thermodynamics

摘要： MgH_(2)with a large hydrogen capacity is regarded as a promising hydrogen storage material.However,it still suffers from high thermal stability and sluggish kinetics.In this paper,highly dispersed nano-Ni has been successfully prepared by using the polyol reduction method with an average size of 2.14 nm,which significantly improves the de/rehydrogenation properties of MgH_(2).The MgH_(2)–10wt%nano-Ni sample starts releasing H_(2)at 497 K,and roughly 6.2wt%H_(2)has been liberated at 583 K.The rehydrogenation kinetics of the sample are also greatly improved,and the adsorption capacity reaches 5.3wt%H_(2)in 1000 s at 482 K and under 3 MPa hydrogen pressure.Moreover,the activation energies of de/rehydrogenation of the MgH_(2)–10wt%nano-Ni sample are reduced to(88±2)and(87±1)kJ·mol−1,respectively.In addition,the thermal stability of the MgH_(2)–10wt%nano-Ni system is reduced by 5.5 kJ per mol H_(2)from that of pristine MgH_(2).This finding indicates that nano-Ni significantly improves both the thermodynamic and kinetic performances of the de/rehydrogenation of MgH_(2),serving as a bi-functional additive of both reagent and catalyst.

摘要： James Watt contributed significantly to the development of the thermodynamics of energy conversion as a science. Several of his ideas are now integral part of thermodynamics, but Watt as their creator is not mentioned. This paper presents some of Watt’s concepts of energy conversion, including his thermodynamic analysis of the Newcomen steam engine that marks the beginning of thermal engineering. The analysis illuminated the causes of the enormously high heat losses in the installation and showed the ways for their reduction. This led him to a new conception of the steam engine with a separate condenser. Not less important was Watt’s determination of some physical properties of water and steam used as the working substance. In the experiments he observed the decrease of the latent heat of steam with increasing temperature and its disappearance at very high temperature led him to postulate the existence of a thermodynamic critical state of water. He introduced the work associated with volume change into thermodynamics and illustrated it graphically. Several of Watt’s numerous ideas deserve to be included into the history of the thermodynamics of energy conversion but they are rarely mentioned in the scientific literature. Arguably the most important is the First Law of Thermodynamics, which he introduced in his 1769 patent and related works in 1774 and 1778.

摘要： Two bi-part combined models containing reaction equilibrium thermodynamic model and an equation of state(EoS)including cubic plus association(CPA)or modified Soave-Redlich-Kwong(SRK),were employed to correlate H_(2)S solubility in ionic liquids[emim][Lac],[bmim][Ac]and[emim][Pro].RETM and CPA/mSRK are responsible for chemical and phase equilibria calculations,respectively.The RETM defines a complex formation reaction between an H_(2)S and two IL molecules into the liquid phase so that a complex in the form of H_(2)S(IL)_(2)is probable to produce.On the other side,CPA/mSRK EoSs perform phase equilibria computations to find pressure and vapor phase concentrations.In the case of CPA,both of H_(2)S and the ionic liquids were considered as self-associating components which pursue 4 C and 2 B schemes,respectively.This model computes the pure IL parameters using experimental density data.In this work,critical properties were estimated through the modified Lydersen-Joback-Reid method,Eotvos and Guggenheim relations.Afterward,the binary systems were investigated by applying RETM.CPA presents average absolute deviations(AADs)equal to 2.41%,13.42%and 3.52%for[emim][Lac],[bmim][Ac],and[emim][Pro],respectively.Moreover,the AADs obtained by mSRK are 3.75%,5.07%,and 6.06%,respectively.As it is evident from the results,the combination of RETM with both CPA and m SRK EoSs will result in good correlation accuracy.

摘要： Effective distribution coefficients of 9 impurities in 1,2-diphenylethane have been calculated by directional crystallization under different ambient frozen temperature.The effect of varied zone size,temperature difference between the melt and ambient frozen environment,number of zone on purity of 1,2-diphenylethane have been also investigated during the process of zone refining.The results indicate that the product purity in the intermediate purified region with varied zone size is higher 0.04%–0.2%than that with constant zone size.The product purity increases with temperature difference between the melt and ambient frozen environment.The appropriate temperature difference is adopted 50°C.The product purity in the intermediate region of sample bar with 2 molten zones is higher 0.05%–0.43%than that with 1 molten zone.In addition,the change of enthalpy and entropy between impurities and 1,2-diphenylethane have been determined.

摘要： In this study,three kinds of amide functional group modified hyper-cross-linked adsorption resin were synthesized by alternating radical copolymerization in simple one-step and applied for 5-hydroxymethylfurfural(5-HMF)adsorption.The successful synthesis and properties of adsorbents were evaluated with Fourier transform infrared spectroscopy,scanning electron microscopy,nitrogen adsorption-desorption isotherms,thermogravimetric analysis,and elemental analysis.Poly(N,N’-4,4’-diphenyl methane-bismaleimide-alt-divinylbenzene)(poly(BDM-alt-DVB))resin exhibited highest adsorption capacity for 5-HMF(64.0 mg·g^(-1)wet resin)and excellent adsorption selectivity(a_(5-HMF/LA)=2.71±0.12,α_(5-HMF/FA)=13.88±0.15,α_(5-HMF/Glucose)=11.91±1.11)in the multi-component solution at 25°C.Langmuir isotherm model well fitted the equilibrium adsorption data within the initial 5-HMF concentration range of 0.5-10.0 g·L^(-1) with highest correlation coefficient.Furthermore,the thermodynamic parameters demonstrated that the adsorption of 5-HMF onto poly(BDM-alt-DVB)resin was spontaneous and exothermic.Kinetic study revealed that the adsorption process was fast,reaching equilibrium within12 min.Importantly,the poly(BDM-alt-DVB)resin also demonstrated excellent reusability.In summary,the poly(BDM-alt-DVB)resin will be useful in 5-HMF hydrolysate separation applications.

摘要： Normal titanium oxycarbide exhibits an excellent electrical conductivity and a high carrier concentration of approximately 10^(21) cm^(-3);however,the low Seebeck coefficient limits the thermoelectric application.In this study,first-principle calculations demonstrate that the metal vacancy of titanium oxycarbide weakens the density of state passing through the valence band at the Fermi level,impairing the carrier concentration and enhancing carrier mobility.Thermodynamic analysis justifies the formation of titanium oxycarbide with metal vacancy through solid-state reaction.Transmission electron microscopic images demonstrate the segregation of metal vacancy based on the observation of the defect-rich and single-crystal face-centered cubic regions.Metal vacancy triggers the formation of vacancy-rich and single-crystal face-centered cubic regions.The aggregation of metal vacancy leads to the formation of the vacancy-rich region and other regions with a semi-coherent interface,suppressing the carrier concentration from 1.71×10^(21) to 4.5×10^(20) cm^(-3) and resulting in the Seebeck coefficient from -11μV/K of TiC_(0.5)O_(0.5) to -64μV/K at 1073 K.Meanwhile,vacancies accelerate electron migration from 1.65 to 4.22 cm^(-2)·V^(-1)·s^(-1),maintaining high conductivity.The figure of merit(ZT)increases more than five orders of magnitude via the introduction of metal vacancy,with the maximum figure of 2.11×10^(-2) at 1073 K.These results indicate the potential thermoelectric application of metal-oxycarbide materials through vacancy engineering.

摘要： Currently,iron is extracted from ores such as hematite by carbothermic reduction.The extraction process includes several unit steps/processes that require large-scale equipment and significant financial investments.Additionally,the extraction process produces a substantial amount of harmful carbon dioxide(CO_(2)).Alternative to carbothermic reduction is the reduction by hydrogen plasma(HP).HP is mainly composed of exciting species that facilitate hematite reduction by providing thermodynamic and kinetic advantages,even at low temperatures.In addition to these advantages,hematite reduction by HP produces water,which is environmentally beneficial.This report reviews the theory and practice of hematite reduction by HP.Also,the present state of the art in solid-state and liquid-state hematite reduction by HP has been examined.The in-flight hematite reduction by HP has been identified as a potentially promising alternative to carbothermic reduction.However,the in-flight reduction is still plagued with problems such as excessively high temperatures in thermal HP and considerable vacuum costs in non-thermal HP.These problems can be overcome by using non-thermal atmospheric HP that deviates significantly from local thermodynamic equilibrium.

摘要： The first part of this paper is a condensed synthesis of the matter presented in several previous ones. It begins with an argumentation showing that the first and second laws of thermodynamics are incompatible with one another if they are not connected to relativity. The solution proposed consists of inserting the Einstein mass-energy relation into a general equation that associates both laws. The second part deals with some consequences of this new insight and its possible link with gravitation. Despite a slight modification of the usual reasoning, the suggested hypothesis leads to a simplification and extension of the thermodynamic theory and to the idea that relativity is omnipresent around us.

摘要： Cells are open systems that exchange energy and molecules with their environment.As any material system,they perform all the complex activities required for homeostasis and reproduction,obeying the thermodynamic laws.This viewpoint will argue that the basic logic governing the energy flux required to preserve cell organization and function is simple:to decrease the activation energy(Ea)of specific processes.Almost none of the possible chemical reactions and energy transformations inside a cell occur at a measurable speed at room or body temperature.Enzymes or other macromolecular structures speed up particular transformations by decreasing the corresponding energetic barriers.However,to maintain the systems in a homeostatic state,capable of sophisticated functions based on this simple strategy requires an inconceivably complex solution.The conclusion will point to the challenging and intricate problems that cells have solved to carve the highly regulated channel through which the energy flows,fueling the work of these nanoscale machines.

摘要： The thermodynamic approach to the evolution of human society shows that the energy generated by civilization disrupts the thermal balance of the Earth. This energy did not exist before the advent of civilization;it practically does not affect the thermal radiation of the planet and dissipates in the atmosphere in the form of heat, increasing the kinetic energy of gas molecules and, consequently, their temperature. Since air molecules cannot leave the Earth due to gravity, excess heat accumulates on the planet and contributes to global warming. A quantitative assessment of the effect is given. An analogy can be made: the energy generated by humanity heats the atmosphere, as a furnace heats a dwelling.

摘要： The studies on thermodynamics of irreversible processes currently concentrated on dissipation structure. While the most chemical reactions can't come to dissipation structure no matter how far the system from equilibrium. The chemical reaction rate ordinarily can't be described through a uniform equation at the same time. Here we describe the use of thermodynamics of irreversible processes theory to constitute the kinetic equation of homogeneous single chemical reacting system far from equilibrium. We find that when the equation is applied to the water-gas reaction, the equations of the fifth-order expression are obtained. Our results show that thermodynamics of irreversible process can be applied to chemical reacting systems which are far from equilibrium after the high-order term are considered.