Equivalent isentropic expansion efficiency of real fluid subject to concurrent pressure drop and heat transfer

[摘要] Concurrent pressure drop and cooling of a super-critical or sub-cooled liquid stream can have the same effect as adiabatic expansion even though there is no work extraction. A practical implementation is as straight forward as counter-flow heat exchange with a colder fluid. The concurrent pressure drop need not be continuous with respect to the heat exchange, but may occur in a step-wise manner, in between heat exchange. Two aspects of this effect of pressure drop with heat transfer are examined; a thermodynamic and a practical process equivalent isentropic expansion efficiency. This real fluid phenomenon is useful to understand in applications where work extraction is either not practical or has not been developed. A super-critical helium supply, often around 3 bar and 4.5 K, being ultimately used as a superfluid (usually around 1.8 to 2.1 K) to cool a Niobium superconducting radio frequency cavity or a superconducting magnet is one such particular application. This paper examines the thermodynamic nature of this phenomenon.

[发布机构] Facility for Rare Isotope Beams (FRIB), Michigan State University (MSU), East Lansing; MI; 48824, United States^1

[效力级别] 物理学 [学科分类] 材料科学（综合）

[关键词] Adiabatic expansion;Counter-flows;Effect of pressure;Isentropic expansion;Liquid streams;Practical process;Superconducting radio frequency;Work extraction