He3Pak Specifications…


Helium-3 (3He) is an stable isotope of helium that is increasingly being used in a number of areas such as fundamental physics, space technology, nuclear fusion and cryogenic engineering, especially in milli-Kelvin refrigeration technologies. The critical and normal boiling temperatures of 3He are 3.3157 K and 3.1968 K, respectively. 3He transitions to the superfluid phase below 0.0026 K. He3Pak was developed on the basis of:

  • saturation pressure equation valid from 2.6 mK to the critical point 3.3157 K,
  • saturation density equation valid from 2.6 mK to the critical point 3.3157 K,
  • melting pressure and density equations valid from 2.6 mK to 35 K, and
  • Debye fluid state equation using Helmholtz potential function valid for temperature from 2.6 mK to 1500 K, and pressure up to 20 MPa.

Equations for thermal conductivity and viscosity are valid for temperature from 2.6 mK to 500 K and pressure up to 20 MPa. The surface tension equation is valid from 3 mK to 3.3157 K.

All equations have been published in peer-reviewed journals. He3Pak covers the liquid-vapor equilibrium line, the liquid-solid equilibrium line and the compressed liquid, real gas and critical regions. The uncertainly for calculations of P-ρ-T, specific heat and sound velocity, and other properties are general within ±1%.

He3Pak was initially created by Dr. Yonghua HUANG and Professor Guobang CHEN as version 1.0 in 2005 in Zhejiang University, with technical help from Dr. Vincent Arp, Cryodata Inc. He3Pak was maintained by Dr. Yonghua HUANG after he graduated and moved to Shanghai Jiao Tong University. The version was updated to v1.2 in 2007 and to v2.0 in 2009. The code of v2.0 for the graphical user interface was completely re-written in Microsoft VB.Net and currently available in both 32bit and 64bit versions. The latest version improves many functions such as unit conversion, data output and print. It also provides more features like data plotting.

Calculated properties include:

  • P-rho-v-T
  • Enthalpy, Entropy, Gibbs Energy, Internal Energy, and Helmholtz Free Energy
  • Isochoric and Isobaric Specific Heats
  • Sound Velocity
  • Compressibility Factor
  • Adiabatic Compressibility
  • Joule-Thomson Coefficient
  • Volume Expansivity
  • Isentropic Expansion Coefficient
  • 2nd and 3rd Virial Coefficient
  • Grüneisen parameter
  • Latent Heat
  • dP/d(rho), dP/dT, d(rho)/dT, dB/dT
  • Thermal Conductivity
  • Viscosity
  • Surface Tension
  • …additional properties

For listing reference to the He3Pak program in publications, please use the following:

1. Huang Y. H., Chen G. B., Arp V. D. Debye equation of state for fluid helium-3. J. Chem. Phys., 2006, 125(5):054505.

2. Huang, Y.H., Chen, G.B., Arp, V.D., Helium-3 Thermophysical Properties Program – He3Pak, Version 2.0, Shanghai Jiao Tong University, 2009 (available from Horizon Technologies, Littleton, CO, USA, https://htess.com.)


He3Pak works via a user-friendly graphical front panel with on-line help documentation and PDF user’s manual. It provides both Metric and English unit systems. He3Pak is able to calculate thermophysical properties of 3He over a wide range of temperatures from 2.6 mK (the default lower limit value is set as 0.01 K) to 1,500 K and pressures up to 20 MPa.

He3Pak uses a standard installation package which installs:

  • Stand-alone executable.
  • Static library file (He3EOS.lib) created by Fortran compiler. This file contains all the functions/subroutines called by He3Pak (the user interface). He3EOS.dll can be incorporated into any Fortran code project, and should work for C/C++ with necessary procedure variable synchronization.
  • Standard Windows Dynamically Linked Library file (He3EOS.dll), which provides the interfaces to all functions/subroutines. This file can be used for Excel VBA programming or other language programming. The dll file has been tested in Excel x32 and x64 installations, and on Win32 and Win64 operating systems.

System requirements for the 32bit He3Pak 2.0 version:

  • Windows 10, Windows 8, and earlier Windows operating system
  • Microsoft .NET Framework 2.0
  • Intel Pentium 266MHz or above
  • 128 MB memory
  • At least 50MB free hard disk space
  • Keyboard and mouse
  • (He3Pak 2.0 has not been tested on the Windows 95 or Windows NT 4.0 systems.)

System requirements for the 64bit He3Pak 2.0.2 version:

  • Windows 8.1 or Windows 10 operating system
  • Microsoft .NET Framework 2.0
  • Intel Pentium 266MHz or above
  • 128 MB memory
  • At least 50MB free hard disk space
  • Keyboard and mouse