Modelling the Optimal Schemes of Population Vaccination Using Epidemiological Data

І E Furtat

doi:10.32626/2308-5916.2019-20.104-113

Abstract

Condensation upon direct contact of the phases can be divided into the following types: condensation of the steam stream in the volume of unheated liquid; condensation of vapor bubbles in liquid; condensation of steam by liquid droplets (dispersed liquid); vapor condensation on a jet of liquid.In visual experiments, the study of the process of condensation of the jet of steam in space was noted by the presence of a white emulsion at the collision of steam with liquid, due to the crushing of a jet of steam into small bubbles. The high intensity of the heat transfer process was explained by the sharp increase in the contact surface. When considering the structure of the flow taking into account the two-phase region, it can be noted that there is a smooth conical surface of the separation between the phases and the formation of dispersed bubbles and droplets in the flow. This allows to determine the dependence of the geometry of the contact zone of the phases on the temperature head.An increase in the surface area of the contact phase can be achieved by dispersing one of the contacting phases. Existing liquid spraying machines have significant energy costs as a result of doing some work to overcome the surface tension that causes the liquid to reduce the free surface.So the heat transfer between a liquid drop and a saturated vapor is determined by the heat distribution along the drop radius. The vapor condenses on the surface of the liquid droplet, and the released heat condensation must be discharged inside the droplet. According to the equation of thermal conductivity under the relevant conditions of the problem under consideration, the intensity of condensation is determined by the rate of heat runoff per drop. Studies of heat exchange on dispersed jets of liquid have proven high intensity of the process.Condensation on a jet of liquid is used in many industrial devices (deaerators, condensers of mixing type, jet heaters).Theoretical and experimental studies of this type of condensation are scarce. Studies of heat exchange during condensation of a dispersed steam stream on a swirling stream of water are absent at all. The results of the experiments of heat exchange at the contact condensation of steam on jets of water, consisting of a continuous section and a section that falls into drops, are represented by the criterion equation. Recent studies are related to the development of a mathematical model for the calculation of jet condensation and analysis of past developments with its application.

Highlights

By analyzing the condensation in direct contact of the phases, it can be divided into the following types: condensation of steam stream in the volume of underheated liquid; condensation of vapor bubbles in the liquid; condensation of steam on liquid droplets; condensation of steam on a liquid jet.Note that during the condensation the non-condensing gas contained in vapor leads to a decrease in the heat transfer coefficient due to the additional diffusional thermal resistance.The first studies of the condensation process of a steam jet in a liquid filled space are based on visual experiments [1; 2]
The presence of a white emulsion was noted when the vapor collides with the liquid, due to the crushing of a steam jet into small bubbles
As stated in [3], the penetration of steam into water due to the difference of partial pressures of steam in the vapor medium and in the liquid causes the leakage of steam at high speed, which explains the presence of the emulsion

Summary

Introduction

By analyzing the condensation in direct contact of the phases, it can be divided into the following types: condensation of steam stream in the volume of underheated liquid; condensation of vapor bubbles in the liquid; condensation of steam on liquid droplets (dispersed liquid); condensation of steam on a liquid jet. Studies [4; 5] determined the theoretically obtained and experimentally confirmed position of the condensation surface depending on the parameters of the vapor and the liquid. It is known that there are no experiments, calculations for the detection of theoretical laws of heat and mass transfer when mixing a dispersed jet of steam with a jet of liquid This process is complex enough, so there is a need for experimental studies. On the basis of theoretical developments [22], the process of condensation at the outflow of a cold jet of liquid with velocity w0 from an aperture of radius R into the vapor space was studied in [27] with the assumption that «the molecular heat flow is less intense than turbulent». With regard to the above dependencies, we can conclude about their individuality due, firstly, to the method of obtaining, and secondly, to the differences in the method of determining the input parameters

Conclusions

КОНДЕНСАЦІЙНИЙ ТЕПЛОМАСООБМІН ПРИ ПРЯМОМУ КОНТАКТІ РЕАГУЮЧИХ ФАЗ