General feature of supercritical fluid is discussed putting stress on its flow and heat transfer characteristics. In section 1 history of investigation and technological background are described briefly. Then the definition of supercritical fluid and descriptions on its thermodynamic and transport properties are made in section 2. The singularity and peculiarity of fluid near the critical point are discussed also. General nature of convective process, natural convection and forced convection of supercritical fluid are explained in section 3, 4 and 5 respectively.
The literature on the thermodynamic, electric and transport properties of helium 4 is reviewed. The thermodynamic properties are shown to be calculated using the equations taken from the NBS report. The data on the transport properties- viscosity and thermal conductivity-are assembled, and the NBS data are shown as the reliable values. The electrical properties are also discussed regarding dielectric constant, loss tangent and electrical breakdown.
Experiments relating to supercritical helium heat transfer are reviewed and discussed according to the following modes: 1) heat transfer under natural convection 2) heat transfer under forced convection Correlative expressions are used to compare with experimental data and to predict heat flux at various conditions in further design studies.
The work of the Cryogenic Division, NBS, on forced flow heat transfer to supercritical helium is introduced in some details, which is a part of the extensive study on helium heat transfer and its properties started in 1968.
A good cooling is essential to stabilize superconducting wires. Internally cooled superconducting wires or hollow superconductors have many advantages over conventional supercondutors which are cooled by immersion in liquid helium. The stability characteristics of hollw conductors are quite different from those of the conventional superconductors. This chapter is on the stability analyses of the hollow conductors. In section 2, the steady state stability is analyzed. In section 3, the propagation velocities of the normal regions are investigated. In section 4, the transient temperature distributions are calculated by solving numelically the thermal equilibrium equations of hollow condctors or superconducting cableh which are subjected to heat pulses.
A review on the development of magnets using superconducting hollow conductor at CERN is given. Some design problems in the large magnet such as Omega Project one are discussed regarding its electromagnetic feature and forced cooling system.