Thermodynamic Properties Of Carbon Dioxide Research Articles

Оценка степени влияния фактора подвижности стенок щели при расчёте величины протечек в рабочей части спирального компрессора. Часть 1

The scroll type compressor is widely used in the medium capacity segment of refrigeration and air conditioning technology including heat pumps. Today there is an active process of changing from hydrofluorocarbons to natural refrigerants with low global warming potential. CO2, with its low critical point and correspondingly high operating pressures, is gaining in importance. For operation with new refrigerants, the scroll compressor has to be adapted to take account of all its design features, the most important of which are the clearances in the machine's flow area. It has to be considered that the thermodynamic properties of carbon dioxide, different from hydrofluorocarbons, have a significant influence on the volume and energy values of the compressor. In this case relevance consists in increase of accuracy of compressor losses calculation and prediction of refrigeration machine characteristics. As the basic volumetric losses in the scroll compressor are leakages of working substance in its working part, and the process of flow of medium is unsteady, their quantitative component causes interest. The purpose of this work is to clarify the physical basis of the leakage process in the radial clearance and the degree of influence of various factors on it. Such analysis gives further opportunity to refine the methodology of calculation of leakages of compressed medium, taking into account the mobility factor of gap walls. It will raise accuracy of the received results which can serve as a base to prognosis of optimum characteristics of the compressor, due to their approximation and will allow to optimize designing of refrigerating machines at the chosen modes of work.

Two Crossover Soave–Redlich–Kwong Equations of State with Fully Analytical Crossover Functions for the Thermodynamic Properties of Carbon Dioxide

Two Crossover Soave–Redlich–Kwong Equations of State with Fully Analytical Crossover Functions for the Thermodynamic Properties of Carbon Dioxide

Calculating the Thermodynamic Properties of Carbon Dioxide in the Range of Pressures up to 200 MPa

A new fundamental low-parametric equation of state in the form of a reduced Helmholtz function is developed for carbon dioxide to describe the thermodynamic properties of normal substances. The equation of state makes it possible to describe the thermal and caloric properties of a gas, liquid, or supercritical fluid in the range of pressures up to 200 MPa with high accuracy that is close to experimental (except in the critical region). Carbon dioxide’s caloric properties and speed of sound in it are calculated without using any caloric data, except for the ideal gas enthalpy. The calculated values of the isochoric heat capacity, speed of sound, and other thermodynamic properties are in good agreement with experimental data (reliable reference tables).

Supercritical CO2: Properties and Technological Applications - A Review

The main goal of the present paper is to assess the available information so as to obtain a general procedure for dealing with the critical enhancement of the thermodynamic and transport properties of supercritical CO2 and CO2 containing binary mixtures for practical and scientific applications. The present review provides comprehensive analysis of the thermodynamic and transport properties of supercritical carbon dioxide and CO2 containing binary mixtures (experiment and theory) and their various technological and scientific applications in different natural and industrial processes. The available information for the thermodynamic and transport properties (experiment and theory) enhancement (anomaly) of supercritical carbon dioxide and SC CO2 + solute mixtures is comprehensively reviewed. The effect of long-range order parameter fluctuations on the thermodynamic and transport properties of supercritical fluids (SC CO2) will be discussed. Simplified scaling type equation based on mode-coupling theory of critical dynamics with two critical amplitudes and one cutoff wave number as fluid-specific parameters was used to accurately predict of the transport properties of supercritical carbon dioxide. The recommended values of the specific parameters (asymptotic critical amplitudes) of the carbon dioxide for practical (prediction of the thermodynamic and transport properties of the supercritical CO2 for technological applications) and scientific use were provided. The role of the critical line shapes of the carbon dioxide containing binary mixture (SC CO2+solvent) in determination of the critical behavior of the mixture near the critical point of pure supercritical solvent (CO2) is discussed. Krichevskii parameter concept for a description of thermodynamic behavior of dilute near-critical SC CO2+solute mixtures is also discussed. The structural and thermodynamic properties of the carbon dioxide containing binary mixtures near the critical point of pure solvent (CO2) are discussed.

The Joule-Thomson Effect for Refrigerants with Dopants of the Fullerenes and Carbon Nanotubes

The importance of thermodynamic and phase behavior of working fluids embedded with nanostructured materials is fundamental to new nanotechnology applications. The fullerenes (C60) and carbon nanotubes (CNT) adding to refrigerants change their thermodynamic properties the Joule – Thomson effect such as dislocation of critical point, gas – liquid equilibria shift at alias. Algorithm of refrigerant thermodynamic property calculations based on the NIST (National Institute of Standards and Technologies) equation of state at different carbon nanotube concentrations is proposed. Thermodynamic properties of carbon dioxide in the C60 and CNT presence are given. Considering the extremely large number of different both nanoparticle types and reference fluids, it is obvious that there is need for developing theoretically sound methods of the prompt estimation thermodynamic properties and phase equilibria for emerging working media. The effect of nanoparticles on the critical point shift for classical fluids doped by nanoparticles is examined. The regular and singular parts of thermodynamic surface of reference fluid and nanofluid (volume nanoparticle concentration < 5%) are suggested to coincide in the reduced form. The shift of critical point for nanoliquids of industrial interest is theoretically predicted. Results of calculations of phase equilibria for some nanofluids are described.

The engineering challenges of CO2 storage

The permanent underground storage of large quantities of anthropogenic carbon dioxide from thermal energy and industrial plant is widely recognised as a fundamental tool which can help to avoid the worst impacts of climate change. To achieve this effectiveness, it will require widespread global deployment in a new industry which would rival the current oil and gas industry in its scale and ambition. Many of the technologies for carbon dioxide storage are the adaptations of oil and gas technology, but there are some important differences. These arise from: 1. the thermodynamic properties of carbon dioxide, 2. the essential requirement for long-term storage site integrity, 3. the absence of an established and mature business model for the industry and 4. the contrasting regulatory environments between carbon capture and storage and oil and gas extraction. Whilst the underground injection of carbon dioxide can truly be considered a proven technology, there are a range of engineering challenges to achieve this in a safe and cost effective manner. This paper sets out to explore some of these challenges and concludes with a view of what next steps are required to progress carbon dioxide storage effectively within the UK. • The challenges of injecting carbon dioxide into offshore subsurface reservoirs: ^ Arrival processing (heating before injection) ^ Injectivity assessment – how many wells? ^ Platform or subsea? ^ Well design for long service operations and monitoring • The challenges of forecasting reservoir and injection performance within porous and permeable storage reservoirs: ^ Issues influencing carbon dioxide storage capacity ^ Assuring storage site containment integrity ^ Geology and engineering – uncertainty and risk • Where has the industry got to and what are the practical next steps?

Solubilities and Thermodynamic Properties of Carbon Dioxide in Some Biobased Solvents

Using the isochoric saturation method, solubilities of CO2 in five biobased solvents (BBSs) have been determined at temperatures between 293.15 and 323.15 K with 10 K intervals and pressure scope of (0–600.0) kPa. The BBSs were selected from glyceryl triacetate (GT), glycerol formal (GF), dl-1,2-isopropyli-deneglycerol (GAK), triethyl citrate (TEC), and acetyl triethyl citrate (ATEC). Henry’s constants and thermodynamic properties such as Gibbs free energy, enthalpy, and entropy of dissolution were derived from the solubility data. The gravimetric solubilities of CO2 in BBSs changed with the sequence of GT > ATEC > TEC ≈ GAK > GF. All the dissolution enthalpies were negative at each condition. The dissolution capacities of BBSs for CO2 were further compared with those of several common absorbents as well as ionic liquids. It was shown that they were similar to polyethylene glycol dimethyl ether (NHD) which is an industrial CO2 absorbent.

Optimization of a recompression supercritical carbon dioxide cycle for an innovative central receiver solar power plant

Peculiar thermodynamic properties of carbon dioxide (CO2) when it is held at or above its critical condition (stated as supercritical CO2 or sCO2) have attracted the attention of many researchers. Its excellent thermophysical properties at medium-to-moderate temperature range have made it to be considered as the alternative working fluid for next power plant generation. Among those applications, future nuclear reactors, solar concentrated thermal energy or waste energy recovery have been shown as the most promising ones. In this paper, a recompression sCO2 cycle for a solar central particles receiver application has been optimized, observing net cycle efficiency close to 50%. However, small changes on cycle parameters such as working temperatures, recuperators efficiencies or mass flow distribution between low and high temperature recuperators were found to drastically modify system overall efficiency. In order to mitigate these uncertainties, an optimization analysis based on recuperators effectiveness definition was performed observing that cycle efficiency could lie among 40%–50% for medium-to-moderate temperature range of the studied application (630 °C–680 °C). Due to the lack of maturity of current sCO2 technologies and no power production scale demonstrators, cycle boundary conditions based on the solar application and a detailed literature review were chosen.

Force field comparison and thermodynamic property calculation of supercritical CO2 and CH4 using molecular dynamics simulations

Thermodynamic properties of carbon dioxide and methane have been calculated under supercritical conditions up to 900K and 100MPa using isothermal-isobaric molecular dynamics simulations and the multistate Bennett acceptance ratio (MBAR) technique. Seven different carbon dioxide force fields (two single-site models, three rigid three-site models, and two fully flexible three-site models) were considered for preliminary density calculation. Those showing better accuracy when compared to experimental results were used to calculate the volume expansivity, isothermal compressibility, isobaric and isochoric heat capacities, Joule–Thomson coefficient, and speed of sound. The same properties were also calculated for methane using two different single-site models.The results show that force fields originally parameterized and optimized to reproduce vapor–liquid coexistence curves may be able to give accurate predictions of other thermodynamic properties in an extended temperature and pressure range. The results obtained with molecular simulations are generally more accurate than predictions with the Peng–Robinson equation of state, especially near critical conditions and at high pressures. Furthermore, the MBAR technique is successfully applied to improve the accuracy of results, decrease calculation uncertainties and reduce the number of simulations required to provide reliable property predictions over a range of temperatures and pressures. Recommendations are made as to which force fields are most accurate for the set of properties computed here.

High Efficiency and Low Cost of Electricity Generation from Fossil Fuels While Eliminating Atmospheric Emissions, Including Carbon Dioxide

NET Power has developed a novel, oxy-fuel thermodynamic power cycle [1] that uses hydrocarbon fuels, captures 100% of atmospheric emissions, including all carbon dioxide, and has a cost of electricity that is highly competitive with the best current systems that do not have CO2 capture. The proprietary system achieves these results through a closed-loop, high-pressure, low-pressure-ratio recuperated Brayton cycle that uses supercritical CO2 as the working fluid. The cycle exploits the special thermodynamic properties of carbon dioxide as a working fluid by eliminating the energy losses that steam-based cycles encounter due to the heat of vaporization and condensation. The compelling economics of the system are driven by high target efficiencies – 59% net LHV for natural gas and 51% net LHV for coal – and low projected capital and O&M costs, which are the result of utilizing only a single turbine, having a smaller plant footprint, and requiring fewer, smaller components than comparable fossil-fuel systems.NET Power, Toshiba Corporation, Exelon Corporation, and the Shaw Power Group are partnering to commercialize this system by developing a 50MWt facility that is scheduled to begin testing in 2014. This facility will generate electricity from natural gas and capture 100% of emissions, including all CO2. The initial design for a commercial system with an electrical output in the range of 200MWt to 500MWt is also under development. The turbine for the 50MWt plant is being designed at the 500MWt level and then scaled down for the demonstration plant to facilitate rapid development of the large-scale turbine in the future. The demonstration plant will test all components and control systems and the operability of the cycle, including 100% capture of carbon dioxide and other impurities, using a range of fuel gas compositions.The NET Power cycle will have an important impact on the power industry's ability to control and limit greenhouse gas emissions. Driven by its competitive cost when compared to state-of-the-art technologies without CO2 capture, the authors believe the NET Power cycle will remove economic barriers to the deployment of 100%-carbon-capture, fossil-fuel-based electricity generation technology. This will enable both the developed and developing world to produce cheap electricity that does not contribute to CO2-based climate change.

New Correlations for Predicting the Thermodynamic Properties of Supercritical Carbon Dioxide

Six new accurate and explicit correlations have been proposed in the present paper to predict the key thermodynamic properties of carbon dioxide under operational conditions anticipated for a typical carbon capture and sequestration (CCS) project – pressure = 1100 – 9000 psia (7 – 62 MPa) and temperature = 40 – 100 °C. These physical properties include entropy, enthalpy, internal energy, thermal conductivity, Joule-Thomson coefficient, and speed of sound, which all play an important role in controlling the PVT and thermodynamic behaviors of carbon dioxide associated with its flow through pipelines, wellbores, chokes, valves, and so on. The new correlations can predict carbon dioxide properties well matched to the high accuracy carbon dioxide property data available through the National Institute of Standards and Technology (NIST) web database [1].

Thermodynamic properties of carbon dioxide derived from the speed of sound

Thermodynamic properties of CO2 are derived from speed of sound in the temperature range 300 to 360 K (from 0 to 6 MPa), and 300 to 220 K (from 0 to 90% of the saturation pressure). The density, the specific heat capacity at constant pressure, and the specific heat capacity at constant volume are obtained by numerical integration of differential equations connecting the speed of sound with other thermodynamic properties. The set of differential equations is solved as the initial value problem, with the initial values specified along the isotherm at 300 K in terms of several accurate values of the density and the specific heat capacity at constant pressure. The density, the specific heat capacity at constant pressure and the specific heat capacity at constant volume are derived with the absolute average deviations of 0.018%, 0.19%, and 0.18%, respectively. The results of numerical integration are extrapolated to the saturation line for ρ, cp, and cv with the absolute average deviations of 0.056%, 2.31%, and 1.32%, respectively.

Atomistic computer simulations for thermodynamic properties of carbon dioxide at low temperatures : Kuznetsova, T. and Kvamme, B. Energy Conversion and Management, 2002, 43, (18), 2601–2623

Atomistic computer simulations for thermodynamic properties of carbon dioxide at low temperatures : Kuznetsova, T. and Kvamme, B. Energy Conversion and Management, 2002, 43, (18), 2601–2623

Atomistic computer simulations for thermodynamic properties of carbon dioxide at low temperatures

Investigation into the volumetric and energetic properties of two atomistic models mimicking carbon dioxide geometry and quadrupole moment covered the liquid–vapor coexistence curve. Thermodynamic integration over a polynomial path was used to calculate free energy. Computational results showed that the model using GROMOS Lennard–Jones parameters was unsuitable for bulk or interface CO 2 simulations. On the other hand, the model with potential fitted to reproduce only the correct density–pressure relationship in the supercritical region proved to yield the correct enthalpy of vaporization and free energy of liquid CO 2 in the low temperature region. NPT molecular dynamics was used to estimate the water–CO 2 interfacial tension and solubilities at 276 K for a liquid–liquid system at 100 and 300 atm.

Viabilty of atomistic potentials for thermodynamic properties of carbon dioxide at low temperatures

Investigation into volumetric and energetic properties of several atomistic models mimicking carbon dioxide geometry and quadrupole momentum covered the liquid-vapor coexistence curve. Thermodynamic integration over a polynomial and an exponential-polynomial path was used to calculate free energy. Computational results showed that model using GROMOS Lennard-Jones parameters was unsuitable for bulk CO(2) simulations. On the other hand, model with potential fitted to reproduce only correct density-pressure relationship in the supercritical region proved to yield correct enthalpy of vaporization and free energy of liquid CO(2) in the low-temperature region. Except for molar volume at the upper part of the vapor-liquid equilibrium line, the bulk properties of exp-6-1 parametrization of ab initio CO(2) potential were in a close agreement with the experimental results. Copyright 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1772-1781, 2001

A theoretical equation of state for real quadrupolar fluids

We have employed a theoretical equation of state for the calculation of the properties of real quadrupolar fluids whose interactions can be represented by a square-well with an embedded point quadrupole. This equation has only four disposable parameters: depth, range, diameter, and quadrupole moment. With this simple four-parameter equation we are able to predict the thermodynamic properties of carbon dioxide and nitrogen with good accuracy. This equation is able to reproduce the experimental (vapour + liquid) saturation curve and saturation pressures except near the critical region. Very good predictions of the speed of sound are obtained for both substances in the gaseous region. Molar isochoric heat capacities predictions for carbon dioxide in the liquid region are also presented.

A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple-Point Temperature to 1100 K at Pressures up to 800 MPa

This work reviews the available data on thermodynamic properties of carbon dioxide and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy. The function for the residual part of the Helmholtz free energy was fitted to selected data of the following properties: (a) thermal properties of the single-phase region (pρT) and (b) of the liquid-vapor saturation curve (ps, ρ′, ρ″) including the Maxwell criterion, (c) speed of sound w and (d) specific isobaric heat capacity cp of the single phase region and of the saturation curve, (e) specific isochoric heat capacity cv, (f) specific enthalpy h, (g) specific internal energy u, and (h) Joule–Thomson coefficient μ. By applying modern strategies for the optimization of the mathematical form of the equation of state and for the simultaneous nonlinear fit to the data of all these properties, the resulting formulation is able to represent even the most accurate data to within their experimental uncertainty. In the technically most important region up to pressures of 30 MPa and up to temperatures of 523 K, the estimated uncertainty of the equation ranges from ±0.03% to ±0.05% in the density, ±0.03% to ±1% in the speed of sound, and ±0.15% to ±1.5% in the isobaric heat capacity. Special interest has been focused on the description of the critical region and the extrapolation behavior of the formulation. Without a complex coupling to a scaled equation of state, the new formulation yields a reasonable description even of the caloric properties in the immediate vicinity of the critical point. At least for the basic properties such as pressure, fugacity, and enthalpy, the equation can be extrapolated up to the limits of the chemical stability of carbon dioxide. Independent equations for the vapor pressure and for the pressure on the sublimation and melting curve, for the saturated liquid and vapor densities, and for the isobaric ideal gas heat capacity are also included. Property tables calculated from the equation of state are given in the appendix.

A simulation/experimental study of the thermodynamic properties of carbon dioxide on graphite

Monte Carlo (MC) computer simulations are reported for a realistic model of carbon dioxide adsorbed on the exposed graphite basal plane. Isotherms were calculated using the grand canonical MC algorithm, and energies and densities were evaluated using the canonical MC algorithm. New experimental data for this system are also presented and, together with previous data, compared with the simulations. Excellent agreement is obtained. Auxiliary properties such as the coverage dependence of the average tilt angle (relative to the surface plane) for the molecules in the monolayer were evaluated. In addition, the temperature dependence of the monolayer capacity for this system is obtained directly from the simulations. The molecular areas in the completed monolayer that were obtained from these monolayer capacities are compared with other estimates including those obtained from a BET analysis of the isotherms. It is noted that the observed change in average tilt angle with increasing coverage produces a coverage-dependent molecular area that is not taken into account in the BET or any other known theory of multilayer adsorption.

Equations of state and thermodynamic properties of carbon dioxide and argon in the critical region

“Asymmetric” scale equations of state are obtained for carbon dioxide and argon in the critical region, on the basis of which thermodynamic properties are calculated. Comparison of calculated and experimental data shows that the error in thermodynamic property description lies within the limits of experimental uncertainty.

A scaled fundamental equation for the thermodynamic properties of carbon dioxide in the critical region

A scaled fundamental equation is presented for the thermodynamic properties of carbon dioxide in the critical region. The equation is constructed by combining earlier experimental pressure data of Michels and co-workers with new specific heat data obtained by one of the authors and represents the thermodynamic properties of carbon dioxide in the critical region at temperatures from 301.15 to 323 K and at densities from 290 to 595 kg/m3.