scholarly journals Thermal modes simulation of cooling panels in waste water pumping stations

Vestnik MGSU ◽  
2021 ◽  
pp. 1378-1387
Author(s):  
Vitaly I. Prohorov ◽  
Muhammet A. Razakov
Keyword(s):  
Waste Water ◽  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Conditions ◽  
Engineering Calculation ◽  
Transfer Coefficients ◽  
Pumping Station ◽  
Heat Transfer Coefficients ◽  
Water Pumping ◽  
Functional Areas

Introduction. Authors considers a new method of cooling some functional areas in a city sewage pumping station. They have used the works of Isachenko V.A., Osipov V.A., Sukomel A.S., Bogoslovsky V.N. to simulate the PLI panel’s stationary thermal regime. Materials and methods. Authors have considered the mathematical modeling of stationary and non-stationary thermal phenomena in the PLI panel in this paper. There are the possibilities of modeling the thermal modes of the panel PLI which depending on the place of installation of this device. Authors have given the theoretical characteristics of the heated air in this device and some results of survey in a high voltage urban waste water pumping station in Moscow. There are the heat inputs and heat losses calculations of PLI panel’s various structural elements which carried out using the theory of similarity in this article. Researchers considered the possibility of use other empirical results to determine some of the coefficients which involved in modeling. It has been presented different heat transfer coefficients which could be used in thermal conditions model of PLI panel. There are the validation of the developed models which proved by comparing the deviations in the heat balance equation of the PLI panel. Results. Authors has developed a physical and mathematical model of PLI panel’s thermal modes for a sewage pimping station. Authors have given the recommendations on the possibility of using the different heat transfer coefficients in PLI panel’s thermal conditions modeling process. A numerical experiment was carried out to simulate one PLI panel under the conditions of a sewage pumping station by researchers in this paper. Conclusions. According to the information, this physical and mathematical model can be used for engineering calculation when engineer is selecting the characteristics of PLI panel and also it could be used to clarifying the distributions of heat flow from PLI panel.

scholarly journals Modeling of the Two-Dimensional Thawing of Logs in an Air Environment

2020 ◽  
Author(s):  
Nencho Deliiski ◽  
Ladislav Dzurenda ◽  
Natalia Tumbarkova
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Experimental Studies ◽  
Longitudinal Section ◽  
Nonstationary Temperature ◽  
Two Dimensional ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
The Finite Difference Method

A two-dimensional mathematical model has been created, solved, and verified for the transient nonlinear heat conduction in logs during their thawing in an air environment. For the numerical solution of the model, an explicit form of the finite-difference method in the computing medium of Visual FORTRAN Professional has been used. The chapter presents solutions of the model and its validation towards own experimental studies. During the validation of the model, the inverse task of the heat transfer has been solved for the determination of the logs’ heat transfer coefficients in radial and longitudinal directions. This task has been solved also in regard to the logs’ surface temperature, which depends on the mentioned coefficients. The results from the experimental and simulative investigation of 2D nonstationary temperature distribution in the longitudinal section of poplar logs with a diameter of 0.24 m, length of 0.48 m, and an initial temperature of approximately –30°C during their many hours thawing in an air environment at room temperature are presented, visualized, and analyzed.

Modeling of work of plate water evaporation coolers of indirect operation principle

10.12737/2199 ◽  
2014 ◽  
Vol 3 (4) ◽  
pp. 160-166
Author(s):  
Шацкий ◽  
Vladimir Shatskiy ◽  
Гулевский ◽  
Vyacheslav Gulevskiy
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Boundary Conditions ◽  
Cross Section ◽  
Parabolic Type ◽  
Water Evaporation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Proposed Model ◽  
Complex Mathematical Model

More complex mathematical model is proposed which is a system of partial differential equations of elliptic and parabolic type with the corresponding initial and boundary conditions, which are not involved in the heat transfer coefficients, the deter-mination of the numerical values of which is very difficult. For its implementation diffe-rence analogue of the proposed model was built with Nx steps along the length of the channel, Ny steps along the section of channels, Ny / 2 +1 steps of the cross section of the plate. The presented model and the method of its implementation makes it possible to determine the temperature of the air flows along the length of coolers that offers a choice of the geometric parameters.

scholarly journals APPROACH TO DETERMINING BOUNDARY CONDITIONS ON THE EXTERNAL SURFACE OF THE HEIGHT CASE OF THE ADMINISTRATIVE BUILDING

2021 ◽  
pp. 73-79
Author(s):  
N.О. ORLOVA
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Wind Speed ◽  
Air Temperature ◽  
Thermal Regime ◽  
Energy System ◽  
Building Envelope ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
The Mathematical Model

Problem statement. The influence of the external climate on the thermal regime of the enclosures of premises and buildings is complex. The calculated values and combinations of parameters are determined, as a rule, taking into account the security factor of the calculated conditions. The main indicators of the cold season are the outdoor temperature and wind speed. As you know, an increase in wind speed with a constant outside air temperature causes an increase in pressure on the windward facade of the building, as a result of which the heat loss of the room, associated with heating of the incoming air, increases. Wind speed and direction have a stronger influence on the distribution of air flows in the ventilation system and on the infiltration costs than the outside temperature. A change in the outside air temperature from −15 to −30 °С leads to the same increase in air exchange in the apartment as an increase in wind speed from 3 to 6 m/s. The purpose of the article is to determine the heat transfer coefficients on the outside of an office building. Results. The basic principles of calculating heat transfer coefficients are presented. The zoning of the premises of the Institute is proposed, taking into account their thermal regime and boundary conditions on external surfaces. Scientific novelty and practical significance. The original values of the heat transfer coefficients, which are considered on the example of the climatic conditions of the city of Kharkov for the IP Mash complex of the NAS of Ukraine. On the basis of the presented methodology for determining the heat transfer coefficients, it is planned to present this building as a single energy system with three main energetically interconnected subsystems: the energy effect of the external climate on the building envelope; energy that is contained in the building envelope, that is, in the external building envelope; energy, which is contained within the volume of the building, that is, in the internal air, internal equipment, internal structures, etc. Then the mathematical model of the building as a unified energy system will consist of three submodels: the mathematical model of the influence of the external climate on the building envelope; mathematical model of heat transfer through the building envelope; mathematical model of radiant and convective heat transfer in the premises of the building.

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