The Effect of Reaction Temperature, Catalyst Concentration and Alcohol Ratio in the Production of Biodiesel from Raw and Purified Castor Oil

In this study, a homogeneous alkaline catalyst was used in the production of biodiesel from raw and refined castor oil feedstock. The effect of potassium hydroxide (KOH) as a catalyst between the two feedstocks, raw and refined castor oil was compared. The transesterification technique was utilized in this study, aiming to investigate the effect of different parameters, which include the reaction temperature, methanol-to-oil mole ratio, and catalyst concentration at a constant period of 90 minutes. The result revealed the performance of the KOH catalyst on raw castor oil yielded 98.49% FAME, which was higher than the refined castor oil which yielded 97.9% FAME. The optimal conditions obtained from refined castor oil were applied to raw castor oil because of the same properties. The fuel quality of castor oil and produced biodiesel were tested for physicochemical properties.

Hydrogen production at intermediate temperatures with proton conducting ceramic cells:Electrocatalytic activity,durability and energy efficiency

Proton conducting ceramic cells(PCCs)are an attractive emerging technology operating in the intermediate temperature range of 500 to 700℃.In this work,we evaluate the production of hydrogen at intermediate temperatures by proton conducting ceramic cell electrolysis(PCCEL).We demonstrate a highperformance steam electrolysis owing to a composite positrode based on BaGd_(0.8)La_(0.2)Co_(2)O_(6-δ)(BGLC1082)and BaZr0.5Ce0.4Y0.1O3-δ(BZCY541).The high reliability of PCCEL is demonstrated for 1680 h at a current density as high as-0.8 A cm^(-2)close to the thermoneutral cell voltage at 600℃.The electrolysis cell showed a specific energy consumption ranging from 54 to 66 kW h kg^(-1)that is comparable to state-of-the-art low temperature electrolysis technologies,while showing hydrogen production rates systematically higher than commercial solid oxide ceramic cells(SOCs).Compared to SOCs,the results verified the higher performances of PCCs at the relevant operating temperatures,due to the lower activation energy for proton transfer comparing with oxygen ion conduction.However,because of the p-type electronic conduction in protonic ceramics,the energy conversion rate of PCCs is relatively lower in steam electrolysis.The faradaic efficiency of the PCC in electrolysis mode can be increased at lower operating temperatures and in endothermic conditions,making PCCEL a technology of choice to valorize high temperature waste heat from industrial processes into hydrogen.To increase the faradaic efficiency by optimizing the materials,the cell design,or the operating strategy is a key challenge to address for future developments of PCCEL in order to achieve even more superior techno-economic merits.

Effect of Temperature on Extraction of Castor Oil from Castor Seeds Using Potential Green Solvents

Extraction of castor oil from castor seeds was investigated using different green solvents which include d-limonene, p-cymene, α-pinene, ethanol, and furfural at the temperature range of (323 - 413) K. The Soxhlet extraction method was employed to investigate the effect of temperature at atmospheric pressure. The focus of the study was to investigate a potential green solvent that can produce the high yields compared to the traditional solvent (hexane). The results show that at the average time of 3 hours and 30 minutes, the castor oil yield for green solvents were ranked as furfural (47.13%) > ethanol (45.37%) > p-cymene (39.15%) > d-limonene (39.13%) > α-pinene (38.11%). These castor oil yields were obtained at optimum temperatures for each green solvent. The castor oil yields were compared to the yield of hexane (31.36%) at same average time. The green solvents were recovered by using simple distillation, except furfural which was difficult to be recovered.

Progress in Research and Development of Molten Chloride Salt Technology for Next Generation Concentrated Solar Power Plants

Concentrated solar power(CSP)plants with thermal energy storage(TES)system are emerging as one kind of the most promising power plants in the future renewable energy system,since they can supply dispatchable and low-cost electricity with abundant but intermittent solar energy.In order to significantly reduce the levelized cost of electricity(LCOE)of the present commercial CSP plants,the next generation CSP technology with higher process temperature and energy efficiency is being developed.The TES system in the next generation CSP plants works with new TES materials at higher temperatures(>565℃)compared to that with the commercial nitrate salt mixtures.This paper reviews recent progressin research and development of the next generation CSP and TES technology.Emphasis is given on theadvanced'TES technology based on molten chloride salt mixtures such as MgCl_(2)/NaCl/KCl which hassimilar thermo-physical properties as the commercial nitrate salt mixtures,higher thermal stability(>800℃),and lower costs(<0.35USD·kg^(-1)).Recent progress in the selection/optimization of chloridesalts,determination of molten chloride salt properties,and corrosion control of construction materials(eg.,alloys)in molten chlorides is reviewed.

Optical Resolution of DL-Tartaric Acid Mediated by Diastereomeric Salts Crystallization: A Useful Method for Exploring and Optimizing Experimental Conditions

A response surface modeling approach for simultaneous optimization of optical purity and yield was applied to the resolution of tartaric acid to study the effects of both the amount of the solvent and the amount of the resolving agent a-methylbenzyl amine on the resolution results. The direction of changing the experimental conditions was determined from the initial response study, and expected high yield of the pure L(+)-tartaric acid-L(-)-a-methylbenzyl amine salt was obtained.

Thermodynamic and transport properties of spiro-(1,1')-bipyrrolidinium tetrafluoroborate and acetonitrile mixtures:A molecular dynamics study

Organic salts such as spiro-（1,1’）-bipyrrolidinium tetrafluoroborate（[SBP][BF4]） dissolved in liquid acetonitrile（ACN） are a new kind of organic salt solution,which is expected to be used as an electrolyte in electrical double layer capacitors（EDLCs）.To explore the physicochemical properties of the solution,an all-atom force field is established on the basis of AMBER parameter values and quantum mechanical calculations.Molecular dynamics（MD） simulations are carried out to explore the liquid structure and physicochemical properties of [SBP][BF4] electrolyte at room temperature.The computed thermodynamic and transport properties match the available experimental results very well.The microscopic structures of [SBP][BF4] salt solution are also discussed in detail.The method used in this work provides an efficient way of predicting the properties of organic salt solvent as an electrolyte in EDLCs.

PHASE EQUILIBRIUM OF COMPLEX MIXTURES WITH EQUATIONS OF STATE: AN UPDATE5

Here we review a new class of mixing rules (hat have extended range of mixtures and conditions that can now be described by equation of state models. One characteristic of these mixing rules is that they simultaneously satisfy the boundary conditions of producing a second virial coefficient that is quadratic in mole fraction, and a free energy of mixing like that of an activity coefficient model at high density, though the mixing rule is itself independent of density. We show that using this mixing rule, various asymmetric, highly nonideal mixtures can be accurately described. One serendipitous result is that the parameters in this mixing rule model are almost independent of temperature, which allows accurate extrapolations of phase behavior to be made over large ranges of temperature and pressure.

Modeling and Validation of the Ice Growth in an Ice Storage System

This work deals with the optimization of the icing process in an ice storage system.It is focused on the improvement of the icing behavior,which is to be achieved by different heat exchanger geometries in the ice storage tank.Therefore,CFD simulations were implemented to acquire and visualize the flow conditions,the temperature behavior and the growth of the ice layer during the cooling process.The results are compared and validated with model experiments on an experimental ice storage.It could be shown that the heat extraction of current technologies can be increased by more than 50% by using geometries that are more efficient.

Degradation study on tin- and bismuth-based gas-diffusion electrodes during electrochemical CO_(2) reduction in highly alkaline media

This work investigated the degradation of tin – based gas-diffusion electrodes (GDE) and also a promising Bi2O3 GDE in electrochemical CO_(2) reduction in highly alkaline media which has not been studied before. The contributions of the electrode wetting (or flooding, if excessively) and catalyst leaching on the degradation were analyzed. Therefore, electrochemical impedance spectroscopy was used to monitor the wetted surface area of the GDE in combination with post-mortem analysis of the penetration depth by visualizing the electrolyte’s cation in the GDE cross-section. Furthermore, to reveal a possible degradation of the electrocatalyst, its distribution was mapped in the GDEs cross-section after operation while the catholyte was additionally analyzed via ICP-MS. The results clearly demonstrate that the SnO_(2) catalyst dissolves in the reaction zone inside the GDE and might be partially redeposited near the GDEs surface. Since the redeposition process occurs only partially a steady loss of catalyst was observed impeding a clear distinction of the two degradation phenomena. Nevertheless, the deterioration of the electrode performance measured as faraday efficiency (FE) of the parasitic hydrogen evolution reaction (HER) qualitatively correlates with the differential double layer capacitance (Cdl). A significant difference of the rate of increase for the hydrogen FE and Cdl can be ascribed to the superposition of both above-mentioned degradation mechanisms. The demonstrated instability of SnO_(2) contrasts with the behavior of Bi2O3 GDE which is stabilized during CO_(2) conversion by redeposition of the diluted dissolved species as metallic Bi which is active for the CO_(2) reduction reaction.

Special issue on progress in advanced energy technologies and materials

This special issue of the Chinese Journal of Chemical Engineering(CJCh E)concerns with the current progress in advanced energy technologies and materials related to chemical science and technology,especially the work in the field of renewable energy,energy storage,clean and efficient utilization of energy,aligning well to the scope of this Journal.The world is moving towards a sustainable,clean and low-carbon future via‘Energy Transition',i.e..

Influence of velocity profile on calibration function of Lorentz force flowmeter

A Lorentz force flowmeter is a noncontact electromagnetic flow-measuring device based on exposing a flowing electrically conducting liquid to a magnetic field and measuring the force acting on the magnet system. The measured Lorentz force is proportional to the flow rate via a calibration coefficient which depends on the velocity distribution and magnetic field in liquid. In this paper, the influence of different velocity profiles on the calibration coefficient is investigated by using numerical simulations. The Lorentz forces are computed for laminar flows in closed and open rectangular channels, and the results are compared with the simplified case of a solid conductor moving at a constant velocity. The numerical computations demonstrate that calibration coefficients for solid bodies are always higher than for liquid metals. Moreover, it can be found that for some parameters the solid-body calibration coefficient is almost twice as high as for a liquid metal. These differences are explained by analyzing the patterns of the induced eddy currents and the spatial distributions of the Lorentz force density. The result provides a first step for evaluating the influence of the laminar velocity profiles on the calibration function of a Lorentz force flowmeter.

Numerical Analysis of the Thermal Behavior of a Hermetic Reciprocating Compressor

A numerical model to predict the temperature field in a hermetic reciprocating compressor for household refrigeration appliances is presented in this work. The model combines a high resolution three-dimensional heat conduction formulation of the compressor＇s solid parts, a three-dimensional CFD （computational fluid dynamics） approach for the gas line domain and lumped formulations of the shell gas and the lubrication oil. Heat transfer coefficients are determined by applying CFD to the gas line side and correlations from the literature on the shell gas and oil side, respectively. The valve in the gas line simulation is modelled as a parallel moving fiat plate. By means of an iterative loop the temperature field of the solid parts acts as boundary condition for the CFD calculation of the gas line which returns a cycle averaged quantity of heat to the solid parts. Using an iteration method which is based on the temperature deviation between two iteration steps, the total number of iterations and consequently the computational time can be reduced. The loop is continued until a steady-state temperature field is obtained. Calculated temperatures of the solid parts are verified by temperature measurements of a calorimeter test bench.

Thermal Energy Storage Systems： Power-to-Heat Concepts in Solid Media Storage for High Storage Densities

The German Aerospace Center has merged a wide range of technological research and development for future cars in a project called ＂Next Generation Car＂. Within this large research project, three vehicle concepts for different applications （urban, regional and interurban） and with different powertrains （fuel-cell, battery and hybrid） will be developed. Research questions on different levels from conceptual question about vehicle modularity down to detailed technological aspects like combining hydrogen storage with cabin climatization and a systematic investigation of different thermal energy storage systems for electric vehicles concepts are covered by this project. To the latter, the contribution shows an overview about three thermal storage technologies--sensible solid media, metallic latent and thermochemical thermal energy storage systems--and details about the development of an electrically heated （power-to-heat） solid media storage system to achieve high storage densities and to allow flexible thermal discharging values. Central works target the identification of suitable thermal management solutions in future electric vehicle concepts to increase range, efficiency and flexibility.

Single-pulse real-time billion-frames-per-second planar imaging of ultrafast nanoparticle-laser dynamics and temperature in flames

Unburnt hydrocarbon flames produce soot,which is the second biggest contributor to global warming and harmful to human health.The state-of-the-art high-speed imaging techniques,developed to study non-repeatable turbulent flames,are limited to million-frames-per-second imaging rates,falling short in capturing the dynamics of critical species.Unfortunately,these techniques do not provide a complete picture of flame-laser interactions,important for understanding soot formation.Furthermore,thermal effects induced by multiple consecutive pulses modify the optical properties of soot nanoparticles,thus making single-pulse imaging essential.Here,we report single-shot laser-sheet compressed ultrafast photography(LS-CUP)for billion-frames-per-second planar imaging of flame-laser dynamics.We observed laser-induced incandescence,elastic light scattering,and fluorescence of soot precursors-polycyclic aromatic hydrocarbons(PAHs)in real-time using a single nanosecond laser pulse.The spatiotemporal maps of the PAHs emission,soot temperature,primary nanoparticle size,soot aggregate size,and the number of monomers,present strong experimental evidence in support of the theory and modeling of soot inception and growth mechanism in flames.LS-CUP represents a generic and indispensable tool that combines a portfolio of ultrafast combustion diagnostic techniques,covering the entire lifecycle of soot nanoparticles,for probing extremely short-lived(picoseconds to nanoseconds)species in the spatiotemporal domain in non-repeatable turbulent environments.Finally,LS-CUP’s unparalleled capability of ultrafast wide-field temperature imaging in real-time is envisioned to unravel mysteries in modern physics such as hot plasma, sonoluminescence, and nuclear fusion.

Corrosion behavior of Fe–Cr–Ni based alloys exposed to molten MgCl_(2)–KCl–NaCl salt with over-added Mg corrosion inhibitor

MgCl_(2)–NaCl–KCl salts mixture shows great potential as a high-temperature(>700°C)thermal energy storage material in next-generation concentrated solar power plants.Adding Mg into molten MgCl_(2)–NaCl–KCl salt as a corrosion inhibitor is one of the most effective and cost-effective methods to mitigate the molten salt corrosion of commercial Fe–Cr–Ni alloys.However,it is found in this work that both stainless steel 310 and Incoloy 800H samples were severely corroded after 500 h immersion test at 700°C when the alloy samples directly contacted with the over-added Mg in the liquid form.The corrosion attack is different from the classical impurity-driven corrosion in molten chloride salts found in previous work.Microscopic analysis indicates that Ni preferentially leaches out of alloy matrix due to the tendency to form MgNi_(2)/Mg_(2)Ni compounds.The Ni-depletion leads to the formation of a porous corrosion layer on both alloys,with the thickness around 204μm(stainless steel 310)and 1300μm(Incoloy 800H),respectively.These results suggest that direct contact of liquid Mg with Ni-containing alloys should be avoided during using Mg as a corrosion inhibitor for MgCl_(2)–NaCl–KCl or other chlorides for high temperature heat storage and transfer.

Molecular dynamics simulation of the Stribeck curve: Boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level

Lubricated contact processes are studied using classical molecular dynamics simulations for determining the entire range of the Stribeck curve.Therefore,the lateral movement of two solid bodies at different gap height are studied.In each simulation,a rigid asperity is moved at constant height above a flat iron surface in a lubricating fluid.Both methane and decane are considered as lubricants.The three main lubrication regimes of the Stribeck curve and their transition regions are covered by the study:Boundary lubrication(significant elastic and plastic deformation of the substrate),mixed lubrication(adsorbed fluid layer dominates the process),and hydrodynamic lubrication(shear flow is set up between the surface and the asperity).We find the formation of a tribofilm in which lubricant molecules are immersed into the metal surface—not only in the case of scratching,but also for boundary lubrication and mixed lubrication.The formation of a tribofilm is found to have important consequences for the contact process.Moreover,the two fluids are found to show distinctly different behavior in the three lubrication regimes:For hydrodynamic lubrication(large gap height),decane yields a better tribological performance;for boundary lubrication(small gap height),decane shows a larger friction coefficient than methane,which is due to the different mechanisms observed for the formation of the tribofilm;the mixed lubrication regime can be considered as a transition regime between the two other regimes.Moreover,it is found that the nature of the tribofilm depends on the lubricant:While methane particles substitute substrate atoms sustaining mostly the crystalline structure,the decane molecules distort the substrate surface and an amorphous tribofilm is formed.

Corrosion behavior of metallic alloys in molten chloride salts for thermal energy storage in concentrated solar power plants： A review

Recently, more and more attention is paid on applications of molten chlorides in concentrated solar power （CSP） plants as high-temperature thermal energy storage （TES） and heat transfer fluid （HTF） materials due to their high thermal stability limits and low prices, compared to the commercial TES/HTF materials in CSP- nitrate salt mixtures. A higher TES/HTF operating temperature leads to higher efficiency of thermal to electrical energy conversion of the power block in CSP, however causes additional challenges, particularly increased corrosiveness of metallic alloys used as contain- ers and structural materials. Thus, it is essential to study corrosion behaviors and mechanisms of metallic alloys in molten chlorides at operating temperatures （500-800℃） for realizing the commercial application of molten chlorides in CSE The results of studies on hot corrosion of metallic alloys in molten chlorides are reviewed to understand their corrosion behaviors and mechanisms under various conditions （e.g., temperature, atmosphere）. Emphasis has also been given on salt purification to reduce corrosive impurities in molten chlorides and development of electrochemical techniques to in-situ monitor corrosive impurities in molten chlorides, in order to efficiently control corrosion rates of metallic alloys in molten chlorides to meet the requirements of industrial applications.

Simulation study on dynamics of A- to B-form transition in aqueous DNA solution:Effect of alkali metal counterions

DNA and its conformational transition can be used to design nanometer-scale structures, nano-tweezers and nanomechanical devices. Experiments and molecular simulations have been used to study the concentration effect on the A-DNA→B-DNA conformational transition, but a systematical investigation on counterion effect on the dynamics of this transition has not been reported up to now. In present work, restrained and unrestrained molecular dynamics （MD） simulations have been performed to characterize the stability of DNA conformations and the dynamics of A-DNA→B-DNA transitions in aqueous solutions with different alkali metal counterions. The DNA duplex d（CGCGAATTCGCG）2, coion Cl- and counterions Li＋, Na＋, K＋, Rb＋ and Cs~ as well as water molecule were considered using the PARM99 force field in the AMBER8 package. It was found that B-form DNA is more stable than A-form DNA in aqueous electrolyte solutions with different alkali metal counterions. In- creasing KCI concentration in solution hinders the A-DNA^B-DNA transition and the transition times for different alkali metal counterions conform to neither the simple sequence related to naked ion size nor to hydrated diameter, but an apparently abnormal sequence of K＋ 〈 Rb＋ 〈 Cs＋ 〈 Na＋ 〈 Li＋. This abnormal sequence can be well understood in terms of an electrostatic model based on the effective cation diameters and the modified mean-spherical approximation （MMSA）. The present results provide valuable information for the design of DNA-based nanomaterials and nanodevices.

Molecular dynamics simulation of the A-DNA to B-DNA transition in aqueous RbCl solution

Unrestrained molecular dynamics （MD） simulations have been carded out to characterize the stability of DNA conformations and the dynamics of A-DNA^B-DNA conformational transitions in aqueous RbC1 solutions. The PARM99 force field in the AMBER8 package was used to investigate the effect of RbC1 concentration on the dynamics of the A^B conformational tran- sition in the DNA duplex d（CGCGAATTCGCG）2. Canonical A- and B-form DNA were assumed for the initial conformation and the final conformation had a length per complete turn that matched the canonical B-DNA. The DNA structure was moni- tored for 3.0 ns and the distances between the C5＇ atoms were obtained from the simulations. It was found that all of the double stranded DNA strands of A-DNA converged to the structure of B-form DNA within 1.0 ns during the unrestrained MD simula- tions. In addition, increasing the RbC1 concentration in aqueous solution hindered the A^B conformational transition and the transition in aqueous RbC1 solution was faster than that in aqueous NaC1 solution for the same electrolyte strength. The effects of the types and concentrations of counterions on the dynamics of the A^B conformational transition can be understood in terms of the variation in water activity and the number of accumulated counterions in the major grooves of A-DNA. The ru- bidium ion distributions around both fixed A-DNA and B-DNA were obtained using the restrained MD simulations to help ex- plain the effect of RbC1 concentration on the dynamics of the A^B conformational transition.

Facilitating Water electrolysers for electricity-grid services in Europe through establishing standardized testing protocols

Electrolysers,which convert electricity into hydrogen,have the potential to offer a variety of electrical-grid services,therefore facilitating the integration of intermittent renewables into electrical grids.Among various activities that aim to unlock this hidden value,the 3-year European Union project QualyGridS launched in 2017 aims to establish standardized testing protocols for electrolysers to perform electricity-grid services.This paper shares experience and intermediate results of QualyGridS with respect to the testing protocols,test benches and testing results.The results of this work facilitate mutual understanding between the electricity industry and the hydrogen industry,support further development of the cross-sector testing standards,guide the design and selection of grid-service-oriented electrolyser applications and foster the transition towards a fossil-free-energy future based on high shares of hydrogen and other renewable solutions.