TurboHeTra – Zweiflutiges kryogenenes Transfersystem mit Pumpe zur verlustreduzierten Flüssigheliumversorgung

• Applicant: Professor Dr. Christoph Haberstroh
• Subject Area: Energy Process Engineering ; Hydraulic and Turbo Engines and Piston Engines
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566285956

Liquid helium (LHe) is indispensable for cooling at 4 K, close to Absolute Zero, as required for basic research, material development and almost all today's superconductivity applications. Corresponding, self-operated helium liquefiers are therefore standard at almost all universities and institutes in this field. Such helium plants are cost-intensive (typically 2 M€ per plant), helium reliquefaction is quite energy-intensive (2 - 5 kWh per liter LHe, without auxiliary units; thermodynamically inevitable due to Carnot factor, moreover due to realizable plant efficiencies). Helium liquefied at ultra-low temperatures in a central facility must be transfilled into mobile insulated dewar vessels for transportation to the respective points of use. This transfill procedure is a major loss factor: standard today is the use of single-flow vacuum-insulated transfer lines. The mass flow is caused by pressurization in the starting tank. This results in large evaporation losses. When transfilling a certain quantity of LHe, further 30% of this quantity undergoes evaporation and must be recovered as flash gas during the filling process, later be processed again completely. In Germany alone, there are around 100 such helium plants in use, most of which are centrally operated (each comprising helium recovery, re-liquefaction and LHe transfill stations). Typical delivery quantities are 80,000 - 200,000 liters of LHe per year, which are required as a refrigerant by the institution in question. So we are talking about considerable quantities. The flash gas reprocessing - comprising recovery, intermediate storage, compression to high pressure, high pressure storage, cleaning and re-liquefaction - is very energy-intensive, in addition to runtime-dependent service and personnel costs. A considerable proportion of the respective equipment capacity is inevitably occupied by this flash gas processing. Many of these helium plants are already running at the limits of their capacity (due to the generally increasing demand for LHe everywhere) and would normally have to be replaced with larger new plants for this reason. The applicant, responsible for the central helium plant at TU Dresden and the LHe supply there, has already been able to implement an extremely improved transfill system at his own plant. A dual flow vacuum-insulated transfer line is used. The mass flow is no longer achieved by pressurization or differential pressure between primary storage and mobile dewar, but by a 4 K cryogenic turbopump developed in-house. By that, almost all of the inevitable loss factors in the above-mentioned single-flow filling process can be overcome or greatly reduced (ultimately to a few % of the filled quantity). The aim of the project is to further develop this technology in such a way that such dual-flow pump driven transfer devices can be used as a kind of “conversion kit” for the majority of the helium systems mentioned. Thus effecting a significant better overal efficiency.

• DFG Programme: Further Instrumentation Related Funding
• Major Instrumentation: zweiflutiger LHe-Transferheber (2 Ausf.)
• Instrumentation Group: 8590 Sonstige Kälteanlagen und -geräte (außer 850-858)