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To better understand the influence of aerosols on micro-properties of clouds and to facilitate weather modification experiments including the analysis of various materials' seeding effect on clouds and precipitation, Beijing Weather Modification Center has taken a decisive step forward by constructing an advanced facility known as Beijing aerosol and cloud interaction chamber (BACIC) in suburban Pinggu district. Boasting an impressive volume of 70 m3, BACIC is not only the largest of its kind in operation in China, but also a testament to the scale of the country's commitment to this sphere of atmospheric science. The enormity of the chamber's capacity facilitates the performance of a broad spectrum of investigations, thus enhancing the comprehensiveness and reliability of the results obtained.Inside BACIC, advanced instrumentation allows for the meticulous measurement and control of temperature, relative humidity, and background aerosol concentration. During 2019-2021, the chamber's capabilities extend further, as demonstrated by successful tests of its ability to create liquid and mixed-phase clouds. These attributes, combined with its capacity to control the cloud droplet size distribution as proved by comparative experiments involving changes in expansion rate and aerosol number concentration, solidify BACIC's standing as a prime location for warm cloud experimentation. The chamber has also been utilized to investigate effects of anthropogenic pollution over North China Plain (NCP) on cloud microphysics. Using ambient air and manipulating the expansion rate, a significant correlation is discovered between such pollution and the size distribution of cloud droplets. Interestingly, while an increase in aerosol leads to higher number of cloud droplets, it also causes a decrease in droplet size, typically within the range of 5-8 μm. Furthermore, an increase in aerosol number concentration leads to a decrease in the activation rate of aerosols into cloud droplets. This activation rate is around 10% for aerosol concentrations less than 5000 cm-3, and remains stable even when the aerosol concentration increases to 10000 cm-3.BACIC is also proved useful in conducting warm cloud expansion experiments involving different hygroscopic materials. It shows that the distribution of submicron (less than 1 μm) hygroscopic catalysts in a polluted environment leads to narrowing of the cloud droplet spectrum. It suggests that for the purpose of artificially reducing warm clouds or fog, it is recommended to use larger particle sizes. The results obtained from these diverse series of experiments have significantly contributed to theoretical knowledge and provide practical guidance for the ongoing development of artificial weather modification techniques.

The model of multiple particle production in [A. Ohsawa, Int. J. Mod. Phys. A (2023) 2350166.] assumes a fire-ball of a gas, consisting of grains, with the adiabatic and one-dimensional expansion, local equilibrium at the final state and the extended Maxwell distribution for the energy distribution of the grains. There are small and large p T (transverse momentum) processes for grains. The grain produces several hadrons to be observed in the experiments at the final state. The model describes well the pseudo-rapidity density distributions and the p T distributions at various incident energies. In this paper it is shown that the model reproduces well the incident energy dependences of 〈 p T 〉 (the average p T of produced particles), m c h (the charged multiplicity) and ρ 0 (the pseudo-rapidity density at η = 0). Furthermore it is shown that the inelasticity is almost energy-independent and K = 0. 5 in the energy region of s = 1 0 ∼ 1 0 4 GeV, and that the Feynman scaling law is violated. The model indicates that the fire-ball satisfies the conditions for quark-gluon plasma, that the grains of the large p T process may be identified with jets, and that p T 's of the grains in the large p T process are due to mutual collision of the grains during the one-dimensional expansion. [ABSTRACT FROM AUTHOR]

Organic Rankine cycles (ORC) are quite popular, but the overall efficiencies of these plants are rather very low. Numerous studies have been conducted in many scientific centers and research centers to improve the efficiency of such cycles. The research concerns both the modification of the cycle and the increase in the parameters of the medium at the inlet to the turbine. However, the efficiency of even these modified cycles rarely exceeds 20%. The plant modifications and the optimization of the working medium parameters, as a rule, lead to cycles with the high pressure and high temperature of live vapor and with a regenerator (heat exchanger) for the heating, vaporization and superheating of the medium. A new modified cycle with supercritical parameters of the working medium and with a new type of turbine has been described and calculated in the paper. For the first time, the isothermal turbine is proposed for supercritical organic cycles, though this solution is known as the Ericsson cycle for gas turbines. The innovative cycle and the usual ORC plants are characterized by almost identical block diagrams, while in the proposed cycle, the work of the turbine is obtained as a result of isothermal expansion and not in an adiabatic process. The analysis has been performed for 11 different working media and two cycles. The calculations have shown that power plants with isothermal expansion achieve better efficiency than cycles with adiabatic turbines. For example, the rise in efficiency changes from 8 percentage points for R245fa up to 10 percentage points for acetone. The calculations have proved that it is possible to obtain efficiency exceeding 50% for organic power plants. This is an outstanding result compared with modern steam and gas turbine units. [ABSTRACT FROM AUTHOR]

The spatial and temporal evolution of the absolute electron densities and temperatures in plasmas formed by nanosecond pulsed laser ablation of silicon in vacuum at two wavelengths (1064 and 532 nm), at similar irradiances, have been explored by complementary simulation (using combined hydrodynamic and adiabatic models) and experiment. Modelling the laser-target and laser-plume interactions with the POLLUX code reveals the evolving composition and dynamics of the laser induced plasma (LIP) during the incident laser pulse: 532 nm irradiation causes more ablation, but the LIP formed by 1064 nm excitation has a higher average charge state and expands faster. The experimental data, from the analysis of Stark broadened line shapes of SiIII and SiIV cations in time-gated, position- and wavelength-resolved images of the plume emission, allow characterisation of the plume dynamics at later times. These dynamics are compared with predictions from two forms of adiabatic expansion model. Both take as input parameters the plume properties returned by the POLLUX simulations for the end of the laser pulse, but differ according to whether the initial plasma is assumed isothermal or isentropic. The study illustrates the important λ-dependences of the target absorption coefficient (in establishing the ablated material density) and of electron–ion inverse bremsstrahlung absorption (in coupling laser radiation into the emergent plasma); the extents to which these interactions, the relative ablation yields, and the plume expansion dynamics depend on λ; and the importance of identifying appropriate initial conditions for adiabatic expansion modelling of LIP in vacuum. [ABSTRACT FROM AUTHOR]

For future use in modeling photoexcited dynamics and intersystem crossing, we calculate spin-adiabatic states and their analytical nuclear gradients within configuration interaction singles theory. These energies and forces should be immediately useful for surface hopping dynamics, which are natural within an adiabatic framework. The resulting code has been implemented within the Q-Chem software and preliminary results suggest that the additional cost of including spin-orbit coupling within the singles-singles block is not large. [ABSTRACT FROM AUTHOR]

We perform an electronic and nuclear flux analysis for nonadiabatic dynamics and its corresponding adiabatic counterpart, both of the wavefunctions of which are represented in the Born-Huang expansion. It is well known that the electronic-nuclear configurations (terms) in the expansion of the total wavefunction interfere each other through the nonadiabatic interactions and give birth to electronic and nuclear fluxes. Interestingly, even in the adiabatic dynamics without such nonadiabatic interactions, a wavefunction composed of more than one adiabatic state can undergo interference among the components and give the electronic and nuclear fluxes. That is, the individual pieces of the wavepacket components associated with the electronic wavefunctions in the adiabatic representation can propagate in time independently with no nonadiabatic interaction, and yet they can interfere among themselves to generate the specific types of electronic and nuclear fluxes. We refer to the dynamics of this class of total wavefunction as multiple-configuration adiabatic Born-Huang dynamics. A systematic way to distinguish the electronic and nuclear fluxes arising from nonadiabatic and the corresponding adiabatic dynamics is discussed, which leads to the deeper insight about the nonadiabatic dynamics and quantum interference in molecular processes. The so-called adiabatic flux will also be discussed. [ABSTRACT FROM AUTHOR]

We revisit the fundamental principles of thermodynamic equilibrium in relation to heat transfer processes within the Earth's atmosphere. A knowledge of equilibrium states at ambient temperatures (T) and pressures (p) and deviations for these p-T states due to various transport 'forces' and flux events give rise to gradients (dT/dz) and (dp/dz) of height z throughout the atmosphere. Fluctuations about these troposphere averages determine weather and climates. Concentric and time-span average values (z, Δt)) and its gradients known as the lapse rate = d < T(z) >/dz have hitherto been assumed in climate models to be determined by a closed, reversible, and adiabatic expansion process against the constant gravitational force of acceleration (g). Thermodynamics tells us nothing about the process mechanisms, but adiabatic-expansion hypothesis is deemed in climate computer models to be convection rather than conduction or radiation. This prevailing climate modelling hypothesis violates the 2nd law of thermodynamics. This idealized hypothetical process cannot be the causal explanation of the experimentally observed mean lapse rate (approx.−6.5 K/km) in the troposphere. Rather, the troposphere lapse rate is primarily determined by the radiation heat-transfer processes between black-body or IR emissivity and IR and sunlight absorption. When the effect of transducer gases (H2O and CO2) is added to the Earth's emission radiation balance in a 1D-2level primitive model, a linear lapse rate is obtained. This rigorous result for a perturbing cooling effect of transducer ('greenhouse') gases on an otherwise sunlight-transducer gas-free troposphere has profound implications. One corollary is the conclusion that increasing the concentration of an existing weak transducer, i.e., CO2, could only have a net cooling effect, if any, on the concentric average (z = 0) at sea level and lower troposphere (z < 1 km). A more plausible explanation of global warming is the enthalpy emission 'footprint' of all fuels, including nuclear. [ABSTRACT FROM AUTHOR]

Carnot's four-part ideal-gas cycle includes both isothermal and adiabatic expansions and compressions. Analyzing this cycle provides the fundamental basis for statistical thermodynamics. We explore the cycle here from a pedagogical view in order to promote understanding of the macroscopic thermodynamic entropy, the state function associated with thermal energy changes. From the alternative microscopic viewpoint the Hamiltonian H(q, p) is the energy and entropy is the (logarithm of the) phase-space volume O associated with a macroscopic state. We apply two novel forms of Hamiltonian mechanics to Carnot's Cycle: (1) Gauss' isokinetic mechanics for the isothermal segments and (2) Doll's Tensor mechanics for the isentropic adiabatic segments. We explore the equivalence of the microscopic and macroscopic views of Carnot's cycle for simple fluids here, beginning with the ideal Knudsen gas and extending the analysis to a prototypical simple fluid. [ABSTRACT FROM AUTHOR]

It is well known that large amounts of energy loss occurs at low temperature states in a wide range of industrial processes., The recovery and reuse of this energy is at the forefront of increasing the overall efficiencies of industrial systems. The aim of this paper is to investigate the effectiveness of using a Thermo-Fluidic Exchange (TFE) pump at low temperature conditions in both a Saturated-Vapour Organic Rankine Cycle (SORC) and a Trilateral Flash Cycle (TFC). For some low temperature applications, TFCs have been shown to achieve higher net power output than conventional SORCs, due to their ability to extract more heat from the source fluid. This is the subject of current research as a result of advancements made in the design of positive displacement machines for operation as twophase expanders. Conventional turbines cannot be used for TFCs as they must operate in the vapour phase. One drawback of the TFC is the higher working fluid mass flow rate required. Depending on the scale of the system, this can potentially cause difficulties with pump selection. A TFE pump uses heat input to the system to increase the pressure and temperature of the working fluid, rather than the work input in a standard mechanical pump. This paper compares the net power output achievable using both mechanical and TFE pumps with SORC and TFC systems. The results suggest that the TFE pump could be a viable option for TFC systems

In the spirit of the fewest switches surface hopping, the frozen Gaussian approximation with surface hopping (FGA-SH) method samples a path integral representation of the non-adiabatic dynamics in the semiclassical regime. An improved sampling scheme is developed in this work for FGA-SH based on birth and death branching processes. The algorithm is validated for the standard test examples of non-adiabatic dynamics. [ABSTRACT FROM AUTHOR]

Theory indicates that tropical cyclone intensity should respond to changes in the vertical temperature profile. While the sensitivity of tropical cyclone intensity to sea surface temperature is well understood, less is known about sensitivity to the temperature profile. In this paper, we combine historical data analysis and idealised modelling to explore the extent to which historical tropospheric warming and lower stratospheric cooling can explain observed trends in the tropical cyclone intensity distribution. Observations and modelling agree that historical global temperature profile changes coincide with higher lifetime maximum intensities. But observations suggest the response depends on the tropical cyclone intensity itself. Historical lower- and upper-tropospheric temperatures in hurricane environments have warmed significantly faster than the tropical mean. In addition, hurricane-strength storms have intensified at twice the rate of weaker storms per unit warming at the surface and at 300-hPa. Idealized simulations respond in the expected sense to various imposed changes in the temperature profile and agree with tropical cyclones operating as heat engines. Yet lower stratospheric temperature changes have little influence. Idealised modelling further shows an increasing altitude of the TC outflow but little change in outflow temperature. This enables increased efficiency for strong tropical cyclones despite the warming upper troposphere. Observed sensitivities are generally larger than modelled sensitivities, suggesting that observed tropical cyclone intensity change responds to a combination of the temperature profile change and other environmental factors. [ABSTRACT FROM AUTHOR]

We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of the third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well. [ABSTRACT FROM AUTHOR]

The total partition functions Q(T) and their first two moments QQ(T) and Q"(T), together with the isobaric heat capacities Cp(T), are computed a priori for three major MgH isotopologues on the temperature range of T = 100-3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro)vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to Q (T) at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q"(T) and Cp(T), principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of 24MgH, 25MgH, and 26MgH at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species. [ABSTRACT FROM AUTHOR]

The electron effective attenuation length (EAL) in free, neutral ethane clusters has been determined at 40 eV kinetic energy by combining carbon 1s x-ray photoelectron spectroscopy and theoretical lineshape modeling. More specifically, theory is employed to form model spectra on a grid in cluster size (N) and EAL (λ), allowing N and λ to be determined by optimizing the goodness-of-fit Χ²(N, λ) between model and observed spectra. Experimentally, the clusters were produced in an adiabatic-expansion setup using helium as the driving gas, spanning a range of 100-600 molecules in mean cluster size. The effective attenuation length was determined to be 8.4?±?1.9 Å, in good agreement with an independent estimate of 10 Å formed on the basis of molecular electron-scattering data and Monte Carlo simulations. The aggregation state of the clusters as well as the cluster temperature and its importance to the derived EAL value are discussed in some depth. [ABSTRACT FROM AUTHOR]

To optimize a vertical flash tank separator, the characteristics of the flow entering the separator are required to be known. A flash tank separator improves the performance of a refrigeration cycle by separating the liquid from liquid-gas flow and providing the evaporator with only liquid refrigerant. This technique improves the effective area and enhances the heat transfer coefficient in the evaporator. This paper investigates the influence of the inlet operating conditions to an expansion device, on the adiabatic two-phase flow development in a horizontal pipe downstream from the expansion device. This work also compares three dimensional numerical simulations and experimental observations for the two-phase flow development after the expansion device in the horizontal pipe. A general trend of the two-phase flow after the expansion device was gradually developed and the expansion length was identified at less than 200 mm from the inlet. The two-phase flow behaviour was recorded using a digital camera recording the flow behaviour at the upstream and downstream of the horizontal tube. The results revealed that an increase of the mass flow rate causes an increase in the void fraction and a reduction in the slip ratio in the developed region. The simulations underestimate the expansion length and the mean difference between the experimental data and the numerical results is 8 %. [ABSTRACT FROM AUTHOR]

Abstract—Experimental data are presented on the dynamics of quasi-adiabatic expansion of the foam formed from carbon-dioxide-plasticized polylactide in the course of fast depressurization. It is shown that, in the range of initial pressure, which corresponds to the region of transition between the subcritical and supercritical states of plasticizing agent, a substantial increase takes place in the resulting volume of the formed porous matrices. Study of the structure of synthesized matrices at the mesoscopic level provided using low-coherence reflectometry showed a dramatic difference from synthesis conditions far from the transition region. The observed features are interpreted in the framework of a qualitative model using an equation proposed by Ross to represent the foam state. The considered model takes into account the sign of increment of the internal energy of a plasticizing and foaming agent in the course of transition between the initial and final thermodynamics states of the foamed polymer. [ABSTRACT FROM AUTHOR]

Previous studies have indicated that flux transfer events (FTEs) grow as they convect away from the reconnection site along the magnetopause. This increase in FTE diameter may occur via adiabatic expansion in response to decreasing external pressure away from the subsolar region or due to a continuous supply of magnetic flux and plasma to the FTEs' outer layers by magnetic reconnection. Here we investigate an ensemble of 55 FTEs at the subsolar magnetopause using Magnetospheric Multiscale (MMS) multi‐point measurements. The FTEs are initially modeled as quasi‐force‐free flux ropes in order to infer their geometry and the spacecraft trajectory relative to their central axis. The MMS observations reveal a radially‐inward net force at the outer layers of FTEs which can accelerate plasmas and fields toward the FTE's core region. Inside the FTEs, near the central axis, plasma density is found to decrease as the axial net force increases. It is interpreted that the axial net force accelerates plasmas along the axis in the region of compressing field lines. Statistical analysis of the MMS observations of the 55 FTEs indicates that plasma pressure, Pth, decreases with increasing FTE diameter, λ, as Pth,obsv ∝ λ−0.24. Assuming that all 55 FTEs started out with similar diameters, this rate of plasma pressure decrease with increasing FTE diameter is at least an order of magnitude slower than the theoretical rate for adiabatic expansion (i.e., Pth,adiab. ∝ λ−3.3), suggesting the presence of efficient plasma heating mechanisms, such as magnetic reconnection, to facilitate FTE growth. Key Points: The forces inside FTEs observed by MMS suggest plasma acceleration toward and along the FTE's central axis causing plasma to escapeThe roles of adiabatic expansion and reconnection in FTE growth are explored using MMS observationsThe observed sub‐adiabatic decrease of plasma pressure as FTE size increases requires plasma heating mechanisms such as reconnection [ABSTRACT FROM AUTHOR]

Loss of coolant accidents (LOCA) are a serious type of accidents for nuclear reactors, when the integrity of the liquid-loop breaks. While in traditional pressurized water reactors, pressure drop can cause flash boiling, in Supercritical-Water Cooled reactors, the pressure drop can be terminated by processes with fast phase transition (flash boiling or steam collapse) causing pressure surge or the expansion can go smoothly to the dry steam region. Modelling the pressure drop of big and small LOCAs as isentropic and isenthalpic processes and replacing the existing reactor designs with a simplified supercritical loop, limiting temperatures for various outcomes will be given for 24.5 and 25 MPa initial pressure. Using the proposed method, similar accidents for chemical reactors and other equipment using supercritical fluids can be also analyzed, using only physical-chemical properties of the given supercritical fluid. [ABSTRACT FROM AUTHOR]

Abstract When serving as a lightweight structural member in many areas, the dynamic mechanical behavior of fiber-reinforced polymeric matrix composites, especially under different strain rates, means a lot to the optimization of structure design as to high-speed impact. Under different loading rates and directions, we experimentally and numerically investigated the strain rate effect on the impact compressive behavior of 3-D angle-interlock woven composites (3-D AWCs) composed of carbon fiber and epoxy resin. Based on the factual geometrical architecture of 3-D AWC, the meso-scale model, which considers the interfacial damage between the reinforcements and matrix, was established to visually characterize the deformation history and damage morphologies of 3-D AWCs during impact compression process. Further, we performed high strain rate compressive tests on the split Hopkinson pressure bar (SHPB) apparatus integrated with a high-speed photography system for capturing images of progressive damage process to validate the proposed mesoscopic model. The stress-strain curves of various strain rates show strain rate effect varies depending on loading direction. The rate sensitivity on the compressive failure strength exists at weft direction and through-thickness direction except for warp direction. Moreover, both from images and finite element model results, the localized adiabatic shear band induced by intense plastic strain, initiates mainly from epoxy resin matrix and propagates along the interface at all three loading directions. [ABSTRACT FROM AUTHOR]

There have been various varying speed of light (VSL) models with one free parameter, b , to characterize the time variation of the speed of light as a function of a scale factor, c = c 0 a b / 4 , based on the expanding universe. One needs to induce cosmological evolutions of other physical constants and quantities having different powers of scale factor as a function of b to satisfy all known local physics laws, including special relativity, thermodynamics, and electromagnetic force. These models should be based on the Friedmann–Lemaître–Robertson–Walker metric satisfying the isotropic and homogeneous three-space known as the cosmological principle. Adiabaticity is a necessary condition to keep homogeneity and isotropy because a net energy flux would falsify the isotropy if there is a preferential energy flow direction. It also might forge homogeneity if the outward (inward) flow is isotropic. Thus, any VSL model based on the expanding universe should preserve an adiabatic expansion condition to be a viable model. We show that this condition specifies the cosmological evolution of the Planck constant as ħ = ħ 0 a − b / 4 . • Cosmological time-varying speed of light model. • Adiabatic expansion of the Universe. • Cosmological evolution of the Planck constant. [ABSTRACT FROM AUTHOR]

The increase of the maximal cycle temperature is considered as one of the best tools to increase cycle efficiency for all thermodynamic cycles, including Organic Rankine Cycles (ORC). Technically, this can be done in various ways, but probably the best solution is the use of hybrid systems, i.e., using an added high-temperature heat source to the existing low-temperature heat source. Obviously, this kind of improvement has technical difficulties and added costs; therefore, the increase of efficiency by increasing the maximal temperature sometimes has technical and/or financial limits. In this paper, we would like to show that for an ideal, simple-layout ORC system, a thermodynamic efficiency-maximum can also exist. It means that for several working fluids, the thermodynamic efficiency vs. maximal cycle temperature function has a maximum, located in the sub-critical temperature range. A proof will be given by comparing ORC efficiencies with TFC (Trilateral Flash Cycle) efficiencies; for wet working fluids, further theoretical evidence can be given. The group of working fluids with this kind of maximum will be defined. Generalization for normal (steam) Rankine cycles and CO2 subcritical Rankine cycles will also be shown. Based on these results, one can conclude that the increase of the maximal cycle temperature is not always a useful tool for efficiency-increase; this result can be especially important for hybrid systems.

The efficiencies of the Organic Rankine Cycle (ORC) are not very high and only very seldom do they exceed 20%. The increase and optimization of initial parameters and certain modifications of the thermodynamic cycle make it possible to overcome these drawbacks. A new modified cycle has been described and analyzed in detail in the paper. Similarly to the Ericsson cycle for gas turbines, isothermal expansion in the turbine is suggested for the power plant with organic media. The new cycle and the typical ORC power plants have the same block diagram. The only difference is that expansion in the proposed cycle occurs not adiabatically but as an isothermal process. The thermodynamic calculations have been carried out for 11 various fluids and 4 different cycles. The obtained results have clearly shown that cycles with isothermal expansion (isothermal turbines) are characterized by remarkably higher efficiency than typical power plants with adiabatic turbines. The increase in efficiency varies from 6 to 12 percent points for cycles with saturated live vapor and from 4 to 7 percent points for cycles with superheated live vapor. The performed analyses have shown that it is possible to achieve a very high efficiency (over 45%) of organic cycle, which is a very competitive value. In such cases the proposed power plants can achieve an efficiency which is higher than that of modern steam turbine plants with supercritical parameters.

The shape of the temperature vs. specific entropy diagram of a working fluid is very important to understanding the behavior of fluid during the expansion phase of the organic Rankine cycle or similar processes. Traditional wet-dry-isentropic classifications of these materials are not sufficient; several materials remain unclassified or misclassified, while materials listed in the same class might show crucial differences. A novel classification, based on the characteristic points of the T−s diagrams was introduced recently, listing eight different classes. In this paper, we present a map of these classes for a model material, namely, the van der Waals fluid in reduced temperature (i.e., reduced molecular degree of freedom) space; the latter quantity is related to the molar isochoric specific heat. Although van der Waals fluid cannot be used to predict material properties quantitatively, the model gives a very good and proper qualitative description. Using this map, some peculiarities related to T−s diagrams of working fluids can be understood.

The objective of the present work was to determinate the map the spatial distribution of noise levels inside two commercial poultry housing having different adiabatic evaporative cooling systems, during the life cycle of birds. The noise level was assessed by a digital sound level meter. The data were measured manually at each point in six predetermined sections, totaling 36 points. Spatial distribution maps of noise were generated for the inside of each animal facility, using geostatistics technique through semivariogram analysis and interpolation by ordinary kriging. It concludes that the birds were, in general, subjected to noise levels above 62.0 dBA and during clean and disinfect (decontamination period) the sheds were at approximately 35.0 dBA. The spatial profile of the noise level to the productive environment provide for the attainment of more detailed information about the studied system. [ABSTRACT FROM AUTHOR]

Highlights • Cooler for the millikelvin range which is a closed system, gravity-independent, and continuous. • Thermodynamic analysis. • Estimation of the performance. Abstract In 1951 H. London proposed the adiabatic expansion of 3He in 4He to obtain cooling in the millikelvin range. In this paper the feasibility of the technique is investigated to provide a cooling power of 1 μW at 50 mK. Injecting 4He in a fixed amount of 3He is, in principle, a single-cycle method but it can produce continuous cooling by using two such expanders working in opposite phase. It is independent of gravity, so it may be a candidate for cooling in space. In contrast to the Planck mission it is a closed system which uses fixed amounts of 3He and 4He. [ABSTRACT FROM AUTHOR]

Compressed air energy storage technology is considered as a promising method to improve the reliability and efficiency of the electricity transmission and distribution, especially with high penetration of renewable energy. Being a vital component, the expander takes an important role in compressed air energy storage operation. The specific work of an expander can be improved through an isothermal expansion compared with the adiabatic expansion process due to a nearly constant temperature which enables the expander to operate with a high pressure ratio. In this study, a specific reciprocating expander with a high pressure ratio was developed and its adiabatic expansion characteristics were measured. Numerical modelling was performed to simulate adiabatic expansion. This model was also validated by experimental results. Based on these findings, we propose a quasi-isothermal expansion process using water injection into the expander cylinder. Modelling was also extended to simulate the quasi-isothermal process by introducing water–air direct heat transfer equations. Simulation results showed that when spraying tiny water droplets into the cylinder, the specific work generated was improved by 15.7% compared with that of the adiabatic expansion under the same air mass flowrate, whilst the temperature difference was only about 10% of that of the adiabatic process, and cylinder height was decreased by 8.7%. The influence of water/air mass flowrate ratio and the inlet temperature on the expander performance was also studied. [ABSTRACT FROM AUTHOR]

Most analytical and numerical flow modeling presuppose isothermal flow behavior in the reservoir. However, for high rates and large consequent drawdown gas reservoirs, the nonisothermal behavior becomes the norm due to the Joule-Thomson (J-T) effect. Other factors, such as a fluid's adiabatic expansion (AE), heat convection, and the heat exchange with surrounding formations may also make contributions. Accounting for this nonisothermal flow behavior becomes a necessity for accurately estimating a well's performance due to changes in fluid properties. This paper starts with the general energy balance in the reservoir and presents a semianalytical solution to estimate the nonisothermal, single-phase gas temperature in the reservoir during production. This solution considers the J-T effect, adiabatic expansion effect, transient temperature behavior, heat convection, and heat exchange of fluid with over and under-burden formation. The variations of gas viscosity, density, J-T coefficient as a function of temperature and pressure are taken into consideration by making a small spatial step at each computational node. A field case study validates the time-variant wellbore temperature profiles with the coupled reservoir heat-transfer model. Distributed temperature measurements or DTS during a drillstem test (DST) made this validation feasible. The J-T effect dominates in the near wellbore region due to dramatic pressure change. The J-T induced cooling usually occurs for gas in the reservoir. However, for high-pressure systems, the gas behaves like a liquid and gets heated up. For some intermediate pressure intervals, the gas temperature slightly increases with expansion, reach a plateau, and then gradually decreases as the gas moves toward the wellbore with declining pressure. By coupling the reservoir heat-transfer model with the wellbore heat-transfer model, one can monitor more accurately. [ABSTRACT FROM AUTHOR]

Protection of public health against pathogenic viruses transmitted through the airborne route requires effective sampling of airborne viruses for determination of their concentration and distribution. However, sampling viable airborne viruses is challenging as conventional bioaerosol sampling devices operate on inertia-based mechanisms that inherently have low sampling efficiency for virus aerosols in the ultrafine size range (< 100 nm). Herein, a Batch Adiabatic-expansion for Size Intensification by Condensation (BASIC) approach was developed for efficient sampling of virus aerosols. The BASIC utilizes adiabatic expansion in a supersaturated container to activate condensation of water vapor onto virus aerosol particles, thus amplifying the size of the particles by orders of magnitude. Using aerosolized MS2 bacteriophage, the BASIC's performance was evaluated and optimized both from the perspectives of physical size amplification as well as preservation of the viability of the MS2 bacteriophage. Experimental results show that one compression/expansion (C/E) cycle under a compression pressure of 103.5 kPa and water temperature of 25 °C was sufficient to increase the particle diameter from < 100 nm to > 1 µm; further increases in the number of C/E cycles neither increased particle number concentration nor diameter. An increase in compression pressure was associated with physical size amplification and a higher concentration of collected viable MS2. Water temperature of 40 °C was found to be the optimal for size amplification as well as viability preservation. No significant effect on particle size enlargement was observed by changing the dwell time after expansion. The results illustrate the BASIC's capability as a simple, quick and inexpensive tool for rapid sampling of viable airborne viruses. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present the influence of straight micro-fins on heat transfer coefficient and pressure drop. R410A flow boiling experiments were conducted in both smooth tube and the axial micro-finned tube. Data are taken at 10 °C saturation temperature for the vapor quality from 0.1 to 0.9, mass flux from 100 to 450 kg/s-m 2 , and heat flux from 10 to 20 kW/m 2 . The results in the smooth tube were compared with several correlations and used as a baseline. It was observed that straight micro-fin structure played an important role in the evaporative heat transfer. The heat transfer coefficient was significantly enhanced in the axial micro-finned tube, whose enhancement factor ranged from 1.03 to 1.48 with average of 1.34. As the mass flux and vapor quality was low, the straight micro-fins had stronger influence of the heat transfer coefficient since the liquid-phase refrigerant was easily trapped in the grooves of the axial micro-finned tube. The pressure drop penalty factor of the axial micro-finned tube ranged from 0.66 to 1.6, and the average was around 1.23. [ABSTRACT FROM AUTHOR]

The shape of the working fluid's temperature-entropy saturation boundary has a strong influence, not only on the process parameters and efficiency of the Organic Rankine Cycle, but also on the design (the layout) of the equipment. In this paper, working fluids are modelled by the Redlich-Kwong equation of state. It is demonstrated that a limiting isochoric heat capacity might exist between dry and wet fluids. With the Redlich-Kwong equation of state, this limit can be predicted with good accuracy for several fluids, including alkanes. [ABSTRACT FROM AUTHOR]

A novel method proposed to choose the optimal working fluid—solely from the point of view of expansion route—for a given heat source and heat sink (characterized by a maximum and minimum temperature). The basis of this method is the novel classification of working fluids using the sequences of their characteristic points on temperature-entropy space. The most suitable existing working fluid can be selected, where an ideal adiabatic (isentropic) expansion step between a given upper and lower temperature is possible in a way, that the initial and final states are both saturated vapour states and the ideal (isentropic) expansion line runs in the superheated (dry) vapour region all along the expansion. Problems related to the presence of droplets or superheated dry steam in the final expansion state can be avoided or minimized by using the working fluid chosen with this method. Results obtained with real materials are compared with those gained with model (van der Waals) fluids; based on the results obtained with model fluids, erroneous experimental data-sets can be pinpointed. Since most of the known working fluids have optimal expansion routes at low temperatures, presently the method is most suitable to choose working fluids for cryogenic cycles, applied for example for heat recovery during LNG-regasification. Some of the materials, however, can be applied in ranges located at relatively higher temperatures, therefore the method can also be applied in some limited manner for the utilization of other low temperature heat sources (like geothermal or waste heat) as well.

Aerogels of the tetrafluoroethylene radical polymerization products H(CF)R, where R is the radical formed by the abstraction of a hydrogen atom from a solvent molecule, have been obtained by replacing the solvent with supercritical CO and its subsequent rapid evaporation. According to the data of scanning electron and atomic force microscopy, the aerogel consists of loosely bound particles of 1-3 μm in diameter, which is two to three times that of colloid particles in the initial solution, where the particles consist of an oligomer framework filled with solvent molecules. The internal structure of the framework is manifested in the surface topography with a roughness coefficient of 1.6-1.8. High roughness leads to the formation of ultrahydrophobic coatings with contact angles of >160°. A model of supercritical drying in which the solvent is removed from the colloidal particles without alteration of the supramolecular structure is discussed. [ABSTRACT FROM AUTHOR]

We study brightness, volume and heights of the X-ray thermal emission components for an M-class solar flare on 17 May 2012. Based on the RHESSI data availability, we present the results for 01:42-01:58 UT over the late-flare phase. It is observed that the spatial evolution of the thermal emission components 6-12 and 12-18 keV are well associated with the hottest plasma in the corona. Results show that the ascending height ( ${\sim} 1.35 \times 10^{4}~\mbox{km}$ ) and speed ( ${\sim} 14.0~\mbox{km}\,\mbox{s}^{-1}$ ) of coronal source component 6-12 keV is slightly smaller than the ascending height ( ${\sim} 1.45 \times 10^{4}~\mbox{km}$ ) and speed ( ${\sim}15.1~\mbox{km}\,\mathrm{s}^{-1}$ ) of the coronal source component 12-18 keV. Mean flux intensity ( $I_{\mathit{mean}}$ ) of the 6-12 keV maintained a good fit ( $\chi^{2} = 0.41$ ) with the corresponding volume ( $V$ ) following strongly the power law [ $I_{\mathit{mean}} = (15.8\pm 0.21) V^{-1.28\pm 0.03}$ ]. In contrast, the 12-18 keV maintained a weak fit ( $\chi^{2} = 2.37$ ) following still the power law [ $I_{\mathit{mean}} = (0.19\pm 0.01)V^{-1.88\pm 0.16}$ ]. The power law indices ( $-1.28 \pm 0.03; -1.88\pm 0.16$ ) obtained by the observational analysis slightly differ from the power law index (−1.67) obtained by a theoretical model. The observations are consistent with adiabatic expansion of the coronal source component. [ABSTRACT FROM AUTHOR]

wave is considered. It is shown that the interaction qualitatively changes with the increase of electron energy, as the oscillations across the channel become relativistic. The "square-wave-like" profile of the transverse velocity in the relativistic case enables breaking of the adiabaticity that precludes electron energy retention in the non-relativistic case. For an electron with a relativistic factor γ0, the adiabaticity breaks if ωL/ωp0 ≪ √γ0. Under these conditions, the kinetic energy acquired by the electron is retained once the interaction with the laser field ceases. This mechanism notably enables electron heating in regimes that do not require a resonant interaction between the initially oscillating electron and the laser electric field. [ABSTRACT FROM AUTHOR]