теплообмін

Моделювання процесу охолодження при критичних умовах за рахунок випаровування рідини

Побудовано модель процесу теплообміну в плоскій пластині, з поверхні якої на початковій стадії відведення тепла відбувається лише за рахунок конвекції. В момент, коли температура пластини стає критичною, на поверхню пластини подається рідина, за рахунок випаровування якої відбувається охолодження. Отримано числовий розв’язок модельної задачі. Проаналізовано динаміку тепловідведення та зміну температурного поля пластини.

Heat transfer analysis on magneto–ternary nanofluid flow in a porous medium over a moving surface

Researchers have become attracted with ternary hybrid nanoparticles because of its effectiveness in enhancing heat transfer and have gone on to further analyze the working fluid.  This study is focusing on magneto-ternary nanofluid flow in a porous medium over a moving plate with Joule heating.  The combination of TiO$_2$, SiO$_2$, and Al$_2$O$_3$ with water, H$_2$O, as the based fluid is used for the analysis.

Numerical solutions and stability analysis of unsteady hybrid nanofluid flow over a shrinking sheet with heat generation

The study focuses on the generation of multiple numerical solutions and stability analysis for the case of an unsteady copper-alumina/water hybrid nanofluid subjected to a shrinking sheet.  Heat generation as the potential contributing factor in the heat transfer progress is considered as well as the suction effect.  The governing model (partial differential equations) is developed based on the boundary layer assumptions, which then are transformed into a set of ordinary (similarity) differential equations.  The bvp4c solver is used to search all possible solutions and

Determination and analysis of the thermoelastic state of layered orthotropic cylindrical shells

The fundamental relations of the quasi-static problem of thermoelasticity are written for a finite layered orthotropic cylindrical shell of an antisymmetric structure.  Under convective heat transfer on the surfaces of this shell and under a linear dependence of temperature on the transverse coordinate, the basic system of equations for the integral characteristics of temperature is given.  The method is proposed for solving the formulated problems of thermoelasticity and thermal conductivity, using the double finite integral Fourier transform with respect to the corres

EFFECTIVE WALL STRUCTURES WITH USE OF FLAX STRAW CONCRETE

The modern building technologies are technologies of green construction, near zero-energy and active buildings with bioclimatic design, optimized energy consumption and CO2 emissions. Prospective enclosing structures of such buildings are structures using available, low cost, and environmentally friendly materials based on plant raw materials.

Quasi-static problem of thermoelasticity for layered shallow cylindrical shells of irregular structure

For rectangular layered shallow cylindrical shells of irregular structure, the quasi-static problem of unbound thermoelasticity is formulated.  As a mathematical model, the equations of the shear theory of shallow shells of Timoshenko type are used.  The closed solution for the formulated problem is found by the methods of integral transformations.  The distribution of temperature, displacements, forces and moments in a two-layer cylindrical shell under local convective heating is analyzed numerically.

MHD Nanofluid boundary layer flow over a stretching sheet with viscous, ohmic dissipation

The objective of this research is to examine the steady incompressible two-dimensional hydromagnetic boundary layer flow of nanofluid passing through a stretched sheet in the influence of viscous and ohmic dissipations.  The present problem is obtained with the help of an analytical technique called DTM-Pade Approximation.  The mathematical modeling of the flow is considered in the form of the partial differential equation and is transformed into a differential equation through suitable similarity transformation.  The force of fixed parameters like thermophoresis number

An improved Levenberg–Marquardt method for nonsmooth equations with application to multi-stream heat exchangers

Systems of nonsmooth equations are very useful in the study of nonlinear complementarity problems, variational inequality problems, bilevel programming problems, and arise in the mathematical modeling of many problems in chemical processing, mechanics and engineering.  In this paper, we introduce a hybrid method for solving systems of nonsmooth equations, which combines the idea of Levenberg–Marquardt–type methods with bundle techniques, while avoiding the hypothesis of differentiability of the least squares merit function.  Some numerical results comparing the proposed method with LP-Newto

THE ANALYSIS OF WATER SPEED INFLUENCE IN HOT-WATER DISTRIBUTION SYSTEM ON THE AMOUNT OF HEAT LOSS

One of the main tasks around the world is to reduce energy consumption with constant consumer comfort. The hot water supply system uses a significant part of thermal energy and requires no less attention than the heating or ventilation system. The amount of heat loss from hot water distribution systems is of great importance for the energy consumption of buildings. In winter, part of this heat is used for space heating, in summer they are unused and is considered as lost heat. 

МАТЕМАТИЧНІ МОДЕЛІ ТЕПЛООБМІНУ В ЕЛЕМЕНТАХ ТУРБОГЕНЕРАТОРІВ (ПРОДОВЖЕННЯ)

Удосконалено раніше розроблені [8] та наведено нові математичні моделі аналізу температурних режимів у окремих елементах турбогенераторів, які геометрично описано ізотропними півпростором і простором із внутрішнім джерелом тепла циліндричної форми. Також розглянуто випадки для півпростору, коли тепловиділяючий циліндр є тонким, а для простору, коли він є термочутливим. Для цього з використанням теорії узагальнених функцій у зручній формі записано остаточні диференціальні рівняння теплопровідності з крайовими умовами.