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Contemporary Machining Processes for New Materials
Published in E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan, Remanufacturing and Advanced Machining Processes for New Materials and Components, 2022
E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan
Physical blowing agents in a liquid or gaseous state under pressure are injected into a molten polymer, mainly inside a plasticating cylinder. The counterpressure in the cylinder prevents the mixture from bubbling, so that gas is solved in the polymer molt reducing its viscosity. It should be noted, however, that the effect on viscosity is dependent on many factors. It was demonstrated that mass fractions of blowing agents propane and carbon dioxide below 2 wt% had little to no effect in regard to viscosity reduction of a polypropylene melt, but a mass fraction of 3.5 wt% resulted in significantly decreased viscosity values (Vincent et al., 2020). Injected into a mold cavity, a polymer melt is foaming due to the lack of counterpressure, forming pores in the polymer. Usually, supercritical carbon dioxide (scCO2), nitrogen, and air, but also various ecological gas mixtures are applied as processing solvents. The Montreal Protocol and its subsequent amendments to the Vienna Convention for the Protection of the Ozone Layer have led to the introduction of “second-generation” blowing agents, such as hydrofluorocarbons (HFCs) or hydrocarbons. Zero ozone-depleting hydrocarbon blowing agents comprise n-pentane, isopentane, or cyclopentane (Höfer, 2012). Application of some other blowing agents, such as methylene chloride, becomes more and more limited under the air toxics legislation within various states considering it a suspected carcinogen (Kaufman and Overcash, 1993; Jimoda, 2011).
Butane and Naphtha Hydroisomerization
Published in Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk, Petroleum Refining, 2019
Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk
There are three pentane isomers: n-pentane, isopentane (2-methylbutane), and neopentane (2,2-dimethylpropane). Neopentane is practically never formed during pentane hydroisomerization, because there is no catalytic pathway that enables its formation. The only equilibrium that is of practical significance is that between n-pentane to isopentane.
Feedstock Composition and Properties
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
The fraction known as pentanes plus is a mixture of pentane isomers and higher molecular weight constituents (C5+) that is a liquid at ambient temperature and pressure, and consists mostly of pentanes and higher molecular weight (higher carbon number) hydrocarbon derivatives. Pentanes plus includes, but is not limited to, normal pentane, isopentane, hexanes-plus (natural gasoline), and condensate.
Strategic integration of single flash geothermal steam cycle (SFGSC) and ejector assisted dual-evaporator organic flash refrigeration cycle (EADEOFRC) for power and multi-temperature cooling: 2nd law performance study
Published in International Journal of Green Energy, 2022
Subha Mondal, Chitta Sahana, Sudipta De
In the present study, an ejector assisted organic flash refrigeration cycle with two evaporators is proposed and integrated with a flash geothermal steam cycle to produce cooling effects and the power output simultaneously. Before the vapor separator, a two-phase expander also has been placed to generate some output power along with refrigeration effects. Isopentane and n-pentane are considered as working fluids of the refrigeration cycle. The effects of parametric variations on the proposed cycle performance are initially demonstrated with isopentane. However, maximum achievable second law efficiencies and associated operating parameters of the combined cycle with both considered working fluids are finally summarized in Table 6 for a comparison.