Joule cycle

Bowman, R.C., )r., Kiehl, B Mar-quardt, E. (2003) Closed-Cycle Joule-Thomson Cryocoolers, in Spacecraft Thermal Control Handbook, Volume II Cryogenics (ed. M. Donabedian),... 

These refrigerators are used in miniature glass or metal dewars. A small gas tank can maintain the required operating temperature in a dewar for several hours. As described here, this is an open-cycle process the gas eventually runs out since it leaves the refrigerator. If the gas is collected and compressed, it can be recirculated indefinitely. A device that operates in this way is called a closed-cycle Joule-Thompson refrigerator. See Hudson (1969, pp. 380-384 and 387-388) for a more detailed description of these refrigerators. 

To reduce the work of compression in this cycle a two-stage or dualpressure process may be usedwhereby the pressure is reduced by two successive isenthalpic expansions. Since the isothermal work of compression is approximately proportional to the logarithm of the pressure ratio, and the Joule-Tnomson cooling is roughly proportional to... 

The Joule-Brayton (JB) constant pressure closed cycle is the basis of the cyclic gas turbine power plant, with steady flow of air (or gas) through a compressor, heater, turbine, cooler within a closed circuit (Fig. 1.4). The turbine drives the compressor and a generator delivering the electrical power, heat is supplied at a constant pressure and is also rejected at constant pressure. The temperature-entropy diagram for this cycle is also... 

Temperature - entropy diagram Fig. 1.4. Joule-Brayton cycle (after Ref. [1]). 

For an irreversible gas turbine cycle (the irreversible Joule-Brayton (UB) cycle of Fig. 1.9), less than unity) and < 1 so that the thermal efficiency is... 

We next consider the application of the exergy flux equation to a closed cycle plant based on the Joule-Brayton (JB) cycle (see Fig. 1.4), but with irreversible compression and expansion processes—an irreversible Joule-Brayton (IJB) cycle. The T,.s diagram is as shown in Fig. 2.6. 

The reversible simple (Joule-Brayton) cycle, [CHTJn... 

We use the original Joule-Bray ton cycle as a standard—an internally reversible closed gas turbine cycle 1,2,3,4 (see the T, s diagram of Fig. 3.1), with a maximum temperature 3 = Tb and a pressure ratio r. The minimum temperature is taken as 7, the ambient temperature, so that 7, = 7. ... 

The material is organized according to the class of hetero cycle formed, independent of the kind of reaction employed. The classification is taken from the book of Joule and Mills [12]. 

An apparatus which demonstrates the Gough-Joule effect. It comprises a pendulum adjusted so that a rubber sample is under stretch. Heat from a lamp causes the rubber to contract and swing the pendulum. This pulls the rubber into a shaded section where it extends and moves the pendulum back to the original position, whereupon the cycle is repeated. 

For laboratory production of LHe, other so-called Collins-type liquefiers have been built with one or two stages of GM cooling before the Joule-Thomson expansion (e.g. ref. [50]). The thermodynamic analysis of Collins helium liquefaction cycle can be found in ref. [51]. 

The fluid mixtures which have been used down to 80 K include nitrogen with roughly equal parts of methane, ethane and propane. Input pressures are 10MPa and overall efficiencies are much greater than single-fluid Joule-Thomson systems and are comparable with the GM and Stirling cycles (see also [55]). 

Fig. 5.15. Schematic diagram of Joule-Thomson (a) and Brayton (b) cooling cycles [60].

This cycle also uses continuous counterflow heat exchanger and is closely related to the Joule-Thomson and Claude cycles as shown in Fig. 5.15(a) [60], The cryocooling or reverse Brayton cycle derives from a reciprocating gas engine patented by G. B. Brayton in... 

Joule-Thomson expansion cycle, 8 42-43 Joule-Thomson expansion coefficients, for hydrogen, 13 764 Journal bearing, 15 211 Journal of Biotechnology and Bioengineering, 11 10 Journal of Physical and Chemical Reference Data, 15 141, 769 Journal of Research of the National... 

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