Vapor pressure specific vaporization heat

General physical properties, including freezing point, normal boiling point, critical temperature, critical pressure, specific gravity, heat of formation, and heat of vaporization, of several common liquid propellants are listed in Table... 

Physical Properties. Physical properties of anhydrous hydrogen fluoride are summarized in Table 1. Figure 1 shows the vapor pressure and latent heat of vaporization. The specific gravity of the Hquid decreases almost linearly from 1.1 at —40°C to 0.84 at 80°C (4). The specific heat of anhydrous HF is shown in Figure 2 and the heat of solution in Figure 3. 

Temperature rc) Humidity kg HjO/kg dry air) Water vapor partial pressure (kPa) Water v K>r partial density (kg/m ) Water vaporization heat M/kg) Mixture enthalpy (kj/kg dry air) Dry air partial density (lKinematic viscosity (I0< mJ/s) Specific heat (kJ/K kg) Heat conductivity (W/m K) Diffusion factor water air (1 O mJ/s) Temperature rc)... 

Physical properties of the material (vapor pressure, specific heat, latent heat of vaporization, density, viscosity) ... 

Phase changes at constant temperature and pressure. Latent heats are changes in specific enthalpy associated with phase changes at constant 7 and P. For example, the latent heat of fusion (more commonly, the heat of fusion), A/fmlT, P),is the enthalpy change for the process in which a solid at temperature 7 and pressure P becomes a liquid at the same temperature and pressure, and the heat of vaporization, AH (T, P), is A for the process in which a liquid at T and P becomes a vapor at the same 7 and P. 

The specified variables are the final temperature and pressure, T2 and P2- The dependent variables are the vapor fraction, t /, the liquid and vapor compositions, X, and the total enthalpy of the two phases, /Z2 + H, and the heat duty, Q. The term isothermal should not be interpreted to imply that the transition from initial conditions to final conditions is at constant temperature is, in general, different from T. It simply means that within the flash drum the temperature, as well as the pressure, is fixed. The heat duty required to bring about the final conditions is equal to the enthalpy change, Q = (Hj + 2) - i> where is the enthalpy at and P,. Isothermal flash conditions may be represented by a point ( 2, P2) on tbs phase envelope diagram. It is clearly possible that this point may fall either within the phase envelope or outside it, in which case the system would be all vapor or all liquid (or dense phase). A flash drum operating at such conditions would have a single product and no phase separation would take place. In a single-phase situation, the dependent variables are the properties of the vapor or liquid product. The liquid or vapor composition is, of course, identical to the feed or overall composition, Z,. Note that any set of temperature and pressure specifications is feasible. 

HUMIDITY CHARTS FOR SYSTEMS OTHER THAN AIR-WATER. A humidity chart may be constructed for any system at any desired total pressure. The data required are the vapor pressure and latent heat of vaporization of the condensable component as a function of temperature, the specific heats of pure gas and vapor, and the molecular weights of both components. If a chart on a mole basis is desired, all equations can easily be modified to the use of molal units. If a chart at a pressure other than 1 atm is wanted, obvious modificatioi in the above equations may be made. Charts for several common systems besides air-water have been published. ... 

Melting point Vapor pressure at 25 °C Boiling point Heat of vaporization Heat of sublimation Specific gravity at 65 °C (liquid TXN)... 

As shown below, a hydrocarbon mixture is heated and expanded before entering a distillation column. Calculate the mole percentage vapor phase and vapor and liquid phase mole fractions at each of the three locations indicated by a pressure specification. 

With few exceptions, thermodynamic property tabulations are calculated from P-V-T meaz.urements and from zero-pressure specific heat values derived from spectroscopic measurements. It should be noted that the zero-pressure (ideal gas) specific heat values, Cp, for the cryogenic fluids are generally known with an uncertainty of less than 3 parts in 10,000 whereas the random deviations of the P-V-T data are of the order of 2 to 5 parts in 1000. The phase boundaries involve a further complication and, consequently, must be defined by additional experimental data. As a minimum requirement, measurements of the vapor pressure are sufficient for the calculation of thermodynamic property differences due to a phase change. This is indicated by the Clapeyron equation, which may be expressed... 

It will be assumed here that the equations for 2ero-pressure specific heat, vapor pressure, and the derivative of the vapor pressure with respect to temperature are all available. For example, the following forms have been found to be adequate for some fluids ... 

Thus, ATy jjjax and Apv,max representative for the same phenomena and can be indifferently used to calculate the maximum theoretical specific power l th,max-Nevertheless, the continuous exploitation of such a pressure difference is not trivial since the process evolves spontaneously to an equilibrium condition. Vapor formation causes the liquid phase to cool down, with a reduction in vapor pressure at the freshwater chamber. In the other chamber, vapor condenses with an increase of temperature and vapor pressure. If no heat is provided to the freshwater chamber and extracted from the saltwater chamber, the small pressure difference that drives the process rapidly vanishes, causing an interruption in the vapor flow. 

Other physical properties of fluid fertilizers that may have some specific importance are vapor pressure, specific heat, wettability, surface tension, refractive index, and conductivity. 

Significant amounts of condensables as load to the vacuum system can be an important consideration in the design and selection of the vacuum pump. Vacuum system suppliers must be provided condensable data in order to properly design the vacuum system. Information required include molecular weight, vapor pressure, specific heat, latent heat, transport properties, and solubility in water. 

Included is the density of water as a function of temperature, the vapor pressure, specific heat, partial molar volume, critical properties, and viscosity of water from 0 to 500 °C and to 8 kbar. Also see items [43] and [134]. 

These volumes contain extensive tabulations of physical data relevant to concentrated solutions of binary systems, both organic and inorganic. The properties that are tabulated include dielectric constant, viscosity,. equivalent conductivity, surface tension, diffusion and thermal diffusion coefficients, vapor pressure, specific heat, electrochemical data, enthalpy of combustion, enthalpy of dilution and solution, transition enthalpies, and other properties. These books contain extensive tabulations of data pertinent to water and electrolyte solutions. The data are well organized and there is a general compound index as well as references to the original data sources. 

Agent Chemical formula Halon no. Type of agent Approx. boiling point, opt Approx. freezing point, opt Specific gravity of liquid at 68 F (water = 1) Approx. critical temp., opt Estimated pressure, psig Latent heat of vaporization, cal/g water = 540 cal/g C02=138 cal/g... 

Physical and Chemical Properties - Information provided for each chemical includes the material s physical state, its molecular weight, boiling point, freezing point, critical properties (temperature and pressure), specific gravity, vapor (gas) density, the ratio of specific heats of vapor, and various... 

Flash Units. In simulators, the term flash refers to the module that performs a single-stage vapor-liquid equilibrium calculation. Material, energy, and phase equilibrium equations are solved for a variety of input parameter specifications. In order to specify completely the condition of the two output streams (liquid and vapor), two parameters must be input. Many combinations are possible—for exanple, temperature and pressure, temperature and heat load, or pressure and mole ratio of vapor to liquid in exit streams. Often, the flash module is a combination of two pieces of physical equipment, that is, a phase separator and a heat exchanger. These should appear as separate equipment on the PFD. Note that a flash unit can also be specified for batch operation, in which case the unit can serve as a surge or storage vessel. 

The mean specific molar heat capacity of the dry gas mix Cpm.ilT l, can be easily calculated or extracted as a stream property from a process simulator, for example, Aspen Plus [2]. The moisture exergy ei,H,tni,H20 must include the complete condensation of any water vapor. Although the specific enthalpy ho = 1890.3 kJ/ kmol and entropy So = 6.616 kJ/(lcmol K) of the reference water are fixed, the enthalpy hi in kj/kmol and entropy s, in kJ/(kmol-K) are computed applying the IAPWS-IF97 formulation for the gas temperature and partial H2O pressure. 

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