Heats effusion

Those fixed-angle measurements reported to date have all used either a heated effusive inlet, or heated gas cell for sample admission [55, 56, 61, 62, 65]. Probably the higher sample number densities these sources generate, compared to a supersonic beam source, provides some compensation for the reduced collection efficiency in the fixed-angle measurement. 

Figure 2. Side-chain heat effusion (AH/j versus the number of side-chain carbon atoms (NJ. Key O, PDM-PMAS A, PMAS and , n-alkanes. The data for PMAS were obtained from reference 7.

The latent heat effusion is determined by rrultlplylrg the heat of fus or of water (334 k.7kg) oy the water content of the food. 

Heat effusion The heat required to melt a given quantity of a solid at its melting point... 

Compound Formula Melting point c Heat effusion ... 

Table 13.4 Melting Temperatures, Tm, heats effusion, AHp and crystallinity, Xc, from the first-heating DSC curves.

The heat effusion is 18.23 calories per gram. The heat of formation is 88.6 kilocalories per mole. Under constant pressure, the heat of combustion is 49.4 kilocalories per mole and at constant volume, the heat is 50.3 kilocalories per mole. At 25°C the latent heat of sublimation is 41.8 kilocalories per mole. 

Fig. 1 Changes in heat effusion and E-modulus of PHB due to the time of storing at room temperature.

Figure 24 Enthalpy of amorphous and crystalline PS. The difference between both equals the temperature-dependent heat effusion (crystallization). Equilibrium melting temperature and the corresponding heat of fusion are indicated by the vertical and horizontal thin lines, respectively. Data from ATHAS-DB. ...

Comparing this with equation (A.2.2), it is seen to predict exactly the same dependence of che effusion rate on pressure and temperature. Furthermore, Che ratio of specific heats y depends relatively weakly on che nature of the gas, through its molecularity, so che prediction chat dV/dt 1/M, which follows from equation (A-2.2) and agrees with Graham s results, is not markedly inconsistent with equation (A.2.3) either. 

Ergnss, m. effusion, discharge, overflow, -ge- stein, n. effusive rock, erh., abbTev. (erhitzt) heated. 

The vapor pressure of a molten metal can be measured with a device called a Knudsen cell. This is a container closed across the top by a thin foil pierced by a small, measured hole. The cell is heated in a vacuum, until the vapor above the melt streams from the small hole (it effuses). The weight of the material escaping per second tells the rate at which gaseous atoms leave. 

For comparison, Battles et al. (15) determined the partial heats of sublimation of Pu02(g) and Pu0(g) above PuOi.33 over the temperature range 1937 to 2342 K by means of mass spectrometric measurements with Iridium effusion cells. The absence of Iridium oxides or Iridium species In the vapor phase Indicated that Iridium was nonreducing toward plutonia. The partial heats of sublimation calculated from the slopes of the temperature dependency data yielded values of 127.1 1.2 and 138.8 1.6 kcal/mol for Pu0(g) and Pu02(g) ... 

Spectrometric measurements, mass, with irridium effusion cells, heats... 

I 72 Intensification of Heat Transfer in Chemical Reactors Heat Exchanger Reactors Table 12.5 Effusivity values according to the reactor material. 

There is also another key parameter linked to the choice of the material for the reactor. First, the choice is obviously determined by the reactive medium in terms of corrosion resistance. However, it also has an influence on the heat transfer abilities. In fact, the heat transport depends on the effusivity relative to the material, deflned by b = (XpCp) the effusivity b appears in the unsteady-state conduction equation. 

For high subcooling, the ratio of q"rn sub to the upper limit of boiling heat fluxes (an effusion limit to burnout) becomes... 

In the case of the demolition landfill mentioned above, pyrolysis supplied heat after the microorganisms reached their temperature limit. Eighteen months from the time of landfilling, obnoxious pyrolytic volatiles effused... 

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