Super-insulators

Most small Hquid helium containers are unpressurized heat leak slowly bods away the Hquid, and the vapor is vented to the atmosphere. To prevent plugging of the vent lines with solidified air, check valves of some sort are included in the vent system. Containers used for air transportation are equipped with automatic venting valves that maintain a constant absolute pressure with the helium container in order to prevent Hquid flash losses at the lower pressures of flight altitudes and to prevent the inhalation of air as the pressure increases during the aircraft s descent. Improved super insulation has removed the need for Hquid nitrogen shielding from almost all small containers. 

Figure 124. Transport box from Va-Q-tec. Due to the vacuum super insulation a cooling power of less than 10 W by a PCM is sufficient to sustain —20 °C for 4 days in the box in a +30 °C environment (picture Va-Q-tec GmbH)...

For road transport, liquid hydrogen (LH2) is transported in cylindrical super insulated cryogenic vessels in a semitrailer (see Fig. 12.5). The gross weight of a truck capable of carrying the LH2 container is typically about 401. The investment for a LH2 semitrailer amounts to about 500 000. The investment for a tractor capable to haul a semitrailer is about 160000. Table 12.3 displays the technical characteristics of hydrogen trailers. 

Super-Insulation -Level Probe Filling Line —s... 

Two notable methods to produce microcellular foams include gas supersaturation in combination with an extrusion process developed by MIT/Trexel [84-86] and the continuous extrusion process by Dow [87,88]. Super-insulating materials are made by the encapsulation of a filler material inside a barrier film, aluminum foil, or metallized film. These materials exhibit 5-7 times the R-value of typical nonvacuum insulating materials depending on vacuum level and barrier and filler type. Uses for these VIPs (vacuum insulation panels) include refrigeration and controlled-temperature shipping containers. 

When the transportation of natural gas in a pipeline Is not feasible for economic or other reasons, it is first liquefied at about 160°C, and then transported in specially insulated tanks placed in marine ships. Consider a 4-ni-diame(er spher ical tank that is filled with liquefied natural gas (LNG) at - 160 C. The lank is exposed to ambient air at 24°C with a heat transfer coefficient of 22 W/m °C. The tank is thin shelled and its temperature can be taken to be the same as the J.NG temperature. The tank is insulated with 5-cm-lhick super insulation that has an effective thermal conductivity of 0.00008 W/in °C. Taking the density and the specific heat of LNG to be 425 kg/m and 3.475 kJ/kg C, respectively, estimate how long it will take for the LN G temperature to rise to -ISO C. 

Super Insulated Houses - A type of house that has massive amounts of insulation, airtight construction, and controlled ventilation without sacrificing comfort, health, or aesthetics. 

The insulation selected was Linde SI-12 Super Insulation. This is a multilayer insulation consisting of aluminum foil separated by a web-type glass fiber with an optimum layer density of 13 layers/in. for lowest thermal conductivity. The reason for this choice was the resilience of the filler material, which permitted the final blanket to be folded and handled without damage to the structure. 

Recent Developments in Open Cell Polyurethane-Filled Vacuum Insulated Panels for Super Insulation Applications... 

P. Manini and E. Rizzi, Poster presented at the European Workshop on Vacuum Panel Technology for Super Insulation in Domestic Appliances and Industrial Applications, Milano, Italy, 1998. 

Multiple Layer (super-insulation with vacuum)... 

Schultz JM, Jensen KI, Kristiansen FH (2005) Super insulating aerogel glazing. Solar Mater Solar Cells 89 275-285... 

FIBERGLAS SUPER INSULATION IN COMPRESSED STATE FOR FIRST MINUTE... 

The outside layer is 14 cm of tungsten, which serves both to radiate absorbed x-ray and particle energies at 2000 K and to moderate the neutron spectrum. A layer of high temperature carbon insulation further softens the spectrum. Gamma rays generated in the outer layers are absorbed in a Pb Li layer which melts at 507 K and provides thermal capacity. Aluminized mylar super insulation follows, and a B C and W gamma absorber is added inside the superinsulation. The superconductor is NbTi stabilized with A1 in a Cu matrix. Construction of the superconductor and dewar is shown in Fig. 5. The coil carries 4.8 kA/cm at 8 T. The fractional volumes... 

Fig. 5 Schematic drawing of a liquid hydrogen tank system and its multilayer vacuum super insulation (MLVSI)...

The cryogenic part of the apparatus, designed for the production of a few standard cubic meters per hour, is housed in two containers with a volume of about 1 m. Due to the vacuum- ( 1 Pa) and the super-insulation, the heat flow into the equipment is small and the low temperatures can be obtained via the Joule Thomson effect. 

Liquid Hydrogen with a super insulated cryostat... 

---