Freon thermodynamic properties

Figure 5.32 Comparison of derived thermodynamic properties (water and Freon-12). (From May-inger, 1981. Copyright 1981 by Hemisphere Publishing Corp., New York. Reprinted with permission.)...

Here there is no obvious choice for the constant, as kinetic or potential energy. In making up tabulations of thermodynamic properties, we must arbitrarily select a value for this constant. For refrigerants such as Freon 12 (App. A.2) the constant is chosen so that m = —Pv for the saturated liquid at -40 F. This choice is made on the basis of convenience alone. Here v is the volume per pound-mass or specific volume. (After we introduce the enthalpy h, we will see that this choic is the same as choosing /i = 0 for saturated liquid at —40 F, This temperature is chosen because —40°F = — 40°C thus the common datum temperature for refrigerants is the same in countries using both temperature scales.) ... 

EQUATION OF STATE AND THERMODYNAMIC PROPERTIES OF FREON-21. //ENGLISH TRANSLATION OF TEPLOENERGETIKA 16/1/79-83,1969.//... 

Hamblin s abridged tables include the thermodynamic properties of water and steam, Freon-12, and air the enthalpies of some hydrocarbons and the critical constants of several inorganic and organic compounds are tabulated. 

TABLE 6. Experimental Study of the Thermodynamic Properties of Freon-20 at Low Pressure... 

For the calculation of thermodynamic properties of Freon-20 in the singlephase region at elevated pressures, Seshadri et al. [1.58] used an equation of the following type ... 

Thus, the system of generalized equations described above allows the calculation of thermodynamic properties of insufficiently studied substances in a wide region of state using a limited number of initial experimental data. However, the thermodynamic tables for Freon-20 in the single-phase region at elevated pressures are not presented in this handbook. This is so because of the absence of experimental data essential to verify the equations and the tables. 

The fundamental experimental and computational investigations of thermodynamic properties of Freon-21 (fluorodichloromethane) were carried out in the late 1960s. However, the results obtained are not fully reflected in the reference handbooks [0.8-0.10 and others]. Thus, the tables for the values of p, hy and s on the saturation line, which were published in paper [2.1], are presented in the reference survey [0.34] and the tables in the single-phase region in handbook [0.10]. The tables of thermodynamic properties on the saturation line (recommended in books [0.8-0.10]) repeat the data calculated by Rombusch and Giesen [0.46, 2.37], which are based on a small number of measurements [2.23-2.37]. 

In the present handbook significantly more complete information about the thermodynamic properties of liquid and gaseous Freon-21 is presented. 

TABLE 13. Experimental Studies of Thermodynamic Properties of Freon-21 in the Single-Phase Region... 

In reference books [0.7, 0.45, and others] the tables of thermodynamic properties of Freon-21 which were compiled by Benning and McHamess (1939) are recommended. 

It should be pointed out that in Refs. [2.17, 2.18, 2.21] the thermodynamic properties of saturated vapor of Freon-21 were calculated using the empirical vapor pressure curve equation... 

Thus, there are several equations of state which are suitable for the calculation of thermodynamic properties of gaseous Freon-21. For the compressed liquid, the equation of state and thermodynamic tables were compiled in Ref. [2.1] only. 

TABLE 22. Thermodynamic Properties of Freon-21 on the Saturation Line... 

The fundamental experimental investigations of the thermodynamic properties of Freon-22, which were carried out in 18 laboratories, are given in Tables 26... 

In the 1960s, in an Amsterdam laboratory under the supervision of A. Michels, pvT behavior of Freons-12, -13, and -22 was investigated in the interval T = 273-423 K at pressures up to 40 MPa. The study was carried out on a well-known experimental apparatus which allowed the use of the pressure-relieved variable-volume piezometer. The samples contained no less than 99.95% pure freon. The error in experimental data of pv values was usually evaluated to be 0.05%. The experimental results for Freons-12 and -13 obtained at this laboratory were published in 1966 and used to construct the tables of thermodynamic properties in Ref. [0.28]. However, the results of direct measurements for Freon-22 were not published and were known from the computational work of Martin [3.50]. 

The first tables of thermodynamic properties of Freon-22 were compiled by Graham and McHamess in 1945 based on the analysis of data by Benning and coworkers [2.23-2.26]. These tables were published practically unaltered in a number of handbooks [0.7, 0.45, 2.22, and others]. They include the values of V, hy and s on the saturation line at T = 170-325 K and in the region of superheated vapor at r 430 K and 1.8 MPa. 

Reference [3.1] shows that the equation of state obtained at MEI corresponds with the experimental data existing up to 1972 about thermodynamic properties of Freon-22 far better and in a wider region of state. From this equation, detailed tables of thermodynamic properties of liquid and gaseous Freon-22 were computed at T = 273-553 K and p = 0.1-35 MPa. These tables include the values of p, h, s, 0,/, Cp, c, w, 87, x, p, a, and 7 in the single phase and on the saturation line. 

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