Study of Pluto’s atmosphere based on 2020 stellar occultation light curve results

On 6 June 2020, Pluto’s stellar occultation was successfully observed at a ground-based observatory in Iran, and Pluto’s atmospheric parameters were investigated. We used an atmospheric model of Pluto, assuming a spherical and transparent pure N2 atmosphere. Using ray-tracing code, the stellar occultation light curve was satisfactorily fit to this model. We found that Pluto’s atmospheric pressure at the reference radius of 1215 km was 6.72 ± 0.48 μbar in June 2020. Our estimated pressure shows a continuation of the pressure increase trend observed since 1988 and does not confirm the rapid pressure decrease tentatively reported in 2019. The pressure evolution is consistent with a seasonal transport model. We conclude that the N2 sublimation process from Sputnik Planitia is continuing. This study’s result is shown on the diagram of the annual evolution of atmospheric pressure.

Influence of sublimation process on air permeability and water absorption dynamics

PurposeThe purpose of this research was to find the influence of sublimation process on air permeability and water absorption dynamics of knitted and woven polyester-based fabrics.Design/methodology/approachThree different sublimation designs were prepared and applied (keeping the same sublimation parameters) for eight variants of knitted and four variants of woven polyester-based fabrics. Air permeability and water absorption dynamics during 180s period was measured and compared before and after the sublimation process.FindingsAccording to the obtained results, high temperature and pressure applied in sublimation process have influence on the porosity and air permeability of knitted fabrics; however, the influence on water absorption dynamics is minimal. Sublimation design dos not have any influence on the mentioned properties.Originality/valueThe obtained results of the sublimation process influence on air permeability and water absorption dynamics of knitted and woven polyester-based fabrics will help to understand how sublimation process can affect comfort properties of textile fabrics.

Recirculating carbon dioxide refrigeration unit for freezing food

The article describes the development process of a refrigeration unit using carbon dioxide as a refrigerant. A feature of the plant is the possibility of recirculating carbon dioxide. The authors substantiate the use of the natural substance CO2 as a refrigerant and consider the prospects for using the refrigerant R744. The efficiency of the cycle of a one-stage subcritical refrigeration unit is analyzed. The authors have designed a recirculating carbon dioxide refrigeration unit based on the traditional subcritical cycle. The essential and auxiliary components of the refrigeration machine were presented and described. The developed scheme allows freezing food products by direct contact of the product with snow-like carbon dioxide. After that, the sublimation process takes place in the freezing chamber and the gas-liquid mixture is sent through the liquid separator for recirculation. The article describes the operation of the system diagram, the principle of operation, and the purpose of the elements of automation and regulation.