Properties of Water and Steam as a Function

PROPERTIES OF WATER AND STEAM AS A FUNCTION OF TEMPERATURE AND PRESSURE... 

Properties of Water and Steam as a Function of Temperature and Pressure... 

Properties of Refrigerants, 6-133 to 135 Properties of Seawater, 14-15 to 16 Properties of Semiconductors, 12-78 to 90 Properties of Superconductors, 12-57 to 72 Properties of the Solar System, 14-2 to 3 Properties of Water and Steam as a Function of Temperature and Pressure, 6-14 to 15... 

The Ion-product of water Is represented as a function of temperature (0 to 1000 O and pressure (1 to 10,000 bars) by an equation with adjustable parameters which have been determined by least-squares procedures using data from the literature. The paper also contains the background for the international formulation for the Ion-product of water as Issued by the International Association for the Properties of Steam In May 1980. Also see [108]. 

Va.por Pressure. Vapor pressure is one of the most fundamental properties of steam. Eigure 1 shows the vapor pressure as a function of temperature for temperatures between the melting point of water and the critical point. This line is called the saturation line. Liquid at the saturation line is called saturated Hquid Hquid below the saturation line is called subcooled. Similarly, steam at the saturation line is saturated steam steam at higher temperature is superheated. Properties of the Hquid and vapor converge at the critical point, such that at temperatures above the critical point, there is only one fluid. Along the saturation line, the fraction of the fluid that is vapor is defined by its quaHty, which ranges from 0 to 100% steam. 

As a state property, the molar (or specific) volume can be determined once as a function of pressure and temperature, and tabulated for future use. Tabulations have been compiled for a large number of pure fluids. In very common use are the steam tables, which contain tabulations of the properties of water. Steam is a basic utility in chemical plants as a heat transfer fluid for cooling or heating, as well as for power generation (pressurized steam), and its properties are needed in many routine calculations. Thermodynamic tables for water are published by the American Society of Mechanical Engineers (ASME) and are available in various forms, printed and electronic. A copy is included in the appendix. We will use them not only because water is involved in many industrial processes but also as a demonstration of how to work with tabulated values in general. 

In order to meet the military performance specification, a foil laminate structure is currently used in the MRE food pouch. However, current research is investigating alternative multilayer polymeric packaging structures. [4, 5] Ethylene co-vinyl alcohol (EVOH) is one polymer that is being researched. EVOH is a crystalline, random copolymer of ethylene and vinyl alcohol. EVOH is known to be a superior barrier to oxygen however the barrier properties of EVOH diminish as the humidity increases. Also, the hydrophilic nature of the material becomes a problem with retort packaging applications because the process requires water and steam for sterilization. EVOH resins absorb moisture as a function of humidity and temperature, decreasing the barrier properties of the resin during the retort process. 

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