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Author(s): | V. Arp; Yonghua Huang; Ray Radebaugh; G.B. Chen; |
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Title: | THE DEBYE FLUID STATE EQUATION |

Published: | April 02, 2007 |

Abstract: | We describe a new form of a fluid state equation, based on a conceptual extrapolation from the Debye equation for the specific heat of solid materials. The Debye characteristic temperature, theta, which is nominally a constant for solids, becomes a function of the fluid density d. Further assuming theta = c1*d^(2/3)(1 + c2*d + c3*d^2 + ...) yields the conventional fluid virial equation in the high T and low d limit for a monatomic fluid. Additional terms must be added to describe (a) compressibility of the dense subcooled fluid, and (b) properties in the near-critical range. Discussion of the Gruneisen parameter and other factors is included. This Debye fluid theory has been useful in the state equation for 3He, continuous from 0.005 K to above room temperature. The mathematical form of conventional fluid state equations precludes their use below about 1/2 of the critical temperature, or 2 K for 3He, though they might be more accurate than the Debye equations above that temperature. |

Citation: | International Journal of Thermophysics |

Volume: | 28 |

Issue: | 2 |

Pages: | pp. 417 - 428 |

Keywords: | Debye theory; helium isotope; specific heat; state equation |

Research Areas: | Thermophysics |

PDF version: | Click here to retrieve PDF version of paper (7MB) |