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Recently, radioactive wastes are inevitable by-product due to rapid development and use of nuclear energy. Especially, there are large amount of liquid radioactive wastes to control nuclear fission reaction at nuclear generating station. In order to reduce total volume of solution state radioactive wastes, people have used solar evaporation without any specific instrument and it takes long time to get liquid state concentrated radioactive waste which is inefficient process. Herein we propose Janus-type membrane with different surface hydrophilicity toward efficient solar steam generation to concentrate radioactive liquid wastes. We used vapor deposition polymerization method to introduce polypyrrole (Py) and polystyrene (PS) on the top and bottom side of a cellulose paper. Py coating broadens the absorption wavelength range for enhanced photo-thermal energy conversion. Hydrophobic PS coating not only makes membrane easy to floating on water but also prevents salt accumulation during evaporation. Using this membrane, we can efficiently concentrate polluted water including Cs ion without salt accumulation on membrane, and thus no specific decrement in evaporation efficiency by time.

Herein, porous WP 2 nanosheet arrays integrated on graphite paper (P-WP 2 NSs/GP) as 3D flexible cathode for electrocatalytic hydrogen evolution reaction (HER) are prepared by in situ phosphidation via vacuum encapsulation assisted by pulsed laser deposition technique. Compared to the electrode without pre-deposition process, the enhanced catalytic activities are attributed to the increased effective catalyst loading and the reinforced charge transport kinetics. The results make the present P-WP 2 NSs/GP as a promising cathode for energy conversion and paves a new way for designing and fabricating efficient electrodes toward HER.

Nowadays, multi-functional systems driven by solar energy have been explored to alleviate the crisis of energy and freshwater scarcity. However, it remains a great challenge to integrate multi-functions into one hybrid system with a monolithic material, which can harvest, convert and store solar energy synergistically. Here, we firstly propose a multi-functional carbon nanotube paper, which starts from a material level to solve these problems. The carbon nanotube paper is fabricated by vacuum filtration. It exhibits high efficiency of solar-thermal conversion. Secondly, three types of energy conversion/storage systems (e.g., solar-thermal evaporation system, solar-thermoelectric generation system, and supercapacitor) are constructed based on the carbon nanotube paper, which extend the research to a device level. The solar-thermal evaporation system shows an evaporation rate of 1.28 kg m-2h−1 under simulated sunlight irradiation of 1 kW m−2. The solar-thermoelectric generation system demonstrates a stable electric power generation with an output voltage of 100 mV under light irradiation of 1 kW m−2. The supercapacitors perform the energy storage function with an areal specific capacitance of 19.6 mF cm−2. These devices and systems can be used in freshwater generation (0.84 kg m-2h−1, sunlight irradiation of 1 kW m−2), water purification/desalination (inorganic ions rejection larger than 99.9%) and portable solar charging system (maximum output voltage of 5 V). Finally, a hybrid energy system is innovatively proposed from the system level to simultaneously produce freshwater, generate and store electric power. Through the synergetic coupling of solar conversion and storage technologies, the hybrid energy system can supply sustainable freshwater and electricity for remote areas in daily life, highlighting the superiority of multi-energy (thermal energy, electrical energy, and electrochemical energy) complementary.

Graphene nanosheet devices have attracted significant interest in transistor and photodetector applications owing to photothermoelectric effects of graphene. However, their solar energy conversion ability has not been fully explored due to disadvantages of their transparency and zero gap semiconductor in this special field. Here, we propose the potential of graphene-carbon nanotube papers for energy conversion and storage under sunlight and heat. We show that macroscopic 3-dimensional structure of graphene-carbon nanotube papers provides advantages over graphene nanomaterials in converting large area power sources, namely solar and thermal energy into considerable current and voltage. We also report a graphene-carbon nanotube paper stack with p-n interfaces that incorporates a solar/thermal energy cell and a p–n junction capacitor, which can be simultaneously used for energy conversion and storage with a charge-storage capacity of 70.5 μC cm−2 at one sun intensity.

This paper investigates the impact of combining CO2 capture and storage with alternative systems for biomass-based combined heat and power production (CHP) in Kraft pulp and paper mills. We compare heat, power, and CO2 balances of systems with alternative configurations of the CHP and CO2-capture systems. Because the captured CO2 comes from renewable biomass, the studied systems yield negative CO2 emissions. It is shown that pulp mills and integrated pulp and paper mills have the potential to become net exporters of biomass-based electricity while at the same time removing CO2 from the atmosphere on a net basis. The study shows that that the overall best CO2 abatement is achieved when CO2 capture is carried out within a biomass integrated gasifier with combined cycle where the syngas undergoes a CO-shift reaction. This configuration combines efficient energy conversion with a high CO2 capture efficiency. Furthermore, cost curves are constructed, which show how the cost of CO2 capture and storage in pulp and paper mills depends on system configuration and the CO2 transportation distance.

Flexible thermoelectric materials are presented with potential applications in electronic devices and energy conversion due to their convenient preparation, good flexibility, and various forms. However, as ductility is rarely observed in inorganic semiconductors and ceramic insulators, reports on applications of inorganic oxide materials in flexible thermoelectric materials are sparse. Here, we report a new method for the synthesis of a flexible Na1.4Co2O4 thermoelectric material based on Na1.4Co2O4 bulk materials, which are prepared by a self-flux method and painted on print paper. Seebeck coefficient and power factor of the obtained thermoelectric material are 78–102 μVK-1 and 159–223 μWm-1K-2, respectively, in a temperature range of 303–522 K, which are superior to those values of other conductive polymers and their compounds. More interestingly, the n-type Na1.4Co2O4 flexible material is obtained in the painting process at higher pressure with Seebeck coefficients of –109 to –183 μVK-1 in a temperature range of 303–522 K. The convenient preparation method of these novel flexible thermoelectric materials may be expanded to the synthesis of other flexible thermoelectric materials, which will be the focus of future work.

A method for the analysis of process energy requirements has been used to identify in an early design stage the potential process retrofit measures in an integrated pulp and paper mill. The minimum energy requirements (MER) of the process were computed by means of a dual representation that segregates the thermodynamic requirement of the process from its technological implementation. Energy and exergy recovery opportunities have been examined to improve the integration of the utility system to the process. An MILP optimisation targeting method has been applied to identify the best energy conversion options and to optimise the production of combined heat and power (CHP). Replacing the steam injections to mixing tanks by heat exchangers would decrease the MER by 10%, and increase the combined production of heat and power by a factor 1.7. Improving the exergy efficiency of the paper drying technology would be more difficult to implement, but the results indicate that this could bring an additional 12% gain of electricity cogenerated with no change to the MER.

Along with the chic fad energy industry field, the graphene application in energy conversion and management does bring about some benefits in terms of the energy transfer and storage development, the achievement it exerts on the multifaceted innovate approaches. Both current and previous studies on energy conversion, energy storage and energy transfer development, many research results are sufficient to show that all graphene products including graphene paper, film, foam and fiber have a significant role in improving performance. In the energy conversion research on the graphene paper, it has been recently demonstrated that putting the graphene into triboelectric nanogenerators practice possesses higher output performance than traditional generator, which has a maximum strain as large as 200% without evident degradation of the electrical properties. In terms of energy transfer, the graphene fiber application on the battery can significantly increase the charge and discharge rates with enhanced storage capacity of 763 F g−1. On the energy storage research, the graphene foam can enhance a high density of solar thermal storage up to 269.8 kJ kg−1 for long-term. Nano-graphene and graphene coating provide feasibility for the miniaturization of energy storage equipment which inspired the possibility for portable and foldable devices. The work done in this paper can effectively help promote the application of graphene in energy field. Based on our work, the researchers can choose graphene products (graphene paper, graphene film, graphene foam or graphene fiber) efficiently according to the research object in the future.

Energy cost contributes to the second largest portion of the starch-processing plants’ expenditure. Therefore, to improve energy efficiencies, CHP systems installed in cassava starch plants are considered. Hence, their energy conversions and efficiencies are investigated. Where, the structure of the plant is modeled, the factors of biogas, power, heat and the biogas distribution ratio are focused; the relationships among those factors are resolved by establishing formulas based on theoretical analysis. Results show: the minimum demand of biogas for 1 t starch product is 134.8 m3, which can produce 704.7–875.6 MJ of electric energy and total 1311.0 MJ of heat for starch production by a CHP-boiler system. The steam produced there can fully satisfy the heat demand under the three strategies, while a minority of excess electricity is available under the strategy 3. The total energy efficiencies of the CHP-boiler system are 70.6%, 70.1% and 67.1% corresponding to the three strategies; those are 8.4%–11.9% more than the efficiency of 58.7% by the original system. The total reduction of CO2 emissions is 2017.1–2508.3t/a for a 200 t/d cassava starch plant using CHP-boiler system; which investment costs 27.24 million CNY in total, and will be pay back in 3.18 years.

A multi-functional electrochromic material which modulates light over a wide spectral range and stores electrical energy is an intriguing substance, which would lead to a variety of novel applications, such as smart windows for energy-efficient buildings, solar power storage, nonemissive displays, electronic paper, optoelectronic switches, and variable-reflectance mirrors/surfaces. Developing such a versatile material entails merging the electrochromic phenomenon with electrical-chemical energy conversions in an electrochromic-battery platform. However, the challenges related to transition metal oxide electrochromic-batteries include poor energy storage, low optical contrast, and high fabrication cost. Here, we demonstrate the synthesis of aqueous nanocrystalline colloidal molybdenum oxide in a matrix of tungsten molybdenum oxide (MoO3-W0.71Mo0.29O3) for solution-processed fully reversible switching electrochromic-battery electrodes. The hybrid material exhibits both 50% optical contrast modulation over a wide optical bandwidth and an improved Columbic efficiency. An 8 × 8 cm2 energy storing smart (ESS) window is assembled to demonstrate a functional prototype that can power an LED for more than 10 min when charged under −2.5 V for 1 min. The enhanced electrochromic performance, high energy storage capacity, simple solution processability, versatility for large area fabrication, and low cost make this nanocrystalline MoO3-W.71Mo.29O3 composite a promising material with the potential to be deployed ubiquitously in energy-efficient smart window architectures.

The sunlight-heating and electricity-heating interfacial evaporation membrane (SHEHIEM), which is prepared mainly using wood pulp and MWCNTs and is directly driven by sunlight and electricity from photovoltaic panels, is adopt to produce more steam at a very low cost. The results show that some SHEHIEMs of different compositions, having higher steam yield in sunlight heating, can hardly run in electricity heating and the season is that the resistance of SHEHIEM changes sharply during absorbing water. Thus, according to resistance, hydrophilicity, steam yield, SEM, XRD, FTIR, TG, absorption spectra and tensile strength, the composition of SHEHIEM is determined and optimized. When the SHEHIEM is operated in only electricity heating, only sunlight heating, sunlight and electricity heating (S&E heating), the steam yield of S&E heating is the highest and 1.30 kg/m2 for 0.5 KW, 1.90 kg/m2 for 1 KW, 2.37 kg/m2 for 1.5 KW, 2.86 kg/m2 for 2 KW and 3.23 kg/m2 for 2.5 KW, respectively. Meantime, its energy conversion efficiencies are also the highest and 62.7% for 0.5 KW, 68.4% for 1 KW, 68.8% for 1.5 KW, 69.3% for 2 KW and 67.2% for 2.5 KW, respectively, and the SHEHIEM shows synergistic effects. For S&E heating of 1 kW/m2 and 2 kW/m2, 10 h consecutive tests show that the SHEHIEM has better stability. After evaporation, all the detected indicators meet the drinking water standard of WHO. In the open, when the SHEHIEM is run for 7 h in winter, the production water mass and energy conversion efficiencies are 9.03 kg/m2 and 55.4% for 1 KW and 15.67 kg/m2 and 61.0%.

Currently, energy conversion methods in nanochannels have been developed for both fundamental sciences and technological applications. Graphene oxide membranes with excellent properties possess potential applications in numerous fields. Due to the confinement of nanocapillaries within graphene oxide membranes and the mobility difference of ions, an electricity generation process has been achieved using graphene oxide membranes. In this study, for the first time, the influence of source concentration, applied pressure and membrane thickness was investigated on electricity generation in aqueous environment. The results revealed that these three factors could successfully control the electricity generation with graphene oxide membranes. Electrical potential difference would become larger with increasing the source concentration and membrane thickness. In contrast, the applied pressure was not well-suited to capture energy from sources. This provided new insights into the design and utilization of graphene oxide films for highly efficient energy harvesting.

The chemical looping gasification (CLG) between biomass and Fe2O3 be expressed as a potential hydrogen production technology as long as Fe2O3 could be effectively alkali-modified and enough steam could be supplied to the biomass gasification process. Therefore, a one-step strategy was developed herein by introduces KNO3-containing acetic acid liquid waste to modify Fe2O3 and provide enough steam to improve the efficiency of hydrogen production from corn stalk. Experiments under different excess oxygen ratio (Ω), temperature (T) and potassium concentrations (mKNO3) shows that these parameters have obvious effects on biomass CLG, and the highest hydrogen yield of 1.79 L is obtained at Ω = 0.2, T = 750 °C and mKNO3 = 8%. The kinetic and thermodynamic analysis further verifies that KNO3-containing acetic acid liquid waste boosts biomass CLG for hydrogen generation. The proposed CLG strategy has dual advantages of waste treatment and energy conversion.

The low-cost biocathode microbial electrochemical system (MES) with microbial separator (MS) is promising for the practical application in wastewater treatment. To evaluate the potential realizable advantages for future full-size MESs, four 2-Liters MES modules with MS are constructed and their energy conversion, biomass metabolism and pollution degradation are systematically investigated. The mass and energy flow for MES with raw domestic wastewater is built under maximum power point (Pmax), maximum current point (Imax), and open circuit (OC) modes. The chemical oxygen demand (COD) removal rates are 0.831 and 0.846 kg m−3 day−1 in Pmax and Imax modes, while that of OC is 0.609 kg m−3 day−1. The effluent COD concentrations at Pmax and Imax are stable at 41 ± 2 and 37 ± 2 mg L−1, while that of OC is up to 101 ± 4 mg L−1. The observed sludge yield is only 23.4% (Pmax) or 19.5% (Imax) of the OC mode with much higher sludge calorific values. For the raw wastewater treatment, the direct electricity harvest and reuse from MES units are unrealistic and uneconomical due to its low energy efficiency. But the high COD removal efficiency and low observed sludge yield are the realizable advantages for practical applicated MESs.

Manipulating basal plane structure of graphene for advanced energy conversion materials design has been research frontier in recent years. By extending size of defects in the basal plane of graphene from atomic scale to nanoscale, graphene with in-plane holes can be synthesized by multiple steps oxidation and reduction of defective graphene oxide at low concentration. These complicated and low yield synthetic methods largely limited research and applications of holey graphene based high performance energy conversion materials. Inspired by graphene in-plane holes formation mechanism, an easy and scalable synthetic approach has been proposed in this work. By oxidizing widely available defective graphite mineral under high concentration, holey graphene oxide has been scalable synthesized. Through simple reduction of holey graphene oxide, nitrogen doped holey graphene with high volumetric capacitance of 439 F/cm 3 was obtained. We believe this breakthrough can provide a feasible synthetic approach for further exploring the properties and performance of holey graphene based materials in variety of fields.

With huge demand of herbal medicine worldwide, herb residue (HR) treatment is attracting growing attention. This work proposed an integrated energy conversion system to treat and utilize HR, which contained a crushing and drying section to pretreat HR, a gasification section to convert HR into syngas, and a boiling section to produce hot steam for HR drying and herb steaming. A pilot scale plant was established to validate its feasibility. The results showed that HR with particle size below 10 mm and moisture content about 20 wt% was qualified as gasification feedstock. The energy efficiency, syngas heat value, and syngas yield during gasification reached 76.1%, 5.7 MJ/Nm3, and 0.6 Nm3/kgHR, respectively. When treating each kg of HR, 1.0167 kg of wastewater was emitted, which primarily came from HR dehydration and herb steaming. Meanwhile, 0.3292 kg of hot steam with 0.89 MJ of enthalpy would be produced per kg of HR as net energy output. This integrated system fully considered the upstream and downstream adaption of HR gasification technique. Highly efficient disposal and utilization of HR were thus achieved. It is hoped that this work could promisingly enhance the overall efficiency of herbal medicine production industry.

Empty fruit bunches (EFB) of oil-palm are one of the most recent renewable energy resources. The objective of this study is to find the most economically-feasible pathway among three energy conversions from 400 t/d wet EFB, which are bioethanol and jet fuel by bioconversion, combined heat and power via gasification, and hydrocarbons through fast pyrolysis and biooil upgrading. A hierarchical four-level economic potential approach (4-level EP) was employed to perform the preliminary techno-economic analysis (TEA) for the three pathways. The 4-level EP includes the input/output structure, the flowsheet structure, the heat integration (HI), and the economic feasibility. The economic potential of the three plants was compared at each level, and the most promising process among them was identified at Level 4, where economic criteria including return on investment (ROI), payback period (PBP), and internal rate of return (IRR) were evaluated. It was found that the biooil hydrocarbon plant is most economical due to the highest economic potential, ROI, and IRR. The heat consumption was reduced considerably by HI in the bioethanol and jet fuel plant. The sensitivity analysis informed that the plant size, the product yield, and the total capital investment highly influenced ROI and PBP in all three processes.

Energy conversion efficiencies of three pyrolysis reactors (bench-scale auger, batch, and fluidized bed) were investigated using rice straw as the feedstock at a temperature of 500 °C. The highest bio-oil yield of 43% was obtained from the fluidized bed reactor, while the maximum bio-char yield of 48% was obtained from the batch reactor. Similar bio-oil yields were obtained from the auger and batch type reactors. The GCMS and FTIR were used to evaluate the liquid products from all reactors. The best quality bio-oil and bio-char from the batch reactor was determined to have a heating value of 31 MJ/kg and 19 MJ/kg, respectively. The highest alkali mineral was found in the bio-char produced from the auger reactor. The energy conversion efficiencies of the three reactors indicated that the majority of the energy (50–64%) was in the bio-char products from the auger and batch reactors, while the bio-oil from the fluidized bed reactor contained the highest energy (47%). A Sankey diagram has been produced to show the flows of product energy from each pyrolysis process. The result will help determine which conversion process would be optimal for producing specific products of bio-char, bio-oil, and gas depending on the needs.

A new tool was developed for second generation ethanol production from non-sterilized beet molasses to energy recovery from the agro-industrial byproduct. The rotary biofilm reactor (RBR) used in repeated-batch fermentation for long-term bioethanol production showed high energy recovery efficiency. This study will serve as a base line of initial studies in this field as no reports are available regarding the application of RBR for bioethanol production. Repeated-batch fermentations were carried out by replacement of the fermentation broth (3.5 L) by equal volume of fresh medium or with 15% and 30% recycling volume in RBR and the reactor without the discs. The fermentation was carried out under the following conditions: an inoculum concentration of 5.6 g dry baker’s yeast/L, initial sugar concentration of 15% (w/v), initial pH 5.0, temperature 30 °C, and rotation speed of 40 rpm. The high bioethanol concentration (average value 52.3 g/L) and the average bioethanol productivity (1.45 g/L/h) were stable for 60 days by recycling 30% of the volume of the broth every 36 h in repeated-batch fermentation using the RBR. The energy evaluation data indicated a positive energy balance with an energy ratio of 1.63 MJ/MJ. The other energy indicators such as energy consumption, energy conversion, energy yield, and energy recovery were 16.5 MJ/kg bioethanol produced, 4.7 MJ/kg beet molasses, 1.3 MJ/100 g sugar utilized, and 84.8%, respectively. The results showed that non-sterilized beet molasses is a promising feedstock for bioethanol production in industrial scale by Saccharomyces cerevisiae using the RBR and this process is considered energetically feasible.

Technical viability of two small-scale electricity generation pathways based on willow short rotation coppice biomass was evaluated using a Screening Life Cycle Assessment (LCA) procedure. The system inputs included fuel and oil consumption in machine operations, fertilizer and herbicide production, transportation of willow chips biomass, and biomass-to-energy conversion. The analysis was based on net energy production, energy output–input ratio, and the related CO2 emission. Sensitivity analysis was conducted to determine the effect of fertilizer type and application technique, harvesting and drying techniques, energy conversion process and chips transportation distance. The results showed that key energy efficiency and environmental compatibility factors include: the choice of drying technique; fertilizer type and application technique (68.2% variation in net energy, 57.7% difference in output–input ratio, respectively), and; the type of biomass-to-energy conversion plant, which had up to 36.4% variation in net energy production, and 96.4% reduction in CO2 emission. Willow chips transportation up to distances of 38 km did not have significant impact on the net energy production and CO2 emission. Chip transportation over distances in excess of 38 km generated significant drop in energy efficiency (25.9% reduction in energy output–input ratio) which underlines the importance of transportation in the overall system productivity.

Energy use patterns and utilisation efficiencies in 40 factories producing palm kernel oil (PKO) in southwestern part of Nigeria were studied. The factories were stratified into small, medium and large scale categories based on the mode of operations and production capacities. Questionnaires were administered on the factories to obtain historical data on petrol, diesel and electricity consumption and PKO production outputs for seven years (1998–2004). Energy use efficiency indicators employed include: energy intensity (EI), energy cost per unit product (EC/P), energy ratio (ER), food energy ratio (FER) and percentage oil yield by weight. Results of the study indicated that averagely, 0.58, 0.53 and 0.74 GJ/103 l of PKO were needed in the small, medium and large PKO factories, respectively. The average food energy ratios in the small, medium and large mills are 2.48, 2.53 and 2.14, respectively. The corresponding values of PKO conversion ratio are 0.43, 0.50 and 0.35. Electrical energy consumption in medium and large mills was lower than thermal energy due to irregularity and decline in electricity supply from the national grid. The results of the study has provided required baseline information needed for budgeting, comparison of yearly energy consumption, forecasting energy requirements and planning expansion in PKO factories.

Conversion of energy with the highest possible efficiency is of primary importance in processes with high intensity of energy flows, among which the most significant are those in thermal power plants. The paper deals with the influence of coal composition on the conversions taking place in power plants. The analysis of energy conversions treats, above all, the heat loss due to the exhaust flue gas. The analyses of the power plants use of electric powers are focused on the processes of coal pulverising and exhaust flue gas cleaning. The results of the analyses are graphically presented.

An overview of the research on biomass upgrading by torrefaction for the production of biofuels is presented. Torrefaction is a thermal conversion method of biomass in the low temperature range of 200–300 °C. Biomass is pre-treated to produce a high quality solid biofuel that can be used for combustion and gasification. In this review the characteristics of torrefaction are described and a short history of torrefaction is given. Torrefaction is based on the removal of oxygen from biomass which aims to produce a fuel with increased energy density by decomposing the reactive hemicellulose fraction. Different reaction conditions (temperature, inert gas, reaction time) and biomass resources lead to various solid, liquid and gaseous products. A short overview of the different mass and energy balances is presented. Finally, the technology options and the most promising torrefaction applications and their economic potential are described.

The accomplishments of the Wood Feedstock Quality activity of Task V of the International Energy Agency's Bioenergy Agreement are described. Areas investigated included energy products and co-products from woody biomass; effects of harvesting, processing and storage on feedstock quality; the effect of feedstock quality on the efficiency of biomass conversion; the potential for biological improvement; the need for standardization of feedstock qualities; and the need for clonal characterization.

International audience; As the energy transformation in the transportation sector is taking place driven by the development of fuel cell technologies, fuel cell hybrid electric vehicles become promising solutions owing to their long driving duration and zero emissions. However, the unsatisfied lifespan of fuel cells is an inevitable obstacle for their massive commercialization. This paper aims to propose an online adaptive prognostics-based health management strategy for fuel cell hybrid electric vehicles, which can improve the durability of the fuel cell thanks to online health monitoring. Here, particle filtering method is adapted for online fuel cell prognostics and the uncertainty of the predicted results is calculated based on the distribution of particles. A health management strategy is developed based on prognostics and a decision-making process is designed by considering the prognostics uncertainty through a decision fusion method. The obtained results show that the developed strategy has effectively improved the durability of the on-board fuel cell by up to 95.4%. Moreover, a sensitivity analysis of the prognostics occurrence frequency and probability calculation has also been conducted in this paper.

The operation stability demands for low and uniform wall temperature in the parabolic trough collector which acts as an energy conversion component in concentrating thermal conversion technology. In order to reduce the local high temperature with moderate pump power consumption, this paper proposed longitudinal swirls impinging cooling method. Three types of novel inclined curved-twisted baffles (A1, A2, and A3) were devised to realize this method. With selecting the absorber tube as research model, this paper numerically compared the impinging cooling characteristics, wall temperature uniformity performance, and efficiency performance by inserting the three types of baffles. The A1 and A2 types each generated a pair of longitudinal swirls while the A3 type generated two pairs of longitudinal swirls. The impinging cooling always appeared near the front edge of inclined baffles. The A1 type was the best in wall temperature uniformity and efficiencies among three baffles. Furthermore, as the inlet temperature increased from 400 K to 600 K at a mass flow rate of 1.13 kg/s in the A1 type tube, the average wall temperature difference between bottom half tube and top half tube was decreased by 55.1%. Meanwhile, the average overall efficiency and exergy efficiency were increased by 0.52% and 0.22%, respectively.

The dynamic effect of coal and gas outburst seriously threatens the safety of underground equipment and workers in mines. In this paper, the models for outbursts are established, and according to the energy transformation during gas expansion process, three parameters of the release of gas pressure potential energy are defined and the gas dynamic characteristics of two-phase flow in the initiation stage are quantitatively studied under the four factors: initial gas pressure, particle volume fraction, particle size and outburst hole size. The gas dynamic characteristics in numerical simulations are verified by experiments. The results show that for the influence of the factors on the gas dynamic characteristics of two-phase flow, initial gas pressure >outburst hole size >particle volume fraction ≈particle size. The solid particles block the pressure potential energy release from chamber, so does the caliber. However, the maximum of pressure drop occurs when the caliber is 80% of the chamber, which explains the outbursts in mines are so violent due to the caliber smaller than the internal space. This paper provides a novel quantitative research method of gas dynamic characteristics of coal and gas outburst, which is of guiding significance to the design of outburst prevention facilities and emergency rescue measure.

Typically, in a solar-to-electricity energy conversion process from a PV solar panel, this mechanism often accompanied with a creation of by-products which refers to unproductive heat on the surface of PV solar panel. This unwanted heat energy produced will lead to reduction of total effective output of electrical parameters due to the negative inversely proportional relationship between PV temperature and output efficiency. Therefore, it is important to cool the temperature of PV panel relatively in optimizing the output efficiency. This paper is focusing on using state-of-arts nano-sized materials (graphene particles (GNP) in a liquid solution) to achieve the cooling desired. In the previous simulation research carried out on the similar subject, it was found that by having multiple channels with equal volume, the cooling effects will be peaked using graphene nanofluids. This paper presents the experimental setup and fabrication methods using GNP nanofluids as key media in studying the effectiveness of GNP in cooling of a flat solar panel through continuous flowing of GNP nanofluids inside multiple micro-sized channels which were made in direct contact with the exposed backside of the PV solar panel. It is expected that GNP with its enhanced thermo-physical properties compared to water, the cooling efficiency will increase subsequently. Cooling effects due to different pumping flowrates were also being studied respectively. Keywords: Nanofluids, Solar panel cooling, Graphene Nanoparticles (GNP), Micro-sized channels

In present situation, the renewable energy sources (RES) are turned into significant part of power system. Such power system is generally acknowledged as the hybrid power system (HPS), which is accountable for meeting its connected load. Battery energy storage (BES) is essentially needed along with RES to deal their intermittency and to commit them as dispatchable sources at some extent. An effective optimal scheduling operation of BES in such systems is a tedious assignment, due to unpredictable nature of RES, load, and electricity tariff. In this paper, a HPS integrated with utility grid (UG) containing wind farm (WF), solar photovoltaic (SPV), BES, and connected load is taken for problem simulation. The main aim of this paper is a day-ahead optimal scheduling of BES with its operational limitations in a HPS. To improve the BES performance, BES scheduling operation is mainly constrained by quick switching cost, energy conversions loss cost along with its state of health condition and charging/ discharging rate (fast or slow) restrictions. Optimization is executed through artificial bee colony algorithm (ABC) and the results are compared or validated using the classical technique, i.e., interior point method (IPM) of MATLAB® fmincon function.

Enhancing the power performance of wave energy converters is undoubtedly a step required to reduce the cost of energy from this source of renewable energy, thereby making it competitive to other sources of renewable energy. Increasing the power absorption can be achieved by utilizing smart and advanced control algorithms. There are theories for a variety of advanced control algorithms, but few have proved stable and reliable for real applications. An often used, and robust method for practical applications, is to apply a simple gain scheduling controller where the control gains are parameterized in function of the sea state, and not at wave-by-wave level. This paper presents a wave-by-wave adaptive controller, which has proven a robust method that can increase the power absorption performance. The use of the wave by wave adaptive controller is achieved by the identification of the instantaneous fundamental frequency in real time. One numerical procedure to achieve this frequency is using non-linear Kalman filters. But the pitfall of these non-linear filters is their sensitivity to the parameter tuning, which decreases practical usability, reliability and robustness. This paper focuses on two complementary topics. The first topic will tackle the implementation of a reliable filter for the identification of the instantaneous fundamental frequency using a particle filter. The second topic will demonstrate the implementation of the wave-by-wave gain scheduling controller. The case study is a scaled absorber of the Floating Power Plant wave and wind energy converter.

Green buildings and neighborhoods can help mitigate impacts of buildings on the environment, society and economy. Many rating systems or tools have been developed worldwide to assess and certificate green buildings or green neighborhoods. Renewable energy plays an important role in achieving green buildings/neighborhoods or zero energy buildings/neighborhoods by reducing fuel consumption and pollution emissions. However, substantial differences exist in assessing or quantifying the renewable energy in green building/neighborhood rating systems. This paper therefore provides a comprehensive review on renewable energy assessment methods adopted in green building/neighborhood rating systems, which would be very helpful to understand and then improve the rating systems. These methods are analyzed and discussed regarding to the calculation way, involved renewable energy types, building characteristics and energy conversion. Then a case study is conducted to quantitatively illustrate the difference of typical renewable energy assessment. Suggestions are summarized to improve the assessment methods. This paper will help investors, users and policy makers understand the rating systems more thoroughly and promote the development of green buildings and green neighborhoods.

CO2 adsorption capture, which could be driven by various forms of energy, has been widely studied in recent years due to the equipment is easy to control with low energy consumption required. However, the existing research on the energy-efficiency aspects of temperature/vacuum swing adsorption (TVSA) for CO2 capture are primarily focus on the quantification of input energy in specific cases. As a classical concept in thermodynamics, entropy has been widely applied in researches on the energy conversion process, which could benefit an in-depth understanding on the mechanism of “heat-generalized chemical energy” conversion. However, an integrated thermodynamic research framework, which could clarify how to conduct a reasonable energy-consumption analysis of TVSA, has not been established yet. In this paper, a simplified thermodynamic cycle of 4-step TVSA was established, with the assumption of CO2 in adsorbed phase as loop fluid. With the application of the thermodynamic research framework proposed in this paper, the entropy analysis on the thermodynamic cycle was conducted. This study is concerned with application of thermodynamics concept to the CO2 adsorption engineering, which is mainly based on classical thermodynamics but also relying on adsorption physics to supply insight into the energy conversion and energy-efficient mechanism of TVSA technologies.

We analyze the computational complexity of the synthesis problem of decentralized energy systems. This synthesis problem consists of combining various types of energy conversion units and determining their sizing as well as operations in order to meet time-varying energy demands while maximizing an objective function, e.g., the net present value. In this paper, we prove that the synthesis problem of decentralized energy systems is strongly NP-hard. Furthermore, we prove a strong inapproximability result. This paper provides the first complexity findings in the long scientific history of the synthesis problem of decentralized energy systems.

In recent year, there has been a dramatic increase in renewable energy from the windiest and solar-rich areas. Consequently, energy storage has many potential applications in generation grid integration, power transmission and distribution of green energy. Polypropylene (PP) is a representative electrical insulator used in electrets and dielectric capacitors in energy storage devices. The properties of PP are severely affected by accumulation of surface charge, and the use of PP remains limited by its low dielectric constant. Adding nanoparticles to PP is an effective way to increase its dielectric constant and enhance the evacuation of electrons both on the surface and in the bulk. Thus, in this paper, we investigated how adding zinc oxide (ZnO) nanoparticles to PP affected its decay characteristics, dielectric constant, and conductivity. In this paper, the mechanisms of surface potential decay were discussed. Adding the ZnO particles increased the dielectric constant and conductivity of the PP. Experiments show that the surface potential of PP with added ZnO particles decayed faster than that of the pure PP. Also, the PP/ZnO nanocomposites showed more partial discharge and more electron transport and evacuation. These results will spur further research into energy conversion and storage using nanotructured materials.

The objective of this paper is to carry out a dynamic exergetic assessment of a large complex building. Results in this paper show that although the building and its Heating, Ventilation, and Air Conditioning (HVAC) systems with an energetic efficiency of 122.6% meet energy performance regulations, their overall exergetic efficiency is extremely low (3.68%). This emphasizes the importance of exergy analysis in buildings to improve the quality match between energy supply and demand, and consequently, to increase the sustainability of the building energy system. From the exergy point of view, the main sources of thermodynamic inefficiencies in the considered building are energy conversion systems, energy distribution layer, and energy released to the environment with 54, 21 and 16% of the total exergy destruction, respectively. However, among these sources of inefficiency, only the last one can be detected through an energy analysis. The exergetic efficiency of the system decreases when the exergy demand decreases, but the same energy sources are used to fulfill the demand. This reveals a potential to improve the efficiency of the building’s energy system through the implementation of an exergy-based control strategy. The high-temperature heating network provides around 26% of the low-temperature heating demand. From the exergy point of view, however, this share is approximately 46%. This indicates that the quality of the supplied energy from the high-temperature heating network is much higher than required and the heat transfer from the high-temperature to the low-temperature heating network decreases the exergetic efficiency of the building.

Spray mixing and combustion processes are regarded as the major factors that determine the energy conversion efficiency and emission level of internal combustion engines. However, the related researches mainly rely on 3D flow simulation or optical engine experiments, which are highly expensive and time-consuming. In order to provide a more convenient solution, this paper developed a one-dimensional semi-phenomenological model to achieve accurate and efficient predictions on spray combustion characteristics. The model was constructed by a dimensionless spray theoretical model and limited experimental data of macroscopic spray characteristics. Inside the proposed model, a physical module was used to physical module spray air-fuel mixing conditions like fuel distribution and evaporation. Besides, an improved Arrhenius-typed correlation concerning injection parameters and environment variables was introduced to describe the chemical ignition characteristic of spray combustion. The optical experiment results showed that this method is simple and effective, and the forecasting is satisfactory. Based on the new model, the influences of blending n-pentanol on the spray combustion characteristics of diesel and biodiesel were investigated. On the physical aspect, the critical fuel concentration at liquid length position decreases with n-pentanol is blended into both fuels in the most cases, but witnessed a significant leap in 1200 K condition, especially for diesel blends; the physical ignition delay times of both diesel and biodiesel blends decreases first and go up later. On the chemical aspect, the join of n-pentanol caused the gap between the physical delay time and the chemical delay time much narrower, but the ignition patterns were different in diesel blends and biodiesel blends. Moreover, this paper proposed a series of correlations focused on the liquid length and ignition delay of n-pentanol blends sprays. These correlations covered wide conditions and showed better prediction accuracy than traditional ones.

Plate heat exchangers have been widely applied in numerous industrial applications since their first commercial exploitation in the 1920s. Enhancing the thermal-hydraulic performance of plate heat exchangers is of crucial importance for the energy conversion as well as for the improvement of the system economy, through savings in the capital investment. The efficiency of a plate heat exchanger can be improved either by optimizing its geometry or using heat transfer enhancement techniques. This paper provides a comprehensive review of previous works regarding the effects of chevron corrugation geometrical parameters on the performance of plate heat exchangers, and the application of heat transfer enhancement techniques in plate heat exchangers, focusing on passive surface techniques and the use of nanofluids. The objective of the paper is not only to describe relevant studies, but also to provide an understanding of the heat transfer mechanisms governing the results, and to evaluate and compare the different heat transfer enhancement techniques. In addition, prospective directions for future research are provided. The review indicates that for the chevron-type plate heat exchanger, the chevron angle is the most influential geometrical parameter by changing the flow structures in the single-phase heat transfer; meanwhile the chevron angle has a significant influence on the heat transfer regions characterized by convection in the two-phase heat transfer. An analysis based on the performance evaluation criteria suggests that the thermal-hydraulic performances of the studies with different geometrical parameters and enhancement techniques are generally higher at low Reynold numbers. Furthermore, the review and analysis indicate that the capsule-type embossing surface and the microstructured surface with a nano- and microporous layer are the enhancement techniques that present the highest performance in single-phase and two-phase heat transfer, respectively.

The manufacturing sector has been one of the most significant energy consuming and CO2 emitting sectors over the past three decades. Therefore, it is important to have energy flow models of manufacturing processes to identify efficiency improvement and waste heat recovery opportunities with very specific targets. One of the best methods to pinpoint such locations is by referring to manufacturing process step models. Such models can be created on a large scale per industry and on small scale per process within an industry branch. Industry level modeling provides energy saving contingency by large magnitude where the impact on the economy and environment can be observed more visibly especially when sequential trends are identified. The methodology, reviewed in this paper, describes how to model energy flows on an industry scale by deriving the connection between key energy conversion activities on the one hand – including energy purchased/sold and onsite electricity generated, and the key end uses on the other hand. Industry-level energy flow model, referred to in this work, does not assume any specific system. That feature makes it scalable and allows analysis of manufacturing at various levels starting with single processes and finishing at sector and national economy levels. A combined analysis of the procedure is described in detail for creating process step models of manufacturing processes. The availability of U.S. national databases to calibrate these models is discussed and the challenges that arise in finding and using such databases are identified and analysed. In addition to addressing generic data issues associated with energy flow models, the paper also focuses on energy and material models and presents several examples of energy-intensive manufacturing processes, producing industrial gases, textiles, pulp and paper. Finally, importance of water use in onsite energy conversion and process end uses in various industries is addressed along with the sources of where this important data can be found to complete the energy flow modeling.

Thermal management of Li-ion cells is critical for safety and performance of energy conversion and storage in battery packs in a variety of applications. Phase change cooling is a promising approach towards this goal. In contrast with several recent papers on experimental measurements of this approach, there is a distinct lack of literature in theoretical modeling of phase change cooling of Li-ion cells. This paper presents a theoretical model for solving the coupled heat transfer problem involving the cooling of a heat-generating Li-ion cell with a phase change material. Results show that while phase change cooling effectively reduces cell surface temperature, the cell core continues to remain quite hot. Improvement in cell thermal conductivity is shown to be critical for fully benefiting from phase change cooling. On the other hand, the impact of increasing thermal conductivity of the phase change material plateaus out at large values. Trade-offs between thermal management and energy storage density of a Li-ion battery pack are analyzed by quantifying the extent of temperature rise and reduction in energy storage density at large discharge rates. Comparison of phase change cooling with convective cooling is also presented, indicating key trade-offs in these approaches. These results contribute towards understanding the fundamentals of phase change cooling of Li-ion cells, as well as improving the performance of practical thermal management systems for Li-ion cells.

With the rapid development of electronic technology, the use of portable and wearable electronics hasbeen widely. In order to eliminate the dependency of low-power electronic devices on batteries and the associated requirement of periodic replacement, researchers have begun investigating methods of generating energy from ambient sources. An airflow energy harvester for human motion is typically composed of a spring-mass system with an air pump connected in parallel with a spring and a turbine. Recent studies have proposed some airflow energy harvesting devices. However, these studies are focused on structural design and little attention has been devoted to the energy conversion process. There are two processes for energy conversion: human motion to airflow energy, then airflow energy to electricity. Focus on the energy conversion, this paper proposes a way to evaluate the energy of the airflow from the perspective of damping at harmonic excitations. The model of an airflow energy harvester for human motion composed of a spring-mass system with an air pump connected in parallel with a spring and a turbine is built, and the balance force analysis is carried out. Comparing the mathematical models and the force analysis equations, the regular pattern of the damping change of the system during the vibration is defined. The simulation isperformed, the result indicates that the energy of the airflow which the vibration system provides is related to the damping of the system. This paper provides a new method toanalyzethe energy conversion process, which helps to measure the efficiency of the airflow energy harvester preferably.

Exergy-based methods are powerful tools for developing, evaluating, understanding, and improving energy conversion systems. This paper deals with integrated advanced exergy-based evaluations. In addition to conventional methods, advanced exergy-based analyses consider (a) the interactions among components of the overall system, and (b) the real potential for improving each important system component. The main role of an advanced analysis is to provide energy conversion system designers and operators with information useful for improving the design and operation of such systems. Splitting the exergy destruction, the capital investment cost, and the component-related environmental impact associated with each single component of an energy conversion system into endogenous/exogenous and avoidable/unavoidable parts and using a further splitting of the exogenous exergy destruction improves (a) our understanding of the processes that take place, and (b) the quality of the conclusions for improvement obtained from the analysis. This paper discusses the main features and some recent developments in the area of advanced exergy-based methods. Application of the method to a simple air refrigeration machine confirms the correctness of the approach.

Air pollution and increased CO2 concentration in atmosphere and other energy related issues caused a transformative shift in energy system which contributes to increased utilization of renewables as alternative to generate green energy carriers. The potential of renewable resources in different region and potential energy conversion have been largely considered by many researcher in many countries. The energy conversion technologies to produce heat, electricity, and transportation fuels have made impressive technical advances. Sweden has also been challenging with mitigation of CO2 emission and trying to shift into a fossil fuel free system in all energy sectors. This paper deals with the current status of fuel demand and supply in the transport sector in a County in Sweden. A scenario for a fossil fuel free transport sector at a regional level is developed to investigate the potential biofuel production from regionally produced straw. The results and analysis indicate that the potential for cereal based bioethanol production in the region is sufficient to meet the biofuel demand of the County. Using the fallow land for cereal cultivation, it is feasible to shift into a fossil fuel free transportation system where all passenger cars are fueled by bioethanol. The results and finding from the current paper will be used to develop further study on optimization of local biofuel production integrated with CHP plants considering application of other feedstock such as municipal wastes.

This paper studies the multidisciplinary nature of two body wave energy converters by a parametric study based on the Taguchi method which helps to understand the effect of different dependent parameters on the wave energy conversion performance. Seven different parameters are analyzed and their effect on the maximum captured power, resonance frequency and bandwidth is studied. An interesting comparison between a cylindrical submerged body and a spherical one was made in terms of the system's viscous damping and hydrodynamics. The best system parameter combinations based on the maximum output power, best resonant frequency and frequency bandwidth were identified from the outcomes of the Taguchi method and optimized to capture the maximum power to operate in the specific (Australian) sea regions where the waves' frequencies are relatively low. This paper should provide a guideline for designers to tune their parameters based on the desired performance and sea state.

This paper presents results from a series of numerical modeling tests conducted with the objective of developing a computational framework for studying rock burst events. A commercially available distinct element code with its explicit time-stepping scheme is adopted for modeling the initial quasi-static and the subsequent dynamic response of rock burst in compression and shear. Ground reaction curves are introduced to discuss criteria for stability of a failure through stress analyses. Energy balance equations are analyzed for assessing the rock burst intensity by estimating radiated seismic energy once conditions of instability emerge. Two methods are discussed for estimating radiated seismic energy: tracking of the energy conversion during failure; recording the kinetic energy that is damped by mechanical damping schemes. Modeling approach and methodologies for studying compressive-type rock burst are developed and calibrated against available analytical solutions with respect to radiated seismic energy and excavation convergence. Factors participating in the intensity of rock burst in compression are examined by modeling a rectangular tabular excavation supported by a single pillar with ductile, semi-brittle, and brittle failure responses under different compressive loading . A shear-type rock burst along a strike-slip fault model is simulated and modeling approach is calibrated by checking the resulting slip distribution, radiated seismic energy, and seismic moment against analytical solutions. Factors contributing to the occurrence and intensity of shear-type rock burst are explored by simulating different slip scenarios under different loading conditions. With presented analyses, this paper provides a computational framework calibrated for studying rock burst events and, as a reference for treatment of more complex cases, shows how Young's modulus of the rock, failure stress drop, rock brittleness , and slip-weakening behaviors of faults govern the rock burst occurrence and intensity.

This paper constructed an energy configuration model with economic optimization in distributed energy system. On this basis, we carried out the sensitivity analysis of the price of large power grid, natural gas, cooling, heating and secondary power for the economic optimized results. And then, we have analyzed the critical value point of new energy conversion technologies appear or old disappear with the change of those energy price. In this paper, the secondary power price is same with the price of large power grid. In this study, an economic analysis of a distributed energy station project has been completed, which is a commercial complex in Shanghai. The results show that the power price have a biggest impact to -F value, and the influence of heating price is minimum, and supposing that self-generating electricity is grid-connected with no power injection. And at last, we find that the energy conversion technologies appear in different place of different scenario.

Energy is the blood of modern society and energy system plays an increasingly important role in urban development, especially in the background of a new round of energy reform. The construction of a new-generation of urban energy systems is becoming an important breakthrough to solve the bottleneck of urban development and to improve the quality of urban development in the future. From the perspective of the relationship between energy and cities, this paper analyzes the current situation and existing problems of urban energy system. Taking the research of energy system in Xiong’an New District as an opportunity, this paper explores the operation structure and implementation path of the new-generation urban energy system in Xiong’an New District. In this paper, it is considered that the new-generation energy system in Xiong’an New District will be electricity-centered, smart grid as the platform, energy transregional transmission combined with local development, optimal scheduling among multiple energy categories, and "source-grid-load-storage" high-efficiency interaction as well as the unified open market. The proposal of the new generation of urban energy system cannot only point out the direction for the planning and construction of the energy system in Xiong’an New District, but also help to solve the general problems in the urban energy system and promote the trend of energy transformation.

This paper investigates residential rooftop photovoltaic (PV) systems for long-term thermoeconomic benefits from PV homeowners’ perspectives and for impacts on the electrical distribution network from grid operators’ perspectives. The costs of generating electricity from grid-connected PV systems are studied with and without energy storage at the PV homeowners’ sites. Three selling scenarios for excess PV energy conversion are considered: net metering, wholesale pricing, and no payback. PV systems in Utah are utilized as case studies in this analysis. The presence of PV systems gives homeowners economic benefits such as reduced annual electricity bills. However, the levelized costs of electricity are considerably higher than the weighted electricity price in Utah. Currently, the addition of energy storage only benefits customers in Utah under the no payback policy. The impacts of PV systems toward electrical distribution networks are then studied on a distribution test system. Excess PV generation from residential PV systems causes voltage rise in the electrical distribution network. The results from this paper can educate consumers about the lifetime benefit of integrating solar energy into their homes. For grid operators, residential PV systems with energy storage can reduce the negative impacts on the grid compared with high PV penetration alone.

The integration of heat production from solar energy technologies can be realized by feeding in energy both at centralized or at multiple decentralized locations from the consumer side. As distribution networks serve as thermal transmission grids, the interaction between the energy feed in (i.e. production) and withdrawal (i.e. consumption) at multiple locations within distribution networks should be incorporated. Modelling the interactions between these subsystems is challenging. This paper aims to study the potential of district heating system with solar thermal based prosumers, by developing a modelling framework for design and simulation of such networks. Quantitative comparisons are made on the system performances, by addressing key technical configurations and constraints of thermal networks and temperature dynamics of energy sources. In this paper, a comprehensive design and simulation model is built to assess the performance of different scenarios of district heating system designs with solar thermal based prosumers. Design variations are carried out by selection of different buildings in the district as prosumers. The simulation model framework is setup in Matlab, with hourly time step. The distribution network model is formulated as a thermal hydraulic model representing detailed information on thermal and hydraulic losses on each pipe. It enables bidirectional flow from multiple sources integrated into the district heating network. Energy conversion technologies (solar thermal collectors) and heat demand are connected with the network model as source and sink. A natural gas boiler acts as an additional base load heat source. The design and simulation framework is applied to an artificial case study, composed of 20 buildings with mixed building stocks including office and residential buildings.

This paper deals with a development cycle and virtual prototyping of energy harvesting systems for industrial applications. Presented energy harvesting systems are an interesting alternative for autonomous powering of ultra-low power electronics, wireless sensors, condition reporting systems and structural monitoring systems. Energy harvesting systems could be able to convert an ambient energy to electricity and thus provide an autonomous power supply for mentioned applications without the need for batteries or wiring. Mechanical and thermal energy are promising autonomous sources of electricity mainly in aeronautics. Due to the recent development of the ultra-low power electronics wireless sensors they could be also embedded within machines, buildings and structures. The automatic collection of the measured information will be forwarded for the monitoring system. The power consumption of modern electronics is dropping, and the energy harvesting sources are starting to be a feasible energy solution in specific industrial applications. However, the amount of harvested energy is still quite small. Regarding that fact, the output electrical power must be predicted and compared with the power requirements of the intended electronics. This paper presents useful simulation tools for the prediction of harvested power under industrial operation, which consist of mathematical and simulation models of such multidisciplinary devices and experimental input data of ambient energy. The designed virtual prototypes include mathematical models of energy conversion, physical laws, multi-physical feedbacks, geometry, electronics, etc. Such virtual models are necessary for the development of new autonomous systems for industrial applications. Otherwise energy harvesting systems based on new smart materials and structures that could be integrated in the presented models for the future development of IoT applications.