![]() ![]() Tempergy itself is not a good measure of the internal energy per particle for an ideal gas of bosons below the critical temperature. ![]() Thus (E/N)/t is not constant, but rather is proportional to r 3/. (4.6) and (4.7), the energy per particle is A helpful result from statistical mechanics is that below the critical temperature, the internal energy per excited particle of an ideal Bose-Einstein gas is E/N ex = 0.77r. It turns out that the dimensionless entropies per particle of monatomic solids are typically A 3 with A 3 = (h 2 /(2тт'ткТ )) 3/ 2. which is consistent with о approaching zero for T (and t) -> 0. At T = 1 K, solid silver has о = 8.5 x 10“ ’. Similarly, one finds that diamond has a = 57.79. (6.13) implies the dimensionless entropy per particle, er = 50.68. What are typical values of o, the dimensionless entropy per molecule? Consider graphite, with molar entropy S mo = 5.7.1 K _1 mol -1 at standard temperature and pressure. Numericsĭimensionless entropy per molecule. Key Point 6.9 If temperature had been defined historically as an energy, entropy would have been dimensionless by definition and we might never have encountered the Kelvin temperature scale or Boltzmann’s constant. Tempergy is intensive, has energy units, and is not related to a stored system energy in general, as I discuss below. Internal energy is extensive and represents a stored energy. However they are very different entities physically. The kelvin can be viewed as an energy, i.e., 1 K=l.3807310223 J, and tempergy and internal energy have the same units. The universal gas constant R = 8.3145 J mol 1. Going one step further, define o, the dimensionless entropy per particle, The dimensionless entropy satisfies the property, I prefer to work with the number of molecules N rather than the number of moles. П = N/N a, and N a is Avogadro’s number, is tabulated. Instead, the entropy per mole, 5 moi = S/n, where The entropy 5 is proportional to the system’s number of particles N so it cannot be tabulated numerically in handbooks or databases. (3.3), S(E) = к In Cl(E), the system has internal energy E consistent with its temperature and pressure. Miller, Computational Methods of Neutron Transport, American Nuclear Society, 1993, ISBN: 2-4.In Eq. Hetrick, Dynamics of Nuclear Reactors, American Nuclear Society, 1993, ISBN: 3-2. Neuhold, Introductory Nuclear Reactor Dynamics, American Nuclear Society, 1985, ISBN: 9-4. Bezella, Introductory Nuclear Reactor Statics, American Nuclear Society, Revised edition (1989), 1989, ISBN: 3-2. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993. Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988. ![]() Physics of Nuclear Kinetics. Addison-Wesley Pub. Nuclear and Particle Physics. Clarendon Press 1 edition, 1991, ISBN: 978-0198520467 Nuclear Reactor Engineering: Reactor Systems Engineering, Springer 4th edition, 1994, ISBN: 978-0412985317 Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 8-1. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983). The fact that the absolute value of specific entropy is unknown is not a problem, however, because it is the change in specific entropy (∆s) and not the absolute value that is important in practical problems. For example, the specific entropy of water or steam is given using the reference that the specific entropy of water is zero at 0.01☌ and normal atmospheric pressure, where s = 0.00 kJ/kg. Normally, the entropy of a substance is given with respect to some reference value. ![]() In general, specific entropy is a property of a substance, like pressure, temperature, and volume, but it cannot be measured directly. Because entropy tells so much about the usefulness of an amount of heat transferred in performing work, the steam tables include values of specific entropy (s = S/m) as part of the information tabulated. M = mass (kg) T-s diagram of Rankine CycleĮntropy quantifies the energy of a substance that is no longer available to perform useful work. It equals to the total entropy (S) divided by the total mass (m). The specific entropy (s) of a substance is its entropy per unit mass. Engineers use the specific entropy in thermodynamic analysis more than the entropy itself. The entropy can be made into an intensive, or specific, variable by dividing by the mass. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |