During methane extraction, the permeability of a coal seam is the vital factor affecting recovery. Although the permeability of a coal seam and its relationship with porosity have been studied in a few works, the calculation process of coal seam permeability is usually too simplistic or neglects the influence of microscopic fracture structures. Statistical research shows that the permeability of coal seams with the same porosity and different fracture structures is quite different. For the purpose of quantitatively investigating the contribution of fractures and pore structure in coal seams, a fractal permeability model considering the microstructure of coal seam fracture is established in this paper. The correctness of the model is verified by comparing with the previous research results. Then, the influence of the microscopic fracture structure on the equivalent permeability is analyzed. The simulation results show that the permeability of fractured coal is directly proportional to t... [more]

Driven by the global campaign against the dual pressures of environmental pollution and resource exhaustion, the Chinese government has proposed the target of carbon neutrality. On account of this, the increasing number of waste lithium-ion batteries (LIBs) from electric vehicles (EVs) is causing emergent waste-management challenges and it is urgent that we implement an appropriate waste-LIB recycling program, which would bring significant environmental benefits. In order to comprehensively estimate the total greenhouse gas (GHG) emissions from waste-LIB recycling, the GHG savings also need to be taken into account. Based on the requirements of a carbon-neutral target, this study adopted the Intergovernmental Panel on Climate Change (IPCC) method to established a mathematical model for measuring the GHG emissions and GHG savings of waste LIBs and a numerical experiment is presented to verify the model. The results were analyzed and are discussed as follows: (1) To achieve carbon neutra... [more]

As marine renewable resources begin to become a feasible energy source, it becomes crucial to investigate the nearshore impact of hydrodynamic and morphodynamic processes. As part of the implementation of turbines in the numerical modeling environment of Telemac-3D and Sisyphe modules, we conducted a 10-year run to evaluate nearshore impacts of turbines in the flow. We used five criteria to define viable locations. Turbines sites were added to a conversion energy model coupled into the hydrodynamic model in order to develop properly the flow changes towards the energy conversion process. The results revealed that in the three chosen spots, turbines were not converting equally the current energy within the site. In fact, the turbines located on the outer side of the farm developed greater conversion rates. This impacted the nearshore in the following ways: (1) the decrease in the currents intensity that generates strong adjustments in the water column, breaking the natural pattern of ve... [more]

A one-dimensional (1D) simulation calculation model was created using GT-Power software to investigate the effect of an exhaust gas recirculation (EGR) in concert with the Miller cycle on engine fuel economy and using a 1.5 T gasoline direct injection (GDI) engine as the source engine. The engine was tested under partial loading, full loading, and declared working conditions. The results show that under partial load, the Miller cycle could improve engine fuel economy by reducing pumping losses. In the low-speed 1000 r/min full load region, the Miller cycle had a significant effect on increasing the engine fuel economy. When the Miller intensity was −29 °CA, the fuel consumption decreased by a maximum of 10.5%. At medium speeds, 2000 r/min to 3600 r/min, the Miller cycle did not improve fuel economy significantly. For the Miller cycle with late intake valve closure (LIVC), when the EGR rate was about 7%, the fuel consumption was reduced by about 1.3% compared with the original engine at... [more]

Engine development needs to reduce costs and time. As the current main development methods, 1D simulation has the limitations of low accuracy, and 3D simulation is a long, time-consuming task. Therefore, this study aims to verify the applicability of the machine learning (ML) method in the prediction of engine efficiency and emission performance. The support vector regression (SVR) algorithm was chosen for this paper. By the selection of kernel functions and hyperparameters sets, the relationship between the operation parameters of a spark-ignition (SI) engine and its economic and emissions characteristics was established. The trained SVR algorithm can predict fuel consumption rate, unburned hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions. The determination coefficient (R2) of experimental measured data and model predictions was close to 1, and the root-mean-squared error (RMSE) is close to zero. Additionally, the SVR model captured the corresponding trend of... [more]

Co-gasification of coal and biomass is an important way to reduce the consumption of fossil fuels and achieve the efficient utilization of biomass resources. Two kinds of biomass containing corn straw (CS) and poplar sawdust (PS) were blended with different coal. Then, the coal char was separated from the blended char after co-pyrolysis based on the difference in particle size. The structural properties, including alkali and alkaline earth metals (AAEMs), microcrystalline structures, and molecular structures of the char samples were analyzed. Gasification reactivity of the char was determined by thermogravimetric analyzer (TGA). Results indicated that K and Mg contents in biomass evaporated easily and deposited on coal char, resulting in the increase in those in coal char during co-pyrolysis, and then the AAEMs contents in coal char were determined by the AAEM species and contents in biomass. Meanwhile, the inhibition effect on the graphitization degree of coal char increased with incr... [more]

Driven by energy shortages and climate concerns, the electric vehicles are popular around the world with their energy-saving and environmentally friendly advantages. As electric vehicle batteries (EVBs) mainly use lithium batteries, and the batteries’ performance decreases with the increase of charging times, a large number of batteries are entering the end-of-life (EoL) stage. Recycling and reuse of EVBs are effective ways to reduce environmental pollution and promote resources utilization and is now a top priority. Building a recycling network is the foundation of battery recycling. However, there are few studies on battery recycling networks and the construction of recycling networks is expensive, which impedes the sustainable development of electric vehicles. Based on this, recycling network design is critical for EVB recycling. This paper first analyzes three strategies to deal with used batteries: remanufacturing, reuse, and recycling materials. Secondly, an EVB recycling network... [more]

The vanadium redox flow battery (VRFB) is a promising and commercially available technology that poses advantageous features for stationary energy storage. A key component of the VRFB in terms of cost and system efficiency is the membrane. In recent years, anion exchange membranes (AEMs) have gained interest in VRFB research as they in general exhibit lower vanadium crossover due to a more substantial Donnan exclusion effect. In this study, a low-resistance flow cell was developed and the electrochemical performance of Aemion™ anion exchange membranes AF1-HNN5-50-X, AF1-HNN8-50-X and AF1-ENN8-50-X were compared against commonly used cation exchange membranes, Nafion® 211 and 212. The VRFB using AF1-ENN8-50-X exhibited superior performance versus Nafion® 212 regarding cycling efficiency and rate performance. However, relatively high and comparable capacity losses were observed using both membranes. NMR analysis showed no sign of chemical degradation for AF1-ENN8-50-X by immersion in VO2... [more]

Improving the efficiency of coal-fired boiler is beneficial for greenhouse gas control, mainly for carbon dioxide (CO2). The low-temperature corrosion covering heating surfaces is a frequent threat for coal-fired thermal equipment. The corrosion is induced by a fouling layer, where the ash deposition and condensed acid in coal-fired flue gas react mutually. The corrosion experiments were designed to investigate the reactions of representative acid solution between basic oxides, non-basic oxides, and fly ash particles covering metal surfaces. Scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), X-ray fluorescence (XRF) and X-ray diffraction (XRD) were used to analyze the reaction particles and metal samples collected from experiments. The corrosion rates of 316L steel, 20# steel, Corten steel and ND (09CrCuSb) steel by the sulfuric solution of different concentrations with and without particles were obtained. The results showed that corrosion rate... [more]

R134a is currently the most widely used refrigerant, whose problem is the high value of the global warming potential, and which will have to be replaced in the near future. Thus far, R1234ze(E) has proven to be the most suitable alternative, but it is slightly flammable. Recently, R1336mzz(E) has emerged as a possible alternative. During the research, the mentioned refrigerants were compared with simulations using the Aspen Plus software package in the case of using groundwater as a heat source. It was found that R1336mzz(E) could be a suitable alternative to R134a since the highest value of coefficient of performance was obtained using it. However, it must be superheated with an internal heat exchanger. The problem with using an internal heat exchanger is that the superheating of the refrigerant vapors affects the isentropic efficiency of the heat pump compressor negatively and, consequently, lowers the COP value of the heat pump. It has been shown that a one percent decrease in isent... [more]

The financial evaluation of renewable energy sources (RES) projects is well explored in the literature, but many different methods have been followed by different authors. Then, it is important to understand if and how these methods have been changing and what factors may have driven new approaches. Therefore, this article aims to explore the publications on the financial evaluation of RES projects from 2011 to 2020 and to present a critical analysis of the reviewed literature. The methods for evaluating RES projects were grouped into four categories: (i) traditional metrics based on net present value, internal rate of return, and payback period; (ii) levelized cost of electricity; (iii) return on investment approach; and (iv) real options analysis. A quantitative analysis was carried out considering aspects related to the relevance of the authors, productivity by country, and the most relevant journals for each of these groups. Then, a qualitative analysis of the main characteristics... [more]

The present study aimed at investigating the use of a drying system combining the concept of low-pressure superheated steam drying and heat pump drying for fish. The effects of various drying medium pressures on the temperature field, airflow field, drying time, equipment performance as well as the power consumption of the drying process were investigated and discussed. Four comparative tests with different initial pressures were carried out according to a specified drying process by the combined drying system. The results showed that when the vacuum was high, the temperature field and airflow field in the drying chamber were more uniform. Due to the poor heat transfer performance of the drying medium at high vacuum, the drying time increased with a decrease in initial pressure. It was also found that with the decrease in drying medium pressure, the power consumption of the heat pump and the axial fans was reduced, while the power consumption of the electric heater went up. Overall, th... [more]

The effect of Brown’s gas on the gas-phase tar cracking behavior, carbonic oxide (CO) production rate, and gaseous product temperature during the pine wood pyrolysis was preliminarily explored. By the application of cold trapping and gravimetric methods, it was found that Brown’s gas reduces the energy barrier of thermochemical conversion for gas-phase tar, widens the temperature range of gas-phase tar accelerated cracking, and increases the cracking rate. When the pyrolysis temperature increases by 1 °C, the average cracking rate of gas-phase tar increases from C = 4.58 g⋅Nm−3 (flow volume ratio of Brown’s gas to nitrogen, X(Brown’s gas):N2 = 0%) to C = 4.8 g⋅Nm−3 (X:N2 = 1%) and C = 5.02 g⋅Nm−3 (X:N2 = 5%). While participating in the deep cracking of gas-phase tar, Brown’s gas reduces the conversion energy barrier of the gas-phase tar to CO. The CO production rate rises from the initial 1.87% (X:N2 = 0%) to 4.22% (X:N2 = 1%) and 5.52% (X:N2 = 5%) per 1 °C of increased pyrolysis tempe... [more]

The novel modified absorption heat pump (MAHP) with the H2O-LiBr working mixture for cogeneration applications is introduced. The MAHP can simultaneously produce electric energy and heat revaluation. The proposed system has the particularity that it can be powered by alternative thermal sources (such as solar energy, biomass, geothermal) or industrial waste heat, thus promoting the production and efficient use of clean energy. The effects of pressure ratio (RP), source or supply temperature (TGH), and the energy revaluation gradient (GTL) are analyzed. The critical parameters of the proposed system are evaluated, including thermal efficiency (ηTh), exergetic efficiency (ηEx), revaluated heat (Q˙A), as well as net power produced (˙Wnet). For the MAHP analysis, RP and TGH operating ranges were chosen at 1.1−15.0 and 100−160 °C, respectively. The results show that ηEx of 87% can be obtained, having the maximum performance in TGH of 120 °C, RP of 1.1, and GTL of 35 °C. The ηTh varies betwe... [more]

Two once-through steam generators and a combination of a steam generator and a gas preheater for supplying feed gases to solid-oxide electrolysis stacks were evaluated for their carryover characteristics of contaminants from the feed-water into the steam phase. The concentrations of various trace impurities in the steam were determined by sampling the steam condensates and screening them with inductively coupled plasma−mass spectrometry for 19 elements and liquid ion chromatography and continuous flow analysis for chloride and ammonium. Steam-soluble species such as boric acid undergo complete volatilization and transfer into the steam phase. During unstable evaporation in the steam generators an extensive physical carryover of alloying metal species was observed. At realistic operation conditions for steam electrolysis, the gas preheater caused a considerable release of silicon into the steam phase. Two stack experiments were performed with common preheater temperatures and showed lar... [more]

Climate change is one of the main problems humanity is currently facing due to the use of fossil fuels. At present, 20% of the total electricity consumed in buildings worldwide is for air conditioning. The development and use of thermally driven cooling systems is very important, since they can be activated by renewable energies, such as geothermal, reducing the consumption of electricity produced by fossil fuels. In this paper, we analyze a geothermal field located in the state of Jalisco, Mexico, with the aim of comparing the performance of different advanced absorption cooling systems driven by a geothermal heat source. The analysis includes the influence of water temperature obtained from an abandoned geothermal well, using a U tube heat exchanger inside the well. The results show that this well can reach temperatures from 59 °C to 190 °C, depending on the depth of the U tube and the insulation thickness. At a TE = 8 °C, the operating range temperatures were 59−80 °C, 77−110 °C, 13... [more]

As the most reliable alternative energy source for traditional fuel engines, natural gas has been widely used in inland river marine engines. The natural gas engine is faced with the problem of increased cyclic variations under the condition of lean combustion. In this paper, a multi-point injection spark ignition natural gas engine is tested under different lean burn degrees to investigate the correlation between different parameters and cyclic variation, including accumulated heat release, combustion phase and burning rate. The purpose is to clarify the optimized technical route for marine natural gas engine. A new method to quantify the correlation between parameters and cyclic variation is proposed. The maximum explosion pressure of combustion and its phase are used as the parameters to characterize the cyclic variation. Different parameters are then nonlinearly fitted to it, and the R-S value of the fitting is used to quantify the correlation between parameters and cyclic variatio... [more]

Bone diseases such as osteoporosis, delayed or impaired bone healing, and osteoarthritis still represent a social, financial, and personal burden for affected patients and society. Fully humanized in vitro 3D models of cancellous bone tissue are needed to develop new treatment strategies and meet patient-specific needs. Here, we demonstrate a successful cell-sheet-based process for optimized mesenchymal stromal cell (MSC) seeding on a β-tricalcium phosphate (TCP) scaffold to generate 3D models of cancellous bone tissue. Therefore, we seeded MSCs onto the β-TCP scaffold, induced osteogenic differentiation, and wrapped a single osteogenically induced MSC sheet around the pre-seeded scaffold. Comparing the wrapped with an unwrapped scaffold, we did not detect any differences in cell viability and structural integrity but a higher cell seeding rate with osteoid-like granular structures, an indicator of enhanced calcification. Finally, gene expression analysis showed a reduction in chondrog... [more]

Methods to predict the equilibrium solubility of nonelectrolyte solids are indispensable for early-stage process development, design, and feasibility studies. Conventional analytic methods typically require reference data to regress parameters, which may not be available or limited for novel systems. Molecular simulation is a promising alternative, but is computationally intensive. Here, we demonstrate the ability to use a small number of molecular simulation free energy calculations to generate reference data to regress model parameters for the analytical MOSCED (modified separation of cohesive energy density) model. The result is an efficient analytical method to predict the equilibrium solubility of nonelectrolyte solids. The method is demonstrated for the wastewater contaminants monuron, diuron, atrazine and atenolol. Predictions for monuron, diuron and atrazine are in reasonable agreement with MOSCED parameters regressed using experimental solubility data. Predictions for atenolol... [more]

The experimental investigation presented in this research was performed in order to examine the possibility of the removal of SO2 from flue gases by cleaning with a solution of lime suspension and formic acid (Ca(OH)2 and HCOOH). Research was conducted in a laboratory plant (rotary kiln) of 44 kW. The mass of the lime suspension (LS) was 400 g. The mass of the LS was homogenized (mixed) in a sample cup with 2 g (0.5%), 4 g (1%) and 8 g (2%) of 60% formic acid. The solution was placed in a gas washing bottle, where a partial flow of flue gas generated by the combustion of diesel fuel was injected. Simultaneously with the diesel fuel combustion, SO2 from a bottle was injected in a rotary kiln. The average mass concentration of SO2 in the flue gas at the entry point of the gas washing bottle was around 2900 ppm. The results indicated that the absorption of SO2 by the cleaning of flue gas with LS was 96.83%. Adding formic acid to the LS in mass ratios of 0.5% (2 g), 1% (4 g) and 2% (8 g) r... [more]

Methanol, as a promising carbon-neutral fuel, has become a research hotspot worldwide. In this study, pure gasoline and gasoline blended with five different volume ratios of methanol (10%, 20%, 30%, 50%, and 75%) were selected as test fuels, which were referred to as M0, M10, M20, M30, M50, and M75. The experiments on carbon and pollutant emissions and performance were carried out on a passenger vehicle with gasoline direct injection (GDI) turbocharged engine using the steady-state, new European driving cycle (NEDC), and acceleration approaches. The results show that under steady-state conditions, as the methanol blending ratio increases, the volume of fuel consumption increases. Compared with pure gasoline, the equivalent fuel consumption and the CO2 emissions are reduced by 0.95 L/100 km (10.6%) and 18.95 g/km (9.6%) in maximum extent by fueling M75, respectively. In the NEDC, the CO2 emissions of M30 are reduced by 5.46 g/km (3.7%) compared with pure gasoline. After blending methano... [more]

As obtained geofluids from enhanced geothermal systems usually have lower temperatures and contain chemicals and impurities, a novel power cycle (NPC) with a unit capacity of several hundred kilowatts has been configured and developed in this study, with particular reference to the geofluid temperature (heat source) ranging from 110 °C to 170 °C. Using a suitable CO2-based mixture working fluid, a transcritical power cycle was developed. The novelty of the developed power cycle lies in the fact that an increasing-pressure endothermic process was realized in a few-hundred-meters-long downhole heat exchanger (DHE) by making use of gravitational potential energy, which increases the working fluid’s pressure and temperature at the turbine inlet and, hence, increases the cycle’s power output. The increasing-pressure endothermic process in the DHE has a better match with the temperature change of the heat source (geofluid), as does the exothermic process in the condenser with the temperature... [more]

Electric vehicles (EVs) and hybrid electric vehicles (HEVs) are a new trend for the vehicle industry, due to the environmental regulations of the internal combustion engine (ICE) and pollutant emission of transportation. However, despite being very promising, the durability of the battery, due to overheating, is still an obstacle. In particular, electric vehicle batteries are manufactured with high voltage and high capacity to ensure power and energy efficiency. For this reason, a high temperature is generated in the system, which reduces the battery performance and life cycle. In this study, three different layouts, based on a direct contact air-cooled system, are designed to compare and improve the cooling performance. Further, a battery cooling test is conducted to verify the designed model. The results show that the spoiler model reduces the maximum battery temperature by (about) 16%, and effectively improves the temperature distribution of the battery cell by (about) 65%, when com... [more]

Plastic products are widely used due to their superior performance, but there are still limitations in the current methods and technologies for recycling and processing of waste plastics, resulting in a huge wasting of resources and environmental pollution. The element composition of waste plastics determines its great gasification potential. In this paper, three different waste plastic gasification processes are designed in a process simulator based on the conventional Integrated Gasification Combined Cycle (IGCC) system to achieve waste conversion and utilization as well as carbon capture. Design 1 is based on the cryogenic air separation (CAS) process to obtain oxygen, which is sent to the gasifier together with steam and pretreated waste plastics. The synthesis gas is purified and synthesized into methanol, and the residual gas is passed to the gas turbine and steam turbine to achieve multiple production of heat, electricity, and methanol. Design 2 uses a Vacuum Pressure Swing Adso... [more]

Prognostics is an AI-based technique for predicting the degrading/damaging behavior and remaining useful life (RUL) of a system, which facilitates a cost-effective and smart maintenance process. Many prognostics methods have been developed for various applications, such as bearings, aircraft engines, batteries, and fuel cell stacks. Once a new prognostics method is developed, it is evaluated using several metrics based on the true value of the RUL. However, these typical evaluation metrics are not applicable in real-world applications, as the true RUL cannot be known before the actual failure of a system. There are no ways to determine the reliability of prognostics results in practice. Therefore, this article presents the credibility criteria of prognostics results based on prediction intervals (PI), which are known values, unlike the true RUL. The PI-based credibility criteria for prognostics results are explained with two simple examples under different levels of noise to help with... [more]