Helmholtz equation of state for n-pentene

YANG Jian1 MENG Xianyang1 GAO Kehui1 WU Jiangtao1

(1.Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi, China 710049)

【Abstract】To popularize the application of n-pentene in industry, such as chemical simulation, process optimization, and properties research, the equation of state for n-pentene was developed based on a body of experimental data that was critically assessed for internal consistency and for agreement with theory in this work. The Helmholtz energy as the fundamental property with independent variables of density and temperature was used for the equation of state. The equation of state is valid from the triple-point temperature to 500 K, with pressures up to 100 MPa and densities up to 15 mol⋅dm−3. Overall, the uncertainties in density range of the equation of state are 0.2% in the liquid region and 0.5% in the critical and vapor region. The uncertainty is 0.3% for the vapor pressure and 0.2% for the saturated liquid density. The uncertainties in the properties related to energy (such as heat capacity, sound speed, enthalpy and so on) are estimated to be 1%. The behavior of the equation of state is reasonable within the region of validity and at higher and lower temperatures and pressures.

【Keywords】 n-pentene; Helmholtz; equation of state; thermodynamics; thermodynamic properties;


【Funds】 National Natural Science Foundation of China (51676159) Natural Science Basic Research Programof Shaanxi Province of China (2015JM5214)

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This Article


CN: 11-1946/TQ

Vol 69, No. 04, Pages 1315-1323

April 2018


Article Outline


  • Introduction
  • 1 Experimental data
  • 2 Equation of state
  • 3 Discussion of equation
  • 4 Conclusion
  • Symbol description
  • References