PARAMETRIZATION OF THE HEAT AND MASS EXCHANGE PROCESS IN THE SURFACE ATMOSPHERIC LAYER

When constructing numerical models of the atmosphere and the surface atmospheric layer (PAS) interacting with it, the “parametrization” approach is used, that is, the representation of processes with scales smaller than the scale of the cells of the computational grid intended for modeling processes of larger scales.

Modern approaches to the intensification of heat and mass exchange in multi-temperature condensation filters

The article considers the problems and features of heat and mass exchange on developed surfaces in the conditions of both single-phase and vapour-liquid flow during its condensation. We give a brief analytical review of studies of hydrodynamics and heat exchange in such systems. We analyzed the efficiency of the working channel of the condensation filter and identified problematic points. We offer possible methods for intensifying heat and mass transfer on working surfaces.

Features of the thermal regime formation in the downcast shafts in the cold period of the year

In the cold period of the year, to ensure the required thermal regime in underground mine workings, the air supplied to the mine is heated using air handling systems. In future, the thermodynamic state of the prepared air flow when it is lowered along the mine shaft changes due to the influence of a number of factors. At the same time, the processes of heat and mass exchange between the incoming air and its environment are of particular interest. These processes directly depend on the initial parameters of the heated air, the downcast shaft depth and the presence of water flows into the mine shaft. Based on the obtained experimental data and theoretical studies, the analysis of the influence of various heat and mass transfer factors on the formation of microclimatic parameters of air in the downcast shafts of the Norilsk industrial district mines is carried out. It is shown that in the presence of external water flows from the flooded rocks behind the shaft lining, the microclimatic parameters of the air in the shaft are determined by the heat transfer from the incoming air flow to the underground water flowing down the downcast shaft lining. The research results made it possible to describe and explain the effect of lowering the air temperature entering the underground workings of deep mines

Giant ice rings in southern Baikal: multi-satellite data help to study ice cover dynamics and eddies under ice

Ice cover on lakes is subject to atmospheric forcing from above and the influence of water dynamics and heat flux from below. One characteristic example of these influences in some large lakes, such as Lake Baikal in Russia, are the giant ice rings and the associated eddies under the ice cover. In April 2020 a giant ice ring appeared in southern Baikal, and a lens-like eddy was detected below the ice. We analysed the temporal changes of ice cover using satellite images from multiple satellite missions – MODIS on Terra and Aqua, Sentinel-1 SAR, Sentinel 2 MSI, Landsat 8, PlanetScope, satellite photography from the International Space Station, and radar altimetry data from Jason-3. Satellite imagery and meteorological data show unusual temporal changes of ice colour in April 2020, which were explained by water infiltration into the ice followed by the competing influences of cold air from above and the warm eddy below the ice. Tracking of ice floe displacement also makes it possible to estimate eddy currents and their influence on the upper water layer. Multi-satellite data contribute to a better understanding of the development of ice cover in the presence of eddies, the role of eddies in horizontal and vertical heat and mass exchange, and their impact on the chemistry and biology of the lakes and on human activity.

Experimental Study of Thermal Performance of Different Fruit Packaging Box Designs

Packaging was recently identified as an essential element in addressing the key challenge of sustainable food supply and is gaining interest among researchers. It is a central element in food quality preservation due to its role in heat and mass exchange with the external atmosphere, contributing to the preservation of food quality during storage and extending food shelf life. This work proposes three new packaging configurations with the same size but different geometry and ventilation hole sizes and geometry, that change the conditions in which the heat and mass exchange occurs, during either the cooling period of fruits, inside the cooling chamber, or during the period when the packaging is exposed to ambient conditions, outside the cooling chamber. For this purpose, packages with fruit models that replicate the properties of real fruit were subjected to a cooling process inside a cooling chamber for 8 h. Subsequently, during the heating phase, the packages were exposed to ambient conditions for 10 h. Thermal conditions were also monitored, both inside and outside the chamber. Additionally, for comparative purposes, the thermal behavior of commercial packaging was also evaluated for the same operating conditions in the cooling and heating phases. The results show that the new packages do not substantially promote the preservation of fruits in the cooling phase, but in the heating phase, they ensure an extension of the period with proper thermal conditions of up to 50% in relation to the conventional packaging. This result is particularly important since the heating phase, in which fruits are outside the storage chamber, is the period with the greatest impact on the fruits’ useful life.

Novel Cast Polyurethanes Obtained by Using Reactive Phosphorus-Containing Polyol: Synthesis, Thermal Analysis and Combustion Behaviors

Phosphorus-containing polyol applications in polyurethane synthesis can prevent volatilization of flame retardants and their migration on the surface of a material. In this work, novel cast polyurethanes were prepared by a one-step method with the use of different amounts of phosphorus-containing polyol, 4,4′–diphenylmethane diisocyanate and 1,4-butanediol. The chemical structure, thermal, physicochemical and mechanical properties and flame resistance of the prepared materials were investigated. The results obtained for cast flame-retarded polyurethanes were compared with cast polyurethane synthesized with commonly known polyether polyol. It has been shown that with an increasing amount of phosphorus content to polyurethane’s chemical structure, an increased flame resistance and char yield were found during combustion tests. Phosphorus polyol worked in both the condensed (reduced heat and mass exchange) and gas phase (inhibition of flame propagation during burning). The obtained materials contained phosphorus polyol, indicating higher thermal stability in an oxidative environment than an inert atmosphere.

Giant ice rings in Southern Baikal: multi-satellite data help to study ice cover evolution and eddies under ice

Ice cover on lakes is subject to atmospheric forcing from above and the influence of water dynamics and heat flux from below. One characteristic example of these influences in some large lakes, such as Lake Baikal in Russia, are the giant ice rings and the associated eddies under the ice cover. In April 2020 a giant ice ring appeared in Southern Baikal and a lens-like eddy was detected below the ice. We analysed the temporal evolution of ice cover using satellite images from multiple satellite missions – MODIS on Terra and Aqua, Sentinel-1 SAR, Sentinel 2 MSI, Landsat-8, PlanetScope, satellite photography from International Space Station, and radar altimetry data from Jason-3. Satellite imagery and meteorological data show an unusual temporal evolution of ice colour in April 2020, which was explained by water infiltration into the ice followed by the competing influences of cold air from above and the warm eddy below the ice. Tracking of ice floe displacement also makes it possible to estimate eddy currents and their influence on the upper water layer. Multi-satellite data contribute to a better understanding of the evolution of ice cover in the presence of eddies, role of eddies in horizontal and vertical heat and mass exchange and their impact on the chemistry and biology of the lakes and on human activity.

Improving energy efficiency of the systems for obtaining water from atmospheric air

This paper outlines the prospect of obtaining water from atmospheric air by cooling it to the dew point temperature using refrigeration machines in order to partially reduce water scarcity in the arid regions of our planet. To minimize energy costs in the systems for obtaining water from atmospheric air, it is proposed to utilize solar energy with absorption refrigeration units (ARUs) acting as a source of artificial cold. The characteristic thermodynamic processes have been analyzed in a modernized ARU, capable of working at a lower thermal energy source's temperature than its analogs. The possibility has been studied to reduce the temperature of the heat source by including a solution vaporizer in the ARU scheme. The analysis involved an authentic method based on the balance of specific streams of ARU working body components and actual boundary conditions at characteristic points of the cycle. A limit was shown for the level of a minimum boiling temperature in the ARU generator (from 90 °C) when the systems for obtaining water from atmospheric air are operated under current climatic conditions. The simulation of heat-and-mass exchange processes during contact interaction between a steam-gas mixture and ammonia water solution was carried out. Based on variant calculations, it has been shown that the proposed ARU structure with an adiabatic solution vaporizer could work as part of systems to obtain water from atmospheric air at a hot spring temperature above 100 °C and constructively enough fits into the element base of standard models. It has been proposed to use two types of solar thermal energy sources to operate ARU. In a tropical climate, with vacuum solar collectors or solar energy hubs; in a temperate climate zone, with solar collectors with water as a heat carrier

Well-Posedness and Stability Result of the Nonlinear Thermodiffusion Full von Kármán Beam with Thermal Effect and Time-Varying Delay

In this work, we consider a new full von Kármán beam model with thermal and mass diffusion effects according to the Gurtin-Pinkin model combined with time-varying delay. Heat and mass exchange with the environment during thermodiffusion in the von Kármán beam. We establish the well-posedness and the exponential stability of the system by the energy method under suitable conditions.