Pressure enthalpy, specific

Cp = specific heat e = specific internal energy h = enthalpy k =therm conductivity p = pressure, s = specific entropy t = temperature T = absolute temperature u = specific internal energy [L = viscosity V = specific volume f = subscript denoting saturated hquid g = subscript denoting saturated vapor... 

What is the potential temperature rise by undesired reactions or thermal decomposi- tion, such as from contaminants, impurities, etc. What are the consequences What is the maximum pressure Enthalpy of undesired reaction Specific heat Rate of undesired reaction as a function of temperature DTA/DSC Dewar flask experiments APTAC /ARC /RSST/VSP... 

Pressure Temperature Specific enthalpy Specific volume... 

Pressure Temperature °C Specific enthalpy Specific volume steam m lkg... 

The thermodynamic properties of a number of compounds are shown in Appendix D as pressure-enthalpy diagrams with lines of constant temperature, entropy, and specific volume. The vapor, liquid, and two-phase regions are clearly evident on these plots. The conditions under which each compound may exhibit ideal gas properties are identified by the region on the plot where the enthalpy is independent of pressure at a given temperature (i.e., the lower the pressure and the higher the temperature relative to the critical conditions, the more nearly the properties can be described by the ideal gas law). 

Because ASPEN is to be used with coal conversion processes, its streams can be designated to carry an arbitrary number of solids or solid phases. This is done by specifying any number of substreams. In fact, the conventional vapor/liquid stream is normally assumed as a substream and solids can comprise other substreams. For the conventional vapor/liquid substream, process data is carried on component molar flows, total molar flow, temperature pressure, specific enthalpy, specific entropy, density, molar vapor fraction, molar liquid fraction, and molecular weight. For solid substreams, which are called "non-conventional substreams," the characterizing data is not as deterministic. The information associated with these substreams is called "attributes". Such attributes may be particle size distribution, ultimate and proximate analyses, or other material specific information. Another type of substream is an "informa-... 

Here, is termed the specific chemical enthalpy, B, the specific thermal enthalpy and Bp the specific pressure enthalpy. The combination of the specificrthermal enthalpy, Bp, and the specific pressure enthalpy, Bp, may he named the specific physical enthalpy. When the material species is one of the components in a solution, Equations A-l through A-7 are valid, provided that the specific quantities are changed to the partial molar quantities. Note that superscript 0 refers to the standard state, and subscript 0 refers to the dead state cp is the specific heat, and v is the specific volume. 

Given in the literature are vapor pressure data for acetaldehyde and its aqueous solutions (1—3) vapor—liquid equilibria data for acetaldehyde—ethylene oxide [75-21-8] (1), acetaldehyde—methanol [67-56-1] (4), sulfur dioxide [7446-09-5]— acetaldehyde—water (5), acetaldehyde—water—methanol (6) the azeotropes of acetaldehyde—butane [106-97-8] and acetaldehyde—ethyl ether (7) solubility data for acetaldehyde—water—methane [74-82-8] (8), acetaldehyde—methane (9) densities and refractive indexes of acetaldehyde for temperatures 0—20°C (2) compressibility and viscosity at high pressure (10) thermodynamic data (11—13) pressure—enthalpy diagram for acetaldehyde (14) specific gravities of acetaldehyde—paraldehyde and acetaldehyde—acetaldol mixtures at 20/20°C vs composition (7) boiling point vs composition of acetaldehyde—water at 101.3 kPa (1 atm) and integral heat of solution of acetaldehyde in water at 11°C (7). 

What assumption did you make in solving question 2 regarding the effect of pressure on specific enthalpy ... 

Flow processes inevitably result from pressure gradients witliin tire fluid. Moreover, temperature, velocity, and even concentration gradients may exist witliin the flowing fluid. This contrasts witlr tire uniform conditions tlrat prevail at equilibrium in closed systems. The distribution of conditions in flow systems requires tlrat properties be attributed to point masses of fluid. Thus we assume tlrat intensive properties, such as density, specific enthalpy, specific entropy, etc., at a point are determined solely by the temperature, pressure, and composition at tire point, uirinfluenced by gradients tlrat may exist at tire point. Moreover, we assume that the fluid exlribits tire same set of intensive properties at the point as tlrough it existed at equilibrium at tire same temperature, pressure, and composition. The implication is tlrat an equation of state applies locally and instantaneously at any point in a fluid system, and tlrat one may invoke a concept of local state, independent of tire concept of equilibrium. Experience shows tlrat tlris leads for practical purposes to results in accord with observation. 

However, in high-pressure processes the second term on the right-hand side of Eq. (4.7) cannot necessarily be neglected, but must be evaluated from experimental data. Consult the references at the end of the chapter for details. One property of ideal gases that should be noted is that their enthalpies and internal energies are functions of temperature only and are not influenced by changes in pressure or specific volume. 

It is possible, as a general procedure, to form a new thermodynamic variable dependent solely on the thermodynamic state by combining any two or more of the thermodynamic variables above. An example of which we will make extensive use is specific enthalpy. Specific enthalpy, h (J/kg), is formed by amalgamating specific internal enetgy with two basic thermodynamic variables, pressure and specific volume ... 

Although the steam tables list steam properties against pressure and temperature, the fact that specific enthalpy and specific entropy are themselves thermodynamic variables means that it is possible to construe the steam tables as providing specific enthalpy as a tabular function of pressure and specific entropy. Alternatively, we may regard the tables as providing specific entropy as a tabular function of pressure and specific enthalpy. These two statements may be summarized mathematically by the two equations ... 

The equation set (16.41) requires the conversion from specific entropy at a given pressure to specific enthalpy at that pressure and vice versa. It turns out that we may derive a simple analytical expression for the rate of change of enthalpy with entropy. Then we may integrate from the base line of saturated steam conditions, along a line of constant pressure to find the appropriate value of specific enthalpy as a function of specific entropy. We are aided in these conversions by the fact that the enthalpy/entropy line for saturated steam is a fairly uncomplicated function, which may be approximated well by a low-order polynomial. 

Temperature T, F Vapor pressure p. Specific volume, fi /lb Enthalpy, Btu/Ib ... 

The stream report is an image of the material and energy flows in the plant and the basic document in flowsheeting. The format of results depends on the type of process and on the level of details. This should contain state variables, as temperature, and pressure, vaporised fraction, total and partial flow rates, molar fractions, composition, on molar and mass basis, enthalpy, specific volume, etc. Normally the information can be exported to a spreadsheet. 

This table summarizes the vapor pressure, enthalpy (heat) of vaporization, and surface tension of water as accepted by the International Association for the Properties of Water and Steam (www.iapws.org) for general and scientific use. The vapor pressure and heat of vaporization are calculated from the equation of state of Wagner and Pruss (Ref. 1). The temperature scale is lTS-90. Additional calculations at state points not listed below can be obtained by using the NIST Standard Reference Data program REFPROP (www.nist.gov/srd/nist23.htm) or the water-specific program Steam (www.nist.gov/srd/nistl0.htm). 

P = absolute pressure T — absolute temperature V = specific volume p = density = 1/F S = specific entropy H = specific enthalpy U = specific internal energy Cp — specific heat capacity at constarit pressure C = specific heat capacity at constant volume C(T = specific heat capacity at constant saturation W = velocity of sound fx = Joule-Thomson coefficient R = universal gas constant... 

The vapor ascending from a solution is only made up of solvent, if the vapor pressure of the solute is negligible. With consideration of the elevation of boiling point, the vapor is superheated, so that the enthalpy of evaporation is greater than the enthalpy of vaporization at system pressure. The specific enthalpy of evaporation q... 

Equation (2.28) establishes a relationship between pressure and specific volume (enthalpy is related via heat capacity and Eq. (2.29) with pressure and specific volume). It is called Hugoniot equation or Hugoniot shock adiabatic and consists of thermodynamic quantities only. 

This assumption is not justified in the presence of the dipole-dipole interaction and other more specifie interaetions. Therefore the theory of regular solutions poorly suits description of the behavior of solutions of polar substances. Inherent in this analysis is the assumption of molecular separation related to molecular diameters which neglects polar or specific interactions. The theory also neglects volume changes on dissolution. This leads to a disparity (sometimes very large) between internal energy of mixing used in the theory and the constant pressure enthalpy measured experimentally. 

Temper- ature cn Vapor Pressure (psia) Specific Volume Enthalpy btullbj Entropy (btuHb -°F) ... 

This book contains tables of the properties of water and steam from 0 to 800 and from 0 to 1000 bar which have been calculated using a set of equations accepted by the members of the Sixth International Conference on the Properties of Steam in 1967. Properties which are tabulated include the pressure, specific volume, density, specific enthalpy, specific heat of evaporation, specific entropy, specific isobaric heat capacity, dynamic viscosity, thermal conductivity, the Prandtl number, the ion-product of water, the dielectric constant, the isentropic exponent, the surface tension and Laplace coefficient. Also see items [43] and [70]. 

Point Temperature (°F) Pressure (psia) Specific Entropy (Mass) Btu/lbm/R Specific Enthalpy (Mass) Btu/lbm Reduced Pressure Exergy (Btu/lbm)... 

The enthalpy of subcooling is the amount by which the specific enthalpy of the coolant entering the channel is below the specific enthalpy of the saturated liquid at the system pressure. The specific enthalpy (enthalpy per unit mass) is defined by the relation... 

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