Recovery factor enthalpy

When the compression process in the diffuser involves heat loss, the total enthalpy decreases from hoa to ho2- The enthalpy recovery factor, r, j, is defined as... 

Along the stagnation line of a swept cylinder, the recovery enthalpy is less than the stagnation enthalpy. Thus, the effect of surface mass transfer on the recovery factor, as shown in Fig. 6.25, should be considered in establishing the proper driving potential for the... 

Figure 4 shows the temperature dependence of the shift factors resulting from the reduction of the equilibrium creep data and the isothermal enthalpy recovery data shown in Figures 1, 2, and 3. The fit of equations 5 and 6 are also shown. Tj is taken as 207.5 C. The parameters used in the fits are, for equation 5 D/R = 1920 and T = 162 C and for equation 6 D/Ra =780, b/a = -1/560K and T2 = 151 C. Equation 6 seems to be better able to describe the temperature dependence in the glass due to the additional parameter. For modeling entMpy recovery, however, the results are expected to be identical with either equaticxi since the temperature range of interest is... 

One theory that describes the temperature dependence of relaxation time and structural recovery is the Tool-Narayanaswamy-Moynihan (TNM) model developed to describe the often nonlinear relationship between heating rate and Tg. In this model, the structural relaxation time, x, is referenced as a function of temperature (T), activation enthalpy (Ah ), universal gas constant (R), hctive temperature (7)), and nonlinearity factor (x) (Tool, 1946 Narayanaswamy, 1971 Moynihan et al., 1976) ... 

This fraction of the kinetic eneigy possessed by the mid-stage gas stream will be converted into additional enthalpy. There is no mechanism for reconverting this enthalpy into kinetic energy in an impulse blade, so there will be no recovery of any energy lost at the blade entry in an impulse stage. A reasonable estimate may be 1. The loss correction factor to be applied to the initial value of blade efficiency is simply (l-X ). The final calculation of blade efficiency for an operating impulse blade is thus... 

The reaction is reversible, and uranium hexafluoride is evolved on heating it is this factor that makes the addition compound useful for the recovery or purification of uranium hexafluoride. The dissociation pressure of the complex compound in the temperature range 80-320° is given by the equation log p = 10.88 — (5.09 X 103/ T), where p is the partial pressure of UF6 in millimeters of mercury, and T is the absolute temperature. A decomposition pressure of 1 atm is calculated to occur at 363°, and an enthalpy of formation of —23.2 kcal/mole of UF6 is deduced for the formation of the complex. The kinetics of the reaction between uranium hexafluoride and sodium fluoride have been studied by Massoth and Hensel (60, 61). The reaction appears to proceed initially at a rate determined by the surface area of the sodium fluoride, and then to become diffusion limited, The rate of the reaction is given by the expression k = 5.0 X 106 exp (—13,000// r) per hour the activation energy is thus 13,1 zk 0.2 kcal/mole of uranium hexafluoride. 

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