development and openness to trade are leading determinants of CO2 emissions in China. These results highlight climate change issues while taking advantage of a new methodology to fill a gap in the current literature. Our findings show key implications for PRC government policy related to pollutant reduction policy.

The market for eco-friendly batteries is increasing owing to population growth, environmental pollution, and energy crises. The widespread application of lithium-ion batteries necessitates their state of health (SOH) estimation, which is a popular and difficult area of research. In general, the capacity of a battery is selected as a direct health factor to characterize the degradation state of the battery’s SOH. However, it is difficult to directly measure the actual capacity of a battery. Therefore, this study extracted three features from the current, voltage, and internal resistance of a lithium-ion battery during its charging−discharging process to estimate its SOH. A battery-accelerated aging test system was designed to obtain time series battery degradation data. A performance comparison of lithium-ion battery SOH fitting results was conducted for two different deep learning architectures, a long short-term memory (LSTM) network and temporal convolution network (TCN), which are t... [more]

Vehicle-to-grid (V2G) has been identified as a key technology to help reduce carbon emissions from the transport and energy sectors. However, the benefits of this technology are best achieved when multiple variables are considered in the process of charging and discharging an electric vehicle. These variables include vehicle behaviour, building energy demand, renewable energy generation, and grid carbon intensity. It is expected that the transition to electric mobility will add pressure to the energy grid. Using the batteries of electric vehicles as energy storage to send energy back to the grid during high-demand, carbon-intensive periods will help to reduce the impact of introducing electric vehicles and minimise carbon emissions of the system. In this paper, the authors present a method and propose a V2G control scheme integrating one year of historical vehicle and energy datasets, aiming towards carbon emissions reduction through increased local consumption of renewable energy, off... [more]

The hydrostatic bearing is the core component of ultra-precision computer numerical control (CNC) machine tools. Because the temperature rise in the oil film of hydrostatic bearings seriously affects the working accuracy of the bearings, it is important to study the flow and heat transfer characteristics of the oil film. Based on the physical model of an incompressible viscous fluid flowing in a flat microfluidic boundary layer, velocity, temperature and heat flux distribution equations of oil film are constructed by theories of heat transfer and hydrodynamics. Then, the effects of several parameters on velocity distribution, temperature distribution and heat flux distribution are analyzed, such as the upper plate velocity, the channel length, and so on. The results show that the dimensionless velocity of the oil film decreases with the increase in the upper plate velocity and the channel length. The oil film temperature distribution can be divided into three zones: the increasing zone... [more]