Tables Of Thermodynamic Properties Research Articles

Modelling Steam Power Cycle using Python

In this research article an attempt has been made to solve thermal power plant problems using Python programming. The hand calculations and use of thermodynamic property tables make it difficult sometimes to arrive at the correct solutions. But due to the PYroMAT library one can easily search for property data and solve for the Rankine cycle. Also, the python makes it so easy to plot the Rankine cycle once data at each equilibrium point is obtained. Two touch numerical problems have been used to show the capability of PYroMAT library in solving for the power plant thermodynamics problems. The results obtained from the codes matches exactly with the literature.

Mathematical Model to Elaborate the Table of Thermodynamic Properties

Purpose: The aim of this scientific contribution is to show the potential that integral calculus has offered to the analysis of thermodynamic processes. Method: Application of Integral Calculus. In this context, the document covers the theoretical principles of integral calculus, such as Theoretical framework and background, Geometric interpretation of the primitive, Primitive existence theorem. Results: Integral calculus and generalized thermodynamic models, and their applications in various thermodynamic analysis contacts such as the Generalized Enthalpy Model, the Generalized Entropy Model, and the Generalized Model applied to gas mixtures and the General Model to elaborate the properties table. Conclusion: The mathematical analysis developed in this document is very useful in engineering and applied physics environments, a fact that supports its common pedagogical practice in university institutions.

Preferential cavitation and friction-induced heating of multi-component Diesel fuel surrogates up to 450MPa

The present work investigates the formation and development of cavitation of a multicomponent Diesel fuel surrogate discharging from a high-pressure fuel injector operating in the range of injection pressures from 60MPa to 450MPa. The compressible form of the Navier-Stokes equations is numerically solved with a density-based solver employing the homogeneous mixture model for accounting the presence of liquid and vapour phases, while turbulence is resolved using a Large Eddy Simulation approximation. Simulations are performed on a tapered heavy-duty Diesel engine injector at a nominal fully-open needle valve lift of 350μm. To account for the effect of extreme fuel pressurisation, two approaches have been followed: (i) a barotropic evolution of density as function of pressure, where thermal effects are not considered and (ii) the inclusion of wall friction-induced and pressurisation thermal effects by solving the energy conservation equation. The PC-SAFT equation of state is utilised to derive thermodynamic property tables for an eight-component surrogate based on a grade no.2 Diesel emissions-certification fuel as function of pressure, temperature, and fuel vapour volume fraction. Moreover, the preferential cavitation of the fuel components within the injector's hole is predicted by Vapour-Liquid Equilibrium calculations; lighter fuel components are found to cavitate to a greater extent than heavier ones. Results indicate a significant increase of temperature with increasing pressures due to friction-induced heating, leading to a significant increase in the mean vapour pressure of the fuel and an increase of the mass of fuel cavitating, but at the same time to an unprecedented decrease of cavitation volume inside the fuel injector with increasing injection pressure. This has been attributed to the shift of the pressure drop from the feed to the back pressure inside the injection hole orifice as fuel discharges; as injection pressure increases, so does the pressure inside the orifice, confining the location of cavitation formation to a smaller volume attached to the upper part of orifice, thus restricting cavitation growth.

R22 ve alternatifleri R438A ile R417A soğutucu akışkanları için kızılötesi görüntü işleme teknikleri kullanarak, soğutma sistem performansının incelenmesi

Today, it has been observed that with various protocols, halogenic chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants will not be used in the future and various alternatives must be created. In the conventional cooling efficiency coefficient (COP) calculation method, thermodynamic property tables and pressure-enthalpy diagrams are used. Thanks to the proposed method, it will not be necessary to use these tables and diagrams when calculating the COP. It will be sufficient to take images from the regions indicated by the infrared imaging system. In this study, performance analysis of commercial refrigeration systems of R417A and R438A fluids that are alternative to R22 fluid, which are friendly to the ozone layer, has been performed. With the prohibition of the consumption of CFC gases, the use of HCFC gases, another gas group that damages the ozone layer, has been restricted and then banned. The most used of these gases is R22 gas. In order to perform the performances of reference R22 gas and R438A and R417A gases with infrared image analysis, two methods are proposed: COP with regional feature data acquisition and COP. In addition, on the two interfaces realized, the sizes obtained from infrared images are compared graphically and numerically. According to the obtained numerical and visual application results, R438A showed the closest performance to R22 gas. Compared to traditional computational performance tests, the ease of use of the system has shown that it is more advantageous in terms of remote measurement and simultaneous recording.

Design of refrigeration system using refrigerant R134a for macro compartment

The main objective of this study is to analyse and design an optimum cooling system for macro compartment. Current product of the refrigerator is not specified for single function and not compact in size. Hence, a refrigeration system using refrigerant R134a is aimed to provide instant cooling in a macro compartment with sizing about 150 × 150 × 250 mm. The macro compartment is purposely designed to fit a bottle or drink can, which is then cooled to a desired drinking temperature of about 8°C within a period of 1 minute. The study is not only concerned with analysing of heat load of the macro compartment containing drink can, but also focused on determining suitable heat exchanger volume for both evaporator and condenser, calculating compressor displacement value and computing suitable resistance value of the expansion valve. Method of optimization is used to obtain the best solution of the problem. Mollier diagram is necessary in the process of developing the refrigeration system. Selection of blower is made properly to allow air circulation and to increase the flow rate for higher heat transfer rate. Property data are taken precisely from thermodynamic property tables. As the main four components, namely condenser, compressor, evaporator and expansion valve are fully developed, the refrigeration system is complete.

ТЕРМОДИНАМІЧНІ ВЛАСТИВОСТІ ДЕВ’ЯТИ СУМІШЕЙ ГІДРОФТОРВУГЛЕВОДНІВ ТА ПРИРОДНИХ ХОЛОДОАГЕНТІВ

The equations of state of nine mixtures of hydrofluorocarbons and nature refrigerants were compiled on the basis of experimental p,ρ,T,x- and p,T,x-dataand for two mixturesalso on the basis of the data about isochoric heat capacity. The comparison of calculated values of density and isochoric heat capacity with the experimental ones were performed and the tables of thermodynamic properties were calculated.

Acoustic and Thermodynamic Properties of the Binary Liquid Mixture n-Octane + n-Dodecane

The velocity of sound in the binary liquid mixture n-octane + n-dodecane has been investigated by the method of direct measurement of the pulse-transmission time in the interval of temperatures 298–433 K and pressures 0.1–100.1 MPa. The maximum measurement error amounts to 0.1%. The density, isobaric expansion coefficient, isobaric and isochoric heat capacities, and isothermal compressibility of a mixture of three compositions have been determined in the intervals of temperatures 298–393 K and pressures 0.1–100 MPa from the data on the velocity of sound. Also, the excess molar volume, the excess isothermal compressibility, and the deviation of the velocity of sound from its value for an ideal liquid have been determined. The coefficients of the Tate equation have been computed in the above temperature interval. A table of thermodynamic properties of the mixture has been presented.

Equation of state and thermodynamic properties of saturated and superheated mercury vapors up to 1650 K and 125 MPa

Experimental data on the compressibility, sound velocity, and saturation pressures have been generalized for mercury vapor at densities <3 g/cm2 based on the equation of state with the second, third, and fourth virial coefficients. The virial coefficients have been calculated using the three-parameter Lennard-Jones potential m-6. The data have been generalized using the nonlinear weighted least-squares method. The parameters of the models and their enlarged error matrix taking into account random and systematic (in the first approximation) errors of the experimental data have been determined. Tables of thermodynamic properties of the saturated and superheated vapor have been calculated. The enthalpy drop error has been correctly calculated on the isentropic curve of the superheated vapor taking into account covariations of the equation of state parameters.

Acoustic and thermodynamic properties of the binary liquid system n-dodecane+n-hexadecane

By the method of direct measurement of the pulse-passage time, the velocity of sound in a binary liquid mixture n-dodecane+n-hexadecane has been investigated in the temperature range 298–433 K and in the pressure range 0.1–100.1 MPa. The maximum measurement error is 0.1%. Experimental data on the velocity of sound for the investigated mixture have been obtained for the first time. On the basis of the data on the velocity of sound, we have determined the density, the isobaric expansion coefficient, the isobaric and isochoric heat capacities, and the isothermal compressibility coefficient of a mixture of three compositions in the 298–433 K temperature range and in the 0.1–100.1 MPa range of pressures. The coefficients of the Tate equations in the above range of parameters have been calculated. A table of thermodynamic properties of the mixture is presented.

Engineering Model for Self-Pressurizing Saturated-N2O-Propellant Feed Systems

Self-pressurizing propellant feed systems, due to their overall simplicity, offer attractive options for propulsion system designers. These systems inherently exhibit transient properties as the tank-fluid mass bleeds down, and modeling the two-phase blow-down or evacuation process using first-principle physics is an extremely complex and time-intensive problem. As an alternative, a simple engineering model is developed for self-pressurized saturated-propellant feed systems. The model assumes an adiabatic expansion for which, during evacuation, the current tank-fluid entropy and the fluid entropy that has escaped through the feed system equate to the initial tank-fluid entropy. Mass flow through the outlet orifice is modeled as a two-phase nonhomogeneous nonequilibrium process. The evacuated entropy is subtracted from the total entropy at the state of the fluid leaving the tank, then the new state with the existing mass and entropy is calculated using two-phase thermodynamic property tables. In this manner, the tank-fluid state is calculated continuously during the evacuation. This propellant feed-system evacuation model is developed using saturation fluid properties for nitrous oxide, but it is readily extensible to other saturated propellants. Model results are compared with data derived from cold-flow tests conducted on a small-scale hybrid rocket motor. The comparisons show excellent agreement.

Thermodynamic property modeling for 2,3,3,3-tetrafluoropropene (HFO-1234yf)

This paper presents a timely and reliable equation of state for 2,3,3,3-tetrafluoropropene (HFO-1234yf) whose thermodynamic property information is strongly desired. The Patel–Teja (PT) equation of state and the extended corresponding state (ECS) model have been individually applied to property modeling for this new refrigerant. Comparisons of predicted values with the equation/model were made with the most recent experimental data. Both the PT equation of state and the ECS model can represent the vapor pressures with an accuracy of 0.2%. However, the ECS model is much better than the PT equation of state in the predictions for the liquid density and isobaric heat capacity. The uncertainties of calculated values with the ECS model are 0.5% in liquid density and 2.5% in isobaric heat capacity. The use of the ECS model is recommended for a detailed assessment of HFO-1234yf. Thermodynamic property tables and diagrams generated using the ECS model are provided.

A Reference Equation of State for the Thermodynamic Properties of Sulfur Hexafluoride (SF6) for Temperatures from the Melting Line to 625K and Pressures up to 150MPa

A new equation of state for the thermodynamic properties of the fluid phase of sulfur hexafluoride (SF6) in the form of a fundamental equation explicit in the Helmholtz energy is presented. The functional form consists of a part describing the ideal-gas state and the residual part as the difference between the real-fluid and the ideal-gas behavior. The residual part was developed using state-of-the-art linear and nonlinear optimization algorithms. It contains 36 coefficients, which were fitted to selected data for the thermal and caloric properties of sulfur hexafluoride in the single-phase region and on the vapor-liquid phase boundary. Especially for the thermal properties in the critical region, a very extensive and high-precision data set was available. In this work, information on the experimental data for the thermodynamic properties and all details of the new equation are presented. The new equation of state describes the pρT surface of sulfur hexafluoride with an uncertainty in density of less than 0.02%–0.03% from the melting line up to temperatures of 500K and pressures of 30MPa. In the critical region, including the immediate vicinity of the critical point, the uncertainty in pressure is less than 0.01%. Reliable data sets of other thermodynamic properties are reproduced within their experimental uncertainties. The primary data, to which the equation was fitted, cover the fluid region from the melting line to temperatures of 625K and pressures up to 150MPa. Beyond this range, the equation can be extrapolated with a physically reasonable behavior up to very high temperatures and pressures. In addition to the equation of state, independent equations for the vapor pressure, the saturated-liquid and saturated-vapor densities, the melting pressure, and the sublimation pressure are given. Tables of thermodynamic properties calculated from the new equation of state are listed in the Appendix.

Thermodynamic Properties of High-Temperature Jupiter-Atmosphere Components

A study on the thermodynamic properties of Jupiter-atmosphere chemical species important for the high-speed aerodynamics analysis of entry problems is reported. The included species are H 2 , H 2 4 , H 3 + , H + , H - , He, He + , He ++ , e - . Complete tables of thermodynamic properties of these species in the temperature range 50-50000 K have been obtained by using accurate sets of energy levels for both atomic and molecular species. The calculation method is described and relevant results are shown and discussed by comparison with previous data from other sources.

Reference Equations of State for the Thermodynamic Properties of Fluid Phase n-Butane and Isobutane

New formulations for the thermodynamic properties of fluid phase n-butane and isobutane in the form of fundamental equations explicit in the Helmholtz energy are presented. The functional form of the correlation equations for the residual parts was developed simultaneously for both substances considering data for the thermodynamic properties of ethane, propane, n-butane, and isobutane. Each contains 25 coefficients which were fitted to selected data for the thermal and caloric properties of the respective fluid both in the single-phase region and on the vapor–liquid phase boundary. This work provides information on the available experimental data for the thermodynamic properties of n- and isobutane, and presents all details of the new formulations. The new equations of state describe the pρT surfaces with uncertainties in density of 0.02% (coverage factor k=2 corresponding to a confidence level of about 95%) from the melting line up to temperatures of 340 K and pressures of 12 MPa. The available reliable data sets in other regions are represented within their experimental uncertainties. The primary data, to which the equation for n-butane was fitted, cover the fluid region from the melting line to temperatures of 575 K and pressures of 69 MPa. The equation for isobutane was fitted to primary data that cover the fluid region from the melting line to temperatures of 575 K and pressures of 35 MPa. Beyond the range described by experimental data, the equations yield reasonable extrapolation behavior up to very high temperatures and pressures. In addition to the equations of state, independent equations for the vapor pressures, the saturated-liquid and saturated-vapor densities, and the melting pressures are given. Tables of thermodynamic properties calculated from the new formulations are listed in Appendix 2. Additionally, a preliminary equation of state for propane is presented that was developed in the course of the simultaneous optimization. This equation has the same functional form as the equations of state for n- and isobutane.

Thermodynamic Model of Hydrazine that Accounts for Liquid-Vapor Phase Change

The work carried out to develop a thermodynamic model of hydrazine with the theoretically built-in capability to account for liquid-vapor phase transitions and suited for implementation in two-phase flow solvers is described. After introductory considerations of fluid dynamics aspects and thermodynamic stability, the method of constructing the model based on an assumed state equation p=p(T, v) and of perfect-gas, constant-pressure, specific-heat data available from tables of thermodynamic properties published in the literature is described. The corresponding fundamental relation is given in terms of the Helmholtz potential. Subsequently, the liquid-vapor phase equilibrium is considered and resolved via equations in line with the standard thermodynamic principles of energy minimization or entropy maximization. Aspects of model validation are discussed with respect to the liquid-vapor saturation curve, vaporization enthalpy, density, and constant-pressure specific heat of the liquid phase. A description of other theoretical models published in the literature, together with a comparative analysis of their features relevant to the context of this work, is also included.

A technique for preparing thermodynamic property tables using incomplete data sets

Extended corresponding states (ECS) algorithms provide versatile predictions for the thermophysical properties of mixtures. The NIST14 computer database implements an ECS model and the resultant property calculations are remarkably accurate for a wide variety of mixtures. This model emphasizes single phase calculations for many systems and properties, and it has the usual difficulties with the phase envelope and the critical region. Thermodynamic property tables are calculated most accurately when data are available throughout the ranges of the tables. Unfortunately, data are often not available over the entire ranges or in particularly important regions. We have observed that the deviations of the NIST14 model from PVT data for several mixtures have the same basic shape for each mixture. A single, interpolative function can adjust the model to fit compression factors for several systems within ±0.1%. Utilizing this function along with NIST14 forms a technique employing available experimental data to calculate accurately (1.0–3.5%) energies, enthalpies and entropies even in regions which lack experimental data or are near the critical point. This is not a correction for NIST14, but a method using NIST14 along with data to create accurate property tables in regions which lack data or which present difficulties for models.

Thermodynamic Properties of Alkali Metal Hydroxides. Part 1. Lithium and Sodium Hydroxides

The data on thermodynamic and molecular properties of the lithium and sodium hydroxides have been collected, critically reviewed, analyzed, and evaluated. Tables of thermodynamic properties (C°p,Φ°=−(G°−H°(0)/T, S°, H°−H°(0), ΔfH°, ΔfG°) of these hydroxides in the condensed and gaseous states have been calculated using the results of the analysis and some estimated values. The recommendations are compared with earlier evaluations given in the JANAF Thermochemical Tables and Thermodynamic Properties of Individual Substances. The properties considered are: the temperature and enthalpy of phase transitions and fusion, heat capacities, spectroscopic data, structures, bond energies, and enthalpies of formation at 298.15 K. The thermodynamic functions in solid, liquid, and gaseous states are calculated from T=0 to 2000 K for substances in condensed phase and up to 6000 K for gases.

Equation of state and thermodynamic properties of 1,1,1,2-tetrafluoroethane (refrigerant R134a)

An equation of state and tables of thermodynamic properties of R134a in the saturation state and in the one-phase region are obtained in the temperature interval 320–500 K at pressures ranging from 0.01 to 7.5 MPa.

Speed of sound in liquid R134a

The speed of sound for liquid R134a (1,1,1,2-tetrafluoroethane) has been measured along isotherms at temperatures from close to the triplee point to above the critical temperature (180–380 K) at pressures from near saturation to 70 MPa. The measurements were made by using a pulse-echo-overlap technique at 3 MHz. A rational approximant fits the data with a standard deviation of 0.45 m s −1. Because the speed of sound depends on the molar volume and the adiabatic compressibility, these data may be used with density and heat capacity data to construct accurate thermodynamic property tables.

A New Equation of State and Tables of Thermodynamic Properties for Methane Covering the Range from the Melting Line to 625 K at Pressures up to 1000 MPa

This work reviews the data on thermodynamic properties of methane which were available up to the middle of 1991 and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy. A new strategy for optimizing the structure of empirical thermodynamic correlation equations was used to determine the functional form of the equation. The Helmholtz function containing 40 fitted coefficients was fitted to selected experimental data of the following properties: (a) thermal properties of the single phase (pρT) and (b) of the liquid-vapor saturation curve (psρ′ρ″) including the Maxwell criterion, (c) speed of sound w, (d) isochoric heat capacity cv, (e) isobaric heat capacity cp, (f) difference of enthalpy Δh, and (g) second virial coefficient B. Independent equations are also included for the vapor pressure, the saturated liquid and vapor densities, the isobaric ideal gas heat capacity and the melting pressure as functions of temperature. Tables for the thermodynamic properties of methane from 90 K to 620 K for pressures up to 1000 MPa are presented. For the density, uncertainties of ±0.03% for pressures below 12 MPa and temperatures below 350 K and ±0.03% to ±0.15% for higher pressures and temperatures are estimated. For the speed of sound, the uncertainty ranges from ±0.03% to ±0.3% depending on temperature and pressure. Heat capacities may be generally calculated within an uncertainty of ±1%. To verify the accuracy of the new formulation, the calculated property values are compared with selected experimental results and existing equations of state for methane. The new equation of state corresponds to the new International Temperature Scale of 1990 (ITS-90) and is extrapolable up to pressures of 20000 MPa.