Superfluid He II cooling for high field superconducting magnets has been developed using the opportunity of large scale project in fusion power generation and high energy physics laboratories. The magnets are cryostated at temperature as low as 1.8 K. The necessary energy input for 1 W of cooling power at 1.8 K is of the order of 1 kW and the use of superfluid helium at the temperature below 2.0 K requires efficient and low energy consuming cryostats. The cryostat design can be optimized on the basis of the Second Law of Thermodynamics with use of entropy generation minimization method, within the boundary and technical constraints of the device. The paper presents the discussion of theoretical background of entropy generation minimization method and gives the example from the cryostat design practice. The basic scheme of superfluid pressurized He II cryostat is given.The He II cryostat built in the Institute of Power Engineering and Fluid Mechanics is described together with the optimization procedure of the cryostat thermal insulation system based on the entropy minimization method.
Omówiono doświadczenia ze współpracy Konsorcjum Polskich Uczelni z Grupą EDF Polska w zakresie nowych technologii w energetyce. Przedstawiony model współpracy dużego koncernu z uczelniami pozwala na uniknięcie powtórzeń badań i powielania wyników.
EN
Discussed is experience gained during cooperation of Consortium of Polish Universities with EDF Group Polska in the field of new technologies in power industry. Presented cooperation model of a big company with a group of universities enables avoiding research repeating and result duplicating.
W artykule zwrócono uwagę na własności wybranych materiałów konstrukcyjnych w niskich temperaturach, w tym przede wszystkim na ich plastyczność (ciągliwość ) oraz na zjawisko tzw. kruchości wodorowej. Zagadnienia te są niezwykle ważne w projektowaniu i budowie urządzeń kriogenicznych, bowiem ich występowanie może stanowić zagrożenie dla bezpieczeństwa ludzi i sprzętu w warunkach wychłodzenia.
EN
The properties ot selected structural materials at low temperatures, especially plasticity and ductility as well as hydrogen embrittlement have be en discussed in the paper. These problems are very important for design and construction of cryogenics systems because ot safety reasons tor people and equipment.
W artykule zwrócono uwagę na miejsce gazu ziemnego jako najważniejszego obecnie paliwa gazowego i jednocześnie surowca energetycznego o wciąż rosnącym znaczeniu. Podano przykładowe składy takiego gazu pozyskiwanego w wybranych rejonach świata. Omówiono wybrane metody skraplania gazu ziemnego, a są to jednostopniowa chłodziarka Joule-Thomsona lub Braytona, układ kaskadowy z użyciem trzech czynników z zaworami dławiącymi lub z rozprężarkami, a także układ z jedną sprężarka i pewną liczbą separatorów cieczy, dzięki czemu unika się zamarzania wyżej wrzących czynników w niskich temperaturach.
EN
A role ot natural gas as the most important contemporary gas fuel as well as an energy source of growing importance have been discussed. The exemplary constitutions ot natural gas mined in various regions in the world have been given. The following selected methods ot natural gas condensation have been presented: one-stage device of Joule-Thomson and Brayton cycles, three-stage cascade systems equipped with throtlling valves or expanders, as well as multistage systems equipped with one compressor and few liquid-vapour separators, thanks to which freezing of high-boiling fluids can be avoided under conditions of low temperature.
Hydrogen energy cycle in a decentralized economy is a subject of discussion and research effort to find justification for usage of liquid hydrogen in conjunction with SOFC and SOEC and superconducting energy storage devices. The renewable energy sources are envisage to provide electricity to split water to H2and O2 using high temperature electrolysis which can be beneficial thanks to the decrease of the energy demand due to the thermodynamics and improved electrochemical kinetics. Additionally O2 and H2 can be effective cryogenic liquids with boiling temperatures of 55K (under lower pressure) and 20K respectively. It is proposed that both gases O2 and H2 can be used in conjunction with recently developed mix gas cryocooler working at very low pressure and providing refrigeration at temperature below inversion temperature of hydrogen (118K). Liquefied hydrogen at temperature of 20K is a very efficient coolant for high temperature superconducting energy storage devices such flywheel and even SMES made from MgB2. The H2 and O2 can be used in SOFC or PFC generating electricity when it is needed. The fact that SOFC is exothermic and SOEC is endothermic, enable realisation of the thermally balanced heat and electricity cycle. It was concluded that combination of the balanced SOFC/SOEC stacks in conjunction with liquefaction of the H2 and O2 products makes the overall LH2energy cycle sustainable and applicable to other modern energy storage devices such as superconducting flywheel.
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