Energy hub-based optimal planning for integrated energy systems considering part-load characteristics and synergistic effect of equipment

Integrated energy systems(lESs)represent a promising energy supply model within the energy internet.However,multi-energy flow coupling in the optimal configuration of IES results in a series of simplifications in the preliminary planning,affecting the cost,efficiency,and environmental performance of IES.A novel optimal planning method that considers the part-load characteristics and spatio-temporal synergistic effects of IES components is proposed to enable a rational design of the structure and size of IES.An extended energy hub model is introduced based on the“node of energy hub”concept by decomposing the IES into different types of energy equipment.Subsequently,a planning method is applied as a two-level optimization framework-the upper level is used to identify the type and size of the component,while the bottom level is used to optimize the operation strategy based on a typical day analysis method.The planning problem is solved using a two-stage evolutionary algorithm,combing the multiple-mutations adaptive genetic algorithm with an interior point optimization solver,to minimize the lifetime cost of the IES.Finally,the feasibility of the proposed planning method is demonstrated using a case study.The life cycle costs of the IES with and without consideration of the part-load characteristics of the components were$4.26 million and$4.15 million,respectively,in the case study.Moreover,ignoring the variation in component characteristics in the design stage resulted in an additional 11.57%expenditure due to an energy efficiency reduction under the off-design conditions.

Structural,optical properties and optical modelling of hydrothermal chemical growth derived Zn O nanowires

Zn O nanowire films were produced at 90°C using a hydrothermal chemical deposition method,and were characterised with scanning electron microscopy,optical transmission spectrometry and X-ray diffraction.The results showed that the optical band gap is 3.274-3.347 e V.Film porosity and microstructure can be controlled by adjusting the p H of the growth solution.Zn O nanowire films comprise a 2-layer structure as demonstrated by SEM analysis,showing different porosities for each layer.XRD analysis shows preferential growth in the(002)orientation.A comprehensive optical modelling method for nanostructured Zn O thin films was proposed,consisting of Bruggeman effective medium approximations,rough surface light scattering and O’Leary-Johnson-Lim models.Fitted optical transmission of nanostructured Zn O films agreed well with experimental data.

Improving supercritical water gasification of sludge by oil palm empty fruit bunch addition: Promotion of syngas production and heavy metal stabilization

The co-gasification of sewage sludge and palm oil empty fruit bunch(EFB) in supercritical water(SCW) was conducted at 400 °C with a pressure of over 25 MPa. This study aimed to investigate the influence of EFB addition on the syngas production and its composition. The heavy metal distribution and the leaching potential of the solid residue were also assessed. The results showed that syngas yield significantly increased with the addition of EFB into the feedstock. The cold gas efficiency(CGE) and carbon efficiency(CE) of co-gasification were higher than those of individual gasification. The actual syngas production from co-gasification of sludge and EFB was 45% higher than the theoretical total volume. The results indicated that the addition of EFB to sludge had the synergetic promotion effect on syngas production from sludge and EFB in supercritical water. This enhancement might be due to the dissolution of alkali metals from EFB and the adjustment of organic ratio. In addition, higher percentage of heavy metals were deposited and stabilized in the solid residue after SCWG. The leaching concentration of heavy metals from the solid residues was decreased to a level below the standard limit which enables it to be safely disposed of in landfill. In conclusion, the EFB addition has been proved to promote syngas production,as well as, stabilize the heavy metal in solid residues during co-SCWG.

Dynamic behavior of a rotating gliding arc plasma in nitrogen:effects of gas flow rate and operating current

The effects of feed gas flow rate and operating current on the electrical characteristics and dynamic behavior of a rotating gliding arc （RGA） plasma codriven by a magnetic field and tangential flow were investigated.The operating current has been shown to significantly affect the time-resolved voltage waveforms of the discharge,particularly at flow rate =21 min^-1.When the current was lower than 140 mA,sinusoidal waveforms with regular variation periods of 13.5-17.0 ms can be observed （flow rate =21 min^-1）.The restrike mode characterized by serial sudden drops of voltage appeared under all studied conditions.Increasing the flow rate from 8 to 121 min^-1 （at the same current） led to a shift of arc rotation mode which would then result in a significant drop of discharge voltage （around 120-200 V）.For a given flow rate,the reduction of current resulted in a nearly linear increase of voltage.

Experimental and modeling study on dust cake profile and its influence on pressure drop in fiber filter

Alumina （MMAD： 32.45μm） was used to study dust cake formation in fiber filter at steady-state operation. Cake vertical profile along filter medium versus filtration velocity （ranging from 3 to 7cm/s）, particle concentration （ranging from 40 to 120g/m^3） and particle areal mass to filter （ranging from 0.57 to 2.86 kg/m^2）, was researched by experiments and modeling. The filtration was carried through by a plane filter media （Material： Terylene felt, Thickness： 1.8mm） covered on a framework which was fixed in a filter. During filtration, the cake thickness was measured up and down by a mobile microscope and a camera controlled by a PC. The results showed that the cake vertical profile accord with a peak function. The peak amplitude A, center displacement xc, the shape parameters W of the peak function was greatly depended on filtration velocity and particle areal mass to filter, whereas slightly on particle concentration. The relationships between the three coefficients （peak amplitude A, center displacement xc, the shape parameters W） and filtration velocity, areal mass to filter, particle concentration were associated as equations, based on which pressure drop model was deduced. The peak function and pressure drop model were verified with experimental data.

Crystal,Thermal Behavior and Electrochemical Property of Dichloro-tri(N-ethylimidazole)-cadmium

The title compound Cd（Eim）3Cl2 （Eim = N-ethylimidazole） I has been synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2 1 with a = 8.0460（16）, b = 29.186（6）, c = 8.8960（18）A,β= 100.06（3）°, C15H24CdCl2N6, Mr = 471.71, V = 2056.9（7）A^3 Z = 4, Dc = 1.523 g/cm^3,/1 = 1.330 mm^-1, F（000） = 952, the final R = 0.0455 and wR = 0.0723. The title compound crystallizes with two molecules in the asymmetric unit. Each Cd^II ion is coordinated by three Eim ligands and two Cl anions in a trigonal bipyramidal geometry in two molecules. The weak intermolecular C-H……Cl hydrogen bonds link the molecules into two independent hydrogen-bonded chains running along the c axis. According to the cyclic voltammogram measurement in H2O, the electrode reaction should be a quasi-reversible process.

Synthesis and Crystal Structure of Tetrakis(1-vinylimidazole-kN^3)diisothiocyanatomanganese(II)

The title compound I （C22H24MnN10S2, Mr = 547.57） has been synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2 1/c with a = 8.6010（17）, b = 9.0180（18）, c = 17.773（4）A, β = 101.79（3）°, V = 1349.5（5）A^3, Z = 2, Dc = 1.348 g/cm^3,/1 = 0.674 mm^-1, F（000） = 566, the final R = 0.0488 and wR = 0.1289. In the structure, each Mn atom is coordinated by four Vim （Vim = 1-vinylimidazole） ligands and a pair of monodentate isothioeyanic groups, affording a compressed oetahedral MnN6 core.

Dynamic Model and Performance of Absorption Heat Pump in Shut-down Process

The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure generator and heat exchanger are analyzed in detail. The proper shut-down mode of the heat pump is presented,which, in consideration of solution parameters, has a great effect on the possibility of crystallization of some components.

Correction to:Utilization of molten chloride salt derived from MSWI fly ash washing as energy storage material:thermophysical properties and corrosion behavior

Correction to:Waste Disposal&Sustainable Energy(2022)4:193-203 https:/doi.0rg/10.1007/s42768-022-00110-6 The section‘Conflict of Interest'has been amended:‘Mi Yan is the Young Editorial Board member of Waste Disposal&Sustainable Energy.'The revised‘Conflict of Interest'is as follows:Mi Yan is the Young Editorial Board member of Waste Disposal&Sustainable Energy.The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

PERFORMANCE IMPROVEMENT OF CENTRIFUGAL FAN BY MEANS OF NUMERICAL SIMULATION

Numerical simulation is used to investigate the flow field in a model centrifugal fan for steam power stations in order to improve the performance. During testing the model fan, it is found that the efficiency is only 62.5% with inlet box, without it the efficiency is 83%. In addition, the strong vibration of test rig is observed with inlet box. It would be highly desirable if the aerodynamics of the fan could be studied. Therefore, numerical simulation is carried out to investigate the internal flow characteristics of a model fan with inlet box. The results from CFD analysis show that the whole region of the inlet box is occupied by a spiral vortex rotating inversely as the rotor＇s direction, which significantly affect the most flow＇region inside the fan. For this reason, a dummy plate is arranged in the inlet box to impede the generation of the spiral vortex, the results from CFD after the reform demonstrate that the modification is quiet effective, the former large spiral vertex has been destroyed effectively, the large one is superseded in favor of two small vortexes. However, two small vortexes have little effect on the inner flow of the rotor and the following parts. Finally, the efficiency of the model fan is improved by the test and the strong vibration of the test rig disappears. This type of modification has been used in steam power stations, the fan efficiency raises to 84% successfully.

Slagging characteristics of molten coal ash on silicon-aluminum combustion liners of boiler

In order to study the slagging characteristics of boiler combustion liners during pulverized coal stream combustion, the slag samples on the surface of combustion liner were investigated by X-ray diffractometry, scan electron microscopy and energy dispersive X-ray analysis, and the transformation characteristics of the compositions and crystal phases were studied. The results show that the size of slag granules decreases as the slagging temperature increases; the crystallinity of coal ash I reduces to about 48.6% when the temperature is increased up to 1 350 ℃, and that of the coal ash II reduces to about 65% when the temperature is increased up to 1 500 ℃; the encroachment of molten coal ash to the combustion liner is strengthened. At the same time, the diffusion and the segregation of the compositions in combustion liners have selectivity, which is in favor of enhancing the content of crystal phases, weakening the conglutination among molten slag compositions and combustion liner, and avoiding yielding big clinkers. But the diffusion of the compositions in combustion liners increases the porosity and decreases the mechanical intensity of combustion liner, and makes the slag encroachment to the liner become more serious.

The Characteristics of the Evaporator/Evaporator for Direct Expansion Solar Assisted Heat Pump System

Direct expansion solar assisted heat pump (DX-SAHP) technology is developed by combining solar energy heat utilization with heat pump energy saving technology. The experimental researches of the DX-SAHP hot water system are conducted in this paper, and overall performance of DX-SAHP is analyzed with three different structures of collectors/evaporators, namely a bare-plate collector, a glass-plate collector and double collectors/evaporators (a bare-plate collector and a glass-plate collector). The influence factors and overall performance are studied, which show that the overall performance of the system is mainly influenced by solar irradiation intensity and the collector area. Comparing with glass-plate collector in similar conditions, bare-plate collector system COP is higher. While increasing collector area is conducive to improve the system COP, but will reduce the collector efficiency and increase the workload of the compressor by comparing the bare-plate collector with double-plate collectors.

Phosphorus-enriched biochar from biogas residue of Eichhornia crassipes:transformation and release of phosphorus

Pyrolysis is an effective technology for treating and utilizing biogas residue.To explore the phosphorus(P)supply capacity of the biochar generated from biogas residue of Eichhornia Crassipes,the P speciation of E.crassipes biogas residue and biomass during pyrolysis(300-700℃)was analyzed by combining sequential chemical extraction,31P nuclear magnetic resonance(NMR)and P K-edge X-ray absorption near edge structure(XANES)spectroscopy.Pyrolysis treatment promoted the conversion of amorphous Ca-P phases in biogas residue and biomass into crystalline hydroxyapatite(HAP)phase,which matched the formation of stable HCl-P pools in the biochar derived from biogas residue(AEBs,22.65-82.04%)and biomass(EBs,13.08-33.52%)in the process of pyrolysis.Moreover,the total P contents in AEBs(19.43-28.92 mg g^(−1))were higher than that of EBs(3.41-5.26 mg g^(−1)),indicating that AEBs had a great P reclamation potential.The P release kinetics from AEBs and EBs in water were evaluated via an incubation experiment for 360 h.The P release from both AEBs and EBs conformed to the pseudo-second order kinetics model(R^(2)>0.93),but their P release behaviors were different.The P release of AEBs conformed to the diffusion-re-adsorption model,while that of EBs accorded with the diffusion-dissolution model.The diffusive gradients in thin-films(DGT)analysis showed that AEBs could significantly increase soil available P content as compared with EBs.Hence,the biochar produced from biogas residue of E.crassipes via pyrolysis has a good application potential as a P fertilizer.

Effect of Support Height on Microstructure and Mechanical Properties of Selective Laser Melting Ti-15Mo Alloy

In this research,for the first time,the Ti-15Mo alloy generated via selective laser melting(SLM)with many different support heights was examined.With the increase of the support height,the risks of forming microcracks and small holes increase while the ductility of the sample decreases.The grain sizes of the samples decrease with an increase in support height because of the more efficient heat dissipation rate during the SLM process.The average grain sizes of the samples are 36.95±0.7μm(5 mm-sample I),35.24±0.7μm(10 mm-sample II)and 33.91±0.7μm(15 mm-sample III),respectively.As the support height increases,the intensity of(111)texture increases and the misorientation angles gradually decrease.The ultimate tensile strength,yield strength and ductility of the three samples are 970±13 MPa,769±12 MPa and 9.78%±1.5%(sample I),1051±11 MPa,932±11 MPa and 7.17%±2%(sample II),1123±14 MPa,1089±9 MPa and 5.4%±1.4%(sample III),respectively.The decrease in grain size,increase in dislocation density and enhancement of the(111)texture are all conducive to achieving the higher strength.

Utilization of molten chloride salt derived from MSWI fly ash washing as energy storage material:thermophysical properties and corrosion behavior

Fly ash,as a byproduct of municipal solid waste incineration,contains several kinds of pollutants,especially dissolvable salts that cause a severe challenge for fly ash disposal.Washing combined with cement kiln co-processing for fly ash disposal has been applied in China.After washing,the wastewater was evaporated to produce fly ash salt(FAS).In this study,FAS was mixed the KCl and LiCl to be used as molten chloride salt for energy storage material.Twenty-three types of molten salts with various ratios of FAS-KCl-LiCl were evaluated.Thermophysical properties(melting point and latent heat)and thermal stability of these salts were characterized.The increase in FAS fraction decreased the latent heat of molten salts.Among the tested samples,the best compatibility ratio of FAS:KCl:LiCl was 10:50:40(%,in weight),with latent heat of 108.7 J/g and melting point of 333℃.This molten salt also showed good thermal stability after 1–13 h of thermal experiments,and the mass loss was less than 2%after 5 heating cycles at 600℃.By corrosion test,FAS-KCl-LiCl(10:50:40,%in weight)could be more safely used in vessels made of nickel-based alloy,but it might cause corrosion risk for stainless steel.

Effect of ammonium sulfate and urea on PCDD/F formation from active carbon and possible mechanism of inhibition

The effect of ammonium sulfate （（NH4）2SO4） and urea （CO（NH2）2） on polychlorinated dibenzo-p-dioxin and dibenzofuran （PCDD/F） formation from active carbon was investigated in this study. Both additives could significantly inhibit PCDD/F formation, and PCDD/F （TEQ） generation was reduced to 98.5% （98%） or 64.5% （77.2%） after 5% （NH4）2S04 or CO（NH2）2 was added into model ash, respectively. The inhibition efficiency of PCDDs was higher than the value of PCDFs, however, the reduction of PCDD/F yield was mainly from PCDFs decreasing. In addition, the solid-phase products were reduced more than the gas-phase compounds by inhibitors. By the measurement of chlorine emission in the phase of ion （Cl[Cl^-]） and molecule gas （Cl[Cl2]）, it was observed that both Cl[Cl^-] and Cl[Cl2] were reduced after inhibitors were added into ash. Cl[Cl2] was reduced to 51.0% by urea addition, which was supposed as one possible mechanism of PCDD/F inhibition.

Correction to:Treatment of wastewater from food waste hydrothermal carbonization via Fenton oxidization combined activated carbon adsorption

Correction to:Waste Disposal&Sustainable Energy(2022)4:205-218 https://doi.0rg/10.1007/s42768-022-00106-2 The section‘Conflict of Interest'has been amended:‘Mi Yan is the Young Editorial Board member of Waste Disposal&Sustainable Energy'.The revised'Conflict of Interest'is as follows:Mi Yan is the Young Editorial Board member of Waste Disposal&Sustainable Energy.

Pilot scale autothermal gasification of coconut shell with CO2-O2 mixture

This paper explored the feasibility and benefit of CO2 utilization as gasifying agent in the autothermal gasification process. The effects of CO2 injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO2/C ratio from 0.6 to 1.6. O2 was injected at an equivalence ratio of approximately 0.33-0.38 for supply- ing heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO2 injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO2-O2 gasification with a CO2/C ratio of 0.6-1.2. The progress of the expected CO2 to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO2/C ratio increased. The producer gas heating value of CO2-O2 gasification was consistently higher than that of air gasification. These results show the potential of CO2-O2 gasification for producing high qualityproducer gas in an efficient manner, and the necessity for more work to deeply imply the observation.

Treatment of wastewater from food waste hydrothermal carbonization via Fenton oxidization combined activated carbon adsorption

Hydrothermal carbonization(HTC)of food waste can produce hydrochar for further utilization as high-quality fuel or carbon materials,but the by-product of liquid effluent,named HTC wastewater,has a high chemical oxygen demand(COD)content and other organic pollutants.This study focused on the feasibility of Fenton oxidation combined with activated carbon(AC)to reduce COD in HTC wastewater.The effects of different parameters including pH,dosage of hydrogen peroxide,molar ratio of Fe^(2+)/H_(2)O_(2),and reaction time were tested and discussed.Eventually,through the optimized Fenton oxidation(pH=3,H_(2)O_(2)dosage=1.5 mol/L,Fe^(2+)/H_(2)O_(2)=1:15,reaction time=60 min)combined optimized AC adsorption process(AC dosage=30 g/L),the COD value reduced from 42,000 mg/L to 3075 mg/L,indicating a COD removal efficiency of 92.7%and a color removal ratio of 91.9%,respectively.The comparison of GC/MS(gas chromatography mass spectrometer)and FTIR(Fourier transform infrared spectrometer)of liquid residual from different treatment methods also indicated that the types of organic substances in HTC wastewater were significantly reduced through Fenton oxidation and AC adsorption.

Investigation on nonlinear thermo-acoustic characteristics of Rijke tube

Based on the energy conservation relationship, nonlinear thermo-acoustic effects of Rijke tube including instability range, saturation processes and higher harmonics modes were investigated. With coupling between the external flow and the inner space of a Rijke tube, the acoustic characteristics of self-excited oscillation were simulated. The experimental study was also carried out and the results were compared with those from simulation. The nonlinear factors which distort the acoustic waveform distortion were analyzed. From the results, it is seen that varying size of the nozzle outlet changes the acoustic impedance in the boundary, and leads to reduction of the nonlinear effects. The results show that the modes of self-excited oscillation could be influenced by the position of higher harmonics. In the large amplitude oscillation, the distortion of pressure wave within Rijke tube could be induced by the acoustic losses due to vortices on nozzle. It is found that the waveform distortion could be avoided by the shrinkage of nozzle.