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LiquefactionLH2 Production Processes Linde-Hampson Process The Linde-Hampson method is a thermodynamic process, where isothermal compreesion and subsequent isobaric cooling is done in a heat exchanger. Joule-Thompson expansion connected with an irreversible change in entropy is used as the refrigeration process. Despite its simplicity and reliability, this method has become less attractive compared to modern ones, where cooling is carried out in reversible processes (expander) at reduced energy consumption. Claude Process A commonly applied method in large-scale liquefaction plants is the Claude process, where the necessary refrigeration is provided in four main steps 1. Compression of hydrogen gas, removal of compression heat; 2. Precooling with liquid nitrogen (80 K); 3. Cooling of a part of the hydrogen in an expander (30 K) 4. Expanding of the residual hydrogen in a Joule-Thompson valve (20 K) Joule-Thompson expansion is applied for the final step to avoid two-phase flow in the expander. Further improvement in efficiency is expected with the development of new materials and new compression/expansion technology. Magnetic Refrigeration Process A qualitatively new approach is the magnetic refrigeration process takes advantage of the entropy difference and the adiabatic temperature change upon application or removal of magnetic fields in the working material. It uses isentropic demagnetization of a ferromagnetic material as cooling process. It is expected that 15 separate cooling stages are necessary for hydrogen o get down to the boiling point. This method is still on an R&D level, but it appears promising because of its compact cooling device with long lifetime, low capital investment, and higher efficiency with an estimated liquefaction work of 7.3 kWh/kg. << Compressors | Content | Storage - Introduction >> |