Modern textronic RFID transponders offer a lot of new possibilities for household appliances designers. Possibility to implement new functions is most evident in clothes washing and ironing techniques, where the information stored in the memory of the RFID transponder sewn into the textiles can be used to choose the most appropriate ironing program for a given type of fabric or to select the best washing program for different clothes placed in a drum of washing machine. The purpose of the work was to propose, design, and develop a laboratory stand to demonstrate usage of RFIDtex transponders in a washing machine. The developed device enabled simulation of the presence of textiles equipped with RFIDtex transponders in a washing machine drum. A set of measurements of the constructed device readout efficiency of textronic transponders placed in the drum was also performed. The device firmware, which manages multiple data readings from tags inside the drum for the performed by integrated R... [more]

In this study, the possibility of sector coupling with biological Power-to-Methane to support and stabilize the energy transition of the three major sectors of electricity, heat, and gas was addressed. For this purpose, the energy cell simulation methodology and the Calliope tool were utilized for energy system optimization. This combination provides detailed insights into the existing dependencies of consumers and fossil and renewable energy suppliers on a local scale. In this context, Power-to-Methane represents an efficient technology for quickly and effectively exploiting unused electricity potential for various sectors and consumers. It was found that, even in regions with low wind levels, this surplus electricity potential already exists and depends on various influencing factors in very different ways. The solar influence on these potentials was considered in connection with gas-fired cogeneration plants for district heating. It was found that the current heat demand for distric... [more]

The Special Issue entitled “Novel Numerical Methods in Heat and Mass Transfer” focuses on such issues as CFD modeling of fluid flow, heat transfer characteristics, mass transfer, phase-change and heat exchangers. The Guest Editors of this Special Issue, under the support and auspices of the publishing house, and through its editors, invited the authors to publish their latest achievements in the area of numerical methods used in the area of heat and mass transfer. A short overview of the successful invited submission articles devoted to the above-mentioned subject is presented with the hope that these valuable works will be of interest to a wide range of readers, as the topic is important and worth further scientific attention.

A method is proposed for optimizing circuits of sequential devices which are used in cyber-physical systems (CPSs) implemented using field programmable gate arrays (FPGAs). The optimizing hardware is a very important problem connected with implementing digital parts of CPSs. In this article, we discuss a case when Mealy finite state machines (FSMs) represent behaviour of sequential devices. The proposed method is aimed at optimization of FSM circuits implemented with look-up table (LUT) elements of FPGA chip. The method aims to reduce the LUT count of Mealy FSMs with extended state codes. The method is based on finding a partition of the set of internal states by classes of compatible states. To reduce LUT count, we propose a special kind of state codes named composite state codes. The composite codes include two parts. The first part includes the binary codes of states as elements of some partition class. The second part consists of the code of corresponding partition class. Using com... [more]

According to the objectives of the Paris Agreement on climate change, the European energy supply must be fully decarbonised by 2050. For the power sector, a massive deployment of decentralised renewable technologies will be required to provide carbon-free electricity. However, other energy-intensive sectors such as gas, heat, transport, and the industrial sectors are more challenging to decarbonise, since they rely mostly on liquid and gaseous fuels. Consequently, exploiting the synergies between energy vectors in an integrated, multi-energy system represents an opportunity for a cost-effective transition towards a carbon-free economy. The objective of this study is to provide insights on the coupling of power and residential heat supply systems in a centralised multi-energy system by developing a linear program that optimises the interactions between energy carriers such as electricity, heat, hydrogen, biomass, and methane to minimise the long-term investments in generation and storag... [more]

With economic development, the output of municipal sludge (MS) continues to increase, and the effective utilization of corn straw (CS) also plays an important role in promoting “carbon neutrality”. The mixed combustion of solid wastes is a very environmentally friendly technology; however, little research has occurred regarding the combustion characteristics and reaction kinetics of MS and CS in a fluidized bed. Therefore, this study used a micro-fluidized bed and process mass spectrometer to evaluate the mixed-combustion characteristics of MS and CS and analyze the effects of the temperature and mixing ratios on the reaction rate. Isothermal kinetics were used to calculate the activation energy, pre-exponential factors, and other kinetic parameters of this reaction. The results showed that with an increasing reaction temperature, the combustion reaction rate of MS and CS under different mixing ratios increased. The reaction rate of mixed combustion of MS and CS was greater than that o... [more]

Using straw and herbaceous crops to replace or augment fossil fuels is becoming popular as access to forest biomass becomes environmentally stricter and more expensive. The low bulk density raw biomass is pre-processed and densified into pellets to facilitate handling and use. Dust is generated during collection, baling and debaling, grinding, drying, and densifying processed herbaceous biomass. Abundant literature deals with dust generated during the industrial handling of woody biomass, grains, and other crops like cotton. But the information on handling herbaceous biomass in the open literature is scarce. This paper reviews the available literature on dust generation from handling and processing of herbaceous biomass. Limited available data shows that herbaceous biomass species have a lower ignition temperature than woody biomass. The paper identifies several crucial pieces of information needed to ensure safety in the handling and pelleting of herbaceous crops.

The large fluctuations in charging loads of electric vehicles (EVs) make short-term forecasting challenging. In order to improve the short-term load forecasting performance of EV charging load, a corresponding model-based multi-channel convolutional neural network and temporal convolutional network (MCCNN-TCN) are proposed. The multi-channel convolutional neural network (MCCNN) can extract the fluctuation characteristics of EV charging load at various time scales, while the temporal convolutional network (TCN) can build a time-series dependence between the fluctuation characteristics and the forecasted load. In addition, an additional BP network maps the selected meteorological and date features into a high-dimensional feature vector, which is spliced with the output of the TCN. According to experimental results employing urban charging station load data from a city in northern China, the proposed model is more accurate than artificial neural network (ANN), long short-term memory (LSTM... [more]

Hydropower is a clean and renewable energy, fundamental to the attainment of a sustainable society. Despite its efficacy and success, there is a need to address the hydroelectric stations’ oil throwing and mist leakage, resulting in the deterioration of the generating units, water, and biodiversity. The conventional engineering measures to deal with oil mist leakage include: the reduction in the operating pad and oil temperature, optimization of the oil circulation loop in the oil tank, improvement of the sealing performance, and design of the oil mist emission device. However, the problem of oil mist leakage of bearings is complex, intractable, and cannot be solved by only one method. Numerical simulation can help to solve the oil mist problem and make up for the shortage of engineering measures. Yet, the mass transfer, involving multi-component and multi-phase flow, becomes a limitation for many numerical studies. As a result, this paper seeks to integrate the solutions by reviewing... [more]

As renewable energy penetrates the power system, system operators are required to curtail output power from generation units to balance the power supply and demand. However, large curtailment from wind power plants (WPPs) may instantly cause excessive output power decrement, causing system frequency to drop significantly before reaching its nominal value. In order to solve this problem, this paper proposes a cooperative control framework to determine the operation of WPPs in two control methods, which are the stepwise inertial control (SIC) method and the curtailed control method. The proposed framework first determines the WPPs to operate in the curtailed control method to provide the required power curtailment. Next, it determines the WPPs to operate in the SIC method considering their releasable kinetic energy to provide an effective inertial response and compensate for the sudden excessive output power decrement caused by other WPPs operated in the curtailed control method. Therefo... [more]

This paper presents an assessment of the impact of the COVID-19 pandemic on the waste management sector, and then, based on laboratory tests and computer calculations, indicates how to effectively manage selected waste generated during the pandemic. Elemental compositions—namely, C, H, N, S, Cl, and O—were determined as part of the laboratory tests, and the pyrolysis processes of the above wastes were analysed using the TGA technique. The calculations were performed for a pilot pyrolysis reactor with a continuous flow of 240 kg/h in the temperature range of 400−900 °C. The implemented calculation model was experimentally verified for the conditions of the refuse-derived fuel (RDF) pyrolysis process. As a result of the laboratory tests and computer simulations, comprehensive knowledge was obtained about the pyrolysis of protective masks, with particular emphasis on the gaseous products of this process. The high calorific value of the pyrolysis gas, amounting to approx. 47.7 MJ/m3, encou... [more]

Serving as a key component of the core engine, the high-load axial compressor is expected to have high performance, which determines several critical parameter levels of the aero-engine. The unsteady effect on the performance induced by the interaction among different rotors should not be ignored during the design of a high-load compressor. The interaction between R1 (the first rotor row) and R2 (the second rotor row) rotors of a transonic axial compressor was measured in detail using high-frequency pressure fluctuation sensors, aiming to reveal the evolution and distribution characteristics of the R1 sweep effect inside the R2 passage. The results show that near choke and design points, the interaction between the R1 oblique shock wave at the leading edge and the high-pressure region on the blade pressure side triggers the R1-2BPF (blade passing frequency) disturbance, which is different from the traditional harmonic of the blade wake disturbance. A ‘long tail’ flow structure, which i... [more]

Lithium-ion batteries (LIBs) are employed when high energy and power density are required. However, under electrical, mechanical, or thermal abuse conditions a thermal runaway can occur resulting in an uncontrollable increase in pressure and temperature that can lead to fire and/or explosion, and projection of fragments. In this work, the behavior of LIBs under thermal abuse conditions is analyzed. To this purpose, tests on NCA 18,650 cells are performed in a cone calorimeter by changing the radiative heat flux of the conical heater and the State of Charge (SoC) of the cells from full charge to deep discharge. The dependence of SoC and radiative heat flux on the thermal runaway onset is clearly revealed. In particular, a deep discharge determines an earlier thermal runaway of the cell with respect to those at 50% and 100% of SoC when exposed to high radiative heat flux (50 kW/m2). This is due to a mechanism such as an electrical abuse. Cell components before and after tests are investi... [more]

The interest in passive construction that has low demand for thermal energy continues to grow every year. It is related to both the reduction in maintenance costs of buildings and the growing environmental awareness in societies. Passive houses are characterised by very good thermal insulation properties of their external partitions. This paper presents the results of tests on the thermal conductivity for three different types of building materials, assuming their use as thermal insulation. The materials were subjected to water absorption tests during long-term immersion. The purpose of this study was to simulate water absorption caused by long-term water exposure. The tests were carried out on a perlite concrete block, a sheet of polyurethane foam applied by spraying and expanded clay in a loose form in three different fractions. The tested insulation materials were selected due to their different form, structure, and porosity characteristics, which largely determined the value of the... [more]

In recent years, the dramatic increase of greenhouse gases concentration in atmosphere, especially of carbon dioxide, determined many researchers to investigate new mitigation options. Thermodynamic studies play an important role in the development of new technologies for reducing the carbon levels. In this context, our group investigated the phase behavior (vapor−liquid equilibrium (VLE), vapor−liquid−liquid equilibrium (VLLE), liquid−liquid equilibrium (LLE), upper critical endpoints (UCEPs), critical curves) of binary and ternary systems containing organic substances with different functional groups to determine their ability to dissolve carbon dioxide. This study presents our results for the phase behavior of carbon dioxide + n-butanol structural isomers binary systems at high-pressures. Liquid−vapor critical curves are measured for carbon dioxide + isobutanol and carbon dioxide + tert-butanol binary systems at pressures up to 147.3 bar, as only few scattered critical points are av... [more]

The deep learning (DL) approaches in smart grid (SG) describes the possibility of shifting the energy industry into a modern era of reliable and sustainable energy networks. This paper proposes a time-series clustering framework with multi-step time-series sequence to sequence (Seq2Seq) long short-term memory (LSTM) load forecasting strategy for households. Specifically, we investigate a clustering-based Seq2Seq LSTM electricity load forecasting model to undertake an energy load forecasting problem, where information input to the model contains individual appliances and aggregate energy as historical data of households. The original dataset is preprocessed, and forwarded to a multi-step time-series learning model which reduces the training time and guarantees convergence for energy forecasting. Furthermore, simulation results show the accuracy performance of the proposed model by validation and testing cluster data, which shows a promising potential of the proposed predictive model.

Developing new wave energy technologies is risky, costly and time-consuming. The large diversity of concepts, components and evaluation criteria creates a vast design space of potentially feasible solutions. This paper aims to introduce a novel methodology for the holistic assessment of wave energy capabilities in various market applications based on sound Systems Engineering methods. The methodology provides a consistent hierarchy of performance metrics relevant to the given system of reference, design activity and development stage under consideration as a means to scrutinise wave energy requirements. Full traceability of system requirements and performance metrics is then facilitated by multi-criteria decision tools and aggregation logic, respectively. The qualitative assessment in the case studies has resulted in very different rankings of System Drivers and Stakeholders for the two market applications considered. However, the Stakeholder Requirements and Functional Requirements pr... [more]

In order to predict the circuit response of a Gas Discharge Tube (GDT) to an electromagnetic pulse, a “black box” model for a GDT based on a machine learning method is proposed and validated in this paper.Firstly, the machine learning model of the Elman neural network is established by taking advantage of the existing measurement data to dampen the sinusoid signal, and then the established model is adopted to predict the response waveform of an unknown injection current grade and frequency.Without considering the complex physical parameters and dynamic behavior of GDTs, the Elman neural network modeling method is simpler than the existing physical or Pspice model.Validation experiments show a good agreement between the predicted and the measured waveforms.

This Special Issue focuses on progress in energy transition planning [...]

Concentrating solar power (CSP), also known as solar thermal electricity (STE), is increasing its deployment worldwide. One of the potential ways to decrease costs in CSP plants is the improvement of corrosion resistance between the heat transfer fluid (HTF) and storage materials, and the materials used for pipes, tanks, containers, and receivers. This paper assesses the literature on this topic (290 publications) through a bibliometric analysis, identifying the trends of the research, the topics of most interest to researchers, and literature gaps. Most documents are from Spain, Germany, and the United States of America. Results show that the most recent approaches for corrosion migration are selective coatings and the use of nanoparticles to reduce corrosiveness. The use of nitrates is changing to other salts such as chloride mixtures and potassium compounds. In addition, the techniques used to evaluate corrosion results are dominated by scanning electron microscopy (SEM), X-ray diff... [more]

A numerical study is conducted to evaluate the steady natural convective heat transfer problem and entropy generation of both single wall (SWCNT) and multi wall (MWCNT) nanoparticles with water as a base liquid over two spaced spheres. The isothermally heated spheres are located between two plates of short length. The cooled plates are maintained at different inclination angles. A numerical approach based on the finite volume method and multigrid acceleration was used to solve the governing equations. The effects of nanoparticle type, volume fraction, the inclination angle of the plates and the Rayleigh numbers are well-considered. Results reveal that there is a remarkable enhancement of the average Nusselt number over the plates for MWCNT nanoparticles with 63.15% from the inclination angle 0° to 30°. Furthermore, optimal heat transfer rates over the plates for MWCNT nanoparticles equates to 1.9, which is obtained for the inclination 30° and a Rayleigh number of 106. However, for SWCN... [more]

The energy transition to renewable energy is inevitable since fossil fuels are a finite source [...]

Wave velocity under different pressure and temperature (PT) conditions plays an important role in the exploration of oil and gas reservoirs. We obtained the mineral composition and porosity of 20 underground sandstone and mudstone samples in Yinggehai Basin via X-ray diffraction and porosity measurements. Using high-frequency ultrasound, the P- and S-wave velocities of four samples under high temperature and overpressure conditions were found to vary significantly, owing to the material composition and porosity. According to the comparison between the experimental conclusion and the well-logging data, the genesis of false bright spot and dark spot gas reservoirs in the study area was analyzed. The variation in P-wave velocity under different temperature and pressure conditions was explained with the PT coefficient. The traditional pressure−velocity and temperature−velocity prediction methods were improved and applied to well-logging data. Herein, the velocity of P- or S-waves of sand a... [more]

The paper concerns a significant problem in the diagnostics of industrial processes, which is the need to achieve high fault distinguishability. High distinguishability results in the generation of precise diagnoses that enable making appropriate security decisions. In the known approaches, the efforts to obtain high distinguishability are focused on the selection of an appropriate set of generated residuals. The paper presents a new method of diagnostic reasoning using the notation of faults/diagnostic signals’ relations in the form of a Fault Isolation System (FIS), which enables the use of multivalent diagnostic signals. In addition, the proposed method uses knowledge (usually incomplete) about the sequence of symptoms. Reasoning was carried out on the basis of simple, physically possible signatures, resulting from the FIS. Assumptions and a diagnostic algorithm are given. The reasoning algorithm works in a step-by-step manner, after observing further symptoms. In each reasoning ste... [more]

A hybrid air conditioning system, which is composed of a novel gravity-assisted heat pipe (GAHP)-based indirect evaporative cooler (IEC) and direct expansion (DX) cooling coil, is proposed and investigated here. After developing a mathematical model to describe the performance of the GAHP-based IEC, the hybrid system is evaluated during the cooling design day for providing thermal comfort for an office building in Poland. The results are obtained and compared with the combination of a rotary heat exchanger (RHE) and DX cooling coil as the conventional hybrid system. The comparison is performed by analyzing cooling capacity, electricity consumption, and coefficient of performance profiles, which describe the technical, energy, and efficiency aspects, respectively. The results show that the GAHP-based IEC hybrid system is able to enhance the energy performance significantly compared to the conventional one. The proposed hybrid HVAC system improves COP by 39.2% and reduces electricity con... [more]