Thermodynamic properties of steam and water pdf

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thermodynamic properties of steam and water pdf

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The following tables of the properties of steam are taken directly from Chapter 5. The reference state for all property values is the liquid at the triple point, for which state the specific internal energy and the specific entropy have been set to zero. Properties for coexisting phases: viscosity, thermal, conductivity, Prandtl number, dielectric constant, surface tension.

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Beginning in the International Association for the Properties of Water and Steam IAPWS recommended the use of a new model for calculation of the thermodynamic properties of water and steam.

The latter model had been used for 30 years for the calculation of thermodynamic properties of water for industrial, scientific, and academic applications. The new model is oriented toward facilitating calculations employing computers, improving accuracy, and improving consistency among the model's limiting regions as well as contributing towards improved process design and simulation.

This paper presents the IAPWS-IF97 model in summarized form, and results obtained in applying it to the thermodynamic properties of water, including enthalpy, entropy, internal energy, and volume, in the states of compressed liquid, liquid-vapor equilibrium, and superheated steam, using calculation algorithms developed using common, universally available computational techniques.

Keywords: thermodynamic properties, water and steam, calculation algorithms. This model was developed from a variety of experimental data available for H 2 O, which is the most abundant chemical compound in nature and also the most often used reagent in the chemical industry. Model IFC was tested and recognized as reliable for the calculation of the thermodynamic properties of water.

A great number of tables and diagrams existing in the literature, as well as computerized calculation programs were based on this model. The model was, however, was not easy to use. It required division of the area of validity of its equations into five different regions due to the complexity of the behavior of the thermodynamic properties of water.

Each region requires the use of different equations, and furthermore the basic thermodynamic model chosen in relation to the interdependence of properties is not the same for each region. Based on these considerations, beginning in the decade of the 's, the International Association for the Properties of Water and Steam IAPWS decided to promote the development of a new series of investigations directed towards obtaining a new formulation for a model for the calculation of thermodynamic properties of water and steam, which was officially adopted in termed the "IAPWS Industrial Formulation for the Thermodynamic Properties of Water and Steam", subsequently known as IAPWS-IF The new model was considered officially valid beginning in , but due to the need for modifying existing design procedures and computational program codes, the IAPWS recommended an introductory period lasting at least until the end of during which IAPWS-IF97 was not officially mandated.

The IAPWS-IF97 model consists of a group of equations for a group of five graphical regions representing thermodynamic properties of water, and valid in the following ranges:. Figure 1 shows the ranges within which the equations are valid, and the regions into which each range has been divided.

Although the number of regions in the new model coincides with number in the previous model, some differences exist in the form in which the IFC and IAPWS-IF97 models define the different regions.

Table 1 summarizes some of the constants and properties used in the model. Equation 1 covers the following ranges of pressure and temperature in Region 1 as shown in Fig. Where p s T represents the pressure at saturation, Region 4 in Fig. All the thermodynamic properties can be derived from equation 1 following the equations outlined in Tables 2 and 3. Table 2: Thermodynamic relations related to Gibbs free energy g and the corresponding adimensional equations.

Table 3: Derived from g used in equations of Table 1. The equation is expressed in adimensional form, and is separated into two parts, one for the ideal gas g 0 and the other residual g r , that is:.

Equation 2 covers the following ranges of pressure and temperature of Region 2 as shown Fig. All the thermodynamic properties for this region can be derived from equations 2, 3, and 4 following the equations outlined in Tables 1 and 2. In this case it must be considered that the equations of Table 2 must be applied both to the ideal part and to the residual part of the model. Thus, for example:. This equation can also be expressed in explicit form as the temperature as a function of the pressure in the following form:.

The basic equation for Region 3 differs from those of Regions 1 and 2 since it is an equation for the Helmholtz free energy f , which, expressed in adimensional form is:. The equation for Region 3 covers the following ranges of temperature and pressure as shown in Fig. All the thermodynamic properties can be derived from equation 7 according to the equations summarized in Tables 8 and 9. This equation is presented as one which is implicit for the saturation curve and its form allows it to be resolved indistinctly in an explicit form both for the saturation pressure p s as for the saturation temperature T s, which permits choosing the model most useful for calculation requirements.

The equation completely covers the range of the liquid-vapor saturation curve from the triple-point temperature to the critical point, as:. Region 5 is one of high temperature, and the basic equation for this region is based on the Gibbs free energy g in its adimensional form, and is separated into two parts, one for the ideal gas g 0 and the other the residual g r , similar to the model used in Region 2, as:.

Equation 2 covers the following ranges of pressure and temperature of Region 5 as shown in Figure 1. One reason for the choice of these three languages was because they have different options for the variables which can be handled, which can subsequently affect the accuracy of the results.

This is due, as can be seen from the tables containing the parameters of the model, that these parameters contain large numbers of significant figures. Another reason that justifies the choice of these languages is that at present they are extraordinarily common and easy to access. These programs are used to carry out calculations for different conditions of pressure and temperature and the different states of water. The values obtained for the different thermodynamic properties used in the model have been compared with values obtained from our bibliography.

These results are listed in Tables 14 , 15 , and Table Compressed liquid. In the columns, each upper value represents the result of calculations carried out using the model, and the lower value those obtained from our bibliography.

Table Liquid and saturated vapor. Table Superheated steam. This number of significant figures should not be mistaken for the significant figures of the properties calculated. Preston-Thomas, H. Setzman, U. Thermophysics, Vol 10, pp Wagner, W. For Gas Turbines and Power, Vol. Perry, R.

Servicios Personalizados Revista. This new model, termed IAPWS-IF97, was adopted beginning in , but an evaluation and changeover period was recommended before replacing the current model which had been developed in the 's IFC Keywords: thermodynamic properties, water and steam, calculation algorithms 1.

Table 8: Thermodynamic relations with the Helmholz free energy f and the corresponding adimensional equations. Table 9: Derivatives of f used in the equations of Table 8. Table 1: Constants and properties of water.

The model represents the thermodynamic properties of H 2 O with great accuracy. The model represents important advantages from the computational perspective: it is easy to calculate, does not present problems of iteration, and the calculations are executed quickly. The equations for the different regions continuously cover the ranges of variables, making interpolation unnecessary.

The different computer languages used are capable of adequately managing the accuracy required by the model; bit integers can be used for the integral variables, and double-precision 64 bit numbers for the floating point variables.

The fact that a simple and easily accessible language such as VBA is capable of adequately handling the model is especially relevant, as the calculations can be carried out from an electronic menu with VBA extensions. The model is capable of reproducing the tables for the properties of water over its entire range. Since the parameters of the model are the result of mathematical adjustments, all the significant figures of the parameters must be conserved in order to maintain the accuracy of the calculations.

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Beginning in the International Association for the Properties of Water and Steam IAPWS recommended the use of a new model for calculation of the thermodynamic properties of water and steam. The latter model had been used for 30 years for the calculation of thermodynamic properties of water for industrial, scientific, and academic applications. The new model is oriented toward facilitating calculations employing computers, improving accuracy, and improving consistency among the model's limiting regions as well as contributing towards improved process design and simulation. This paper presents the IAPWS-IF97 model in summarized form, and results obtained in applying it to the thermodynamic properties of water, including enthalpy, entropy, internal energy, and volume, in the states of compressed liquid, liquid-vapor equilibrium, and superheated steam, using calculation algorithms developed using common, universally available computational techniques. Keywords: thermodynamic properties, water and steam, calculation algorithms.

Boiler engineers used this tables to solve engineering problems and for the analysis of processes in a steam plant. Thermodynamic Properties of a fluid Download. Steam table. Steam Tables thermodynamics.

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Updated 01 Aug Provided thermodynamic properties are:. Temperature Pressure Enthalpy Specific volume Density Specific entropy Specific internal energy Specific isobaric heat capacity Specific isochoric heat capacity Speed of sound Viscosity Vapour fraction. All properties can be calculated with the inputs, p and T known, p and h known, h and s known and some with pressure and density known.

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Updated 01 Aug Provided thermodynamic properties are:. Temperature Pressure Enthalpy Specific volume Density Specific entropy Specific internal energy Specific isobaric heat capacity Specific isochoric heat capacity Speed of sound Viscosity Vapour fraction. All properties can be calculated with the inputs, p and T known, p and h known, h and s known and some with pressure and density known. X Steam are a full implementation of the IF formulation including all regions and all backward functions for good calculation speed.

System Simulation and Analysis. Plant Modeling for Control Design. High Performance Computing.


PDF | On Jan 1, , Sadiq Zarrouk and others published Thermodynamic and transport properties of Saturated Steam and Water | Find, read and cite all the.


COMMENT 4

  • The Second Law of Thermodynamics 6. Dafne G. - 10.05.2021 at 14:34
  • Critical Pressure: Kristen M. - 11.05.2021 at 23:12
  • At atmospheric pressure - 0 bar gauge or absolute Adelma M. - 14.05.2021 at 07:19
  • (Thermodynamic Properties of. Ordinary Water Substance). Based on the NIST Steam Tables. For ME Thermodynamics at IITBombay. Linda C. - 16.05.2021 at 11:34

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